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A Comprehensive Study on Safety of New Energy Vehicles
Full text linkNew energy vehicles (NEVs) have become a fundamental part of transportation system. Performance of an NEV is hugely determined by batteries, motors, and embedded electric control units. In this paper, a comprehensive study that covers all these key components is presented. Mechanisms and characterizations of failures are given in detail. On top of these, algorithms for fault diagnosis are established based on big data of real-world NEVs with joint considerations of design flaws, usage behaviors, and environmental conditions. In this way, multiple types of faults can be detected ahead of time to avoid accident. Proposed methods have been verified by real-world operational data, indicating effectiveness while providing insights for NEV design optimization
Parametric Modelling of Pedal Pressing Activities During Road Traffic Delay
Full text linkAbstract: Traffic congestion in big cities in Malaysia has become a common scenario among the communities. The journey between homes to working place twice a day at considerable distances is no longer a strange situation. Being in traffic for hours in a sitting position requires recurrent tasks of manual pressing the pedal and brake excessively and if they are done without the correct sitting posture, it may trigger fatigue faster, particularly for the leg and back of the driver. In the long term, it will negatively affect the health of the driver, particularly in the form of physical, psychological, and emotional. Therefore, this paper is trying to investigate the recurrent brake pedal pressings as well as the leg postures while driving in traffic jam. The research is started with the experimental setup and data acquisition on brake pedal pressing as well as leg posture followed by the modelling and analysis of the obtained data using particle swarm optimization (PSO) modelling technique. The validation step was then executed to verify the model derived using open loop and closed loop performance analysis. The results show that the pedal pressing force of leg posture can be closely represented using 2ndorder transfer function and mimics the actual pedal pressing pattern during road traffic delay
Electrical Transport and Current Conduction Mechanisms in ZnO/Si Heterojunction Diode
Full text linkAbstract: The objective of this research is the relevant equations of electrical transport inside a junction device based on metallic oxides like zinc oxides retained on silicon substrate by spray pyrolysis process. Many characteristics, such as the heterojunction diode\u27s non-ideal conduct, electronic conduction of electrons and gaps in the conduction and valence bands, charge carriers caught by trap centers, hopping conduction, and tunnel effect, are used in various conduction processes at electronic junctions. Poole-Frenkel (PF) emission, Schottky emissions, and trap aided tunneling are some of the other conduction mechanisms examined inside forward/reverse bias for ZnO/Si heterojunctions (TAT). This article also confirms, addresses, and elucidates the effect of temperature on the I-V properties of ZnO/Si.
https://ecee.colorado.edu/~bart/book/book/chapter3/ch3_9.ht
Analyze and Optimize the Welding Parameters of the Process by Pulsed Tubular Wire (FCAW - Flux Cored Arc Welding) Based on the Geometry of the Weld Beads Resulting from each Test
Full text linkAbstract: This study aimed to analyze and optimize deposition welding parameters using a pulsed tubular wire process (FCAW - Flux Cored Arc Welding), where the influence variables adopted were the average current, the pulsation frequency, the welding speed and the contact-tip-workpiece distance, with each variable being tested at three different levels. The geometric characteristics evaluated, that is, the response variables, are width, reinforcement, penetration, reinforcement area, penetration area and dilution. The geometric characteristics evaluated, that is, the response variables, are the width, the reinforcement, the penetration, the reinforcement area, the penetration area, the contact-tip-workpiece distance and the dilution. In order to achieve the proposed objective, statistical techniques were used as analysis tools, and, in the first phase, the robust design method (Taguchi) was used to establish which combinations of parameters would be performed in each test, providing us with an L9 matrix. In a second phase, analysis of variance tables (ANOVA) were constructed to select the most significant parameters
Development of Solar Energy Systems Based on High Performance Bulk and Film Thermoelectric Modules
Full text linkAbstract: Due to the increase in energy demand and depletion of natural resources, the development of energy harvesting technologies becomes very important. Thermoelectric devices, based on the direct conversion of heat into electrical energy, are being the essential part of cost-effective, environmental-friendly, and fuel-saving energy sources for power generation, temperature sensors, and thermal management. High reliability and long operation time of thermoelectric energy systems lead to their extensive use in space industry and gas pipe systems. Development and wide application of solar thermoelectric converters (generators) is mainly limited by relatively low thermoelectric conversion efficiency. In this work, we suggest for the first time to use direct conversion of solar energy by systems based on high-performance multistage thermoelectric modules operating in the temperature range of 300 - 900 K for creation of autonomic systems with electric power up to 500 W and electric efficiency up to 15 %. Furthermore, we developed film thermoelectric modules on thin flexible substrates with the figure of merit Z corresponding to that of bulk modules. Such film thermoelectric converters with output voltage of several volts and electric power of several microwatts can be used at micro-solar energy systems
Adaptive Trajectory Planning Method for Robotic Finishing of Concrete Shield Segments
Full text linkTo address the challenges of low efficiency and inconsistent quality in the finishing of concrete shield segments, this paper proposes an adaptive trajectory planning method for a robotic system utilizing point cloud data. The system integrates an automated guided vehicle (AGV), a six-degree-of-freedom serial manipulator, and a 3D vision system to create an intelligent finishing robot. A "rectangular" offline programming trajectory is employed, coupled with multi-coordinate system transformations for precise path mapping. A 3D camera captures the segment\u27s surface point cloud, which is subsequently registered, fused, and analyzed by a neural network to identify surface irregularities and compute a look-ahead tilt angle for adaptive trajectory compensation. Experimental results demonstrate that our method significantly enhances finishing uniformity and surface quality, offering a viable technical solution for the automated finishing of complex curved components
A Detailed Analysis of Backup and Recovery Techniques in Database Management Systems (DBMS)
Full text linkIn this exponential growth age and frequent disruption, data has to be really secure, integral, and accessible. DBMS plays a keynote in all these aspects. This report reviews the backup and recovery techniques of four DBMSs: Cassandra, MongoDB, Neo4j, and Oracle. It discusses their efficacy in restoring data loss and maintaining schema integrity. This study throws light on the challenge of complete data and schema recovery considering operational nuances and system-specific requirements. The recovery processes were recreated in the controlled environments by using hands-on experimentation. Recovery percentages for each DBMS were computed from recovered data. The results of the study indicate that 100% success rate for all systems, which means these systems do not fail in case of a disaster. These results give critical insight into the reliability and application-specific advantages of each DBMS in guiding database administrators in the design of resilient systems
Techno-Economic Assessment of Small-Scale Grid-Connected Solar System in Coastal Cities of Lebanon
Full text linkThe goal of the present study is to examine the economic viability of 12kW grid-connected photovoltaic systems in five coastal cities in Lebanon (Beirut, Tripoli, Saida, Tyre, and Batroun). The results demonstrate that solar energy is a feasible alternative for the nation\u27s sustainable electricity generation, especially in consideration of Lebanon\u27s high levels of solar radiation and rising energy needs. Moreover, a variety of economic indicators, including Net Present Value (NPV), Internal Rate of Return (IRR), Payback Period, Levelized Cost of Electricity (LCOE), and Equity Payback, are computed using RETScreen software. The findings display the profitability for each PV system proposed, where all NPV values are positive and IRRs are above acceptable thresholds. Additionally, Tripoli has the lowest cost of power ($0.0974/kWh) and the lowest payback period (12.40 years), while Beirut has the highest cost and the longest equity payback period. According to the emission investigation, Tripoli avoided the most emissions and also recorded significant greenhouse gas (GHG) savings. According to these findings, solar photovoltaic systems could help Lebanon move toward renewable energy, reduce its negative environmental effects, and promote energy sustainability
Multi-Objective Design Optimization of Thermal Engineering Systems using Rao Algorithms
Full text linkThermal engineering systems include devices or processes where heat transfer plays a major role, such as heat exchangers, refrigeration units, combustion engines, solar collectors, cooling systems in electronics, etc. These systems often have multiple performance objectives like minimizing energy consumption, maximizing heat transfer, reducing costs, improving efficiency and reliability, etc. Design optimization aims to determine the best configuration and parameters for these systems within physical, operational, and economical constraints. The number of objectives considered for optimization may be one or more than one. This study employs three optimization algorithms, known as Rao algorithms, to handle both constrained and unconstrained thermal system optimization problems under single- and multi-objective settings. Their multi-objective extensions-MO-Rao algorithms-are effectively utilized to solve selected two- and three-objective thermal engineering case studies. Additionally, the BHARAT decision-making method is applied to identify the best compromise solution from the set of Pareto-optimal non-dominated solutions. Because the optimization is performed on fast-evaluating RSM models, the obtained Pareto fronts can be readily integrated into intelligent energy management frameworks, where real-time operating conditions can be mapped to pre-optimized design or control configurations. Researchers and practitioners across scientific and engineering domains may find these algorithms advantageous in solving real-world, constrained, and non-convex single-, multi-objective optimization problems
UV Light-Induced Degradation of Industrial Silicon HJT Solar Cells: Degradation Mechanism and Recovery Strategies
Full text linkAbstract: The demand for Silicon heterojunction solar cells (HJT) has significantly grown recently. These solar cells have gained recognition for their remarkable performance, which can be attributed to the exceptional passivation properties of bilayers consisting of intrinsic and doped hydrogenated amorphous silicon. This study investigates alternative recovery methods and looks into the deterioration caused by UV radiation in commercial Silicon HJT solar cells. The carrier lifetimes of the samples were measured before and after the HJT solar cells were exposed to ultraviolet radiation. The findings revealed a decrease in carrier lifetime, iVoc, and iFF, indicating the creation of defects in the bulk of a-Si:H and the interface between c-Si and a-Si:H. It was assessed how SiOx performed as a passivation layer. It has been discovered that SiOx can passivate dangling bonds, increase carrier lifetime and reduce trap density. In addition, recovery techniques like current injection, infrared, light soaking, and annealing were applied. The current injection, infrared, and light soaking treatments were discovered to be able to partially restore the efficiency of the solar cells without the combination of temperature, while annealing was found to be more effective. Additionally, the effects of both short and prolonged exposure to UV are investigated. The HJT solar cells exposed to prolonged UV radiation for an extended period of time could not fully regain their efficiency and displayed irreparable flaws. Overall, this study demonstrates the potential of recovery treatments and passivation techniques in increasing the efficiency of Si HJT solar cells and illuminates the processes underlying ultraviolet-induced deterioration. Overall, this study sheds light on ultraviolet-induced degradation mechanisms and highlights the potential of recovery treatments and passivation techniques in enhancing the efficiency of Si HJT solar cells