Taiwan Association of Engineering and Technology Innovation: E-Journals
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A New Efficient Topology of Single-Phase Five-level Inverter for PV System
Get PDFThis paper presents the design, simulation, and implementation of a new single-phase five-level inverter, for photovoltaic systems, with a reduced number of power switches and fewer gate-drivers power supply. This multilevel inverter consists of a high step-up DC-DC converter, a switched-capacitor converter, and a full bridge converter. The proposed topology is used to deliver optimal AC voltage and current with fewer harmonics to the loads by controlling the high step-up DC-DC converter with a small duty cycle. A prototype of a 200W rated power feeding an inductive load from solar panels is tested by simulation and experiment. A maximum power point tracking method and a pulse width modulation technique are presented and evaluated under normalized criteria for voltage, frequency, and total harmonics distortion (THD). The experimental results show that the proposed multi-level inverter is an efficient converter to supply power energy from solar panels to industrial machines such as single phase induction motors
On the Mechanism Design of an Innovative Elliptical Exerciser with Quick-Return Effect
Get PDFThe objective of this study is to propose and investigate an innovative elliptical exerciser with quick-return effect that mimics the timing of the foot trajectory while jogging. At first, the innovative mechanism of the elliptical exerciser with quick-return effect is proposed. The structure and function of the proposed design are introduced. Then, the mechanism is analysed kinematically using the vector-loop method and motion geometry of the mechanism. An illustration is presented for explaining the design procedure of the proposed innovative design. Finally, the pedal trajectory of the innovative elliptical exerciser is simulated. The simulation results validate that the motion of pedal trajectory on the striding travel is faster than that on the supporting travel. Because of this quick-return effect, the timing of the pedal trajectory meets the principles of ergonomics and prevents the user suffering from muscle sore, pain or even injury
Comparative Analysis of Performance of R600a and R510a Refrigerants in a Retrofitted Refrigerating System
Get PDFHydrocarbons, in the environmentally friendly group have drawn much attention of scientists and researchers for application as refrigerants. In this work, the performance of two eco-friendly hydrocarbon refrigerants (R510A and R600a) in a retrofitted vapour compression refrigeration system was investigated experimentally and compared with the baseline hydro fluorocarbon refrigerant (R134a). Thermocouples and pressure gauges were fitted at the inlet and outlet of the compressor, condenser, and evaporator to measure the temperature and pressure of the refrigerant at various stages of the refrigeration cycle. The results obtained showed that the coefficient of performance (COP) of the system using the two hydrocarbon refrigerants was higher than the coefficient of performance (COP) obtained using R134a as a working fluid. Generally, the two hydrocarbon refrigerants performed better than R134a, but R510A gave the best overall performance in that it exhibited the lowest discharge pressure of 0.656MN/m2and the highest refrigerating effect of 253.29kJ/kg
Investigation of Peel Resistance of Adhesives Materials: A Review
Get PDFDifferent adhesives are used for joining the different types of materials. The different types of peel tests available for investigating the adhesive strength are 90º, 135º, 180º and T-peel test. This paper reviews the different peel tests available as well influence of other factors for determining of peel resistance between two materials. The investigation of adhesive strength helps to select a proper adhesive material for joining of two different materials. The paper briefs the effect of peel angle, different types of peel tests such as 90º and T-peel test, temperature, moisture, thickness, the rate of change of peeling rate on peel strength
Innovation for Education on Internet of Things
Get PDFThe Internet of Things (IoT) and related objects are becoming more prevalent around the world with exponential growth for the next fifteen years. This evolution implies innovation in many fields of technology, whose core is in microelectronics. Indeed, IoT deals with all societal applications such as health, the environment, transport, energy and communications. Thus, connected objects involve many technological components: sensors and actuators, signal processing circuits, data transmission circuits and systems, energy recovery systems, which directly depend on the performance of microelectronics. To create new connected objects, innovation is the main driver. Innovation results from the combination of a multidisciplinary approach, links between disciplines and the necessary know-how of engineers and technicians. This paper deals with the orientation of pedagogy towards these objectives through the development of dedicated and innovative platforms in microelectronics. These platforms are developed by the French National Microelectronics Education Network (CNFM). After presenting the context of IoT and the evolution of microelectronics technologies, this article highlights the main components of connected objects applied to many societal applications. Each component of the objects requires specific microelectronic devices or circuits. Innovation appears in the nature of platforms, the multidisciplinary approach of training, the permanent links between disciplines, and the adaptation to new educational tools, mainly online. The results of the training on innovative platforms are presented and discussed
Message-Efficient Route Planning Based on Comprehensive Real-time Traffic Map in VANETs
Get PDFTraffic congestion has become one of the major society issues in many urban areas around the world. It greatly increases the commuting time and fuel consumption. Researchers have proposed many solutions in different aspects to alleviate this issue. In recent years, many works adopt Vehicular Ad Hoc Networks (VANETs) to relieve the problem. Vehicles with communication ability can receive traffic information from infrastructures or other vehicles. Furthermore, drivers can select its driving path by avoiding congestion areas based on the real-time information. However, to speed up the procedures of information collections, many existing works suggest proactive messages to acquire traffic information from other vehicles, which incurs heavy communication overheads. In this work, we propose a real-time traffic collection mechanism, which adopt both proactive and passive schemes. Vehicles passively collect traffic information in most of the time, and proactively broadcast the traffic data only in certain situations in order to speed up urgent information spreading. Thus, vehicles can obtain real-time traffic information in a low-cost way. In addition, we propose a routing planning scheme, which considers travel time, reliability, expected traffic flow as well as other factors, to select reliable and fast routes for vehicles. The simulation results show that, comparing with previous works, the proposed schemes can find better driving paths for vehicles with lower communication cost
Development of a Dryer with a Heat Exchanger to Recover Energy for Drying Agricultural Produce
Get PDFThe purpose of this study was to investigate the effect of a heat recovery by guiding the exhaust air through a heat exchanger in a hot air dryer. The temperature of inlet air could be increased by the developed heat recovery device to achieve energy saving. Experimental results indicated that the heat recovery device could increase the inlet fresh temperature 11℃, the effectiveness ratio of the heat exchanger was up to 70-80%, and heating efficiency of the heater was 50% through the analysis of inlet and outlet temperature, airflow rate as well as fuel consumption of the heater. In addition, the maximum temperature difference in the drying chamber was in the range of 0.6-1.2℃, indicating that the airflow in the drying was uniform, thus the uniform quality of agricultural produce could be obtained. In order to analyse the optimum operation conditions, the effect of fan speed on the temperature and airflow distribution was investigated in the drying system. The results showed that the optimum fan speed should be faster during start-up period and lower during a steady stage
Fresh Properties and Strength Development of Cement Mortar Using Nitrite-based Accelerator and Chemical Admixtures
Get PDFA nonfreezing agent prevents initial frost damage by simplified curing and also promotes early strength development. In general, a nitrite-based accelerator is used as the main component of this nonfreezing agent. When a large proportion of a conventional accelerator is used, the slump loss increases because the setting and hardening processes are strongly enhanced. In addition, these conventional accelerators may not be sufficiently effective at temperatures of -10 °C or less. Therefore, the fresh properties and strength development of cement mortars when using a nitrite-based accelerator and chemical admixtures in a low-temperature environment are examined. The objective is to develop a high-performance nonfreezing agent. This paper presents the contributions of the nitrite-based accelerator and two types of high-range water-reducing agents, used in combination. From the investigation, it was confirmed that the change in the mortar flow can be suppressed by combining two types of high-range water-reducing agents with a nitrite-based accelerator, even after the passage of 60 min after mixing. Furthermore, the mix was found to contribute to not only the initial strength but also toward maintaining the good strength for a longer time
Piglets Comfort with Hot Water by Biogas Combustion under Controllable Ventilation
Get PDFThe purpose of this study is to develop a hot-water heating system for pig farms which use biogas as the energy source while the air quality is regulated using an inverter-controlled fan. The biogas is a by-product from the 3-stage wastewater treatment process in regular pig farms. The biogas is burned for hot water which is circulated to warm piglet compartments with regulated, forced ventilation. The hot water is connected to a heat exchanger and hot air is hence blown into the pigsty. To maintain the pigsty at a comfort atmosphere, ventilation is regulated using an inverter-controlled fan. The mechanical ventilation is to be optimized as a compromise between indoor air quality and ventilation rate. The temperature uniformity and air quality in the pigsty is to be secured for comfortability. Experimental results show that hot water circulating at 0.043 m3/min and 60°C could keep the pigsty at 28°C for a stocking density of 1.77 pig/m2. Forced ventilation of 1.7 ACH (air change rate per hour) at 28°C could keep the pigsty comfort in terms of indoor temperature, relative humidity, and carbon-dioxide concentration
International Flipped Class for Chinese Honors Bachelor Students in the Frame of Multidisciplinary Fields: Reliability and Microelectronics
Get PDFThis paper reports an innovative pedagogic experience performed at South-East University (SEU) with electrical engineering Bachelor honors students (computer science, mechanics, and electronics). The purpose was to develop their motivation and to make them aware of the strategic importance of two aspects of electronic engineering i.e. integrated technologies and reliability assessment of devices and systems. The pedagogical approach was based on a flipped class and learning by project that consisted to involve the students in the two topics. After several lectures on the fundamentals of microelectronics and reliability of electronics components performed by foreign professors, twelve groups of five students were built. Each group had to develop one topic, chosen for its strategic importance. Thus, from a given set of main literature references, the students prepared during three days a twelve pages report and an oral presentation, both in English language. Results were generally very good. Most of the students succeeded in addressing issues that were completely new for them. They clearly built by themselves the skills allowing understanding of all the important aspects of the topics they had to approach. This paper gives details on the organization, the content and the final evaluation