基于随机层次分析法的高校科学研究水平评价

在分析高校科学研究水平评价体系的层次结构以及量化评价中的不确定性的基础上,设计随机层次分析法对高校科学研究水平进行评价.在随机层次分析法中,将专家咨询法过程中的不确定性描述为随机变量,得到随机判断矩阵,进而应用随机模拟方法确定随机判断矩阵中元素的估计值.运用随机层次分析法对3个高校的科学研究水平进行了实证分析,阐明该方法在多个指标、存在不确定性的条件下是一种科学、可行的综合评价方法,同时,针对各高校提出了科学研究中存在的问题和相应的对策建议.     

PV/T太阳能热泵系统的性能研究

提出一种新型的太阳能热泵系统——PV/T-SAHP系统，该系统具有光电/光热综合利用的功能；建立了PV/T-SAHP系统的动态模型，对该系统的运行特性进行了数值模拟。结果显示，PV/T-SAHP系统的电效率和热效率较传统的太阳能系统和热泵系统都有明显提高，运行能耗较普通热泵大幅度降低；系统PV/T蒸发器的面积、管间距、倾角等参数的变化对电效率和热性能会产生比较大的影响，是系统优化设计的关键因素。     

Performance analysis of a photovoltaic heat pump

A novel heat pump system is proposed in that the PV/T collector is coupled with a solar assisted heat pump and works as an evaporator. The cooling effect of the refrigerant allows the PV modules to work at lower temperature and so its photovoltaic efficiency is improved. Mathematical model has been developed to analyze the complex energy conversion processes. Numerical simulation was then performed based on the distributed parameters approach. An experimental rig was also built to verify the real performance of the system as compared to the simulation model prediction. The results indicated that this photovoltaic solar assisted heat pump (PV-SAHP) has better coefficient of performance (COP) and photovoltaic efficiency than the separate units. Under the experimental conditions, the COP of the PV-SAHP reached 8.4 and the average value was around 6.5, whereas the average photovoltaic efficiency was around 13.4%. The experimental results were found in good agreement with the theoretical predictions on the system responses to changing environmental conditions.     

太阳能集热器与热泵联合供暖装置的实验研究

新能源开发与节能是解决能源短缺的两个关键途径,太阳能热泵(SAHP)系统因其突出的节能与环保特点而具有广泛和美好的前景.作者介绍了太阳能集热器与热泵联合供暖的实验装置,为了观察和测试系统和各部件的性能,对该装置进行了系统测试,获得了设计、安装和运行方面的资料,初步得出了若干有用的结论.     

基于LED半功率角的VLC混合室内定位算法研究

提出一种基于LED半功率角的VLC混合室内定位算法,该算法结合LED半功率角特点,在LED半功率角覆盖范围内时,光信号强度大、信道条件好,信号受到的路径损耗影响小,使用半功率角RSS算法进行定位;在LED半功率角覆盖范围外时,光信号强度小、信道条件差,提出到达角差值算法进行定位,该算法受光信号强度值大小的影响小,且只需2个LED信源可实现室内三维空间定位.最后,使用Matlab仿真,并利用卡尔曼滤波消除算法定位误差,将定位误差减小到2 cm.基于LED半功率角的VLC混合室内定位算法复杂度低、定位精度高,且实现简单.     

基于LED半功率角的IRT-N三角阵列研究

在可见光通信(VLC)室内定位领域中,LED半功率角辐射范围内信号强度大,运用测距算法时定位误差小。为了提高室内LED半功率角的辐射范围,并消除其辐射"盲区",提出了一种基于LED半功率角的IRT-N三角阵列,该阵列通过利用地面上的LED半功率角圆形辐射范围相切,将LED组合排列成等腰直角三角形。相较于传统斯派罗法则构建的方形阵列,IRT-N三角阵列将地面接收信号强度和接收功率高于平均值的辐射面积分别提高了25.75%和16.45%。该阵列构建复杂度低、半功率角辐射范围广,更适宜在VLC室内定位领域中推广应用。     

Thermal analysis of PV/T evaporator of a solar-assisted heat pump

The performance of photovoltaic/thermal (PV/T) solar collector had been studied theoretically and experimentally for some years. Air and water streams were used as the heat carriers for space heating or services hot water systems. The cooling effect allows the PV module to work at lower temperature and its PV efficiency is therefore improved. However, such an advantage diminishes when the solar irradiance is high. To improve the situation a new type of PV/T collector is proposed. It works as the evaporator of a heat pump, in that refrigerant evaporates in the tubing at the back of the flat-plate collector and the PV module is adhered to the front surface. Mathematical models were developed to simulate the complex energy conversion processes. Numerical analysis was then performed based on the distributed parameters approach. An experimental rig was also built to test its real performance. Our results showed that the PV/T evaporator had an overall efficiency in the range of 0.64–0.87, thermal efficiency 0.53–0.64 and PV efficiency 0.124–0.135. The simulation results were found in good agreement with the experiment measurements. Copyright © 2006 John Wiley & Sons, Ltd.     

基于随机层次分析法的虚拟企业风险评价

分析虚拟企业风险因素的层次结构以及量化评价中的不确定性,设计了随机层次分析法(SAHP)来对其风险进行评价.在随机层次分析法中,将专家咨询法过程中的不确定性描述为随机变量,得到随机判断矩阵.进而应用随机模拟方法确定随机判断矩阵中元素的估计值.运用随机层次分析法对某虚拟企业三个备选组建方案的风险评价进行了实证分析,阐明该方法对于多指标、不确定性的最优方案选择问题是一种科学、可行的方法.