基于产品生命周期的闭环供应链定价和协调策略研究

研究产品生命周期条件下一个制造商、一个零售商组成的闭环供应链的定价和协调策略:制造商第一周期只生产新品,从第二周期开始生产再制造品,并负责回收。建立了两周期、多周期和无限周期下的分散决策模型和多周期下的集中决策模型,得到最优定价和生产策略。结果表明:两周期中,制造商和零售商应根据不同的成本节约额制定不同的批发价、零售价和生产量。多周期中,当成本节约额比较小时,除第一和最后一个周期外,制造商和零售商应采取相同的定价和生产策略;当成本节约额比较大时,除第一和最后两个周期外,制造商和零售商应采取相同的定价和生产策略。无限周期中,除第一周期以外,制造商和零售商都应该采取相同的定价和生产策略。在有限周期情况下,制造商和零售商应通过在前期制定比较低的批发价和零售价,以提高生产量和销售量,使得后期的回收量增大,达到降低成本的目的。通过引入收益共享契约制定合适的批发价和销售收入及再制造收益共享比率可以协调整个闭环供应链。算例验证了上述结论。     

不确定同时取送货车辆路径问题及粒子群算法研究

研究了不确定同时取送货车辆路径问题(VRPSPD),考虑运行环境的不确定性,顾客时间窗口要求和对顾客同时进行取货和送货服务的情况,以运作成本最低和顾客满意度最高为决策目标,构建不确定VRPSPD数学模型。模型中,引入模糊随机理论来描述决策环境中的双重不确定性,假定顾客需求量(送货量)和取货量是模糊随机变量。随后,提出基于模糊随机算子的改进粒子群算法对模型进行求解。为了适应模型特点和提高算法效率,设计合理的编码和解码过程,制定多个适应度函数方案处理多目标问题,并应用更加科学的更新策略。最后在应用案例中,通过参数测试获取合理的算法参数取值,采用计算结果分析和求解算法测评验证模型和算法的有效性。     

基于工期-成本综合效用最大的关键链项目缓冲确定

为提高关键链中工期和成本的综合效用,研究一种基于关键链工期和成本进行双目标优化的缓冲确定方法。首先,该方法考虑项目不同工序间工期和成本之间的关系,并基于工期和成本的风险暴露度确定权重,解决不同工序间工期和成本偏好难以量化的问题;其次,根据权重多效用函数对工期和成本进行归一化处理,并确定综合效用最大情况下不同工序的最佳工期;最后基于尾部集中法确定项目缓冲。通过蒙特卡洛模拟实验,将此方法提取缓冲后的项目实际综合效用与传统方法进行比较。比较结果显示,该方法极大地提高项目中工期和成本的综合效用,并且对项目工期和成本均形成更有效的保护。     

房地产业对中国经济真的那么重要吗？

为恰当评估房地产业对中国经济的重要性,通过编制2002、2007和2012年中国社会核算矩阵,进行乘数分解和结构化路径分析的结果表明:房地产业对行业总产出、劳动力和资本报酬、居民和企业收入的拉动作用极低。房地产业主要对金融业、租赁和商务服务业、建筑业以及金属冶炼与压延加工业四个行业的产出影响比较显著,对前三个行业主要是直接的一步式影响,与房地产业紧密相关的产业链条并不长。房地产业对要素报酬和机构收入的拉动总效应极小,且主要是开环效应,与此同时,房地产业主要通过自身和金融业影响要素报酬进而影响机构收入,特别是对资本报酬和企业收入的影响简单、直接,高度依赖这两条基础路径。土地出让金和房地产有关税收已成为地方政府的主要收入来源。房地产开发和运营商、金融机构和地方政府已成为房地产业发展过程中最主要的利益相关方。     

基于马尔可夫更新过程的多阶段冲击退化系统可靠性分析

系统所遭受的冲击和退化损害过程广泛存在着多阶段特征和相互依赖关系,为了更精确建模和分析系统冲击和退化间的依赖性,论文建立了多阶段冲击和退化过程的复合模型,提出了一种更加广义的冲击和退化过程依赖关系,即二者同时对系统损害累积过程产生贡献,进而导致系统阶段的改变,而状态转移又反馈性地影响冲击和退化过程。通过构造马尔可夫更新过程,基于半马尔科夫核,得到此类冲击退化模型的可靠度解析表达。     

随机产出环境下联产品的产量及价格策略研究

基于制造商生产主产品的过程中会随机产出两类存在替代关系的副产品的联产品系统,采用清仓定价模型,研究了不同需求函数(线性需求和指数需求)下,制造商对于主产品和副产品的最优产量与定价策略。通过两阶段优化模型的建立和求解,确定了主产品的最优产量和价格。借助数值分析,归纳出产品替代度和产出波动性对最优产量和利润的影响。研究结果表明,随着产品替代度的增加,制造商的产量上升;随着波动性的增加,制造商的产量下降。最后,将模型扩展到市场非出清的情况,并得出制造商的最优生产决策。     

Size-Dependent Effects of Micro-Nano Mindlin Plates Based on the Couple Stress Theory北大核心CSCD

基于偶应力理论,建立了适用于微纳米结构的Mindlin板理论。考虑横向剪切变形和材料的尺度效应并引入长度尺寸参数,推导了各向同性微纳米Mindlin板的本构方程。根据板的平衡条件,进一步推导出用位移函数和转角函数表示的板的屈曲和振动控制方程。通过对位移和转角变量进行空间和时间域上的分离,得出了四边简支（SSSS）和对边简支、对边固支（SCSC）两种边界情况下微纳米板的屈曲和振动问题的解析解。然后利用MATLAB软件进行算例分析,获得了不同尺寸参数、长宽比、厚长比等情况下板的临界屈曲荷载和固有频率。研究结果与已有文献中的结果以及ABAQUS有限元仿真解进行对比,结果表明,不同参数下的三种方法得到的结果均十分接近。算例分析发现,尺度效应对屈曲载荷和固有频率都有显著影响。     

京瓷与海尔管理模式比较

京瓷的阿米巴经营和海尔推行的自主经营体的思想,都是最大限度地发挥员工的创造力和积极性,是对传统管理的一种颠覆。 在如今的时代,技术创新并不是最重要的,管理创新才是最重要的。日本京瓷和中国海尔的实践充分说明了这个道理。这两家公司生产的产品,在技术上和同行业其他公司并没有显著的差距，之所以企业的效益不一样，是因为管理上的创新。     

考虑无缺陷退货的在线商品信息发布策略

消费者网络购物面临的不确定性往往导致非质量原因的退货。合理发布产品信息,并提供退货保障,是网络零售商促进消费者购买和提高利润的有效策略。基于消费者效用理论和博弈论,构建了产品信息影响消费者购买和退货模型,研究了零售商在垄断和竞争情形下的产品信息发布决策问题,发现垄断性零售商的最优信息发布策略和竞争性零售商在发布产品信息量和信息内容方面的均衡策略均取决于产品价值和退货成本特征,提出了不同市场结构下基于产品特征的在线商品信息发布策略。     

浅水回流的混合有限分析解

混合有限分析法是一种在局部矩形单元上进行离散的数值格式,为了适应非规则边界,建立了Sigma坐标系的浅水回流数学模型。采用1)风引起的回流,2)密度驱动的回流,3)假潮,来检验数学模型和数值方法。计算结果和相应的分析解的比较表明模型和方法是可行的有效的。该技术可用于近海水域的水流和水质的数值模拟。     

Asymptotic behavior for the Navier-Stokes equations with nonzero external forces

We estimate the asymptotic behavior for the Stokes solutions, with external forces first. We found that if there are external forces, then the energy decays slowly even if the forces decay quickly. Then, we also obtain the asymptotic behavior in the temporal-spatial direction for weak solutions of the Navier-Stokes equations. We also provide a simple example of external forces which shows that the Stokes solution does not decay quickly.     

Elastic modulus of a nonpolar polymer

A theoretical calculation of the elastic modulus of a nonpolar polymer (polyethylene) is carried out after deriving the appropriate relationships. Intramolecular forces (retarded rotation) play a far more important part than intermolecular forces. A simple method is proposed for finding the entropy and energy forces from the corresponding elastic moduli. The intra- and intermolecular energy effects are separated for one particular case.K. D. Ushinskii Yaroslav State Pedagogical Institute. Translated from Mekhanika Polimerov, Vol. 9, No. 3, pp. 450–454, May–June, 1973.     

Plastic limit analysis and optimum design of structures for uncertain conditions.

At the application of the plastic analysis and design methods the control of the plastic behaviour of the structures is an important requirement. Since the plastic limit analysis provides no information about the magnitude of the plastic deformations and residual displacements accumulated before the adaptation of the structure, therefore complementary strain energy of the residual forces could be considered an overall measure of the plastic performance of structures and the plastic deformations should be controlled by introducing a bound for magnitude of this energy. If the design uncertainties (manufacturing, strength, geometrical) are expressed by the calculation of the complementary strain energy of the residual forces a reliability based extended plastic limit design problem is formed. In this research, due to the uncertainties the bound for the complementary strain energy of the residual forces is given randomly and a general approach to evaluate the limit load capacity of structures for uncertain conditions is presented. The aim of this study is to evaluate limit load capacity of structures with limited residual strain energy on the probabilistically given conditions. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fracture Mechanics of Rubber Material

This contribution presents an approach based on the material force method which allows to evaluate the fracture sensitivity of rubber material. In order to account for the rate–independent dissipation of filled elastomers subjected to low rates, an endochronic plasticity formulation is introduced. It is shown how configurational forces under consideration of material body forces correspond with the elastic and dissipative energy and how they can be related to energy release rates measured in test configurations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Extremum property of constraint reactions

The problem of finding constraint reactions in mechanical systems is discussed. It is shown that in a number of cases its solution reduces to finding the minimum of the generalized potential energy, whose expression depends on the active forces and the inertial forces and includes the strain energy. The condition of a minimum value provides a means, in particular, to single out “the most realistic” solution of statically indeterminate problems. In systems with Coulomb static friction, verification of the equilibrium conditions can be reduced to a convex minimization problem. Typical expressions for the generalized potential energy in systems with kinetic friction with one bilateral or unilateral constraint, which enable the dynamics of the system to be determined in cases of indeterminancy, are presented.     

Modelling the role of cell-cell adhesion in the growth and development of carcinomas

In this paper, a mathematical model is presented to describe the evolution of an avascular solid tumour in response to an externally-supplied nutrient. The growth of the tumour depends on the balance between expansive forces caused by cell proliferation and cell-cell adhesion forces which exist to maintain the tumour's compactness. Cell-cell adhesion is incorporated into the model using the Gibbs-Thomson relation which relates the change in nutrient concentration across the tumour boundary to the local curvature, this energy being used to preserve the cell-cell adhesion forces.

Our analysis focuses on the existence and uniqueness of steady, radially-symmetric solutions to the model, and also their stability to time-dependent and asymmetric perturbations. In particular, our analysis suggests that if the energy needed to preserve the bonds of adhesion is large then the radially-symmetric configuration is stable with respect to all asymmetric perturbations, and the tumour maintains a radially-symmetric structure—this corresponds to the growth of a benign tumour. As the energy needed to maintain the tumour's compactness diminishes so the number of modes to which the underlying radially-symmetric solution is unstable increases—this corresponds to the invasive growth of a carcinoma. The strength of the cell-cell bonds of adhesion may at some stage provide clinicians with a useful index of the invasive potential of a tumour.     

The influence of dissipative and constant forces on the form and stability of steady motions of mechanical systems with cyclic coordinates

Mechanical systems with cyclic coordinates subject to dissipative forces with complete dissipation and constant forces applied only to the cyclic variables are considered. Problems of the existence of steady motions in such systems and the conditions for their stability are discussed. It is shown, in particular, that if the Rayleigh function is proportional to the kinetic energy, the stability conditions for the steady motions of the system are the same as or (under certain assumptions) similar to such conditions for steady motions of a corresponding conservative system. The example of a physical pendulum is used to show that such conclusions are generally false: dissipative and constant forces may cause destabilization of stable motions of the system.     

Asymptotic solutions of Lagrangian systems with gyroscopic forces

We consider Lagrangian systems in the presence of nondegenerate gyroscopic forces. The problem of stability of a degenerate equilibrium pointO and the existence of asymptotic solutions is studied. In particular we show that nondegenerate gyroscopic forces in general have, at least formally, a stabilizing effect whenO is a strict maximum point of the potential energy. It turns out that when we switch on arbitrary small nondegenerate gyroscopic forces, a bifurcation phenomenon arises: the instability properties ofO are transferred to a compact invariant set which collapses atO when the gyroscopic forces are switched off.Work supported by Russian Fund of Basic Research, the Italian Research Council (CNR) and the Italian Ministery of University (MURST)     

Energy balance invariance for interacting particle systems

This paper studies the principle of invariance of balance of energy and its consequences for a system of interacting particles under groups of transformations. Balance of energy and its invariance is first examined in Euclidean space. Unlike the case of continuous media, it is shown that conservation and balance laws do not follow from the assumption of invariance of balance of energy under time-dependent isometries of the ambient space. However, the postulate of invariance of balance of energy under arbitrary diffeomorphisms of the ambient (Euclidean) space, does yield the correct conservation and balance laws. These ideas are then extended to the case when the ambient space is a Riemannian manifold. Pairwise interactions in the case of geodesically complete Riemannian ambient manifolds are defined by assuming that the interaction potential explicitly depends on the pairwise distances of particles. Postulating balance of energy and its invariance under arbitrary time-dependent spatial diffeomorphisms yields balance of linear momentum. It is seen that pairwise forces are directed along tangents to geodesics at their end points. One also obtains a discrete version of the Doyle–Ericksen formula, which relates the magnitude of internal forces to the rate of change of the interatomic energy with respect to a discrete metric that is related to the background metric.