The Heterogeneous Growth of P(3MeTh)--An Ellipsometric Study

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">Successive thicker P(3MeTh) layers are analysed by ex situ conventional and imaging ellipsometry. Thin films display a smooth surface, are compact and homogeneous while for a growth charge above 20 mC cm(-2) the polymer structure modifies to a still uniform but less dense layer. A two-layer model is used and a mathematical procedure is developed to obtain, simultaneously, from the experimental ellipsometric parameters, Delta and Psi, the thickness and the complex refractive index of P(3MeTh) films grown up to 80 mC cm(-2). Thicker polymer layers are disordered and present a high degree of surface roughness. span>

配液结晶法制备溶菌酶蛋白质晶体的生长机理研究

采用配液结晶法制取了溶菌酶蛋白质晶体,使用动态光散射测量了溶液中聚集体的颗粒度几率分布;使用Zeiss显微镜测定了溶菌酶(110)晶面的生长速度.实验表明:随着蛋白质和NaCl浓度的增加,溶液中聚集体的颗粒尺寸也相应增加.随着反应时间的增加,溶菌酶分子在溶液中的聚集反应,逐渐达到平衡;在蛋白质和NaCl浓度较高时,溶菌酶晶体的(110)面生长较快,而在蛋白质和NaCl浓度较低时,该晶面生长较慢.基于二维成核生长机理,从晶体生长动力学理论方程出发,计算了二维成核的形成能a=4.01×10-8J?cm-2.

Weibull modulus for diverse strength due to sample-specificity

By sample specificity it is meant that specimens with the same nominal material parameters and tested under the same environmental conditions may exhibit different behavior with diversified strength. Such an effect has been widely observed in the testing of material failure and is usually attributed to the heterogeneity of material at the mesoscopic level. The degree with which mesoscopic heterogeneity affects macroscopic failure is still not clear. Recently, the problem has been examined by making use of statistical ensemble evolution of dynamical system and the mesoscopic stress re-distribution model (SRD). Sample specificity was observed for non-global mean stress field models, such as the duster mean field model, stress concentration at tip of microdamage, etc. Certain heterogeneity of microdamage could be sensitive to particular SRD leading to domino type of coalescence. Such an effect could start from the microdamage heterogeneity and then be magnified to other scale levels. This trans-scale sensitivity is the origin of sample specificity. The sample specificity leads to a failure probability Phi (N) with a transitional region 0 < (N) < 1, so that globally stable and catastrophic modes could co-exist. It is found that the scatter in strength can fit the Weibull distribution very well. Hence, the Weibull modulus is indicative of sample specificity. Numerical results obtained from the SRD for different non-global mean stress fields show that Weibull modulus increases with increasing sample span and influence region of microdamage.

Viscosity, Surface Tension, and Atomization of Water-Methanol and Diesel Emulsions

This article is the result of experimental studies of the rheologv, viscosities, surface tensions, and atomization of water-methanol and diesel emulsions. The Span 80 and Tween 60 are employed to make three emulsifying agents, Y01, Y02, and Y03, with viscosity of 1.32-1.5 Pa s and HLB values of 5.36, 4.83, and 4.51, respectively. In the water-in-oil emulsions, the aqueous phase is between 10% and 50%; the agent concentration added is 0.8-8.0%. The viscosity of the emulsions is 0.003-0.02 Pa s, and the surface tens ion is 0.04-0.1 N/m. The types and concentrations of agents significantly influence the viscosity of the emulsions, and the higher concentration of the aqueous phase (<50%) in creases the viscosities of the emulsions, especially for higher agent concentration. Interfacial membrane and HLB values of the agents can explain all these phenomena. Higher aqueous phase concentration and agent viscosity results in larger Sauter mean diameter.

扩散处理热浸镀铝钢高温抗氧化行为的研究

Modeling and Simulation of Liquid Pulsed Particulate Fluidized Beds

Pulsed fluidization is of considerable interest in process engineering for improving fluidization quality. Quantitative understanding of the pulsed two-phase flow behaviors is very important for proper design and optimum operation of such contactors. The

微米尺度结构最大抗扭强度的在线测试和研究

<span style="color: rgb(0, 0, 0); font-family: verdana, Arial, Helvetica, sans-serif; font-size: 13px;">提出了一种新型的测试结构，对面积为微米量级下键合的最大抗扭强度进行了测试) 实验设计一系列的单晶硅悬臂梁结构测试键合面积在微米量级时的最大剪切力，键合面为常用的矩形其边长从*!+ 到!#$!+，并根据实际移动距离计算得出的最大剪切力) 并实验实际得出最大剪切扭矩和相应的键合面积的曲线，以及最大扭转剪切破坏应力与悬臂梁加载距离的关系，并针对*$!+, *$!+ 的矩形键合结构进行了加载和位移的重复性实验测量，两次测量结果符合较好) 微电子机械系统（+-./0121.3/0+1.456-.52 78731+，9:9;）器件的设计人员可以根据结论曲线，针对所需的抗扭强度设计相应的键合面积，为9:9; 器件工艺的在线定量测试与设计提供参考)span>

Low-Dimensional Dynamical Systems for a Wake-Type Shear Flow with Vortex Dislocations

Low-dimensional systems are constructed to investigate dynamics of vortex dislocations in a wake-type shear flow. High-resolution direct numerical simulations are employed to obtain flow snapshots from which the most energetic modes are extracted using proper orthogonal decomposition (POD). The first 10 modes are classified into two groups. One represents the general characteristics of two-dimensional wake-type shear flow, and the other is related to the three-dimensional properties or non-uniform characteristics along the span. Vortex dislocations are generated by these two kinds of coherent structures. The results from the first 20 three-dimensional POD modes show that the low- dimensional systems have captured the basic properties of the wake-type shear flow with vortex dislocation, such as two incommensurable frequencies and their beat frequency.

Energy Conversion in Shape Memory Alloy Heat Engine Part I: Theory

<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify">Shape Memory Alloy (SMA) can be easily deformed to a new shape by applying a small external load at low temperature, and then recovers its original configuration upon heating. This unique shape memory phenomenon has inspired many novel designs. SMA based heat engine is one among them. SMA heat engine is an environment-friendly alternative to extract mechanical energy from low-grade energies, for instance, warm wastewater, geothermal energy, solar thermal energy, etc. The aim of this paper is to present an applicable theoretical model for simulation of SMA-based heat engines. First, a micro-mechanical constitutive model is derived for SMAs. The volume fractions of austenite and martensite variants are chosen as internal variables to describe the evolution of microstructure in SMA upon phase transition. Subsequently, the energy equation is derived based on the first thermodynamic law and the previous SMA model. From Fourier’s law of heat conduction and Newton’s law of cooling, both differential and integral forms of energy conversion equation are obtained.span>

重力对异向聚集过程影响的探讨

自90年代初,分散体系聚集过程的微重力研究开始受到重视,并有一系列论文发表[1－4].Folkersma[3,4]等人在最近发表的文章中,公布了他们的最新研究结果.在探空火箭实现的微重力条件下,他们发现聚集速率要比地面实验快11倍多.为了解释这一现象,他们把重力的影响分为两部分,即沉降和自然对流.用密度匹配法,检验了在无沉降时的聚集过程.得到的结果是,聚集速率在无重力沉降影响时会比有沉降时快2.7倍.即便如此,微重力实验的聚集速率仍高出4.2倍.他们推断,这一巨大差异是由在地面上无法避免的自然对流造成的.

Deformation behavior and microstructure effect in 2124Al/SiCp composite

<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify">Dynamic compression tests were performed by means of a Split Hopkinson Pressure Bar (SHPB). Test materials were 2124Al alloys reinforced with 17% volume fraction of 3, 13 and 37 μm SiC particles, respectively. Under strain rate ε = 2100 l/s, SiC particles have a strong effect on σspan>_0.2<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify"> of the composites and the σspan>_0.2<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify"> increases with different SiC particle size in the following order: 2124Al-alloy → 124Al/SiCspan>_p<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify"> (37 μm) → 2124Al/SiCspan>_p<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify"> (13 μm) → 2124Al/SiCspan>_p<span style="color: #403838; font-family: Arial, Helvetica, sans-serif; font-size: 13px; line-height: 19px; text-align: justify"> (3 μm), and the strain hardening of the composites depends mainly on the strain hardening of matrix, 2124A1 alloy. The results of dimensional analysis present that the flow stress of these composites not only depends on the property of reinforcement and matrix but also relates to the microstructure scale, matrix grain size, reinforcement size, the distance between reinforcements and dislocations in matrix. The normalized flow stress here is a function of inverse power of the edge-edge particle spacing, dislocation density and matrix grain size. Close-up observation shows that, in the composite containing SiC particles (3 μm), localized deformation formed readily comparing with other materials under the same loading condition. Microscopic observations indicate that different plastic flow patterns occur within the matrix due to the presence of hard particles with different sizes.span>

饱和砂土中桶形基础承载力的实验研究

<span>桶形基础是近年开发的一种新型的可广泛应用于海洋工程结构的基础形式。由于多种优越性而受到各国石油部门的重视,并引起许多研究人员的关注。通过在饱和砂中的单桶和四桶基础模型实验,研究了桶形基础的静承载特性。分别进行了垂直方向和水平方向的加载实验,其中,四桶基础水平方向加载又分为沿四桶中心构成的正方形的平行边方向和对角线方向施加,得到了载荷位移曲线,对单桶和四桶基础承载力特性,以及加载方向和速率的影响进行了分析和比较。 span>更多还原

Saturated duration of rectangular pressure pulse applied to rectangular plates with finite-deflections

<span style="color: #4b4942; font-family: Arial, Verdana, Helvetica, sans-serif; line-height: 18px">The inequities in health care and housing access experienced by low-income women in the United States are a continuing concern. This article addresses the interrelationships between housing and health as experienced by low-income clients so that health care practitioners can begin to build active and effective health-promoting partnerships with clients, their families, and their communities. A case study is presented that describes the actual experience of a woman living in a low-income housing development and its effect on her health and access to health care. The importance of the role of midwives in addressing the health care and advocacy needs of women in substandard housing is highlighted.span>

Effects of physical parameter range on dimensionless variable sensitivity in water flooding reservoirs

<span style="color: rgb(51, 51, 51); font-family: arial, helvetica, sans-serif; font-size: 13px; line-height: 22px; background-color: rgb(248, 248, 248);">The similarity criterion for water flooding reservoir flows is concerned with in the present paper. When finding out all the dimensionless variables governing this kind of flow, their physical meanings are subsequently elucidated. Then, a numerical approach of sensitivity analysis is adopted to quantify their corresponding dominance degree among the similarity parameters. In this way, we may finally identify major scaling law in different parameter range and demonstrate the respective effects of viscosity, permeability and injection rate.span>

解不可压缩流体力学问题的降阶法 Ⅳ.三维Navier—Stokes方程

在本系列文章里,我们提出一种新的解不可压缩流体力学问题的有限元方法——降阶法。实现这种算法的关键是给出零散度空间V~h的一组简单基函数。求速度时,运动方程试函数空间取为V~h解函数空间也取V~h。压力项自动消掉。从而可先求出速度的近似解。之后再求压力解。 本文对于一大类数值求解三维k连通区域Ω上的Navier—Stokes方程(简记为N—S方程)边值问题的一阶有限元格式给出零散度空间V~h的一组简单基函数。与二维问题不同的是,直接给出的“基函数”线性相关。必须从中去掉一部分(对应于某“树”的)函数才能使之成为一组线性无关的基。