Transactions on Engineering Technologies

The coupling between natural convection and conduction within rectangular enclosure was investigated numerically. Three separate heat sources were flush mounted on a vertical wall and an isoflux condition was applied at the back of heat sources. The governing equations were solved using control volume formulation. A modified Rayleigh number and a substrate/fluid thermal conductivity ratio were used in the range

10

4

−

10

7

$$ {10}^4-{10}^7 $$

and

10

−

10

3

$$ 10-{10}^3 $$

respectively. The investigation was extended to examine high thermal conductivity ratio values. The results illustrated that, when Rayleigh number increased the dimensionless heat flux and local Nusselt number increased and the boundary layers along hot, cold and horizontal walls were reduced significantly. An opposite behaviour for the thermal spreading in the substrate and the dimensionless temperature, were decreased for higher Rayleigh number. Moreover, the thermal spreading in the substrate increased for higher substrate conductivity, which affected the temperature level. However the effect of the substrate is negligible when the thermal conductivity ratio higher than 1,500.

The objective of this paper is to present formulations developed for soil-building interaction analysis, including foundations. The soil is modeled with the boundary element method (BEM) as a layered solid which may be finite for the vertical direction, but is always infinite for radial directions. Infinite boundary elements are employed for the far field simulation, allowing computational cost reduction without compromising the result accuracy. Beams, columns and piles are modeled with the finite element method (FEM) using one dimensional elements. Slabs and rafts are also modeled with the FEM, but with two dimensional elements. The analysis is static and all materials are considered homogeneous, isotropic, elastic and with linear behavior.

Reliability is of increasing importance for electronics systems operating at harsh environments, such as the electronic telecommunication systems used at subsea level. The aim of this research was to investigate the reliability of such electronic systems through a simulated accelerated thermal cycle test. The paper presents a step-by-step process of designing accelerated thermal cycle test using field operating conditions. The Coffin-Mansion equation was used to calculate the accelerated factor for the thermal cycle test. In order to simulate the expected life time of 25 years, the solder assembly samples were subjected to 400 temperature cycles, with every cycle lasting for 40 min. Reliability was determined by measuring shear strengths of solder joints of different electronic components at set intervals. Although some of the components showed an initial decrease in shear strength, it was generally concluded that the electronic assemblies are able to maintain their shear strength for up to 25 years. The fracture surfaces of the solder joints, after shear testing, were also analyzed for brittle and ductile fractures, with the use of scanning electron microscopy (SEM).

This paper is devoted to the mathematical theory of the existence and uniqueness of the three dimensional Navier-Stokes solution for convergent-divergent flows. Using rotor operator and a well-known formula of vector analysis was obtained the nonlinear Volterra-Fredholm integral equation in a matrix form containing only three components of velocity vector which was solved by using the successive approximation method. Considering the pressure gradient as a potential field was determined the balance equation for defining the distribution pressure. Due to the obtained balance equation for the scalar pressure distribution were defined significant properties of the transient convergent-divergent flows with which provided a description of the constitutive relationships between three physical quantities: the velocity vector, the external and internal forces, the pressure distribution. According to the defined estimations of the velocity vector were proved the uniqueness theorems for the convergent-divergent Navier-Stokes problem in the general case.

The thermomechanics of growing bodies studies the distributions of mechanical and thermal fields in quasistatic and dynamic processes that occur in the bodies whose composition varies in the process of deformation and heating. These types of accretion are realized in various technological processes such as laser surfacing, gas-dynamic deposition, and vapor phase deposition. Mathematical modeling of the deformations and temperature fields arising in these processes allows one to optimize the technological processes and is a topical problem of mechanics of deformable rigid body. The present work is concerned with the initial boundary-valued problem for the thermoelastic growing block. Full coupling of mechanical and thermal fields as well as relaxing of the heat flux are taken into account. A closed form solution for a body under “smoothly rigid” heat-insulated conditions for the stationary faces and the load-free conditions on the growing face is obtained. The temperature field on the growing face is analyzed numerically for various accretion scenarios.

The problem with crude oil depletion has arisen in the last years. There has been intensive research to find out alternative to fossil fuels. The main group is biofuels, produced from crops and wastes. Alcohols are an important category of bio-fuels. Ethanol is a good candidate to be an alternative fuel since it is a liquid and has several physical and chemical properties similar to those of gasoline fuels. That is why this study is aimed to develop the 1-D combustion model of four-stroke spark ignited engine for predicting the effect of various fuel types on engine performances and fuel consumption on various engine operating conditions. AVL Boost was used as a computational fluid dynamics simulation tool to analyze the performance and emissions characteristics for different blends of ethanol and gasoline (by volume).

Mathematical modeling of additive manufacturing technologies is aimed at improving the performance of device, machine, and mechanism parts. These technologies include stereolithography, electrolytic deposition, thermal and laser-based 3D printing, 3D-IC fabrication technologies, etc. They are booming nowadays, because they can provide rapid low-cost high-accuracy production of 3D items of arbitrarily complex shape (in theory, from any material). However, deformation and strength problems for products manufactured with these technologies yet remain to be solved. The fundamentally new mathematical models considered in the paper describe the evolution of the end product stress-strain state in additive manufacturing and are of general interest for modern technologies in engineering, medicine, electronics industry, aerospace industry, and other fields.

In this chapter it is examined the use of finite elements in predicting the cutting forces of machined parts of stainless steel AISI 316 L through turning. The process used the high speed machining technique, which is continuously improved and it has be found application in more and more manufacturing processes like aerospace industry, in die and mold companies and in the last years also in bioengineering in manufacturing hip joint implants. The cutting forces, which were measured through experimental process, were compared with predicted ones from the finite element modulation, and it was exported that they can be predicted with good precision when machining with the FEM model.

The paper describes a mechanical slope developed to investigate rainfall-induced shallow landslides in loose coarse-grained soils, which can evolve into high-speed flowslides with propagation capabilities even in areas with very low gradients, putting people’s lives and property at risk. The mechanical slope is the main component of an experimental plant built at the University of Naples. It consists of two inclinable parts: the upper one where the soil sample is deposited and the flowslide is generated, and the lower part that allows flowslide behaviour to be observed. The monitoring system implemented consist of load cells which measure the sample weight changes, tensiometers and Time Domain Reflectometry (TDR), which measure, respectively, soil suction and water content at different depths, Particle Image Velocimetry (PIV) and a Laser scanner techniques which provide the sample surface movements.

Grade 5 titanium (Ti6Al4V) is considered as the workhorse titanium alloy. It is widely termed an aerospace alloy and is a relatively new engineering material. One of the major challenges in the use of this aerospace material is its machinability. Its high strength which is maintained at elevated temperatures, low thermal conductivity, low elastic modulus and high reactivity with oxygen is a perfect recipe for machining challenges. This leads to high tool wear and long production times. Such challenges can be overcome by electrical discharge machining (EDM). Given that titanium is usually applied to mission critical components (gears, shafts, wing sections etc.), it is important to understand the possible effect of wire EDM (WEDM) on their structural performance. The purpose of this chapter is to present critical issues related to the effect of wire EDM on the fracture toughness of this aerospace material. EDM and WEDM processes are discussed. Their effects on the structural integrity of Ti6Al4V are then demonstrated through fracture toughness measurements. Four specimens were produced using wire EDM. This includes the pre-crack which is usually introduced by fatigue cycling. Obtained results indicate a slight decrease in fracture toughness compared to that reported in literature. It was also concluded that wire EDM technique can be used as an alternative to fatigue pre-cracking in fracture toughness testing of Ti6Al4V.

To suggest cost-effective designs of steel beams with circular opening under Vierendeel failure, computational results of the available methods such as SCI P100, SCI P355, Chung et al.’s formula and Panedpojaman and Rongram (PPM)’s formula for evaluating the load carrying capacity based on Vierendeel failure is investigated. The failure load are investigated, in terms of the normalized moment-shear interactions for the steel beams and the maximum shear loads for the cellular beams, and compared with finite element analysis. A total of 114 non-linear finite element models of steel beams with singular openings and cellular beams are used in this study that covers various beam section sizes and opening parameters. Comparing with the FE results, the available methods conservatively provide the failure loads for steel beams with a single opening and cellular beams. It is also found that sizes of the steel sections less affect the FE interaction curve’s shape. The interactions are slightly degraded for the large opening ratio. Comparing with the FE analysis, SCI P100, SCI P355, Chung et al.’s formula and PPM’s formula are conservative to evaluate the interaction up to 40%, 25%, 20% and 10% respectively, under the high shear ratios. However, the methods provide the less conservative interaction and the Vierendeel failure load under the high moment ratios.

The mechanics of the knee was analyzed in the sagittal plane to study effects on patellar tendon force as influenced by placement of external flexing loads on the tibia and by translation of the tibial bone 7 mm anterior to the femoral bone during the flexion range 0–120°. Anatomical parameters and measurements for orientations and moment arms of the patellar tendon during the flexion range were estimated from experiments on cadaver knees available in the literature.

The analysis suggests that the force in the patellar tendon varies directly with the distance of external flexing load placed distal to the tibial surface. This effect is uniform throughout the joint flexion range. Further, 7 mm anterior translation of the tibia relative to the femur resulted in significantly reduced anterior component of net shear force for all flexion positions and all placements of loads distal to the joint line. This has relevance to ACL-deficient knees where large tibial translations may be necessary to compensate for the deficiency (ACL is anterior cruciate ligament).

Two critical factors that may require special attention to protect the ACL during rehabilitation exercises are the flexion angle and the position of flexing load below the tibial surface.

Fluid-structure interactions for a single tree and a pair of trees with varying spacing subjected to

gentle breeze

and

storm

wind conditions were evaluated using Computational Fluid Dynamics (CFD). The generated velocity and pressure fields are then analysed using Finite Element Analysis (FEA) to determine the likelihood of tree damage due to the aerodynamic loads induced by the two wind conditions. It is observed that the pressure difference between the windward and leeward sides of the trees are much larger during the

storm

condition resulting in greater mechanical stresses and deformation magnitudes experienced by the tree trunks. Increasing the spacing between neighbouring trees resulted in larger aerodynamic loads on the sheltered trees downstream.

A study of quench agitation by immersion speed variation was carried out on a C30 carbon steel material and examination of resulting mechanical properties. Quenching was carried out in a special extended height bath under conditions of constant bath temperature and a variable immersion speed. Material thermal history data was taken during the quench process and mechanical properties comprising of hardness and tensile strength of material were examined thereafter. Immersion speed variation was effected by a variable weight-force application acting on the quenched C30 specimen falling freely through an extended height quench bath. At immersion speeds of 0.106, 0.697, 0.853, 1.065 and 1.139 m/s; the yield strength of the material are 310.40, 496.12, 500.56, 565.40 and 579.92 MN/m

2

respectively while at a typical location of radius 15 mm on specimen mid-height the corresponding hardness values at the respective immersion speeds are 275, 293.40, 454.60, 408 and 594 VHN. There is an enhancement of mechanical strength with immersion speed increase.

In this study, air flow through a three-dimensional room fitted with a two-sided windcatcher is observed numerically, using a commercial computational fluid dynamics (CFD) software package. A LES (Large Eddy Simulation) method is used and the results are compared with those obtained previously by using a RANS (Reynolds Averaged Navier-Stokes) technique. Since LES is generally considered as more accurate but requiring more computational efforts than RANS, the results obtained in this work would verify the RANS results which have covered many more cases in addition to the one considered in this work. The LES and RANS results for the windcatcher configuration considered in this work are in good agreement. Specifically, it is confirmed that the two-canal centred position windcatcher with the bottom length of 10 cm provides full circulation for most part of the room and a large region of stable velocity in the acceptable range of indoor air speed for human comfort.

The vertical axis wind turbine aerodynamics are highly complex and unsteady. Inherent in the operation of VAWTs is the presence of the dynamic stall phenomenon that has a major influence in the overall performance of the rotor. The acquisition of a reliable experimental flow field data set presents a means to increase the level of understanding of VAWT performance and flow physics through visualisations. The method developed in this study includes the setup of the PIV system in the wind tunnel, surface treatment of the VAWT blades, verification of test settings, and image processing and data analysis. The measurement of the flow fields around a VAWT blade at tip speed ratios of λ = 2.5 and 4 were carried out and the results show significant differences in the stalling characteristics between different λ with increased occurrence of deep and prolonged separation of flow from the blade surface at lower λ. In both cases, however, dynamic stall is observed. The data acquired is an invaluable reference for VAWT flow physics as well as validation of numerical models such as CFD.

The finite deformations of the growing cylinder of incompressible elastic material are under consideration. We assume that the deformations are axisymmetric and do not change along the axis of cylinder. The discrete and continuous types of growing are studied. The analytical solutions of the corresponding boundary-value problems are derived. The results of numerical simulation of both discrete and continuous growth are given.

The aim of this research is to design and fabricate pilot multi-tube boiler using a diesel fired burner (C

13

H

25

)

9

to generate 80 kg of steam hour. The boiler tank is made of pure mild steel. Mild steel is used to fabricate the fire tubes and other parts such as the furnace, smokestack and return chamber that make up the boiler. The heating surface area was increased for sake of efficiency and fast steam generation by reversing the direction of the gas through a second and third parallel tube (three pass). The boiler (which is fired by a diesel burner) generates dry saturated steam at a pressure of 1.5 bars and temperature of 111.4 °C. It can be used for domestic and industrial purposes.

In the present paper, CFD simulations using ANSYS-Fluent 14.5 were accomplished to study the effect of bed or sand inventory and effect of scale-up of riser on heat transfer characteristics like temperature and heat transfer coefficient. To accomplish the scale-up study, 3D CFD simulations were performed on the Circulating Fluidized Bed (CFB) risers of cross section 0.15 × 0.15 m, 0.30 × 0.30 m, and each of height 2.85 m. CFD simulations to predict heat transfer characteristics were accomplished under same operating conditions on heated portion (heater) of both risers. The walls of heater were maintained at the constant heat flux q

″ 

= 1,000 (W/m

2

). Modeling and meshing were done using ProE and ANSYS ICEM CFD software, respectively. RNG k-ε model was used for turbulence modeling. Eulerian model with Gidaspow phase interaction scheme was used to simulate the two phase flow (air + sand mixture flow). Computational (CFD simulation) data was compared with experimental data for the validation purpose. After validation, further simulations were conducted on riser of cross section 0.30 × 0.30 m. Based on scale-up study, empirical correlation has been developed to predict the heat transfer coefficient.

This research has indicated that, by using a computer model, a numerical method can be effective in predicting the tool tip temperature. This allows the effects of changes made to the machining parameters to be simulated. Temperatures through the tool tip can therefore be reduced by using the optimum cooling method for particular machining parameters.

In make-to-order system orders are scheduled for production based on the due date agreed with customer and the strategy of company. Production planning of such system includes scheduling of orders to the production periods and allocation of workers at different work centers. Complexity in the system arises when the operation to perform next and its processing time is skilled dependent where a higher qualified worker type can substitute a lower qualified one, but not vice-versa. Under such working environment, efficient scheduling of orders and allocation of workers at different work center play major role to improve system performance. This paper develops a mathematical model for make-to-order flow shop system under hierarchical workforce environment. The model helps identify optimum schedule of orders and allocation of workers with an objective of minimizing the weighted average earliness and tardiness. A heuristic method is also proposed to overcome the complexity of mathematical model and solve the problem efficiently. Numerical analysis indicates that proposed heuristic is capable of finding optimal or near optimal solution in a considerably reduced amount of computational timing.

The purpose of this research is the development of a supply chain framework in order to provide the process reference model based on the relationship between entities. This research chooses multiple cases of oil palm refinery in Malaysian because there is a barrier in implementing supply chain strategy in the form of inadequate measurement performance system. The methodology developed in this research comprised three phases involving business process reengineering, supply chain relationship model and performance indicator. There are 35 refineries in the peninsular Malaysia. However, measurement of supply chain performance will be selected in 6 oil palm refineries. The findings show that the conceptual framework can provide an instrument to analyze supply chain performance and evaluate the existing supply chain strategy.

This paper reports the development of the mathematical modeling of an abrasive electrochemical grinding (AECG) process. In AECG a metal-bonded grinding wheel is used instead of a graphite or metal wheel-electrode used in electrochemical grinding (ECG). Therefore, the mechanical abrasion is combined with the electrochemical dissolution. Significant improvements in material removal rates have been observed with AECG of advanced materials, such as superalloys, sintered carbides and metal matrix composites. The interaction of the abrasion and electrochemical dissolution in AECG is analyzed on the basis of computer simulation of the material removal process. The effects of main machining parameters such as feed rate, voltage and grit protrusion is studied.

The effects of in-process cryogenic LN cooling on the resulting grain size of the friction stir processing (FSP) of twin roll cast (TRC) magnesium alloy AZ31B. Sheets (3 mm-thick) of TRC AZ31B were friction stir processed using a wide range of processing parameters (mostly tool feed and spindle speed). The tool rotational speed was varied between 600 RPM and 2,000 RPM while the tool feed rate varied between 75 mm/min and 900 mm/min. Thrust force and torque values were experimentally measured using a 4-component dynamometer. Temperature measurements were monitored during the different tests using Infrared sensors and thermocouples. The microstructure of processed samples was observed using optical microscopy. It was found that thrust force and torque values of the pre-cooled samples were 5% higher than those of the room temperature samples due to the material hardening induced by the cooling effect. Finer and more homogenous microstructure was observed for the pre-cooled samples when compared with samples processed at room temperature. The average grain size of pre-cooled samples was predicted using a relation -previously introduced by the authors- that relate grain size and the Zener-Hollomon parameter for TRC AZ31B. This equation was found to correctly predict grain diameter for in-line cooled FSP AZ31B samples at temperatures lower than room temperature.

In industry, the evolution of productivity and quality of mechanical manufacture of complex shape parts (mold, automobile, form…) is marked by the development of several machining simulation techniques for modeling and predicting the manufacturing process to represent the most realistic cut phenomenon. There exist several machining simulation techniques and touch various levels. Thus, this chapter summarizes the literature review and presents the techniques in a simplified scheme for the rapid exploration in this area, and in order to direct the reader to select an appropriate approach linked to a geometric or physical problem at a given scales in Part-Tool-Machine system. Particular attention is given to geometric simulation methods of the macroscopic scale; completed by brief comparison between models of workpiece representation for material removal process (Dexel, Voxel, Triple-Dexel).

During the last decade biodiesel production facilities have had a fast growth all over the world. Production levels and installed capacity have increased continuously to respond the demands of renewable oils. This growth has been accompanied by increasing accident rates. This fact raises the necessity of understand accidental causes in order to eliminate or diminish them. The present study applies the Reason’ Swiss Cheese model of Human Error to a series of accidents that have taken place at biodiesel facilities in the period 2003 to January 2014. It allows identifying the unsafe acts and latent conditions that have conducted to accidents, and implementing tools to manage them.

Multiple response optimization problems have many optimal solutions that impact differently on process or product. Some of these solutions lead to operation conditions more hazardous, more costly or more difficult to implement and control. Therefore, it is useful for the decision-maker to use methods capable of capturing solutions evenly distributed along the Pareto frontier. Three examples were used to evaluate the ability of three methods built on different approaches for depicting the Pareto frontier. Limitations of a desirability-based method are illustrated whereas the consistent performance of an easy-to-use global criterion gives confidence to use it in real-life problems developed under the Response Surface Methodology framework, as alternative to the sophisticated physical programming method.

This paper, by experimental and investigation, examines the effects of dry and flood cutting conditions by comparing the rate of tool wear during metal turning and the produced surface roughness to determine if dry cutting can be a cost effective solution. For efficient manufacturing, the surface roughness of the turned parts should be dependent on their intended application, factors such as environment of operation or further manufacturing processes will determine this level of surface roughness required, as the performance and mechanical properties of the material can be affected. EN8 steel has been selected as the work material for its popularity and low hardness. The results show both wet and dry conditions have their benefits in relation to the intended application of the part, but mostly dry turning produces competitive surface roughness when finished by turning when compared to wet, and acceptable levels of tool wear while rough cutting. It would be recommended that in most circumstance for rough cutting, dry conditions should be employed with the knowledge of slight increased tool wear and possibly shorter life but with reduced manufacturing costs and environmental hazards.

In the first stage of a manufacturing process a large number of variables might be available. Then, a smaller number of measurements should be selected for process monitoring. At this point in time, variable selection methods for process monitoring have focused mainly on explained variance performance criteria. However, explained variance efficiency is a minimal notion of optimality and it does not necessarily result in an economically desirable selected subset, as it makes no statement about the measurement cost or other engineering criteria. Without measuring cost many decisions will be impossible to make. In this article, we propose two new methods to select a reduced number of relevant variables for multivariate statistical process control that makes use of engineering, cost and variability evaluation criteria. In the first method we assume that a two-class system is used to classify the variables as primary and secondary based on different criteria. Then a double reduction of dimensionality is applied to select relevant primary variables that represent well the whole set of variables. In the second methodology a cost-utility analysis is used to compare different variable subsets that may be used for process monitoring. The objective of carrying out a cost–utility analysis is to compare one use of resources with other possible uses. To do this, to any process monitoring procedure is assigned a score calculated as ratio of the cost at which it might be obtained to explained variance that it might provide. The subset of relevant variables is selected in a manner that retains, to some extent, the structure and information carried by the full set of original variables.

Wireless networks have been widely and intensively used on a global scale. In accordance with such a use, the limitation of the total throughput of an access point (AP) for the network has become a problem. This problem is especially serious when the AP is accessed by a lot of wireless terminals because the total throughput of the AP becomes much smaller than expected due to the collision of accesses by the terminals. Although a lot of researches have been conducted to solve this problem, their results are far from satisfactory since the total throughputs achieved by the researches are rather limited. Thus, the purpose of this paper is to propose a novel approach to achieve high total throughput regardless of the number of terminals accessing an AP. This paper clarifies the main principles of the proposed approach with its detailed algorithm for the access control. Furthermore, this paper demonstrates that the throughput achieved by the proposed approach is much higher than that of the current IEEE standards and that the throughput by the proposed approach is close to its theoretical upper limit through some computer simulation results.

This work compares the performance of indoor positioning systems suitable for low power wireless sensor networks. The research goal is to study positioning techniques that are compatible with real-time positioning in wireless sensor networks, having low-power and low complexity as requirements. Map matching, approximate positioning (weighted centroid) and exact positioning algorithms (least squares) were tested and compared in a small predefined indoor environment. We found that, for our test scenario, weighted centroid algorithms provide better results than map matching. Least squares proved to be completely unreliable when using distances obtained by the one-slope propagation model. Major improvements in the positioning error were found when body influence was removed from the test scenario. The results show that the positioning error can be improved if the body effect in received signal strength is accounted for in the algorithms.

Wireless sensor networks are becoming significantly vital to many applications, and they were initially used by the military for surveillance purposes. One of the biggest concerns of WSNs is that they are defenseless to security threats. Due to the fact that these networks are susceptible to hackers; it is possible for one to enter and render a network. However, WSN presents many challenges. These networks are prone to malicious users attack, because any device within the frequency range can get access to the WSN. There is a need for security mechanisms aware of the sensor challenges (low energy, computational resources, memory, etc.). Thus, this work aims to simulate a secure routing protocol for WSN by using trusted frame works called SAODV. The Trust Scheme evaluates the behavior of all nodes by establishing a trust value for each node in the network that represents the trustworthiness of each one thereby identifies and eliminates the malicious nodes. It also observes node’s mobility, number of neighbors each node has, number of packets generated and forwarded by the neighboring nodes, and the past activity of the node.

Innovation in social networking media has revolutionized the world in twenty-first Century. Social networking media presents potentially opportunities for new forms of communication and commerce between marketers and consumers. Objective of the study is to analyze the effective communication strategy through social networking media. Survey was conducted randomly among Facebook user community, by sending questionnaire through online to collect the individual opinion from the respondents. The total population is social networking user community, but to collect the effective data the sampling is constrained to the target population like young adults, graduates within the age of 18 years to 55 years. The sampling size is 400. The paper presents research results and internet marketing activities that have contributed to building a relationship with the brand. It is necessary to study the effectiveness of brand communication strategy followed in social networking media which are mainly accessed by Slovenian users. This study would help the advertisers to understand the effective communication strategy to communicate their brand among the users. In recent trend of marketing in social networking sites, various brand communications are widely used to attract targeted leads. So, this study would help to know the effectiveness of communication and strategy done through social networking media which make the target audience to participate in this kind of advertising.

An active integrated Radio Frequency Identification (RFID) system that operates in 2.45 GHz ISM band frequency is developed to support indoor and outdoor real-time location monitoring by utilizing Global Positioning System (GPS) in Wireless Sensor Network (WSN) and Global System for Mobile (GSM) communication platform. The proposed active RFID system is based on an automated switching mechanism between indoor and outdoor location and the capabilities of the system is extended by providing a contactless communication between the tagged items or persons and the monitoring station. There are two types of communication protocol; Reader Talk First (RTF) and Tag Talk First (TTF) involved in the proposed RFID system. The effectiveness of the proposed RFID system is evaluated based on the communication protocols implemented and the capability of the proposed RFID reader to read multiple tags is tested by analyzing the tag collection process in the RFID system. From the results, it is shown that the system with TTF protocol is better than the RTF protocol in terms of data collision and average time delay while performing transmission and reception processes.

Today, almost every individual possesses at least one internet-connected device. According to Cisco, there were over 12.5 billion devices in 2010 alone. It has been predicted that 25 billion devices will be connected by 2015, and 50 billion devices by 2020; all contributing towards the Internet of Things (IoT). This rapid increase exposes the obvious need for enhancements in various underlying technologies. IPv6 for example, has been developed to provide 340 undecillion IP addresses, and 3GPP LTE and its further enhancements provides impressive high bitrates cost-efficiently. That been said, there is still a limit on the amount of data that can go through a frequency channel. Therefore, the surge in demand for data by the billions of devices emphasizes the need to re-visit spectrum planning. Beginning with a review on the success of unlicensed spectrum operations, this work looks into the potentials of complementing the licensed frequency bands with unlicensed by tapping into the advantages of millimeter wave access technology.

Recently a lot of research effort has been focused on Wireless Sensor Networks (WSNs) due to its various applications. Over the last few years, several techniques have been proposed for investigating the power consumption which represents one of the most challenges and main concerns in designing WSNs. Power consumption of nodes in WSNs has a great effect on the lifetime of network nodes which are difficult to replace or recharge their batteries. In this context, this paper represents a receiver approach for alleviating power consumption of WSNs. Unlike other power consumption techniques, instead of decoding every received signal at the receiver which consume too much power our approach studies the histograms of sensors’ transmitted signals to detect collisions, so the receiver can determine when the transmitted signals can be decoded without wasting precious power decoding transmitted signals suffering from collisions. We also present a complexity and power-saving comparison between our novel approach and a conventional full-decoding algorithm in order to demonstrate the significant power and complexity saving advantage of our approach.

One of the difficult challenges in Cognitive Radio Ad Hoc Networks (CRAHNs) is the throughput maximization in an environment with uncertain availability of spectrum resources and spatial diversity. Opportunistic spectrum utilization can alleviate the degradation in throughput by employing dynamic routing algorithm and accomplishing Virtual Path Routing (VPR). The VPR aims at finding the most reliable path for multi-hop communication between Secondary Users (SUs) in the presence of Primary Users (PUs) and other interfering SUs. By joint routing and dynamic spectrum access with interference avoidance, VPR selects the path, which ensures optimal link throughput with minimum interference. In this chapter, two utility functions are proposed for cognitive networks routing. The first utility function incorporates probabilistic Signal-to-Interference Ratio (SIR), PU influence and channel switching time delay. The second proposed utility is based on minimizing power consumption to improve battery lifetime. The VPR performance is compared with other well known works in terms of throughput, Bit Error Rate (BER) and Packet Arrival Delay (PAD). The results suggest VPR provides better end-to-end throughput, BER and PAD by avoiding zones of PU presence and mitigating interference effects of neighboring SUs. It is observed that applying a power control scheme such as water-filling, the VPR shows improved throughput. The BER for VPR with water-filling is also reduced compared to the previously suggested scheme such as Gymkhana alongwith the efficient power consumption.

Simulation of VoIP (Voice over Internet Protocol) traffic through UMTS (Universal Mobile Telecommunication System) and WiFi [Wireless Fidelity] (IEEE 802.11x) in isolation and combined are analysed for the overall Quality of Service (QoS) performance. The average jitter of the VoIP traffic transiting the WiFi-UMTS network has been found to be lower than that of either solely through the WiFi and the UMTS networks. It is normally expected to be higher than traversing through the WiFi network only. Both the subjective MOS (Mean Opinion Score) and the objective packet end-to-end delay were also found to be much lower than expected through the heterogeneous WiFi-UMTS network.

Wireless communications using microwaves are increasingly important, such as Wi-Fi. Performance is a most fundamental issue, leading to more reliable and efficient communications. Security is equally very important. Laboratory measurements were performed on several performance aspects of Wi-Fi (IEEE 802.11a, b, g) WEP point-to-multipoint links. Our study contributes to performance evaluation of this technology, using available equipments (DAP-1522 access points from D-Link and WPC600N adapters from Linksys). New detailed results are presented and discussed, namely at OSI levels 4 and 7, from TCP, UDP and FTP experiments: TCP throughput, jitter, percentage datagram loss and FTP transfer rate. Comparisons are made to corresponding results obtained for WEP point-to-point and Open point-to-multipoint links. Conclusions are drawn about the comparative performance of the links.

This chapter discusses the structure of

deterministic

Ethernet which helps to improve the security and accessibility of services in a time critical communication system. Frame switching is the method of connecting frames to their destination. A disorganised frame switching network increases the fluctuation of application response times and creates weakness in a sensitive network. Dynamic frame traffic oscillation allows the frame workload to be more organised and manageable for networking by isolating external influences that disrupt network service. This concept, which we term

Critical Networking,

organises networks and reduces network resource wastage, such as overheads, thereby reducing application network frame delay by carefully planning the type of frame transmission and the available network resource. The frame traffic is handled by a network traffic oscillator (NTO), which creates deterministic time response in frame transmission. Both concepts when combined remove the need to assign arbitrary priority numbers in frames, and overheads for consecutive application transmissions and hides sensitive overhead information within every frame. The concept is illustrated using a simulation of real-time traffic in an airfield scenario.

In this work, we present an adversary model that incorporates side channel attacks in the Indistinguishability Experiment for Adaptive Chosen Ciphertext Attack (CCA2). We propose security assumptions and an attack model for a secure SSW-ARQ protocol with an integration of TFTP protocol. We also present the security reduction of SSW-ARQ protocol from Cramer-Shoup encryption scheme, timing and power attacks as side channel security for the SSW-ARQ protocol. We suggest using a lightweight symmetric encryption for data encryption and asymmetric encryption for key exchange protocols in the TFTP. The target implementation of secure TFTP is for embedded devices such as Wi-Fi Access Points (AP) and remote Base Stations (BS). In this paper we present the security proofs based on an attack model (IND-CCA2) for securing TFTP protocol. We have also introduce a novel adversary model in IND-CCA2-(TA, PA, TPA) and it is considered a practical model because the model incorporates the

timing attack

and

power attack.

The security of message transmission is usually a challenge for its participants. Many available programs that work with audio data claim to enable secured communication, but usually do not show the details of the methods used for data encryption. For end users to be confident, it is essential to be aware of the methods and techniques used for data encryption and decryption. Elliptic curve cryptography, an approach to public key cryptography, is now commonly used in cryptosystems. Hence, in this paper we present a method for using elliptic curve cryptography in order to secure audio data communications. Furthermore, we present a tool that implements this method for encrypting an audio file, transmitting it through the network and decrypting the file at the other end.

In this chapter, we present a series of secret keys distribution in a key exchange protocol that incorporates protection against side channel attacks using Indistinguishability Experiment (modified) for Adaptive Chosen Ciphertext Attack (CCA2). We also present a security analysis and a new attack model for a secure Chain Key Exchange Protocol with an integration of TFTP protocol in the UBOOT firmware. To enable RasberberryPi

“system on chip”

(SoC) to perform cryptographic computation, we modified the GNU GMP Bignum library to support a simple primitive cryptographic computation in the UBOOT firmware. We suggest using our key exchange protocol for a secure key distribution in the UBOOT’s TFTP protocol. Latter, the TFTP protocol can use the secure key which has been distributed by our key exchange protocol to encrypt the TFTP’s data using another symmetric encryption scheme such as AES256. Lastly, we introduce a variance of adversary model in IND-CCA2-(TA, PA, TPA) which may be considered as a more realistic and practical model because it incorporates

timing attack

and

power attack.

Forensics is undertaken to find out exactly what happened on a computing system and who or what was responsible for it. This is done by a structured investigation while maintaining a documented chain of evidence. Cloud computing is emerging as an attractive, cost effective computing paradigm. The early offerings of cloud capabilities have not provided security, monitoring or attribution that would allow an effective forensics investigation. The high assurance requirement presents many challenges to normal computing and some rather precise requirements that have developed from high assurance issues for web service applications and forensics applications of cloud systems. The challenges of high assurance and the maintenance of a documented chain of evidence associated with cloud computing are primarily in four areas. The first is virtualization and the loss of attribution that accompanies a highly virtualized environment. The second is the loss of ability to perform end-to-end communications. The third is the extent to which encryption is needed and the need for a comprehensive key management process for public key infrastructure, as well as session and other cryptologic keys. The fourth is in the availability of monitoring and logging for attribution, compliance and data forensics. Our view of high assurance and the issues associated with web services is shaped by our work with DoD and the Air Force, but applies to a broader range of applications.

In this paper, we have presented some results on undergraduate student retention using signal processing techniques for classification of the student data. The experiments revealed that the main factor that influences student retention in the Historically Black Colleges and Universities (HBCU) is the cumulative grade point average (GPA). The linear smoothing of the data helped remove the noise spikes in data thereby improving the retention results. The data is decomposed into Haar coefficients that helped accurate classification. The results showed that the HBCU undergraduate student retention corresponds to an average GPA of 2.8597 and the difference of −0.023307. Using this approach we obtained more accurate retention results on training data.

We propose in this paper an original method to correct the geometric distortions of a radar image. The comparison of satellite data, reveals specific problems. Data can be noisy, but especially the geometry of their acquisition requires corrections for comparaisons between them. In this paper we show how highly deformed radar images can be geometrically corrected and compared to map data coming from digital terrain models and also with data coming from SPOT satellite. Radar images used, are from the sensor airborne radar Varan, which is used for data acquisition campaign in the South-East of France. Applications include both structural geology, land cover or study of coastline. We propose a solution to rectify radar image in the geometry of a numerical terrain model. The method adopted here, is to produce a synthesis radar image by encoding all flight parameters of aircraft or satellite from a digital terrain model; radar image can then be compared to the synthetic image because points of landmarks can be clearly identified. Finally, we obtain a correspondence between the points of real radar image distorted, and those in the land or map.

The automatic analysis of traffic scene is interesting subject in the context of traffic planning and monitoring. The main objective of this research is to construct an advanced traffic control system according to the changes of road traffic circumstances. The road traffic changes are specified through analyzing the road’s image and identify the traffic load. Two approaches are suggested to specify traffic load. The first approach is measuring the length of car-queues on road based on edge detection using Sobel operator then estimate number of vehicles. The second approach is counting-vehicles on the road based on region growing segmentation algorithm. An equation to specify the estimated time is suggested to determine the time for green-light. The two developed techniques are compared from two points of views: estimate time for green-light period, and the estimated number of vehicles on the road. The impact of density of vehicles on road (low/high) is taken in consideration in comparison process. As a result, it was found that car-queue technique suits high density road, while counting-vehicles technique suits both cases (high and low density) and shows better performance, which is comparable to actual traffic results.

Image processing employing software routines are time consuming in compared to their counterfeits of hardware strategies. Cellular automata appear as abstract models of systems in image manipulation due to their local nature, inherently parallel and computationally simple implementation. This paper addresses a hardware framework based on two dimensional cellular automata, for manipulating images in certain specific positions and orientations. The proposed architecture can be easily implemented using VLSI technology.

This research is aiming to investigate the mechanical behaviour of the temporomandibular joint (TMJ), in response to cyclical loading caused through actions of speech and mastication. A set of in-vitro experimental tests has been performed in three different groups on a fresh sheep jaw bone to examine the hypothesis of the study. No failure was monitored during the cyclical test. The study was concluded that the amount of loading is effective on the displacement of the TMJ.

The paper compares the performance of two classical machine learning techniques when features selection is used to improve Influenza-A host classification. The impact of using the most informative positions on both the classifier efficiency and performance of decision trees (DTs) and neural networks (NNs) was measured. The experiments were conducted on cDNA sequences belonging to all the viral segments of the subtype H1 to ensure authenticity of results. Sequences belonging to each viral segment were further divided into viruses infecting human and non-human hosts prior to classification analysis. The performance measures, accuracy, sensitivity, specificity, precision, and time, were used. Extracting the best hundred informative positions with the information gain (

IG)

algorithm increased classification efficiency for both classifiers by more than 80 % for all viral segments. The change in performance was insignificant. The overall results of statistical significant tests showed that NNs classified viral hosts more accurately than DTs for subtype H1. The tests also showed that the DTs are significantly faster than NNs in classifying Influenza hosts despite the slight decrease in performance.

The optimization of biodiesel production from a Typical Nigerian cottonseed oil using sodium hydroxide as catalyst is presented. 2

3

factorial design was employed to study the combined effect of temperature (40–60 °C), mole ratio of methanol to oil (6:1–8:1) and catalyst concentration (0.5–1.0 wt%). The optimum yield of 96.23 wt% was obtained at 0.5% w/v potassium hydroxide at a temperature of 40 °C and Molar ratio of 6:1 for 90 min. A Model equation that shows the relationship between biodiesel yield and process variables was developed using a statistical tool. Statistical Analysis of variance (ANOVA) of the data shows that molar ratio has the most pronounced positive effect on the biodiesel yield. The methyl ester was characterized and all the properties were consistent with the ASTM standard.