基于MC68360视频压缩系统的设计分析

提出了一种新的嵌入式视音频压缩/解压缩系统的设计方案,该方案采用MC68360作为主控芯片,VW2010作为解压缩核心芯片.实验结果证明该方案具有可靠性高、抗干扰能力强、功耗小、性价比高等优点,可以很好地实现MPEG4标准的视音频压缩/解压缩.     

公理化设计与DFA集成的产品信息模型

在公理化设计理论的基础上,讨论了产品设计过程中功能要求的分解以及从功能域向结构域的曲折映射过程;建立了产品功能一结构层次模型和面向装配设计的产品信息模型．该产品信息模型不仅能够描述产品的层次结构信息,而且能够描述零部件之间的装配关系信息,能够实现CAD／CAE／CAPP/CAM的信息集成,为产品并行开发过程的信息集成打下良好的基础．以发动机减速器为例,对产品的功能树、结构树以及装配模型和装配关联矩阵的形成进行了说明。     

Reusable and durable electrostatic air filter based on hybrid metallized microfibers decorated with metal-organic-framework nanocrystals

As global air pollution becomes increasingly severe,various types of fibrous filters have been devel-oped to improve air filter performance.However,fibrous filters have limitations such as high packing density that generally causes high-pressure drop and ultimately deterioration in the filtration effi-ciency.High-pressure particulate matter precipitators are limited in terms of scope for commercialization because they require high voltage supplies and ozone generators.In this study,we develop fibrous fil-ters with enhanced durability and improved performance using metallized microfibers decorated with metal-organic-framework(MOF)nanocrystals.Not only does the efficiency of the developed filters remain at or above 97％for 0.50-1.5 μm PMs but the durability also significantly increases.In addi-tion,using the water purification ability of the MOF,we explore the dye degradation effect of the hybrid microfibers by immersing them into Rhodamine B aqueous solution.In such an experiment the Rho-damine B aqueous solution is completely purified by the presence of the hybrid microfibers under the UV irradiation.     

Tuning effect of silicon substitution on magnetic and high frequency electromagnetic properties of R2Fe17 and their composites

In this work, we report the tuning effect of the Si substitution on the magnetic and high frequency electromagnetic properties of R₂Fe₁₇ compounds and their paraffin composites. It is found that the introduction of Si can remarkably improve the magnetic and electromagnetic properties of the R₂Fe₁₇ compounds, making the R₂Fe_17–xSi_x-paraffin composites excellent microwave absorption materials (MAMs). By introducing the Si element, their saturation magnetizations decrease slightly, while much higher Curie temperatures are obtained. Furthermore, better impedance match is reached due to the decrease of the high-frequency permittivity ε′ by about 40%–50%, which finally enhances the performance of the microwave absorption. The peak frequency (f_RL) of the reflection loss (RL) curve moves toward high frequency domain and the qualified bandwidth (QB, RL ≤ ?10 dB) increases remarkably. The maximum QB of 3.3 GHz (12.0–15.3 GHz) is obtained for the Sm_1.5Y_0.5Fe₁₅Si₂-paraffin composite (d = 1.0 mm) and the maximum RL of ?53.6 dB is achieved for Nd₂Fe₁₅Si₂-paraffin composite (d = 2.2 mm), both surpassing most of the reported MAMs. Additionally, a distinguished dielectric microwave absorption peak is observed, which further increases the QB in these composites.     

Effect of preparation method on physicochemical properties and catalytic performances of LaCoO_3 perovskite for CO oxidation

Perovskite oxides LaCoO_3 prepared by templating, co-precipitation and sol-gel method with different complexants were systematically characterized and its catalytic performances for CO oxidation were investigated. The samples were characterized by X-ray diffraction, thermogravimetry analysis and differential scanning calorimetry, N_2 physisorption, transmission electron microscopy, temperature program reduction of hydrogen, temperature program desorption of oxygen and X-ray photoelectron spectroscopy measurement, results of which show that the properties of LaCoO_3, such as surface morphology, surface area, surface compositions, redox capability, oxygen vacancy, as well as the calcination temperature and formation mechanism, depend intimately on the preparation method. Catalytic tests indicate that the sample prepared by carbon templating method shows the best activity for CO oxidation, with full CO conversion obtained at 135 ℃. In particular, the catalyst can be activated and significant increase of activity can be obtained with the increase of reaction time. The cyclic and longterm stability of catalysts were discussed and compared.     

高强韧性液压支柱无缝钢管的研制开发

目前国内开采煤炭用液压支柱及矿用支架普遍采用27SiMn无缝钢管,随着煤炭工业的发展以及煤炭生产对安全性的更高要求,该钢种无缝钢管管体在大生产中热处理后的力学性能已达不到高强度高韧性的要求。通过优化钢管的化学成分,研究生产工艺路线及冶炼工艺、热处理工艺,成功开发出高强韧性液压支柱用无缝钢管并投入批量生产。使用结果表明,该产品的强韧性、焊接性能等满足用户要求。     

隧道掘进机快速拆装举撑液压系统仿真

针对隧道掘进机（TBM）在施工现场因空间限制无法满足调试所需较大空地的问题,设计一种用于TBM洞内快速拆装变位的举撑液压系统。该液压系统由4组顶升单元构成,通过4组顶升单元同步运动实现TBM的起吊和举撑;液压顶升单元由4根四级液压缸、液压控制系统、激光位移传感器和机架构成。基于AMESim建立四级液压缸、变量泵和比例节流阀以及整个顶升单元的液压仿真模型,通过仿真分析负载下液压缸运动的速度、位移和压力曲线。结果表明：改变比例节流阀的输入信号可以实现四级液压缸速度的变化;泵出口压力可由比例溢流阀调整;在2.5×105N的额定负载下,四级缸的换级工作腔压力逐级上升;随着换级,活塞杆伸出速度逐渐上升。与理论计算对比显示,建立的TBM洞内快速拆装液压系统顶升单元的AMESim仿真结果和理论值基本吻合。     

全球蛋氨酸市场现状分析

目前全球蛋氨酸市场由少数几家公司控制 ,其中Novus、Degussa、Adiesso公司分别占有 3 4%、3 0 %和 2 8%的市场份额 ,国内迄今尚未有一套规模型生产装置。而亚洲地区蛋氨酸供应紧张 ,中国作为世界第二大饲料生产国 ,对蛋氨酸的需求更高 ,目前我国主要依靠进口解决需求问题 ,2 0 0 1～ 2 0 0 3年每年进口量均在 5万t/a以上。     

黄原胶类破乳剂的合成及其破乳特性

在温度120～135℃、压力0．35～0．4MPa条件下,以相对分子质量大、活泼氢多、具有分支结构的黄原胶作起始剂,与环氧乙烷、环氧丙烷加成,合成出具有分支结构的黄原胶类破乳剂(XE型和XP型),并筛选出性能较好的3种破乳剂XEl89、XP180和XP120;当把XE189、XP180与常规破乳剂F311l复配时能够满足华北五厂原油乳状液破乳脱水的要求,复配体系的脱水速率比油田现场用剂提高1．5～2．0倍,脱水效果优于油田现场用剂。当把XE189、XP120破乳剂与少量的糖脂类生物表面活性剂(200：15)复配后,能够成倍提高巴西海上油田原油乳状液的破乳脱水速率和最终脱水体积,黄原胶类破乳剂与该种糖脂类生物表面活性剂之间存在协同作用。     

基于科学发展观的区域空间管治策略探讨——以广州从化市为例

由于缺乏深入的分区政策设计与充实的政策内涵,现行管治政策无法完全适应从化市自上而下和自下而上的双重发展诉求。为了实现经济社会发展与资源生态环境保护的双赢,从化市需要以科学发展观为指导,树立区域经济协调发展观念,强调经济发展对可持续发展的重要性,完善经济发展衡量标准和政绩考核机制,以此指导区域空间管治政策的编制与实施。