Recent Advances in Mechanical Engineering

The current investigation highlights the impact of Diesel–biodiesel blends on performance and exhaust emission profiles of a single-cylinder, common rail direct injection (CRDI) engine. Experiments were performed at constant engine speed (1500 rpm) and three engine loads (50, 75 and 100%) under high fuel injection pressure (900 bar) with volume proportions (10, 20 and 30%) of Karanja with Diesel. Utilizing CRDI engine experimental data, an artificial intelligence (AI)-affiliated artificial neural network (ANN) model has been created with the intention of forecasting brake thermal efficiency, oxides of nitrogen, unburned hydrocarbon and carbon monoxide emissions. From various tested ANN models, one hidden layer with three neurons along with logsig transfer function has been noticed to be optimum network for Diesel-Karanja paradigms under high fuel injection pressure. While developing the optimum model, standard Levenberg–Marquardt training algorithm has been employed. The optimum ANN model is capable to estimate the CRDI engine performance–emission profiles with an overall correlation coefficient value of 0.99742, wherein 0.99783, 0.99951 and 0.99969 for training, validation and testing datasets, respectively. Results made clear that the formulated AI-based ANN model is viable for predicting the existing CRDI engine performance and emission profiles of Diesel-Karanja blends operating under high fuel injection pressure.

The present work investigates the ability of oxygenated Butanol on performance and exhaust emission characteristics of a single-cylinder, four-stroke, water-cooled, common rail direct injection (CRDI) engine. Experiments were performed at constant engine speed (1500 rpm) and six different load conditions, varying from 5 to 30 Nm. Based on CRDI engine experimental data, an artificial intelligence (AI)-affiliated adaptive neuro-fuzzy inference system (ANFIS) model has been formulated for predicting the output parameters, namely brake thermal efficiency (BTE), brake specific energy consumption (BSEC), oxides of nitrogen (NOX), unburned hydrocarbon (UBHC) and carbon monoxide (CO) by considering the engine load and Butanol share in the blend as input parameters. With the increasing Butanol share in the Diesel–Butanol blend, the BTE and BSEC were significantly increased, and exhaust gas emissions, especially NOX and CO, were also reduced. The developed AI-based ANFIS model has the capacity of mapping the relationship between input–output parameters of the CRDI engine with good accuracies. In this study, the statistical performances obtained from ANFIS predicted model are (0.0000107–0.0000755) of mean square error, (0.000353–0.001533) of mean square relative error, (0.999722–0.999939) of correlation coefficient and (0.999444–0.999878) of absolute fraction of variance, which elevated the model capability to a higher stage under Diesel–Butanol strategies.

The necessity to fabricate micron-sized objects at present is increasing rapidly. Planar parallel manipulators, an area of robotics, is also employed to develop motion stages for various applications. The present study proposes a 4-PP planar positioning motion stage. The end-effector of the proposed positioning stage undergoes motion along both the axis in a plane and restricts any angular motion. The planar parallel positioning device (manipulator) possesses four active input prismatic joints which are actuated by implementing Shape Memory Alloy (SMA) based smart material springs. The SMA spring-based actuators are very lightweight and provide higher work per unit mass in comparison to other actuators. The proposed manipulator possesses two degrees of freedom. This study presents the workspace analysis of the proposed manipulator actuated by smart materials. The study depicts the experimental workspace efficiency of 42.87% for the proposed motion stage in comparison to the feasible workspace region. The planar parallel motion stage has the ability to displace in microns within the workspace domain. This study also shows the adequacy of SMA spring-based actuators in the development of micro-positioning devices.Note: P represents a prismatic joint.

In recent times, the progress and activities on renewable energy sources are growing exponentially. Amongst the various kinds of renewable resources, wind energy is one of the most preferable due to its abundant availability, lesser cost, zero emission compared to other sources. Amongst the various kind of vertical axis wind turbines (VAWT), H-Darrieus rotor is more popular in the built environment for their simple constructions and higher power coefficient which also suffers from poor self-starting features. Again, the Savonius rotor is having the good self-starting ability but possess lesser power coefficient. To address all such limitations, existing investigations of hybrid H-Savonius rotor have been reported here in terms of the design, various parameters and aerodynamic performances which are used to improve their self-starting and efficiency. From this study, it is seen that the coaxial arrangement of the H-Savonius rotor is capable to exhibit higher efficiency and better self-starting characteristics than the staging assembly or the individual Savonius or H-rotor. Again, a newly designed hybrid H-Savonius rotor exhibits the maximum power coefficient of 0.414 at TSR2.5. Modification of the Savoniusblade and thicker H-rotor airfoil blade helps to increase the efficiency of the hybrid rotor. This present paper offers an overall idea on the research growth to improve the design and performance of the hybrid H-Darrieus rotor.

Storage of energy is an important technology to bridge the time and space gap between the source/supply and sink/utilization of energy. Thermal energy storage has emerged as a means to capture heat from both low- and high-temperature sources. Storage of waste heat and solar thermal energy is easier and cheaper with the application of sensible heat storage materials. However, the knowledge of thermal and physical properties of sensible heat storage materials is important for economical and effective heat storage. Therefore, this paper presents the thermal and economic aspects of liquid and solid-state sensible heat storage materials. Thermal aspects are important for designing of the energy storage systems, while economic considerations are important in material selection and payback calculations. From the thermo-economic studies, it is found that water and rocks have great potential as liquid and solid sensible heat storage materials, respectively, primarily due to their low cost. Water also has impressive thermal properties which makes its storage density higher as compared to other liquids. Also, cast iron and steel present good potential as heat storage materials due to their high thermal capacity.

In this work, a microchannel heat sink (MCHS) of dimension 40 mm × 40 mm × 14 mm with a circular copper tube (ID 0.8 mm) is designed, mimicking microelectronic component. The MCHS is subjected to a constant temperature condition which is mitigated via convective flow of single-phase fluid and different nanofluids. The investigation focused upon the heat transfer characteristics of all the coolants and to elucidate the effect of non-spherical nanoparticles in nanofluid. Here, the fluid flow and heat transfer parameters of the MCHS are focused experimentally at a constant Reynolds number of 1170 (velocity 1.19 m/s). Four coolants were used to study the heat transfer characteristics of the MCHS which was subjected to constant surface temperature of 125 °C, namely de-ionized (DI) water (hereafter abbreviated as water), Water + 0.0005% (v/v) CuO, Water + 0.0005% (v/v) multi-wall carbon nanotube (MWCNT) and DI water + 0.0005% (v/v) wax-intercalated MWCNT (WICNT). The wax is the phase change material (PCM) in this context which was encapsulated within MWCNT via self-sustained diffusion. Carbon nanotubes had an aspect ratio of 200. During the experiment, the temperature of particular depth within the MCHS from the surface was monitored. The maximum allowable limit of that particular point, aka the part of the integrated circuit (IC), was fixed between 70 and 50 °C, while the lower one is considered safe, whereas the upper one is critical for IC. It was seen that over a long period of unsteady-state investigation, the effect of WICNT was more pronounced in reducing the time required to lower the temperature to the safe operating limit. The cooling time of MCHS is reduced by 11.54% and 20.77% using Water + 0.0005% (v/v) multi-wall carbon nanotube and wax-intercalated MWCNT, respectively, over water which explains that WICNT enhances the heat transfer which is beneficial to increase the total operation time or computation time at the same memory usage rate.

The use of natural fibres has found impetus in recent times in place of conventional composites. Coconut is widely grown in tropical and subtropical regions. In the present work, an attempt has been made to study the use of coconut fibre as reinforcements in epoxy-based composites. The tensile and flexural properties of the coconut fibre-reinforced composite are studied to investigate its external load-carrying capacity. The quantity of fibre content was varied from 1% by weight, 3% by weight and 5% by weight of coconut fibre. These were employed as reinforcements in epoxy resin for both alkali-treated and untreated specimens. Alkali treatment enhanced the mechanical properties of the composites by providing better adhesive properties between matrix and fibre. The results revealed that composite having 3% by weight of treated coconut fibre showed the best tensile and flexural strength out of all the samples. In the light of these findings, it can be concluded that coconut fibre-reinforced composites may be used in various domestic, construction and industrial purposes. However, there is a dearth of research on how to further enhance their mechanical properties which might help in several applications by also reducing the quantity of natural waste produced by coconut fibres.

In recent years, the utility of polymer gear increased tremendously due to their substitutability over the conventional metallic gear for light load applications. The gear is subjected to complex working conditions during the meshing; therefore, manufacturing technique may play a crucial role to produce the gear with high material characteristics and dimensional accuracy. The injection molding process is one of the most useful techniques for mass manufacturing of the plastic parts and gear as well because this process offers lower production cost and superior profile accuracy. However, the injection molding product may contain some common defects, namely weld line, shrinkage, residual stress, deflection, etc. This study emphasized to find out the best gate location and gate number for the spur gear made of KEPITAL®F20-03 material. A set of designs and locations of the gate have been studied using molding software with the aim to minimize molding defects. The result shows that the polymer gear with four-gate central injection system (CIS) possessed better weld line location, the maximum value of minimum weld line meeting angle of 13.292°, the minimum value of maximum von Mises residual stress of 118.352 MPa and maximum weight of 11.57 g. However, the polymer gear with two-gate CIS possessed minimum value of maximum volumetric shrinkage of 14.454% and deflection of 0.26 mm.

Hydrostatic transmission (HST) system is widely used in the Heavy Earth Moving Machineries (HEMM). The hydro-motor used in the HST system provides the rotary motion for their traction, swing or other functions used in HEMM catering to different load profiles. This causes continuous variation in speed of the hydro-motor which reduces the efficiency of the HST system. Hence, controlling the speed of the hydro-motor is very much indeed. Constant speed of the hydro-motor can be achieved by controlling the input flow of it. Input flow can be controlled by controlling the displacement of the variable displacement hydraulic pump or by varying the flow through a proportional directional control valve (PDCV). The main objective of this research work is to design the PID controller which regulates the input flow to the hydro-motor so that the speed of the hydro-motor remains constant irrespective of the varying external load. To increase the PID controller performance, fuzzy control algorithm has been employed using MATLAB/Simulink environment. The main function of the fuzzy controller is to online tune the PID parameters which increase the performance of the drive. Comparison has been drawn based on the results obtained using Fuzzy-PID controller to the simple PID controller. The results show that Fuzzy tuned PID controller provides minimum settling time and less overshoot when compared to simple PID controller.

The research presented here studies heat transfer process in phase change material (PCM) in an enclosure under three different combinations of boundary heated surface. Isothermal conditions were imposed at the boundary, with adjacent sides and opposite sides heated. Numerical techniques were implemented to solve the governing equation employing “effective heat capacity” method for modelling of the phase change. The fastest melting was observed for adjacent heating walls, approximately 28.08 and 13.79% faster than other two. It was observed that natural convection is the main reason driving the pace of melting and has different impacts under different conditions. Natural convection is not significant while providing heat through vertical walls which also corresponds to slowest response time. The natural convection is also responsible for the wave-like shape attained by the solid–liquid interface. The pattern of melting signifies a symmetric melting pattern for the vertically heated sides.

Electromagnetic crimping is a high-speed joining by forming method that deforms electrically conducting materials using an electromagnetic field. This paper explores the finite element modelling of electromagnetic crimping of Cu-SS tube-to-tube joint with the use of LS-DYNA™ software which utilizes finite element method combined with the boundary element method. Simulations are performed at five different discharge energy values and stand-off distance, as well as the overlapped length of the tube is kept constant. Effect of discharge energies on the magnetic field, radial displacement and impact velocity and effect of plastic strain have been studied. The maximum magnetic field of 17 T is obtained at 6.2 kJ of discharge energy. The developed model can be used as a primary study to investigate interference-fit tube-to-tube joining by electromagnetic forming.

Numerical simulations using ANSYS Fluent 17.2 are carried out to explore the heat transfer characteristics of jet impingement on a protruded leading edge of a gas turbine blade. Many researchers have found that inclusion of protrusion does not improve Nusselt number though this contributes to augmentation in heat transfer due to an increase of surface area. In certain cases, the protrusion has also been found to degrade the heat transfer performance. Therefore, this work focuses on the effect of single protrusion to determine the effect of position of the protrusion on a concave surface and finally obtaining an optimized position of protrusions. The position of the single protrusion is varied at several angles with respect to the centre of the plate to explore the corresponding heat transfer characteristics. Thereafter, multiple protrusions are considered at desired positions to determine optimum effective location of protrusions for maximum heat transfer. The optimal position is determined using Genetic Algorithm.

Ultrasonic machining is one of the advanced machining processes, utilized for machining hard and brittle materials viz. ceramics, glass, titanium–aluminium composites, etc. for drilling operation with high precision. Horn is one of the important components in the ultrasonic machining process, which transfers longitudinal vibration from the transducer to the tool end. The present investigation considers the design of a simple three-dimensional cylindrical horn using different materials (aluminium, titanium, steel, stainless steel and mild steel) in dynamic conditions. COMSOL multiphysics, a finite element software, is used to investigate the effect of the materials on the horn performance. The results are presented in terms of amplitude, mode shape, and von Mises stress. The analysis results showed that aluminium is one of the suitable materials for horn design followed by titanium, steel, stainless steel, and mild steel. The aluminium horn showed a high amplitude of vibration at the horn end (20.12 μm) at the frequency of 18,445 due to the low damping coefficient. Other materials titanium (12.266 μm), steel (7.134 μm), mild steel (7.036 μm) and stainless steel (6.145 μm) have also shown reasonable amplitude at appropriate applied natural frequency.

Over exploitation of fossil-based fuels for energy has given rise to serious issues like environmental degradation and global warming. Replacement of petroleum-based fuels with biofuels, such as vegetable oils, biodiesels, etc. has drawn the attention of researchers in order to address the a fore-mentioned issues in recent years. The present experimental investigation aims to produce mixed biodiesel (MXBD) from a mixture of three non-edible oils, viz. jatropha, karanja, and mahua and its application in a compression ignition engine to study the engine performance and exhaust emission behaviors. Results showed that MXBD exhibited superior engine performance and emissions over diesel, jatropha biodiesel (JBD), karanja biodiesel (KBD), and mahua biodiesel (MBD). Brake thermal efficiency with MXBD was greater compared to diesel and other biodiesels, whereas brake specific energy consumption with MXBD was lesser than other biodiesels and a little more than diesel at all engine loads. CO, HC, and smoke emissions were lowest with MXBD compared to all other considered fuels at entire engine loads. NOx emissions with MXBD were found to be marginally higher than those with other test fuels. Thus, the present work establishes MXBD as a better alternate fuel option for diesel engines over JBD, KBD, and MBD in terms of both engine performance and exhaust emissions.

Electromagnetic forming (EMF) is a contactless forming process where electromagnetic forces are applied to achieve the required deformation. It is also called as a pulsed magnetic forming technology where the main driving force is Lorentz force. Generally, EMF is used to deform highly conductive materials where tubes or sheets are expanded or compressed and magnetic forces are used to shape or join or cut the materials. It is a high-speed, high-energy rate forming process. As it involves a high strain rate, therefore, with the use of it the forming limits of several materials can be extended. In this paper, the EMF processes are reviewed by considering the recent advancements in different applications of electromagnetic forming, which includes perforation of tubes, crimping of tubes for different applications, joining by forming of tubes for torsional applications, etc. The working principle of different electromagnetic manufacturing techniques is explained. Based on this survey, it is identified that the recent developments of the electromagnetic forming research show a wide range of industrial applications. It can be commercialized to have sustainable manufacturing technology.

This review paper includes different coating methods with different nanocoating material for enhancing the surface properties. Due to surface properties (wettability, surface contact angle, roughness, porosity, etc.) and thickness of nanocoating, heat transfer rate increases. Nucleate boiling heat transfer and critical heat flux are major factors which decides the heat transfer rate. So if these factors are controlled, then heat transfer rate automatically controlled. Future scope in this field is also presented in this paper. Coating methods, by which non-metal material coated on metal are also listed below.

Kalman filters are used for motion state estimation of an autonomous vehicle-trailer system, which can be utilized directly to motion control and autonomous navigation. The autonomous vehicle-trailer system consists of an autonomous vehicle and a passive trailer coupled to the vehicle by a trailer hitch. The vehicle-trailer system is equipped with the global positioning system (GPS), encoder-based odometry, and hitch angle sensors. A Simulink model is first developed for the system kinematics. The vehicle states are then estimated using extended Kalman filter (EKF) and unscented Kalman filter (UKF). Simulation results are compared and discussed based on the root mean square error (RMSE) and the simulation time. The results indicate that both EKF and UKF algorithms have very close RMSE for the position x and y, whereas the processing time is increased by 17.7% for the UKF.

In friction stir welding (FSW) process, material flow is the most important aspect which affect the mechanical properties and microstructure of the welded joints. The good plasticized material flow reduces the formation of defects in the welded joint. In the present study, a three-dimensional volume of fluid (VOF) model based on ANSYS 14.5 FE software package was developed to predict the effect of traverse speeds (i.e. 90, 132 and 180 mm/min) on material flow behaviour during FSW of low carbon steel. Stain and temperature-dependent material properties were incorporated in developed material flow model. It is observed that the tool traverse speed strongly influenced the mixing of plasticized material in FSW of low carbon steel. The velocity of material flow was reduced as the distance increases away from the rotating axis of the probe or weld zone. The velocity vector of plasticized material was different at different planes throughout the welded joint. The material in plane nearby the top surface exhibited the maximum velocity than the plane close to the bottom surface. Experiment was also carried out using tungsten carbide tool to validate the material flow model. The transient thermal profile obtained from FE analysis and experiment was agreed properly well for peak temperature with a maximum percentage error of 6.72%.

TiAl4V is used widely in aerospace and biomedical application due to its high specific strength and good bio-compatibility. Its poor tribological performance restricts usage for hip implant articulation. Various surface characteristics such as surface roughness and wettability affect the tribological behaviour of Ti6Al4V sliding. Surface texturing is the recent technique to modify the surface features and improve the wettability. This study aims to compare the wettability and coefficient of friction (CoF) of discrete and continuous texture under bio-lubricated condition. Dimple and crosshatch textures are fabricated using laser surface texturing (LST) technique. The geometrical parameters such as depth, pitch and area density have been kept the same. Wettability associated with both the textures are analysed by measuring surface contact angles using goniometer. Further, friction behaviour is evaluated for all the textured and non-textured surfaces under biological environment using reciprocating pin-on-disc tribometer. Results show a significant reduction in contact angle for crosshatch texture compared to dimple and non-textured surface. Also, both the texture reduced the friction by 24% compared to non-textured surface.

Heat input during welding is the controlling factor for weld bead geometry (bead width, reinforcement height, and depth of penetration). Heat input plays an important role to evaluate the quality of the joints. Present experimental investigation aims to determine the effect of heat input on weld bead geometry. Gas metal arc welding of creep strength enhanced ferritic (CSEF) steel P91 with filler wire ER90SB9 using pure argon gas has been done. It has been found out that with increasing heat input, depth of penetration increases. However, variation of bead width and reinforcement with heat input is not so much clear. Based on bead-on-plate experiment, heat input of 1.337 kJ/mm was recommended for joining of 6 mm thick P91 steel plate. For weldments characterization, optical macroscope, optical microscope, Vickers microhardness tester were used.

Nanoparticles (NPs) have drawn immense attention due to the full range of new applications in various fields of industries such as electronics, optical, biomedical, pharmaceutical and cosmetics. NPs gained importance due to their exceptional properties like antibacterial activity, high resistance to oxidation, exceptional adhesive properties, better thermal conductivity and many more. Various interdisciplinary researches have been done in the field and still going on. The aim of this paper is to briefly describe the details of NPs processing methods, their benefits and limitations and the need of new process in the field. In this paper, electrical discharge machining (EDM) has been presented as possible new process for the synthesis of NPs. The challenges in the development of EDM as a NPs synthesis process have also been discussed in this paper.

The process of laser cladding offers superior metallurgical and mechanical properties of the product. This is possible through the additive nature of the process but brings challenges in controlling the surface requirements and defects. The generation of thermal stresses in the cladding material as well as the substrate materials results in delamination and formation of a substantial crack in the remelted zone. One of the strategies followed to control the defect formation and also to manage the microstructure in the cladding material, preheating is often applied. Moreover, preheating also facilitates the localized melting of the cladding material over the substrate for better melting and remelting. In the current investigation, a laser source is simulated in COMSOL and two paths for preheating a cavity on stainless steel materials are used. The power of the laser source is kept fixed at 70 W and the other parameter like laser traverse speed and beam spot diameter has been fixed at 1.5 mm/s and 1 mm respectively. The numerical solution of the system of equations resulted in time–temperature information. Later, the heat transfer gradient is computed for the paths from the time–temperature information acquired through numerical simulation and the best one is selected to obtain a uniform heat distribution. The study revealed that the path which followed a circular pattern results in a better heat transfer gradient for effective preheating of the substrate material.

Synthesis of path generating four-bar mechanism is performed with the objective to minimize the error between generated and specified path points. The deterministic synthesis of mechanism determines the link dimensions without considering the effect of uncertainties. The deterministically synthesized mechanism will not perform as desired due to the uncertainties. Tolerance design has been performed to improve robustness of such mechanisms by allocating suitable link tolerances and joint clearances. The robustness of such mechanisms has been analyzed by Taguchi method. Thus, the robust design of mechanism has been performed in stages. In this paper, a methodology is presented for optimum robust synthesis of path generating four-bar mechanism. Differential evolution has been used as evolutionary algorithm for the synthesis. The methodology simultaneously optimizes link lengths and corresponding tolerances, along with joint clearances at both ends of coupler link. The modified geometry of four-bar mechanism considering link tolerances and joint clearances has also been discussed. The methodology has been applied for synthesis of four-bar mechanism for tracing a straight line path. It has been observed that the synthesized mechanism has the minimum objective function value. It has also been observed that the variation in objective function value due to uncertainties is minimum, as the standard deviation of objective function value is minimum. Thus, the methodology has resulted in robust path generating four-bar mechanism.

The demand for customized products slowly shifted the manufacturing industry from mass production to rapid prototyping or batch production that needed a new sheet forming technique. In recent years, the researchers pay attention to single point incremental forming (SPIF), an emerging sheet forming technique. It is a quite flexible sheet forming process which eliminates the dedicated die or punch. The surface quality of the finished product in SPIF is one of the domains because it is concerned with the customer's demand. The tool feed and variation in depth of deformation resembles in the finished product. For minimizing the waviness of the finished part, ANN-based modeling is done in the present study. A good agreement with experimental data and overall regression performance of ANN 98.99% and an acceptable error of −0.136 is found.

A maximum entropy formulation (MEF) has been applied to predict the droplet size distribution for a viscoelastic planar liquid sheet. A modified approach has been introduced in the formulation to solve the set of nonlinear equations which result in less computational time and increase probability of convergence of Newton–Raphson method. The effect of gas–liquid density ratio $$(\rho )$$ ( ρ ) also has been studied over the droplets size distribution at different gas–liquid velocity ratio $$(U)$$ ( U ) . Analysis shows that droplet size distribution becomes narrower and peak of the curve increases and shift towards the finer droplet size with increase in $$\rho$$ ρ and $$U$$ U .

A linear analysis of sinuous instabilities in a two-dimensional planar viscoelastic sheet subjected to two inviscid gas streams of equal non-zero velocities is performed. The rheological model of the viscoelastic sheet is considered to be corotational Jeffrey’s model. Perturbation technique is employed to obtain the linear governing equation and boundary conditions. Solution of the first-order dispersion equation yields the maximum growth rate and corresponding dominant wave number. Parametric investigation of the effects of elasticity number and time constant ratio is performed for different gas-to-liquid velocity ratios. Linear analysis predicts that elasticity number enhances the maximum growth rate. On the contrary, time constant ratio is observed to dampen the maximum growth rate. Hence, elasticity number and time constant ratio exhibit a destabilizing and stabilizing effect on the liquid sheet, respectively

Development of paper currency detection system is one kind of smart framework which is of significant requirement in today’s modern world. Currency recognition means denomination classification and counterfeit detection. There are many currencies all over the world. Every currency appears unique based on features such as variation in size, texture, colour etc. In the present study, a system is developed to reduce counterfeit detection time. Image processing and feature extraction technique in the presence of UV light are implemented for currency identification. Some of the features of real banknote are only visible in the presence of UV light. In case of Indian currencies, security thread looks green in presence of UV light. This study trains a feedforward backpropagation neural network with 20 samples of each denomination. The validation resulted 100% accuracy with reduced processing time for currency recognition and counterfeit detection.

The study presents the design and fabrication of the Android application-based robotic grass cutter. A smartphone is used as remote, and it is able to control the movement of four omni wheels to perform grass cutting operation with the smooth movement of the cutter installed on the system. This apparatus composed of five DC motors, two motor drivers, an Arduino board, a Bluetooth module and a battery. The DC motor aligned vertically, compounded with a blade, cuts the rough grass as the robot moves in a particular direction. Remaining four DC motors are connected to the four wheels of the robotic grass cutter vehicle providing three planar motion, i.e., motion along x-axis, y-axis and rotation about z-axis. The direction of rotation of these motors can be controlled by the Arduino board. The battery supplies power to the motors. Bluetooth module is used as a transmitter as well as a receiver to follow up the input/output signals from the Android phone to the Arduino board controller. As the mobile remote sends input data to the Arduino, the motors are driven accordingly by the motor drivers. Thus, the remote is able to move the grass cutter in all the directions in the plane like forward, backward, diagonal motion and can also turn around. The mobile-operated grass cutter presented here is a very convenient robotic device which is simple in assembly and construction. It is employed to maintain and conserve the lawns in gardens, schools and colleges etc. Design is intended to be simple and effective thereby making grass cutting inexpensive.

Boiling has got prominence in the recent decades for its effectiveness in cooling of micro-electronic devices due to its superior heat extraction ability as compared to air or single-phase liquid cooling. Numerous works have been published regarding augmentation of boiling heat transfer by developing modified surfaces. Micro- and nano-surfaces have been developed for this purpose. These surfaces are engineered either by surface coating or by micro-machining. The present review attempts to elaborate the various coating techniques and methods that have been used to fabricate surfaces to improve pool and flow boiling heat transfer. The experimental studies have been primarily focused in this paper. The results obtained using the modified surfaces and the mechanisms responsible for them have been discussed.

The intrinsic properties of particulate types of reinforcements such as isotropy, good machinability, withstanding capacity of high tensile, compressive, shear stresses make it suitable as a reinforcement in Aluminium metal matrix composites. This paper mainly discussed the different types of reinforcements such as TiC, Boron Carbide, Coconut shell powder, Aloe Vera powder, SiC which affects the mechanical properties such as yield strength, ultimate strength, fracture toughness, and tribological properties such as wear resistance of composite. It has been found that the harder ceramic particulate reinforcement enhances the ultimate tensile strength and hardness of the composite under the phenomenon of pilling of dislocations at the grain boundaries. Reduction in wear resistance due to softening of matrix material at higher loads has also been noticed in the literature. This study demonstrates that the Aluminium metal matrix composites can be treated as the superior materials for the design of automobile components such as piston and cylinder assembly and crank shafts which require high wear resistance and specific strength.

Solar energy may be considered as the most feasible renewable energy source with a wide range of applications in today’s world. A suitable energy storage medium, capable of storing and supplying this energy as per requirement provides for an effective thermal management of solar energy devices. Latent heat storage systems have gained significant attention from researchers and academicians due to its higher storage density and smaller temperature difference between storing and releasing heat as compared to sensible heat storage. This chapter attempts to summarize the previous work carried out in solar drying applications implementing phase change materials as latent heat energy storage medium. It is concluded that such materials are capable of reducing the heat losses associated with solar dryers and significantly increase its efficiency.

Wing manufacturing is one of the critical tasks in aerospace industry. Built-up-wing panel is manufactured by forming sheet blank into the desired shape using a stamping die. The design of a stamping die essentially begins with the geometric development of die-faces, which are forming interfaces of punch, die, and binder. Nevertheless, ensuing forming interface geometry is hardly possible right at the first time, and depending on the experience and skills of the methods engineer, several costly physical tryouts may be required to ensure a die-face design that deforms the blank into the required stamping part. Adding to this, the wing panel geometry is a complex 3D surface and uses maraging steel as the material which is an ultra-high strength steel, forming behavior of which is unknown to the industry. Therefore, it becomes very difficult to develop a stamping die which forms the desired part and also consumes relatively low process time and other valuable resources. Finite Element (FE) simulation of the process of sheet metal forming, on the other hand, shifts the costly press-shop try-outs to virtual environment and provides the essential information on material forming behavior, part formability, spring back deformation, forming process feasibility, etc. This information is useful in designing the forming interface of the die. In the present study, the plastic anisotropy parameters are determined based on the tensile tests and these values are used in the FE analysis. The study and analysis of the present design of die and the forming process are done and the results are presented. The FE analysis of the stamping process of maraging steel wing panel has been performed. Based on FE analysis, a new die-face design is suggested, and comparison of the present and the suggested forming processes are presented together with the conclusions.

We explore the heat transfer characteristics for forced convective flow of a Newtonian fluid through the wavy channel under the effect of non-uniform heat flux. The findings are presented for different values of Reynolds number (Re) and dimensionless wavelength of the non-uniform heating $$(\gamma)$$ ( γ ) in the range of 100 $$\le$$ ≤ Re $$\le$$ ≤ 500 and 0.25 $$\le\gamma\le$$ ≤ γ ≤ 4, respectively. The non-uniform heating decreases the hot spot intensity in the circulatory flow zone and moreover it induces additional maxima of Nusselt number as compared to the constant heating case. The average Nusselt number for sinusoidal heating case is much more than the constant heating case for the smaller undulation of the non-uniform heating.

Materials which are having high strength-to-weight ratio, high stiffness, hardness, and corrosion resistance should attain high priority in case of material selection for industrial applications, defense, and aerospace sectors. There are so many materials which are selected depending upon type of applications; they are super alloys, shape memory alloys, high entropy alloys, and composite materials. Among all, composite materials find major applications in automobile, military and aerospace, especially aluminum metal matrix composites are in demand because of its high strength-to-weight ratio and high corrosion resistance compared to other composite materials. In the present work, experimental investigation on aluminum (AA7075) hybrid composite with B4C (6%) and graphite (2%) as reinforcements by altering the sintering temperatures and their effect on mechanical properties of the composite material were studied. From the results, it was concluded that added graphite acts as binder material that helps in enhancement in strength of the composite material at high sintering temperatures and also by increasing the sintering temperatures mechanical properties of the composite material improves along with reducing porosity levels but beyond the critical sintering temperatures porosity levels increases that effects the composite material in negative way. From the results, it was concluded that added graphite acts as binder material that helps in enhancement in strength of the composite material at high sintering temperatures and also by increasing the sintering temperatures mechanical properties of the composite material improves along with reducing porosity levels but beyond the critical sintering temperatures porosity levels increases that effects the composite material in negative way.

Unsteady laminar natural convection within a square enclosure with wavy bottom wall embedded with a couple of circular cylinders placed in the vertically symmetric mid-plane is numerically investigated. Present study numerically quests for four different interspacings of the cylinders ranges $$0.1 \le S \le 0.4$$ 0.1 ≤ S ≤ 0.4 and for Rayleigh number (Ra) in the range of 103–106. The results are discussed based on distribution of isotherms, streamlines, and temporal distribution of surface-averaged Nusselt number (Nus) along with the time-averaged Nusselt number (Nut). The outcome of the investigation infers that heat transfer takes place solely due to conduction up to Ra = 103, whereas the heat transfer shifts the mode from conduction to convection with increase in Ra. Further, Nut is found to increase with increase in S at lower values of Ra. Moreover, for higher values of Ra, the variation of Nut evaluated at the surface of the cylinders shows contrasting features with changing cylinder spacing.

This paper aims at selecting the optimal parameters for drilling of graphene oxide/pineapple leaf filler-reinforced epoxy hybrid composite using ultrasonic machining (USM). The selection of optimal parameters has been done using the interactive multi-criteria decision-making (TODIM) method. The subsequent process parameters are kept constant: boron carbide abrasive, amplitude of vibration (3–5 µm), and frequency (20 kHz) and the other parameters abrasive grit size, abrasive flow rate, power rating, and slurry concentration are considered for evaluation. The corresponding response parameters viz material removal rate (MRR), tool wear rate (TWR), and overcut (OC) are measured for every experimental runs. Two different levels of abrasive grit size and four different levels of flow rate, power rating, and slurry concentration are selected for detailed experimentation. CRITIC method has been applied for assigning weights to the process parameters. By implementing the TODIM method, the highest rank of the parametric combinations of process parameters is found out which tends to maximize MRR and minimize TWR and OC.

In this study, optimization of planetary gearbox considering regular mechanical and critical tribological constraints such as wear and scuffing is done. The design variables considered are the number of teeth in the sun, planet, ring gear, module, face width, diameter of shafts, planet pin diameter, the hardness of gear material and kinematic viscosity of the oil. The two objective functions are the weight and total power loss of the planetary gearbox. The analysis is done for the unmodified gear tooth profile with various input power from 30 to 90 kW with an incremental of 30 kW at the input speed of 1000 rpm. The result of multi-objective optimization with tribological constraints is compared with the single objective optimization considering the weight of the gearbox as the objective with and without tribological constraints. The result obtained considering multi-objective optimization shows that there is a significant reduction in weight and power loss as compared to results obtained by considering single objective optimization with and without tribological constraints. Further, the risk of gear failure in wear is in moderate to high range when the tribological constraints are not considered.

A numerical analysis is conducted to examine the effect of non-uniform heating for forced convective flow through a circular microduct having finite wall thicknesses. Two different arrangements of applied heat flux in the form of stepwise constant are studied for two different wall thickness, Reynolds number in the range 20 ≤ Re ≤ 200 and for a given substrate material. The results in the form of temperature and Nusselt number are compared with that of the non-conjugate analysis and uniform heating strategy. The analysis suggests that the effect of wall thickness is significant for the analysis of forced convective heat transfer in microduct. Moreover, the arrangement of non-uniform heating should be such that lower heat-producing sources be at the entrance and followed by higher heat sources.

Micro electrical discharge milling (µED-milling) is gaining a tremendous reputation due to its capability of fabricating intricate shapes with a simple rotating tool. Its unique advantage of machining any electrically conductive material makes it applicable for processing high strength materials like titanium (Ti) and its alloys. The present study investigates µED-milling of Ti grade 2 alloy using tungsten carbide as a tool electrode. The effect of important process parameters like voltage and tool rotation speed (TRS) is examined by evaluating response measures such as material removal rate (MRR), tool wear rate (TWR) and electrode wear ratio (EWR). MRR and TWR increase with an increase in both voltage and TRS due to a rise in discharge energy and better flushing of eroded particles from the machining zone. Highest MRR of 268,232 µm3/s and lowest TWR of 27,845 µm3/s is achieved at highest (200 V and 2000 rpm) and lowest (110 V and 500 rpm) parametric combination, respectively, considered in this study. EWR decreases with an increase in voltage, whereas EWR has a negligible variation with an increase in TRS. The lowest EWR of 0.199 is achieved at a voltage of 200 V and TRS of 500 rpm.

Nowadays, plastics has become an integral part of the modern world. Its utilization in different fields is increasing rapidly because of its excellent “long-life” property. But the conventional plastics produced from non-renewable resources like coal, petroleum and natural gas need decades to degrade in nature. Biodegradable plastics or bio-plastics are form of plastics which are derived from plant resources and are “naturally” degraded. The present work investigates the extraction of the optimum quantity of starch and develops a method for producing bio plastic from yam (Dioscoreaalata). It also aims to access mechanical and physical properties of the starch-based plastic film. Tensile strength and percentage elongation plays important role in plastics use, so to prepare a plastic film that has good strength and which can elongate without fracture is desirable. Also, biodegradability test is evaluated in this work which is necessary for environment-friendly plastics. Optimum quantity of starch was extracted from a given quantity of yam by different processes like blending, filtration, drying. Preparation of plastic from starch overall follows a polymerization reaction but is divided into processes like plasticization, gelatinization, neutralization, heating, cooling. Hydrochloric acid and plasticizer (glycerol and sorbitol) play a vital role in plastic film preparation. Sodium Bicarbonate (NaHCO3) is used as preservative for the plastic after manufacturing.

Turning parameters for cutting DAC-10 tool steel was optimized using surface response methodology (RSM). Turning was performed with TiAlN coated single point tool bit on CNC lathe. Cutting speed, feed rate, and depth of cut were considered as the cutting parameters and relative effect of process parameters on surface roughness and tool wear rate was analyzed. Outcomes revealed that feed rate and cutting speed are the governing parameters for surface quality and cutting speed for tool wear rate respectively. Optimization method confirms reasonable zone for responses and gives optimal condition for turning with cutting speed 150 m/min, feed rate 0.1 mm/rev and depth of cut 0.4 mm.

Off-grid renewable energy systems have been fascinating to provide energy to different sectors in all the directions like sustainability, viability and environmental safe-conduct, particularly for the societies living in remote areas where expansion of grid is not relevant. Renewable energy system shows numerous combinations built on the basis of renewable sources that can be practiced together to provide power in the form of a dedicated off-grid system supported by battery-bank storage and diesel generator as backup systems. In this article, wind turbine-PV-battery storage-inverter was used as system components and these were simulated and optimized for the entire NIT Silchar campus in the state of Assam, India. The primary load demand of the entire campus is 11,378.94 kWh/day and peak load of 671.62 kW. A popular freeware HOMER modelling software has been used to analyze the stand-alone RES system. Solar energy and wind are used as prime sources to generate power and supply it straight to the load. If excess electricity is produced, it is used to charge the battery bank. The campus’s load consists of power required for lighting, pumping of water, hotel electricity load, different department electricity load and various quarters load which are situated inside the campus. While analyzing this energy system, the simulation is done and results are optimized on the basis of power load, meteorological data sources. The economics of energy components and other parameters in which the net present cost (NPC) is to be minimized to select an economically viable energy system. However, other criteria, such as additional power generation, capacity shortage, COE, were also acknowledged to investigate the technological ability to choose an excellent system in techno-economic perspectives. The two approaches are used as a comparative criterion to select an energy system from the chosen options that give sufficient merit to one of the measuring tools (Net present cost and low cost of energy).

Harvesting is a crucial activity of sugarcane production, which affects overall productivity. Timely harvest is very essential to achieve better quality and high yield, but shortage of labours during this time incurs major losses to farmers. Manual harvesting of sugarcane is a very labour-intensive and arduous activity, intervention of mechanical systems for harvesting frees harvest labours from drudgery and helps to improve productivity. Existing harvesting machinery is of huge size and is not suitable for Indian farming canopy and also not affordable to farmers with small landholdings. The proposed work was aimed at developing a low-cost mini sugarcane-harvesting machine, which has a very small footprint and a simple mechanism for cutting sugarcane at the base. Detailed design of the subsystems and components have been carried out to realize the final working prototype. The developed machine is capable of harvesting sugarcane with a single cut leaving partial to no edge damage on the cut surface. Different varieties of sugarcane of diameter up to 40 mm can be harvested with the developed harvester. The developed machine can also be employed for harvesting other similar crops with same cutter assembly or by using separate attachments. Cost and time of harvesting can be significantly reduced by employing the developed harvester, leading to increased productivity.

The present work is simulation and experimental performance analysis of a single cylinder spark ignition engine. The simulation model was prepared as a MATLAB code consisting of various input parameters like bore, stroke, compression ratio, spark angle, load, RPM, fuel–air equivalence ratio, inlet pressure, temperature, valve timings, etc. The model uses Wiebe’s heat release model, Annand’s heat transfer model and Blair’s friction model in order to predict the properties with respect to crank angle. Using these data, various performance parameters like brake power, brake thermal efficiency, torque and brake specific fuel consumption were determined by varying the engine speeds, equivalence ratios and loads. The results obtained by simulation were verified by an experimental analysis on a four-stroke single cylinder Honda GX200 computerized Spark Ignition engine. It was observed that the trends in variation of the performance parameters were similar for both the simulation and experimental data. Brake power, torque and brake thermal efficiency were higher in the simulation model whereas brake specific fuel consumption was higher for experimental data. Maximum values of brake power obtained were 2.33 kW for simulation and 1.85 kW for experiment both at 2780 RPM for an engine load of 2.1 kg. Maximum values of torque obtained were 7.35 N m for simulation and 6.35 N m for experiment both at 2780 RPM at an engine load of 2.1 kg. Maximum values of brake thermal efficiency were 13.8% for simulation and 11.3% for experiment both at 2769 RPM for engine load of 1.9 kg. Maximum values of brake specific fuel consumption were 1.92 kg/kWh for simulation and 2.8 kg/kWh for experiment both at 2874 RPM for an engine load of 0.5 kg.

Precision machining of the difficult to machine materials is the most challenging task of the present manufacturing industry. Rubber is one of the most commonly used materials and can be cut easily by conventional cutting process in macrolevel. But to perform precision machining and microfeatures on rubber is quite a difficult task for its well-known properties like elasticity and resilience. On the contrary, ultrasonic machine is making use of machining of tough and brittle materials. In this paper, drilling operation has been done in microlevels on rubber using ultrasonic machining. During experimentation, the influence of process parameters on the performance measures material removal rate (MRR), and overcut (OC) has been studied. After successful drilling in rubber material, it has been observed that diameter and MRR varies from 398 to 535 µm and 0.0053 to 0.0175 mm3/min, respectively, with a stainless steel tool of 550 µm in diameter.

Air pollution is rising day by day and it is a serious threat to society and the environment. One of the main reasons for air pollution is exhaust gas emission from automobiles and industries. To reduce air pollution from the exhaust emission a device is introduced called Aqua silencer. With the help of this air is purified from the pollutants such as Carbon monoxide, Unburnt Hydrocarbons, Oxides of Nitrogen, etc. and it also reduces the damping noise. In this present paper, designing, fabrication, and testing of modified aqua silencer for the diesel Genset are discussed. Moreover, testing was conducted for three different conditions of silencers and the result shows that the exhaust emission of the aqua silencer with and without lime water reduces considerably.

In the present study, the melting of phase change material (PCM) in a square enclosure with different wall heating conditions has been studied numerically. It has been found that at the early stage of melting, PCM melts faster in case of bottom wall heating. Melting for sidewall heating transcends the melting of bottom wall heating in a later stage. However, the increase of solid–liquid interface length leads to higher convective heat transfer for side wall heating in later part of melting. On the other hand, isothermal heating from the upper wall results in thermal stratification of PCM layers which leads to no convection. So, the melting time is quite large for this case.

In the present work, a numerical investigation has been performed to investigate the thermohydraulic performance of a circular pipe used in a heat exchanger with and without insertion of vortex generators. Vortex generators (VGs) which are used inside the pipe having dimensions of blockage ratio 0.3 and attack angle of 0°. The investigation has been carried out for Reynolds number (Re) ranges from 6000 to 24,000. Two cases of implementing vortex generators namely two VGs configuration and four VGs configuration have been investigated and compared with a smooth pipe which is of the same geometric parameters. Nusselt number (Nu) and friction factor (f) have been considered for representing the thermal and hydraulic characteristics, respectively. The overall performance of the two VGs and four VGs configuration has been calculated using the thermal performance enhancement factor (TPE). It has been found from the results that using VGs, heat transfer rate of smooth pipe can be improved while pressure drop also increased compared to the smooth pipe. With the increase in Re, Nu of all the cases increased with a significant decrement in friction factor (f). The overall performance in terms of TPE is maximum for four VG configuration at Reynolds number of 6000.

The effect of non-uniform heating on the heat transfer characteristics for electroosmotic flow through a microchannel has been investigated numerically. The temperature field and Nusselt number are studied by changing the normalized wavelength of non-uniform heat flux $$\left( \gamma \right)$$ γ and thermal Peclet number $$\left( {\text{Pe}} \right)$$ Pe in the range of $$1.5 \le \gamma \le 6$$ 1.5 ≤ γ ≤ 6 and $$1 \le {\text{Pe}} \le 100$$ 1 ≤ Pe ≤ 100 , respectively. It is found that the intensity of maximum temperature reduces for non-uniform heating as compared to the uniform heating. The maxima of local Nusselt number increases with a decrease in the wavelength of the non-uniform heat flux. The critical Peclet number $$\left( {{\text{Pe}}_{\text{c}} } \right)$$ Pe c is found such that average Nusselt number shows the monotonic and non-monotonic variation with $$\gamma$$ γ .

This paper presents the effect of temperature on random natural frequencies of spherical shells, composed of functionally graded materials (FGM) with zirconia (ceramic rich) and aluminium (metal rich). An eight noded isoperimetric quadratic element is considered for the finite element formulation. The power law is employed to construct the material modelling of Functionally Graded (FG) spherical shells. Monte Carlo Simulation (MCS) is carried out in conjunction to standard eigenvalue problems. The polynomial chaos expansion (PCE) model is constructed to reduce the computational iteration time and cost and validated it with the traditional MCS model. The statistical analyses are conducted to portray the first three random modes of frequencies. In the present analysis, the statistical results obtained are the first known results.

In the fast-changing world, the quest for the energy-efficient and environment-friendly processing method is getting attention while without compromising on the product properties, processing time and cost. Consequently, the processing of material with microwave energy is emerging as a novel method and it is used as an alternate processing route for various types of advanced materials like MMC, PMC and alloys for commercial applications in the field of joining, biomedical, powder metallurgy, coatings, claddings, etc. The microwave processing dominates over the conventional processing of materials due to its notable advantages like low processing time, less energy consumption, volumetric heating, negligible thermal gradient and better mechanical properties. The current study primarily focuses on microwave processing and its interaction phenomena with polymer, reinforced with different synthetic and natural fibers. It was observed that only electric field component of microwave is responsible for heating of PMC, due to its non-magnetic nature; the losses responsible for microwave heating like dipole and conduction further depend upon the type of reinforcements. It was found that the dipole loss mechanism predominates in natural fibers, while conduction loss is responsible in processing conductive fibers. A few initial results have been presented; future possibilities are indicated.

The velocity distribution in the axial direction of a conical fluidized bed is not uniform due to the expansion of cross-sectional area along the height. As such, the hydrodynamic and heat transfer characteristics of a tapered fluidized bed differ from that of the columnar fluidized bed. Various operating parameters have a significant effect on these characteristics. In this paper, the effect of bed inventory and airflow rate on the hydrodynamic and heat transfer characteristics in a columnar and conical are investigated and compared both experimentally and numerically. A Eulerian-Eulerian model is employed to investigate the hydrodynamics and heat transfer behaviour for both the types of bed. The Syamlal-O’Brien model is used as a drag model. The pressure drop across the bed is found to higher for the columnar bed. The heat transfer is also found to be better for the conical bed. Results obtained by experiments are seen to be excellent agreement with the numerical results.

Mild steel is one of the economical and widely used raw materials in engineering applications. The mild steel specimen could be easily fabricated using conventional arc welding, MMA welding, and gas welding process. TIG welding is one of the conventional welding techniques used in precision welding both for ferrous and nonferrous material. However, it is difficult and uneconomical to detect welding penetration and effect of the welding parameter through metallurgical analysis. Numerical analysis of welding process with the help of computational facility is economical with time saving. In this work, a finite elemental model has been developed to simulate the TIG welding process using bead on plate welding. The Gaussian heat model has been used to find the effect of welding current on weld pool geometry. The results showed that welding current has a maximum effect on weld pool’s temperature and geometry. Welding using high current produced high temperature in the weld pool, which leads to high penetration depth in the material. Similarly, the results of the numerical study also showed that with increase in current, the temperature at the center of mild steel increases.

A rotating fluidized bed with static geometry (RFB-SG) drying is a promising technique that is useful for various operations, such as agglomeration, food grain drying, particle coating, separation, and combustion. The advantage of this technique is that a large volume of hot air is circulated across the particles in a very small geometry, which results in higher heat and mass transfer. The higher heat and mass transfer through the RFB-SG dryer makes the drying process faster. Initially, the high-velocity air is injected into the vortex chamber through multi-air inlets, and then the solid particles are inserted into the vortex chamber. The high-velocity air injected into the reactor forces the solid particle to rotate in the form of a solid bed. The air entering into the vortex chamber carries away the moisture of food grains via a centrally located chimney outlet. In the present work, performance of scaled-up RFB-SG dryer has been evaluated considering parameters, such as temperature (55–65 °C), airflow rate (600–800 m3/h), inventory (400–1000 g), and drying time. The RFB-SG dryer is found to be more efficient than the conventional fluidized bed (CFB) dryers as this dryer works on a higher airflow rate. Drying efficiency is improved by better utilization of the drying air at a temperature of 65 °C.

Sun is supplying ample amount of solar energy throughout the day. But due to the intermittent nature of this solar energy, one storage is required. Sensible energy storage (SES) stores the heat energy during shining hours and supply that heat in the absence of solar energy. In the present study, an experimental work is carried out to observe the usability of sand as the SES material. Polycarbonate sheet is used as the glazing material and also acts as a container to storage material. The sheet is kept at different tilt angle (20°, 25°, 30°, 35°, and 40°) to observe the effect of inclination on energy stored in SES. Maximum global solar radiation is received during 11.00 AM to 11.30 AM. The maximum average temperature and energy stored in storage found when tilt angle is 30° due to receiving of higher solar radiation in that inclination. The average temperature and stored energy is lowest when SES placed at 20° tilt angle. Further, the conversion efficiency of SES is calculated for all the tilt angles. It is found that SES with 30° tilt angle provides maximum conversion efficiency around 20%, whereas efficiency is lowest at tilt angle 20°.

Biogas is mainly composed of methane (CH4) and carbon dioxide (CO2) with trace amounts of hydrogen sulfide (H2S), of which CO2 and H2S are impurities. Scrubbing of these two impurities are crucial for purification and upgradation of biogas, which would simultaneously also increase the calorific value of the treated biogas and address the issue of corrosion. Several studies have used expensive and environmentally harmful chemicals for the purification of biogas. This study reports a simple biogas purification system that utilizes biomass biochar and biochar–clay composites to remove CO2 and H2S from biogas by the process of adsorption. The biomass biochar could enrich the methane content of raw biogas from 59.7 to 84.6%, which shows the potentiality and applicability of biomass biochar for the removal of CO2 and H2S from biogas. This simultaneously enhanced the calorific value of the biogas and retarded the corrosiveness due to H2S. The study also indicated that CO2 adsorption by biomass biochar and biochar–clay composite is transient and has to be reloaded after saturation. Biochar and clay have the added advantage of being environment friendly and require no treatment for disposal. Observed results indicated that similar degree of enrichment, compared to commonly used chemical, could be achieved by application of biomass biochar and biochar–clay at a much lesser cost.

Tea has become an important crop in a many regions of the world. India is one of the best quality tea producers in the world. Despite of being an important cash crop, much research has not been made on tea, due to which modern drying technologies have not been employed in this regard. This work reflects the drying characteristics for tea in a bubbling conical bed dryer. Fresh Assam tea leaves have been processed into crush, tear, and curl (CTC) tea initially, followed by fermentation and drying in a conical bubbling fluidized bed dryer. The effect of various parameters, such as drying air temperature, superficial air velocity, inventory, and cone angle, on moisture removal rate from CTC tea in the conical bed dryer has been experimentally investigated and analyzed in this present work. Drying temperature and superficial air velocity are found to be the major parameter that affects the moisture removal rate from tea. The moisture removal rate from tea varies proportionally with the increase in drying temperature, but the quality deteriorates after a certain limit of temperature. Different cone angles of 0°, 5°, and 10° for the conical bubbling fluidized bed dryer are also inquired into for a static inventory bed height of 15 cm. It is found that moisture removal rate is highest for the case 10° cone angle of the dryer.

This paper demonstrates a working model of a 4PP (prismatic–prismatic) positioning stage where four sliders in the fixed base are associated with shape memory alloy (SMA) spring actuation individually. The end-effector of the robotic system developed has two degrees of freedom, i.e., translational in X- and Y-axis, respectively. The forward and backward movement of the developed platform is accomplished by coupling two sliders with the association of the SMA linear actuators. This model has a fixed part (the wooden base) and a movable part (end-effector). As the Nitinol SMA spring is lightweight in construction and has precise actuation, it has a wide range of applications over the other XY motion platform. Due to the deflection in the springs, the end-effector moves in both X- and Y-axis where the actuation of the SMA springs are studied with respect to the direction, and the workspace study is carried out. After the study, the comparison is done with the designed workspace. It is noted that this 4PP positioning stage has a precise actuation of springs due to the shape memory effect and provides a good workspace. Thus, it has a wide range of use in biomedical and optical applications where the motion stages are the primary requirement.

Photochemical machining (PCM) is one of the non-conventional machining processes that produces stress-free and burr-free components. It can be employed as micromachining manufacturing process to produce microsized components. This paper focuses on the selective etching of aluminium 6068 alloy using ferric chloride as an etchant. The primary aim of present work is to perform selective etching with greater accuracy. The input parameters/control parameters considered are etchant concentration, etching time and etching temperature. The performance measures have been chosen as material removal rate (MRR), edge deviation and undercut. The photochemical machining of aluminium has been carried out based on Taguchi L9 orthogonal array.

Joining with friction stir welding (FSW) of high-strength material is challenging work due to high tool wear/degradation and low tool life. Recently, developed tool WC–Co tool materials that withstand high temperatures and torsional stresses are used for welding of high-strength materials with FSW. In this article, friction stir welding (FSW) of Inconel plates is performed with WC–Co tool. The rotational speed of 300 rpm and a traverse speed of 90 mm/min were taken. In microstructural analysis, refinement of grain size of the base material (48 μm) to stir zone (18 μm) was observed, which results in enhancement of mechanical properties such as strength of the welded sample observed 77% of the base material strength, which shows partial welding of Inconel plate occurred and microhardness of the welded sample was 60% harder than base material hardness. FESEM of fractured tensile specimen informed the ductile fracture. Because of the high strength of Inconel alloy, after single weld, significant tool wear was observed. The EDS analysis was carried out at the stir zone of the weld, and it shows the presence of tungsten in the welded region, and also the presence of the Ni, Fe, Cr and Nb elements are found higher peaks in the EDS spectrum.

The paper presents the study of phase change material for the cooling of electronic components. The phase change material (PCM) used in the study is eicosane. Thermal conductivity enhancers (TCEs), made of aluminum, are used in order to alter the low thermal conductive nature of PCM. The TCEs are divided into no fin heat sink, constant height plate heat sink, and dual-height plate heat sink. Three power inputs of 4, 6, and 8 W are used for the study. Thermal cooling capacity by all the three heat sinks setups is compared. The effect of parameters such as power input and volume of PCM is also discussed. Results indicate that the power input level and the volume of PCM are important factors that influence the thermal management of electronic components. The use of 5 dual-height plate fin heat sink elongates the charging period of the PCM filled setup, thereby maintaining the device temperature within a favorable limit for a longer duration, as compared to the no fin heat sink and 5 constant height plate fin heat sink.

In this present work, the dynamics of a piezoelectric energy harvester consisting of two vertical cantilever beams with tip mass and piezoelectric patch has been studied. The beams are coupled with a linear spring and the system is subjected to base excitation. Both of the beams are identical except length and tip mass. Tip masses are attached in such a way that the natural frequencies of the beams come closer to each other which helps both the beams to resonate with principal parametric resonance condition. It is assumed that the beams undergo large amplitude oscillations, hence geometric and inertial nonlinearities have been taken into account. Considering Euler–Bernoulli beam assumptions, the nonlinear electromechanical equations of motion have been obtained by using Lagrange’s principle which is discretized to its temporal form by generalized Galerkin’s method. Using 4th order Runge–Kutta method, these governing equations of motion have been solved. Method of multiple scales has also been used to obtain the approximate response and voltages in the beams. It has been observed that in the pre-buckling regime, with increase in load resistance, the output voltages and the output power of both the beams increase. While the load resistance has no effect on system frequency. It has also been observed that with increase in stiffness of coupled spring, output voltages and output power of both the beams increase. Also it can be observed that with increase in stiffness of the coupled spring, at lower frequency power can be generated.

WEDM is not a traditional machining process. The process is based on a thermo-electrical energy system. In this process, any mechanical connection between the electrode (wire) and the workpiece is not required for cutting any object. To establish a contact within the wire and the work object, different dielectric fluids are used. Generally, this approach refers only to conductive materials (such as silver, copper, iron, brass, bronze). Once the deionized water flows, metal ions are released from the workpiece, and electrons are released from the wire and formed a spark between the wire and workpiece. The range of the temperature produced due to this action lies in between 8000 ℃ and 12,000 ℃. Due to this reason, the material is removed from the substrate. This article is about the investigation of the previous research work done on the different deionized water and its effect on the different output parameters acquired. From this study, researchers will be equipped with the summarized way to how to select the input parameters and enhance the output parameters using deionized water in the WEDM machining process.

Fuel injection strategy has become the heart of modern diesel engine due to its better commend on combustion process which ensures improvement in performance (BSFC, torque) and combustion noise (CN) with simultaneous reduction of emissions. In this experimental research work, impact of quadruple (epMa), triple (pMa) and double (pM) injection strategies have been studied on a typical six cylinder low-temperature combustion (LTC) CRDI diesel engine. Experiments were conducted at five different speeds (low to high) and three engine load conditions (20%, 60% and 100% of maximum torque, respectively) with higher EGR fraction of 45% and fixed main injection timing (Crank angle) using conventional diesel (BS-IV) fuel. The comparative study shown that quadruple (epMa) injection strategy is superior to provide optimum (BSFC, overall emissions) results in comparison with triple and double injection strategies for all aspects. Smoke level is marginally higher at lower-speed range for quadruple injection scheduling, whereas NOx emission level is the lowest among the injection strategies. Quadruple injection is capable of reducing combustion noise around 2–3 dBA at low loads and speeds over other two injection strategies.

This paper presents the first-ply failure analysis of laminated composite spherical shells by using the finite element method (FEM) in conjunction with Monte Carlo Simulation (MCS) approach. The material and geometric uncertainties caused by anisotropy and randomness inherent in the system configuration are predetermined in such structures and demand the stochastic analysis for realistic design. Finite element formulation is used to derive eight-noded iso-parametric quadratic elements. The input parameters include the ply orientation angle, assembly of ply, the number of layers, ply thickness and degree of orthotropy. The five failure criteria are considered, viz. maximum strain, maximum stress, Tsai-Hill, Tsai-Wu-Hahn and Tsai-Hill Hoffman theories. The variations in first-ply failure load are analysed. A deterministic study is carried out for the analyses of first-ply failure loads with respect to the mentioned failure criteria. The stochastic analysis is carried out firstly by the MCS approach. It is followed by implementation of the surrogate model. Radial basis function (RBF) is incorporated as the surrogate model. The current study predicts that the RBF surrogate model can be utilized to achieve similar computational efficiency with a significant reduction in computational time.

A286 superalloy is a Fe–Ni-based superalloy is widely applicable in superchargers, gas turbines, jet engines, fasteners, after burner and turbine wheels because of its innate properties like high thermal resistance, high mechanical strength and substantial corrosion resistance. This study is particularly devoted to suggest optimal process parameter settings for this superalloy, where the dimensional deviation becomes minimum value after wire EDM cut. Measurement of dimensional deviation (DD) is important as it suggests the practitioners to set a proper wire offset during the CNC programming of wire tool path so that the dimension of the product after the Wire EDM cut and the required dimension of the product matches properly. Five important parameters such as pulse on time (Ton), pulse off time (Toff), peak current (Ipeak), wire feed rate (Wf) and spark gap set voltage (SV) are controlled during the experiments, and the experimental layout is designed by L27 orthogonal array. Taguchi method in conjunction with ANOVA is adopted to obtain the significant control parameters. Parametric effect of the control factors on the dimensional deviation is explained. Furthermore, the optimal levels of the control factors are recommended based on higher signal-to-noise ratio values. Comparison between the experimental and the predicted values is evaluated to show reproducibility.

Fabrications of arrayed microrods using microelectrical discharge machining (EDM) are widely employed for drilling of multiple as well as arrays of microholes. It is commonly used in various applications such as perforated shadow mask, semiconductor device, and microheat exchanger. In the present work, gray relational analysis (GRA) has been proposed to optimize the multi-response performance characteristics (i.e., machining time and tool wear rate) of the process. GRA methodology is applied to optimize fabrication process of arrayed microrods to obtain the better dimensional accuracy with minimum tool wear and machining time using reverse micro-EDM (R-µEDM) process, a variant of micro-EDM process. In micro-EDM, tool wear and machining time are directly influence the dimensional accuracy of the microrods. The dimensional accuracy can be improved by reducing the tool wear and machining time during the fabrication process. The experimental investigation considers voltage, capacitance, and feed rate as input parameters. GRA optimization result shows that voltage of 150 V; feed rate of 25 µm/s; and capacitance of 10,000 pF are found as the optimum process parameters. The capacitance contributes 26.07% being highly influenced, followed by voltage (24.20%) and feed rate (5.17%). Voltage and capacitance have the statistical significance of 95% confidence level on overall performance toward the response parameters for getting the better dimensional accuracy with minimum time duration.

A bevel gearbox is complicated in geometry and founds application where the shafts are perpendicular such as helicopter and automobiles. Unlike spur gears, three forces exert on bevel gears to transmit the motion. Due to complicated geometry of gears, nonlinear and nonstationary vibrations excited due to meshing exhibiting severe modulations in the gearbox vibration signals. Delay in detection of faults could be fatal; therefore, the condition monitoring and early fault detection techniques are of vital significance. In the present manuscript, a novel signal processing-based approach has been presented to detect the gear faults under varying speed conditions. The vibration signals acquired from the test bench were decomposed using variational mode decomposition (VMD) and the sensitive sub-band is selected upon estimating the instantaneous frequency (IF). The selected mode function (MF) upon decomposition is analyzed using the statistical condition indicators and its FFT is developed. The FFT of the selected mode exhibits the symptoms of the gear faults.

Straight-blade vertical axis wind turbines (VAWT) have the ability to exhibit self-starting features and improved aerodynamic performance in the built environment for significant wind speed conditions. But in low wind speeds, such turbines realize several constraints for improved performance in terms of various parameters like blade design, blade shape, solidity, tip speed ratio (TSR), thickness-to-chord ratio and others. Therefore, the motivation behind the present work is the need for performance improvement of H-Darrieus VAWT in the built environment, which has characteristically low wind speed. Cavity shapes on the airfoil surface might cause local flow acceleration leading to suppression of boundary layer separation, which might enhance VAWT’s aerodynamic performance. In this paper, an attempt is made to investigate the effect of circular cavity shape on VAWT’s aerodynamic performance. Cavities have been formed on NACA 0021 airfoil based H-Darrieus VAWT. A CFD study is carried out to understand the inherent flow physics of the turbine. Results showed that there is a significant improvement in starting characteristic of the turbine at wind speeds 5 and 6 m/s having cavity on pressure side. The optimal tip speed ratio for the H-Darrieus turbine has been obtained as 1.3 for which the considered NACA 0021 blade turbine shows maximum power coefficient of 0.16.

The evolution of the yield surface, as predicted by a polycrystal plasticity model of a face-centered cubic material, is studied. Grains in the model polycrystal are endowed with a classical hardening law, which accounts for interaction among the slip system through a hardening matrix. In the literature, the elements of the hardening matrix are assumed non-negative. In the present work, the effect of negative elements in the hardening matrix on the evolution of the yield function, particularly, during monotonic tensile and shear deformation, is systematically studied. In particular, it is shown that certain parametric values simulate a substantial kinematic hardening, similar to experimental observations. The greatest kinematic hardening is obtained when the latent hardening ratio of the reverse slip systems is taken to be −1.2.

The aerodynamic performance of airfoil is certainly measured by the lift to drag ratio of that profile. In this paper, different NACA 4-digit airfoils are considered to perform the comparative analysis. The effects of camber ratio and thickness ratio on the aerodynamic coefficients are discussed. QBlade is used to calculate the lift coefficient and lift to drag ratio of each profile. Low Reynolds number (Re) of 3.6 × 105 is used for the present analysis. The angle of attack is varied from 0 to 20° to observe its influence on the aerodynamic performances. It has been seen that the lift coefficient increases with the increase in camber ratio of airfoil which implies more gain in lift force. Simultaneously, drag force also increases with increase in camber ratio. Therefore, lift to drag ratio has been calculated at different angle of attack for various cambered airfoil. Similarly, influence of thickness ratio is also studied, and it is observed that airfoil with lower thickness ratio produces higher lift to drag ratio at lower angle of attack (α ≤ 8°). Whereas, airfoil with higher thickness ratio produces maximum lift to drag ratio at higher angle of attack.

In this work, a modified cyclic plasticity model for FEM analysis of SA333 C–Mn steel has been developed. A memory stress based isotropic formulation is integrated into the modified Ohno-Wang model to revamp its nonmasing and hardening/softening characteristics. Accurate estimation of stress–strain hysteresis loops is a prerequisite for performing fatigue life analysis. The inbuilt classical cyclic plasticity model available in commercial FE software cannot precisely describe the material behavior. The proposed model has been implemented by using user-defined material (UMAT) subroutine with FORTRAN code on the ABAQUS platform. To evaluate the material constants for the proposed model, a set of experiments has been carried out under uniaxial loading condition. The same material constants are used for predicting simulation response for other loading conditions. To verify the proposed model, the simulation results are compared with experimental results which reveal good agreement under uniaxial loading condition

Kevlar fabrics have good energy absorption capacity and are widely used in defence, sports, and in impact resistance applications. To further improve these impact properties, materials such as shear thickening fluid (STF) could be used as they are believed to increase the composite’s impact resisting property due to an increase in frictional interaction. The present work involves the simulation of impact studies of the Kevlar fabrics with and without STF. The modelling is done through LS-Dyna which is a multipurpose software and analysis is carried out for different number of Kevlar fabrics of size 150 mm × 150 mm with edges being fixed. Ballistic limits, residual velocities and energy absorption of these fabrics are obtained for different velocities ranging from 50 to 150 m/s. These results are compared with the experimental values obtained through a single-stage air gun an in house setup developed by us. The numerical values show good agreement with the experimental values and effect of STF on energy absorption is also studied and it is seen that there is improvement in energy absorption and ballistic limit which is observed both in numerical studies as well as in experiments.

Polymer outdoor insulators are widely replacing the conventional ceramic and porcelain insulators due to their compelling properties. This work, studies and compares the mechanical performance of an elastomer matrix, nano and micro filler reinforced, thermoset composite, EPDM Silicone rubber filled with Garamite nano clay and Micro Silica/Alumina Trihydrate, for their applicability as an outdoor insulator. The base composition used for the study is a 50–50 Ethylene Propylene Diene Monomer (EPDM) and Silicone rubber blend. The compatibilizer used in this study is Vinyl Trimethoxy Silane. The strength and weight are important parameters which are looked at, while choosing the material for the outdoor insulator application. Organic nanofillers due to their compact packing have been observed to improve the strength of rubber composites to a great extent even when added in small proportions. This paper discusses the variation in strength of the composite with varying concentrations of Garamite (organic nanoclay). Also, to understand its effect on composite, the concentrations of micro fillers such as Alumina Trihydrate and Fumed Micro Silica which yield comparable strength to that of Garamite are studied. The study reveals that there is not much variation in strength between ATH and Micro Silica fillers, while a distinct difference in strength is observed in the case of the composite with Garamite.

With the advent of new technology in the manufacturing sector, the demand for micro products has been increased considerably. Having unique mechanical properties, glass has widespread application in the fabrication of micro products, but machining of glass at the micro-level, without any structural change is a challenging task. This work mainly emphasizes on slot-cutting/slotting of glass using ultrasonic machining. A stainless-steel tool of dimensions (12 mm × 8 mm × 0.6 mm) has been prepared and attached with a tool holder by the gas welding process and is used for slot cutting on a glass slide. The work also focuses on the effect of feed rate, power rating, and grit size on overcut, and edge deviation of the slot cut glass slide.

The surveillance and cleaning of the cooling pipes in nuclear power plants is a tedious task, as these pipes are dimensionally huge and submerged under the sea. In this paper, we present the design process of a modular underwater remotely operated vehicle (ROV) for surveillance and cleaning purposes of the cooling pipelines at Nuclear Power Plant. We divided the design into five sections: structure, propulsion system, electronic system, illumination system and modular attachments. The iterative design process includes computer-aided design (CAD), finite elements analysis (FEA) and, computational fluid dynamics (CFD). We have tried to make the design modular while keeping the basic structure of ROV the same. This will save the costs of using different ROVs for different tasks while making the control easier as each of these modules will have their power supply and electronics and will only receive instructions from the parent ROV. Also, there are many ROVs available in the market that are being used for the surveillance purpose so here our objective is to use the materials and systems with minimal cost to make the design cost-effective for the purpose required.

The present large eddy simulation (LES) study investigates heat transfer characteristics of a turbulent slot jet impingement on a smooth and flat target plate at a constant wall heat flux condition. The operating parameters are slot width (S) = 2.5 mm, nozzle to plate spacing (H/ $$D_{h}$$ D h ) = 4, 8, 12 and Reynolds number (Re) = 4000, 8000, 12,000. The results show that Nusselt number (Nu) increases with an increase in Reynolds number. The results also show at a fixed nozzle to plate spacing, on increasing the Reynolds number, Nusselt number (Nu) will also increase. The results also show that at a fixed Reynolds number, on increasing the nozzle to plate spacing, Nusselt number will decrease. The Nusselt number will be highest at stagnation point and then it gets decreased along wall jet regions.

The present numerical study is carried out to understand the film cooling characteristics of supersonic flow over a flat plate. The numerical investigation is carried out for the main stream Mach no. Mα of 2.67, secondary stream (coolant stream) Mach no. MC 0.05 and injection angle of 90°. The domain size is (x/s = 277, y/s = 22.8, z/s = 11.4) where ‘s’ is the slot width. The governing equations such as continuity, momentum and energy are solved using Ansys Fluent 18.1. Air is considered as working fluid for both main as well as secondary stream. The numerical results obtained using the LES modelling are validated with available Direct Numerical Simulation (DNS) results. The comparison of different LES Sub-grid scale models has been shown for providing standards for this type of problem.

This article describes the deposition of material onto the surfaces of the carbon fiber reinforced polymers (CFRP) material. For this purpose, powder metallurgical (P/M) green compact tool of tungsten-copper (W–Cu) particle is used in Electro Discharge Machining (EDM) process. The metal particles of P/M compact tool are transferred to the CFRP work surface under the reverse polarity. The material transfer rate (MTR) and tool wear rate (TWR) are observed by varying the process parameters (compact load, current, pulse on-time) in the suitable machining range. Grey relational analysis (GRA) is performed to determine the multi-objective optimal setting. Analysis of variance (ANOVA) and effect of factors in grey relational grade are conducted to determine the contribution of each factor to the multi optimal level. The experimental result shows that the multi optimum setting is obtained at compact load of 5 tons, current of 6A and pulse on-time of 1000 µs. Current is the most dominant factor whereas, pulse on-time is least dominant factor in multi optimal setting.

Utilization of wind energy has become an emerging concept for clean energy generation due to its vast availability, low cost and its contribution to carbon dioxide reduction. Wind turbines are the prominent converter which are used in both onshore and offshore wind energy generation projects. The performance of the wind turbines manly depends on blade aerodynamic performance. The aerodynamic performance of blade can be enhanced by using flaps, vortex generator, airfoil modification on leading or trailing edge, slots in airfoils, etc. The present paper mainly focuses on different passive flow control techniques, especially Gurney flap and vortex generator are used for enhancing blade aerodynamic performance.

Parametric study of Photo Chemical Machining (PCM) is necessary to obtain excellent etching quality. It can be used to reduce weight of a component, hence it can improve strength to weight ratio of a component. In the current study, the effect of control variables such as etching time, etching temperature, and etchant concentration on material removal rate (MRR), surface roughness and undercut in PCM of Stainless Steel AISI (SS-430) has been investigated. Taguchi L-16 orthogonal array has been designed to conduct the experimental runs. Moreover, the analysis of variance (ANOVA) technique is used to evaluate the significance of control parameters and also percentage contribution of input parameters. From ANOVA table, it can be observed that temperature is highly influencing parameter for MRR and undercut; whereas time is for surface roughness.

The aim of the present work is to fabricate and strength analysis of pure ramie fabric/epoxy composite and its hybrids ramie-glass/epoxy and ramie-basalt/epoxy composites. Hand layup technique has been used for fabrication of all the composites. Tensile and three-point bending tests have been performed to obtain the tensile strength and flexural properties of the composites. Morphological studies have also been performed on the flexural specimen to investigate the defects in the composite. The present study reveals that hybridization of natural fiber (ramie) with synthetic fiber (glass) and mineral fiber (basalt) exhibits higher mechanical properties than pure ramie composite. It has also been observed that ramie-glass hybrid composite has higher tensile strength than ramie-basalt hybrid composite. Scanning electron microscope (SEM) has been used to find out the defects in the flexural specimen. It has been observed from the SEM images that less number of defect present in hybrid composites than pure ramie fabric composite. Therefore, it could be concluded that the inclusion of advanced fabric at the external layers of the natural fiber composite would enhance the strength of natural composites.

In the present work, phase change material (paraffin wax) integrated double glazed rectangular finned solar air heater is investigated numerically using implicit discretization scheme. A MATLAB code is developed, capable of providing the solution for unsteady governing energy equations for each element of solar air heater and air flow. Numerical results are validated with published experimental results of a flat absorber plate collector design with PCM (Moradi et al. in Exp Thermal Fluid Sci 89:41–49, 2017 [1]). The idea of integration of PCM and fins with solar air heater is to provide thermal energy backup during off-sunshine hours and increase heat discharging rate of PCM, respectively. The average incident global radiation is the function of time and maximum incident radiation is taken as 960 W/m2. Moreover, a correlation is developed to predict the ambient temperature as reported in Moradi et al. (Exp Thermal Fluid Sci 89:41–49, 2017 [1]) as a function of time. The results showed that the thermal backup of PCM lasted for about 12 h after sunset almost for all selected numbers of fins. The maximum outlet air temperature for 5, 15 and 25 fins is obtained as 42 ℃, 47.16 ℃ and 51.25 ℃, respectively, at mass flow rate of 0.0128 kg/s. Whereas, the maximum instant thermal efficiency for 5, 15, and 25 fins is obtained as 35.867%, 49.375%, and 58.198%, respectively.

Aluminium alloys are known for their very good strength to weight ratio. Aluminium alloy finds its applications depending upon the alloying agent/agents added. Among other alloying materials Copper, Silicon, Magnesium are some of the alloying agents which are largely used with Aluminium, as they improve the strength of the alloy without affecting the density when compared to pure Aluminium. Addition of Silicon to pure Aluminium improves the strength of the resulting alloy at room temperature. But at higher temperatures (above 150 ℃) strength of Aluminium–Silicon (Al–Si) alloy is very poor. It is a preferred alloying agent when it comes to casting as the Al–Si alloy shows good casting ability compared to other (alloy without having silicon). But in the present study Copper is used with Aluminium as the major alloying material and silicon is either absent or present only as impurity. Copper addition to the Aluminium improves the alloy strength at room as well as at high temperatures, but at the cost of quality of the cast component. To get good quality, defect-free castings and to improve yield ‘casting simulation software’ can be used which can predict the casting defects virtually. So in the present study effect of adding Copper in the absence of silicon is studied where casting simulation software helped to predict the solidification time and quality of final cast component. Prediction of solidification time for different compositions of alloy gives an idea about the hardness of the alloy. Simulation results from two types of sand castings (spiral shape, step) are compared for their solidification time. The variation in solidification time with variation of copper weight percentage which is 4, 8, 12% for this experiment is studied. It was found that for a fixed composition the solidification results from both types of sand casting (spiral shape and five-step component) are of similar nature. The shop floor casting of the five step component is done and Rockwall hardness for all three compositions tested. Prediction of solidification time and shrinkage defects results obtained through virtual casting process helps in improving process parameters which eventually can help in improving the yield of the component production. Hardness results obtained for different compositions goes well with the type of predicted solidification nature (time) for different shapes of casting for this study.

Superior properties such as stability at higher temperatures and corrosion resistance make nickel-based super alloys to use in aviation, marine, and processing industries. However, properties like chemical attraction and low thermal conductivity keep these super alloys under difficult to machine materials. In such cases, EDM is the one of best possible solutions to machine electrically conductive materials. It is difficult to achieve smooth surfaces and more material removal rate (MRR) using normal EDM due to instability in the process. To achieve better MRR and surface roughness (SR), silicon carbide (SiC) powders has been mixed in the dielectric fluid to study the effects of current, powder concentration, pulse on time, and pulse off time. Results indicated that 49.09% increment in MRR, 29.22% increment in surface finish, and better microstructure has been achieved by powder-mixed electro discharge machining when compared to the EDM with simple dielectric.

The current cooling demand and the size of the microchannel sink make it very much challenging for the removal of heat in modern electronics compact components. The heat sinks with simple smooth microchannels are not adequate to remove the required heat nowadays. Uses of rib, cavity, dimple, protrusions on channel wall are the techniques to improve the Nusselt number (Nu), thermal resistance which signify better performance of the heat sink. A significant number of works on single-layered microchannel heat sink are carried out and after the proposal of new concept of double-layered heat sink for the purpose of cooling of the electronic devices, works on this type of sink are also started due to its high prospect. Silicon and water as the substrate material and coolant, respectively, are the choices of most of the researchers due to the merits they have. The present work is a review of the available literatures and research papers relevant to microchannels having different geometry structures with the objective to find and analyze the effects of the channel geometry on the enhancement of performance of microchannels.

Phase change material (PCM) can be utilized for thermal energy storage, where extra or waste heat is available. Extra heat generation is dangerous for various systems like electronics equipment, Solar panel, Li-ion battery, etc. that can reduce the efficiency or damage the systems. So, with the incorporation of PCM one can manage that extra heat. PCM can also store the available solar energy which may be utilized for solar water heating systems, solar stills, solar air heater, etc. In the current study, beeswax is used as PCM and graphite used as property enhancer. The fabrications of composite PCM have been done with melt-mixing method. Scanning electronic microscope (SEM) and X-ray diffractometer (XRD) were used to obtain morphology and chemical compatibility of the composite. Differential scanning calorimeter (DSC) and thermal conductivity meter were indicated the melting temperature, melting latent heat, and thermal conductivity of the sample. SEM and XRD results revealed that the fabricated composite was only the physical combination of BW and graphite there is no extra chemical form during the combination. The DSC data indicated that melting temperature values were decreased from 61 to 58.5 °C at the same time latent heat also decreased from 160 J/g to 141 J/g. Thermal conductivity result showed that the value of conductivity increased from 0.25 to 0.76 W/m–K. All the results favored that the developed composite can be utilized for water heating units.

To enhance the heat transfer performance, the advanced design of the equipment is essential as it can save energy, material, and cost. Among many techniques for the enhancement of the heat transfer rate, disturbance formation in the form of the roughness at the heated surface is suitable. This idea generally leads to generate turbulence. Ribs can highly be recommended for the placement on the heated surface to increase the heat transfer rate. The roughness in the form of ribs can be used in numerous applications such as solar air heater, gas turbine blade cooling, and nuclear reactors cooling, etc. Rough surface in the form of ribs create the disturbance in the laminar sub-layer. It leads to the increase in turbulence near the heated walls and this turned in to the enhancement of the heat transfer rate. However, rib roughness on the heated surface increases the flow resistance. So, this is the challenge to design a novel shape and configuration of ribs. The ribs should also be designed in the direction of enhancement of the heat transfer rate with the least pressure drop penalty. So, the objective of the article is to comprehend and explore the traditions behind the numerous design of ribs and their effect on the heat transfer rate. In recent years, a combination of more than one method to enhance the heat transfer are used simultaneously to achieve required heat transfer enhancement. The quest to enhance the heat transfer with a lesser drop in pressure by modification of heated surface is still a topic of research. So, there can be chances to enhance the heat transfer rate by using a novel design of ribs roughness. Lower heat transfer has been seen between the wall and the air because of the lower air heat transfer coefficient. Therefore, investigation on the heat transfer enhancement technique is still a research area when working fluid is air. It is also noticed that researchers have mainly used single shaped ribs, but combination of different shapes of ribs is not seen in the literature.

We have reported the interfacial instabilities or viscous fingering instabilities in rotating radial Hele-Shaw cell (HSC). The cell is rotated with constant or time-dependent angular velocity about an axis perpendicular to the plane of the flow. Inside the cell, a low viscous fluid displaces a high viscous fluid. Due to this unstable displacement inside the cell fingers like pattern appears at the fluid–fluid interface. It is called viscous fingering (VF). Interfacial instabilities are usually undesirable in engineering applications (dendritic growth decreases the life of rechargeable lithium batteries, VF decreases sweep area due to this reason efficiency of enhanced oil recovery decreases) but it is also beneficial for some practical applications (improving the CO2 mixing in saline aquifers for carbon sequestration, enhancing the mixing efficiency in microfluidics devices). Therefore active control (suppress or promote) of the interfacial instabilities is an important aspect. Many researchers have been done work on active control of interfacial instabilities in radial rotating HSC. A few of them we have taken in this paper. Researchers have been found fluid–fluid interfaces destabilized in radial rotation HSC mainly by centrifugal forces (density differences) and viscosity contrast. The interfacial instability in the radial rotating Hele-Shaw cell depends on rotational velocity (Ὼ), gap between plates (b), wettability of cell, viscosity, density and surface tension. We have reported many research works related to active control of interfacial instability by the above parameters in radial rotating radial HSC.

The hypersonic industry has been developing with the invention of the scramjet engine. The researchers are making persistent attempts to understand the theory behind the complex flows generated due to supersonic combustion. In the current paper, a numerical study has been accomplished using Ansys 14-FLUENT code for studying the characteristics of the flame in a cavity-based supersonic combustor for a Mach number such as 3.0, 3.25, 3.50 with hydrogen is used a fuel. The simulations are carried out by considering SST K-omega turbulent model and compressible Reynolds Averaged Navier Stokes (RANS) equations. The present study is validated with an already available experimental study. The results are in good accord with the results of the experimental study. The results of the simulation are found by varying Mach numbers. The results of the study indicate that there is a movement in the oblique shock wave in the downstream of the hydrogen inlet with the increase in Mach number.

The scramjet engine is categorized in air-breathing vehicles, and this engine utilizes the high-speed forward motion of the vehicle to compress the surrounding air for getting forward thrust. Air-breathing engines complete the cycle by using air from the atmosphere. In the scramjet engines, the atmospheric free stream air enters the combustor at supersonic speed. And the process of mixing and combustion both take place at the same speed. Due to the higher speed of incoming air, the residence time is less inside the combustor. This phenomenon leads to poor mixing of fuel and air. As the scramjet engine does not have any moving part, so there is very less way to improve the performance. One of the optimum ways is fuel injection strategies to enhance combustion performance. To incorporate the behavior of the fuel entrance inside the combustor with the performance of the engine, a detailed literature review has been done in three separate sections by their preferences, i.e., parallel, transverse, and combined fuel injection system. A detailed literature review has been performed to understand and explain the impact of the different fuel injection system at supersonic speed. The parallel fuel injection system at supersonic speed gives higher combustion performance when the additional vortices present. These stream wise vortices can be generated with the help of different shapes of a fuel injector. In the transverse fuel injection system, the total pressure recovery is found less nonetheless stable flame can be achieved by using cavities at the walls. The recirculation zone can easily be created near to this zone. As parallel and transverse fuel injection systems give the best performance among all in their own way however fewer research has been performed in the direction of combined fuel injection strategy at supersonic speed. Flame holding capacity with additional vortices formation can only be achieved by using a combined system.

This article is written with the purpose to gather literature review on sustainable manufacturing. Many frameworks were analyzed and formulated. Various papers on this topic were searched and contents were explored analytically. Their association consists of correlation, differences, overlapping area, and integration of various forms and parts of sustainable manufacturing. Total of 60 papers of identical research were studied and reviewed for the research methodologies, their contributions, and relevant concepts. The article shows the foremost gaps in the field of research for sustainable manufacturing through different aspects. This article provides a quantitative analysis to offer an investigation of various concepts of sustainable manufacturing. In conclusion, here in this article, we emphasize over exclusive analysis of sustainable manufacturing through the recognization of various factors when many literature reviews are there with only the objective of pondering over sustainable manufacturing concepts. One more distinctive quality of this article is that total of 60 research papers have been studied before reviewing. The time frame of 18 years (2001–2018) is considered for this review.

In the present investigation, we explore the morphological evolution of a ferrofluid drop impacting on a solid substrate in the presence of a vertical magnetic field. The morphological evolution of the droplet is quantified by the change in its height, diameter, and contact line velocity. Two types of liquid drop are used in the present investigation viz. a water-based ferrofluid drop and a glycerol-based ferrofluid drop. The glycerol-based ferrofluid droplet acts as a viscoelastic drop. A comparative analysis of the impact dynamics is carried out between two different liquid drops in the presence/absence of a magnetic field. It is shown that the effect of fluid elasticity brings about a controllability on the impact dynamics in the presence of a magnetic field. The experimental investigations revealed that the viscoelastic ferrofluid drop in the absence of a magnetic field encounters a negligible recoiling effect. However, in the presence of a vertical magnetic field, the drop experiences significant recoiling of the contact line. Also, it is shown that the maximum deformation encountered by the drops is directly related to the strength of the applied magnetic field.

In the advancement of computational code, demonstration depicts essential elements. An attempt has been made to develop a finite volume in viscid non-equilibrium flow solver especially the flow of carbon-dioxide to study Martian atmospheric condition. The present study utilizes Venkat Krishnan limiter to provide second-order accuracy. The solver is incorporated by higher-order reacting convective or in viscid fluxes, AUSM scheme. The code is inspected by flowing carbon dioxide over sphere of diameter 25.4 mm and shock stand-off distance is measured at two different velocities, i.e., 4.220 km/s and 2.845 km/s. Similarly, for a ramp at angle 10 and 20 degrees the results obtained in terms of pressure ratio, temperature ratio, and wave angle by the solver are validated with an analytical approach. For all the cases studied, in house-solver exhibit satisfying agreement. Additionally, its capability can be enhanced by incorporating various flux evaluation schemes.