Limit load analysis of strength undermatched welded T-joints under bending

An increasing amount of laser beam welded T‐joints (e.g. skin‐stringer) of aluminium alloys are now in use in advanced fuselage applications designed as ‘integral structures’ for weight and cost savings. It is known that weld joints generally show lower strength (undermatching) than base metal in both laser beam and friction stir welded joints of 6xxx series Al‐alloys. Damage tolerance considerations in terms of the residual strength of such joints require limit load solutions to be used in engineering fitness‐for‐service (FFS) analysis. The paper, therefore, provides an upper bound limit load solution in closed form for welded T‐joints (idealized) with strength undermatching and subject to a bending moment. In addition to the necessary requirements of the upper bound theorem, the kinematically admissible velocity field chosen leads to a stress field, which satisfies the equilibrium equations and some stress boundary conditions in the plastic zone. This is an advantage of the solution and, therefore, it is expected that the upper bound obtained is close to the exact limit load of such joints.     

Reliability Analysis of Single-Degree-of-Freedom Elastoplastic Systems. II: Suboptimal Excitations

A method for constructing an approximation of the critical excitation that drives an elastoplastic system from rest to a target threshold at a specified time instant, referred to as the “suboptimal excitation,” is presented in this paper. It is based on the observations gained from study of the critical excitations in the companion paper. Essentially, for the usual case of interest where the failure time is not small compared to the natural period, the duration of the positive and negative pulses of the critical excitation are roughly equal to half of the natural period. This consideration allows for a simple intuitive approximation of the critical excitation. The amplitudes of the positive and negative pulses are obtained in closed forms using energy balance. Numerical investigations show that the critical excitations are well approximated by the suboptimal excitations.     

基于Delphi的报童模型的实现与动态仿真

已往库存论中的决策模型,它是把现实过程用数学的方法进行分析,得到决策值,但不能看到决策的过程,不能反映出现实生活中的不确定性、动态性。运用Delphi 7.0和SQL server 2000对销售过程进行了动态仿真,利用Newsboy模型的推广(S,s)订购策略来监控库存并做出决策,这样就体现出此过程的不确定性、动态性;且举出了一个仿真商品销售的实例,对其中的一些关键技术,如何仿真、算法的实现等进行了阐述。     

ISIS全局优化多道反演技术在墩2块岩性油藏描述中的应用

为进一步落实墩2块戴一段岩性油藏成藏规模及分布规律，针对该储层薄、横向变化快的特点，利用ISIS全局优化多道反演技术，对该构造区岩性储层进行了精细描述，较好的预测出戴一段储层平面分布规律。     

新型复合弹簧的研究

提出一种金属圆锥弹簧与橡胶圆锥弹簧复合而成的弹簧．分析表明：它可以应用于弹性耦合激励振动筛和座式直线振动筛。     

微波宽频带功率负载的研究

介绍了５００Ｗ宽频带功率负载的设计及实验结果，并将研究成果扩展到１０～１０００Ｗ范围。负载主要技术指标：输入阻抗５０Ω，频带宽度０～１０００ＭＨｚ，电压驻波比≤１．１．表面最高温升△ｔ≤１００℃。     

单层球面网壳地震反应特征分析

考虑不同矢跨比、荷载、跨度和支座刚度等多种因素的影响,对单层球面网壳在地震作用下的反应进行了较全面的研究,给出了其随各参数变化的规律,得出了在单层球面网壳抗震设计中起控制作用的是水平地震作用而不是竖向地震作用等有益的结论.此外本文还给出了由于阻尼比不同而需对引用现行抗震规范反应谱分析的网壳地震作用进行修正的建议.     

地震数据采集系统中频谱均衡滤波器的理论设计

地层的高频吸收衰减效应是导致地震勘探分辨率不高的主要原因，在高分辨率野外地震数据系统中，频谱均衡滤波器所设置的重要部件。文章以频谱均衡滤波器的原理和地层吸收衰减特性为基础，用计算机模拟的方法研究地层吸收衰减使分辨率降低的程度和频谱均衡滤波器对分辨率的补偿效果，给出了较好的频谱均衡滤波器的设计方案。     

逻辑程序的一种并行执行模型

本文基于静态相关性分析和动态调整相结合的方法，提出了一种逻辑程序的执行模型，它不仅开发了“与“并行，同进也开发了一定的“或“并行，从而有效地加速了逻辑程序的执行。     

盘锦地区电力负荷的季节性分析

本文从盘锦地区１９８７－１９９３年电力负荷的原始资料入手，运用移动平均并加以改良的方法，从具有季节性变化的电力负荷系列中，分离出季节性分量，提示了电力负荷发展变化的规律。文中分析了盘锦地区七年间电力负荷发展的自身特点，指出其循环变化的转折点，给出了未来近期负荷变化的趋势，为电力行业制定规划和组织生产提供了依据，对供电企业合理安排生产计划、适应市场经济带来启示。