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Capacity Constraints (capacity + constraint)
Selected AbstractsAn equity-based passenger flow control model with application to Hong Kong-Shenzhen border-crossingJOURNAL OF ADVANCED TRANSPORTATION, Issue 2 2002Hai Yang Cross-border passengers from Hong Kong to Shenzhen by the east Kowloon-Canton Railway (KCR) through the Lo Wu customs exceed nearly 200 thousand on a special day such as a day during the Chinese Spring Festival. Such heavy passenger demand often exceeds the processing and holding capacity of the Lo Wu customs for many hours a day. Thus, passengers must be metered off at all entrance stations along the KCR line through ticket rationing to restrain the number of passengers waiting at Lo Wu within its safe holding capacity. This paper proposes an optimal control strategy and model to deal with this passenger crowding and control problem. Because the maximum passenger checkout rate at Lo Wu is fixed, total passenger waiting time is not affected by the control strategy for given time-dependent arriving rates at each station. An equity-based control strategy is thus proposed to equalize the waiting times of passengers arriving at all stations at the same time. This equity is achieved through optimal allocation of the total quota of tickets to all entrance stations for each train service. The total ticket quota for each train service is determined such that the capacity constraint of the passenger queue at Lo Wu is satisfied. The control problem is formulated as a successive linear programming problem and demonstrated for the KCR system with partially simulated data. [source] Aid and Reform in Failing StatesASIAN-PACIFIC ECONOMIC LITERATURE, Issue 1 2008Lisa Chauvet This paper reviews the policy implications of research on reform in failing states (Chauvet and Collier 2006, 2007a, 2007b, 2008; Chauvet et al. 2006; Chauvet et al. 2007a, 2007b). After providing a precise definition of state failure and reform in such states, we present the internal constraints impeding reform in failing states. Élite preferences and insufficient social knowledge seem to be the major constraints on reform. We find that financial aid tends to allow the ruling élite to postpone reform. Technical assistance, however, has some effectiveness in relaxing the capacity constraint to implement reform, notably right at the beginning of reform. [source] The Financial Impact of Ambulance Diversions and Patient ElopementsACADEMIC EMERGENCY MEDICINE, Issue 1 2007Thomas Falvo DO Abstract Objectives Admission process delays and other throughput inefficiencies are a leading cause of emergency department (ED) overcrowding, ambulance diversion, and patient elopements. Hospital capacity constraints reduce the number of treatment beds available to provide revenue-generating patient services. The objective of this study was to develop a practical method for quantifying the revenues that are potentially lost as a result of patient elopements and ambulance diversion. Methods Historical data from 62,588 patient visits to the ED of a 450-bed nonprofit community teaching hospital in central Pennsylvania between July 2004 and June 2005 were used to estimate the value of potential patient visits foregone as a result of ambulance diversion and patients leaving the ED without treatment. Results The study hospital may have lost $3,881,506 in net revenue as a result of ambulance diversions and patient elopements from the ED during a 12-month period. Conclusions Significant revenue may be foregone as a result of throughput delays that prevent the ED from utilizing its existing bed capacity for additional patient visits. [source] A Framework for Facilitating Sourcing and Allocation Decisions for Make-to-Order ItemsDECISION SCIENCES, Issue 4 2004Nagesh N. Murthy ABSTRACT This paper provides a fundamental building block to facilitate sourcing and allocation decisions for make-to-order items. We specifically address the buyer's vendor selection problem for make-to-order items where the goal is to minimize sourcing and purchasing costs in the presence of fixed costs, shared capacity constraints, and volume-based discounts for bundles of items. The potential suppliers for make-to-order items provide quotes in the form of single sealed bids or participate in a dynamic auction involving open bids. A solution to our problem can be used to determine winning bids amongst the single sealed bids or winners at each stage of a dynamic auction. Due to the computational complexity of this problem, we develop a heuristic procedure based on Lagrangian relaxation technique to solve the problem. The computational results show that the procedure is effective under a variety of scenarios. The average gap across 2,250 problem instances is 4.65%. [source] Elites in Local Development in the PhilippinesDEVELOPMENT AND CHANGE, Issue 1 2010Andreas Lange ABSTRACT For many Philippine provinces, decentralization and more autonomous local development planning did not lead to the desired outcomes. This article examines the experiences of the two provinces of Cebu and Leyte. While Cebu became a centre of trade and industry, Leyte is still struggling with its local economy oriented to natural resources. A main reason for the divergent development paths of the two islands can be found in the emergence of different elite structures, which resulted in different path-dependent patterns of economic specialization. Despite this different historical experience, both provinces today suffer from similar institutional infirmities in their planning system for promoting local development. Local planning capacity constraints, such as regional and local co-ordination and co-operation patterns, local finances, human capital and knowledge are analysed. The Cebuano elites used the room for manoeuvre provided by decentralization reforms more successfully than elites in Leyte. This created pockets of efficiency in Cebu leading to more development-friendly investment policies. In order to increase local and regional planning capacity, short-term interventions and policy reforms at the local, regional and national level are discussed. [source] TERRORISM AND THE RETURNS TO OILECONOMICS & POLITICS, Issue 3 2009BROCK BLOMBERG The effect of terrorism on global oil prices has been largely explained through demand-side effects. We estimate an empirical model to re-examine the effect of terrorism on the price of global oil stocks across oil market regimes that reflect different supply constraints. We believe that terrorism will have larger impacts when global capacity is tight (i.e. when global demand is close to global supply). This means that any shock to capacity (say by conflict) should have the largest impact on profits before the first OPEC shock in the early 1970s. Since then, conflict shocks would not allow firms to exploit production in the same way, thus reducing the available profits that could be garnered by such production manipulation. If capacity constraints are binding when a conflict occurs, then we predict that a positive stock price reaction can be expected for oil firms from such a shock. We exploit a new panel dataset to investigate the relationship between oil profitability and conflict, using conflict data from the top 20 oil producing and exporting countries in the world. We show that in the later part of our sample, 1974,2005, as cartel behavior of OPEC member countries has diminished and as conflict has become more regular and thus the information surrounding it noisier, oil stock prices do not increase in response to conflict. However, in earlier capacity constrained eras, we find that oil stocks can in fact increase in response to conflict. In some cases, the impact of conflict may cause the return of oil stocks to increase by as much as 10 percentage points. [source] Solution of the Dial-a-Ride Problem with multi-dimensional capacity constraintsINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 3 2006K. I. Wong Abstract The Dial-a-Ride Problem (DARP) consists of planning routes and schedules for picking up and delivering users within user-specified time windows. Vehicles of a given fleet with limited capacity depart from and end at a common depot. The travel time of passengers cannot exceed a given multiple of the minimum ride time. Other constraints include vehicle capacity and vehicle route duration. In practice, scheduling is made more complicated by special user requirements and an inhomogeneous vehicle fleet. The transportation of elderly and handicapped people is an important example, as space for wheelchairs is limited and a lift is required. In this study, we present a modified insertion heuristic to solve the DARP with multi-dimensional capacity constraints, and the performance of the proposed algorithm is tested in simulation. We show that the proposed methodology is effective when compared with the classic algorithms. [source] General stochastic user equilibrium traffic assignment problem with link capacity constraintsJOURNAL OF ADVANCED TRANSPORTATION, Issue 4 2008Qiang Meng Abstract This paper addresses a general stochastic user equilibrium (SUE) traffic assignment problem with link capacity constraints. It first proposes a novel linearly constrained minimization model in terms of path flows and then shows that any of its local minimums satisfies the generalized SUE conditions. As the objective function of the proposed model involves path-specific delay functions without explicit mathematical expressions, its Lagrangian dual formulation is analyzed. On the basis of the Lagrangian dual model, a convergent Lagrangian dual method with a predetermined step size sequence is developed. This solution method merely invokes a subroutine at each iteration to perform a conventional SUE traffic assignment excluding link capacity constraints. Finally, two numerical examples are used to illustrate the proposed model and solution method. [source] Aid allocation to fragile states: Absorptive capacity constraintsJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 5 2009Simon Feeny Abstract The international donor community has grave concerns about the effectiveness of aid to countries it classifies as ,fragile states'. The impact of aid on growth and poverty reduction and the ability to efficiently absorb additional inflows is thought to be significantly lower in these countries compared to other recipients. This paper examines this issue and suggests that a while a number of fragile states can efficiently absorb more aid than they have received, a number receive far more aid than they can efficiently absorb from a perspective based purely on per capita income growth. Policy recommendations are provided. Copyright © 2008 John Wiley & Sons, Ltd. [source] Employment Adjustment at the Firm Level.LABOUR, Issue 1 2002A Theoretical Model, an Empirical Investigation for West German Manufacturing Firms In this paper, employment adjustment at the firm level is estimated with a large panel of business survey data from West German manufacturing. The specification is based on a framework of monopolistic competition in the product market. Special emphasis is devoted to the analysis of the impact of demand uncertainty, capacity constraints, technological change and competition. The empirical results reveal that demand uncertainty and capacity constraints significantly affect employment adjustment. Innovative firms are more successful; they increase employment and exhibit a higher utilization of capacities. Employment adjustment also depends on competition. In monopolistic markets, the volatility of employment is higher. [source] Vertical merger: monopolization for downstream quasi-rentsMANAGERIAL AND DECISION ECONOMICS, Issue 3 2009Richard S. Higgins This paper provides a welfare analysis of vertical merger between an input monopolist and downstream firms that compete perfectly in a homogeneous product market. The distinguishing feature of the present model is that the downstream firms face capacity constraints. As a result of downstream quasi-rents, vertical merger,the extent of merger is gauged by the capacity share of the acquired downstream firm,may either raise or lower final output. An analytical criterion for distinguishing pro- and anti-competitive mergers is derived, which relies entirely on pre-merger market quantities and the capacity share of the downstream target. A common result is that vertical merger is output-increasing even when unaffiliated downstream rivals are completely foreclosed. Copyright © 2008 John Wiley & Sons, Ltd. [source] The value of information sharing in a two-stage supply chain with production capacity constraintsNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 8 2003David Simchi-Levi Abstract We consider a simple two-stage supply chain with a single retailer facing i.i.d. demand and a single manufacturer with finite production capacity. We analyze the value of information sharing between the retailer and the manufacturer over a finite time horizon. In our model, the manufacturer receives demand information from the retailer even during time periods in which the retailer does not order. To analyze the impact of information sharing, we consider the following three strategies: (1) the retailer does not share demand information with the manufacturer; (2) the retailer does share demand information with the manufacturer and the manufacturer uses the optimal policy to schedule production; (3) the retailer shares demand information with the manufacturer and the manufacturer uses a greedy policy to schedule production. These strategies allow us to study the impact of information sharing on the manufacturer as a function of the production capacity, and the frequency and timing in which demand information is shared. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003 [source] The multiroute maximum flow problem revisitedNETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2006Donglei Du Abstract We are given a directed network G = (V,A,u) with vertex set V, arc set A, a source vertex s , V, a destination vertex t , V, a finite capacity vector u = {uij}(i,j),A, and a positive integer m , Z+. The multiroute maximum flow problem (m -MFP) generalizes the ordinary maximum flow problem by seeking a maximum flow from s to t subject to not only the regular flow conservation constraints at the vertices (except s and t) and the flow capacity constraints at the arcs, but also the extra constraints that any flow must be routed along m arc-disjoint s - t paths. In this article, we devise two new combinatorial algorithms for m -MFP. One is based on Newton's method and another is based on an augmenting-path technique. We also show how the Newton-based algorithm unifies two existing algorithms, and how the augmenting-path algorithm is strongly polynomial for case m = 2. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 47(2), 81,92 2006 [source] Solving the Hub location problem in telecommunication network design: A local search approachNETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2004G. Carello Abstract This article deals with a Hub Location Problem arising in Telecommunication Network Design. The considered network presents two different kinds of nodes: access nodes, that represent source and destination of traffic demands but cannot be directly connected, and transit nodes, that have no own traffic demand but collect traffic from access nodes and route it through the network. Transit nodes are supposed to be fully connected. Given a set of access nodes and a set of potential locations for the transit nodes, the problem is to decide number and positions of the transit nodes to guarantee that all access nodes are allocated to a transit node, satisfying capacity constraints. The goal is to minimize the total cost of the network, which is the sum of connection costs and nodes fixed costs. The problem is a Hub Location Problem, which is known to be NP-hard. A local search approach is proposed, and different metaheuristic algorithms, such as tabu search, iterated local search and random multistart, have been developed, based on such local search. [A preliminary procedure has been developed in a research project joint with Telecom Italia (Turin Research & Innovation Laboratories) and a patent application has been filed to cover this issue.] © 2004 Wiley Periodicals, Inc. NETWOEKS, Vol. 44(2), 94,105 2004 [source] | ||||||||||||||||