铝型材挤压模CAD/CAE/CAM系统开发与应用

基于对型材挤压特点的详尽分析,提出了铝型材挤压模CAd/CAE/CAM系统功能模型并确定了基于UG和AMSYS平台的系统集成方案,对关键软件模块进行二次开发,在此基础上对平模挤压折角、槽型材和分流组合模挤压扁管型材进行了分析.     

PXI总线四通道D/A模块设计

本文介绍了PXI总线D/A模块的设计.该模块具有四通道可程控的直流电压和直流电流的选择输出.根据PXI总线规范,本模块采用PCI总线专用接口芯片9030和EPLD技术来完成PXI总线接口电路设计以及模块功能电路的具体实施方案.     

基于B/S与C/S模式教务管理系统的模块设计

根据我国高校教务管理的现状,结合我院实际需求,分析教务管理系统采用B/S与C/S混合模式的原因及其特点,对系统所涉及的相关模块功能进行划分和设计,给出教务管理系统的数据库存储模式、概念模型和详细库表设计。     

CAD/CAPP/MRPⅡ/GT信息集成的初步研究

实现CIMS的关键技术之一是动态信息集成。奉文论述了一个CIMS雏形系统中CAD/CAPP/MRPⅡ/GT之间的信息集成技术及其实现方法。提出了在CAD系统中通过建立与工艺设计工步内容相匹配的、基于设计基本特征和工艺基本特征的特征建模技术及处理程序来实现CAD/CAPP之间信息共享的方法;论述了CAPP系坑通过与MRPⅡ系统中工艺路线管理模块之间实时信息传递来实现并行式CAPP设计的步骤;提出了在GT与MRPⅡ之间寻找一个最佳结合体——工装族制造管理系统等新思想。论文对各子系统也做了简要描述。     

基于PRO/ENGINEER的参数化建模与实践

利用 PRO/E 参数化建模的特点,介绍了在 PRO/E 中通过二次开发快速建模的方法;以齿轮建模为例,采用参数化方法建立齿轮模型,开发了齿轮快速建模的模块,并以此模块建立了某行星式变速箱模型。     

集成相变储热材料的光伏/热复合系统性能分析

将相变材料(phase change material,PCM)与光伏/热(photovoltaic/thermal,PV/T)模块集成,可通过提高冷却能力改善光伏面板的发电效率,同时利用PCM存储热能并合理利用。在2种集成相变储热材料的PV/T模块设计基础上,采用数值模拟方法进行性能分析,并与传统PV/T装置进行比较。从能量和(火用)2方面对集成系统的整体性能进行分析,并研究冷却工质流量的影响。结果表明,将相变储热材料与PV/T模块集成可显著提高系统的整体性能。其中集成2种相变储热材料的PV/T系统的日总能量效率和总(火用)效率最高,分别为67.65%和12.86%,每日可提供的能量最高可达3 603.2 W·h/m²。随着冷却工质体积流量的增加,总能量效率略有提高,但总(火用)效率显著下降。     

协议分析仪2Mb/s高速信令处理模块

为了满足2 Mb/s高速信令的测试要求，开发了2 Mb/s高速信令协议分析仪信令处理模块。信令处理模块分为硬件系统和软件系统两部分。介绍了开发2 Mb/s高速信令协议分析仪的意义，使用2 Mb/s高速信令链路的优势，信令处理模块的设计原理和功能。介绍嵌入式处理器和实时操作系统的相关内容。     

基于B/S模式的企业标准信息管理系统

本文介绍了标准信息化工作对提高企业核心竞争力的重要作用,提出了基于B/S模式的企业标准信息管理系统的架构方法,并结合所开发的系统实例着重讨论了MVC技术在B/S架构中的应用,介绍了实例系统各模块的主要功能和标准有效性确认模块的创新点,分析了各模块之间的内在联系,证明是一种较为先进和有效的设计模式。     

基于LabWindows/CVI的工程机械振动测试与分析系统

本文介绍了一个利用虚拟仪器技术开发的工程机械振动测试与分析系统.系统以WBK14信号调理模块、WBKS12数据采集模块和计算机为主控平台,利用虚拟仪器开发软件LabWindows/CVI7.0与高级信号分析软件包等,实现对工程机械整机及各部件性能的多功能检测、分析、处理和显示存储,满足对测试过程高精度、自动化、智能化等各项测试要求.     

压力模块作为压力(差压)变送器检定/校准标准的技术参数分析与确定

针对0.5级的压力变送器检定/校准标准建标情况,对照规程要求,对检定/校准标准的测量不确定度进行了估算,并以此为据对检定/校准标准中标准模块的量值、准确度等级和检定量程内标准模块的组合进行了系统分析和探讨。     

Structural and optical properties of AlxOy/Pt/AlxOy multilayer absorber

We report on the microstructure and optical properties of Al_xO_y–Pt–Al_xO_y interference-type multilayer films, deposited by electron beam (e-beam) deposition onto corning 1737 glass, silicon (1 1 1) and copper substrates. The structural properties were investigated by Rutherford backscattering spectrometry, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy. The optical properties were extracted from specular reflection/transmission, diffuse reflectance and emissometer measurements. The stratification of the coatings consists of a semi-transparent middle Pt layer sandwiched between two layers of Al_xO_y. The top and bottom Al_xO_y layers were non-stoichiometric with no crystalline phases present. The Pt layer is in the fcc crystalline phase with a broad size distribution and spheroidal shape in and between the rims of Al_xO_y. The surface roughness of the stack was found to be comparable to the inter-particle distance. The optical calculations confirm a high solar absorptance of ∼0.94 and a low thermal emittance of ∼0.06 for the multilayer stack, which is attributed not only to the optimized nature of the multilayer interference stacks, but also to the specific surface morphology and texture of the coatings. These optical characteristics validate the spectral selectivity of the Al_xO_y–Pt–Al_xO_y interference-type multilayer stack for use in high temperature solar-thermal applications.     

Synthesis of a new perovskite Pb(Li14Nb34)O3

A high-pressure technique was adopted to obtain perovskite-type $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$. A new perovskite $\text{Pb(Li}{}_{\mathrm{<mtext>1</mtext><mtext>4</mtext>}}\text{Nb}{}_{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}\text{)}\text{O}{}_3$ was characterized to have a cubic symmetry with $\text{a}{}_{\mathrm{<mtext>o</mtext>}}\text{= 4.069}\text{A}\text{?}$; Li and Nb ions in the B-site of perovskite lattice may be in a random arrangement.     

Optimization of AlxOy/Pt/AlxOy multilayer spectrally selective coatings for solar-thermal applications

Spectrally selective Al_xO_y/Pt/Al_xO_y multilayer absorber coatings were deposited onto corning 1737 glass, Si (111) and copper substrates using electron beam (e-beam) vacuum evaporator at room temperature. The employment of ellipsometric measurements and optical simulation was proposed as an effective method to optimize and deposit multilayer solar absorber coatings. The optical constants (n and k) measured using spectroscopic ellipsometry, showed that both Al_xO_y layers, which used in the coatings, were dielectric in nature and the Pt layer was semi-transparent. The optimized multilayer coatings exhibited high solar absorptance α ∼ 0.94 ± 0.01 and low thermal emittance ? ∼ 0.06 ± 0.01 at 82 °C. The Rutherford backscattering spectroscopy (RBS) data of Al_xO_y/Pt/Al_xO_y multilayer absorber indicated the Al_xO_y layers present in the coating were nearly stoichiometry. The scanning electron microscope analysis (SEM) result indicated that the average diameter and inter-particles distance of Pt grains were statistically about 146 ± 0.17 nm and 6-10 ± 0.2 nm respectively.     

Bulk crystalline BaPb34Bi14O3: A ceramic superconductor

The preparation conditions of the high T_C ceramic superconductor Ba(Pb,Bi)O₃ is correlated with the superconducting transition. Transition onsets of all materials are similar, but transition widths and transition completeness is strongly dependent on firing temperature. Only materials prepared over a narrow temperature range, resulting in a nearly ideal weight loss, have a complete and narrow transition.     

Electrostriction in Pb (Zn13Nb23)O3

The electrostriction in $\text{Pb (Zn}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Nb}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{)}\text{O}{}_3$ crystals has been investigated using a strain gauge method. In the ferroelectric phase below 140 C, the strain vs the electric field shows a hysteresis, which is ascribed to the effect of ferroelectric domains. A quadratic relation holds between the strain x and the electric polarization P as x = QP² above about 170 C in the paraelectric phase. Values of the electrostrictive Q coefficients are determined from the measurements near 190 C, as Q₁₁ = 1.6·10^?2m⁴/C², Q₁₂ = ?0.86·10^?2m⁴/C², and Q₄₄ = 0.85·10^?2m⁴/C².     

Magnetic,electrical and thermal studies on the V1−xMox02

The monoclinic-to-tetragonal structure transition of oxides V_1?xMo_x0₂ with $\text{0≤}\text{x}\text{≤0.20}$ has been studied by means of DTA, X-ray diffraction, magnetic susceptibility (powder samples) and electrical conductivity (single crystals) measurements within the temperature region 80 K to 400 K. A linear decrease of the transition temperature of 11 K per atom % Mo was observed. The magnetic susceptibility of the low temperature phase was found to be temperature independent paramagnetic for all preparations. Electrical conductivity measurements on the same phase showed crystals with $\text{x}\text{? 0.04}$ to be semiconducting, while a metallic behavior was observed in the region $\text{0.10 ?}\text{x}\text{? 0.14}$.     

n-PbTep+−Pb1−xSnxTe heterojunctions prepared by a modified hot wall technique

$\text{n-PbTe}\text{p}{}^{\mathrm{+}}\text{?}\text{Pb}{}_{\mathrm{1?x}}\text{Sn}{}_{\mathrm{x}}\text{Te}$ heterojunctions with a long wavelength spectral cutoff (λ_c ≈ 6 μm) were prepared using the double-channel hot wall technique. The electrical and photoelectrical properties of the heterojunctions at 77, 197 and 300 K were investigated. Detectors with R_oA equal to 170 Ω cm² and a quantum efficiency of 25–40% were obtained. Reasons for the shift of the long wavelength spectral cutoff of the heterojunctions towards shorter wavelengths are given.     

Reactive plasma deposited SixCyHz films

Si_xC_yH_z films have been prepared at 200°C by reactive plasma deposition from SiH₄ and CH₄ diluted in helium in a tubular reactor. These films have a ratio s (equal to $\text{Si}\text{(}\text{Si+C}\text{))}$ ranging from 0.2 to 0.8, a refractive index ranging from 1.96 to 2.6 and an optical energy band gap in the range 2.7-2.2 eV. The total quantity of hydrogen in the film is 40% when s=0.5. Infrared analysis shows that these films have large fractions of homonuclear bonds and that this material is best described as a polymer. Mass spectrometric measurements of the gaseous products formed in the SiH₄-CH₄-He plasma have been performed and the results are related to the composition of the deposited layers.     

Core-current-enhanced domain-wall pinning in nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon

We have studied the influence of surface fields H/sub p/ (generated by either direct or alternating core current) on soft magnetic properties of amorphous and nanocrystalline Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 15.5/B/sub 7/ ribbon. While in an amorphous ribbon the coercive field H/sub c/ decreases with H/sub p/, in the same optimally annealed ribbon (H/sub c/=1.3 A/m, M/sub m//spl ap/M/sub s/) H/sub c/ increases with H/sub p/ for all the explored types of H/sub p/ (static and dynamic with different phases with respect to that of the magnetizing field H). The unexpected increase of H/sub c/ in nanocrystalline ribbon is associated with the influence of H/sub p/ on the surface and main (inner) domain structure. Here, we develop a model that takes into account this influence and explains the experimental results.     

Interfacial microstructure of NiSix/HfO2/SiOx/Si gate stacks

Integration of NiSi_x based fully silicided metal gates with HfO₂ high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi_x film. Ni content varies near the NiSi/HfO_x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi_x/HfO₂ interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi_x/HfO_x was found higher than that of poly-Si/HfO₂, likely due to compositional non-uniformity of NiSi_x. No intermixing between Hf, Ni and Si beyond interfacial roughness was observed.