节点两次抛洒的无线传感器网络能耗平衡策略

针对无线传感器网络中的“能量空洞”问题,提出了一种将传感器节点分两次抛洒的能耗平衡策略。基于圆形区域网络的多跳传输方式,分析了无线传感器网络的能耗模型,并在各圆环内对传感器节点进行不均匀抛洒。为了克服节点密度较大圆环采集数据的冗余性,首先在各圆环内等密度抛洒只具有传感功能的节点,第二次抛洒的节点仅作为中继站向相邻圆环转发数据,根据节点平均能耗相等的原则,确定各圆环内的中继节点密度。传感节点和中继节点分别进行抛洒,不仅节省了硬件成本,而且减轻了网络的传输负载。仿真结果表明,该策略能够有效平衡节点能耗,缓解能量空洞问题,从而延长无线传感器网络的生存时间。     

基于Hough变换的SAR图像舰船尾迹检测方法

该文提出了一种基于Hough变换与K均值聚类检测舰船尾迹的算法。该方法通过归一化Hough变换求出原图像尾迹所在直线的平均能量值,由于原图中的尾迹往往并不规则,导致能量最大值并不是整条直线的最佳统计代表值,其周围会有一些能量次大的点出现,且形成一个由若干能量点组成的点集。该文引进了K均值聚类方法,将这些点集归类,归类后的每一类的类心能很好的代表一条尾迹,实验结果表明方法是有效的。     

高能级强夯在湿陷性黄土地区的应用

根据8000、12000kN·m高能级强夯大面积处理地基加固的综合检测试验数据,结合室内试验数据及黄土地区的特殊性,得到了高能级强夯在黄土地区的有效加固深度、湿陷性处理效果;分析了高能级强夯处理湿陷性黄土的加固效果、加固深度及能级变化对地基处理效果的影响。结果表明：该研究为进一步分析高能级强夯的加固机理,尤其在湿陷性黄土地区的加固机理提供了依据,也为高能级强夯的大面积设计、施工和检测提供了优化数据。     

非均相催化湿式氧化活性红2BF的研究

以Fe/AC为催化剂、O2为氧化剂的非均相催化氧化体系处理偶氮染料活性红2BF,考察了反应温度、氧分压、废水pH、催化剂投加量等因素对降解效果的影响。结果表明,染料初始质量浓度为400 mg/L时,在温度150℃、氧分压0.5 MPa、pH=3、反应时间60 min、催化剂投加量为4 g/L的最佳条件下,活性红2BF色度几乎完全去除,TOC去除率达94.21%。     

A new model for evaluating the electrical conductivity of nonferrous slag

Electrical conductivity of molten slag is an important physicochemical property for designing the refining process in electric smelting furnaces.Though conductivities of many slag systems have been measured,the quantitative relationships of conductivity with slag composition and temperature are still very limited.In this article,the Arrhenius law was used to describe the experimental data of conductivities for CaO-MgO-Al2O3-SiO2,CaO-Al2O3-SiO2,CaO-MnO-Al2O3-SiO2,as well as CaO-MgO-MnO-Al2O3-SiO2 systems,and...     

Hydrogen sorption properties of nanocrystalline Mg2FeH6-based complex and catalytic effect of TiO2

The diversities of hydrogen sorption properties of Mg₂FeH₆-based complexes with and without TiO₂ were investigated. Mg₂FeH₆-based complexes with and without TiO₂ were synthesized respectively by reactive mechanical alloying, and hydrogen sorption properties of the complexes were examined by Sieverts-type apparatus. The results show that the sample without TiO₂ releases 4.43 % (mass fraction) hydrogen in 1.5 ks at 653 K under 0.1 MPa H₂ pressure and absorbs 90% of the total 4.43 % (mass fraction) hydrogen absorbed in 85 s at 623 K under 4.0 MPa H₂ pressure. But for the sample with TiO₂ addition under the same condition, it only needs 400 s to release all of the stored hydrogen and 60 s to absorb 90% of the total hydrogen absorbed. The activation energies for desorption process of the samples with and without TiO₂ are determined to be 71.2 and 80.3 kJ/(mol·K), respectively. The improvement in hydrogen sorption rate and and reduction in activation energy can be attributed to the addition of TiO₂.     

A sink moving scheme based on local residual energy of nodes in wireless sensor networks

In the application of periodic data-gathering in sensor networks, sensor nodes located near the sink have to forward the data received from all other nodes to the sink, which depletes their energy very quickly. A moving scheme for the sink based on local residual energy was proposed. In the scheme, the sink periodically moves to a new location with the highest stay-value defined by the average residual energy and the number of neighbors. The scheme can balance energy consumption and prevent nodes around sink from draining their energy very quickly in the networks. The simulation results show that the scheme can prolong the network lifetime by 26%–65% compared with the earlier schemes where the sink is static or moves randomly. Foundation item: Project(60673164) supported by the National Natural Science Foundation of China; Project(20060533057) supported by the Specialized Research Foundation for the Doctoral Program of Higher Education of China     

太阳能制冷技术的特点与现状

太阳能制冷具有环保节能的优点．介绍了各种太阳能制冷技术的原理、特点及存在问题,指出提高太阳能的利用效率和降低成本是其实用化的关键所在。     

分布式能源系统及其运行特性分析

介绍了日本某学术研究都市的分布式能源系统所采用的发电技术和余热利用系统,并对此系统的历年运行数据进行了分析.通过分析发现,燃料电池的余热利用效果不理想,其综合能源利用效率低;而燃气内燃机的余热利用较好,综合能源利用效率达到60%以上.因此提高整个系统的余热利用率是该系统优化运行的重要课题.     

考虑初始弯曲矩形薄壁钢管砼柱管壁屈曲分析

实际工程中的钢管都是有初始弯曲的,初始弯曲的存在会降低薄壁钢管混凝土柱的承载力.采用能量法对具有初始弯曲管壁的屈曲性能进行了分析,分析结果表明,初始弯曲的存在会使管壁的宽厚比降低30%左右.