Measurements of single chain form factors by small-angle neutron scattering from polystyrene blends containing high concentrations of labelled molecules

A series of small angle neutron scattering measurements on blends of normal polystyrene (PSH) and labelled (deuterated) polystyrene (PSD) have been made with concentrations of PSD from 5 to 50 mol %. It is shown that the single chain form factor of the polymer in bulk can be obtained from a single concentration measurement for any concentration of labelled molecules, providing the molecular weights of the parent and labelled molecules are the same and the molecular weight distributions are narrow.     

Delay-dependent state estimation for delayed neural networks

In this letter, the delay-dependent state estimation problem for neural networks with time-varying delay is investigated. A delay-dependent criterion is established to estimate the neuron states through available output measurements such that the dynamics of the estimation error is globally exponentially stable. The proposed method is based on the free-weighting matrix approach and is applicable to the case that the derivative of a time-varying delay takes any value. An algorithm is presented to compute the state estimator. Finally, a numerical example is given to demonstrate the effectiveness of this approach and the improvement over existing ones.     

高速往复式内燃机平衡轴低质量设计分析

分析了扇形和偏心圆两种平衡轴设计的要求以及平衡重低质量的设计原则。扇形平衡重半径及宽度应尽量大、夹角应尽量小。偏心圆平衡重的偏心圆半径应尽可能大 ,轴承半径应尽可能小。同样质量的扇形平衡重产生的平衡力比偏心圆平衡重要大。     

印刷质量控制的基本方法(一)综述

无论哪一种印刷品的生产都要经过若干个工艺过程，才能将原稿上的图文信息转移到承印物上。由于印刷技术的飞跃发展，标准化和质量控制成为一个很重要的问题。标准化和质量控制在很大程度上是依靠仪器和控制装置来实现的。科学技术的极大发展，大大地推动了印刷技术的发展，印刷所使用的原材料和工艺得到了很大的改进，逐步实现了标准化，提高并稳定了生产高质量产品的能力。目前我们评价印刷品质量的优劣大致有三种方法：主观评价法、客观评价法和综合评价法。主观评价法，是以原稿为基础对照样张来评价。这里有人为的因素，根据评价人的知…     

国产延迟树脂在腈纶溶剂NaSCN除杂装置的应用

叙述了国产的延迟树脂与进口DOWEX-11-A8树脂在腈纶厂NaSCN回收模拟装置上的比较试验,由试验数据可得出;国产的延迟树脂NVI脱除率性能略优于美国DOWEX-11-A8树脂,并可替代DOWEX-11-A8树脂应用于腈纶厂延迟装置中。     

End-User Computing in a CASE Environment

Computer-aided software engineering (CASE) tools are currently being used by IS professionals rather than by users. No matter how effective these tools may be, however, they will not be able to assist in the reduction of application backlogs without supporting user-driven applications. This article examines characteristics of a CASE environment from the various perspectives of decision support, identifies the advantages and limitations of end-user computing in this environment, and suggests how IS managers can realize the potentials of CASE for user applications.     

A Built-in Self-Test Scheme with Diagnostics Support for Embedded SRAM

In this paper we propose a novel built-in self-test (BIST) design for embedded SRAM cores. Our contribution includes a compact and efficient BIST circuit with diagnosis support and an automatic diagnostic system. The diagnosis module of our BIST circuit can capture the error syndromes as well as fault locations for the purposes of repair and fault/failure analysis. In addition, our design provides programmability for custom March algorithms with lower hardware cost. The combination of the on-line programming mode and diagnostic system dramatically reduces the effort in design debugging and yield enhancement. We have designed and implemented test chips with our BIST design. Experimental results show that the area overhead of the proposed BIST design is only 2.4% for a 128 KB SRAM, and 0.65% for a 2 MB one.     

中国电子商务思考

网络经济持续走低，但电子商务的发展大方向是不会改变的。在中国，目前的主要问题是宽带网的重复建设、认证机构建设缺乏有效监管、电子商务立法滞后、物流配送系统不完善、标准化问题成为电子商务发展的障碍等，当前应做的主要是：政策的宏观引导、示范推广、加强对宽带网和认证机构建设的监管等。     

Interfacial segregation of Ti in the brazing of diamond grits onto a steel substrate using a Cu-Sn-Ti brazing alloy

Diamond grits were brazed onto a steel substrate using a prealloyed Cu-10Sn-15Ti (wt pct) brazing alloy at 925 °C and 1050 °C. Due to the relatively high concentration of Ti in the brazing alloy, the braze matrix exhibited a composite structure, composed of β-(Cu,Sn), a Cu-based solid solution, and various intermetallic compounds with different morphologies. The reaction of Ti with diamond yielded a continuous TiC layer on the surfaces of the diamond grits. On top of the TiC growth front, an intermetallic compound, composed of Sn and Ti, nucleated and grew into a randomly interwoven fine lacey structure. An interfacial structure developed as the interwoven fine lacey phase was semicoherently bonded to the TiC layer, with the Cu-based braze matrix filling its interstices. The thickness of such a composite layer was increased linearly with the square root of isothermal holding time at 925 °C, complying with the law of a diffusion-controlled process. However, at 1050 °C, the segregation behavior of Ti and Sn to the interfaces between the TiC layer and the braze matrix diminished, due to the increased solubility of Ti in the Cu-based liquid phase. The enhanced dissolution of Ti in the Cu-based liquid phase at 1050 °C also caused the precipitation of rod-like CuTi with an average diameter of about 0.2 μm during cooling. SnTi₃ was the predominant intermetallic compound and existed in three different forms in the braze matrix. It existed as interconnected grains of large size which either floated to the surface of the braze matrix or grew into faceted grains. It also exhibited a nail-like structure with a mean diameter of about 1 μm for the rod section and a lamellar structure arising from a eutectic reaction during cooling.     

面向21世纪课程教材对地方综合大学电工学教学改革的影响--广西大学使用面向21世纪电工学课程系列教材的实践与探索

阐述了我校使用“面向21世纪”电工学课程系列教材的实践与探索过程，以及对我校电工学教学所产生的转折性影响和积极的导向作用，最后对教材提出了几点建议。