scholarly journals A Branch and Bound Algorithm for the Exact Solution of the Problem of EMU Circulation Scheduling in Railway Network

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Chao Lu ◽  
Lei-shan Zhou ◽  
Yi-xiang Yue ◽  
Ran Chen

This paper is concerned with the scheduling of Electrical Multiple Units (EMUs) under the condition of their utilization on one sector or within several interacting sectors. Based on the introduction of the train connection graph which describes the possible connection relationship between trains, the integer programming model of EMU circulation planning is constructed. In order to analyzing the resolution of the model, a heuristic which shares the characteristics with the existing methods is introduced first. This method consists of two stages: one is a greedy strategy to construct a feasible circulation plan fragment, and another is to apply a stochastic disturbance to it to generate a whole feasible solution or get a new feasible solution. Then, an exact branch and bound method which is based on graph designing is proposed. Due to the complexity, the lower bound is computed through a polynomial approximation algorithm which is a modification from the one solving the degree constraint minimum 1-tree problem. Then, a branching strategy is designed to cope with the maintenance constraints. Finally, we report extensive computational results on a railway corridor in which the sectors possess the basic feature of railway networks.

2020 ◽  
Vol 31 (4) ◽  
pp. 114
Author(s):  
Waleed Mohammed Elaibi

The importance of branch and bound algorithm is the mathematical improvement to find the value of (X) that Maximize or minimize the objective function within a set of feasible solution, as it is reliable on the efficient evaluation of the bounds of regions or branches of the space of the research, whether they are upper or lower. In this paper, we discussed five cases with respect to branching decisions based on network solutions to calculate the nearest link with a short time. From the results, bound and branch algorithm can develop and change the obtaining solutions for the five cases under study.


2017 ◽  
Vol 11 ◽  
pp. 74
Author(s):  
Lukáš Týfa ◽  
David Vodák

The paper first describes high speed rail generally and explains the relationship between high speed and conventional railway networks (according to the vehicle types in operation on the network). The core of the paper is comprised of the methodology for choosing the best route for a railway line and its application to the high speed railway connection Praha – Brno. The Algorithm used assumes the existence of more route proposals, which could be different in terms of the operational conception, line routing or types of vehicles used. The optimal variant is the one with the lowest daily cost, which includes infrastructure and vehicle costs; investment and operational costs. The results from applying this model confirmed the assumption, that a dedicated high speed railway line, only for high speed trains, has the same or lower investment costs than a line for both high speed and conventional trains. Furthermore, a dedicated high line also has a lower cost for infrastructure maintenance but a higher cost for buying high speed multiple units.


2014 ◽  
Vol 18 (1) ◽  
pp. 22-35 ◽  
Author(s):  
Domenico Celenza ◽  
Fabrizio Rossi

Purpose – The aim of this paper is to investigate the relationship between corporate performance and Value Added Intellectual Coefficient (VAICTM) on the one hand, and the relationship between the variations in market value and the variations in VAIC on the other hand. Design/methodology/approach – Starting from the VAIC model, 23 Italian listed companies were examined with the aim of investigating the relationship between VAIC and the performance of the firms in the sample. The analysis was divided into two stages. In the first stage, eight models of linear regression were estimated to verify the presence of a positive and statistically significant relationship between M/BV and VAIC and between accounting performance indicators (ROE, ROI, ROS) and the VAIC. In the second stage, six other models were tested, considering as an independent variable the variations in VAIC and the variations in profitability indicators. Findings – The outcomes of the application stress the importance of VAIC in the explanation of the variations in MV and its role as “additional coefficient” in the analysis of equity performance. Originality/value – This methodology highlights some very interesting aspects. In particular, whereas the relationship between M/BV and VAIC and between profitability indicators (ROI, ROE, ROS) and VAIC is statistically insignificant, the subsequent analysis highlights the importance of VAIC as a variable capable of increasing the explanatory power of the regression in a cross-sectional perspective.


2012 ◽  
Vol 27 (2) ◽  
pp. 187-219 ◽  
Author(s):  
Shu-Heng Chen ◽  
Chia-Ling Chang ◽  
Ye-Rong Du

AbstractThis paper reviews the development of agent-based (computational) economics (ACE) from an econometrics viewpoint. The review comprises three stages, characterizing the past, the present, and the future of this development. The first two stages can be interpreted as an attempt to build the econometric foundation of ACE, and, through that, enrich its empirical content. The second stage may then invoke a reverse reflection on the possible agent-based foundation of econometrics. While ACE modeling has been applied to different branches of economics, the one, and probably the only one, which is able to provide evidence of this three-stage development is finance or financial economics. We will, therefore, focus our review only on the literature of agent-based computational finance, or, more specifically, the agent-based modeling of financial markets.


Author(s):  
Ю.В. Ковалева

Представлен историографический анализ развития понятия большие социальные группы и историко-психологический анализ социальных феноменов , связанных с массовыми общественными явлениями в России. Сформулированы актуальные проблемы психологии больших социальных групп, к которым относятся неоднородность оснований для их выделения, недостаточная дифференцированность со сходными понятиями, неравномерность исследований в различные временные периоды и идеологическая нагруженность их разработки. Данная работа была ответом на необходимость восполнения знаний о процессах в таких группах, происходивших в различные исторические периоды развития социальной психологии, с соответствующим им уровнем научного осмысления, а также обобщением этой целостной картины на уровне современного понимания и формулировка перспективных направлений исследований. Целью исследования является установление связи между определением и основными свойствами понятия «большие социальные группы» (его синонимов, аналогов) и особенностями социальной ситуации в определенный период времени, а также реконструкция социальных процессов данного исторического этапа. Проверялась гипотеза о том, что большие социальные группы как феномены социальной жизни формировались в соответствии с историческим временем, а соответствующее им понятие и его свойства с одной стороны отвечали уровню развития гуманитарного знания, а с другой - пытались удовлетворить общественный и политический запрос в объяснении и управлении социальной ситуацией. Использовались методы историографии социальной психологии и психолого-исторической реконструкции . Первая часть статьи посвящена анализу первых двух этапов развития социальной психологии - с середины XIX до начала XX вв. и в 1920-е гг. XX в. The historiographic analysis of the development of the concept of large social groups and historical and psychological study of social phenomena associated with mass social phenomena was presented. Topical problems of the psychology of large social groups are formulated, including heterogeneity of the grounds for their isolation, insufficient differentiation with similar concepts, uneven research in various periods, and ideological loading of the history of its development. The study's main problem was the need to replenish the processes in such groups that took place in various historical periods of social psychology development as well as a synthesis of this holistic picture at the level of modern understanding and the formulation of promising areas of research. The study's purpose was to establish a connection between the definition and the basic properties of the concept of "large social groups" (and its synonyms, analogs) and the peculiarities of the social situation in a certain period, as well as the reconstruction of social processes of this historical segment. The hypothesis was tested that large social groups as phenomena of social life were formed under the past time. The concept and its properties were corresponding to them, on the one hand, compared to the level of development of humanitarian knowledge. On the other, they tried to satisfy the social and political requests to understand and manage the social situation. Methods of the historiography of the history of social psychology and psychological and historical reconstruction were used. The article's first part was devoted to the analysis of the early two stages of the development of social psychology - from the middle of the XIX to the beginning of the XX centuries and 1920 of the XX century.


2021 ◽  
Vol 24 (1) ◽  
pp. 157-183
Author(s):  
Никита Андреевич Катаев

Automation of parallel programming is important at any stage of parallel program development. These stages include profiling of the original program, program transformation, which allows us to achieve higher performance after program parallelization, and, finally, construction and optimization of the parallel program. It is also important to choose a suitable parallel programming model to express parallelism available in a program. On the one hand, the parallel programming model should be capable to map the parallel program to a variety of existing hardware resources. On the other hand, it should simplify the development of the assistant tools and it should allow the user to explore the parallel program the assistant tools generate in a semi-automatic way. The SAPFOR (System FOR Automated Parallelization) system combines various approaches to automation of parallel programming. Moreover, it allows the user to guide the parallelization if necessary. SAPFOR produces parallel programs according to the high-level DVMH parallel programming model which simplify the development of efficient parallel programs for heterogeneous computing clusters. This paper focuses on the approach to semi-automatic parallel programming, which SAPFOR implements. We discuss the architecture of the system and present the interactive subsystem which is useful to guide the SAPFOR through program parallelization. We used the interactive subsystem to parallelize programs from the NAS Parallel Benchmarks in a semi-automatic way. Finally, we compare the performance of manually written parallel programs with programs the SAPFOR system builds.


This paper discusses various optimization algorithm design techniques. So, optimization techniques which are discussed in this paper are greedy method, dynamic programming and branch and bound. Problem comes under optimization are used to find either maximum or minimum. All these techniques we have multiple inputs and some constraints and we have to find feasible solution using these inputs and constraints. In greedy method we follow some predefined method. Using that predefined method, we reach to the solution. On contrary to this in dynamic programming we take decision at every step and in the end we reach to the solution. In branch and bound we create state space tree and explore all possibilities of live node. Based on some constraint we start killing some alive nodes. Here, firstly I will discuss all the design techniques. Then types of problems that can be solved under each design techniques and their time complexities.


2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Qin Zhang ◽  
Xiaoning Zhu ◽  
Li Wang ◽  
Shuai Wang

The optimization problems of train timetabling and platforming are two crucial problems in high-speed railway operation; these problems are typically considered sequentially and independently. With the construction of high-speed railways, an increasing number of interactions between trains on multiple lines have led to resource assignment difficulties at hub stations. To coordinate station resources for multiline train timetables, this study fully considered the resources of track segments, station throat areas, and platforms to design a three-part space-time (TPST) framework from a mesoscopic perspective to generate a train timetable and station track assignment simultaneously. A 0-1 integer programming model is proposed, whose objective is to minimize the total weighted train running costs. The construction of a set of incompatible vertexes and links facilitates the expression of difficult constraints. Finally, example results verify the validity and practicability of our proposed method, which can generate conflict-free train timetables with a station track allocation plan for multiple railway lines at the same time.


Author(s):  
Guansong Lu ◽  
Zhiming Zhou ◽  
Yuxuan Song ◽  
Kan Ren ◽  
Yong Yu

CycleGAN is capable of learning a one-to-one mapping between two data distributions without paired examples, achieving the task of unsupervised data translation. However, there is no theoretical guarantee on the property of the learned one-to-one mapping in CycleGAN. In this paper, we experimentally find that, under some circumstances, the one-to-one mapping learned by CycleGAN is just a random one within the large feasible solution space. Based on this observation, we explore to add extra constraints such that the one-to-one mapping is controllable and satisfies more properties related to specific tasks. We propose to solve an optimal transport mapping restrained by a task-specific cost function that reflects the desired properties, and use the barycenters of optimal transport mapping to serve as references for CycleGAN. Our experiments indicate that the proposed algorithm is capable of learning a one-to-one mapping with the desired properties.


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