基于多阶有源带通滤波器和在线相关系数的负载在线智能识别

从时域建立了负载在线识别的数学模型,识别任务由硬件和算法共同承担。采用多阶有源带通滤波器进行硬件预处理,从而将功率相差很大的负载信号转换成可以在同一个条件下采集的电压信号。从皮尔逊相关系数出发定义了在线相关系数,将其作为唯一的时域特征参量,并提出“在线相关系数逐渐增大并最终等于1”的判决准则。利用最大值首位对齐法和均值法进行数据处理,采用逐次比较法和筛选法相结合进行识别。实验数据表明：基于带宽为340～900 Hz的五阶有源带通滤波器和STM32处理器中的在线相关算法很好完成了功率相差1 500多倍的电磁炉、电饭煲、笔记本电脑、小灯泡等4种负载的任意在线组合的智能识别。     

沥青路面降温技术研究进展与展望

沥青路面高温会带来车辙等病害,并增加城市热岛效应,这对路面的使用质量、使用寿命和人类的生活环境产生不利影响,所以急需开发行之有效的沥青路面降温技术,以减少车辙等病害和缓解城市热岛效应。现有的沥青路面降温技术分为被动降温技术和主动降温技术,而主动降温技术能够更为有效地降低沥青路面温度,且具有智能性、自发性等特点。主动降温技术对应的降温沥青路面主要有热反射路面、相变调温路面、热阻路面、透水路面、能量收集路面、高导热路面。针对上述沥青路面主动降温技术,总结了沥青路面主动降温技术的原理特点、应用方式、运用于沥青路面的实际降温及路用效果,以及降温技术的新方法、新思路,探讨了沥青路面主动降温技术的缺陷和局限性,并对未来沥青路面降温技术发展趋势进行展望。     

Web预取技术综述

Web预取是减少用户访问延时、提高网络服务质量的关键技术之一,近年来已成为国内外的研究热点.通过利用WWW访问的空间局部性,Web预取使缓存机制从时间局部性向空间局部性扩展.归纳了Web预取技术的分类,概括和比较了不同类别的优势和局限性,给出了预取模型的基本框架及每部分的主要功能,并对各种评价标准进行了详细介绍.同时,深入分析和探讨了现有的几种典型预取算法,系统地比较了这些算法的优缺点.最后从在线性、协作预取、动态流行度、划分用户会话和基于语义与基于路径相结合等方面指出了Web预取技术的研究方向.     

钙镁复合药剂处理洗煤废水的效果及作用机理研究

用CaCl2与MgS04复配出新的复合药剂,通过试验确定了适宜m(CaCl2):m(MgSO4)=1:1.采用正交实验确定了钙镁复合药剂与PAM联用处理洗煤废水的最佳组合条件,并通过生产性试验验证了实验室的试验结果.分析认为钙镁复合药剂对洗煤废水的混凝机理并不完全符合DLVO理论,它是多方面因素共同作用的结果.     

Mechanical properties of discontinuous fiber reinforced thermoplastics. II. Random-in-plane fiber orientation

The mechanical properties are presented for a series of discontinuous fiber-reinforced thermoplastic composites made with random-in-plane fiber orientation. The matrix and fiber materials were chosen to provide a wide range of strength, modulus, ductility and adhesive properties. In many cases strong, rigid, yet tough composites were fabricated. Strength levels of over 20,000 psi and modulus values over 1,000,000 psi were reached in several systems reinforced with short Kevlar-49 and graphite fibers. A strong dependence of composite strength and modulus on fiber strength and modulus was noted indicating good transfer of load from matrix to reinforcement. Fiber efficiency factors for modulus and strength were calculated for the experimental composite systems and averaged 0.19 and 0.11 respectively. Data were analyzed using basic composite theory. Properties of the experimental composites could not be predicted from constituent properties.     

Oxidation processes in a silicon-boron-zirconium boride composite in the temperature range 1000–1300°C

Silicon, boron, and zirconium boride coatings on graphite have been obtained by thermal treatment of the initial components in air. During the course of the chemical reactions, a glass melt encapsulating (wrapping) the initial particles is formed, which makes it possible to create an air barrier preventing the diffusion of oxygen into the sample. The interactions between the components of the Si-B-ZrB₂ system with oxygen and the glass-forming melt have been investigated.     

Effect of the thermal treatment on the phase composition of the surface of coatings based on Si–B–ZrB<Subscript>2</Subscript> and modified with ZrO<Subscript>2</Subscript> fibers

Coatings on graphite that are stable to oxidation and based on the silicon–boron–zirconium boride composite containing from 5 to 50% of fibrous zirconium dioxide as a modifying dopant have been produced by the suspension–annealing method. A nonporous layer is formed at the zirconium dioxide content ranging from 5 to 15%, while a porous layer is formed at its 50% content. A glass-forming melt, as well as zirconium dioxide and silicate, is formed during thermal treatment as a result of the chemical reactions with the oxygen in air. The zirconium silicate content increases, along with the modifier’s concentration and temperature.