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    - MECHANICS (20 journals)
    - NUCLEAR PHYSICS (48 journals)
    - OPTICS (90 journals)
    - PHYSICS (572 journals)
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    - THERMODYNAMICS (31 journals)

PHYSICS (572 journals)            First | 1 2 3 4 5 6 | Last

Contemporary Concepts of Condensed Matter Science     Full-text available via subscription  
Contemporary Physics     Hybrid Journal   (Followers: 15)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Contributions to Plasma Physics     Hybrid Journal   (Followers: 2)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 1)
Cryogenics     Hybrid Journal   (Followers: 20)
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Diamond and Related Materials     Hybrid Journal   (Followers: 12)
Doklady Physics     Hybrid Journal   (Followers: 1)
Dynamical Properties of Solids     Full-text available via subscription  
ECS Journal of Solid State Science and Technology     Full-text available via subscription   (Followers: 2)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 5)
EJNMMI Physics     Open Access  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 25)
Energy Procedia     Open Access   (Followers: 4)
Engineering Failure Analysis     Hybrid Journal   (Followers: 43)
Engineering Fracture Mechanics     Hybrid Journal   (Followers: 21)
Environmental Fluid Mechanics     Hybrid Journal   (Followers: 3)
EPJ Nonlinear Biomedical Physics     Open Access  
EPJ Quantum Technology     Open Access  
EPJ Techniques and Instrumentation     Full-text available via subscription  
EPJ Web of Conferences     Open Access  
European Journal of Physics     Full-text available via subscription   (Followers: 5)
European Journal of Physics Education     Open Access   (Followers: 4)
European Physical Journal - Applied Physics     Full-text available via subscription   (Followers: 6)
European Physical Journal C     Hybrid Journal  
Europhysics News     Open Access  
Experimental Mechanics     Hybrid Journal   (Followers: 20)
Experimental Methods in the Physical Sciences     Full-text available via subscription  
Experimental Techniques     Hybrid Journal   (Followers: 48)
Exploration Geophysics     Hybrid Journal   (Followers: 5)
Few-Body Systems     Hybrid Journal  
Fire and Materials     Hybrid Journal   (Followers: 6)
Flexible Services and Manufacturing Journal     Hybrid Journal   (Followers: 1)
Fluctuation and Noise Letters     Hybrid Journal   (Followers: 1)
Fluid Dynamics     Hybrid Journal   (Followers: 6)
Fortschritte der Physik/Progress of Physics     Hybrid Journal  
Frontiers in Physics     Open Access   (Followers: 4)
Frontiers of Materials Science     Hybrid Journal   (Followers: 4)
Frontiers of Physics     Hybrid Journal   (Followers: 1)
Fusion Engineering and Design     Hybrid Journal   (Followers: 8)
Geochemistry, Geophysics, Geosystems     Full-text available via subscription   (Followers: 25)
Geografiska Annaler, Series A: Physical Geography     Hybrid Journal   (Followers: 3)
Geophysical Research Letters     Full-text available via subscription   (Followers: 56)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 20)
Glass Physics and Chemistry     Hybrid Journal   (Followers: 2)
Global Journal of Physics     Open Access   (Followers: 1)
Granular Matter     Hybrid Journal   (Followers: 2)
Graphs and Combinatorics     Hybrid Journal   (Followers: 7)
Gravitation and Cosmology     Hybrid Journal  
Handbook of Geophysical Exploration: Seismic Exploration     Full-text available via subscription  
Handbook of Metal Physics     Full-text available via subscription  
Handbook of Surface Science     Full-text available via subscription   (Followers: 3)
Handbook of Thermal Analysis and Calorimetry     Full-text available via subscription  
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Heat Transfer - Asian Research     Hybrid Journal   (Followers: 8)
High Energy Density Physics     Hybrid Journal   (Followers: 3)
High Pressure Research: An International Journal     Hybrid Journal   (Followers: 1)
IEEE Journal of Quantum Electronics     Hybrid Journal   (Followers: 17)
IEEE Signal Processing Magazine     Full-text available via subscription   (Followers: 47)
IET Optoelectronics     Hybrid Journal   (Followers: 3)
Il Colle di Galileo     Open Access  
Imaging Science Journal     Hybrid Journal   (Followers: 3)
Indian Journal of Biochemistry and Biophysics (IJBB)     Open Access   (Followers: 4)
Indian Journal of Physics     Hybrid Journal   (Followers: 4)
Indian Journal of Pure & Applied Physics (IJPAP)     Open Access   (Followers: 9)
Indian Journal of Radio & Space Physics (IJRSP)     Open Access   (Followers: 6)
Industrial Electronics, IEEE Transactions on     Hybrid Journal   (Followers: 17)
Industry Applications, IEEE Transactions on     Hybrid Journal   (Followers: 4)
Infinite Dimensional Analysis, Quantum Probability and Related Topics     Hybrid Journal  
InfraMatics     Open Access  
Infrared Physics & Technology     Hybrid Journal  
Intelligent Transportation Systems Magazine, IEEE     Full-text available via subscription   (Followers: 4)
Intermetallics     Hybrid Journal   (Followers: 25)
International Applied Mechanics     Hybrid Journal   (Followers: 3)
International Geophysics     Full-text available via subscription   (Followers: 4)
International Heat Treatment and Surface Engineering     Hybrid Journal   (Followers: 2)
International Journal for Computational Methods in Engineering Science and Mechanics     Hybrid Journal   (Followers: 10)
International Journal for Ion Mobility Spectrometry     Hybrid Journal   (Followers: 1)
International Journal for Simulation and Multidisciplinary Design Optimization     Full-text available via subscription   (Followers: 1)
International Journal of Abrasive Technology     Hybrid Journal   (Followers: 2)
International Journal of Aeroacoustics     Full-text available via subscription   (Followers: 25)
International Journal of Applied Electronics in Physics & Robotics     Open Access   (Followers: 1)
International Journal of Astronomy and Astrophysics     Open Access   (Followers: 2)
International Journal of Computational Materials Science and Surface Engineering     Hybrid Journal   (Followers: 8)
International Journal of Damage Mechanics     Hybrid Journal   (Followers: 5)
International Journal of Fatigue     Hybrid Journal   (Followers: 36)
International Journal of Fracture     Hybrid Journal   (Followers: 9)
International Journal of Geometric Methods in Modern Physics     Hybrid Journal   (Followers: 1)
International Journal of Geophysics     Open Access   (Followers: 6)
International Journal of Heat and Fluid Flow     Hybrid Journal   (Followers: 24)
International Journal of Low Radiation     Hybrid Journal  
International Journal of Low-Carbon Technologies     Open Access   (Followers: 1)
International Journal of Mass Spectrometry     Hybrid Journal   (Followers: 15)
International Journal of Material Forming     Hybrid Journal   (Followers: 2)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 3)
International Journal of Mechanical Sciences     Hybrid Journal   (Followers: 7)
International Journal of Mechanics and Materials in Design     Hybrid Journal   (Followers: 5)
International Journal of Medical Physics, Clinical Engineering and Radiation Oncology     Open Access   (Followers: 6)
International Journal of Micro-Nano Scale Transport     Full-text available via subscription   (Followers: 1)

  First | 1 2 3 4 5 6 | Last

Journal Cover Flexible Services and Manufacturing Journal
  [SJR: 1.277]   [H-I: 28]   [1 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1936-6582 - ISSN (Online) 1936-6590
   Published by Springer-Verlag Homepage  [2280 journals]
  • Inter-terminal transportation: an annotated bibliography and research
    • Abstract: Abstract The seemingly unlimited growth of containerized transport is nowadays associated with an increasing number of seaport container terminals and facilities as well as demand for port-centric value-added and just-in-time logistics services. Intense global and local competition as well as geographical limitations urgently require efficient means to handle inter-terminal transportation. Many factors influence the productivity and efficiency of inter-terminal transportation as well as its economic and environmental implications. In the last two decades, these aspects have led to a growing interest in research, in particular concerning decision analytics and innovative information technology aiming to better understand, improve, and operate inter-terminal transportation. In this paper, we present a chronological overview of related works as an annotated bibliography in order to reflect the current state of research. Furthermore, we identify future research issues and propose a respective research agenda.
      PubDate: 2016-01-29
  • A note on the selection of priority rules in software packages for project
    • Abstract: Abstract Various software packages for project management include a procedure for resource-constrained scheduling. In several packages, the user can influence this procedure by selecting a priority rule. However, the resource-allocation methods that are implemented in the procedures are proprietary information; therefore, the question of how the priority-rule selection impacts the performance of the procedures arises. We experimentally evaluate the resource-allocation methods of eight recent software packages using the 600 instances of the PSPLIB J120 test set. The results of our analysis indicate that applying the default rule tends to outperform a randomly selected rule, whereas applying two randomly selected rules tends to outperform the default rule. Applying a small set of more than two rules further improves the project durations considerably. However, a large number of rules must be applied to obtain the best possible project durations.
      PubDate: 2016-01-16
  • Extraction and visualization of industrial service portfolios by text
           mining of 10-K annual reports
    • Abstract: Abstract As more and more manufacturing companies accumulate profits from service provision, the ability to monitor the adoption of the industrial services of other companies grows more important. The purpose of this paper is to propose a data-driven methodology for extraction of the industrial service portfolio from a company’s annual report. In this approach, form 10-K, a special format of annual report regulated by the Security Exchange Commission in United States is utilized as the data source. Because this document type contains rich information on a company’s operating segments, industrial service information is easily retrieved. Given the sheer volume of such documents, however, manual inspection is impractical. In order to resolve this issue, a text-mining algorithm is applied to automatically examine word-usage patterns and to identify the service portfolio. Then, the service portfolio’s relative position in the market is visualized on a positioning map. Due to the multi-dimensionality of the data, self-organizing map (SOM) is used as an alternative visualization scheme. SOM enables easy identification of the major service clusters as well as niche areas in the market; these, in turn, provide valuable information pertinent to service development planning. Also, and not least, policy makers can utilize our methodology to detect the servitization trends of various industries.
      PubDate: 2016-01-13
  • Shift scheduling with break windows, ideal break periods, and ideal
           waiting times
    • Abstract: Abstract This paper is concerned with the shift scheduling problem involving multiple breaks with different durations and multiple break windows for each shift. We have incorporated ideal break periods and ideal waiting time into the original problem previously presented in the literature. As an extension of the implicit integer programming model with a single goal of minimizing the labor cost, we have proposed an implicit preemptive goal programming model involving three goals, which are given in order of their priority levels as follows: (1) minimize the labor cost; (2) maximize the number of employees that receive their breaks at ideal break periods; (3) make the waiting times of the employees between their consecutive breaks equal to the ideal waiting time, i.e. minimize the deviations from ideal waiting time. The ideal waiting time is incorporated into the model implicitly by matching the periods within the break windows. We aim at improving the break schedules through a more sensitive timing of the breaks, without causing an increase in the labor cost. The computational results obtained on randomly generated test problems indicate that the extended model may yield considerable improvement in the break placement.
      PubDate: 2015-12-28
  • Comparison of three flow line layouts with unreliable machines and profit
    • Abstract: Abstract Manufacturing system design is a complex challenge when a new factory is being built. Although some factories produce the same product, the layouts of the factories may be different. Manufacturing systems for automotive engines can be modelled with several types of queueing networks with finite buffers and unreliable machines. In this paper, three types of layout structures which are commonly used in automotive engine shops are compared with respect to maximizing profit that is determined by throughput and the investment cost of buffers. We assume that the service times are constant but inhomogeneous, and the time to failure and the time to repair are exponentially distributed. To solve this problem we used approximation methods which are based on aggregation and overlapping decomposition for computing performance measures, and a gradient search method for finding an optimal buffer allocation.
      PubDate: 2015-12-17
  • Health Care Systems Engineering
    • PubDate: 2015-12-12
  • Rolling horizon planning for a dynamic collaborative routing problem with
           full-truckload pickup and delivery requests
    • Abstract: Abstract In order to improve their operational efficiency, small and mid-sized freight forwarders can establish horizontal coalitions in order to exchange customer requests. Decentralized operational transportation planning processes enabling request exchange among forwarders in spite of information asymmetry and distributed decision-making competences is referred to as collaborative transportation planning (CTP). CTP can help forwarders take advantage of economies of scale and reduce their costs of fulfilling customer requests compared to the case of isolated planning without request exchange. In order to exploit the potential of cost-savings embedded in CTP, appropriate request exchange mechanisms have to be developed. In this paper, the dynamic CTP problem of a coalition of freight forwarders serving full-truckload transport requests is studied. Two rolling horizon planning approaches are proposed to solve the dynamic routing problems. It is analyzed how the planning results, in particular the cost reduction realized by CTP, are influenced by different planning settings. Computational experiments show that the planning results of CTP are considerably superior to those obtained by isolated planning, and the realized cost-savings in percentage remain relatively constant, independently of the test settings.
      PubDate: 2015-12-01
  • Mixed bundle retailing under a stochastic market
    • Abstract: Abstract Bundling is a pervasive marketing strategy in real business. In this paper, we study the strategy of mixed bundling under a stochastic market for two products for a retailer who has monopolistic power in the market, and the bundle consists of one unit of each individual product. The retailer needs to make joint pricing and inventory decisions with the aim of maximizing expected profit. Firstly, the relationship between the prices and market shares of the three bundle variations in the mixed bundling strategy is modeled after the reservation price model, which is commonly adopted in the bundling literature. Based on the market shares, a two-stage stochastic model is proposed to determine inventory decisions, including the ordering decision before the selling season starts and the allocation decisions after demands are realized. Global concavity in the order quantities is demonstrated. For experimental purposes, an algorithm incorporating both pricing and inventory decisions is presented. We measure the importance of incorporating inventory matters into bundling decisions under the stochastic market by calculating expected loss of profit, which can exceed 5 % under some parameter settings. In the numerical experiments, we identify two attributes of mixed bundling performance, which are bundling pricing effect and inventory pooling effect.
      PubDate: 2015-12-01
  • Planning of a make-to-order production process in the printing industry
    • Abstract: Abstract Offset printing is a common method to produce large amounts of printed matter. We consider a real-world offset printing process that is used to imprint customer-specific designs on napkin pouches. The production equipment used gives rise to various technological constraints. The planning problem consists of allocating designs to printing-plate slots such that the given customer demand for each design is fulfilled, all technological and organizational constraints are met and the total overproduction and setup costs are minimized. We formulate this planning problem as a mixed-binary linear program, and we develop a multi-pass matching-based savings heuristic. We report computational results for a set of problem instances devised from real-world data.
      PubDate: 2015-12-01
  • Planning of waste electrical and electronic equipment (WEEE) recycling
           facilities: MILP modelling and case study investigation
    • Abstract: Abstract Waste electrical and electronic equipment (WEEE) consist of many different substances some of which contain hazardous components and valuable materials. The recovery of WEEE plays a key role on environmental sustainability because it minimizes the negative effects of hazardous materials and helps the efficient use of world’s limited resources. Recovery strategies enable companies to collect reusable components and to recycle the material content of WEEE by using operations like sorting, disassembly and bulk recycling. Usually companies associated with municipals collect WEEE from end-users and/or collection points. Then they sell these items to WEEE recycling facilities through bidding. For recycling facilities, it is important to generate the best operational level decisions to receive and handle WEEE. This study contributes to the fulfillment of this need by presenting a mixed integer linear programming model to determine the maximum bid price offer while determining the best operation planning strategies. In order to demonstrate the potential of the proposed model, a real life case study along with several scenarios is studied. The findings of the case study indicate that the model has the potential to enable the decision maker to come with stronger decisions related to both bidding process and operational strategies of the facility.
      PubDate: 2015-12-01
  • A quay crane system that self-recovers from random shocks
    • Abstract: Abstract The main challenge for a container terminal is to maximize its throughput using limited resources subject to various operational constraints under uncertainty. Traditional methods try to achieve this through an optimized plan by solving a quay crane scheduling problem; but the plan may become obsolete or infeasible after shocks (changes in the system due to uncertainty). To respond to shocks these methods require frequent re-planning, which increases the operations cost. We propose a new method to counter this. Instead of creating plans, we develop an operating protocol to respond to shocks without re-planning. Under this protocol, each quay crane along a berth follows simple rules to serve vessels that arrive continuously in time. If the system is configured properly, it always spontaneously recovers to its efficient form after a random shock. The average throughput of the system operating on its efficient form is very near its full capacity if the crane travel time per bay is relatively short. This self-recovery is robust even under a sequence of shocks as the system persistently restores its throughput after each shock. Most importantly, this is accomplished without complex computation.
      PubDate: 2015-12-01
  • An estimation of distribution algorithm and new computational results for
           the stochastic resource-constrained project scheduling problem
    • Abstract: Abstract In this paper we propose an estimation of distribution algorithm (EDA) to solve the stochastic resource-constrained project scheduling problem. The algorithm employs a novel probability model as well as a permutation-based local search. In a comprehensive computational study, we scrutinize the performance of EDA on a set of widely used benchmark instances. Thereby, we analyze the impact of different problem parameters as well as the variance of activity durations. By benchmarking EDA with state-of-the-art algorithms, we can show that its performance compares very favorably to the latter, with a clear dominance in instances with medium to high variance of activity duration.
      PubDate: 2015-12-01
  • A new approach to the Container Positioning Problem
    • Abstract: Abstract In this paper the Container Positioning Problem is revisited. This problem arises at busy container terminals and requires one to minimize the use of block cranes in handling the containers that must wait at the terminal until their next means of transportation. We propose a new Mixed Integer Programming model that not only improves on earlier attempts at this problem, but also better reflects reality. In particular, the proposed model adopts a preference to reshuffle containers in line with a just-in-time concept, as it is assumed that data is more accurate the closer to a container’s scheduled departure the time is. Other important improvements include a reduction in the model size, and the ability of the model to consider containers initially at the terminal. In addition, we describe several classes of valid inequalities for this new formulation and present a rolling horizon based heuristic for solving larger instances of the problem. We show that this new formulation drastically outperforms previous attempts at the problem through a direct comparison on instances available in the literature. Furthermore, we also show that the rolling horizon based heuristic can further reduce the solution time on the larger of these instances as well as find acceptable solutions to much bigger, artificially generated, instances.
      PubDate: 2015-10-24
  • RFID analytics for hospital ward management
    • Abstract: Abstract In this paper, we present an RFID-enabled platform for hospital ward management. Active RFID tags are attached to individuals and assets in the wards. Active RFID readers communicate with the tags continuously and automatically to keep track of the real-time information about the locations of the tagged objects. The data regarding the locations and other transmitted information are stored in the ward management system. This platform enables capabilities of real-time monitoring and tracking of individuals and assets, reporting of ward statistics, and providing intelligence and analytics for hospital ward management. All of these capabilities benefit hospital ward management by enhanced patient safety, increased operational efficiency and throughput, and mitigation of risk of infectious disease widespread. A prototype developed based on our proposed architecture of the platform was tested in a pilot study, which was conducted in two medical wards of the intensive care unit of one of the largest public general hospitals in Hong Kong. This pilot study demonstrates the feasibility of the implementation of this RFID-enabled platform for practical use in hospital wards. Furthermore, the data collected from the pilot study are used to provide data analytics for hospital ward management.
      PubDate: 2015-10-23
  • Daily nurse requirements planning based on simulation of patient flows
    • Abstract: Abstract Nurses account for approximately 50 % of total hospital budgets and their allocation to medical units and shifts can significantly affect the quality of care provided to patients. The adoption of flexible shift schedules and the assessment of actual nursing time can enable sensible resource planning, balancing the quality of care with efficiency in resource use. Starting from the concept that nurse requirements are triggered by patient needs, which are stochastic in nature both for clinical activities and their duration, this paper proposes an innovative Nurse Requirement Planning model grounded on the concept of the clinical pathway (the “standard” sequence of diagnostic, therapeutic and care activities a patient with certain pathology should undertake over time) with its inner routing probability and patient dependence on nurses, which can be correlated to the time needed to perform nursing tasks. In merging and modelling these two aspects, the method summarizes the best features of acuity-quality and timed-task/activity techniques, well known although not usually applied for reasons of demands on clinicians’ time. Instead, in this paper, for each shift of the day, hospital management is enabled to choose the optimal number of nurses to meet actual requirements according to a desired service level and personnel saturation by means of a tool that simulates the patient flow in a medical unit based on automatic data retrieval from hospital databases. The validation and verification of the proposal were undertaken in a stroke unit.
      PubDate: 2015-10-23
  • Tree search procedures for the blocks relocation problem with batch moves
    • Abstract: Abstract This research investigates a blocks relocation problem with batch moves (BRP-BM) mainly arising from the operations at slab yards in iron and steel plants. Several recent types of bridge cranes used in hot rolling slab yards can handle up to three slabs in one move, resulting in a typical scenario of the BRP-BM. A lower bound of the number of moves for the BRP-BM is presented. A greedy algorithm and three tree search algorithms, including one based on compound moves, are designed to solve the BRP-BM. The lower bound and the algorithms are validated and extensively evaluated based on both existing instances and randomly generated instances. The results indicate that the tree search algorithm based on compound moves outperforms the other algorithms especially for large-sized instances. Roughly speaking, the relative number of moves decreases from 1 to 0.80 and to 0.75 if the batch size increases from 1 to 2 and then to 3.
      PubDate: 2015-10-19
  • Daily scheduling of home health care services using time-dependent public
    • Abstract: Abstract This paper presents a real-world optimization problem in home health care that is solved on a daily basis. It can be described as follows: care staff members with different qualification levels have to visit certain clients at least once per day. Assignment constraints and hard time windows at the clients have to be observed. The staff members have a maximum working time and their workday can be separated into two shifts. A mandatory break that can also be partitioned needs to be scheduled if the consecutive working time exceeds a certain threshold. The objective is to minimize the total travel- and waiting times of the care staff. Additionally, factors influencing the satisfaction of the clients or the care staff are considered. Most of the care staff members from the Austrian Red Cross (ARC) in Vienna use a combination of public transport modes (bus, tram, train, and metro) and walking. We present a novel model formulation for this problem, followed by an efficient exact solution approach to compute the time-dependent travel times out of the timetables from public transport service providers on a minute-basis. These travel time matrices are then used as input for three Tabu Search based solution methods for the scheduling problem. Extensive numerical studies with real-world data from the ARC show that the current planning can be improved significantly when these methods are applied.
      PubDate: 2015-10-13
  • A novel multistage deep belief network based extreme learning machine
           ensemble learning paradigm for credit risk assessment
    • Abstract: Abstract To achieve high assessment accuracy for credit risk, a novel multistage deep belief network (DBN) based extreme learning machine (ELM) ensemble learning methodology is proposed. In the proposed methodology, three main stages, i.e., training subsets generation, individual classifiers training and final ensemble output, are involved. In the first stage, bagging sampling algorithm is applied to generate different training subsets for guaranteeing enough training data. Second, the ELM, an effective AI forecasting tool with the unique merits of time-saving and high accuracy, is utilized as the individual classifier, and diverse ensemble members can be accordingly formulated with different subsets and different initial conditions. In the final stage, the individual results are fused into final classification output via the DBN model with sufficient hidden layers, which can effectively capture the valuable information hidden in ensemble members. For illustration and verification, the experimental study on one publicly available credit risk dataset is conducted, and the results show the superiority of the proposed multistage DBN-based ELM ensemble learning paradigm in terms of high classification accuracy.
      PubDate: 2015-09-29
  • A cooperative quay crane-based stochastic model to estimate vessel
           handling time
    • Abstract: Abstract Having a good estimate of a vessel’s handling time is essential for planning and scheduling container terminal resources, such as berth positions, quay cranes (QCs) and transport vehicles. However, estimating the expected vessel handling time is not straightforward , because it depends on vessel characteristics, resource allocation decisions, and uncertainties in terminal processes. To estimate the expected vessel handling time, we propose a two-level stochastic model. The higher level model consists of a continuous-time Markov chain (CTMC) that captures the effect of QC assignment and scheduling on vessel handling time . The lower level model is a multi-class closed queuing network that models the dynamic interactions among the terminal resources and provides an estimate of the transition rate input parameters to the higher level CTMC model. We estimate the expected vessel handling times for several container load and unload profiles and discuss the effect of terminal layout parameters and crane service time variabilities on vessel handling times. From numerical experiments, we find that by having QCs cooperate, the vessel handling times are reduced by up to 15 %. The vessel handling time is strongly dependent on the variation in the QC service time and on the vehicle travel path topology.
      PubDate: 2015-09-21
  • Equilibrium models in multimodal container transport systems
    • Abstract: Abstract Optimizing the performance of multimodal freight transport networks involves adequately balancing the interplay between costs, volumes, times of departure and arrival, and times of travel. In order to study this interplay, we propose an assignment model that is able to efficiently determine flows and costs in a multimodal network. The model is based on a so-called user equilibrium principle, which is at the basis of Dynamic Traffic Assignment problems. This principle takes into account transport demands to be shipped using vehicles that transport single freight units (such as trucks) or multiple freight units (such as trains and barges, where demand should be bundled to reach efficient operations). Given a particular demand, the proposed model provides an assignment of the demand over the available modes of transport. The outcome of the model, i.e., the equilibrium point, minimizes users’ generalized costs, expressed as a function of mode, travel time and related congestion, and waiting time for bundling sufficient demand in order to fill a vehicle. The model deals with these issues across a doubly-dynamic time scale and in an integrated manner. One dynamic involves a learning dynamic converging towards an equilibrium (day-to-day) situation, reflecting the reaction of the players towards the action of the others. Another dynamic considers the possible departure time that results in minimum expected costs, also due to the fact that players mutually influence each other on the choice of departure times, due to congestion effects and costs for early/late arrival of freight units. This is a choice within a given time horizon such as a day or a week. We present a study on the influence and sensitivity of different model parameters, in order to analyse the implications on strategic decisions, fostering a target modal share for freight transportation. We also study under which conditions the different modes can be substitutes for each other.
      PubDate: 2015-09-04
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