New properties of the Busemann ellipsea

A combination of the Busemann ellipse, the inscribed unit circle and a circle of radius √2 about the same centre is considered. For supersonic two-dimensional potential gas flows, it is shown that the inclinations of the velocity vector in motion along an arbitrary characteristic, the characteristic itself and the characteristic of the other family have values equal to, respectively. the difference between the areas of the elliptical and circular (R = 1) sectors, the difference between the areas of the elliptical and circular (R = √2) sectors, and the area of the elliptical sector, apart from unimportant multiplicative and additive constants. The straight sides of the sectors in question are the semiminor antis of the ellipse and the radius vector of the velocity. The obvious analogy with one of Ke:pler's laws is pointed out. The existence of a point of intersection of the ellipse and the second circle illustrates a well-known result of Khristianovich concerning the points of inflexion of characteristics with a monotone velocity distribution. It is shown how the combination of the ellipse and the inscribed circle illustrates the simplification of the compatibility conditions and the Darboux equation for trans- and hypersonic flows.     

Optimization of the Relaxation Parameter for S.S.O.R. and A.D.I. Preconditioning

We present and compare several approaches for the optimization of the relaxation parameter both for A.D.I. and S.S.O.R. basic iteration and preconditioning conjugate gradient method. For each kind of preconditioning a detailed link between estimates of the spectral radius of the iteration matrix and of the condition number resulting from preconditioning is proposed. It allows to choose the best approach in order to obtain the optimal relaxation parameter and the corresponding optimal estimates either of the spectral radius of the iteration matrix and of the resulting condition mumber of the S.S.O.R. and A.D.I. preconditioning.     

Tools of the mind: Techniques and methods for intellectual work: V. STIBIC North-Holland,Amsterdam, 1982, xiii + 297 pages,Dfl.85.00

Many location problems may be separated into a series of interrelated macro, meso and micro decision-making states. The macro scale decision determines the type, capacity and number of facilities, the meso scale decision determines the location and allocation of facilities and the micro scale decision determines such considerations as routing and scheduling of service vehicles. This paper concerns the first two levels of decision-making.The present paper demonstrates the use of two models: (i) an analytical model that uses continuum approximations and methods of calculus to determine the number of facilities, the capacity and the approximate location of each that minimizes the sum of the transportation and facility costs for a slowly varying demand rate, and (ii) a traditional location-allocation model that determines more exactly the resulting locations and allocations. These two approaches have specific requirements in terms of data input, cost of data collection and cost of solution and, consequently, yield unique insights and benefits for practising planners. The strengths and weaknesses of the two models are complementary. This thesis is developed with an analysis of the Calgary, Alberta refuse collection and disposal system.     

考虑成员风险态度的零售商资金约束闭环供应链定价与回收决策

针对由制造商、回收商和资金约束的零售商组成的三级闭环供应链,考虑供应链成员面对市场需求不确定时表现出不同的风险态度,研究了闭环供应链的定价与回收决策问题。首先给出了产品的市场需求函数与回收商的回收成本函数;然后基于均值-方差法,构建了各成员和闭环供应链的效用函数;进一步地,依据博弈论的思想,确定了不同渠道权力结构下的最优零售价格、最优回收率和最优批发价格;最后分析了闭环供应链成员风险态度和贷款利率对供应链最优决策和效用的影响。研究表明,成员风险态度和贷款利率能够影响闭环供应链最优决策和效用,其中,风险规避的零售商和制造商对闭环供应链其他成员均有利,但是对自身和闭环供应链不利;风险规避的回收商对闭环供应链成员均不利;贷款利率的增长会降低成员和闭环供应链的效用。     

The thermodynamically consistent equations of a thermoelastic saturated porous medium

A phenomenological model of a porous medium saturated with fluid is considered with in the framework of the hypothesis of interpenetrating continua. Assuming that there are no phase transitions, that the contribution of pulsations to the stress tensor and kinetic energy is small, and the components of the medium are in thermal equilibrium, mass, momentum and energy equations and a law of conservation of compatibility of the deformations and velocities are formulated. Using a representation of the force of interaction of the components in the form of the sum of equilibrium and dissipative components, a new form of inequality is obtained for the rate of entropy production. A definition of a thermoelastic saturated porous medium is given. The symmetry group of such a medium is considered as a set of two groups, corresponding to the symmetry of the skeleton and the fluid. It is shown that, in the class of thermoelastic porous media with an arbitrary type of symmetry of the skeleton, the saturating fluid can only be an ideal fluid, while the thermodynamic potentials and the porosity, stresses and entropies determined by them do not depend on the temperature gradient and the relative fluid velocity. It is found that the condition of incompressibility of only one of the components of the medium leads to the elimination of the porosity from the governing relations, rather than to kinematic limitations. The limitations imposed on the governing relations by the principle of thermodynamic consistency and the requirement of independence of the choice of the frame of reference are investigated. A form of the governing relations, necessary and sufficient to satisfy these principles, is obtained. It is shown that the Biot equations are one of the forms of thermodynamically consistent governing relations. A thermodynamic validation of the effective-stress tensor is given.     

The buckling of a drill string in a curvilinear borehole with axial line imperfections

The problem of the elastic buckling of drill strings in the channels of deep curved boreholes with geometric axial line imperfections is formulated. Imperfections in the form of localized helices are considered. The relation between the forces resisting the motion of the string and the amplitudes, pitches and sites of localization of the imperfections is analysed. The distributed forces of contact and friction interaction between the drill string and the borehole surface are found and the effects of seizure of the drill string are established. It is shown that the resistive forces and their moments increase as the amplitudes of the imperfections increase, and as their pitches and the displacement of the zones where they are relocated from the lower most distorted parts to the upper least distorted parts, decrease.     

基于模糊信息熵理论的港口物流系统竞争能力研究——以福州港智慧物流与低碳港口建设为例

在其深层次机理上,港口物流系统竞争能力必受其物质技术支撑体系的制约．结合智慧港口和第五代港口基本理论,可得出深层次物质技术支撑体系主要有：物质资源禀赋、城市经济系统、物联网系统、港口经营系统、绿色效率系统等．以相关港口物流系统竞争力基本理论为指导,考虑到中国各港口的实际情况,结合数据获得的难易程度,分别从基础设施、发展环境、智慧技术、服务水平、低碳绩效五个方面遴选出18个评价指标,按照模糊信息熵理论,利用全国24个主要港口2001—2013年的原始数据,通过数学软件Matlab编程,计算出系统层指标的信息熵和权重及全国8个代表性港口2013年的竞争能力综合评价值,并以福建省福州港为例,对其进行横向比较和纵向时序分析．     

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。     

Algorithms for partitioning of large routing networks

Partitioning of large networks is vital for decentralized management and control.This paper presents two algorithms called ‘Hierarchical Recursive Progression-1’ (HRP-1) and ‘Hierarchical Recursive Progression-2’ (HRP-2) for partitioning of large networks into subnetworks of limited size with very few interconnections between them. In other words, we are trying to maximize the internal nodes and minimize the external connections of the subnetworks. The restriction on the size and the external connections is obtained by comparison against a user-defined value for the size of the subnetwork and for external connections via a term called density. The density of a subnetwork is defined as the ratio of the number of external connections and the size of the subnetwork. The two algorithms presented in the paper are based on the principle of subnetwork clustering. At the start of the algorithms,the number of subnetworks is equal to the total number of nodes of the network with each subnetwork containing a single node. Later, subnetworks are merged at various runs of the algorithm to form new subnetworks using connectivity,density and size criteria. The algorithms terminate when all the subnetworks satisfy a user-defined size and density limit. The difference between the algorithms HRP-1 and HRP-2 lies in the definition of density of subnetworks and the way through which the subnetworks are grouped at consecutive iterations of the algorithm. Note that the number of nodes inside the subnetworks never violates the size limit, thereby ensuring even distribution of load on the partitions obtained. Finally, the two algorithms are compared and tested on randomly generated graphs and a part of Paris road Network.     

政府奖惩下供应链合作减排与低碳宣传的动态优化

为减少生产过程中碳排放对环境带来的不利影响,考虑到政府对制造商采取奖惩措施,以此为背景,针对供应链长期合作减排、低碳宣传的问题,构建微分博弈模型。考虑到产品需求受碳排放量和零售商低碳宣传努力的共同影响下,得出并分析了分散式和集中式决策下制造商和零售商的反馈均衡策略及产品碳排放量的最优轨迹,发现产品碳排放量的最优轨迹具有多种敛散性,且在集中式决策下实现了供应链利润和环境绩效的双赢。此外,还分析了政府奖惩力度对产品碳排放量的影响。最后结合算例对模型进行分析,为供应链的低碳化管理和政府奖惩政策的制定提供了理论参考。     

投资者情绪和市场利率对证券市场指数收益影响特点的动态刻画

本文基于2006年10月到2015年6月市场层面的投资者情绪和上证综指收益率,刻画了投资者情绪和市场利率对证券市场指数收益率的影响。首先,本文通过误差修正模型研究了短期层面投资者情绪对证券市场收益的影响特点,补充了以往在长期层面和整体收益水平上投资者情绪对市场收益影响的研究。由于市场层面的投资者情绪会受到宏观政策影响,之后本文将市场利率作为政策因素,通过分位数回归分析了不同市场收益水平下,市场利率和剔除了宏观政策因素的投资者情绪对市场收益的影响。研究结果表明:投资者情绪和证券市场收益之间的关系在短期层面上更为显著;当我国的证券市场环境处于“牛市”时,市场利率和投资者情绪均会对证券市场指数收益产生显著的影响,且随着市场收益水平的逐步上升,市场利率的反向作用和投资者情绪的正向作用均会逐渐加强。     

Model-companions and definability in existentially complete structures

The theory of model-companions and existentially complete structures is both reviewed and developed further. The review begins with A. Robinson’s work in the fifties and continues through the definability of second order structures in existentially complete groups. New results include necessary and sufficient conditions for the existence of a model-companion in terms of the definability of general elementary properties. The main theorem of the paper gives necessary and sufficient conditions for the existence of a model-companion for universal theories with finite presentations and the amalgamation property. This result generalizes the result of P. Eklof and G. Sabbagh that the theory ofR-modules has a model-completion if and only ifR is coherent. The author’s survey presentation at the Robinson Memorial Conference included the material in the first and fourth sections of this paper and Theorem 1 and its corollaries and examples in the second section. The other results in Section 2 and the results in Section 3 were obtained after the conference.     

基于物元分析的科技人才考评研究

利用可拓学中的物元分析理论,对科技人才考评问题进行了研究.在分析多种相关因素的基础上,从基本素质、学术素质、业务素质和业绩贡献等方面构建了科技人才考评指标体系.对考评指标实行规范化、科学化、定量化的基础上,建立了科技人才考评的物元分析模型.最后应用结果表明,把物元分析理论应用于科技人才考评是可行的,同时,物元分析拓展科技人才考评的研究途径.     

企业及市场经营效用函数形式研究

鉴于经营效用是企业制订战略决策和发展策略的重要影响因素,研究其基本效用类型,提出对应的函数形式,并在此基础上提出市场总体的综合经营效用测度方法。企业经营效用由自身经营效用和同业比较效用两部分线性合成,效用变量分别为企业单位盈利指标加权合成值及单位盈利水平与行业平均值的差,效用函数通过原点且单调,因此需将效用理论中对应于各种效用类型的对数函数、指数函数等进行坐标变换、旋转或对称。保守型和冒险型效用在定义域内分别为凹函数和凸函数,共组合为9种效用类型含81种基本函数形式,并给出各效用类型含义、经营特征和定价倾向。以市场份额作为各企业经营效用权重,构建幂平均效用合成模型作为市场总体综合经营效用测度。     

The harmonic oscillations of a viscoelastic rod of triangular cross-section

Two exact solutions of the plane strain problem of the harmonic oscillations of a viscoelastic rod, the cross-section of which is a right triangle, are proposed. Either the normal displacement and the shear stress or the shear displacement and the normal stress of the side surface of the rod are given. Six dimensionless parameters which affect the dynamic deformation process are derived. Two parameters characterize the contribution of the viscous properties with respect to the elastic properties, two others define the logarithmic decrement of the longitudinal and shear harmonic waves, and two other parameters affect the wavelength of the corresponding wave and the velocity of motion of the wave front of these waves. The velocities of both types of waves and their wavelengths turn out to be greater than the velocities and wavelengths of the corresponding elastic waves. It is shown that, for certain values of the viscosity and the oscillation frequency, pseudo-resonance frequencies are possible which are higher than the resonance frequencies for an elastic medium.     

Multivariate analysis for the assessment of factors affecting industrial competitiveness: The case of Greek food and beverage industries

Principal component analysis is integrated with canonical analysis to examine aspects of the competitiveness of two different sectors of the Greek manufacturing, i.e. the food and the beverage industries. Different measures of labour productivity, vertical integration, technological innovation and size of the firms which are considered as critical factors of industrial competitiveness are used in the application of the principal component analysis. Canonical analysis is then applied to correlate the variables of labour productivity with the other variables. In the case of the food and beverage integrated sector, the results of the principal component analysis pinpoint that there are two main principal components: (a) labour productivity and vertical integration, and (b) technological innovation and size. The first factor depicts the internal organizational, structural and production processes changes realized so that the competitiveness of the sector firms improves, whereas the second factor reflects the response of the sector to technological and growth trends. The two variables of labour productivity are affected by the degree of vertical integration and, at a lesser degree, by a common factor of the size of the firm and the level of investment for technological innovation. Copyright © 2000 John Wiley & Sons, Ltd.     

Time-linearized,compact methods for the inviscid GRLW equation subject to initial Gaussian conditions

The objective of this paper is three-fold. First, four time-linearization methods that are second- and fourth-order accurate in time and space, respectively, are presented and used to study the dynamics of the modified and generalized regularized-long wave equations (mRLW and GRLW equations, respectively). Two of the methods use the conservation-law form of the equations and treat the wave amplitude and its second-order spatial derivative and the linear and nonlinear advection fluxes as unknowns, whereas the other two employ the non-conservation-law form of the equations and consider the wave amplitude and its first- and second-order spatial derivatives as unknowns. The methods employ three-point fourth-order accurate Padé discretizations for the first- and second-order derivatives, are second-order accurate in time, and yield linear systems of blocktridiagonal matrices. Second, the accuracy of these methods is assessed by comparing their results with those of the exact solution of the mRLW equation. It is reported that the four methods predict nearly the same values of the three invariants and have the same accuracy, and that an accurate prediction of the invariants may not correspond to small errors in space and time. Third, the dynamics of the inviscid GRLW equation is studied first qualitatively in terms of length and time scales and then numerically as a function of the linear advection speed, the exponent of the nonlinear advection flux, the dispersion coefficient and the amplitude and width of the initial bell-shaped or Gaussian conditions. It is shown that wide initial conditions result in wave steepening and breakup and the formation of solitary waves whose amplitude and speed decrease as the time for their formation increases. For narrow initial conditions, it is shown that only a single solitary wave may form. Behind this wave and depending on the parameters that characterized the inviscid GRLW equation, rarefaction or negative amplitude waves that propagate towards the upstream boundary or a train of localized oscillatory waves that do not emerge from the trailing edge of the leading solitary wave may be formed. These oscillatory waves exhibit the characteristics of, but are not dispersive shock waves and their amplitude and frequency increases as the width of the initial conditions is decreased. The results presented here do not only complement previous work by the authors, they also show that the dynamics of the inviscid GRLW equation undergoes new and interesting phenomena as the width of the initial conditions is decreased.     

低碳环境友好技术政产学研金协同创新演化博弈研究

在气候变化应对日益紧迫的背景下,研究了政府、企业、研发机构和金融机构(政产学研金)参与低碳环境友好技术(LCEFT)创新的条件和策略。以企业合作关系为假设条件,引入金融主体和科研机构,构建了LCEFT的政产学研金协调创新博弈模型,深入分析了碳权质押、信用等级、投资回报等因素对博弈系统群体协调创新策略的影响。研究表明,金融机构参与协同创新的决策受到政府奖惩机制、绿色信贷项目盈利和风险等因素的影响;多主体在资源和能力上的互补性正是LCEFT协同创新联盟形成的关键;政府部门的奖惩机制能够促进多主体合作,但难以使得整体获得最优,达到整体最优的关键是有效地发挥政府部门的引导作用和金融机构的杠杆作用。本文为政府部门制定绿色金融、产学研协同创新及产业化管理机制提供了新思路和一定的决策参考。     

Optimal Mixed Batch Shipment Policy with Variable Safety Factor for the Single-Vendor Single-Buyer Production-Inventory System

This study investigates the production and inventory problem involving stochastic demand in a single-vendor single-buyer integrated system. The stochastic model is constructed and is controlled by both the reorder and shipping points with mixed geometric and equal batch shipment policy and variable safety factor. The minimum cost model is transformed into the maximum order quantity model. Consequently, the structure of mixed geometric and equal shipments can easily be obtained. The structure of the mixed geometric and equal shipments comprises number of batches, number of geometric shipments, and ratio of equal sized shipments to the size of the first shipment. The problem is solved using the proposed algorithm that determines the economic lot size, the structure of the mixed geometric and equal shipments, and the safety factor. An illustrative example demonstrates the effectiveness of the algorithmic procedures.