Hyperelasticity Model for Finite Element Analysis of Natural and High Damping Rubbers in Compression and Shear

Rate-independent monotonic behavior of filled natural rubber and high damping rubber is investigated in compression and shear regimes. Monotonic responses obtained from tests conducted in both regimes demonstrate the prominent existence of the Fletcher–Gent effect, indicated by high stiffness at low strain levels. An improved hyperelasticity model for compression and shear regimes is proposed to represent the rate-independent instantaneous and equilibrium responses including the Fletcher–Gent effect. A parameter identification scheme involving simultaneous minimization of least-square residuals of uniaxial compression and simple shear data is delineated. The difficulties of identifying a unique set of hyperelasticity parameters that hold for both compression and shear deformation modes are thus overcome. The proposed hyperelasticity model has been implemented in a general purpose finite element program. Finite element simulations of experiments have shown the adequacy of the proposed hyperelasticity model, estimated parameters, and employed numerical procedures. Finally, numerical experiments were conducted to further explore the potential of the proposed model, and estimated parameters in analyzing rubber layers of a base isolation bearing subjected either to compression or to a combination of compression and shear.     

深亚微米高性能微处理器运算单元的设计

介绍了基于0.18微米的微处理器运算单元的设计实现。以乘法器的设计实现为例，给出乘法嚣的版图设计和电路仿真结果，还给出整体芯片的版图设计方法，并列举了在版图设计中对深亚微米设计问题的考虑。     

数据挖掘在供应管理中的应用

文章对供应管理现状进行了分析,并针对目前物资管理部门普遍存在的库存储备量过大、占用资金过多、资金利用和周转率不高、物资的进出仓工作量大而且容易出错、经济效益低等诸多问题,指出了在管理工作中引入数据挖掘技术进行科学管理的重要性。通过计算机系统的管理,使物资供应管理达到了保证物质供应、降低采购成本、优化库存结构、减少库存资金、加速资金周转、提高经济效益的目的。     

Evaluation of PEMFC power systems for UPS base station applications

For UPS applications such as the mobile phone base station, the selection of PEM fuel cell technology seems only feasible for the case of a heavy-duty service time requirement. The weight reduction of the whole energy system using fuel cell technology is significant, and the volume and the cost can also be superior when the service time is over 24 h. If the production cost and the module volume of fuel cell system can be further reduced, the results will be more promising.     

基于MC9S12NE64型单片机的嵌入式以太网连接

分析基于单片机的以太网连接方案,介绍MC9S12NE64型16位单片机的特性及其最小系统的硬件设计,给出MC9S12NE64的初始化过程、主程序和TCP/IP协议栈实现的思想.     

Taguchi approach for optimization of the bleeding on cement-based grouts

Investigations on the effect of the bentonite (B), fly ash (FA) and silica fume (SF) on the bleeding of cement-based grouts were reported here. Three additives (B, FA and SF) were used in the grout mixes to improve the bleeding of the grouts. Taguchi method was applied for the experiments and standard L₁₆ orthogonal array (OA) with three factors and four levels were chosen. In the preparation of the cement grouts, B, FA and SF were used at the ratios of 0–0.5–1–3%, 10–20–30–40% and 0–5–10–20%, respectively. The experiments were performed for three water/solid (W/S) ratios. Experimental results showed that the most effective material for the bleeding is SF. The bleeding decreased with the increase in SF and B ratio, while there was no noticeable difference with the increase of FA. Optimum conditions for minimum bleeding were obtained at 3% B, 10% FA and 20% SF for both grouts with W/S ratios of 0.75 and 1.0, while they were obtained 3% B, 20% FA and 20% SF for W/S ratio of 1.25. The Taguchi method was found to be promising tool to obtain the optimum conditions for such studies.     

基于nRF2401的近距离点对多点无线通信系统

本文介绍了一种基于nRF2401无线收发芯片的近距离点对多点无线通信系统的设计方法并以ATmega64L单片机为核心，给出了该系统的硬件电路设计及相关软件设计要点，实践表明，该系统控制简单，使用方便，工作稳定性很高。     

一种P2P网络中基于位置感知的节点选择策略

P2P网络作为一种覆盖网络,邻居节点的选择若不考虑网络层、物理层信息,将导致较低的数据传输速度和不必要的跨运营商流量,从而大大限制P2P技术的应用。位置感知策略可以解决这些问题。本文对现有位置感知策略进行分类,并通过分析比较指出了现有位置感知策略的优缺点。提出了一种基于IP地址库的简单有效的节点选择策略,能够感知节点的运营商信息和物理位置。     

DVB-C系统在高斯信道下的理论性能

本文对DVB—C系统在高斯信道下的理论性能进行了分析，并进行了蒙特卡罗仿真，获得了64QAM的BER～Eb/N。、Eb/N。～MER和BER～MER性能曲线。此外还对MER、C／N、S／N、Eb/N。的关系进行了分析，结合仿真结果和测量结果重点讨论了MER在数字有线电视测量和实践中的重要作用。     

Limit-State Curve of Base-Course Material and Its Relevance for Resilient Modulus Testing

The limit state characteristics of base-course granular materials were obtained using a typical triaxial testing equipment devoted to the measurement of resilient modulus. Accurate monitoring of axial strain during isotropic and anisotropic compression was used to determine the stress conditions where significant irrecoverable strains occur for samples prepared by static compression, Proctor rammer, and vibratory compaction. The limit state curve is highly anisotropic, centered about the q/p = 1 line. It is sensitive to sample preparation technique and fines content. The Strategic Highway Research Program (SHRP) procedure corresponds to stress paths during conditioning and repeated loading that remain within the limit state curve of the control base course material containing 3.5% fines. The resilient modulus values reflect henceforth the behaviour of the same material with its original particle contact distribution. The Laboratoires des Ponts et Chaussées (LCPC) procedure is characterized by stress paths that cross the original limit state curve of the Proctor compacted samples. Particle contact distribution changes thus continuously as the limit state curve expands in response to the various stress paths used in this procedure. The resilient modulus values correspond to samples with different fabrics. A simple procedure based on isotropic loading has been proposed for the determination of a simplified limit state curve of base course materials with the intent of specifying the testing conditions for obtaining adequate resilient modulus values.