淬火或渗碳淬火钢齿轮传动多目标优化模型分析

本文列出了三种淬火或渗碳淬火钢硬面齿轮传动多目标优化的数学建模方案，分析了各方案的特点，以利于此类齿轮传动的优化设计。     

基于单片机的润滑油调合釜温控系统的设计

本设计是微机反馈控制系统的一个重要应用．他可用于检测三点温度，实现对三点温度的实时控制．井具有温度报警功能．同时。它还能够对压力及流量进行检测．该系统的核心部分是单片机，由它来完成对被测量进行数据采集．处理以及输出控制量进行控制等功能．本控制系统精度高，具有较强的抗干扰能力．井且成本较低。     

Analysis of combustion and flame propagation characteristics of LPG and Gasoline fuels by laser deflection method

This work is to investigate the combustion characteristics and flame propagation of the LPG (liquified petroleum gas) and gasoline fuel. In order to characterize the combustion processes of the fuels, the flame propagation and combustion characteristics were investigated by using a constant volume combustion chamber. The flame propagation of both LPG and gasoline fuels was investigated by the laser deflection method and the high-speed Schlieren photography. The result of laser deflection method show that the error of measured flame propagation speed by laser method is less than5% compared with the result of high-speed camera. The flame propagation speed of the fuel is increased with the decrease of initial pressure and the increase of initial temperature in the constant volume chamber. The results also show that the equivalence ratio has a great effect on the flame speed, combustion pressure and the combustion duration of the fuel-air mixture.     

Thermal investigation of an infrared reflow oven with a convection fan

A two-dimensional numerical model for an infrared reflow soldering with a convection fan is used my modifying the Eftychiou’s numerical modeling. The two-dimensional tunnel model which predicts convective conditions within the reflow oven are solved using the finite volume method with the SIMPLER algorithm. The card model solves the transient two-dimensional heat conduction equation in conjunction with a radiative heat transfer analysis. We also performed an experiment to validate the numerical modeling. The numerical result shows excellent agreement with experimental data. Based on the capability of this model, parametric simulations are performed to determine the thermal response of the solder to variations in the oven operating conditions and heat transfer conditions. This study shows that radiation and conveyor velocity are important factors in the preheat region.     

变频调速技术在煤矿企业的推广应用

以变频调速技术为核心的交流传动与控制技术是目前发展最为迅速的技术之一，有专家认为包括变频技术在内的电力控制技术和计算机技术将成为2l世纪重要的两大技术，传统的电气传动技术正面临着一场历史革命。变频调速是变频技术应用的一个重要方面，是强弱电混合、机电一体化的综合技术。     

基于爬壁机器人技术的油罐容积测量新方法的研究

大型石油储油罐经过长期使用后 ,会由于油罐变形而导致其容积变化。因此需要在油罐的使用过程中对其容积进行重新测量。通常采用的传统测量方法 ,如光学参比法和围尺法 ,其操作者的劳动强度大 ,操作危险 ,测量效率低。本文提出的基于爬壁机器人技术的油罐容积测量新方法 ,在此称为自移动法 ,该方法由爬壁机器人绕油罐爬行 ,通过安装于机器人上的一系列传感器而测量计算出油罐容积。该方法提高了测量的自动化程度和测量效率 ,并满足测量精度的要求     

海岸线防波发电装置研究

针对海洋波浪能量这一可再生清洁能源,分析国内外开发利用的现状,研究目前典型波浪发电技术特点,提出新型连杆浮筒式波浪发电装置,还研究了利用共振和优化液压设计以提高转换效率的措施。该装置能够有效地吸收储存波浪能量并转换利用,还能够克服海水潮位的不利影响并对岸堤起防波保护作用,没有水下运动机构,防锈蚀可靠性高,技术方案经济易行,具有一定的推广价值。     

Optimization of a hydrogen liquefaction process utilizing mixed refrigeration considering stages of ortho-para hydrogen conversion

The ortho-to-para hydrogen conversion (OPC) is an integral part of the hydrogen liquefaction process. The optimal stages and conversion temperatures of OPC are important to reduce the specific energy consumption (SEC) of the process. However, a limited number of studies directly discuss this aspect of the effect of the OPC stages on the SEC. Therefore, based on an efficient refrigeration liquefaction cycle, this paper analyzes the effect of different OPC stages on the SEC of the efficient refrigeration cycle. Additionally, the impact of different combinations of conversion temperatures for the same OPC stages on the SEC is investigated. Results are obtained using a process model developed in HYSYS V10 and the particle swarm optimization algorithm in MATLAB. The results show the impact of OPC stages on the SEC, and that the increase in the stages of OPC can reduce the SEC, but the reduction tends to be slow. The SEC of the five-stage OPC process decreases by 16.39% compared to the SEC of the one-stage. Furthermore, the reduction of SEC for the process with the same stages of OPC can be achieved by setting the optimal combinations of conversion temperatures, which can reduce the SEC by up to 10.63%. The results of this study demonstrate that optimizing the OPC stages is important to reduce the SEC and will provide valuable information for the design of OPC for hydrogen liquefaction processes.     

Morphology effects in MgH2 anode for lithium ion batteries

In order to acquire reproducible electrodes relevant for Li ion batteries new MgH₂ electrodes are successfully obtained from homogenous slurries in N-Methyl-2-Pyrrolidone “NMP” solvent. The electrodes are aimed to elucidate the contribution of the cell components to the electrochemical cycling, in terms of morphology and composition. Various electrode preparations were tested and compared regarding their interaction with Li in a half-cell. The obtained electrochemical cycling curves are discussed according to the ball-milling-induced structural morphology changes and presence of carbon additives, along with the effect of the kinetic rate on the conversion reaction mechanism.     

Minority carrier lifetime and efficiency improvement of multicrystalline silicon solar cells by two-step process

Impurities and defects are of significant interest in multicrystalline silicon, due to the detrimental effect they can have on carrier lifetimes and electrical properties. In view of that, it is important to incorporate certain processing steps to decrease the recombination activities. In this study, a novel experiment was applied as a beneficial approach to improve the electronic quality of low-resistivity mc-Si substrates via a two-step process. Initially, the first step involves gettering multicrystalline substrates using sacrificial porous silicon layer on both sides, which was introduced as a simple sequence for efficient extrinsic gettering schemes. The gettering experiment was performed at 600–900 °C, and optimum results were obtained at 900 °C. Then, the second step involves coating the front surface of gettered mc-Si at 900 °C with vanadium oxide that serves as an excellent antireflection layer and leads to improve furthermore the electrical properties. Significant improvements were obtained after the deposition of vanadium oxide antireflection coating, in view of the fact that gettered mc-Si substrate at 900 °C provides the highest minority carrier lifetime and the lowest effective surface recombination velocity. An overall increase of the electrical properties was obtained after the described two-step process. The conversion efficiency increases from 6% (reference) and reached 13.7%.