Boundary-Value Problems of the Theory of Thin and Nonthin Orthotropic Shells with Account of Nonlinearly Elastic Properties and Low Shear Rigidity of Composite Materials

The basic geometric and physical relations and resolving equations of the theory of thin and nonthin orthotropic composite shells with account of nonlinear properties and low shear rigidity of their materials are presented. They are derived based on two theories, namely the theory of anisotropic shells employing the Timoshenko or Kirchhoff-Love hypothesis and the nonlinear theory of elasticity and plasticity of anisotropic media in combination with the Lagrange variational principle. The procedure and algorithm for the numerical solution of nonlinear (linear) problems are based on the method of successive approximations, the difference-variational method, and the Lagrange multiplier method. Calculations of the stress-strain state for a spherical shell with a circular opening loaded with internal pressure are presented. The effect of transverse shear strains and physical nonlinearity of the material on the distribution of maximum deflections and circumferential stresses in the shell, obtained according to two variants of the shell theories, is studied. A comparison of the results of the problem solution in linear and nonlinear statements with and without account of the shell shear strains is given. The numerical data obtained for thin and nonthin (medium thick) composite shells are analyzed.     

Effects of permeability and viscosity in linear polymeric gels

We propose and analyze a mathematical model of the mechanics of gels, consisting of the laws of balance of mass and linear momentum of the polymer and liquid components of the gel. We consider a gel to be an immiscible and incompressible mixture of a nonlinearly elastic polymer and a fluid. The problems that we study are motivated by predictions of the life cycle of body‐implantable medical devices. Scaling arguments suggest neglecting inertia terms, and therefore, we consider the quasi‐static approximation to the dynamics. We focus on the linearized system about stress‐free states, uniform expansions, and compressions and derive sufficient conditions for the solvability of the time‐dependent problems. These turn out to be conditions that guarantee local stability of the equilibrium solutions. We also consider non‐stress free equilibria and states with residual stress and derive an energy law for the corresponding time‐dependent system. The conditions that guarantee stability of solutions provide a selection criteria of the material parameters of devices. The boundary conditions that we consider are of two types, displacement‐traction and permeability of the gel surface to the fluid. We address the cases of viscous and inviscid solvent, assume Newtonian dissipation for the polymer component, and establish existence of weak solutions for the different boundary permeability conditions and viscosity assumptions. We present two‐dimensional, finite element numerical simulations to study stress concentration on edges, this being the precursor to debonding of the gel from its substrate. Copyright © 2015 John Wiley & Sons, Ltd.     

非线性优化方法在大气和海洋科学数值研究中的若干应用

控制大气和海洋运动的模式是复杂的非线性模式,在考虑到线性奇异向量和线性奇异值只能描述切线性模式有效时段内小扰动发展的情况下,介绍了作者们近年来用非线性优化方法数值研究大气和海洋科学的有关工作,其中包括非线性奇异向量和非线性奇异值、条件非线性最优扰动、以及它们在数值天气和气候可预报性研究中的应用．结果表明,上述非线性优化方法在很大程度上揭示了大气和海洋运动的非线性特征;此外,对可预报性问题的新分类也做了详细介绍,即最大可预报时间、最大预报误差和最大允许初始误差A·D2这种分类的应用背景是针对数值天气预报和气候预测产品的评价;最后,讨论了数值模式敏感性分析的非线性优化方法,该方法在一定条件下可以定量识别模式误差和初始误差,量化判断数值模式的模拟能力．     

A 3D modeling of static and forward smoldering combustion in a packed bed of materials

A three-dimensional (3D) model based on the first principles of mass, momentum and energy was developed that numerically simulates the processes of static and forward smoldering in a porous packed bed of plant materials. The packed bed contains cellulose material or tobacco (cigarette) wrapped in a porous paper and surrounded by an ambient air. Other major characteristics of the model are including the effects of buoyancy forces in the flow field, separate treatment of solid and gas in a thermally non-equilibrium environment, and use of multi-precursor kinetic models for the pyrolysis of staring material and oxidation of char. The changes in porosity due to pyrolysis and char oxidation and the effect of porosity on the bed permeability and gas diffusivity are included. The mass, momentum, energy, and species transport equations are solved in a discretized computational domain using a commercially available computational fluid dynamics (CFD) code. The simulation results show that the model reasonably reproduces the major features of a burning cigarette during smoldering and puffing and are in a good agreement with the existing experimental results for cigarettes. Results include the velocity profiles, gas and solid temperatures, coal shape, burn rates, profile and transport of gas and vapor species throughout the packed bed, dilution through the wrapper paper and ventilation in the filter section, and the mass fraction of some pyrolysis and oxidation products in the mainstream and sidestream flows.     

数量折扣契约下制造商与零售商库存合作联盟的稳定性

针对实际中存在的不同形式合作联盟,研究了零售商库存合作联盟,以及制造商与零售商库存合作联盟所形成混合合作联盟的稳定性。在随机需求情况下,制造商通过自身中心仓库向多个零售商提供数量折扣契约,首先证明了两个合作联盟的最优运作决策都存在且唯一,并给出了制造商向零售商库存合作联盟提供数量折扣契约的形式,然后分析了两种合作联盟的稳定性,并得出混合合作联盟的总期望利润要高于零售商库存合作联盟的结论。     

行业结构环境的序参量分析方法研究

行业结构环境分析是发现和掌握行业运行规律与发展状况的必经之路,也是在企业战略管理中的重要组成部分,其结果直接影响着企业战略决策与实施。针对企业战略管理的新价值理念,本文在协同学与竞优理论的基础上,通过对行业内群体结构特性与企业行为的重新考察,建立了行业结构环境分析的一种新方法即序参量分析方法与其应用范例。本文的研究结果,如行业内多层结构、企业群组定位及分布特性、行业基本发展模式、标杆与协同伙伴、企业群组或群组内企业构成与绩效之间的关系等都可为实现符合现代产业发展环境的企业战略管理提供方向性辅助与技术支持。     

乡村绿色生态旅游适宜等级VIKOR评估方法

针对乡村绿色生态旅游特征,并考虑旅游者个体感受与群体效益,本文从乡村绿色生态旅游开发与适宜评级概念出发,提出乡村绿色生态旅游适宜等级VIKOR评估模型与方法。首先,从等级评估的概念与内涵出发,刻画乡村绿色生态旅游适宜评级问题,避免混淆旅游适宜评级和排序两个本质不同的问题。然后,构建乡村绿色生态旅游适宜等级评估指标及隶属函数,提出评估指标的熵权确定方法。其次,提出乡村绿色生态旅游适宜等级VIKOR评估模型与二元语义等级评估方法。最后,通过案例研究和比较分析,说明本文所提模型与方法的合理性、可行性与实用性。     

我国经济产出与钢社会蓄积的关联分析

基于动态物质流分析方法及时间序列分析方法,本文以我国1949-2012年年度数据为样本,研究了工业化演进过程中我国经济产出与钢社会蓄积之间的关联。研究结果表明,随着经济的发展和工业化进程的演进,钢以实物产品的形式不断蓄积于我国社会当中,且蓄积的速度不断加快。我国经济产出与钢的社会蓄积之间存在长期协整关系,钢的社会蓄积既能在短期内推动经济的增长,又影响着经济产出的长期整体走势,而经济产出只是钢社会蓄积变化的长期原因。这说明我国的经济建设高度依赖钢的使用,而且经济增长对钢需求的拉动是一个长期的过程,不会在短期内对钢的需求造成显著影响。     

网约车新政下平台和乘客的Stackelberg博弈模型及策略研究

近年来,滴滴和优步等网约车平台的出现给城市居民出行带来了新的选择,然而随着新政的实施以及垄断巨头的酝酿诞生,网约车平台是否会降补贴提车价成为消费者最为关心的问题。文章构建网约车平台和乘客之间的Stackelberg博弈模型,分析了网约车平台的补贴和抽成策略对乘客是否选择网约车出行的决策行为以及网约车市场均衡的影响。理论研究和仿真结果表明:网约车平台合理的补贴力度和抽成力度可以有效规避行政监管成本增加和乘客资源流失的风险,提高双方的收益,实现社会的帕累托最优。     

关系治理与契约治理导向匹配状态的量化研究——以公私合作模式下A地铁项目为例

近年来关系治理(RG)、契约治理导向(CG)是项目管理领域研究较多的议题,但是关于二者匹配状态的量化研究却很少。为此,基于问卷调研数据,利用相关性权重法对RG状态、CG状态进行了量化,在此基础上,构建了RG与CG匹配模型,并进行了案例分析。研究结果表明:对RG状态、CG状态的量化研究具有可行性,且实现了对RG与CG最佳匹配状态的量化研究。以上研究结论有助于理解RG与CG的匹配机理,对实现二者的有效匹配及项目绩效的改善具有重要的理论和实践指导意义。     

井下钻柱纵向横向耦合振动模型建立与数值分析

针对井下钻柱运动的复杂性,基于动力学理论,建立了井下钻柱纵向和横向耦合振动的数学模型,并进行数值求解及分析.根据井下钻柱的实际工况,以整个井下钻柱为研究对象,提出了钻柱纵向和横向耦合振动的动力方程,并利用解析法和无量纲法分别求解出其动刚度和动阻尼的表达式,以及钻柱前两阶振动的固有频率.分析结果表明:当井下钻柱振动频率增大时,其动刚度呈幅值衰减的周期性变化,而其动阻尼呈幅值增强的周期性变化;井下钻柱长度和横截面面积越大,其动刚度和动阻尼的幅值越小;井下钻柱的Poisson(泊松)比对其振动的动刚度、动阻尼和前两阶固有频率没有影响;同时,井下钻柱的第二阶固有频率始终大于第一阶固有频率.该文的研究方法和模型为井下钻柱钻具分析和结果优化提供了理论参考和实际意义.     

Structure and Properties of Nanocrystalline Oxide Powders

The crystalline and porous structure of superfine powders and fibers made of alumina and zirconia doped with yttria is investigated. The particle sizes were determined by the methods of coherent dispersion and scanning transmission electron microscopy. Based on data on the sizes of crystallites of the metal oxides, which were obtained by different methods, it is found that crystalline transformations of the oxides lead to dispersion of the materials. The structural transformations of the superfine oxides are accompanied by changes in crystallite sizes and in the character and size of pores. The laws established allow one to purposefully control the process of producing nanostructured oxide powders and fibers, which can be utilized as active fillers for composite materials based on various matrices. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 6, pp. 831–840, November–December, 2005.     

几何学在卫星精确定位中的应用

卫星轨道及卫星导航定位都涉及很多几何问题,那么怎样用几何学解决卫星轨道及导航定位的计算是在实际应用中面临的一个重要课题.在这个问题基础上,给出了在适合于不同情况下的坐标系的转换公式,主要研究了导航卫星轨道的有效计算,为进行实时导航定位,讨论了卫星的准确定位算法和它的速度、经纬度的确定.最后,对未来的研究方向做出探讨.     

考虑繁忙率的多时段救护车优化布局研究

救护车布局对院前急救服务中需求的响应具有决定性作用。本文重点研究了考虑繁忙率的多时段救护车优化布局问题,在传统双覆盖模型基础上引入救护车繁忙率因素,提出改进后的双覆盖模型。首先计算考虑繁忙率的期望覆盖需求量,进而结合实际,将一天以早晚高峰划分为5个时段,探究不同时段下繁忙率差异带来的不同布局方案。以上海市松江区2014年数据为例,应用改进后的模型进行了系统深入的实证研究,并绘制繁忙率对需求覆盖率的影响曲线。结果表明,本文提出的布局方案比实际方案得到的期望覆盖需求量提高了3.19%,比传统双覆盖模型得到的期望覆盖需求量提高了0.54%,证明了改进后模型的有效性;需求覆盖率曲线随繁忙率增加而下降,与实际意义相符。该方法能够直观简洁地得出救护车布局方案,利于院前急救服务水平的提升,为社会安全提供有力保障。     

一种基于可拓学的电子商务内容推荐算法研究

为研究电子商务内容推荐算法,论文从电子商务推荐系统中的瓶颈问题——相似度计算出发,借助可拓学的方法进行分析。论文将可拓学中基元的表示方法引入推荐算法中,并采用关联函数和可拓距的思想,实现了产品的表示和相似度计算,进而得到了一种新的内容推荐算法。然后通过实例分析对算法进行验证,确认了方法的可靠性和有效性。论文的研究将可拓学思想引入到推荐算法中,这对可拓思想的应用以及推荐算法的实现都起到了有益的作用。     

组织智能与组织生存能力

从宏观的角度，组织具有有机生命物的特征，不但能够对外界环境的变化和刺激能够作出反应。而且还能意识到环境的变化并预先作出某种安排。即，体现出某种智能特性。在激烈的竞争和复杂多变的环境中组织如何能够生存下来并取得发展的问题，一直得到管理科学学的密切关注，也是研究的热点之一。按照复杂科学和当代管理科学的理论，并结合心理科学领域中的一般智能理论，本讨论了组织智能的一些理论基础，初步探讨了组织智能与组织生存的关系。     

基于模糊FNN-ELECTRE法的国有商业银行竞争力评价

随着金融业全方位开放,国有商业银行已成为国家经济命脉的核心,其竞争力强弱关系着国家经济的繁荣与衰退。本文基于模糊FNN-ELECTRE方法建立国有商业银行竞争力评价模型,以因素神经网络理论(FNN)与ELECTRE融合方法为基础,以现有商业银行竞争力评价指标为着眼,把国有商业银行竞争力的评价体系从现实竞争力和潜在竞争力两个因素抽取为一级指标,以规模、质量、业务结构、效率、成长性五个因素设为二级指标。从实证的角度对银行A、银行B、银行C、银行D、银行E五大国有银行进行分析验证,对其属性值进行和谐性与非和谐性检验得出,银行B竞争能力最强,银行E竞争能力最弱,五大国有银行均有改进空间。     

Creep of polymer concrete in the nonlinear region

Two polyester-based polymer concretes with various volume content of diabase as an extender and aggregate are tested in creep under compression at different stress levels. The phenomenological and structural approaches are both used to analyze the experimental data. Common features of changes in the instantaneous and creep compliances are clarified, and a phenomenological creep model which accounts for the changes in the instantaneous compliance and in the retardation spectrum depending on the stress level is developed. It is shown that the model can be used to describe the experimental results of stress relaxation and creep under repeated loading. Modeling of the composite structure and subsequent solution of the optimization problem confirm the possibility of the existence of an interphase layer more compliant than the binder. A direct correlation between the interphase volume content and the instantaneous compliance of the composite is revealed. It is found that the distinction in nonlinearity of the viscoelastic behavior of the two polymer concretes under investigation can be due to the difference in their porosity. Submitted to the 11th International Conference on Mechanics of Composite Materials (Riga, June 11–15, 2000.) Translated from Mekhanika Kompozitnykh Materialov, Vol. 36, No. 2, pp. 147–164, 2000.     

PLF.sets的实证研究及其高质量仿真应用

为高效率与高质量仿真城市人口迁移与演变趋势, 基于Zadeh模糊集的基础知识, 引入哲学否定与计算机逻辑中对立否定、中介否定和矛盾否定的概念。在反复研究和论证了三种逻辑否定之间的内在关系、基本特征和融合条件后, 创新性地提出了PLF.sets泛逻辑性模糊集, 形成可直接参与计算的多种逻辑变量及其演变形式的评价因数集。PLF.sets在饱和验证其运算规则和逻辑转化可行性的前提下, 通过已知局部隶属函数g(x)构建出逼近性能良好的整体隶属度函数f(x)。它能够在确定的值域U[a, b]内, 使得任意的x(x∈U)映射于f(x)值。并在高度仿真和逼近原始系统规律的同时, 逻辑简化系统函数产生的复杂性计算。PLF.Sets于《管理信息系统》教学质量评价的实证研究结果充分证明, PLF.sets方法可以化繁为简, 简化运算方法和步骤;显示出高效性、准确性、普适性和简洁性的特点。PLF.sets方法在对北京城市人口迁移与演变趋势仿真的应用表明:(1)北京城市人口流动变化净增加值的定位均是“多”的等级;(2)北京城市人口流动网络及其关联度特征的定性等级均是“高”级别。最终高质量地评估了正向迁移城市的人口流动格局、人口迁移与演变趋势。     

基于关系契约视角的农户与农产品电子商务企业合作机制演化博弈分析

本文基于关系契约的视角,运用演化博弈理论,构建有限理性特性下的农户与农产品电子商务企业合作演化博弈模型,分析双方合作策略的演进过程、稳定策略及其影响因素,并通过Matlab仿真模拟分析影响双方合作策略选择的因素,验证博弈结果正确性。研究结果表明:农户和农产品电子商务企业选择合作策略与合作投入成本、实现的超额收益密切相关,博弈初始状态、再交易成本、单方不合作获得的收益及违约罚金等因素影响系统的演化稳定结果。因此完善农户与农产品电子商务企业的合作机制,需要构建合理的利益分配机制、良好的关系治理机制、有效的监督和惩罚机制和信息共享、沟通与协调机制。