带皮囊式蓄能器的油压缓冲器的冲击研究

带皮囊式蓄能器的油压缓冲器是根据现行高速电梯发展的需要而设计的一种小尺寸液压缓冲器。通过带皮囊式蓄能器的油压缓冲器仿真与试验，研究这种新型缓冲器缓冲过程的冲击特性，以改善缓冲性能，从理论上为带皮囊式蓄能器的小尺寸油压缓冲器设计提供了一种可行的方法。     

SCHEDULING A SINGLE MACHINE TO MINIMIZE TWO CRITERIA: MAXIMUM TARDINESS AND NUMBER OF TARDY JOBS

In this paper we consider a single machine scheduling problem with two criteria; minimizing both maximum tardiness and the number of tardy jobs. We present both heuristic and branch-and-bound algorithms to find the schedule which minimizes the number of tardy jobs among all schedules having minimal maximum tardiness. Computational results show that problems with up to 40 jobs can be solved in less than one minute of computer time, and solution difficulty tends to increase as the range of due dates increases relative to the total processing time. We extend our results to generate all nondominated schedules for the two criteria. Computational experiments indicate that all non-dominated solutions to problems with 40 jobs can be generated. However, solution difficulty for these problems is highly dependent on problem parameters.     

ZnS窗口上过渡层的研究

研究采用ＡｌＮ为过渡层在ＺｎＳ红外光学窗口材料上进行金刚石膜保护。还对膜进行结构分析和光学测试。     

ON THE USE OF LP TO DESIGN MULTIDIMENSIONAL VIDEO FIR FILTERS

Filter design formulations simultaneously controlling both frequency and space-time behaviour are rather interesting for video applications. An FIR design tool addressing such formulations has been built using standard linear programming packages. The result has been quite satisfactory and the cost was very reasonable both in terms of man-time effort and required computing facilities. The construction of such a CAD tool and its performance are the subject of this paper.     

聚醚醚酮与酚酞型聚芳醚酮的共混研究

借助DSC、FTIR、PLM(偏光显微镜)、SEM技术研究了聚醚醚酮(PEEK)/酚酞型聚芳醚酮(PEK-C)共混物的相容性特征及结晶行为、结晶形态。结果表明该共混物是部分相容的,其相容程度与共混物的组分比及热历史有关;共混物中PEK-C对PEEK的结晶有阻碍,其阻碍与共混物的组分比及结晶条件有关;共混物的结晶形态对共混组分比有较大的依赖,同时还与结晶温度有关。     

纳米ZrO2缓冲膜的性能研究

用溶胶－凝胶技术,在金膜与基体不锈钢箔之间制备了一层ＺｒＯ２缓冲膜。在前期研究工作的基础上,通过ＴＥＭ、ＡＥＳ、ＳＥＭ等测试手段对ＺｒＯ２缓冲膜的结构及性能进行了表征。结果表明,溶胶－凝胶法制备的ＺｒＯ２缓冲肛螈粒度尺寸为纳米级;８５０℃处理后,没有涂覆缓冲膜的蒸金不锈钢箔与金膜之间存在着严重的互扩散反应,缓冲膜的涂覆可以有效地抑制高温互扩散反应。带有缓冲膜的蒸金不锈钢箔在高温热处理后仍能保持清晰     

AN APPROACH TO THE STUDY OF THE ATTITUDES OF WORKERS ON CONVEYOR BELT ASSEMBLY LINES

The paper describes a study covering 409 workers in the assembly factory of a large Belgian automobile company. It was desired to identify the factors which contributed, in both a positive and a negative way, to the attitudes of the men toward their work. The technique adopted was a free, but standardised, interview with each man whilst working on the line with him, the research worker having previously been trained and having worked on the line as an assembler. The data were subjected to an analysis of variance, and factors at work groups lying at the extremes of the distributions are discussed, reasons for their contribution to the total variance being drawn from the interview data.     

ON THE USE OF THE STRIP-YIELD MODEL TO PREDICT FATIGUE CRACK GROWTH UNDER IRREGULAR LOADING

Abstract— In this paper, the behaviour of the LEFM strip-yield model proposed by Newman and implemented in the FASTRAN II computer program is analyzed. The capabilities of the model to predict crack growth life under variable amplitude loading is considered. Special attention is paid to the effect of the constraint factors used to consider the stress condition (plane stress to plane strain), the effect of the finite length loading sequence and the effect of overloads into an irregular loading history. The results of simulation for 30 different loading histories obtained from the same stationary random process are analyzed and compared with the experimental results obtained for 2024-T351 aluminium alloy. The simulated lives present a fairly good fit with the experimental results, with a strong influence of the constraint factor selected and of the maximum peak in the loading history. Although predictions are usually good, it has been found that for any constraint factor producing good life predictions (with respect to the mean value of the Life obtained with the 30 loading histories) the results of each particular simulation may be over- or under-conservative depending on the maximum peak in the loading history used.     

ON THE USE OF QUASI-STATIC TESTING TO ASSESS IMPACT DAMAGE RESISTANCE OF COMPOSITE SHELL STRUCTURES

The response of various composite structures to transverse loading was studied through im-pact and quasi-static testing. The AS4/3501-6 graphtie/epoxy composite structures considered have a [±4.5_n/0_n]_s, layup configuration and include convex and concave shell sections, plates, and full cylinders. The impact tests fall within the so-called large-mass, low-velocity regime, where previous findings for composite plates indicate that quasi-static tests represent the impact response accurately; i.e., impact and quasi-static tests can be considered equivalent. This equivalence includes damage if the same peak force is reached in both the impact and quasi-static tests. The present work extends the impact and quasi-static equivalence from composite plates to various composite (shell) structures, including shells with an instability. Over nearly the entire range of impact events and shell structures considered, impact and quasi-static responses (including damage extent and distribution) are found to be equivalent. A small number of the most flexible (large-span, thin) specimens displayed a large-amplitude oscillatory impact loading response that was not observed for the quasi-static tests. These few specimens indicate one regime where the equivalence is limited The general equivalence demonstrated here for a wide range of composite structures has important implications for testing and design of damage-tolerant aerospace components. The findings also suggest that quasi-static experimentation can often be used to simulate the impact response (particularly damage) of composite shell structures.     

THE USE OF A SECONDARY STATE TO DETERMINE THE T-STRESS

Abstract— This paper examines the determination of the T-stress by making use of a secondary state and the complex-variable forms of the work reciprocal and Rice's J_x integrals in terms of the Muskhelishvili complex stress functions. A simple relationship is found which relates the stress intensity factors and T-stresses of the two states and is applied to the problem of a crack at the root of a notch.     

JOINT CONFIGURATION OF BACKBONE AND LOGICAL NETWORKS ON A RECONFIGURABLE PACKET-SWITCHED NETWORK WITH UNRELIABLE LINKS

Abstract

This paper considers a problem of configuring both backbone and logical networks in a reconfigurable packet-switched network where links are subject to failures. The objective is to design feasible backbone and logical networks at least cost where the network cost includes backbone link capacity expansion cost and average packet delay penalty cost due to link failures. The problem is formulated as a zero-one non-linear mixed integer programming problem, for which an effective solution procedure is developed by using a Lagrangean relaxation technique for finding a lower bound and a heuristic method is exploited for improving the upper bound of an intermediate solution. The solution procedure is tested for its effectiveness with various numerical examples.     

机械平面结合部静特性的研究及其在机床CAD中的应用

本文基于机械结合部的基础理论，建立了平面结合部的静力学模型及静变形数学模型，并确定了平面结合部的静刚度矩阵，为机床ＣＡＤ中选择最佳设计方案，预断设计效果及寻求合理设计参数提供了理论依据。所开发的软件是机器整机特性分析及预测软件系统的基础模块。     

ON THE USE OF VIBRATION AND ELECTRIC FIELDS TO FLUIDIZE AND DISPERSE PARTICULATE MATTER

ABSTRACT

Particulate matter is a statistical ensemble of interacting, non-identical particles. The fluidization and dispersal of dust is considered here from kinetic arguments and experiment. It is concluded that fluidization and dispersal of dust are independent physical processes arising from the action of vibration and steady stresses, respectively. Although the transition or correlation function for particulate systems is not as sharply defined as for the ideal-gas case, its general character is analogous with that for a condensing phase-transition with its critical condition broadened by the distribution of binding energies between the particles. The ratio of the net steady stress on the particles to the vibrational energy is the controlling factor in particle capture and entrainment.     

路堑开挖爆破中邻近民房风险评价的网格支持向量机模型

应用支持向量机理论并结合路堑开挖爆破特点,提出路堑开挖爆破中临近民房安全性评价的支持向量机回归模型。考虑爆破参数、地质条件和民房结构状况因素,选取最小抵抗线、孔距、排距、炸药单耗和民房的自振周期等16个影响较大的因素作为该模型的输入参数,房屋安全等级系数作为模型输出,利用网格搜索寻优方法对支持向量机模型的参数进行了优化。以19组路堑开挖爆破实测数据作为学习样本进行训练,对另外3组待判样本进行判别,并与多元回归、BP神经网络回归和实测结果进行对比。研究结果表明:建立的支持向量机回归模型对路堑开挖爆破中临近民房安全性评价效果良好,具有较高的预测精度。     

缓冲算子修正的单桩极限承载力的灰色预测

如何利用未达到破坏的试桩资料确定单桩极限承载力是一个重要的工程问题。根据单桩初始加载阶段的实测数据,建立以灰色系统理论为基础的GM(1,1)模型,预估单桩极限承载力,已在工程实际中取得一定的效果,但其精度有待提高。该文系统地论述了缓冲算子的概念和公理系统,探求了缓冲算子的使用规律,介绍了几种典型的缓冲算子及其特性,并采用缓冲算子修正了GM(1,1)模型以预测单桩的极限承载力。工程实例表明:该文的模型提高了预测精度,可在工程实际和理论研究中推广应用。     

路堑开挖爆破中邻近民房风险评价的网格支持向量机模型

应用支持向量机理论并结合路堑开挖爆破特点,提出路堑开挖爆破中临近民房安全性评价的支持向量机回归模型.考虑爆破参数、地质条件和民房结构状况因素,选取最小抵抗线、孔距、排距、炸药单耗和民房的自振周期等16个影响较大的因素作为该模型的输入参数,房屋安全等级系数作为模型输出,利用网格搜索寻优方法对支持向量机模型的参数进行了优化.以19组路堑开挖爆破实测数据作为学习样本进行训练,对另外3组待判样本进行判别,并与多元回归、BP神经网络回归和实测结果进行对比.研究结果表明:建立的支持向量机回归模型对路堑开挖爆破中临近民房安全性评价效果良好,具有较高的预测精度.     

路堑开挖爆破中邻近民房风险评价的网格支持向量机模型

应用支持向量机理论并结合路堑开挖爆破特点,提出路堑开挖爆破中临近民房安全性评价的支持向量机回归模型。考虑爆破参数、地质条件和民房结构状况因素,选取最小抵抗线、孔距、排距、炸药单耗和民房的自振周期等16个影响较大的因素作为该模型的输入参数,房屋安全等级系数作为模型输出,利用网格搜索寻优方法对支持向量机模型的参数进行了优化。以19组路堑开挖爆破实测数据作为学习样本进行训练,对另外3组待判样本进行判别,并与多元回归、BP神经网络回归和实测结果进行对比。研究结果表明:建立的支持向量机回归模型对路堑开挖爆破中临近民房安全性评价效果良好,具有较高的预测精度。     

EFFECT OF LOADING WITH AIM OIL AEROSOL ON THE COLLECTION EFFICIENCY OF AN ELECTRET FILTER

ABSTRACT

Loading of an electret filter changes the distribution of electrical field in the filter from its preloading condition, and, therefore, affects the filtration efficiency of the filter. Liquid droplets collected on electret filters cause degradation of the electrostatic enhancement of filtration efficiency because of charge neutralization and the formation of a dielectric coating over die charged fibers. In this study, calculations were made for the penetration of aerosol particles through a spun-type electret filter as a function of the particulate loading. An assumption was made that each charge collected neutralized one charge of opposite polarity on the fibers of the filter. It was also assumed that the electrostatic charges present on the particles followed the Boltzmann equilibrium charge distribution. The decrease in fiber charge and resulting increase in penetration were calculated as a function of time and of total particulate loading on the filter. The calculated penetrations were compared with experimental measurements of loading on a spun fiber electret filter challenged with monodisperse liquid droplets of bis-Ethylhexyl Sebacate with equilibrium charge distribution and with zero charge. The rate at which the penetration increased was found to be the same for particles with zero charge as for particles with equilibrium charge distribution. For 1 um diameter droplets with equilibrium charge the theory predicted complete discharge of the filter at a loading of around 200 g/m². Experimentally, only about 0.3 g/m² was required. This difference indicates the presence of additional mechanisms for the discharge of the fibers.     

EFFECT OF LOADING WITH AIM OIL AEROSOL ON THE COLLECTION EFFICIENCY OF AN ELECTRET FILTER

Loading of an electret filter changes the distribution of electrical field in the filter from its preloading condition, and, therefore, affects the filtration efficiency of the filter. Liquid droplets collected on electret filters cause degradation of the electrostatic enhancement of filtration efficiency because of charge neutralization and the formation of a dielectric coating over die charged fibers. In this study, calculations were made for the penetration of aerosol particles through a spun-type electret filter as a function of the particulate loading. An assumption was made that each charge collected neutralized one charge of opposite polarity on the fibers of the filter. It was also assumed that the electrostatic charges present on the particles followed the Boltzmann equilibrium charge distribution. The decrease in fiber charge and resulting increase in penetration were calculated as a function of time and of total particulate loading on the filter. The calculated penetrations were compared with experimental measurements of loading on a spun fiber electret filter challenged with monodisperse liquid droplets of bis-Ethylhexyl Sebacate with equilibrium charge distribution and with zero charge. The rate at which the penetration increased was found to be the same for particles with zero charge as for particles with equilibrium charge distribution. For 1 um diameter droplets with equilibrium charge the theory predicted complete discharge of the filter at a loading of around 200 g/m². Experimentally, only about 0.3 g/m² was required. This difference indicates the presence of additional mechanisms for the discharge of the fibers.