Journal of Technology and Social Science (JTSS, J. Tech. Soc. Sci.)
An international open-access peer-reviewed journal
TABLE OF CONTENTS
Promising Magnesium Alloys for Mobility and Portability
Dongwei Shu, Iram R Ahmad, Jing Xiao
Journal of Technology and Social Science, Vol.2, No.2, pp.1-6, 2018.
Abstract: Magnesium alloys being the lightest of all metals offer great potential to achieve weight reduction by replacing the most commonly used materials, i.e. steel, aluminium and plastics. Limited data available for high strain rate deformation of magnesium alloys combined with an insufficient understanding of the underlying deformation mechanisms adds to the reservations for their use as structural materials. Limited data is available for high strain rate deformation of magnesium alloy and its nanocomposites, which makes it difficult for widespread usage of these lightweight materials. For widespread usage of magnesium alloys, their dynamic behaviour must be determined to assess their performance during a crash event. In the present work, an experimental and numerical study followed by the microstructural analysis has been carried out to investigate the dynamic behaviour of as-cast AZ91D and wrought AZ31B magnesium alloys. These alloys have been tested at strain rates in the range between 10-4s-1 and 4x103s-1 and at temperatures between -30oC and 200oC under compression and under tension between 10-4s-1 and 1500s-1 strain rates and at 25oC and at 250oC temperatures. Increasing stresses, larger strains and higher energy absorption are observed with increasing strain rate in both alloys under compression as well as in tension. Temperature has little effect on the mechanical behaviour of these alloys at dynamic strain rates. It has been found that the addition of stiffer and stronger second-phase reinforcements can enhance strength and ductility of magnesium alloys. Micro-sized reinforcements are effective in enhancing stiffness and strength but accompanied by an obvious decrease in ductility. In the present work, the compressive mechanical response of magnesium alloy AZ31B, AZ31B/0.5%SiC and AZ31B/1.0%SiC to quasi-static and dynamic loading over a wide range of temperature is investigated. The addition of silicon carbide nanoparticles can enhance the strength of the base alloy, while it slightly decreases the ductility of the material. It doesnüft apply to all strain-rate and temperature conditions that higher volume fraction of nanoparticles results in higher strength.
Maritime Autonomous Surface Vessels: A Review of RobotX Challengeüfs Works
Xie Ming and Sai Sahith Velamala
Journal of Technology and Social Science, Vol.2, No.2, pp.7-14, 2018.
Abstract: The Maritime RobotX Challenge was created as a platform which showcases the advancements made in autonomous vehicle technology and to promote further research and development in the field. The competition requires participating teams to modify a 16üf WAM-V USV in order to complete the challenge objectives including navigation control, obstacle avoidance, station keeping, code scanning, underwater symbol/shape identification and object delivery. This paper details the various hardware additions, control algorithms and software used by the participating teams on their competing vehicle in order to achieve maximum possible accuracy and efficiency of task completion.
Linearity Enhancement Algorithms of Multi-bit âóâ░ DA Converter –DWA, Self-Calibration and Their Combination
Jun-ya Kojima, Nene Kushita, Masahiro Murakami and Haruo Kobayashi
Journal of Technology and Social Science, Vol.2, No.2, pp.15-28, 2018.
Abstract: This paper presents several linearity improvement algorithms for multi-bit âóâ░ digital-to-analog converters (DACs), utilizing digital signal processing (DSP) techniques. The âóâ░ DACs are used for electronic measurement and automatic test equipment as well as audio systems, for their easy implementation of high resolution and high linearity. However, their multi-bit configuration (which consists of a digital âóâ░ modulator and a multi-bit DAC) causes the DAC non-linearity due to characteristics mismatches among multiple unit cells, even though they can be implemented with small hardware and power. Therefore, we investigate several algorithms, Data-Weighted Averaging (DWA) algorithms and self-calibration as well as their combination, which improve the overall âóâ░ DAC linearity. We have simulated a ternary (three values: positive, zero, negative) DAC as well as a binary (two values: positive, zero) DAC. From these simulations, we have found that for the low-pass (LP) signal band, DWA type I is effective in case of both ternary and binary DACs; for the high-pass (HP) signal band, DWA type I is effective in the case of the ternary, whereas DWA type II is effective in the case of the binary. The proposed algorithms use DSP techniques and hence they are easy to implement.
Remote Learning Support System Using a Mobile Robot Operated by Eye-gaze Input for Long Time School Non-attendance Students
Yeon Kyong, Satoru Shibata, Tomonori Karita and Shenglin Mu
Journal of Technology and Social Science, Vol.2, No.2, pp.29-35, 2018.
Abstract: It is difficult for children or students under hospital care by the reasons of severe disease or injury to attend school classes. In this paper, we propose a system which enables them to join classes and communicate with friends and teachers by controlling an alter ego robot from a distant place. As the interface between the children or students and the avatar robot, we pay attention to eye movement because its function remains to the last. Using eye-gaze input, we construct a system to acquire environmental information by controlling the orientation of the robot and camera attached at the robot. The robot used in this system sends images acquired from the camera to the monitor in front of the operator in order for the operator to get environmental information of the surrounding area. Then the operator confirms the target inside the image by the control of the orientation of the camera and the robot.
DC Micro-Grid Contactless Power Supply System with Active Load Detecting Control Method
Song Xu, Seiji Hashimoto and Wei Jiang
Journal of Technology and Social Science, Vol.2, No.2, pp.36-44, 2018.
Abstract: DC micro-grid is gaining an increasing attention in the field of power organization because of its high efficiency and intelligence in power organizing and using abilities. In this paper, a contactless power supply system for the mobile active load in the DC micro-grid with resonant network has been designed and analyzed. Moreover, for the energy saving purpose, the load detection function has been added to the transfer system. The theoretical analysis of the power transfer system and the resonant network is proposed. The simulation has been carried out in MATLAB/SIMULINK to test the control method. The experiment platform is built with a dsPIC controller, and then experiments are carried out to confirm the theoretical analysis and to verify the control efficiency of the load detecting control method.
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