Hydrothermal synthesis of ultrathin Bi2MO6 (M=W,Mo) nanoplates as new host substances for red-emitting europium ion

Ultrathin Bi2MO6 (M?W, Mo) nanoplates were synthesized by a simple hydrothermal method. SEM, EDS and XRD were used to investigate the morphologies and compositions of the samples from BiONO3 nanoplates along with some nanoparticles, to precursory Bi2WO6 nanoplates and Bi2MoO6 nanoparticles, and to final Bi2MO6 nanoplates. The possible formation mechanism of products was proposed. The experimental results exhibited that Bi2MO6 nanoplates had stronger light adsorption in ultraviolet–visible range. Bi2MO6 nanoplates were useful host for rare earth ions, Eu3twas successfully doped in Bi2MO6 nanoplates and an energy efficiently transferred from Bi3t to Eu3t, displaying intense red color under ultraviolet (UV) light excitation. The morphologies of products kept constant after doping. It is suggested that Bi2MO6:Eu nanoplates have promising application in fluorescent mark.     

A distributed clustering algorithm for wireless sensor networks

In the paper, we consider a network of energy constrained sensors deployed over a region. Each sensor node in such a network is systematically gathering and transmitting sensed data to a base station （via clusterhead） for further processing. The key problem focuses on how to reduce the power consumption of wireless microsensor networks. The core includes the energy efficiency of clusterheads and that of cluster members. We first extend low-energy adaptive clustering hierarchy （LEACH）＇s stochastic clusterhead selection algorithm by a factor with distance-based deterministic component （LEACH-D） to reduce energy consumption for energy efficiency of clusterhead. And the cost function is proposed so that it balances the energy consumption of nodes for energy efficiency of cluster member. Simulation results show that our modified scheme can extend the network life around up to 40% before first node dies. Through both theoretical analysis and numerical results, it is shown that the proposed algorithm achieves better performance than the existing representative methods.     

几种Bernstein算子、Meyer－Konig－Zeller算子及其性质

本文对单纯形和单位正方形上的两种二元算子进行了推广，同时又引进了二元Ｍｅｖｅｒ－Ｋｏｎｉｇ－Ｚｅｌｌｅｒ型算子及其推广形式，关讨论了它们的性质。     

SBR处理水性油墨废水的研究

采用二级序列间歇式活性物理法(SBR)串联工艺,对预处理后的水性油墨废水进行了试验研究,结果表明:当进水化学耗氧量(COD)为2 000～4 000mg/L,色度为200～400倍,pH为6.5～7.5,温度为25℃、曝气时间为8h、物理沉降比(SV)为35%的条件下,出水COD去除率保持在93%以上,色度去除率达80%以上。出水色度和COD浓度分别达到国标(GB 4297-92)Ⅰ、Ⅱ级排放标准。     

一个基于TMS320C5402DSP应用系统的设计

介绍一种基于TMS320C5402 DSP芯片的压缩语音录放系统的软硬件设计方法.该系统通过对语音进行压缩以实现高效率数字录音,可应用于电话留言、语声应答等场合.其中电话留言是本系统的一个典型应用.     

PCR-DGGE法分析温度对A~2/O系统硝化茵群结构的影响

研究了温度对A~2/O装置中硝化细菌群落结构的影响.旨在为工艺改进及优化调控提供依据.从A~2/O装置的泥水混合液中采集微生物样品并提取微生物总DNA,使用特定引物对从总DNA中扩增出目标DNA片段,然后对扩增的DNA片段进行DGGE,并对凝胶进行染色和条带统计分析,通过聚类分析构建不同温度下硝化菌群间的相似性关系.结果表明,AOB菌在温度>25℃时,群落结构比较稳定.此时NH_4~+-N去除率高达95%以上;Nitrobacter菌在温度>20℃时,群落结构则比较稳定,NH4+ -N去除率亦可达95%以上;Nitrospira群落结构发生变化较大,相比较而言,15～20℃时最稳定,NH_4~+-N去除率在75%～95%之间.     

竹亚科新分类群

本文描述了竹亚科少穗竹属1新种、1新变种和1新组合。     

兰州市区低空大气温度层结构特征及其与空气污染的关系

利用1988－1992年兰州市气象站逐日08h（北京时,下同）常规气象探空观测资料及同期兰州市环境监测站空气污染物浓度监测资料,统计分析了市区低空大气温度层结变化特征及其与3种主要空气污染物（SO2,CO和NOx）浓度之间的关系,结果表明：兰州市区低空大气温度层结全年以弱稳定为主,一年四季皆有逆温层存在;在冬季,逆温层性频率最高（95．8％）,贴地逆温层厚度最厚（平均740m）、强度最强（平均0．53℃／100m）,脱地逆温层底相对高度最低（平均935m）;同时,贴地大气层结温度递减度与空气污染物浓度呈显著反相关,由此表明,兰州市区低空大气温度层结状况是影响该市空气污染程度的重要因素之一。     

基于CAD的产品装配特征多层映射数学模型

用数学方法描述了产品设计特征和装配特征信息,应用集合论在特征信息描述的基础上,探讨了特征映射机理,通过多层特征映射,建立了产品从设计域以装配城的特征映射数学模型,为并行工程中多域特征映射理论的研究奠定了基础。     

汽车后桥强化程序载荷谱

符合实际路况的室内强化疲劳试验,可以加快汽车结构部件的试验进程.本研究通过对汽车后桥垂直载荷的分析,提出了按路面强化的试验方法.在编制程序载荷谱的基础上,对后桥壳体进行了强化疲劳试验.