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321.
Roger D. H. Warburton 《Production and Operations Management》2004,13(2):150-160
The Bullwhip Effect is problematic: order variability increases as orders propagate along the supply chain. The fundamental differential delay equations for a retailer's inventory reacting to a surge in demand are solved exactly. Much of the rich and complex inventory behavior is determined by the replenishment delay. The analytical solutions agree with numerical integrations and previous control theory results. Managerially useful ordering strategies are proposed. Exact expressions are derived for the retailer's orders to the manufacturer, and the Bullwhip Effect arises naturally. The approach is quite general and applicable to a wide variety of supply chain problems. 相似文献
322.
Falk Hüffner Nadja Betzler Rolf Niedermeier 《Journal of Combinatorial Optimization》2010,20(4):335-360
Polynomial-time data reduction is a classical approach to hard graph problems. Typically, particular small subgraphs are replaced by smaller gadgets. We generalize this approach to handle any small subgraph that has a small separator connecting it to the rest of the graph. The problem we study is the NP-hard Balanced Subgraph problem, which asks for a 2-coloring of a graph that minimizes the inconsistencies with given edge labels. It has applications in social networks, systems biology, and integrated circuit design. The data reduction scheme unifies and generalizes a number of previously known data reductions, and can be applied to a large number of graph problems where a coloring or a subset of the vertices is sought. To solve the instances that remain after reduction, we use a fixed-parameter algorithm based on iterative compression with a very effective heuristic speedup. Our implementation can solve biological real-world instances exactly for which previously only approximations were known. In addition, we present experimental results for financial networks and random networks. 相似文献
323.
324.
Johannes H. Hattingh Elizabeth Jonck Ernst J. Joubert 《Journal of Combinatorial Optimization》2010,20(3):205-223
Let G=(V,E) be a graph. A set of vertices S?V is a total restrained dominating set if every vertex is adjacent to a vertex in S and every vertex of $V-\nobreak S$ is adjacent to a vertex in V?S. The total restrained domination number of G, denoted by γ tr (G), is the smallest cardinality of a total restrained dominating set of G. A support vertex of a graph is a vertex of degree at least two which is adjacent to a leaf. We show that $\gamma_{\mathit{tr}}(T)\leq\lfloor\frac{n+2s+\ell-1}{2}\rfloor$ where T is a tree of order n≥3, and s and ? are, respectively, the number of support vertices and leaves of T. We also constructively characterize the trees attaining the aforementioned bound. 相似文献
325.
Ronaldo Parente Byeongyong Paul Choi Arjen H.L. Slangen Sonia Ketkar 《Journal of International Management》2010,16(3):275-287
Service firms play an increasingly important role in the global economy. However, the internationalization strategies of such firms, and especially their distribution system choices, have been underexplored in the international management literature. One specific service industry that has internationalized rapidly in recent years is the insurance industry. This paper examines the determinants and performance implications of the choice by international insurance firms between two rival distribution systems: direct writing and independent sales agents. Drawing on the transaction cost theory-based literature on resource commitment, control, and risk, we develop hypotheses on the determinants of the choice between these two distribution systems and on the performance implications of this choice for insurance firms. Analyzing a sample of 168 distribution entries into the United States by insurance firms from six foreign countries over the 1992–2000 period, we find that cultural distance has a U-shaped effect on the probability of direct writing, and that an insurer's intangible assets have a positive effect on this probability. We also find that the direct writing system performs better in terms of profitability, but that the independent agency system performs better in terms of market share growth. 相似文献
326.
Store brands are of increasing importance in retail supply chains, often causing channel conflict, as the retailer's product directly competes with the manufacturer's national brand. Extant research on the resulting channel interactions either assumes the national brand manufacturer can credibly commit to maintaining a wholesale price or that he lacks such ability. However, these two scenarios imply very different supply chain interactions, as only a national brand manufacturer with commitment ability can strategically adjust a national brand wholesale price to prevent a store brand introduction by the retailer. We specifically analyze the impact of this assumption on the manufacturer, the retailer, and the customers. We determine when long‐term contracts that provide the manufacturer with such commitment ability can improve supply chain profitability. 相似文献
327.
Resource flexibility is an important tool for firms to better match capacity with demand so as to increase revenues and improve service levels. However, in service contexts that require dynamically deciding whether to accept incoming jobs and what resource to assign to each accepted job, harnessing the benefits of flexibility requires using effective methods for making these operational decisions. Motivated by the resource deployment decisions facing a professional service firm in the workplace training industry, we address the dynamic job acceptance and resource assignment problem for systems with general resource flexibility structure, i.e., with multiple resource types that can each perform different overlapping subsets of job types. We first show that, for systems containing specialized resources for individual job types and a versatile resource type that can perform all job types, the exact policy uses a threshold rule. With more general flexibility structures, since the associated stochastic dynamic program is intractable, we develop and test three optimization‐based approximate policies. Our extensive computational tests show that one of the methods, which we call the Bottleneck Capacity Reservation policy, is remarkably effective in generating near‐optimal solutions over a wide range of problem scenarios. We also consider a model variant that requires dynamic job acceptance decisions but permits deferring resource assignment decisions until the end of the horizon. For this model, we discuss an adaptation of our approximate policy, establish the effectiveness of this policy, and assess the value of postponing assignment decisions. 相似文献
328.
Ruud H. Teunter M. Zied Babai Aris A. Syntetos 《Production and Operations Management》2010,19(3):343-352
ABC inventory classifications are widely used in practice, with demand value and demand volume as the most common ranking criteria. The standard approach in ABC applications is to set the same service level for all stock keeping units (SKUs) in a class. In this paper, we show (for three large real life datasets) that the application of both demand value and demand volume as ABC ranking criteria, with fixed service levels per class, leads to solutions that are far from cost optimal. An alternative criterion proposed by Zhang et al. performs much better, but is still considerably outperformed by a new criterion proposed in this paper. The new criterion is also more general in that it can take criticality of SKUs into account. Managerial insights are obtained into what class should have the highest/lowest service level, a topic that has been disputed in the literature. 相似文献
329.
The Freshwater Invertebrate Invasiveness Scoring Kit (FI‐ISK) is proposed as a screening tool for identifying potentially invasive freshwater invertebrates. FI‐ISK was adapted from the Fish Invasiveness Scoring Kit (FISK) of Copp, Garthwaite, and Gozlan, which is an adapted form of the Weed Risk Assessment (WRA) of Pheloung, Williams, and Halloy. Initial assessments using FI‐ISK, which include confidence (certainty/uncertainty) rankings by the assessor to each response, were calibrated to determine the most appropriate score thresholds for classifying nonnative species into low‐, medium‐, and high‐risk categories, using both the original medium‐to‐high risk threshold scores for the WRA (i.e., ≥6) and for FISK (i.e., ≥19). Patterns of the assessor's confidence, when making the responses during the FI‐ISK assessments, were also examined. Using receiver operating characteristic (ROC) curves, FI‐ISK was shown to distinguish accurately (and with statistical confidence) between potentially invasive and noninvasive species of nonnative crayfish (Decapoda: Astacidae, Cambaridae, Parastacidae), with the statistically appropriate threshold score for high‐risk species scores being ≥16. FI‐ISK represents a useful and viable tool to aid decision‐ and policymakers in assessing and classifying freshwater invertebrates according to their potential invasiveness. 相似文献
330.
Since its inception, the concept of absorptive capacity has been closely linked with notions of organizational learning. Yet the precise nature of the relationship between these two concepts has never been established. This relationship is examined in a variety of ways, and it is suggested that the literature on these two concepts shares a conceptual affinity which needs to be delineated. It is suggested that absorptive capacity (a dynamic capability) is a concrete example of organizational learning that concerns an organization's relationship with new external knowledge. Using the 4I Model for organizational learning ( Crossan, M.M., Lane, H.W. and White, R.E. (1999 ). An organizational learning framework: from intuition to institution. Academy of Management Review, 24, 522–537) and Zahra and George's conceptualization of absorptive capacity ( Zahra, S.A. and George, G. (2002 ). Absorptive capacity: a review, reconceptualization, and extension. Academy of Management Review, 27, 185–203), this paper proposes an integration of the two concepts. 相似文献