结构发泡成型技术

介绍了结构发泡的工艺过程,并将该工艺与普通注塑工艺作了比较,阐述了结构发泡成型技术和优点及装置的关键技术和产品特点。结构发泡了工艺的多点喷嘴顺序注射技术决定了设备低压、低锁模力的特性,从而允许模具使用低成本铝模,增大模板尺寸,增强模塑能力,并能保证尺寸差异较大的制品质量,减轻制品质量,提高制品强度。     

Optimal boundary control of coupled parabolic PDE–ODE systems using infinite-dimensional representation

The optimal boundary control problem is studied for coupled parabolic PDE–ODE systems. The linear quadratic method is used and exploits an infinite-dimensional state-space representation of the coupled PDE–ODE system. Linearization of the nonlinear system is established around a steady-state profile. Using appropriate state transformations, the linearized system has been formulated as a well-posed infinite-dimensional system with bounded input and output operators. It has been shown that the resulting system is a Riesz spectral system. The linear quadratic control problem has been solved using the corresponding Riccati equation and the solution of the corresponding eigenvalue problem. The results were applied to the case study of a catalytic cracking reactor with catalyst deactivation. Numerical simulations are performed to illustrate the performance of the proposed controller.     

Characterization of Biogenic Silica Generated by Thermo Chemical Treatment of Rice Husk

This study presents two routes to produce amorphous silica from an Egyptian rice husk under conditions optimized for least environmental impact and low cost. The first route includes thoroughly washing of the husk sample with water, dry milling and leaching with citric acid. The leaching process was applied in two stages, that is, at 323 K for 180 min and then at 353 K for 60 min. After washing and drying, the leached sample was subjected to a heat treatment in a muffles furnace at four sequential steps. The second route includes all the previously mentioned steps, except the citric acid leaching. The final products were characterized using x-ray fluorescence analysis, carbon content analysis, x-ray diffraction, differential thermal analysis, nitrogen adsorption, mercury intrusion, and scanning electron microscopy. The results show that the citric acid leaching has many advantages with respect to silica yield and porosity as well.     

Optimization of large‐scale truss structures using sparse SAND formulations

Sparsity features of simultaneous analysis and design (SAND) formulations are studied and exploited for optimization of large‐scale truss structures. Three formulations are described and implemented with an existing analysis code. SAND formulations have large number of variables; however, gradients of the functions and Hessian of the Lagrangian are quite sparsely populated. Therefore, this structure of the problem is exploited and an optimization algorithm with sparse matrix capability is used to solve large‐scale problems. An existing analysis software is integrated with an optimizer based on a sparse sequential quadratic programming (SQP) algorithm to solve sample problems. The formulations and algorithms work quite well for the sample problems, and their performances are compared and discussed. For all the cases considered, the SAND formulations out perform the conventional formulation except one case. Further research is suggested to fully study and utilize sparse features of the alternative SAND formulations and to develop more efficient sparse solvers for large‐scale and more complex applications. Copyright © 2006 John Wiley & Sons, Ltd.     

配电网无功补偿算法研究综述

随着供需矛盾的加深及人们对供电质量要求的提高，配电网无功补偿成为目前供电部门一个重视的研究课题。针对配电网独特的特点，给出了配电网无功补偿的一般模型，并介绍了确定补偿电容位置、容量的传统算法及现行的各种人工智能方法，指出了各种算法的优缺点及改进之处，较全面地反映无功补偿算法的研究情况。     

Numerical investigation of surface topography and residual stress after abrasive water jet sequential peening (AWJSP)

Abstract

This article reveals the formation mechanism of surface topography and the formation and coupling mechanism of residual stress field (RSF) after abrasive water jet sequential peening (AWJSP) that can sequential peening on the material surface at a certain distance interval, and proposes a mathematical model of surface dimple characteristic verified by simulation results. In addition, the influences of shot velocity v₀, shot radius R and the distance between the center of adjacent shots D_C on surface topography and RSF were also investigated. Results show the surface dimple forms resulting from the material plastic strain, and the residual stress (RS) is mainly induced by the unrecovered elastic strain resulting from the hindering of plastic strain. Decreasing v₀, R or D_C can decrease the surface roughness R_t, while increasing v₀ and R is beneficial to induce a large and deep compressive RS layer. D_C influences the whole distribution of compressive RS layer directly.     

用计算器编程计算缓圆曲线上的测量坐标

根据道路放线野外作业流动的特点 ,特提出用可编程计算器编程计算缓圆曲线上任意点测量坐标的方法 ,以便在道路施工中进行坐标制放线     

河北农业大学西校区规划创意

河北农业大学西校区规划设计方案通过对校园空间意象的营造、人性化交通组织以及体现校园精神的环境设计，塑造出具有农大特色的校园形象。     

电力市场的输电阻塞管理模型与Matlab编程计算

首先编写MATLAB程序,直接利用各机组的报价方案表和爬坡速率以及段容量得出出力分配初始方案;然后,建立了简明的阻塞费用计算公式;最后,建立了双目标非线性规划进行阻塞管理,并编写了相应的MATLAB计算程序对问题进行求解.     

自动铺带轨迹规划中测地线算法研究

本文针对复合材料自动铺放轨迹规划中自然路径求解中的测地线问题给出了求解两点之间的测地线的数值计算方法。该方法将微分方程的边值问题转化为初值问题,在初始方向的选取上较以往方法几何意义更为直观,算例证明算法的正确性。