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## Über dieses Buch

This proceedings book features volumes gathered selected contributions from the International Conference on Engineering Research and Applications (ICERA 2020) organized at Thai Nguyen University of Technology on December 1–2, 2020. The conference focused on the original researches in a broad range of areas, such as Mechanical Engineering, Materials and Mechanics of Materials, Mechatronics and Micromechatronics, Automotive Engineering, Electrical and Electronics Engineering, and Information and Communication Technology. Therefore, the book provides the research community with authoritative reports on developments in the most exciting areas in these fields.

## Inhaltsverzeichnis

### Hardware Acceleration of Modern Data Management

Over the past thirty years, database management systems have been established as one of the most successful software concepts. In todays business environment they constitute the centerpiece of almost all critical IT systems. The reasons for this success are manyfold. On the one hand, such systems provide abstractions hiding the details of underlying hardware or operating systems layers. On the other hand, database management systems are ACID compliant, which enables them to represent an accurate picture of a real world scenario, and ensures correctness of the managed data.However, the currently used database concepts and systems are not well prepared to support emerging application domains such as eSciences, Industry 4.0, Internet of Things or Digital Humanities. Furthermore, volume, variety, veracity as well as velocity of data caused by ubiquitous sensors have to be mastered by massive scalability and online processing by providing traditional qualities of database systems like consistency, isolation and descriptive query languages. At the same time, current and future hardware trends provide new opportunities such as many-core CPUs, co-processors like GPU and FPGA, novel storage technologies like NVRAM and SSD as well as high-speed networks provide new opportunities.In this talk we present our research results for the use of modern hardware architectures for data management. We discuss the design of data structures for persistent memory and the use of accelerators like GPU and FPGA for database operations.

Kai-Uwe Sattler

### Electric Vehicle Development and Low-Carbon Transport in Vietnam

Vietnam’s social and economic development achievements are remarkable. However a steep rise in income and economic growth has led to rapid motorization and high energy demand. The transport sector is a major consumer of energy in Vietnam and thus it is one of the key sectors which produces most emissions including green house gas (GHG). As a result, according the emissions per GDP, Vietnam is ranked the 13th most carbon intensive economy in the world, and 4th among the low- and middle- income countries in East Asia. GHG emissions from the transport sector are expected to triple by 2030, to nearly 90 million tons carbon dioxide equivalent (CO2e).In road transport sector, there are about 40 million vehicles, including about 35 million motorbikes, over around 96 million population. Almost all of road vehicles use internal combustion engines which emit high GHG and high toxic emissions. A pathway for low-carbon transport is crucial, consisting the shift from conventional vehicles to electric ones.This talk addresses the global electric vehicle outlook, related technologies of electric vehicles, Vietnam current situation of automotive industry and contribution of low-carbon transport scenarios, in general, and of electric vehicles, in particular, to GHG reduction for Vietnam.

Le Anh Tuan

### A Common-Ground Single-Phase Boost Inverter with Suppressed Double-Frequency Ripple for Photovoltaic Applications

A low-frequency current ripple is introduced at the DC side of the single-phase inverter topology decreasing efficiency in the photovoltaic (PV), and battery systems and degrading the lifetime of an energy storage device. In this paper, a common-ground single-phase single-stage boost inverter for PV applications is presented. The introduced topology consists of three capacitors, one inductor, five switches, and four diodes. The introduced topology has the main features as the common ground between the DC input voltage source and AC output voltage, and voltage boost capability. Furthermore, the low-frequency input current ripple is significantly limited. Besides, the leakage current, which is one of the major problems in grid-connected PV applications, is limited in an introduced inverter. The operating principles, circuit analysis, Mathematical analysis, and PWM control strategy for the introduced inverter are discussed. The simulation results based on PSIM simulation are given at the end of the paper to confirm the feasibility, performance and viability of the introduced topology.

Minh-Duc Ngo, Quynh-Van Nong, Thuy-Ngan Ngo, Hong-Quang Nguyen, Tan-Tai Tran, Seon-Ju Ahn

### A High Step-up DC-DC Converter with Semiconductor Voltage Stress Reduction

Nowadays, switched-inductor and switched-capacitor configurations are widely used for boost DC-DC converters to improve high boost ability. By applying the principle operating of charging and discharging of inductor and capacitor elements in parallel or series connection, it is considered that four diodes, one high voltage rating switch, two inductors are validated to show as a conventional switched-inductor boost converter. In this research, a novel high-boost DC-DC converter based on the switched-inductor technique is introduced. The introduced converter is transformer-less topology and determined by changing the configuration of the conventional switched inductor structure and a semiconductor switch. As a result, the introduced converter can give low voltage rating active switches. Furthermore, the introduced converter is low in cost and achieve higher efficiency with simple topology. The operating analysis of the introduced converter is presented in detail. The simulation results with the output control are presented to verify the analysis.

Hong-Quang Nguyen, Ngoc-Anh Tran, Van-Nghiep Dinh, Vinh-Thuy Nguyen, Minh-Duc Ngo, Joon-Ho Choi

### A Method to Partition Accuracy in Workspace for Robot Arms

This paper introduces a method to partition accuracy for robot arms. In this method, our technique divides workspace into small domains with different accuracy respectively and there are distinct boundaries between these domains. This will provide effective information for engineers to decide which tasks are able or unable to apply robot arms. The accuracy provided by manufactures is only the nominal value, but the real accuracy of robot arms fluctuated in the workspace and transformed according to times. Thus, the method in this paper is useful for determining the varied accuracy in the workspace and time of using industrial robot arms.

Huu-Thang Nguyen, Long Pham Thanh, Jen-Tzong Jeng

### A Novel Method for Shielding Problems with Taking Robust Correction Procedure into Account

This paper presents a robust correction procedure based on the perturbation method to reduce errors around edges and corners related to thin structures via a sub-domain technique. The idea of the method is considered as several scenarios. A sub-domain involving with stranded or massive inductors alone is initially considered. A shielding approximation that neglects end and border effects is then added with an impedance-type condition across a surface. A volume correction is finally introduced to improve the inaccuracies from the shielding approximation. But, this volume correction usually faces with cancellation errors in the calculation of the local fields around corners and curvatures. Thus, in order to treat this inconvenience, a robust correction procedure is developed to take cancellation errors into account. Each sequence of the method is considered separately on its own mesh and domain without depending on other meshes and domains.

Vuong Dang Quoc, Dinh Bui Minh

### A Review on Ultrasonic Stack Modelling

In recent years, the main processing methods for difficult-to-machine materials have focused on the field of ultrasonic-assisted processing. Ultrasonic stack, the key part in ultrasonic equipment, is composed of transducer, booster, and horn. The present literature review aims to provide a broad overview of the recent achievement on the modal assembly of the ultrasonic vibration stack and guide the future development of ultrasonic vibration assisted technologies. With advancement of computer control in ultrasonic machining, this technology can be used for any material in future to achieve world class manufacturing.

Ngo Nhu Khoa, Nguyen Thi Bich Ngoc, Tran Duc Tai

### A Solution to Power Load Distribution Based on Enhancing Swarm Optimization

This paper proposes a solution to the multi-objective problem of optimal power load allocation based on enhancing particle swarm optimization (EPSO) with Pareto. We consider applying to the conventional mathematical model of objective functions to minimize the active power loss of the network, and the power grid operating limitations to the functional importance of the entire model. We implement hybrid chaos optimization with a hierarchical clustering to address the premature convergence of the PSO. The Pareto solution distribution is introduced to achieve the optimum global solution. In the section on simulation, the IEEE 57-bus benchmark is used to test the performance of the proposed scheme. Compared with the other test power system approaches, the results show that the proposed method reduced the net loss of the power system and the consumption of coal from generation sets and conserved energy sources under meeting the power system protection constraints.

Truong-Giang Ngo, Thi-Thanh Tan Nguyen, Thi-Xuan Huong Nguyen, Trinh-Dong Nguyen, Van-Chieu Do, Trong-The Nguyen

### A Study for Determination of the Pressure Ratio of the V12 Diesel Engine Based on the Heat Flow Density to Cooling Water

Improving engine power density by using supercharging system with exhaust gas energy recovery (called an exhaust gas turbocharger) is a trend of improving non-turbocharged base engines in Vietnam. These engines are still capable of being used for a considerable time, but the power generating is not big enough to meet the requirements of improving vehicle maneuverability, especially special vehicles such us Russian or Vietnamese tanks. To determine the maximum level of pressure ratio of the engine according to the engine thermal load criteria, we can use direct and indirect indicators. The content of the paper is to determine the heat flow density for cooling water in the V12 engine according to the different pressure ratios. From that, the maximum level of pressure ratio for the engine is 2.1, but the safety limit allowing the heat to flow to the engine coolant to be guaranteed.

Kien.Nguyen Trung

### A Study of Scissor Lifts Using Parameter Design

Scissor lifts are applied for transporting or lifting various objects. Hydraulic cylinders are used to raise or lower platforms which have many ways to arrange. This study aims to determine appropriate dimensions in design 1X hydraulic scissor lifts. Using symbolic variables to control the dimensions, positions of the cylinder are calculated to ensure the effectiveness of working space and forces in the cylinders. Results obtained from the calculations indicate the practice of numerical methods and can be used to determine optimal dimensions for design 1X scissor lifts.

Anh-Tuan Dang, Dinh-Ngoc Nguyen, Dang-Hao Nguyen

### A Study on Prediction of Milling Forces

The aim of this study is to develop a milling force predicting model which is based on the relation between surface roughness and cutting force resulting from surface milling. Based on the analysis of the available models, the roughness model which has more advantages than others is selected. The newly proposed milling force model is developed based on the roughness model. Eight influential parameters are included in the model such as cutting edge radius, feed rate, side cutting edge angle, end cutting edge angle, radial depth of cut, axial depth of cut, tool diameters and number of cutting edge. Experimental tests by milling C45 steels are conducted to validate the predicted results as well as the realiability of the model. The results show that the maximum percentage errors between prediction and experiments is an average of 16.7%.

Do Duc Trung, Tran Ngoc Giang, Tran Thi Hong, Bui Thanh Danh, Vu Van Khoa, Nguyen Dinh Ngoc, Nguyen Thanh Tu, Vu Ngoc Pi

### A Study on Qualitative and Quantitative Characterization of Machining Quality of Aerospace Composite Structures

Machining CFRP composites generally create defects in machined surfaces which are more irregular than those given by metal machining. Minimizing and controlling the occurrence of damage is a crucial task. To archive that, quantifying damage and correlating it to cutting parameters, as well as mechanical behavior is significant. This study investigates the influences of machining parameters such as spindle speed and feed speed on the ten-point max, Rz. This roughness parameter is recommended to adopt for quantifying the machining quality of CFRPs instead of Ra. Machining defects are identified by SEM observation. Rz values are determined in both longitudinal and perpendicular directions to the machined surfaces. The results show that the combination between high spindle speed and low feed speed can seriously create damage levels. Moreover, it is proved that Rz can well reflect damage evolution, qualitatively identified by SEM observation. This can be concluded that Rz can be a good indicator to quantify machining damage of composite materials instead of using expensive systems which are difficult to be afforded whenever.

Nguyen Dinh Ngoc, Nguyen Thi Hue

### A Study on Prediction of Grinding Surface Roughness

This paper presents a study on the prediction of surface roughness in surface grinding. Based on the results of several previous studies, the relation between the abrasive grain tip radius and the standard systems of grinding wheels and the surface roughness were predicted. Also, the surface roughness when surface grinding SKD11, SUJ2, and 3X13 steel by Al2O3 and CBN grinding wheels was anticipated. The predicted surface roughness values were found to be close to the experimental values. In addition, the average deviation between the predictive results and the experimental results was 15.11% for the use of Al2O3 grinding wheels and 24.29% for the case of using CBN grinding wheels.

Do Duc Trung, Nhu Tung Nguyen, Hoang Tien Dung, Nguyen Van Thien, Tran Thi Hong, Tran Ngoc Giang, Nguyen Thanh Tu, Le Xuan Hung

### A Vision-Based Measurement and Classification System for Robot Arm Under Controlled Lighting Condition

This paper presents development of a measurement and classification system for robot arm using machine vision under controlled lighting environment. The proposed system uses a single camera as a sensor for measuring and classifying objects which are bolts and nuts. Using image processing and analysis, characteristics of objects was extracted and area of blob in binary image also was calculated for classification process. For coordinate calibration process, the quadratic transformation and regression analysis were used to determine relationship between image coordinate and the world coordinate. Experiment results showed that the proposed system can measure and classify the components exactly of 100% from all samples tested and measurement errors are suitable with the system which applied to a robot arm.

Quang-Cherng Hsu, Ngoc-Vu Ngo, Thanh-Long Pham, Quoc-Khanh Duong, Duc-Vuong Vu

### About a Viewpoint of Calculating Spatial Dimensional Tolerance Chains According to Structure Group of a Parallel Robot

In robotics technology, tolerance design is a part of mechanical design and determines the final product quality. The spatial dimensional chain problem of the parallel structure with component links having an active assembly and the closed link having a given error is a complex one. Determining the relationship between the end effector tolerances and component link tolerances of each leg in general form is the basis for digitizing the problem. Calculating the initial approximation of tolerance for other structures in the group based on the sample solution has the meaning of deciding time and quality of calculation. This paper proposes a hypothesis that it is always possible to determine a reasonable initial approximation based on a sample solution. Therefore, the process of calculating tolerances of the component kinematic parameters of parallel industrial robots is significantly shortened.

Thuy Le Thi Thu, Trung Trang Thanh, Huu-Thang Nguyen, Long Pham Thanh

### Adaptive Algorithm for Servo System Using Linear Electric Motor

This article aims to build the construction of a mathematical model of a linear motor for moving the valve of an electro-hydraulic drive. First, an analytical description of its non-linear traction characteristic is given as well as the resulting reaction from the action of electromagnetic force and the elastic force of the center spring. Second, the Adaptive algorithm of servo control based on the Lyapunov theorem is built and an analysis of the effectiveness of the adaptive algorithm with the change of the servo system’s parameters. Simulation results on the model of the servo system with the controller in the MATLAB-Simulink software package are presented to demonstrate the effectiveness of the proposed approach in this paper.

V. E. Kuznetsov, Phan Thanh Chung, Nguyen Thi Ha, Nguyen Hoang Ha

### Adaptive Sliding Mode Control for a 2-DOF Robot Arm in Case of Actuator Faults

The paper presents an adaptive sliding mode controller for a 2-DOF robot arm suffering actuator faults. The type of actuator faults considered in this study is the proportional degradation of torque. The robot model is set up with unknown factors representing the degree of the actuator torque fault. Based on this model, an adaptive sliding mode methodology is designed to tolerate the faults. The system stability is guaranteed according to the Lyapunov approach. The adjustable controller coefficients can be adapted to greater values of unknown bounds, which satisfies the Lyapunov criterion. A performance comparison between the proposed control fashion and a popular robot controller is carried out via the MATLAB/Simulink simulation environment. The results show that the proposed controller can satisfactorily steer the joint responses following the desired trajectories in the faulty state with reasonable degrees of torque loss.

Le Ngoc Truc, Nguyen Phung Quang

### An Energy-Efficient Combination of Sleeping Schedule and Cognitive Radio in Wireless Sensor Networks Utilizing Compressed Sensing

Conventional wireless sensor networks (WSNs) have been well exploited with many applications and also numerous techniques for improvements. Recently WSNs employ muti-media services that require more resources including frequency bandwidth and transmission rate. This encourages more exploration to support the networks to approach the increasing demand in quality of service. This paper shows an investigation to combine some techniques to meet some requirements. Cognitive radio (CR) have been known to use frequency band effectively. Compressed sensing (CS) applied in WSNs reduces the data transmission in the networks. Sleeping schedules for sensor nodes in such networks are also considered to save energy while still provide enough data needed. This work is a combination that provide analysis of network models, simulation results and shows promise for future WSNs.

Minh T. Nguyen, Thuong T. K. Nguyen, Keith A. Teague

### An Enhancing Grasshopper Optimization for Efficient Feature Selection

Grasshopper optimization algorithm (GOA) is a new swarm intelligence algorithm that simulated a model of locust swarm behavior for optimization problems. Still, it has drawbacks, e.g., falling into a local optimum and slow convergence. This paper suggests a method enhancing GOA optimization (namely EGOA) based on an adaptive weight coefficient and nonlinear parameters to balance the global exploration and local development capabilities, to promote the convergence speed, and to avoid trapping of falling into a local optimum the algorithm. In the simulation experiment, four benchmark test functions and the feature selection problem are used to prove that the improved strategy used in the proposed method can effectively enhance the precision and convergence speed of the GOA. The experimental results on seven UCI datasets show that the proposed method can effectively provide the best selection features for increasing classification accuracy.

Trong-The Nguyen, Shi-Jie Jiang, Thi-Kien Dao, Truong-Giang Ngo, Thi-Thanh-Tan Nguyen, The-Vinh Do

### An Evaluation of B-Spline for Synthesis of Cam Motion with a Large Number of Output Conditions

In the cam design process, cam motion functions play an important role due to affect not only kinematics but also the dynamics of the cam-follower systems. However, the selection of cam motion functions has been poor so far. This study aims to evaluate B-spline for the synthesis of cam motion with a large number of output conditions. The procedure for determining the cam motion was investigated. In addition, the comparison of the motion diagram between the cubic and quintic B-spline was also proposed. Moreover, Fourier analysis was used to examine the response of the kinematics in cam-follower systems. The results demonstrate that using quintic B-spline can be given good characteristics of the cam motion.

Nguyen Thi Thanh Nga, Nguyen Van-Sy, Nguyen Thi Bich Ngoc, Vu Thi Lien

### An Experimental Study on Vibration-Driven Locomotion Systems Under Different Levels of Isotropic Friction

This paper shows experimental analysis results of the study on vibration-driven locomotion system, which can be applied in capsule robots. The experimental apparatus provided a capacity of varying friction force when keeping the weight of the whole system unchanged. Twelve experimental sets with 16 runs for each set were implemented, providing a deep insight of the system behavior, both in progression rate and the relative motions of the masses. The experimental data revealed that, the force ratio between the excitation magnitude and friction level would not be totally correct to present the excitation effects in modeling the system. The level of friction force may have a significant effect on not only how fast the system move, but also which direction of the progression. The new findings would be useful for further studies on the design and operation of vibration driven locomotion systems.

Ngoc-Tuan La, Quoc-Huy Ngo, Ky-Thanh Ho, Khac-Tuan Nguyen

### Analysis of Milling Chatter Vibration Based on Force Signal in Time Domain

Chatter is problematic during metal cutting process. It destroys the surface finish and reduce productivity and quality of productions. Therefore, prediction and identification of chatter vibration are needed to determine the range of stable cutting conditions. In this paper, the force signal in time domain is used to analyze the behaviors of the milling chatter vibration. The largest Lyapunov exponent index which can describe the different nonlinear characteristics of dynamical system behaviors is used as an effective indicator to distinguish the stable and unstable cutting conditions. The proposed chatter detection approach has been successfully validated by experiment.

Minh-Quang Tran, Meng-Kun Liu, Quoc-Viet Tran

### Analytical Study of the Power Parameters of Electric Traction Drive for Modern Vehicles

The development of electric freight transport is becoming increasingly important against the backdrop of growing environmental problems, especially in megacities. The selection of the actual parameters of the power plant for electric freight vehicle is important here. This article analyzes the implemented projects in the world. The information gains particular relevance against the background of the absence of industrial production of power plants in the Russian Federation. The paper presents data on freight vehicles with a traction electric drive and deduces patterns in the value of the power of the used electric motors relative to the mass of the car in order to clarify the most popular standard-size series. This study was carried out with the aim of a feasibility study of models of electric motors for commercial vehicles proposed for launch into serial production.

Aleksey Kolbasov, Kirill Karpukhin, Dmitry Sheptunov, Povalyaev Andrey, Nguyen Khac Tuan, Nguyen Khac Minh

### Automatic Extraction and Welding Feature Recognition from STEP Data

Feature recognition has been considered as an important bridge between CAD and CAPP in process planning for welding. These recognition data can be used as input data not only for generating welding tasks in process planning but also for programming work of welding industrial robot without using teach pendant. This paper introduces an effective method to extract and recognize welding features from STEP file which can be provided by any 3D CAD system. The computer program quickly extracts data from various strings in the STEP file, saves them in the database and recognizes features for welding by the developed algorithm. The welding paths with detailed geometry characteristics are recognized in a short time. All recognition results are stored in the database for further processes. A case study is used to verify the validity of the recognition method.

Lan Phung Xuan, Linh Tao Ngoc

### Characterization of Gelatin and PVA Nanofibers Fabricated Using Electrospinning Process

Nanofibers has been recently received tremendous attention from researchers due to its advantages. Among the fabrication methods for nanofibers, electrospinning appears to be an intriguing technique, allowing the fabrication of nanofibers in a simple and inexpensive way. In this paper, we prepared and fabricated nanofibers using the electrospinning process with two polymers: gelatin and PVA. The process and the fabricated fibers were examined under scanning electron microscope. The effect of the polymeric concentration was also studied. The experimental results indicate that nanofibers were successfully fabricated, and higher polymer concentration leads to the uniformity of the fibers. In addition, the nanofiber mat with silver nanoparticles was successfully fabricated, opening the potential for medical applications of the fabricated fibers.

Cuong Nguyen Nhu, Nhung Vu Thi, Nam Nguyen Hoang, Thao Pham Ngoc, Trinh Chu Duc, Van Thanh Dau, Tung Bui Thanh

### Choice of Selection Methods in Genetic Algorithms for Power System State Estimation

The state estimator plays an important role in power system operation. It is used to monitor state parameters, thereby it helps the operators make control decisions when the parameters exceed the permissible limits to ensure the system operate in a normal and secure state. To solve this problem, we can use artificial intelligence methods such as genetic algorithms. The genetic algorithms consist of three main operators: selection, crossover, and mutation. Among them, the selection of individual parents plays an essential role as it affects the performance of the algorithm. This paper studies the effect of selection methods on results of power system state estimation. The results depend significantly on the choice of selection methods and show that the roulette wheel selection is the best choice.

Thanh-Son Tran, Thi-Thanh-Hoa Kieu

### Collision-Free Path Following of an Autonomous Vehicle Using NMPC

This paper deals with the obstacle avoidance problem for an autonomous vehicle using NMPC (Nonlinear Model Predictive Control) while following an a priori given path. The repulsive potential of the operating space is constructed from the bounded convex regions describing the static obstacles for collision-free navigation. The contribution lies in using the Hausdorff distances among the obstacles and the agent in order to activate/inactivate the repulsive potential field. This potential field component is introduced in a NMPC framework to penalize collision. This proposal shows good results in simulations and comparisons with our previous work.

Ngo-Quoc-Huy Tran, Ionela Prodan, Nguyen-Duy-Minh Phan

### Compare the Efficiency of the Active Filter and Active Rectifier to Reduce Harmonics and Compensate the Reactive Power in Frequency Controlled Electric Drive Systems

Currently, frequency converters using diode rectifiers generate a lot of harmonics, which adversely affect the quality of the grid and the durability of electrical equipment. On the other hand, asynchronous motors that consume a large amount of reactive power of the source cause losses on the grid and reduce the power factor at the input of the converter. Therefore, researching the method of using active filters at the input of frequency converters with diode rectifiers will reduce current harmonics and compensate reactive power for the grid. The active filter will produce harmonics with a phase angle inversely to the phase angle of the harmonics generated by the load, which will suppress most high-order harmonics. The frequency converters use active rectifiers with a direct power control method so that the reactive power q = 0 ensures the standard sine current at the input, the power factor equals 1, there is the stability of a DC voltage and the power is exchanged in two directions between the motor and the grid. The paper compares the effectiveness of the two methods when considering the load as three asynchronous motors that work in different modes such as motor mode and generator mode. The research results are verified by Matlab & Simulink software.

Le Van Tung, Pham Thanh Long, Ngo Van An, Bogdan Vasilev

### Comparing the Application of Gas Sensor Fabrication of Nanomaterials ZnO Fabricated by Hydrothermal and Chemical Vapor Deposition Method

In this report, we introduce a method of ZnO nanomaterials fabrication. Particularly, we study the structure of the material, compare the structure of the fabricated materials. The size of the created material is about 30–40 nm in diameter, the length is from 1 to 10 nm. The material responds well to NO2, the resistance of the material changes 25 times with 10 ppm of NO2 at 205 °C. Gas-sensing characterizations revealed that the ZnO sensors exhibited a relatively high response to sub-ppm NO2 with excellent stability of switching from NO2 to air without significant response reduction.

Hoang Van Han, Dao Huy Du, Do Anh Tuan

### Convergence Parameters for D-Type Learning Function

Two sufficient convergence conditions of D-type iterative learning function for practical applications are proposed in this paper. In these two convergence conditions, it is not required absolutely, that the relative degree of controlled repetitive plans has to be equal one, which is happened consistently in other convergence conditions. Hence, their opportunity for practical application range becomes wider. Some illustrative simulations afterward have confirmed this affirmation.

Cao Thanh Trung, Nguyen Thu Ha, Tran Kim Quyen, Nguyen Doan Phuoc

### Current Harmonic Eliminations for Seven-Phase Non-sinusoidal PMSM Drives applying Artificial Neurons

This study is to deal with unwanted current harmonics in rotating (d-q) frames of a 7-phase non-sinusoidal permanent magnet synchronous machine (PMSM) in a wye-connected winding topology. The machine is supplied by a 7-leg voltage source inverter (VSI) fed by a DC-bus voltage. In control, current responses are expected to properly track their references. However, several unwanted harmonics of the non-sinusoidal back electromotive force (back-EMF) and the inverter nonlinearity generate unwanted harmonic components in d-q currents. These current harmonics cannot be nullified by controllers such as conventional proportional-integral (PI) controllers. Consequently, the current responses cannot track their references. In this study, a combination of conventional PI controllers and simple adaptive linear neurons (ADALINEs) is proposed to eliminate these current harmonics, improving current control quality of the drive. The effectiveness of the proposed control structure is verified by experimental results.

Duc Tan Vu, Ngac Ky Nguyen, Eric Semail, Thi Thanh Nga Nguyen

### Design and Some Experimental Results of the Robust Current Controller of Doubly-Fed Induction Generator in Wind Power Plant with the Backstepping Technique Based Disturbance Observer

With the increasing requirements of quality of electrical network, now grid codes determine that wind turbine connected to the network, especially for wind farm, must be able to connect to the grid during three phase voltage dips, and must be able to support the voltage of the grid during and immediately following the grid fault by supplying reactive power to the network, that guarantees the stability of the network. The robust current controller of doubly fed induction generator in wind power plant with the Backstepping technique based disturbance observer has solved the above problem when the voltage sags to the 15% of its normal value. The results have been verified on experiment system based on the dSpace Multi Processors ALPHA-COMBO system.

C. X. Tuyen, N. T. Huong

### Design and Some Experimental Results of the U-Type Permanent Magnet Three-Phase Linear Motor Based Position Control System with the Backstepping Technique Based Disturbance Observer

Nowadays, permanent magnet linear motors are widely used in high accuracy CNCs, because they make the linear moving without the mechanical system, that transfers rotating moving to linear moving, therefore the accuracy in position control of the system is improved. Among them, U-type permanent magnet three-phase linear motors are more widely used because there are not attractive forces in these motors and the thrust force is high. However, the nonlinearity of the motor and the force disturbances that are caused by the end effect, load, slot tooth, high order harmonic waves still reduce the accuracy in position control of the system. In order to solve this problem, this paper presents the design of the U-Type permanent magnet three-phase linear motor based position control system with the Backstepping technique based disturbance observer. The proposed position control system is experimented on the DSP based experimental system, which uses DSP TMS 320F2812. The experimental results show that the performance of the proposed position control system has high accuracy, that meets the commands of the high precision CNC machines in the industry.

C. X. Tuyen, N. T. Huong

### Detail Design of IPM Motor for Electric Power Traction Application

This paper deals with the electromagnetic and thermal analysis of an interior permanent-magnet (IPM) synchronous motor with V shape used as traction drive in a medium commercial electric vehicle (EV) according to the traction requirements of the electric vehicle under normal operating conditions and overload conditions or peak power. The key dimensions were calculated on an analytical program by Matlab. The finite element method (FEM) simulation model of the IPM motor was built by using SPEED software. The influenced geometric structures of the IPM motor including the PM dimensions and skewed PMs on electromagnetic torque were investigated, and the temperature distribution of the motor under rated operating condition and the condition of maximum speed were calculated. Finally, the thermal simulation results of the IPM motor running in various operating modes were investigated and the medium commercial electric vehicle driving applications were required. The contributions of this paper are optimal V angle of magnetic and skew angle slot to minimize torque ripples for a 60 kW IPM 12P/72 slots.

Bui Minh Dinh, Dang Quoc Vuong

### Detecting Common Web Attacks Based on Machine Learning Using Web Log

SQL injection (SQLi), Cross-site Scripting (XSS) attacks have long been considered major threats to web-based applications and their users. These types of web attacks can cause serious damage to web applications and web users, ranging from bypassing authentication systems, stealing information from databases and users, to even taking control of server systems. To cope with web attacks, many measures have been researched and applied to protect web applications and users. Among them, the detection of web attacks is a promising approach in the defensive layers for web applications. However, some measures can only detect a single type of web attacks, while others require frequent updates to the detection rule sets, or require extensive computational power because of using complex detection methods. This paper proposes a web attack detection model based on machine learning using web log. The detection model is built using the inexpensive decision tree algorithm and it does not require frequent update. Our experiments on a labelled dataset and real web logs show that the proposed model is capable of detecting several types of web attacks effectively with the overall detection accuracy rate of 98.56%.

Xuan Dau Hoang

### Determination of Kinematic Control Parameters of Omnidirectional AGV Robot with Mecanum Wheels Track the Reference Trajectory and Velocity

Nowadays, in order to save the floor space of the production workshops, the mecanum wheels have been applied to the design of Automated Guided Vehicles (AGV) robot to create highly flexible and omnidirectional AGV robot. Omni-directional robotic platforms have vast advantages over a conventional design in terms of mobility in congested environments. These environments are commonly found in factory workshops offices, warehouses, hospitals and elderly care facilities. To be able to control these robots in any given trajectory, it is necessary to set up the kinematic control parameters. The paper presents the method of establishing the kinematic equation of omnidirectional robots by the centre of instantaneous velocity, thereby determining the control parameters of AGV robot following a reference trajectory. In addition, the authors also designed the robot’s motion trajectories using the NURBS curve to solve the robot’s trajectory planning problem according to different application scenarios of modern industrial production.

Trinh Thi Khanh Ly, Nguyen Hong Thai, Le Quoc Dzung, Nguyen Thi Thanh

### Development of New Method for Choosing Standard Components Subject to Minimal Cycle Time and Minimal Sum of Purchasing Cost

An assembly line is made from different machines and a machine can contain different stations and function carriers. Each function carrier even is performed by different standard function carrier variants. The designer can calculate and select the available function carrier variants to construct into a new machine. The advantages of using the available function carriers are the low cost, reduction of design and manufacture time and improvement of machine working life. If a machine has n function carriers, each function carrier contains m variants. Hence, there are nm combinations to make the machine. The number of these combinations increase rapidly according to a large number of function carriers. To select the suitable function carrier variants subject to optimal cycle time and total purchasing cost, the designer cannot manually select the best solution from so many options. Nowadays, there is no effective method to solve this problem. To solve this problem, this paper will set up the operating cycles for an assembly machine and establish linear optimization in standard form for choosing the best function carrier variants from the given database. To minimize both the cycle time and total purchasing cost of an assembly machine, the linear programming must contain two stages and run in sequence. The large linear optimization is programed and solved by using the IBM ILOG CPLEX Optimizer. The optimal results will be exported to tables in a database. This makes the designer easy evaluate and select the best solution. In addition, designer can expand the scope of study to design other machines.

Tan Nguyen Dang, Manh Cuong Nguyen

### Dust Emission During Machining of CFRP Composite: A Calculation of the Number and Mass of the Thoracic Particles

Machining of CFRP composite creates many kinds of induced damage like delamination, fiber pullout, etc. these kinds of damage strongly are associated with appearance of dust generated during machining. The small dust particles can be inhaled by operators in machining areas, which can make them get some diseases. However, there have been few studies dealing with this problem. This study aims to investigate the influences of cutting parameters (cutting speed, feed speed and depth of cut) on the number and mass of thoracic which possess aerodynamic diameter particles lower than 32 µm. Dust particles were collected using a dust monitor. The results show that when cutting speed increases the number of thoracic particles increases. Moreover, an increase of feed speed or depth of cutting leads to reduce the number and mass of thoracic particles.

Dinh Nguyen Ngoc, Thi Nguyen Hue, Bui Van Hung, Vu Duy Duc

### Dynamic Surface Control of the Axial-Flux Permanent Magnet Motor with Speed Sensorless Algorithm

The permanent synchronous motor drive system incorporates magnetic bearings to perform speed control and balance rotor control between the two stators. The paper designed a system to perform adjusting motor speed sensorless based on measured current and voltage components. The electromotive force (back-EMF) generated in the stator is estimated by a High-Gain observer. The angular position and velocity rotor are calculated through the α-β components of the back-EMF. The motor drive is built in a vector control structure based on the rotor flux. In which based on the Lyapunov stabilization function, the dynamic surface control method is used to calculate the axial position and speed controller of the motor. Simulation results show that the proposed controller and observer are fully capable of meeting the system control requirements.

Manh Tung Ngo, Quang Dang Pham, Huy Phuong Nguyen, Tung Lam Nguyen

### Edge-Based Object Pose Estimation Using Differential Evolution Algorithm

The paper presents an object-tracking method to estimate three-dimensional position of objects based on an edge image and the object’s 3D model. The system uses differences between a chamfer matching map and 2D edge gained from a pose hypothesis as the fitness function. Differential Evolution algorithm uses the fitness function in order to find the most suitable position of objects. The experiments with the initialization task were carried out. The results of initialization problem proved the effectiveness of our method in solving the most difficult problem of object tracking. The correct poses were found in reasonable runtime. After correct initialization, the searching space is significantly reduced, as the more effective of the method could track the object in continuous frames.

Ngoc Linh Tao, Lan Phung Xuan

### Effect of Changing Grounding Mode to Reduce Power Loss on Lightning Ground Wire by Induced Current - Northern Vietnam Overhead Power Transmission Line

In Vietnam, the overhead power transmission lines are usually equipped with lightning ground wires, include optical fiber composite ground wire (OPGW) and common ground wire (CGW). Both lightning wires are grounded at each tower to ensure safety for transmission line but directly affect the power loss, caused by electromagnetic induction. Therefore, the calculation of quantitative power loss shows the urgent necessity to reduce the loss, by changing the grounding mode of lightning ground wire. Both field measurement and ATP-EMTP simulation of induced current and voltage of lightning ground wires in transmission lines are carried out in this paper. The results allow proposing a solution to reduce the loss on the lightning ground wire of power transmission grid.

Nhat Tung Nguyen, Xuan Phuc Nguyen

### Electromagnetic Design of Synchronous Reluctances Motors for Electric Traction Vehicle

The paper presents comparative performances of different rotor structure synchronous reluctance motors used for electric traction in automotive application. The electrical machine under study in this paper is a synchronous reluctance machine (SynRM) with 8 poles and 48 slots. The study design has implemented two V and U shape flux barriers with 4 layers. Pure Synchronous Reluctance motors potentially operate at high speed due to a cost-effective rotor compared to PM and induction motors. In this paper, thermal simulation and mechanical stress was also investigated to evaluated flux bar or sizing of the radial ribs. The approach leads to an original positioning of the radial ribs able to preserve the performances of the motor at high operating speed enhancing the mechanical integrity of the rotor. Some significant contributions of this study are new 4U layer barrier rotor and mechanical stress of ribs and bridges at maximum speed.

Bui Minh Dinh, Do Trong Tan, Dang Quoc Vuong

### Enhancing Accuracy of Surface Roughness Model Using Box-Cox Transformation in Surface Grinding AISI 5120 Alloy Steels

The aim of this paper is to present a research study on enhancing the model accuracy of surface roughness when surface grinding. The used material is this study is AISI 5120 alloy steel and the grinding wheels are made of CBN. The experimental matrix is prepared according to response surface method in terms of Central composite design. Four cutting parameters, i.e. workpiece speed, feed rate, depth of cut, and dressing depth, are selected to investigate their influences on the surface roughness. Moreover, the interactions between the cutting parameters are also considered. Regression models for predicting surface roughness are suggested. Box – Cox transformation is applied to transform the non-normal distribution data to the new ones exhibiting normal distribution shapes. The results show that the new model (using Box – Cox transformation) predicts surface roughness better than the old model (without using Box – Cox transformation) does.

Do Duc Trung, Nguyen Dinh Ngoc, Tran Thi Hong, Bui Thanh Danh, Nguyen Thanh Tu, Tran Ngoc Giang, Nguyen Thi Quoc Dung, Vu Ngoc Pi

### Ensemble of Deep Learning Models for In-Hospital Mortality Prediction

Using machine learning in health care for supporting doctors to diagnose diseases is receiving a lot of research interest. Currently, many hospitals use Electronic Health Records (EHR) to store medical records, which is an extremely valuable data source for machine learning. This paper uses the Medical Information Mart for Intensive Care (MIMIC-III) dataset to solve the problem of predicting mortality in hospitals. We have proposed standardizing numerical attributes in two ways: normalizing using mean and variance on Training set and standardizing using mean and variance according to 48 h of each sample. Neural network architectures based on CNN models have been proposed and tested. Ensemble technique has been applied to each parameter representation type and each model type. Test results show that the ensemble method has improved the performance of the system. Test results on the Test set achieve AUROC is 0.851, AUPRC is 0.452 and min (Se, + P) is 0.459.

Quang H. Nguyen, Quang V. Le

### Evaluating the Impact of Demand Response in Planning Micro-grids Considering Uncertainties

This study proposes a planning framework to optimize the configuration of grid-connected micro-grids under the impact of the demand response program. The uncertain parameters are integrated into the optimal model by different discrete states that are divided by the clustering technique from the probability distribution functions. A life cycle cost objective function including investment cost, operation cost, energy cost, and emission cost of the system together with constraints are presented in a mixed-integer programming model. The simulation result by GAMS/CPLEX for the test micro-grid shows the effect of the proposed model for micro-grids planning problems which include uncertain parameters. Moreover, the proposed model allows for analyzing the performance of the demand response program during the planning period. By performing the demand response program, both life cycle cost and invested power of RS together with emission decreased.

V. V. Thang, N. H. Trung

### Evolutionary Tuning of PID Controllers for a Spatial Cable-Driven Parallel Robot

The tuning technique of a proportional–integral–derivative (PID) controller for a spatial cable-driven parallel robot by using evolutionary algorithms has not been investigated yet so far. Thus, this study proposes a tuning technique of gains of PID controllers by using three following evolutionary algorithms (EAs): Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and Differential Evolution (DE). The objective function of optimization is the integral of the square error (ISE) and the minimum energy consumption. The performances of these algorithms are studied and are compared to each other based on responses of the end-effector and convergence characteristics of best values, mean values, and standard deviations. The results reveal that all GA, DE, and PSO give good performances. However, PSO and DE are better compared to GA. The GA needs more generations to achieve optimal gains while PSO and DE need less time to find out the optimal gains.

Sy Nguyen-Van, Diem Thi Thu Thuy, Nga Nguyen Thi Thanh, Ngoc Nguyen Dinh

### Experimental and Numerical Characterization of Mechanical Behavior for the Corrugated Cardboard

In this paper, the elasto-plastic model in plane stresses was presented to characterize the mechanical behavior of paper sheets of double corrugated cardboard. Tensile tests of three types of paper were performed to obtain the three force-displacement curves (MD, CD and 45°) for each type of paper. By using the Abaqus calculation software and the SiDoLo identification software, the 11 parameters of the elasto-plastic model for the skins and corrugations that constitute the corrugated cardboard were determined. These parameters of the elasto-plastic model allow us to model the corrugated cardboards in 3D structure by using the user subroutine VUMAT implemented in Abaqus/Explicit. The simulation and experiment of crushing and bending of double corrugated cardboards between the mortar and pestle system were carried out and have proved the precision and effectivity of the present model. The present model allows us to predict the mechanical behavior of orthotropic composite plates with the type corrugated cardboards without carrying out the experiments.

Duong Pham Tuong Minh, Dao Lien Tien, Nguyen Quang Hung

### Experimental and Numerical Investigations into Evaporation Rates of Some Fuels Utilized in Aviation Gas Turbine Engines

Fuels utilized in aviation gas turbine engines are multi-component and supplied into the two-phase flow environment (fuel and air) under high temperature and pressure conditions of the combustion chamber. Examining aviation fuel evaporation in these conditions is quite challenging. Currently, there are different models available in the literature for examining evaporation characteristics for both mono- and multi-component drops in the multi-phase flow medium. However, a scientific approach to select suitable models for practical fuels such as the ones utilized in aviation gas turbine engines is scarce. In this paper, an experiment has been conducted under quiescent droplet conditions, zero velocity gas flow, and at the atmospheric pressure. Combining the experimental outcomes and evaporation rates obtained from different models, suitable models for computing evaporation rates of aviation fuels is analysed and suggested. The analysis shows significant gaps in evaporation rates when using different models. It is suggested that using an equilibrium model like the M2 model is one option to provide reasonable evaporation rates for small droplets (e.g. <0.1 mm). However, further studies are required to provide a fair conclusion for modelling aviation fuel drops when accounting for multi-component issues as well as variable drop sizes.

Nam V. T. Pham, Kien T. Nguyen, Thin V. Pham, Phuong X. Pham

### Experimental Evaluation of the Performance of Oil-Based Nanofluids in the Grinding of Ti-6Al-4V Alloy

The increasing demand for better machining performance has promoted the application of nanofluids in cutting operations. In this study, the grinding of Ti-6Al-4V (Ti64) titanium alloy is evaluated under different cooling conditions such as dry cutting, emulsified fluid, synthetic oil fluid, and synthetic oil-based nanofluids. Mixing 0.25% exfoliated graphite nano-platelets (xGnP) and 1% hexagonal Boron Nitride (hBN) nano-particles with the synthetic oil produces two types of nanofluids. The grinding performance under different cooling modes is investigated in terms of grinding force, force ratio, and specific energy. The experimental results show that all oil-based coolings generally present lower grinding forces in comparison with dry cutting. The addition of xGnP and hBN nano-particles into the base fluid further reduces the grinding forces because of the polishing effect and the formation of a lubricating film in the cutting zone to improve the lubrication properties.

Trung Kien Nguyen, Hung Trong Phi, Got Van Hoang, Tam Ngoc Bui, Son Hoanh Truong

### Fault Diagnosis for the Short-Circuit Fault of the Single-phase Five-Level VIENNA Active Rectifier

The five-level VIENNA rectifier is very well suited to the short-circuit switch fault. However, this type of fault causes a distortion in the input phase current, one flying- capacitor to be discharged to zero and the other to be charged until corresponding output capacitor voltage. There is a big difference between two output capacitor voltages and decreases the apparent frequency of input converter voltage. Therefore, the proposed fault diagnosis is necessary to prevent further failures, and to analyze the impact of fault on system performance. This paper analyzed the behavior of the ON- fault in the single phase five-level VIENNA rectifier and proposed a fault diagnosis and integrated reconfiguration control. The effectiveness of the proposed fault diagnosis and reconfiguration control methods are verified through simulation results.

Pham Thi Thuy Linh, Nguyen Ngoc Bach, Doan Van Binh

### Feedforward Based Dual Loop PI Controller for 400 Hz Ground Power Unit

In this paper, a new configuration of 400-Hz inverters based on unipolar Sinusoidal Pulse Width Modulation (SPWM) is proposed for the Ground Power Unit (GPU) in aerospace industry. In this model, instead of using rectifiers fed by the AC electric grid, a lithium battery is employed for improving the flexibility and reliability of the power supply. Then a transformer is used in combination with a capacitor to serve as LC filters in order to reduce the volume/size of the GPU at the same time lower the production cost. In the control scheme, a dual-loop PI controller is proposed in which the coupling components in the model of three-phase inverters are analyzed and handled by feed-forward techniques to simplify the transfer function. Then, the stability of the proposed system is analyzed and the control strategy is designed with digital processors. The proposed system is tested in testbed systems with a 90-kVA, 3-phase, 215-V GPU. The simulation and experiment result show the advantages and effectiveness of the proposed system with relatively small voltage deviation and total harmonic distortion (2.56%).

Son Tran Que, Dich Nguyen Quang, Minh Y. Nguyen, Quy Do Ngoc, Phu Do Ba

### Force-Velocity Relation of Dampers in Horizontal Washing Machines

In this study, a model of the friction force of dampers in a horizontal washing machine is proposed. A MATLAB program is used to determine the parameters for force-velocity relation curve according to Tustin model based on the experimental data of dampers. The two degree of freedom system of horizontal washing machines with new friction model is simulated. The validation of the model with the proposed friction force was verified by comparison with experimental results and previous studies. The result shown that the damping model with the force-velocity relations proposed for more accurate results especially when examining the vibration properties of the suspension when the washing machine works at high speed.

Nguyen Thi Hoa, Ngo Nhu Khoa

### Gear Fault Classification Using the Vibration Signal Decomposition and Neural Networks

This paper proposes a new procedure for classification of gear faults such as normal gear (NG), chipped gear (CG), broken gear (BG), and synthesis fault (SF) using a multi-layer perceptron neural network (MLP network). Measured vibration signals are processed by the wavelet packet transform (WPT) with the Daubechies wavelet function. The standard deviation of wavelet packet coefficients, called feature vector, achieved from WPT is one of the most significant parameters to fault classification. In this study, the wavelet packet decomposition applied up to the four levels, giving 16 signal coefficients with their corresponding standard deviations used as 16 input of MLP network. There are four neurons of the output layer in the MLP network obtained from four gear faults. The classification result shows that the proposed approach can be used to detect and identify gear faults in transmission system automatically.

Nguyen Trong Du, Nguyen Phong Dien

### Genetic Algorithm Based Optimization of Cutting Parameters in CO2 Laser Beam Cutting of Cow Leather

Laser cutting provides better and affordable cutting of intricate geometries with stable cutting quality in economically best way. In the present study, an effort was made to utilize genetic algorithm (GA) for the minimization of kerf width and maximum dimensional accuracy on cutting of cow leather. The investigation was carried out with different process parameters such as power (w), cutting speed (mm/s) and time (sec). The different geometries (square, rectangle, hexagon, triangle) of cow leathers were taken as specimens. The optimization machining parameters to acquire minimum overcut was done by genetic algorithm. It has been found that the proposed algorithm could provide better performance measures on leather cutting of cow leather.

Thangaraj Muthuramalingam, Swaminathan Vasanth, Sanjeev Gupta, Vu Ngoc Pi

### Influences of Cutting Parameters on Surface Roughness During Milling and Development of Roughness Model Using Johnson Transformation

The current study presents the influences of cutting parameters (cutting speed, feed rate, and depth of cut) on the surface roughness during milling usingC45 steel. The experimental plan of the study is carried out by applying Box-Behnken technique. The surface roughness is predicted by two proposed models, one of which is developed based on Johnson transformation. The results report that the Johnson-transformation-based model produces better prediction of the surface roughness than the other.

Do Duc Trung, Nguyen Dinh Ngoc, Tran Thi Hong, Vu Van Khoa, Nguyen Thanh Tu, Tran Ngoc Giang, Nguyen Thi Quoc Dung, Vu Ngoc Pi

### Influence of Random Fiber Length on Macroscopic Properties of Short Fiber Reinforced Composites Due to Microscopic Physical Uncertainty

For the multiscale simulation of advanced materials with hierarchical, heterogeneous, and random microstructures such as fibrous composites by finite element method, mathematical homogenization method has been extended to the stochastic multiscale method. In this paper, a stochastic perturbation-based homogenization method was used to predict homogenized properties of short fiber reinforced composites with random fiber length, random orientation, and random mechanical properties of fiber and matrix resin. For demonstration, a random short fiber reinforced plastic was investigated considering thirteen random physical parameters and two ways of approximation of statistically measured fiber length distributions. The influences of each uncertainty factor on the homogenized properties of the material were observed. The results show that the homogenization properties are likely orthotropic even though the fiber and matrix are considered as isotropic materials. The material is stronger in the direction where the fibers are mostly longitudinal. Each component of the homogenized properties is resulted in a probability density function under the influence of the random physical parameters. Besides, the scatter of the properties was predicted due to very slight difference between two fiber length distributions.

Tien-Dat Hoang, Nhu-Khoa Ngo, Dinh Ngoc-Nguyen, Van-Truong Nguyen, Tuong Minh Duong Pham, Thi Thanh Nga Nguyen, Viet Dung Luong

### Kinematic Analysis of the Class 2 Degree-of-Freedom Planar Parallel Mechanism via GRG2 Algorithm

This paper presents a simple and effective method to obtain joint inputs needed to attain any point in the reachable workspace of the class two-degree-of-freedom planar parallel manipulators, which are based on five rigid links and five single degree of freedom joints - revolute and prismatic joints. By using the close-loop vector theory, the kinematic equation is obtained and changed into a nonlinear optimization problem with constraints to the RosenBrock-Banana objective function form. The optimum solutions of the inverse and forward kinematic problem were implemented with a Generalized Reduced Gradient algorithm. The method has been applied to solve the kinematic problem to a representative mechanism in the class (5-bar planar parallel robot). Experimental results with achieved position accuracy of 0.012 mm as well as numerical simulation results have demonstrated the method advantage, including high accuracy results, fast calculation time, simple implementation and the feasibility when applied to the class of two-degree-of-freedom parallel mechanism in practice.

ThanhTrung Trang, Yueming Hu, Weiguang Li, ThanhLong Pham, TuanAnh Nguyen, ThiThuThuy Le

### Material Removal Rate in Electric Discharge Machining with Aluminum Tool Electrode for Ti-6Al-4V Titanium Alloy

Mechanical-physical-chemical characteristics of aluminum materials can be suitable for electrode materials, but research results with this material are still limited, and this has significantly affected its applicability in EDM. In this study, the authors studied the machining ability of aluminum electrodes in EDM to process Ti-6Al-4V. Material removal rate is the indicator used in this study. Process parameters including current (I), Gap Voltage (Vg), and pulse on time (TON) were surveyed by Taguchi method. Optimal process parameters are as follows TON = 1000 µs, Vg = 40 V and I = 40 Amp, and MRROPT = 0.0239 gm/min, and the accuracy of the result is reasonable error of 14.91%.

Nguyen Huu Phan, Vu Ngoc Pi, Shailesh Shirguppikar, M. S. Patil, Mohsen Asghari Ilani, Le Xuan Hung, T. Muthuramalingam, Tran Quoc Hung

### Mathematical Modelling of Thermoacoustic Generator Systems and Simulation Studies

In this paper, the mathematical modelling problem of thermoacoustic generator systems is investigated. An electrical circuit based method is developed by using the physical principles for each parts. Then, the modified dynamic equations as well as the compact electrical circuit are proposed to consider the controller. The proposed electrical circuit of whole of thermoacoustic generator system is employed in the mathematical modelling, which leads to simple and convenient implementation of next control designs. Finally, the effectiveness of the developed mathematical modelling is verified through simulation results.

Trong Tan Do, Duy Tung Le, Phuong Nam Dao, Minh Dinh Bui, Huy Du Dao

### Measurement Setup for Temperature-Dependent Electrical Property of ZnO-Based Thermoelectric Thin Films

An experimental setup was developed for the simultaneous measurements of the electrical resistivity and Seebeck coefficient of ZnO-based thin films in the range from room temperature up to 400 °C (673 K). The main device of measurement setup including a heater integrated with a temperature sensor so-called resistance temperature detector (RTD) made of platinum, was designed and fabricated by using CMOS technology. The temperature measurement result of integrated RTD has been calibrated and compared with the temperature conversion data of Platinum resistance provided by Intech Instruments LTD that allows ensuring the precision for the measurement of material properties. The measurement data is acquired by a Labview program. Tests of the system have been made on the samples of Al-doped ZnO films and ZnO films having hetero-layers doped with Al and Ga as n-type semiconductors. The convenience of measurement setup makes it possible the measurements with a great flexibility on sample’s geometrical dimensions.

Trinh Quang Thong, Nguyen Anh Minh, Nguyen Trong Tinh, Trieu Viet Phuong, Dao Huy Du

### Modified Q-Learning Algorithm with Lifting Method for Discrete-Time Linear Periodic Systems

This paper presents a lifting technique based modified Q-Learning algorithm for dealing with the optimal control problem of discrete-time linear periodic systems. The algorithm uses a lifting method to convert the periodic LQR problem to the time-invariant LQR problem of an improved system. The novel model-free Q-learning is proposed based on the improved system, and its convergence is proven. The proposed algorithm is implemented online to find optimal solution only using the collected data along the system trajectories. The effectiveness and convergence of the proposed strategies are validated through simulation studies.

Ngoc Trung Dang, Tien Hoang Nguyen, Phuong Nam Dao

### Multi Response Optimization of Dressing Conditions for Surface Grinding SKD11 Steel by HaiDuong Grinding Wheel Using Grey Relational Analysis in Taguchi Method

This paper presents a multi response optimization for dressing parameters for surface grinding SKD11 steel using HaiDuong grinding wheel by grey relational analysis (GRA) in the Taguchi method. The input parameters including feed rate (S), depth of rough dressing (ar), rough dressing times (nr), depth of fine dressing (af), fine dressing times (nf) and non-feeding dressing (nnon) to flatness tolerance (Fl) were investigated and optimized to obtain the smallest flatness tolerance and the highest material removal rate (MRR). The experimental results showed that optimum caculation model with dressing process for surface grinding SKD11 steel using Haiduong grinding wheel is suitable.

Tran Thi Hong, Ngo Ngoc Vu, Nguyen Huu Phan, Tran Ngoc Giang, Nguyen Thanh Tu, Le Xuan Hung, Bui Thanh Danh, Luu Anh Tung

### Multi-objective Optimization of Process Parameters During Electrical Discharge Machining of Hardened 90CrSi Steel by Applying Taguchi Technique with Grey Relational Analysis

The aim of this study is to optimize output responses as minimum surface roughness and maximum material removal rate (MRR) of Electrical Discharge Machining (EDM) process when machining hardened 90CrSi steel. Thank to this process the combination of machining parameters obtained by minimizing problems is found. The machining parameters for EDM process under consideration include concentration of powder, pulse – on - time, pulse - off - time, current, and voltage. The experiments are set up based on the L18 orthogonal array of Taguchi method, and analysis has been carried out using Grey Relational Analysis (GRA) to find the optimal set of machining parameters. ANOVA is also used to determine which parameters have the significant effects on the output responses. Finally, the experiments are performed to validate the optimal set of machining parameters. The results show that Current has the strongest influence (32,63%), and Pulse off time has the smallest effects (1,04%) on the grey grade value. The confirmation experiment and ANOVA show the reliability of the proposed model which can be considered as an effective method to predict the surface roughness and material removal rate.

Tran Thi Hong, Nguyen Manh Cuong, Nguyen Dinh Ngoc, Luu Anh Tung, Tran Ngoc Giang, Le Thu Quy, Nguyen Thanh Tu, Do Thi Tam

### Multi-objective Optimization of Surface Roughness and MRR in Surface Grinding of Hardened SKD11 Using Grey-Based Taguchi Method

The dressing plays an important role in wheel preparation in the grinding process. In this study, Grey Relational Analysis (GRA) based Taguchi method is applied to optimize the dressing parameters for minimizing the surface roughness and maximizing the material removal rate (MRR) in surface grinding of hardened SKD 11 steel. The Taguchi technique L16 is used to organize experiments that include six input parameters of the dressing process. There are two two-level parameters and four 4-level parameters including dressing feed rate, rough dressing depth, rough dressing times, fine dressing depth, fine dressing times, and non-feeding dressing. As shown in the result, the optimal dressing process for the minimum surface roughness and maximum MRR consists of 2 times of the rough dressing with a depth of 0.015 mm/stroke, a feed rate of 1.6 mm/min, 3 times non-feeding dressing, and no fine dressing was performed. Also, the dressing feed rate has the strongest impact on multiple performance characteristics (with 43.24% contribution), followed by the rough dressing depth (with 26.20% contribution). A verification experiment has demonstrated the appropriateness of the predictive model to the measurement data.

Tran Thi Hong, Do The Vinh, Tran Vinh Hung, Tran Ngoc Giang, Nguyen Thanh Tu, Le Xuan Hung, Bui Thanh Danh, Luu Anh Tung

### Multi-response Optimization in PMSEDM Process Using Taguchi-Grey Method

The optimization of input parameters on Powder Mixed Sinking Electrical Discharge Machining (PMSEDM) is critical for manufacturing industries for achieving higher productivity and product quality. In this work, a multi-target optimization of input factors for minimizing the surface roughness and maximizing the material removal rate (MRR) in PMSEDM process using Taguchi-Grey approach is presented. The five input parameters including the pulse-on-time (Ton), the pulse-off-time (Toff), the pulse current (IP), the server voltage (SV), and the powder concentration (Cp) are chosen for optimizing two responses i.e. the surface roughness and MRR. The results show that the optimal input parameters are Ton of 6 μs, Toff of 30 μs, IP of 4 A, SV of 5 V, and Cp of 6%. The optimized surface roughness obtained is 3.527 µm and the optimized MRR is 0.0724 g/min. The discovered technology mode has been applied to the real machining process and the outcome shows a considerable improvement in comparison with the default setting modes.

Tran Thi Hong, Nguyen Manh Cuong, Tran Ngoc Giang, Nguyen Anh Tuan, Le Thu Quy, Thangaraj Muthuramalingam, Nguyen Thanh Tu, Do Thi Tam

### Numerical Identification of the Mechanical Behaviour of a Fluoroelastomer (FKM) Using Nanoindentation Test

The aim of the paper is to provide a numerical model of nanoindentation tests carried out on a synthetic elastomer. Some works deal with such numerical model but on classical elastomer like silicon rubber. Our study focuses on a filled fluoro-elastomer (FKM). At first, a 2D numerical model equivalent to a Berkovich test is built. The law of behaviour used in the simulation is obtained from the results of a single traction test. Then a numerical nanoindentation test can be carried out and compared with experimental nanoindentation curves of a previous study. The relevance of the most suitable laws of behaviour is deduced.

Florent Chalon, Julie Pepin, Nathan Le Pennec, Tien-Dung Do, Stéphane Meo, Clémence Fradet, Gaelle Berton, Florian Lacroix

### On Room-Temperature Electrodeposition of Cobalt from a Deep Eutectic Solvent: A Study of Electronucleation and Growth Mechanisms

This paper demonstrates the capability of the cobalt electrodeposition from a eutectic mixture of choline chloride and urea at room temperature. Thermodynamic and kinetic aspects of cobalt electronucleation and growth mechanisms onto glassy carbon electrode were investigated. The cobalt electrodeposition, at 303 K, is dominated by progressive nucleation. The behavior of current density transients of the Co electrodeposition can be described by a model comprising the contribution due to three-dimensional nucleation and diffusion-controlled growth from metallic nuclei combined with the effect of the induction – time. The diffusion coefficient of cobalt ions in deep eutectic solvent was determined by cyclic voltammetry and best-fit parameters obtained using the proposed model. Both values were in agreement with the results published in the literature. SEM and EDS verified the presence and the nucleation type of cobalt onto glassy carbon electrode.

Thao Dao Vu Phuong, Hoang Thi Thanh Thuy, Phuong Dinh Tam, Tu Le Manh

### Optimal Design of Cab’s Isolation System for a Single-Drum Vibratory Roller

The goal of this paper is to find out the optimal parameters of cab’s isolation system to improve the ride comfort of the vibratory roller. A half-vehicle ride dynamic model of a single drum vibratory roller is established under various operating conditions. The design parameters of cab’s isolation system are optimized by the root mean square (rms) values of acceleration responses of the vertical driver’s seat (aws) and cab’s pitch angle angle (awcphi) according to the ISO 2631:1997(E) standard. A genetic algorithm (GA) and a multi-objective optimization algorithm are used for searching for the optimal design parameters of cab’s isolation systems. The study results indicate that the aws and awcphi values with GA optimal parameters reduce by 31.88% and 31.27%, respectively in comparison with the original parameters of cab’s isolation systems when the vehicle moves on the ISO class D road surface at the vehicle speed v = 5 km/h, which shows that the performance of the optimal parameters of cab’s isolation system is better than that of cab’s original isolation system in improving the ride comfort of a single drum vibratory roller at all operating conditions.

Le Van Quynh, Nguyen Tien Duy, Nguyen Van Liem, Bui Van Cuong, Le Xuan Long

### Optimization of Cutting Parameters and Nanoparticle Concentration in Hard Milling for Surface Roughness of JIS SKD61 Steel Using Linear Regression and Taguchi Method

Minimum Quantity Lubricant (MQL) technique with nanoparticles application has become one of the most effective approaches in cutting hard materials. In this present work, SiO2 particles based on cutting oil CT232 were applied in milling JIS SDK61 steel under MQL condition. The two main targets were to build a mathematical model form machining parameters to predict the surface roughness Ra of machined surface and find the optimum value of Ra. The cutting speed, feed rate, and depth of cut together with nanoparticle concentration were chosen to validate the experiments, which were designed by L27 orthogonal of the Taguchi DOE method. A fitted linear regression model was established with the coefficient of determination R-sq of 88.33%. The minimum Ra of 0.094 µm verified the predictive ability of the model. Further investigation with S/N ratio and analysis of variance (ANOVA) showed that the most significant factor was the feed rate followed by the nanoparticle concentration.

Thanh-Dat Phan, The-Vinh Do, Thanh-Long Pham, Huong-Lam Duong

### Optimization of Dressing Parameters in Surface Grinding SKD11 Tool Steel by Using Taguchi Method

Nowadays, surface grinding plays an important role in industry due to the growing demand for increasingly accurate parts with a low production cost. The efficiency of this process is affected by the process parameters such as dressing feed rate (S), rough dressing depth (ar), rough dressing times (nr), fine dressing depth (af), fine dressing times (nf), and non-feeding dressing (nnon). etc. In this paper, the optimization of dressing parameters in surface grinding SKD11 tool steel is presented. The aim of the study is to find the most appropriate value set of dressing parameters to minimize the normal cutting force (Fy). In order to solve the problem, the Taguchi method is employed. Based on an orthogonal array L16(44 × 22), sixteen experiments have been conducted. By analyzing the experimental results, an optimal solution of the optimization problem has been solved, presenting the most appropriate dressing parameters as follows: ar = 0.015 mm, nr = 1 times, af = 0 mm, nf = 0 times, nnon = 0 times, S = 1.8 m/min. The discovered technology mode has been applied into the actual machining process and the outcome shows a much better result in comparison with the default setting modes with the difference between the model values and the real values of the mean normal cutting force controlled within 3.01% of the ranges.

Tran Thi Hong, Nguyen Thanh Tu, Nguyen Anh Tuan, Tran Ngoc Giang, Nguyen Thi Quoc Dung, Le Xuan Hung, Bui Thanh Danh, Luu Anh Tung

### Optimization of PMEDM Parameters for Improving MMR in Machining 90CrSi Steel - A Taguchi Approach

To overcome the limits of the electrical discharge machining (EDM) process, the nanoscale fine powder is added to the dielectric in a new machining method called powder mixed electrical discharge machining (PMEDM). In this research, the Taguchi approach has been applied to determine the effects of PMEDM parameters such as the powder concentration, the pulse-on-time, the pulse-off-time, the pulse current, and the server voltage to material removal rate (MRR) in hardened 90CrSi steel processing. L18 orthogonal array, signal to noise (S/N) ratio, and ANOVA were employed to plan and analyze the experiment. The pulse current was determined to be the factor that had the strongest impact on MRR. Moreover, an optimal EDM condition was found to improve MRR. The powder concentration of 3.5 g/l, the pulse-on-time of 6 µs, the pulse-off-time of 30 µs, the pulse current of 12 A, and the server voltage of 5 V resulted in maximum MRR.

Tran Thi Hong, Do Thi Tam, Do The Vinh, Luu Anh Tung, Le Thu Quy, Thangaraj Muthuramalingam, Vu Ngoc Pi, Nguyen Manh Cuong

### Overshoot and Settling Time Assignment for Second-Order Systems with Time Delay

In this work, an overshoot and settling time assignment (OSA) method with filter PID is proposed for second-order system, and a control strategy is also come up with for linear time-delay systems. Then, a PID based controller design method, aimed at as small overshoot and settling time as desired, is developed for second-order systems with time delay. Some numerical simulations are given to illustrate the proposed method.

Nam Hoai Nguyen, Phuoc Doan Nguyen

### Performance Ratio Analysis Using Experimental Combining Historical Weather Data for Grid-Connected PV Systems

Along with the development of new technology, photovoltaic (PV) systems are increasingly used widely. To assess the quality of PV systems using the performance ratio (PR), to calculate this index, we need to use pyranometers with high accuracy, and of course, its price is also expensive. This article presents an alternative method for calculating the PR of a grid-connected PV system (GCPVS) based on the amount of measurement by the experiment electricity and weather history data. In addition, the article analyzes the PR for GCPVS with and without a single-axis solar tracker. The results show that the PR for GCPVS with a single-axis solar tracker is larger than the none-system. On a sunny day, the GCPVS with a single-axis tracker obtained a total in-plane solar irradiance and generated more power into the grid than the GCPVS without a single-axis tracker in the morning until early noon, and almost noon to late afternoon. The largest PR received 79.8%, an average of 66.0% and 69.2% for the GCPVS without and with a single-axis solar tracker, respectively. The analysis also shows that the PR of the GCPVS is much influenced by the temperature of the environment, which will be the premise for further studies.

Ngo Xuan Cuong, Nguyen Thi Hong, Do Anh Tuan, Do Nhu Y

### Power Control of Andronov-Hopf Oscillator Based Distributed Generation in Grid-Connected Microgrids

This paper proposes a new control method to enable simultaneous active and reactive power control of the Andronov-Hopf Oscillator Control-based VSC in grid-connected mode. An analysis based on the well-known power flow equations is implemented to determine the power tracking problem of conventional AHO. The solution of the power flow equations for given power set-points are used to change the internal parameters of the AHO to regulate the VSC power outputs. A simple control law is also used to compensate for the remaining errors caused by system uncertainties. A single AHO-controlled VSC connected to a non-stiff grid is simulated in MATLAB/Simulink to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed method exhibits a very good dynamic and steady-state performance, in comparison with conventional AHO.

Tobias Heins, Trung Tran, David Raisz, Antonello Monti

### Prediction of Cutting Force When Surface Milling Using Face Milling Tool

The aim of the study is to predict the cutting force when surface milling with a face milling tool. Based on theoretical published research on cutting force modeling, this study predicted the cutting force when milling 40Cr steel with a face milling tool. The results show that the deviation of predicted cutting force was approximately 15.7% in comparison with the test, and about 9.9% compared to the predicted value using regression model, while the cutting force predicted using regression model deviated 9.6% from the test results. Also, development directions for further studies are suggested.

Nguyen Van Thien, Do Duc Trung, Vilaivanh Xaixavang, Tran Thi Hong, Nguyen Thanh Tu, Tran Ngoc Giang, Le Xuan Hung

### Research Method for Calculating Additional Power Losses, Considering the Asymmetric Loads in the Low-Voltage Power Supply System Vietnam

The efficiency of the use of electric energy is determined by the creation of consumption conditions under which the required quality of electric energy and a minimum of losses are ensured. The urgency of improving the quality and reducing losses of electric energy is especially growing in the power supply system with voltage up to 1 kV, due to the fact that he power supply system in the Vietnam, such a mode of operation as asymmetrical is widespread.This is due to the distribution of electricity consumers in three-phase power supply systems, the symmetric multiphase design of which is either impossible or impractical for technical and economic reasons. Voltage asymmetry is characterized by the presence of reverse or zero sequence voltages in a three-phase power supply system, significantly smaller in magnitude of the corresponding voltage components of the forward (main) sequence. In the presence of reverse and zero sequence currents, the total currents in individual phases of the elements in the low voltage power supply system increase, which leads to an increase in active power losses and may be unacceptable from the point of view of heating and operating costs. The paper is devoted to methods of calculating additional power losses in the low voltage power supply system in Vietnam. Through coefficient $$k_{add}$$ k add , with any low voltage power supply system and with any operating mode can accurately calculate the amount of additional power loss caused by asymmetric loads.

Pham Trung Son

### Research to Improve the Quality Control for Drive System Tracking Electromechanical Takes into Account Nonlinear Undetermined Application in Industrial Production

In this paper, author present a synthesis method adaptive sliding mode controller for drive systems tracking electric mechanisms working slow speed using synchronous AC motors is used in the industrial and military taking into account the nonlinear undetermined and the change parameters of the model. Building adaptive law to determine the parameters uncertain and build the sliding mode observer to estimate the torques: load torque, friction torque and disturb. The controller is proposed to improve the quality of electric mechanisms systems when the sticking to the components listed above nonlinear uncertain. The calculation and design of this controller, the controller on the basis of speed synchronous AC motors. The research results will be the basis for the establishment of control algorithms, system design electric drives in the industry and military.

Tran Duc Chuyen, Do Quang Hiep, Dao Huy Du

### Role of Electrolyte Media in the Exfoliation of MoS2 Nanosheets by Electrolysis Plasma-Induced Method

Liquid phase exfoliation of two-dimensional materials by the plasma-induced method is one of the favorable and low-cost methods for fast preparation of molybdenum disulfide nanosheets. In this report, we study the role of electrolytes media in the plasma-induced process with the comparison of exfoliation of MoS2 in both base and acid electrolyte. By using NaOH and H2SO4 electrolyte in the electrolysis plasma system, bulk material of MoS2 was exfoliated to MoS2 nanosheets. The high crystalline of a few MoS2 nanosheets with hundred nanometers lateral size was obtained. Interestingly, the high-resolution transmission electron microscopy exhibited that MoS2 nanosheets obtained by using acidic electrolyte show a slight increase of interlayer spacing. The thermal expansion in the explosion of plasma and the synergic of different kinds of ions play an important role in the exfoliation of a few MoS2 nanosheets. These results reveal the important understanding of the intercalation of electrolyte ion into the exfoliation of MoS2 nanosheets in the plasma-induced process.

Van-Truong Nguyen, Tien-Dat Hoang, Nguyen Thi Kim Ngan, Pham Minh Tan, Dang Van Thanh

### Simulated Annealing Algorithm for Modeling Large Deflection of Flexible Links in Complaint Mechanisms

Modeling large deflection of flexible link using Pseudo-Rigid-Body (PRB) models plays an important role in compliant mechanisms since these models are helpful for analyzing and synthesizing kinematics and dynamics of compliant mechanisms. However, one of major challenges is how to improve of the model for modeling large deflection of compliant mechanisms. This paper presents a methodology for determining the optimal characteristic radius parameters and stiffness coefficients of PRB model for modeling large deflection of flexible links based on a simulated annealing algorithm. The new objective function is built by the evaluation of the difference between the tip point and the slope angle of the flexible link and the model. The results demonstrate that the optimal parameters are used in the proposed model to increase the accuracy of the PRB model.

Nguyen Thi Thanh Nga, Nguyen Thi Bich Ngoc, Nguyen Van-Sy, Nguyen Dinh-Ngoc, Nguyen Quang-Hung, Hoang Tien Dat

### Study on Thermal Convective Gas Gyroscope Based on Corona Discharge Ion Wind and Coriolis Effect

In this paper, we report on a gas gyroscope whose working principle is based on elec-tro-hydrodynamic flow generated by applying high voltage corona discharge, Coriolis acceleration and thermoresistive effects of sensing elements. Firstly, ionized air flow is created by applying high voltage between pin-ring electrodes as discharge-reference electrodes. When the sensor rotates, the ion wind is deflected because of Coriolis effect and four symmetric hot wires are used to recognize the direction change of ion wind. The simulation result confirms the deflection of air flow due to Coriolis force and the asymmetric thermal distribution of hot wires. The experiment result shows that the angular rate can be detected with a sensitivity of 4.7 µV/o/s.

Hang Nguyen Thu, Ngoc Tran Van, Cuong Nguyen Nhu, Van Thanh Dau, An Nguyen Ngoc, Trinh Chu Duc, Tung Thanh Bui

### Studying Electron Transport Coefficients in C2H4-SiH4 Mixtures Using Bolsig+ Program

For the first time the electron transport coefficients in C2H4-SiH4 mixtures were calculated by using the Bolsig+ freeware for the E/N (ratio of the electric field E to the neutral number density N) range of 0.1–1000 Td (Townsend). The electron collision cross section sets for C2H4 and SiH4 molecules were chosen and modified to ensure reliability before calculation. Therefore, the electron transport coefficients in C2H4-SiH4 mixtures are useful for plasma modeling.

Pham Xuan Hien, Tran Thanh Son, Do Anh Tuan

### Synthesis of Automatic Motion Control Systems of an AUV Based on Fuzzy Logic Methods with Neural Network Setting of Parameters

The article deals with the problem of controlling the stabilization of the depth of an autonomous underwater vehicle with a search type. The main results in this area were obtained for torpedo-shaped underwater vehicles, the dynamics of which significantly differs from the dynamics of the object under study. An algorithm is presented; methods of fuzzy logic are used for neural network adjustment of control parameters so that the result of the operation of a fuzzy controller is reproduced. This algorithm can be applied to playback and other regulators, which makes it a universal tool for building automatic control systems. The results of modeling the controlled movement of an underwater vehicle in the vertical plane are presented, showing the highly efficient functioning of the adaptive neuro-fuzzy control in comparison with the proportional-differential controller.

Van Tuan Pham, Thi Ha Nguyen

### Taguchi-DEAR Based MCDM Approach on Machining Titanium Alloy in AWJM Process

Abrasive water jet machining is an effective process for machining various engineering materials. This paper investigated the effects of process parameters on depth of cut in abrasive water jet cutting of titanium alloy. Four different process parameters were undertaken for this study; water pressure, nozzle traverse speed, abrasive mass flow rate and standoff distance. In the present study Taguchi- DEAR multiple response optimization methodology has been utilized to compute optimal process factors on machining titanium alloy using AWJM process. The optimal process parameters of AWJM process has been found as 1000 bar (P), 600 mg/min (QA), 3.5 mm (SOD) and 475 mm/min (F) respectively among the chosen parameters and their ranges. It has been found that the process parameters of stand-off-distance have highest impact on performance measures.

T. Muthuramalingam, Vu Ngoc Pi, Ammar H. Elsheikh

### The Characterization of Machined Damage of CFRP Composite: Comparison of 2D and 3D Surface Roughness Performance

Machining damage generated during a trimming process of CFRP composite may reduce the integrity of machined surface, hence, this can impact highly on the mechanical properties of composite structures in services. For this reason, the damage caused in the machined surface should be quantified and correlated to mechanical properties of composite structures. In this study, the machining damage generated during the trimming of CFRP composite specimens will be characterized using roughness criteria including both 2D and 3D. These criteria will be correlated to compressive strength. The results reveal that 3D roughness criterion seems to be better than 2D one when both are utilized.

Nguyen Dinh Ngoc, Duong Pham Tuong Minh, Nguyen Van Sy, Luong Viet Dung, Nguyen Thi Thanh Nga, Nguyen Dang Hao, Hoang Tien Dat

### The Dimensional Synthesis of the Four-Bar Mechanism with a Symbiotic Organisms Search Algorithm

The dimensional synthesis of the four-bar mechanism has been solved by using many meta-heuristic approaches such as genetic algorithm (GA), differential evolution (DE), and/or particle swarm optimization (PSO) However, the performance of a symbiotic organisms search (SOS) for the dimensional synthesis of the four-bar mechanism has not been investigated so far. Thus, this study aims to investigate the applicability of SOS in the optimal dimensional design of a four-bar mechanism by comparing the results gotten by SOS with those of DE, GA, and PSO. The results of SOS for the dimensional synthesis of the four-bar mechanism show that the SOS has a good exploitation ability for a fast converge rate but it has a limited exploration capability to find accurate solutions.

Sy Nguyen-Van, Ngoc Nguyen-Dinh, P. T. M. Duong, Nguyen Quang Hung, Thi Thanh Nga Nguyen

### The Effect of Bonnet Skin and Bonnet Reinforcement Thickness on Pedestrian Head Injuries in Collisions

Nowadays, automotive manufacturers are more and more paying attention to protecting pedestrians besides occupant’s safety, due to thousands of pedestrians are killed or maimed seriously in automotive-related accidents annually as well as the increasingly strict requirements of the automotive markets. Previous research has shown that head and face injuries in car-pedestrian accidents account for 60% of all pedestrian fatal injuries, whereas 17.3% of head injuries were due to the bonnet. There have been many design solutions for the bonnet to protect the pedestrian’s head in the collision, including the solution to reduce bonnet stiffness and bonnet skin thickness. In this study, the effect of bonnet skin and bonnet reinforcement thickness on pedestrian head injuries in collisions will be analyzed by using simulations of head form to bonnet top test with some value of bonnet skin and bonnet reinforcement thickness. The results of this study will be useful in design bonnet structure for pedestrian safety in collisions.

Van-Luc Ngo, Minh Khong

### The Effect of the Wheel Rotation Angle on the Braking Efficiency of the Tractor Semi-trailer on the Wet Roundabout Route

The paper presents how to set up a 3D dynamic model to study the effect of the wheel rotation angle on the braking efficiency of the tractor semi-trailer on the wet roundabout route. The method of structural separation of a multi-object system was used to set up a 3D dynamic model, and the method of the Newton-Euler equation system was used to establish the dynamic equation system of the tractor semi-trailer. The Matlab-Simulink software was used to examine the effect of the wheel rotation angle on the braking efficiency of the tractor semi-trailer on the wet roundabout route. The results showed that, when the wheel rotation angle was δ = 3o, the longitudinal acceleration of the tractor and semi-trailer was about 3.2[m/s2], the deviation angle between the tractor and the semi-trailer ψK = 9o, the tractor semi-trailer works stably and safely; when the rotation angle wheel was δ = 5o, the longitudinal acceleration of the tractor was about 3.8[m/s2], the longitudinal acceleration of the semi-trailer was about 3.2[m/s2], the deviation angle between the tractor and the semi-trailer was ψK = 70o, the tractor semi-trailer was oversteered with an unstable movement.

Nguyen Thanh Tung, Vo Van Huong

### The Effect of Welding Speed on the Mechanical Properties of the FSW Cu/Al

This study was carried out to join pure copper C1100 plate and aluminum 1050 plate by friction stir welding. The effect of the welding speed on the macrostructure and mechanical properties of the joints was investigated. At various welding speeds, the tunnel defects seemed to be inevitable. However, at high speed, the tunnel size is small, and the size is increased with the reduction of the tool offset. The tensile strength reached the highest value at a welding regime with the tool offset around 2.5 mm, and the fractures took placed at the interface. The strength bonding between copper and aluminum could be obtained at least 80% of the base aluminum 1050.

Tran Hung Tra, Quach Hoai Nam, Phi Cong Thuyen, Duong Dinh Hao, Truong Thanh Chung, Pham Trong Hop, Ho Huu Huy, Vu Lai Hoang, Chu Hoang Duc Anh

### The New Method to Control Twin Rotor MIMO System (TRMS)

The algebra theory was developed by the group of authors in the 1990s and has had a great deal of application in various fields, such as information technology, image processing, control and automation. This paper presents the application of hedge algebras based on fuzzy logic to control TRMS, including the construction of the hedge-algebras-argument system; building the hedge-algebras-based controller (HAC) structure for nonlinear MIMO system; modeling, simulating the control TRMS. The results generated by the HAC are modelling and simulation in matlab-simulink demonstrating the superiority and feasibility of the proposed controller.

Lai Khac Lai, Trinh Thuy Ha, Vu Nhu Lan, Nguyen Tien Duy

### Theoretical and Experimental Study of Sound Transmission Loss Across Finite Clamped Composite Sandwich Plates

Theoretical and experimental studies of sound transmission loss across a clamped double-laminated composite plate filled with poroelastic material are formulated. Biot’s theory is employed to describe wave propagation in elastic porous media. The two face composite plates are modeled as classical thin plates. By using the modal superposition theory, a double series solution for the sound transmission loss of the structure is obtained with the help of the Galerkin method. The analytical model is validated against previous experimental results of the diffused sound wave under normal incidence. The numerical results were compared with experimental results across three structural groups (the core density, the skin thickness and the core dimension). Thereby, the role of the component material is assessed to the sound insulation capacity of the composite sandwich plate.

Tran Ich Thinh, Pham Ngoc Thanh

### Tool Wear Rate Analysis of Uncoated and AlCrNi Coated Aluminum Electrode in EDM for Ti-6Al-4 V Titanium Alloy

Tool wear rate (TWR) in EDM has a direct effect on machining accuracy and production costs. Many new electrode materials have been introduced to improve TWR, and electrodes sprayed with refractory alloys are said to be new research directions with its prospects as well. In this study, the research team compared TWR of coated and uncoated electrodes in EDM for Ti-6AL-4 V titanium alloy. The basic electrode material is aluminum, and the coating material on the electrode surface is AlCrNi. Process parameters including current (I), gap volt (Vg), pulse on time (TON) were surveyed via Taguchi method. The results showed that TON and I are strongly influencing the TWR of both electrodes. The TWR of Al electrode is approximately 24% larger than that of coated Al electrode.

Nguyen Huu Phan, Vu Ngoc Pi, Nguyen Quoc Tuan, Shailesh Shirguppikar, M. S. Patil, Mohsen Asghari Ilani, Le Xuan Hung, T. Muthuramalingam, Tran Quoc Hung

### Tracking Control of Directed Acyclic Formation via Target Point Localization

This paper studies a leader-follower formation tracking problem where the leaders are moving with an unknown bounded velocity in the $$d$$ d -dimensional space. Based on leaders’ positions, each agent determines and tracks the desired moving position, which is called the target point. The characteristics of the proposed control laws are then examined in details. Simulations are also provided to support the theoretical analysis.

Dung Van Vu, Trung Thanh Cao, Minh Hoang Trinh, Hyo-Sung Ahn

### Tracking Control of Rostock Delta Parallel Robot Based on the Dynamic Model

Parallel robots are being applied popular in industry. They usually have many closed-loop kinematic structures, therefore their movement equations have the form of redundant coordinates and are complex. In most cases, parameters of dynamic model of the parallel robots required to be known exactly for control problem using the control laws such as PD, PID, CTC. This study is going to see in which the conditions of the Rostock Delta parallel robot should be used well with the PD control law. The movement equations of Rostock Delta robot in the form of differential equation system with redundant generalized coordinates is used to establish the PD control law. The stableness of the control law is also proved. Tracking control of a specific Rostock Delta robot is then simulated to see whether the PD control law could be used effectively or not in the cases of with and without the error of robot and noise.

Vu Le Huy, Le Thi Huyen Linh, Nguyen Dinh Dzung

### Trajectory Tracking Control of a Caterpillar Vehicle

This paper presents the experimental results of the tracking control of a Caterpillar Vehicle. The proposed scheme involves three steps: 1, building a model of a Caterpillar Vehicle system with two wheeled vehicle; 2, apply back stepping control method for trajectory tracking of the Caterpillar Vehicle; 3, The model reference adaptive control (MRAC) technique is used to design a controller that ensure the stability of the system. The MRAC technique is used to design a controller that is able to address the effects caused by changes in the desired trajectory reference. The MRAC controller is first evaluated using computer simulations which show that the controller is able to effectively respond to changes in the desired trajectory. The simulation results compare the quality of the two controllers using the back stepping control method and MRAC when the desired trajectory is Straight or curved line. Based on the comparison results, MRAC is proposed to track the desired trajectory.

Do Trung Hai, Bui Thi Hai Linh, Tran Ngoc Anh

### Truss Optimization Under Frequency Constraints by Using a Combined Differential Evolution and Jaya Algorithm

A combined differential evolution (DE) and Jaya algorithm, named CDJ, for size and shape truss optimization under frequency constraints is suggested in this paper. In CDJ, a combined operator of the original DE and Jaya are used to achieve both the global and local searching abilities. Then, the elitist selection technique is used in the selection stage. As a result, the CDJ can generate good solutions with a small computational effort in comparison with two original methods and some other optimization algorithms in the literature. To validate its feasibility, two numerical examples of shape and size optimization and size optimization are performed.

Sy Nguyen-Van, Thi Thanh Nga Nguyen, Ngoc Nguyen-Dinh, Qui X. Lieu

### Web Tension Observer Based Control for Single-Span Roll to Roll Systems

Roll-to-roll (R2R) systems prove great potential for high-throughput and cost-effective production of flexible electronics, including solar cells, wearable sensors, and so on. Actually, most of design methods for tension controller of web transport system (such as paper, plastic film, etc.) require state variables as feedback. These variables can be measured directly using the sensors. However, the complex systems that have many states will require many sensors which makes the control system bulky and expensive. Moreover, direct measurements are difficult or tend to be inaccurate in many systems. In R2R systems, precise regulation of span tension is critical to ensure product quality. Elevated tension causes web fracture during operation; depressed or highly variable tension leads to irregular and unacceptable spool. The approach in this paper is to model the state observer with only a small number of sensors. Then, we will propose a method to build tension controller based on backstepping controller using the tension observer. Simulation has shown that the proposed controllers with tension observer well-perform against the inertia disturbances.

Thi Ly Tong, Minh Duc Duong, Danh Huy Nguyen, Tung Lam Nguyen

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