微重力落塔落舱释放控制振动信号的小波分析

论述了微重力落塔落舱电磁悬吊、释放、提升控制系统的关键技术,结合电磁释放系统特点,分析了释放时振动信号的特点,介绍了应用小波分析方法进行信号去噪的基本原理.基于阈值小波变换去除振动信号高、低频噪声,然后应用小波包分解方法获取信号的特征量从而进行信号的重构,消除瞬态突变干扰信号,并对系统结构和组成进行了分析.实验结果表明:该方法可以有效地进行信号的消噪,并获取真实的释放振动信号.     

超临界二氧化碳与异丁醇二元体系气液相互溶解度模型的研究

采用可变体积可视观察法测量装置,测定CO_2与异丁醇在40℃-80℃温度范围和不同压力下的平衡数据。研究高压状态下CO_2在液相中的溶解度和异丁醇在气相中的溶解度模型,以改进亨利定律和Chrastil半经验溶解度方程,提出适合于高压下CO_2与异丁醇二元体系的相互溶解度模型,其中CO_2在液相中的溶解度可用4次多项式模型关联,其形式为:P_(CO_2)=A+B_1·x~(CO_2)+B_2·x_(CO_2)~2+B_3·x_(CO_2)~3+B_4·x_(CO_2)~4。异丁醇在CO_2中的溶解度可用改进的Chrastil半经验溶解度方程模拟,其形式为C=p~k·exp(α/T)+b。结果:所提出的气相溶解度方程和液相溶解度方程与试验数据非常吻合,拟合相关系数和精度较高。     

热传导反问题中相变界面的实时跟踪

针对固体融化过程中液体与固体之间相变界面的实时跟踪问题,建立了由固定边界上得到的温度和热流到其相变界面轨迹的辨识及跟踪算法。由于在实际过程中无法在液体边测量其温度和热流,因此,该类问题无法通过直接Stefan问题的求解来得到相变界面的实时跟踪。将其归结为一类不适定反Stefan问题的求解,给出了基于Tikhonov正则化方法的滑动区间优化算法。     

提高液体中石英晶体传感器频率稳定度的方法

石英晶体传感器的动态阻抗显著增大,品质因数下降是液体阻尼负载作用的主要效果。本文从分析液体中石英晶体谐振器的相位平衡条件出发,研究了影响传感器频率稳定度的因素;由石英晶体谐振器的能量局部化效应,分析了传感器液体测头设计中的问题,并由此设计出在液体中工作的石英晶体传感器。实验结果表明,此传感器在液体中具有较高的频率稳定度。     

分子模拟在反相液相色谱分离机理研究中的应用

分子模拟技术是近些年发展起来的一门新兴计算化学技术。本文简要介绍了四种常用的分子模拟方法在反相液相色谱分离机理研究中的应用。详细阐述了采用分子动力学模拟法研究固定相的烷基链构象变化、流动相中溶剂分子与溶质分子间相互作用等与溶质的色谱保留过程的关系。     

全过程跟踪审计在土建施工中的应用

土建工程项目的建设是极其广泛的,生产生活中的工程项目都离不开土建施工,而土建施工的过程则是十分复杂的,那么,如何在施工过程中有效地控制工程造价则成为重点研究的课题。论述了全过程跟踪审计在土建施工中的应用方案,以期为相关审计单位、组织在开展审计工作时提供一定的参考。     

ZnO压敏陶瓷液相低温烧结技术的研究进展

阐述了ZnO压敏陶瓷烧结过程中的液相传质机构，重点论述了传统铋系ZnO压敏材料的液相低温烧结研究方向，以及钒系和玻璃系两种新型ZnO压敏材料的低温液相烧结及其存在的问题。     

直扩QPSK系统中Costas环原理及其实现

介绍了某直接序列扩频、QPSK调制系统接收通道中四相Costas载波跟踪环的原理及其基于DSP+FPGA的实现。着重论述了跟踪环的鉴相特性和环路滤波器的设计和参数计算。     

铜精炼阳极炉氧化过程铜液温度软测量模型及应用

基于铜精炼阳极炉氧化过程热工机理,建立了铜精炼阳极炉氧化过程铜液温度软测量模型,在铜液温度软测量的算法设计中采用数据预处理、黄金分割法搜索区间以及软测量模型参数校正等技术。实际应用结果表明,铜精炼阳极炉氧化过程铜液温度软测量可以反映氧化过程铜液温度的真实变化,有助于实现铜精炼阳极炉精炼过程铜液温度软控制以及提高铜精炼过程的生产效率和生产质量。     

集流型流体电容仪测量井下油水两相流的含水率

对集流型流体电容含水率计在井下油水两相流高含水时应用的可行性进行了研究。建立了泡状流、水为连续相时传感器的等效电路模型。该模型认为在泡状流、高水矿化度、水为连续相的情况下，传感器只敏感于碰撞到内电极绝缘介质层上的油滴。在通常的测量条件下，传感器仍具有较高的灵敏度。为验证理论的正确性，设计了四个静态实验，并进行了模拟井动态实验。实验结果与理论预测完全一致。     

Performance of punctured convolutional codes in asynchronous CDMA communications under perfect phase-tracking conditions

In this paper, the performance of punctured convolutional codes of short constraint lengths is discussed. The punctured codes are used to provide error protection to a particular user in an asynchronous code division multiple access (A-CDMA) system. Perfect channel estimation is assumed at the receiver. A slow fading Rician or Rayleigh channel is assumed. Maximum likelihood decoding through a Viterbi algorithm is used to decode the received symbols. Soft decision decoding for perfect phase tracking of the received signal is considered. Analytical bounds, which are useful in predicting the performance of the A-CDMA system are derived and plotted for the cases of infinite and finite channel memory. The upper bounds with Viterbi decoding are derived and plotted for the various punctured codes considered. The simulated results are found to agree very well with their upper bounds and predicted results.     

遥感与地理信息系统技术在湿地研究中的应用

基于遥感和地理信息技术,对黄河三角洲河口湿地土地利用/覆盖现状和变化进行分析,利用多维信息图像对土地利用状况进行分类,然后利用景观分析法对该地区土地利用/覆盖变化信息进行评定,并对变化驱动力做出推断,最后据此提出合理利用和保护黄河三角洲湿地的建议。     

Comparison of two different cooling systems in alleviating thermal and physiological strain during prolonged exercise in the heat

Abstract

This study compared the efficacy of an ice vest comprising of water (WATER) or a water-carbon (CARBON) emulsion on thermophysiological responses to strenuous exercise in the heat. Twelve male cyclists completed three 50-minute constant workload trials (55% of peak power output, ambient temperature 30.4?±?0.6°C) with WATER, CARBON, and without ice vest (CONTROL), respectively. The increase in core body temperature (Tcore) was lower in WATER at 40 (?0.49?±?0.34 °C) and 50?minutes (?0.48?±?0.48 °C) and in CARBON at 30 (?0.41?±?0.48 °C), 40 (?0.54?±?0.51 °C), and 50?minutes (?0.67?±?0.62 °C) as compared to CONTROL (p?<?0.05, ES > 0.8). While heart rate and blood lactate kinetics did not differ between the conditions, statistical main effects in favour of both WATER and CARBON were found for thermal sensation (condition p?<?0.001 and interaction p?<?0.01) and rating of perceived exertion (condition p?<?0.05). Per-cooling with CARBON and WATER similarly reduced Tcore but not physiological strain during prolonged exercise in the heat.

Practitioner Summary: Exercise in the heat is characterised by increases in thermophysiological strain. Both per-cooling with a novel carbon-based and a conventional water-based ice vest were shown to reduce core temperature significantly. However, due to its lower mass, the carbon-based system may be recommended especially for weight-bearing sports.     

Performance enhancement of hybrid personal cooling clothing in a hot environment: PCM cooling energy management with additional insulation

A novel design of personal cooling clothing incorporating additional insulation sandwiched between phase change materials (PCMs) and clothing outer layer is proposed. Performance of four personal cooling systems including clothing with only PCMs, clothing with PCMs and insulation (PCM?+?INS), clothing with PCMs and ventilation fans (HYB), and clothing with PCMs, ventilation fans and insulation (HYB?+?INS) was investigated. Effect of additional insulation on clothing cooling performance in terms of human physiological and perceptual responses was also examined. Human trials were carried out in a hot environment (i.e. 36?°C, RH = 59%). Results showed that significantly lower mean skin/torso temperatures were registered in HYB?+?INS as compared to HYB. In contrast, no significant effect of the use of insulation on both skin and body temperatures between PCM and PCM?+?INS was observed. Also, no significant difference in thermal sensations, thermal comfort, and skin wetness sensation was registered between cooling systems with and without additional insulation.

Practitioner Summary: Hybrid personal cooling clothing has shown the ability to provide a relatively cool microclimate around the wearer’ body while working in hot environments. The present work addresses the importance of cooling energy saving for PCMs in a hot environment. This work contributes to optimising cooling performance of hybrid personal cooling systems.     

选煤厂中煤浓缩机药剂添加自动控制系统的设计

本系统运用PLC控制系统来代替传统的继电器逻辑控制系统,以提高系统的可靠性,灵活性,降低故障率和系统维护费用。系统运用液位检测装置采集液位信号,接近开关采集位置信号,并运用PLC控制器作为信号处理单元处理输入信号并控制各电动执行机构按程序设定运行,实现药剂系统的注水,药剂添加,搅拌,向药剂存贮池注药,给浓缩机加药的全自动控制并实现系统实时监测及故障报警。     

AJAX技术在高校毕业生就业跟踪管理系统中的应用

高校毕业生就业跟踪管理信息化和网络化是高校教育信息化工作的一项重要内容。针对高校毕业生就业跟踪管理系统运行过程中交互多、读取服务器数据量大的特点,提出了基于ASP.net AJAX技术的就业跟踪管理系统B/S架构设计方案,将AJAX技术应用在用户信息验证、数据更新、数据显示动态排列、多级选择联动等交互操作页面,极大程度地减少了系统交互的响应时间,提高了系统运行效率,增强了用户的体验。     

气液两相流电导传感器测量波动信号的Wigner-Ville分析

流型是两相流中非常重要的流动参量,不同流型下的两相流流动特性及传热传质性能有很大不同。流型也严重影响着两相流参数测量的准确性。利用新近研制的两相流电导传感器,在垂直上升气液两相流管中采集了不同流型下的电导波动信号,采用W igner-V ille分布(WVD)在时频域内处理了电导波动信号,观察到了WVD特征与流型之间的关系,取得了较好的气液两相流流型辨识效果。     

原油含水率测量多因素影响的数值模拟与实验研究

基于介电常数法测量原油含水率,往往受油水两相流态、温度、矿化度、非线性特性等多因素的影响.因此,设计一套基于多传感器的油水两相流实验室模拟系统,利用理论计算结合数值模拟的方法,研究含水率、温度、矿化度、油水介电常数、含水测最传感器输出之间的数学关系及影响规律,对提高测量含水率的精度提供了有力的理论和实验依据.     

Distribution of the minimal completion time of parallel tasks in multi-reward semi-Markov models

The completion time of parallel tasks executed on a randomly varying system is represented as the barrier hitting time in a multi-reward stochastic model. The work produced by the system is calculated by means of two types of functionals that account for different mechanisms of accumulation of the reward in physical systems. The work requirement of each parallel task is assigned as an absorbing barrier acting on the corresponding functional. The distribution of the first time at which one of the functionals hits its barrier is investigated. If the barrier levels are assumed to be PH random variables, the hitting time becomes a PH random variable and the completion time problem is converted into the solution of a suitable expanded Markov chain.