水资源可再生能力综合评价的遗传加权物元模型

为了科学地计算水资源可再生能力评价指标的权重 ,使评价方法具有可操作性 ,采用主、客观相结合的赋权基点法 ,以全局收敛的格雷码加速遗传算法为工具来确定权重 ,并结合物元分析理论 ,建立了一种新的评价模型——遗传加权物元模型 .文中给出了该模型实施的详细步骤 ,对黄河流域 9个行政分区的水资源可再生能力进行了综合评价 ,取得了较好的效果 .     

Testing Ten Theories

Using the most comprehensive data set now available, this investigation tests the precision of all exchange theories that now contend. Beyond precision, the investigation focuses on broad issues of effectiveness including consistency, parsimony, and whether the theories can be applied to structures larger than normally studied in the lab. Seeking greater parsimony, this investigation introduces a new model by combining parts of two contending theories. We find that all ten theories have scientific merit for all can predict with some effectiveness for the exchange structures experimentally investigated. Nevertheless, the ten vary in precision. Elementary Theory is the most precise. The new Expected-value Resistance model ranks second in precision and is the simplest. Both apply to large networks as well as the best of the other theories.     

Network DEA model for supply chain performance evaluation

This paper constructs an alternative network DEA model that embodies the internal structure for supply chain performance evaluation. We take the perspective of organization mechanism to deal with the complex interactions in supply chain. Three different network DEA models are introduced under the concept of centralized, decentralized and mixed organization mechanisms, respectively. Efficiency analysis including the relationship between supply chain and divisions, and the relationship among the three different organization mechanisms are discussed. As a further extension, we investigate internal resource waste in supply chain.     

多阶段并发的协同物流网络任务-资源集成调配模型

协同物流网络作为动态开放的网络需要整合多种资源,以完成多项并行的物流任务。为此,本文从物流服务集成商的角度,研究了带时间窗和资源约束的任务—资源集成调配问题。通过将物流任务分解为不同阶段,构造多阶段并发的协同物流网络任务—资源集成调配模型,并采用遗传算法对模型进行求解,以从候选资源集合中为任务阶段匹配合适的资源。算例结果表明,该模型能够有效实现N-N的任务-资源集成调配,使得协同物流网络的整体效益达到最优。     

Interpretability degrees of finitely axiomatized sequential theories

In this paper we show that the degrees of interpretability of finitely axiomatized extensions-in-the-same-language of a finitely axiomatized sequential theory—like Elementary Arithmetic EA, IΣ₁, or the Gödel–Bernays theory of sets and classes GB—have suprema. This partially answers a question posed by ?vejdar in his paper (Commentationes Mathematicae Universitatis Carolinae 19:789–813, 1978). The partial solution of ?vejdar’s problem follows from a stronger fact: the convexity of the degree structure of finitely axiomatized extensions-in-the-same-language of a finitely axiomatized sequential theory in the degree structure of the degrees of all finitely axiomatized sequential theories. In the paper we also study a related question: the comparison of structures for interpretability and derivability. In how far can derivability mimic interpretability? We provide two positive results and one negative result.     

Noncommutative geometry and spacetime gauge symmetries of string theory

We illustrate the various ways in which the algebraic framework of noncommutative geometry naturally captures the short-distance spacetime properties of string theory. We describe the noncommutative spacetime constructed from a vertex operator algebra and show that its algebraic properties bear a striking resemblence to some structures appearing in M Theory, such as the noncommutative torus. We classify the inner automorphisms of the space and show how they naturally imply the conventional duality symmetries of the quantum geometry of spacetime. We examine the problem of constructing a universal gauge group which overlies all of the dynamical symmetries of the string spacetime. We also describe some aspects of toroidal compactifications with a light-like coordinate and show how certain generalized Kac—Moody symmetries, such as the Monster sporadic group, arise as gauge symmetries of the resulting spacetime and of superstring theories.     

Sequential Gaussian simulation vs. simulated annealing for locating pockets of high-value commercial trees in Pennsylvania

A continuous map of a forest resource is useful to visualize patterns not evident with point samples or as a layer in a geographic information system. Forest resource information is usually collected by ground inventories using point sampling, aerial photography, or remote sensing. Point sampling is expensive and time consuming. Less expensive aerial photography and remote sensing cannot provide the required detail. The tools of geostatistics can provide estimates at unsampled locations to create a continuous map of the forest resource. Two sequential simulation techniques, sequential Gaussian simulation and simulated annealing, are compared for locating pockets of high-value commercial trees in Pennsylvania. Both procedures capture the same trends, but simulated annealing is better than sequential Gaussian simulation at finding pockets of high-value commercial trees in Pennsylvania. Sequential Gaussian simulation is better at visualizing large-scale patterns and providing a quick solution. Simulated annealing requires more user time and should be used for projects requiring local detail.     

Performance analysis and design of supply chains: a Petri net approach

In this paper, we investigated a dynamic modelling technique for analysing supply chain networks using generalised stochastic Petri nets (GSPNs). The customer order arrival process is assumed to be Poisson and the service processes at the various facilities of the supply chain are assumed to be exponential. Our model takes into account both the procurement process and delivery logistics that exist between any two members of the supply chain. We compare the performance of two production planning and control policies, the make-to-stock and the assemble-to-order systems in terms of total cost which is the sum of inventory carrying cost and cost incurred due to delayed deliveries. We formulate and solve the decoupling point location problem in supply chains as a total relevant cost (sum of inventory carrying cost and the delay costs) minimisation problem. We use the framework of integrated GSPN-queuing network modelling—with the GSPN at the higher level and a generalised queuing network at the lower level—to solve the decoupling point location problem.     

煤炭资源资产分类方法比较研究

煤炭资源资产评估是实行煤炭资源资产化管理的重要基础工作 ,而煤炭资源资产分类的可靠性是有效完成这一工作的前提条件 .针对煤炭资源资产的特点 ,建立了多个分类模型——基于模糊聚类的分类模型、基于 BP网络的分类模型及基于自适应共振理论网络的分类模型 ,编制了相应的分类程序软件包 ,实例运行效果证明了模型的有效性 .文中还对所建模型进行了比较和分析 ,提出了具体应用的建议 .     

Snarks with given real flow numbers

We show that for each rational number r such that 4<r?5 there exist infinitely many cyclically 4‐edge‐connected cubic graphs of chromatic index 4 and girth at least 5—that is, snarks—whose flow number equals r. This answers a question posed by Pan and Zhu [Construction of graphs with given circular flow numbers, J Graph Theory 43 [2003], 304–318]. © 2011 Wiley Periodicals, Inc. J Graph Theory 68: 189‐201, 2011     

Who You Know vs. What You Know: The Impact of Social Position and Knowledge on Team Performance

Organizational behavior theories generally agree that human capital is critical to teams and organizations, but little guidance exists on the extent to which such theories accurately explain the relative contributions of individual actors to overall performance. Using newly created network measures and simulations based on data obtained from a software development firm, we investigate the relative effectiveness of social network theory and resource dependency theory as predictors of individuals' contributions to team performance. Our results indicate that individual impacts on team performance are more closely associated with knowledge and task dimensions than with social network structure. Furthermore, given that knowledge may be assessed a priori, these factors provide useful guidance for structuring teams and predicting team performance.     

Network interdiction to minimize the maximum probability of evasion with synergy between applied resources

In this paper, we model and solve the network interdiction problem of minimizing the maximum probability of evasion by an entity traversing a network from a given source to a designated terminus, while incorporating novel forms of superadditive synergy between resources applied to arcs in the network. Inspired primarily by operations to coordinate Iraqi and U.S. security forces seeking to interdict an evader attempting to avoid detection while transiting part of the nearly rectilinear street network in East Baghdad, this study motivates and examines either linear or concave (nonlinear) synergy relationships between the applied resources within our formulations. We also propose an alternative model for sequential overt and covert deployment of subsets of interdiction resources, and conduct theoretical as well as empirical comparative analyses between models for purely overt (with or without synergy) and composite overt-covert strategies to provide insights into absolute and relative threshold criteria for recommended resource utilization. Our empirical results confirm the value of tactical patience regarding decisions on the covert utilization of resources for network interdiction. Furthermore, considering non-integral and integral resource allocations, we identify (theoretically and empirically) parametric characteristics of instances that exhibit the relative worth of employing partially covert operations. Under the relatively more practical scenario involving integral resource allocations, we demonstrate that the composite overt-covert strategy of deploying resources has a greater potential to improve over a purely overt resource deployment strategy, both with and without synergy, particularly when costs are positively correlated, resources are plentiful, and a sufficiently high ratio of covert to overt resources exists. Moreover, should an interdictor be able to ascertain an optimal evader path, the potential and magnitude of this relative improvement for the overt-covert resource allocation strategy is significantly greater.     

Network DEA pitfalls: Divisional efficiency and frontier projection under general network structures

Data envelopment analysis (DEA) is a method for measuring the efficiency of peer decision making units (DMUs). Recently network DEA models been developed to examine the efficiency of DMUs with internal structures. The internal network structures range from a simple two-stage process to a complex system where multiple divisions are linked together with intermediate measures. In general, there are two types of network DEA models. One is developed under the standard multiplier DEA models based upon the DEA ratio efficiency, and the other under the envelopment DEA models based upon production possibility sets. While the multiplier and envelopment DEA models are dual models and equivalent under the standard DEA, such is not necessarily true for the two types of network DEA models. Pitfalls in network DEA are discussed with respect to the determination of divisional efficiency, frontier type, and projections. We point out that the envelopment-based network DEA model should be used for determining the frontier projection for inefficient DMUs while the multiplier-based network DEA model should be used for determining the divisional efficiency. Finally, we demonstrate that under general network structures, the multiplier and envelopment network DEA models are two different approaches. The divisional efficiency obtained from the multiplier network DEA model can be infeasible in the envelopment network DEA model. This indicates that these two types of network DEA models use different concepts of efficiency. We further demonstrate that the envelopment model’s divisional efficiency may actually be the overall efficiency.     

Comparing material and structural set theories

We study elementary theories of well-pointed toposes and pretoposes, regarded as category-theoretic or “structural” set theories in the spirit of Lawvere's “Elementary Theory of the Category of Sets”. We consider weak intuitionistic and predicative theories of pretoposes, and we also propose category-theoretic versions of stronger axioms such as unbounded separation, replacement, and collection. Finally, we compare all of these theories formally to traditional membership-based or “material” set theories, using a version of the classical construction based on internal well-founded relations.     

关于数学哲学的新思考

本文以计算机软件 ,程序语言等作类比 ,提出数学命题是一种“概念实在”,以阐明数学对象的本体论地位 ;并根据自然科学只能基于现有的数学理论而建构这一事实 ,对数学在自然科学中的超前性和有效性作出了新的解释 .同时 ,本文勾划了一种新的数学哲学的轮廓 ,它以数学中引入新结构 ,提出猜想等创造性活动为课题 ,以数学史材料研究为方法 ,以探求数学发展的内在统一性为目的 .     

Models for cellular manufacturing systems design: matching processing requirements and operator capabilities

Cellular manufacturing systems comprise categorizing machines used in the firm's production system into cells dedicated to part families that have similar requirements in terms of tooling, setups and operations sequences. Although worker assignment to cells has a significant impact on cell effectiveness, scant attention has been paid to this issue in previous research. We present two models—sequential and concurrent—for cell formation. The sequential model uses a machine–part incidence matrix (MPIM)-based similarity coefficient while the concurrent model uses a similarity coefficient based on both MPIM and machine–operator incidence matrix (MOIM). Our results show that for 50 problem sets widely reported in literature, the concurrent model outperformed the sequential model in most cases. A measure quantifying the difference in MPIM and MOIM was developed and the relative out-performance of the concurrent model was shown to depend on the value of this measure.     

The unprovability of small inconsistency

Summary We show that a consistent, finitely axiomatized, sequential theory cannot prove its own inconsistency on every definable cut. A corollary is that there are at least three degrees of global interpretability of theories equivalent modulo local interpretability to a consistent, finitely axiomatized, sequential theory U.     

Time series modeling of Army Mission Command communication networks: an event-driven analysis

We examine the communication time series of a fully-networked Army coalition command and control organization. The network comprised two echelons of command, at the Division and Brigade levels, over a 2-week military scenario exercise involving a Mission Command staff communicating over email and phone. We used time series analysis to predict the communications record based on an external work variable of the number of important scenario events occurring across time. After taking into account structural features of the time series—decreasing communications over time, a network crash, and the transition between weeks—we examined the remaining variability in email and phone communication. We found that the exercise scenario events were not a significant predictor of the Divisional communications, which were best fit by an auto-regressive model of order 1, meaning that the best predictor of the volume of communications at a given time point was the volume of communications on the immediately preceding time point. The occurrence of scenario events, however, did predict the Brigade communication time series, which were well fit by a lag dependent variable model. These results demonstrate that Brigade communications responded to and could be predicted by battlefield events, whereas the Division communications were only predicted by their own past values. These results highlight the importance of modeling environmental work events to predict organizational communication time series and suggest that network communications are perhaps increasingly dependent upon battlefield events for lower echelons of command closer to the tactical edge.     

On the strong circular 5‐flow conjecture

The Strong Circular 5‐flow Conjecture of Mohar claims that each snark—with the sole exception of the Petersen graph—has circular flow number smaller than 5. We disprove this conjecture by constructing an infinite family of cyclically 4‐edge connected snarks whose circular flow number equals 5. © 2006 Wiley Periodicals, Inc. J Graph Theory