Analysis of four change detection algorithms in bi-temporal space with a case study

Although change detection algorithms for temporal remote sensing images have been compared using various datasets, there is no general agreement on their performance for separating change and no-change. This study compared image differencing, image ratioing, image regression, and principal component analysis (PCA) from a mathematical perspective. Error analysis showed that no-change pixels with errors are expected to be located within an error zone in bi-temporal space. Bi-temporal space consists of two temporal axes of target pixel values observed successively. All algorithms confine a no-change area to a zone delineating change and no-change pixels in the space. Image ratioing defines a fan-like sector as a no-change area, generally unsuitable for change detection. The other algorithms confine a no-change area to a strip-like zone. Image differencing defines a no-change zone with a fixed slope, leading to its inability to specify flexibly the error zone that varies with different conditions. In the examined case, image regression and standardized PCA (SPCA) achieved the best performance for change detection, followed by PCA, image differencing, and image ratioing.     

Preparation,analysis, and isothermal crystallization behavior of poly[1,3‐bis(aminomethyl)cyclohexamethylene oxamide]

Poly[1,3‐bis(aminomethyl)cyclohexaneoxamide] (PBAC2) was synthesized using 1,3‐bis(aminomethyl)cyclohexane (BAC) and dibutyl oxalate (DO) via spray/solid‐state polycondensation (SSP). The structure of the synthesized polyoxamide was confirmed by ¹H‐nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. The weight average molecular weight (M_w) of the polyoxamides prepared was 1.35 × 10⁵. The polyoxamides showed excellent thermal properties with glass transition temperature (T_g) of 150 °C, melting temperature (T_m) of 318 °C, crystallization temperature(T_c) of 253 °C, and initial degradation temperature (T_d) of 417 °C suggesting higher thermal stability than commercial polyamide 6 (T_d = 378 °C). Kinetic studies of PBAC2 predicted a two‐dimensional crystal growth. X‐ray diffraction powder diffraction suggested that the polymer has high crystallinity. A saturated water absorption of 2.8 wt % was recorded for the new polyoxamide, giving it a competitive edge for applications in civil aviation, reinforced plastics, and electronics industry where precise dimensional stability and high thermal resistance properties are a priority. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46345.     

高油酸葵花籽油煎炸过程中MCPD酯及缩水甘油酯的变化

以高油酸葵花籽油为煎炸用油对鱼排、鸡块和薯条进行煎炸实验,探究3-氯丙醇(3-MCPD)酯、2-氯丙醇(2-MCPD)酯和缩水甘油酯在煎炸过程中的变化。结果表明:原油中3-MCPD酯、2-MCPD酯及缩水甘油酯含量分别为0.26、0.05 mg/kg和0.58 mg/kg;在煎炸过程中2-MCPD酯含量与3-MCPD酯含量呈现极显著相关(p0.01);煎炸油中的MCPD酯在煎炸后有明显的生成;受煎炸材料的影响,3-MCPD酯含量在煎炸鱼排和鸡块体系煎炸12 h时达到最大值,分别为2.22 mg/kg和2.05 mg/kg,而后逐渐下降;3-MCPD酯含量在煎炸薯条体系中变化不大;缩水甘油酯含量则在所有体系中均下降,受煎炸材料的影响,缩水甘油酯分别在煎炸24 h(鱼排)、60 h(鸡块)和96 h(薯条)中基本降解完全。     

面向状态检修的智能变电站二次设备公共信息模型扩展研究

智能变电站的新特点和新变化对智能站继电保护状态检修提出了新要求,智能变电站二次设备公共信息模型是建设新型智能变电站继电保护状态检修的基础。IEC 61970和IEC 61968公共信息模型(CIM)不能为智能变电站继电保护状态检修提供全面的公共信息模型支撑。基于IEC 61970和IEC 61968的CIM基本扩展原则,通过分析继电保护装置物理结构分层以及智能变电站保护控制系统通过网络化二次回路进行信息交互的新架构,扩展了智能变电站继电保护二次设备资源公共信息模型和继电保护二次设备资产公共信息模型。提出了基于IEC 61850的变电站二次设备状态信息模型到智能变电站继电保护二次设备量测模型的模型映射方案,构建了完整的智能变电站继电保护二次设备公共信息模型架构,为智能变电站继电保护状态检修的应用和二次运维管理系统信息的集成和交互奠定了基础。     

四氧化二氮与几种金属材料的相容性研究现状及展望

介绍了火箭推进剂常用的一种氧化剂——四氧化二氮,就目前国内外对四氧化二氮与3种比较常用的金属材料(不锈钢、铝合金、钛合金)的相容性研究现状进行了简单的评述,并对四氧化二氮的腐蚀研究前景进行了展望。     

智能变电站继电保护二次回路在线监测与故障诊断技术

为了提高智能变电站继电保护装置相关二次回路的可靠性,提出一种基于多参信息量的继电保护二次回路在线监测及故障诊断方法。通过对SV、GOOSE、MMS报文的监测及分析,研究了过程层和站控层链路异常信息的特征,并提出了SV、GOOSE网络的断链、数据异常和同步性分析与预警策略。对于继电保护装置,提出二次回路在线状态监测方法、采样值异常、开关量监视及异常预警策略。通过网络报文记录分析装置或保护状态监测及诊断装置,将保护设备及二次回路各环节发生故障时的典型告警信息收集、分析、上传,构建一套继电保护二次回路在线监测与故障诊断系统。     

钢琴涂饰及其发展趋势

钢琴涂料和涂饰工艺的演变,在一定程度上成为近代涂料技术发展的一个微观缩影。从科技和历史的角度对钢琴涂料依次从天然树脂漆、大漆、硝基漆、聚酯漆和聚氨酯涂料进行回顾,同时探讨了未来钢琴外壳涂饰用水性光固化涂料的发展趋势。     

适用于网页服务器的应用型入侵检测系统

网页服务器用来传递或处理各种信息,网络攻击手法日新月异,造成诸多攻击手法可以很容易地被实现,多数的入侵检测系统以入侵特征规则作为检测基础,仅能对已知的弱点做有效的检测;提出一个适用于网页服务器的应用型入侵检测模块,将检测模块直接嵌入于网页服务器中,以“异常行为检测”和“错误行为检测”的办法,确认攻击类型,有效地预防新型攻击行为与检测已知攻击事件,对提高系统的安全性有重要作用。     

NUMERICAL ANALYSES OF DESIGN AND ASSEMBLY FOR MAIN COMPONENTS OF BESIII

The design and manufacture of the main drift chamber(MDC) and the electro-magnetic calorimeter are most important issues in Beijing electron-positron collider upgraded projects. The whole mass of electro-magnetic calorimeter (EMC) in BESIII is 40t, thus high stiffness, strength and dynamical properties are required for the design of entire structural of electro-magnetic calorimeter. Based on numerical technique, the strength and the dynamical properties of EMC are analyzed, which provide theoretical reference for the design of entire structural of EMC. The MDC is composed of the elements with 28680 pre-stressed high-sensitive wires and during the assembly the wires are stringed layer by layer. The stretching forces of the wires vary continuously and couple with each other in the whole process. The modeling technique with high precision (especially "element birth and death") is carefully used to study the stress state during the process of assembly. So the variations of the stretching force of the wire are investigated, and several design schemes are evaluated and optimized. The research results have been adopted in the Beijing electron-positron collider's new project directly.     

某大型住宅小区的智能化设计方案

本文简要介绍了某大型住宅小区的智能化设计。