Performance modeling of data transmission by using random linear network coding in DTNs

In Delay Tolerant Networks (DTNs), mobile nodes exploit encounter chances to transmit data via the established opportunistic link between encounter nodes. The transmission capacity between two encounter nodes is constrained by the duration of opportunistic links. How to transmit data efficiently is one of the fundamental and most important issues in DTNs. Recently, Random Linear Network Coding (RLNC) is proposed as a promising approach to improve data transmission efficiency in DTNs. To facilitate the development of deployment of RLNC based routing protocols, it is imperative to quantify the performance gain brought by RLNC in a rigorous and systematic way. In this paper, we develop an analytical model to evaluate the data transmission performance of RLNC based epidemic routing in DTNs. In the model, we consider that multiple unicast communication sessions compete for limited \capacity. Numerical results validate the effectiveness of our analytical model and demonstrate the significant performance improvement for data transmission in DTNs brought by RLNC. Our work of this paper provides a general tool for performance evaluation and useful guidelines for designing RLNC based routing protocols in DTNs. Copyright © 2015 John Wiley & Sons, Ltd.     

Fast Transmission Photothermal Radiometry via Sampling by an Internal Computer Sound Card

During the last few decades, photothermal radiometry (PTR) has been greatly developed and widely applied in the field of nondestructive testing. However, the traditional PTR system employs an expensive lock-in amplifier to detect the weak photothermal signal, which leads to high cost and long test time. In this paper, a fast transmission PTR system based on sampling by using an internal computer sound card was developed to lower the system cost and shorter the test time. A piece of amorphous silicon (a:Si) thin film solar cells with artificial defects was prepared and tested by the system. The results show that the sharpened defects can be identified easily and quickly according to the significant peaks of the original infrared signal sampled by the internal computer sound card. Furthermore, more detailed defects can be investigated by processing the infrared signal. These validate the effectiveness of the proposed transmission PTR system as a low cost and efficient non-destructive test technique.     

限量供氧对粟酒裂殖酵母絮凝颗粒酒精发酵的影响及连续发酵工艺的研究

本文以双酶法制备的淀粉糖化糖为底物,首先通过摇瓶分批式发酵实验,研究了限量供氧对粟酒裂殖酵母絮凝颗粒酒精发酵性能的影响,发现限量供氧可以使酒精发酵过程的增酸降低,同时能够有效地阻止絮凝颗粒酵母长期连续使用时发酵活性的衰减。维持颗粒的良好絮凝状态,但发酵终点的残糖有所增高。在此基础上,进行了三级悬浮床反应器串连操作的连续发酵实验,反应器以0.02vvm的通风量使絮凝颗粒酵母均匀悬浮,同时实现限量供氧,当底物糖浓度控制在190～195g几时,反应器以0.165h-1的总稀释率操作,平均设备生产强度达到13.2EtOH/L.h,发酵液中酒精浓度为80.0g/L,总糖转化率为90％。     

电力系统混合优化的模拟进化方法

电力系统中有许多混合优化问题,采用常用方法求解难以奏效,而模拟进化方法是一种新型有效的优化方法,文中提出模拟进化方法中处理混合优化问题的两种办法,即离散变量连续化及连续变量离散化,并将其应用电力系统功率,电容器组的优化问题,结果表明所提方法是可行的。     

适用于任何具体结构的输电线路精确故障定位

针对输电线路的实际结构,提出了一种适用于任何具体结构的超高压输电线路的精确故障定位方法。该方法 基于模分析理论,采用矩阵特征值和特征向量原理,对多导线波动方程进行矩阵相似变换, 得到互相独立的 模量上的波动方程,分别对每个模量波动方程求解后,将计算结果反变换到相量。该方法很好地克服了输电 线参数实际上的不平衡对故障测距精度的影响,既适用于不换位线路 ,也适用于各种换位线路。计算机数字 仿真试验结果表明,其测距结果十分准确。     

城市配电网格化规划探讨

随着城市经济建设和市政功能日臻完善的发展趋势,提出了以网格化概念,规范城市（公用）配电网络的建设和发展,并由此化解目前配电生产组织、营业收费管理以及市政改造发展中的诸多矛盾,为逐步实现城市配电供电高可靠性目标打好基础。     

基于无源性的同步电动机控制器设计

利用无源性理论对同步机设计了磁通,转速和功率因数控制器,分析与仿真表明,得到的控制器不仅形式简单,无奇异点,而且无须转子电流观测器,并在经基础上实现了转速无静差和功率因数的控制。     

湖北省电力科技信息计算机网络开发应用及发展

阐述了湖北省电力科技信息计算机网络的两种运方式：Ｎｏｖｅｅｌ网和ＮＴ网,以及网络的拓扑结构,系统设计和软件硬件技术指标。