增强科技素养，提高打赢能力

增强高级指挥员的科技认知力、创新力、运用力是科技强军的必然要求。本文从战争演变、融合发展、应对威胁切入,对高级指挥员如何提升科技认知力层次、增强科技创新力效能、提高科技运用力水平谈了几点初步思考。     

Short‐term capacity allocation problem with tool and setup constraints

We consider a short‐term capacity allocation problem with tool and setup constraints that arises in the context of operational planning in a semiconductor wafer fabrication facility. The problem is that of allocating the available capacity of parallel nonidentical machines to available work‐in‐process (WIP) inventory of operations. Each machine can process a subset of the operations and a tool setup is required on a machine to change processing from one operation to another. Both the number of tools available for an operation and the number of setups that can be performed on a machine during a specified time horizon are limited. We formulate this problem as a degree‐constrained network flow problem on a bipartite graph, show that the problem is NP‐hard, and propose constant factor approximation algorithms. We also develop constructive heuristics and a greedy randomized adaptive search procedure for the problem. Our computational experiments demonstrate that our solution procedures solve the problem efficiently, rendering the use of our algorithms in real environment feasible. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

A continuous‐time strategic capacity planning model

Capacity planning decisions affect a significant portion of future revenue. In the semiconductor industry, they need to be made in the presence of both highly volatile demand and long capacity installation lead‐times. In contrast to traditional discrete‐time models, we present a continuous‐time stochastic programming model for multiple resource types and product families. We show how this approach can solve capacity planning problems of reasonable size and complexity with provable efficiency. This is achieved by an application of the divide‐and‐conquer algorithm, convexity, submodularity, and the open‐pit mining problem. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

南水北调中线工程安阳段渠坡换填土的强度特性研究

为了分析南水北调中线工程安阳段渠坡的稳定性,对该渠坡换填土在不同含水率下进行了不固结不排水三轴剪切试验.研究结果表明:剪切速率对基质吸力的影响较大,而对强度的影响较小;通过比较确定了合适的剪切速率;含水率相同的试样在不同围压下的强度值在pf -qf坐标上呈良好的线性关系;得到了试样在不同含水率下的总强度指标,建立了总内...     

弹性基上圆柱管弯曲行为的高阶剪切梁理论解

以弹性基上圆柱管为研究对象,基于高阶剪切变形梁理论推导了Winkler弹性基圆柱管弯曲变形的高阶剪切梁理论控制方程,给出四种典型工况弯曲问题的精确解.研究表明,无须假设剪切修正系数,只需引入适当横截面翘曲形状函数,高阶梁理论在圆柱管内外表面满足剪应力τxr为零的边界条件,且对于不同长径比和厚径比的圆柱管弯曲问题均能提供...     

A higher order coupled frequency characteristics study of smartmagneto-electro-elastic composite plates with cut-outs using finite element methods

This article deals with investigating the effect of cut-outs on the natural frequencies of magneto-electro-elastic (MEE) plates incorporating finite element methods based on higher order shear deformation theory (HSDT). In order to consider the influence of cut-out, the energy of the cut-out domain is sub-tracted from the total energy of the entire plate. The governing equations of motions are derived through incorporating Hamilton's principle and the solution is obtained using condensation technique. The proposed numerical formulation is verified with the results of previously published literature as well as the numerical software. In addition, this research focuses on evaluating the effect of geometrical skewness and boundary conditions on the frequency response. The influence of cut-outs on the degree of coupling between magnetic, electric and elasticfields is also investigated.     

Numerical simulation study on penetration performance of depleted Uranium (DU) alloy fragments

Due to its high strength, high density, high hardness and good penetration capabilities, Depleted ura-nium alloys have already shined in armor-piercing projectiles. There should also be a lot of room for improvement in the application of fragment killing elements. Therefore, regarding the performance of the depleted uranium alloy to penetrate the target plate, further investigation is needed to analyze its advantages and disadvantages compared to tungsten alloy. To study the difference in penetration per-formance between depleted uranium alloy and tungsten alloy fragments,firstly, a theoretical analysis of the adiabatic shear sensitivity of DU and tungsten alloys was given from the perspective of material constitutive model. Then, taking the cylindrical fragment penetration target as the research object, the penetration process and velocity characteristics of the steel target plates penetrated by DU alloy frag-ment and tungsten alloy fragment were compared and analyzed, by using finite element software ANSYS/LS-DYNA and Lagrange algorithm. Lastly, the influence of different postures when impacting target and different fragment shapes on the penetration results is carried out in the research. The results show that in the penetration process of the DU and tungsten alloy fragments, the self-sharpening properties of the DU alloy can make the fragment head sharper and the penetrating ability enhance. Under the same conditions, the penetration capability of cylindrical fragment impacting target in vertical posture is better than that in horizontal posture, and the penetration capability of the spherical fragment is slightly better than that of cylindrical fragment.     

An interface shear damage model of chromium coating/steel substrate under thermal erosion load

The Cr-plated coating inside a gun barrel can effectively improve the barrel's erosion resistance and thus increase the service life.However,due to the cyclic thermal load caused by high-temperature gun-powder,micro-element damage tends to occur within the Cr coating/steel substrate interface,leading to a gradual deterioration in macro-mechanical properties for the material in the related region.In order to mimic this cyclic thermal load and,thereby,study the thermal erosion behavior of the Cr coating on the barrel's inner wall,a laser emitter is utilized in the current study.With the help of in-situ tensile test and finite element simulation results,a shear stress distribution law of the Cr coating/steel substrate and a change law of the interface ultimate shear strength are identified.Studies have shown that the Cr coating/steel substrate interface's ultimate shear strength has a significant weakening effect due to increasing temperature.In this study,the interfacial ultimate shear strength decreases from 2.57 GPa(no erosion)to 1.02 GPa(laser power is 160 W).The data from this experiment is employed to establish a Cr coating/steel substrate interface shear damage model.And this model is used to predict the flaking process of Cr coating by finite element method.The simulation results show that the increase of coating crack spacing and coating thickness will increase the service life of gun barrel.     

爆炸复合接头剪切强度测试方法研究

参照正交各向异性层压复合板层间剪切强度的测试方法,提出了用于测试爆炸复合接头复合界面剪切强度的3种方法;并建立三维有限元模型,分别对3种测试方法进行模拟;最后分别对3种方法进行了测试试验.结果表明,3种试验方法均能有效测试爆炸复合接头的剪切强度,其中对称试件双切口拉伸法最适合实际应用.     

Excess capacity in weapons production: An empirical analysis∗ †

This paper analyzes a set of observations by the Congressional Budget Office (CBO) on individual weapons systems regarding whether large amounts of excess capacity exist and whether short run average cost (SRAC) appears to be severely decreasing. It is shown that the amount of excess capacity and steepness of SRAC are essentially independent of output rate. It is then argued that this suggests that production is occurring in inefficiently large plants—i.e.—off the long run cost curve.