Fine-tuned,molecular-composite,organosilica membranes for highly efficient propylene/propane separation via suitable pore size

Fine-tuned, molecular-composite, organosilica membranes were fabricated via the co-condensation of organosilica precursors bis(triethoxysilyl)acetylene (BTESA) and bis(triethoxysilyl)benzene (BTESB). Fourier transform infrared and UV–vis spectra confirmed the co-condensation behaviors of BTESA and BTESB. The evolution of the network structure indicated that the incorporated BTESB decreased the membrane pore size, which was determined by a modified gas translation model according to the steric effect of the phenyl groups. The incorporation of BTESB to BTESA finely tuned the membrane structure and endowed the resultant composite membrane with improved separation properties. The BTESAB 9:1 membrane (molar ratio of BTESA/BTESB was 9:1) exhibited high C₃H₆ permeance at 4.5 × 10⁻⁸ mol m⁻² s⁻¹ Pa⁻¹ and a C₃H₆/C₃H₈ permeance ratio of 33 at 50°C. One of the most important developments of this study involved clearly defining the relationship between membrane pore size and C₃H₆/C₃H₈ separation performance for organosilica membranes in single and binary separation systems.     

一个有效的圆片规模布局算法

本文提出了一个圆片规模布局算法，它是国外一个相应算法的改进形式，区别在于利用力定向布局法的方式不同。在相对位置阶段，该算法利用布局的层次特性将需确定所有电路元件相对位置的问题缩减至仅需确定宏电路元件相对位置的问题；在实际位置阶段，采用分治策略和取消前阶段层次划分的方式回避了需确定任意元实际位置的问题．其时间复杂度远低于国外相应算法．     

媒体服务中流式拷贝性能分析

随着网络带宽的进一步提高,视频点播的瓶颈基本卡在视频服务器端。文章提供的服务器端的流式拷贝,能进一步提高整个系统的服务能力。文章对流式拷贝的过程进行描述,对其中的数学模型进行分析,并与没有流式拷贝的系统进行比较分析。     

容错磁盘阵列的性能模型

本文以排队论为工具，建立了容错磁盘阵列的Ｍ／Ｇ／１排队模型，并在此基础上分析了ＲＡＩＤ的平均响应时间，稳定数据传输率等重要性能指标；比较了同步和异步ＲＡＩＤ的性能差异，最后提出了以吞吐率作为衡量ＲＡＩＤ性能的综合指标，并给出了确定最大吞吐率的定量。     

渣对钢液温度的影响

开发了渣表面散热模型，定量分析了渣层内温度变化规律，以及表面散热情况，比较了模型计算结果与大冶钢厂现场实测值，指出保证５０ｍｍ的渣层厚度有利于减少钢液温度损失，开发的模型可作为钢液温度控制的一部分指导现场生产。     

Determination of the in situ forces and force distribution within the human anterior cruciate ligament

The in situ forces and their distribution within the human anterior cruciate ligament (ACL) can clarify this ligament's role in the knee and help to resolve controversies regarding surgical treatment of ACL deficiency. We used a universal force-moment sensor (UFS) to determine the magnitude, direction, and point of application of the in situ forces in the ACL in intact human cadaveric knees. Unlike previous studies, this approach does not require surgical intervention, the attachment of mechanical devices to or near the ACL, or a priori assumptions about the direction of in situ force. Anterior tibial loads were applied to intact knees, which were limited to 1 degree of freedom at 30 degrees flexion. The in situ forces developed in the ACL were lower than the applied force for loads under 80 N, but larger for applied loads of more than 80 N. The direction of the force vector corresponded to that of the anteromedial (AM) portion of the ACL insertion on the tibial plateau. The point of force application was located in the posterior section of the anteromedial portion of the tibial insertion site. The anterior and posterior aspects of the anteromedial portion of the ACL supported 25% and 70% of the in situ force, respectively, with the remainder carried by the posterolateral portion. We believe that the data obtained with this new UFS methodology improves our understanding of the role of the ACL in knee function, and that this methodology can be easily extended to study the function of other ligaments.     

低组配焊接接头的强度

本文对低组配焊接接头的机理和接头性能等两个方面进行了分析研究.低组配焊接接头静拉伸的力学性能,受焊缝金属的相对厚度所影响,随着相对厚度的减小,接头的拉伸强度由焊缝金属的拉伸强度增至基本金属的拉伸强度.接头强度还随低组配焊接接头的板宽改变而变化,板宽增大,接头拉伸强度增加,直至板宽大于五倍板厚时为止.故低组配焊接接头拉伸强度以含有相对厚度和焊缝金属对基本金属的强度比的公式所计算。     

Radical polymerization of methyl methacrylate with methyl 2,2-dimethyl-3,3-diphenyl-3-cyanopropionate as a thermal iniferter

Summary To clarify the mechanism of living radical polymerization of methyl methacrylate (MMA) with tetraphenylsuccinodinitrile (TPSN) as a thermal iniferter, a model compound for the end group of the poly(MMA) produced, methyl 2,2-dimethyl-3,3-diphenyl-3-cyanopropionate (2), was synthesized and found to initiate a living radical polymerization of MMA, indicating that the hexa-substituted C-C bond in 2 dissociated into radicals. The poly(MMA) thus obtained further initiated the radical polymerization of styrene (St) to give a block copolymer.     

Dielectric Depression and Dispersion in Electrophoretically Fabricated BaTiO3 Ceramic Films

Dielectric depression and dispersion were observed in BaTiO3 ceramic films fabricated by electrophoretic deposition followed by sintering. The dielectric constants were depressed down to 6800–4600 around the Curie point ( T _C ). The dielectric dispersion occurred above T _C . These dielectric properties are attributable to a surface layer formed during sintering. XRD analysis indicated that the surface layer was a hexagonal-like BaTiO₃ phase. A mixed solvent of acetylacetone and alcohol employed in the present work may have been responsible for the formation of the surface layer.     

Development of high performance,waterborne coatings. Part II: Factors affecting adhesion performance

A new manufacturing process for high performance, waterborne coatings for can coating application was developed, which includes emulsification of an epoxy resin with or without a hardener by incorporation of an acrylic resin. It is possible by this new process to emulsify a variety of resins with minimum effects of the surfactant. (acrylic resin). The effects of surfactant and neutralizer on adhesion performance were studied. It was found that the effects of the acrylic resin amount were relatively small, and that the effects of the neutralizer were significant. It was confirmed that the usage of ammonia or amines with a branched alkyl group is required to achieve balanced dry and wet adhesion.