Electron beam induced structural evolution in Fe3O4SiO2 particles: A new route to obtain movable core structures

SiO₂ hollow spheres with movable Fe₃O₄ core were obtained by exposing the pre-synthesized Fe₃O₄SiO₂ particles (with an adsorption interlayer of ethylene glycol) under the irradiation of electron beam inside transmission electron micrograph (TEM). In the formation process, the evaporation of adsorbed ethylene glycol and the evolution of amorphous SiO₂ layer played important roles, and that should be attributed to the high temperature and trapped charges induced by the irradiation of electron beam. This work provided a new route to obtain particles with movable core structure and extended the applications of electron beam.     

Microstructure and Transport Properties in Tin Boned La<Subscript>0.7</Subscript>Sr<Subscript>0.3</Subscript>MnO<Subscript>3</Subscript> Composites

A novel boned perovskite manganese oxide magnetoresistant material was prepared using La_0.7Sr_0.3MnO₃ (LSMO) as the precursor powders and metal tin (Sn) as the binder. The microstructure and phase characteristics, low-field transport properties were studied. Sn segregated at the grain boundaries of LSMO grains. The insulator–metal (I–M) transition and enhanced LFMR are only observed with a low content of Sn, due to grain boundary disorder and spin polarized tunneling between grain boundaries. The Sn addition induced resistivity decreasing dramatically. In the high temperature PM region, the resistivities for samples with low Sn content follow the adiabatic small-polaron-hopping model.     

巴西、阿根廷、古巴三国照明产品质量监管体系及其对我国的启示

阐述了巴西、阿根廷、古巴节能产品质量监管的基本情况,系统分析对比了巴西、阿根廷、古巴以及欧美等国的照明产品质量监管体系的特点和有益经验。在此基础上,提出了建立健全我国照明产品质量监管体系的若干建议。     

冰箱门封导热性能及影响因素的CAE分析

由于冰箱门封对于节能非常重要,本文利用CAE仿真技术,采用二维平面模型对多款冰箱门封进行仿真研究,为冰箱门封和冰箱的性能设计和优化提供理论依据。通过对典型冰箱门封导热性能的分析,找出影响门封导热性能的因素,同时,以某型号冰箱为例,研究门封对冰箱漏冷量的影响。仿真结果表明,门封结构及磁条是门封导热性能的重要因素;门封等效导热系数约为0.05W/(m·K);冰箱门封漏冷占冰箱总漏冷约8%;门封高度从10mm减小为7mm时,冰箱门封漏冷比率减小约2.3%。     

宽水压进水系统及其洗衣机的研究应用

本文通过对现有进水阀结构和控制方式的改变,实现在较低水压下的较大流量进水,满足低水压情况下全自动洗衣机的进水要求,同时兼顾正常水压情况下的洗衣机使用,使之更适用于广大农村市场。同时,避免活塞帽在隔膜板活动空间内抖动产生的噪声,给消费者带来不便。     

Deterministic Sensing Matrices Based on Multidimensional Pseudo-Random Sequences

An approach is proposed for producing compressed sensing (CS) matrices via multidimensional pseudo-random sequences. The columns of these matrices are binary Gold code vectors where zeros are replaced by ?1. This technique is mainly applied to restore sub-Nyquist-sampled sparse signals, especially image reconstruction using block CS. First, for the specific requirements of message length and compression ratio, a set Λ which includes all preferred pairs of m-sequences is obtained by a searching algorithm. Then a sensing matrix A _M×N is produced by using structured hardware circuits. In order to better characterize the correlation between any two columns of A, the average coherence is defined and the restricted isometry property (RIP) condition is described accordingly. This RIP condition has strong adaptability to different sparse signals. The experimental results show that with constant values of N and M, the sparsity bound of A is higher than that of a random matrix. Also, the recovery probability may have a maximum increase of 20 % in a noisy environment.     

基于TRIZ理论对电子商务与分销商冲突解决的研究

为了解决电子商务平台发展应用与分销商之间的利益问题,采用TRIZ理论的理想解分析方法以及商业冲突矩阵,对此进行了分析阐述。最终给出可行的发明原理及原理所对应的解决方案。进一步验证了TRIZ理论在商业管理中应用的可行性。     

基于PLC、触摸屏、电子模块的蔬菜大棚监控系统

以DVP-SS-11R型PLC为蔬菜大棚温湿度控制中心,利用DOP-B07S201型触摸屏显示,设定温湿度值以及报警的上下限值,使用电子模块DVP-04PT、DVP-04AD以及温度传感器PT100和湿度传感器HM1500对蔬菜大棚的温湿度进行检测,实现对蔬菜大棚温度和湿度的控制。     

蜂箱内多点温度检测系统

介绍了基于AT89C52单片机的蜂箱内多点温度检测系统软、硬件结构设计。详细介绍了PN结温度传感器的工作原理以及在温度采集系统中的应用;AD0809在A/D转换中的应用;最后给出了软件设计的主流程图。该系统对蜂箱内温度变化规律的研究具有重要的现实意义。     

Performance Analysis of Multiuser Diversity in MIMO Systems with Antenna Selection

In this paper, a framework is presented to analyze the performance of multiuser diversity (MUD) in multiuser point-to-multipoint (PMP) MIMO systems with antenna selection. Based on this framework, the tight closed-form expressions of outage capacity and average symbol error rate are derived for the multiuser transmit antenna selection with maximal-ratio combining (TAS/MRC) system, by which we show how and with what characteristics antenna selection gains, MIMO antenna configurations and fading gains impact on the system performance, with an emphasis on the study of multiuser diversity influence. From both theoretical and simulation results, our study shows that in multiuser PMP TAS/MRC systems an diversity order equals to the product of the number of transmit antennas, number of receive antennas and number of users can be achieved; what's more, users plays a key role in the system performance and can be viewed as equivalent 'virtual" transmit antennas, which is the source of the multiuser diversity inherent exists in the multiuser system. This kind of diversity can be efficiently extracted in the design of multiantenna systems.