The non-Gaussian three-chain, eight-chain and full network models for rubber elasticity are cast in rate from. For computational converlency, incompressibility is incorporated through a penalty-type approach. The effi...The non-Gaussian three-chain, eight-chain and full network models for rubber elasticity are cast in rate from. For computational converlency, incompressibility is incorporated through a penalty-type approach. The efficiency and accuracy of the rate forms are discussed in detail.展开更多
This paper presents a general framework that can be used to estimate direct and cross elasticities for freight transport using a network model. This methodology combines operational research (network assignments in a ...This paper presents a general framework that can be used to estimate direct and cross elasticities for freight transport using a network model. This methodology combines operational research (network assignments in a geographical information system) with more classical econometrics (multinomial logit choice models). The application of the method to a real-world case is illustrated by a simple model that relies on the generalized cost of transport as the only explanatory variable in the utility function. The methodological framework allows, however, for the implementation of more complex functions. Beside the generalized cost functions for road, rail and inland waterways transport, the network model needs origin-destination matrixes and digitized networks. They are imported from ETIS Plus, a European transport policy information system. A set of direct and cross elasticities is presented. The estimated values are obtained using two methods: the first computes standard elasticities, while the second estimates arc elasticities. Figures are presented for Europe and for a large region around the Benelux countries, where more competition exists between the three modes of interest.展开更多
This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand （SUEED） model. First, proof is given for the existence of derivatives of output variables...This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand （SUEED） model. First, proof is given for the existence of derivatives of output variables with respect to the perturbation parameters for the SUEED model. Then by taking advantage of the gradient-based method for sensitivity analysis of a general nonlinear program, detailed formulae are developed for calculating the derivatives of designed variables with respect to perturbation parameters at the equilibrium state of the SUEED model. This method is not only applicable for a sensitivity analysis of the logit-type SUEED problem, but also for the probit-type SUEED problem. The application of the proposed method in a numerical example shows that the proposed method can be used to approximate the equilibrium link flow solutions for both logit-type SUEED and probit-type SUEED problems when small perturbations are introduced in the input parameters.展开更多
While Internet traffic is currently dominated by elastic data transfers, it is anticipated that streaming applications will rapidly develop and contribute a significant amount of traffic in the near future. Therefore,...While Internet traffic is currently dominated by elastic data transfers, it is anticipated that streaming applications will rapidly develop and contribute a significant amount of traffic in the near future. Therefore, it is essential to understand and capture the relation between streaming and elastic traffic behavior. In this paper, we focus on developing simple yet effective approximations to capture this relationship. We study, then, an analytical model to evaluate the end-to-end performance of elastic traffic under multi-queuing system. This model is based on the fluid flow approximation. We assume that network architecture gives the head of priority to real time traffic and shares the remaining capacity between the elastic ongoing flows according to a specific weight.展开更多
With the growing popularity of cloud-based data center networks (DCNs),task resource allocation has become more and more important to the efficient use of resource in DCNs.This paper considers provisioning the maximum...With the growing popularity of cloud-based data center networks (DCNs),task resource allocation has become more and more important to the efficient use of resource in DCNs.This paper considers provisioning the maximum admissible load (MAL)of virtual machines (VMs)in physical machines (PMs)with underlying tree-structured DCNs using the hose model for communication.The limitation of static load distribution is that it assigns tasks to nodes in a once-and-for-all manner,and thus requires a priori knowledge of program behavior.To avoid load redistribution during runtime when the load grows,we introduce maximum elasticity scheduling,which has the maximum growth potential subject to the node and link capacities.This paper aims to find the schedule with the maximum elasticity across nodes and links.We first propose a distributed linear solution based on message passing,and we discuss several properties and extensions of the model.Based on the assumptions and conclusions,we extend it to the multiple paths case with a fat tree DCN,and discuss the optimal solution for computing the MAL with both computation and communication constraints.After that,we present the provision scheme with the maximum elasticity for the VMs,which comes with provable optimality guarantee for a fixed flow scheduling strategy in a fat tree DCN.We conduct the evaluations on our testbed and present various simulation results by comparing the proposed maximum elastic scheduling schemes with other methods.Extensive simulations validate the effectiveness of the proposed policies,and the results are shown from different perspectives to provide solutions based on our research.展开更多
文摘The non-Gaussian three-chain, eight-chain and full network models for rubber elasticity are cast in rate from. For computational converlency, incompressibility is incorporated through a penalty-type approach. The efficiency and accuracy of the rate forms are discussed in detail.
文摘This paper presents a general framework that can be used to estimate direct and cross elasticities for freight transport using a network model. This methodology combines operational research (network assignments in a geographical information system) with more classical econometrics (multinomial logit choice models). The application of the method to a real-world case is illustrated by a simple model that relies on the generalized cost of transport as the only explanatory variable in the utility function. The methodological framework allows, however, for the implementation of more complex functions. Beside the generalized cost functions for road, rail and inland waterways transport, the network model needs origin-destination matrixes and digitized networks. They are imported from ETIS Plus, a European transport policy information system. A set of direct and cross elasticities is presented. The estimated values are obtained using two methods: the first computes standard elasticities, while the second estimates arc elasticities. Figures are presented for Europe and for a large region around the Benelux countries, where more competition exists between the three modes of interest.
基金The Scientific Innovation Research of College Graduates in Jiangsu Province(No.CXLX13_110)the Young Scientists Fund of National Natural Science Foundation of China(No.51408253)the Young Scientists Fund of Huaiyin Institute of Technology(No.491713328)
文摘This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand （SUEED） model. First, proof is given for the existence of derivatives of output variables with respect to the perturbation parameters for the SUEED model. Then by taking advantage of the gradient-based method for sensitivity analysis of a general nonlinear program, detailed formulae are developed for calculating the derivatives of designed variables with respect to perturbation parameters at the equilibrium state of the SUEED model. This method is not only applicable for a sensitivity analysis of the logit-type SUEED problem, but also for the probit-type SUEED problem. The application of the proposed method in a numerical example shows that the proposed method can be used to approximate the equilibrium link flow solutions for both logit-type SUEED and probit-type SUEED problems when small perturbations are introduced in the input parameters.
文摘While Internet traffic is currently dominated by elastic data transfers, it is anticipated that streaming applications will rapidly develop and contribute a significant amount of traffic in the near future. Therefore, it is essential to understand and capture the relation between streaming and elastic traffic behavior. In this paper, we focus on developing simple yet effective approximations to capture this relationship. We study, then, an analytical model to evaluate the end-to-end performance of elastic traffic under multi-queuing system. This model is based on the fluid flow approximation. We assume that network architecture gives the head of priority to real time traffic and shares the remaining capacity between the elastic ongoing flows according to a specific weight.
基金the National Science Foundation (NSF)of United States under Grant Nos.CNS 1757533, CNS 1629746,CNS 1564128,CNS 1449860,CNS 1461932,CNS 1460971,IIP 1439672,and CSC 20163100.
文摘With the growing popularity of cloud-based data center networks (DCNs),task resource allocation has become more and more important to the efficient use of resource in DCNs.This paper considers provisioning the maximum admissible load (MAL)of virtual machines (VMs)in physical machines (PMs)with underlying tree-structured DCNs using the hose model for communication.The limitation of static load distribution is that it assigns tasks to nodes in a once-and-for-all manner,and thus requires a priori knowledge of program behavior.To avoid load redistribution during runtime when the load grows,we introduce maximum elasticity scheduling,which has the maximum growth potential subject to the node and link capacities.This paper aims to find the schedule with the maximum elasticity across nodes and links.We first propose a distributed linear solution based on message passing,and we discuss several properties and extensions of the model.Based on the assumptions and conclusions,we extend it to the multiple paths case with a fat tree DCN,and discuss the optimal solution for computing the MAL with both computation and communication constraints.After that,we present the provision scheme with the maximum elasticity for the VMs,which comes with provable optimality guarantee for a fixed flow scheduling strategy in a fat tree DCN.We conduct the evaluations on our testbed and present various simulation results by comparing the proposed maximum elastic scheduling schemes with other methods.Extensive simulations validate the effectiveness of the proposed policies,and the results are shown from different perspectives to provide solutions based on our research.
