基于随机矩阵理论和聚类算法的电能表运行状态评估方法

随着智能配电网络规模的扩大以及电网结构的复杂化,电力大数据呈指数级增长,电力设备的检、监测评估面临新的挑战。在大数据原理和数据挖掘分析的基础上,提出一种基于随机矩阵理论和聚类算法的电能表运行状态评估方法。首先,对电力大数据统一预处理,完成时间序列数据表征;然后,采用实时分离窗技术整合时序数据;其次,基于随机矩阵理论,对多维度电能表时间序列数据实时计算、分析统计量时序特征;进一步,采用改进的时间规整聚类算法计算时序数据相似度,从而对随机矩阵统计量聚类分级;最后,分析聚类结果,得到电能表运行状态评估等级和范围,完成电能表实时运行状态评估。实例分析和对比研究结果表明,与传统的主元分析评估方法相比,所提出的新型电能表运行状态评估方法具有良好的鲁棒性、可靠性和时效性,为电力电网检测技术应用研究提供了新思路。     

Encouraging and supporting electronic communication across the curriculum (ECAC) through a university and K–12 partnership

Critical, sustainable approaches to technology are difficult to develop and integrate within the constantly shifting and dynamic landscape of computers. This challenge is particularly pertinent for K–12 teachers, who often have limited access to computers, work with outdated equipment, or do not have time to tinker with the technology in ways that make it more readily applicable to their classrooms and curricula. In this article, we describe an approach to remedying the technological turbulence that both K–12 and university faculty face. We describe the Electronic Communication Across the Curriculum Summer Workshop,¹ a two-week long physical and virtual course offered to K–12 teachers and their middle and high school students in the Upper Peninsula of Michigan. We offer this workshop as a model approach for other workshop developers, for those interested in educational partnerships, and for those committed to professional development and technology.     

1.5 MPa多喷嘴对置式水焦浆气化炉的模拟与优化

针对w（水焦浆）和氧焦比预测优化过程未采用严格反应机理模型,工艺参数的预测优化与实际生产存在较大偏差的情况,以UniSim Design流程模拟软件为工具,采用Gasifier反应器严格机理模型建立了1.5 MPa多喷嘴对置式水焦浆气化炉模型,并根据工业数据对水焦浆气化炉进行标定,标定结果相对误差小于2%,同时研究了氧焦比和w（水焦浆）对焦煤气化工艺参数的影响。结果表明：w（水焦浆）和氧焦比是影响水焦浆气化过程和粗煤气组成的关键因素,通过气化炉模型标定和优化分析,石油焦的氧焦比控制范围为0.95~1.10,为焦煤浆气化工艺生产实践指导提供了理论依据。     

大管道气体流量检测仪表

介绍了一系列大管道气体流量检测仪表。这些仪表多以速度面积法为基础,采取取样原理、插入安装方式。具有结构简单,安装简便,压损小,性价比较高等特点,但其准确度一般较差。本文对这些仪表进行了分类,介绍其优缺点,并提出了影响测量精确度的主要因素。     

基于区间数的不确定性数据聚类算法:UD-OPTICS

在不确定性数据聚类算法的研究中,普遍需要假设不确定性数据服从某种分布,继而获得表示不确定性数据的概率密度函数或概率分布函数,然而这种假设很难保证与实际应用系统中的不确定性数据分布一致。现有的基于密度的算法对初始参数敏感,在对密度不均匀的不确定性数据聚类时,无法发现任意密度的类簇。鉴于这些不足,提出基于区间数的不确定性数据对象排序识别聚类结构算法(UD-OPTICS)。该算法利用区间数理论,结合不确定性数据的相关统计信息来更加合理地表示不确定性数据,提出了低计算复杂度的区间核心距离与区间可达距离的概念与计算方法,将其用于度量不确定性数据间的相似度,拓展类簇与对象排序识别聚类结构。该算法可很好地发现任意密度的类簇。实验结果表明,UD-OPTICS算法具有较高的聚类精度和较低的复杂度。     

基于AO算法的数据流频繁项集挖掘

In view of a series of problems existing in support update, window update mode and frequent k-itemset mining of traditional frequent itemset mining algorithm in data flow, which results in low efficiency of space and time,an efficient AO algorithm for mining frequent itemsets in data streams is improved. The algorithm uses the idea of sliding window to mine the data stream in blocks; when there is new data flowing in the full window, the residual insertion is used to update the data; and operation is used to solve the support degree of frequent k-itemsets, and the superset detection is combined in the mining process, which greatly improves the mining efficiency.The experimental results show that the algorithm has good superiority in both time and space efficiency.     

恶意USB设备原理及防护措施研究

在网络与信息安全领域中,计算机USB接口安全一直以来都面临着严峻的风险挑战,也是用户最容易忽略的问题,而恶意USB设备是计算机USB接口安全的主要威胁之一,它严重威胁着企业的信息安全与公民隐私信息安全。针对当前USB安全问题现状进行了分析,介绍了常见的恶意USB设备Keylogger与BadUSB的危害、攻击特性,对Keylogger,BadUSB硬件电路原理,硬件程序实现,攻击方法进行了详细剖析。通过AVR微控芯片构建出Keylogger,BadUSB设备,然后用其设备对计算机进行攻击实验,最终实现对目标主机的监听与控制,并研究拦截Keylogger记录监听与抵御BadUSB攻击的安全防护措施,为用户提供有效的安全保护解决方案。这些防护措施与解决方案能有效地保护公共信息安全与个人信息安全,能遏制USB接口层面信息安全事件的发生。     

A novel low-complexity power allocation algorithm based on the NOMA system in a low-speed environment

For future wireless communication systems, Power Domain Non-Orthogonal Multiple Access (PD-NOMA) using an advanced receiver has been considered as a promising radio access technology candidate. Power allocation plays an important role in the PD-NOMA system because it considerably affects the total throughput and Geometric Mean User Throughput (GMUT) performance. However, most existing studies have not completely accounted for the computational complexity of the power allocation process when the User Terminals (UTs) move in a slow fading channel environment. To resolve such problems, a power allocation method is proposed to considerably reduce the search space of a Full Search Power (FSP) allocation algorithm. The initial power reallocation coefficients will be set to start with former optimal values by the proposed Lemma before searching for optimal power reallocation coefficients based on total throughput performance. Step size and correction granularity will be adjusted within a much narrower power search range while invalid power combinations may be reasonably discarded during the search process. The simulation results show that the proposed power reallocation scheme can greatly reduce computational complexity while the total throughput and GMUT performance loss are not greater than 1.5% compared with the FSP algorithm.     

Effects of the Relocation of Chongqing Iron and Steel Group Industrial Area on Regional Ecological Quality

Urbanization is typically accompanied by the reconstruction or relocation of heavy industrial areas due to limited space and high standard environmental requirements.Taking "environment\|friendly relocation" of Chongqing Iron and Steel Group as an example,this study quantitatively compares and analyzes changes of the thermal and ecological conditions before and after the relocation.Main biophysical properties of the study area and land surface temperature(LST) were retrieved from the multi\|temporal Landsat serial satellite images.Urban Heat Island Index(URI) and Remote Sensing based Ecological Index(RSEI) were employed for the study.The results reveal that urban heat island effect of the industrial area was significantly mitigated and the ecological quality was significantly improved after the relocation,suggested by the decline of URI value from 0.387 in 2005 to 0.128 in 2014(a drop of 66.7%),and the rise of RSEI value from 0.398 to 0.553 during the same period(an increased of 38.9%).This is due largely to the halting of steel production,change of land cover types and properties caused by the “environment\|friendly relocation” of the industrial area.In general,the halting of steel production,the decrease of impervious surface and the increase of vegetation coverage can mitigate the heat island effect and improve the ecological quality.The result of this study can provide a useful case for reconstruction or relocation of urban heavy industrial area and promotion of city’s healthy sustainable development.     

LTE-A空口监测分析仪中载波聚合的设计与实现

针对载波聚合等关键技术的引入造成通信网络测试及优化困难,长期演进（LTE）网络空口测试仪表国内市场短缺的问题,提出一种支持3GPP R10/11协议标准,LTE演进（LTE-A）载波聚合等关键技术的空口监测分析仪的设计方案。首先,介绍空口监测分析仪整体物理架构及逻辑架构及两者之间的关系,及架构中各模块在监测仪中的功能;然后,设计一种监测仪中载波聚合技术的实现方案,以及一种仪表在多载波多小区情况下对多用户的支持方案,以满足新技术下用户及基站设备测试的需要。方案的应用,可加快载波聚合在网络中的商用进展,加速LTE-A网络部署进程,缩短网络建设周期,并将在网络运行维护中起到不可或缺的作用。