Due to the fact that headway is a key factor to be considered in bus scheduling, this paper proposes a bi-level programming model for optimizing bus headway in public transit lines. In this model, with the interests o...Due to the fact that headway is a key factor to be considered in bus scheduling, this paper proposes a bi-level programming model for optimizing bus headway in public transit lines. In this model, with the interests of bus companies and passengers in mind, the upper-level model＇s objective is to minimize the total cost, which is affected by frequency settings, both in time and economy in the transit system. The lower-level model is a transit assignment model used to describe the assignment of passengers＇ trips to the network based on the optimal bus headway. In order to solve the proposed model, a hybrid genetic algorithm, namely the genetic algorithm and the simulated annealing algorithm （GA-SA）, is designed. Finally, the model and the algorithm are tested against the transit data, by taking some of the bus lines of Changzhou city as an example. Results indicate that the proposed model allows supply and demand to be linked, which is reasonable, and the solving algorithm is effective.展开更多
Generalized linear mixed models(GLMMs)have been widely used in contemporary ecology studies.However,determination of the relative importance of collinear predictors(i.e.fixed effects)to response variables is one of th...Generalized linear mixed models(GLMMs)have been widely used in contemporary ecology studies.However,determination of the relative importance of collinear predictors(i.e.fixed effects)to response variables is one of the challenges in GLMMs.Here,we developed a novel R package,glmm.hp,to decompose marginal R2^(2)explained by fixed effects in GLMMs.The algorithm of glmm.hp is based on the recently proposed approach‘average shared variance’i.e.used for multivariate analysis.We explained the principle and demonstrated the use of this package by simulated dataset.The output of glmm.hp shows individual marginal R2^(2)s that can be used to evaluate the relative importance of predictors,which sums up to the overall marginal R2^(2).Overall,we believe the glmm.hp package will be helpful in the interpretation of GLMM outcomes.展开更多
In this study, an efficient hybrid model is proposed to simulate the fluid flow in the reservoirs with multi-scale fractures, which cannot be easily modeled by neither the continuum models nor the discrete fracture mo...In this study, an efficient hybrid model is proposed to simulate the fluid flow in the reservoirs with multi-scale fractures, which cannot be easily modeled by neither the continuum models nor the discrete fracture models. In the proposed method, the small fractures are modeled by using an improved Multiple Sub-Region method, which can capture the strongly anisotropy of fracture elements and the effects of border region on the transmissibility and provide more accurate results, on the other hand, the large fractures are modeled explicitly as major fluid conduits by the Embedded Discrete Fracture Model. Then, an efficient numerical algorithm based on the Mimetic Finite Difference method is developed to solve the hybrid method. At the end, several numerical examples are carried out to verify the accuracy and applicability of the proposed numerical model.展开更多
基金The National Natural Science Foundation of China(No.50978057)the National Key Technology R& D Program of China duringthe 11th Five-Year Plan Period (No.2006BAJ18B03)+1 种基金the Scientific Research Foundation of Graduate School of Southeast University ( No.YBJJ1013)the Program for Postgraduates Research Innovation in University of Jiangsu Province(No.CX09B 060Z)
文摘Due to the fact that headway is a key factor to be considered in bus scheduling, this paper proposes a bi-level programming model for optimizing bus headway in public transit lines. In this model, with the interests of bus companies and passengers in mind, the upper-level model＇s objective is to minimize the total cost, which is affected by frequency settings, both in time and economy in the transit system. The lower-level model is a transit assignment model used to describe the assignment of passengers＇ trips to the network based on the optimal bus headway. In order to solve the proposed model, a hybrid genetic algorithm, namely the genetic algorithm and the simulated annealing algorithm （GA-SA）, is designed. Finally, the model and the algorithm are tested against the transit data, by taking some of the bus lines of Changzhou city as an example. Results indicate that the proposed model allows supply and demand to be linked, which is reasonable, and the solving algorithm is effective.
基金This work was supported by the National Natural Science Foundation of China(32271551)the Metasequoia funding of Nanjing Forestry University.Conflict of interest statement.The authors declare that they have no conflict of interest.
文摘Generalized linear mixed models(GLMMs)have been widely used in contemporary ecology studies.However,determination of the relative importance of collinear predictors(i.e.fixed effects)to response variables is one of the challenges in GLMMs.Here,we developed a novel R package,glmm.hp,to decompose marginal R2^(2)explained by fixed effects in GLMMs.The algorithm of glmm.hp is based on the recently proposed approach‘average shared variance’i.e.used for multivariate analysis.We explained the principle and demonstrated the use of this package by simulated dataset.The output of glmm.hp shows individual marginal R2^(2)s that can be used to evaluate the relative importance of predictors,which sums up to the overall marginal R2^(2).Overall,we believe the glmm.hp package will be helpful in the interpretation of GLMM outcomes.
基金supported by the National Natural Science Foundation of China(Grant Nos.51404292,51234007,61573018,51504277)the Shandong Provincial Natural Science Foundation,China(Grant Nos.ZR2014EEQ010,ZR2015EL014)+1 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.15CX05037A,14CX06091A,14CX05027A)the Innovative Project of China University of Petroleum(Grant No.YCXJ2016015)
文摘In this study, an efficient hybrid model is proposed to simulate the fluid flow in the reservoirs with multi-scale fractures, which cannot be easily modeled by neither the continuum models nor the discrete fracture models. In the proposed method, the small fractures are modeled by using an improved Multiple Sub-Region method, which can capture the strongly anisotropy of fracture elements and the effects of border region on the transmissibility and provide more accurate results, on the other hand, the large fractures are modeled explicitly as major fluid conduits by the Embedded Discrete Fracture Model. Then, an efficient numerical algorithm based on the Mimetic Finite Difference method is developed to solve the hybrid method. At the end, several numerical examples are carried out to verify the accuracy and applicability of the proposed numerical model.
