盖梁施工的几种技术分析

通过对盖梁施工的几种技术的探讨与分析，希望能在不同的施工条件下提供参考。     

水声材料小样品声学性能不同测试方法比较

介绍了水声材料声学性能的3种不同的测试方法，通过对同种样品的性能测试，分析了不同测试方法的优缺点。结果表明，与行波法相比，脉冲法和驻波法测试可靠性较高。      

油气储运中废气污染与回收的研究

油品蒸发给从石油开采到成品油使用整个过程带来隐患，环境中油蒸气达到一定浓度易引发火灾、环境污染。油品蒸发还会造成大量油品浪费，并且因油品中轻组分的蒸发，使油品质量下降。本文分析了油品储运过程中蒸发损耗产生的机理，介绍了吸收法、吸附法、冷凝法、膜分离法和各种组合集成法的可行性方案，探讨了各种油气回收技术的优缺点和适用范围。     

古代的测谎法

奥地利的“犯罪侦察学之父”哥洛斯博士说 :犯罪侦察的本质就是搜索真实 ,尽管这些方法在今天看来有些荒唐。沸水法 :这种方法带有浓重的封建迷信色彩。让小偷把手指伸进滚油或开水时 ,如果手指烫坏了 ,就说明他说的是谎话。嚼米审判 :１７世纪的测谎方法带有了一些生理科学色彩。印度人发现说谎的人总是嘴发干 ,因而发明了东方国家普遍使用的“嚼米审判” ,让嫌疑人每个人放一把炒米在嘴里 ,嚼两下吐出来 ,说谎者由于唾液分泌少 ,吐出的米明显比诚实者少。圣猴法 :这种测谎方法开始利用心理学。传说印度有一种圣猴 ,说谎者摸它的尾巴它就会…     

非破坏性试验方法的应用与比较

非破坏性试验方法已广泛应用在焊接质量检测工作中，本文编辑了一些国外资料，以供参考。     

石油库几种常用油气回收技术比较

近年来，随着对环保和节能越来越重视，油气回收系统在油库、加油站得到推广。因为油气回收设备在我国推广较晚，不同的油气回收装置往往采用不同的回收技术。国内现有回收装置的工作原理、结构、价格、适用环境场所及油气回收效果也相差很大。如何投入有限的资金达到较好的回收效果实现更好的环境保护和较大的经济效益对几种不同回收技术的了解更为必要。本文就近年来国内常用的吸附法、吸收法、冷凝法和膜分离法几种油气回收技术进行对比分析。     

基于磁性法的钢中残余奥氏体含量测定方法与装置

阐述了磁性法测定钢中残余奥氏体含量的原理和方法,并研制了一种基于磁性法的钢中残余奥氏体含量测定装置。该测定装置可以实现换向法、甩脱法和动态法等3种残余奥氏体含量测定方法,其中换向法和甩脱法以不同方式静态测定残余奥氏体含量,动态法能够在试件拉伸过程中连续、快速地动态测定残余奥氏体含量与应变的对应关系。该测定装置以LabVIEW为平台,构成了虚拟仪器系统,对数据进行采集、分析和处理,实现了可视化操作、自动测量、曲线显示和数据保存等功能。使用该装置采用3种方法分别对M50NiL轴承钢中的残余奥氏体含量进行了测定,试验结果表明该测定装置能够精确地测定钢中的残余奥氏体含量。     

土方量的计算方法和精度分析

本文主要介绍了土方量的计算方法和基本原理以及精度的分析比较,并从理论上探讨了它们的适用范围。     

超微粉制备技术的现状与展望

超微粉具有多种优良的特性，是重要的高科技结构和功能材料，在许多领域里日益显示出广阔的应用前景。本文对国内外各种超微粉制备技术进行了科学的分类，并介绍了各种方法的原理和优缺点，同时展望了今后超微粉制备技术的发展方向。     

CdS纳米颗粒的合成方法研究及比较

CdS纳米颗粒在太阳能转化、非线性光学、光电子化学电池和光催化等方面具有广泛的应用,因此其合成方法的研究近年来受到人们的青睐.按照反应物的状态,将纳米硫化镉的制备方法分为固相法、液相法和气相法.本文详细介绍了各种制备方法,分析比较了它们的优点和缺点.     

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.     

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.     

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.     

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.     

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.     

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.