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991.
强调了子午投影法的两个特点,即几何元素至回转轴和至水平投影面的距离都不改变。提出以这两个不变量建立直线的子午投影的方程式,也就是确定回转曲面轮廓线的方程式。以二维的平面曲线的方程式代替了三维空间曲面的方程式。文中通过方程式的推导,论证了上述观点,并以此为基础,进一步论述了各种特殊位置直线的子午投影的方程式,以及这些子午投影旋转后所形成的曲面。 相似文献
992.
Kitae?Baek Hyun-Jae?Shin Hyun-Ho?Lee Young-Sun?Jun Ji-Won?YangEmail author 《Korean Journal of Chemical Engineering》2002,19(4):627-631
Electrochemical removal of sodium ion from fermented food composts was analyzed and statistically modeled by response surface
methodology (RSM). Empirical models were developed to describe relationships between the operating variables (operation time,
current density and water contents) and three responses (removal efficiency, energy expenditure and energy efficiency). Statistical
analysis indicated that operation time and current density have significant effect on all responses. Good agreement between
predicted and measured values confirmed the usefulness of the model. The models were verified by additional experimental at
optimum conditions. 相似文献
993.
Sang-Joon?Yoon Min-Soo?Kim Dong-Hoon?ChoiEmail author 《Journal of Mechanical Science and Technology》2002,16(8):1102-1108
In this study, a topological design sensitivity of the air bearing surface (ABS) is suggested by using an adjoint variable
method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible
condition. A residual function of the slider is considered as an equality constraint function, which represents the slider
in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological
parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly
nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings.
An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver
to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model
of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of
FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA
results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing
process. 相似文献
994.
The deposition of perovskite-type oxides thin films [La0.8Sr0.2MnO3 and La1–xSrxCo1–yFeyO3 (0 x 0.4 and 0 y 1)] was investigated using the electrostatic spray deposition (ESD) technique. Lanthanum nitrate, strontium chloride and manganese nitrate, or cobalt nitrate and iron nitrate were dissolved into a mixture of 33 vol% ethanol and 67 vol% butyl carbitol, which was used as precursor solution. The effect of process parameters, such as deposition temperature, deposition time and concentration of precursor solution, on the surface morphology and microstructure of thin films were examined with scanning electron microscope (SEM). The deposited La0.8Sr0.2MnO3 and La1–xSrxCo1–yFeyO3 thin films were amorphous at the used deposition temperature (573K). Subsequently, the samples were heated at 1173 K for 2 h and were studied using X-ray diffraction (XRD). As the result, the crystal structure of the samples transformed to the desired perovskite phase. The chemical analysis of the thin films was investigated using energy dispersion X-ray (EDX) analysis. The observed chemical compositions of the samples were in a fair agreement with the ones of the starting solutions. 相似文献
995.
分析了由 2 .3tGCr1 5高碳铬轴承钢铸锭轧成 1 40mm×1 40mm初轧坯表面纵裂纹的形成原因 ,得到的结果表明 :初轧时由于第一道次孔型内一个方向上压下量过大 ,使轧件高宽比太大而产生该种裂纹。改进初轧工艺后 ,即消除了该种裂纹。 相似文献
996.
生物洁净室的污染控制 总被引:1,自引:0,他引:1
生物洁净室的目的是控制细菌污染。通过对细菌特性、来源及污染途径的分析,确定了全方位、全过程控制的基本思想,即污染源控制,污染传播过程控制和交叉污染控制,通过分析微粒的运动特性,提出了空气途径污染的主要手段是气流流动控制和表面污染控制,最后分析了交叉污染的形成原因及其防治措施。 相似文献
997.
W. D. Henshaw 《Engineering with Computers》2002,18(3):265-273
We are interested in building structured overlap-ping grids for geometries defined by Computer-Aided-Design (CAD) packages.
Geometric information defining the boundary surfaces of a computation domain is often provided in the form of a collection
of possibly hundreds of trimmed patches. The first step in building an overlapping volume grid on such a geometry is to build
overlapping surface grids. A surface grid is typically built using hyperbolic grid generation; starting from a curve on the
surface, a grid is grown by marching over the surface. A given hyperbolic grid will typically cover many of the underlying
CAD surface patches. The fundamental operation needed for building surface grids is that of projecting a point in space onto
the closest point on the CAD surface. We describe a fast and robust algorithm for performing this projection which makes use
of a fairly coarse global triangulation of the CAD geometry. Before the global triangulation is constructed the connectivity
of the model is determined by an edge-matching algorithm which corrects for gaps and overlaps between neighbouring patches.
ID="A1" Correspondence and offprint requests to: Dr. W. D. Henshaw, Center for Applied Scientific Computing, L-661, Lawrence Livermore National Laboratory, Livermore, CA
94551, USA. E-mail: henshaw@llnl.gov 相似文献
998.
999.
Y. Takeda O.A. Plaksin J. Lu K. Kono N. Kishimoto 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):372-376
Optical nonlinearity and dispersion were studied for Cu nanoparticle composite. Negative Cu− ions with 60 keV were applied for implanting into SrTiO3 at a flux of 10 μA/cm2 up to a total fluence of 1 × 1017 ions/cm2. The steady-state optical spectrum of Cu-implanted SrTiO3 showed a surface plasmon resonance resulting from the formation of nanoparticles. Transient transmission and reflection were measured by the pump–probe method with a femtosecond laser system. Optical nonlinearity originated from Cu:SrTiO3 nanoparticle composite and from SrTiO3 matrix overlap, in measured transient spectra. The nonlinear component of Cu:SrTiO3 composite was extracted from the transient spectra with the difference of time response. Nonlinear dielectric coefficient and dispersion around the surface plasmon resonance were derived from extracted transient spectra. The dispersion was compared with a local electric field factor. 相似文献
1000.
三直链烷基苯磺酸钠的合成及其表面活性的研究 总被引:3,自引:3,他引:3
为了研究三直链烷基苯磺酸钠的分子结构与表面活性之间的关系,以对二氯苯为原料,经交叉耦合反应、傅-克酰基化反应、黄鸣龙还原反应、磺化反应以及中和反应等步骤,合成了5种不同烷基链长的三直链烷基苯磺酸钠,产物的收率为45%~53%,用两相滴定法测定产物的纯度均大于99.5%,并用核磁共振氢谱和碳谱对产物进行了结构鉴定。用Wilhelmy-Plate法测定了三直链烷基苯磺酸钠水溶液的表面性质,发现直链烷基苯磺酸钠疏水链碳数增加,临界胶束浓度CMC减小;相同疏水碳原子的化合物,短侧链碳数少的化合物CMC低;长侧链碳数保持不变,两个短侧链碳数由4个增加至8个,临界胶束浓度下的表面张力γcmc由32.44mN/m降低至28.97mN/m;而短侧链碳数保持不变,长侧链碳数由7个增加至11个,γcmc变化不明显。 相似文献