scholarly journals Demand Responsive Service-based Optimization on Flexible Routes and Departure Time of Community Shuttles

2020 ◽  
Vol 12 (3) ◽  
pp. 897 ◽  
Author(s):  
Jie Xiong ◽  
Biao Chen ◽  
Xiangnan Li ◽  
Zhengbing He ◽  
Yanyan Chen
Keyword(s):  
Time Window ◽  
Mixed Integer ◽  
Neighborhood Search ◽  
Total System ◽  
Integer Optimization ◽  
On Demand ◽  
Route Length ◽  
Departure Time ◽  
Mixed Integer Optimization Model ◽  
Vehicle Capacity

This paper investigates the optimal routing design problem of a community shuttle system feeding to metro stations based on demand-responsive service. The solution aims to jointly optimize a set of customized routes and the departure time of each route to provide a flexible shuttle service. Considering a set of on-demand trip requests between bus stops and metro stations, a mixed-integer optimization model is formulated to minimize the total system cost, including the operation cost and passenger’s in-vehicle cost, subject to the constraints on the route length, time window, detours, and vehicle capacity. To solve the problem, two metaheuristic algorithms, i.e. a tabu search (TS) and a variable neighborhood search (VNS), with different internal operators are specifically designed. A case study based on a realistic network is conducted to test the model and the solution, and comparisons of the performance of different algorithms are investigated.

scholarly journals Optimal Pump Scheduling for Urban Drainage under Variable Flow Conditions

Resources ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 73 ◽  
Author(s):  
Oreste Fecarotta ◽  
Armando Carravetta ◽  
Maria Morani ◽  
Roberta Padulano
Keyword(s):  
Power Efficiency ◽  
Drainage System ◽  
Mixed Integer ◽  
Urban Drainage ◽  
Integer Optimization ◽  
Average Value ◽  
Computational Performance ◽  
Set Up ◽  
Mixed Integer Optimization Model ◽  
Inflow Discharge

The paper is focused on the optimal scheduling of a drainage pumping station, complying with variations in the pump rotational speed and a recurrent pattern for the inflow discharge. The paper is structured in several consecutive steps. In the first step, the experimental set-up is described and results of calibration tests on different pumping machines are presented to obtain equations linking significant variables (discharge, head, power, efficiency). Then, those equations are utilized to build a mixed-integer optimization model able to find the scheduling solution that minimizes required pumping energy. The model is solved with respect to a case study referred to a urban drainage system in Naples (Italy) and optimization results are analysed to provide insights on the algorithm computational performance and on the influence of pumping machine characteristics on the overall efficiency savings. With reference to the simulated scenarios, an average value of 32% energy can be saved with an optimized control. Its actual value depends on the hydraulic characteristics of the system.

scholarly journals Combining retrosynthesis and mixed-integer optimization for minimizing the chemical inventory needed to realize a WHO essential medicines list

2020 ◽  
Vol 5 (2) ◽  
pp. 367-376
Author(s):  
Hanyu Gao ◽  
Connor W. Coley ◽  
Thomas J. Struble ◽  
Linyan Li ◽  
Yujie Qian ◽  
...  
Keyword(s):  
Essential Medicines ◽  
Mixed Integer ◽  
Integer Optimization ◽  
Mixed Integer Optimization ◽  
Essential Medicines List ◽  
Multiple Products ◽  
On Demand

Retrosynthetic pathways suggestions are optimized to minimize the number of unique chemicals required to synthesize multiple products as would be useful for on-demand manufacturing.

Optimization on Supply Chain Network Based on High-Tech Products Life Cycle

2013 ◽  
Vol 416-417 ◽  
pp. 1920-1925
Author(s):  
Lei Zhang ◽  
Yan Yan Kong
Keyword(s):  
Life Cycle ◽  
Profit Maximization ◽  
Transportation Cost ◽  
Pso Algorithm ◽  
Mixed Integer ◽  
High Tech ◽  
Integer Optimization ◽  
Time Model ◽  
Decision Variables ◽  
Mixed Integer Optimization Model

In view of the characteristics of market demands of high-tech products life cycle at all stages, the response time model of the products life cycle at all stages was established according to the differences of products stage response points. Based on this, the production cost/time, transportation cost/time, shortage cost, sales price, and other factors of the products life cycle at all stages were taken into consideration. The 0-1 mixed integer optimization model of multi-factory and multi-distribution center with profit maximization as the optimization objective was established. Particle Swarm Optimization (PSO) algorithm was used to solve the decision variables. Finally, a numerical example was used to illustrate the practical application value of this model.

scholarly journals Recent Advancements in Commercial Integer Optimization Solvers for Business Intelligence Applications

2021 ◽  
Author(s):  
Cheng Seong Khor
Keyword(s):  
Business Intelligence ◽  
Mixed Integer Linear Programming ◽  
Branch And Cut ◽  
Mixed Integer ◽  
Neighborhood Search ◽  
Integer Optimization ◽  
Computational Performance ◽  
Solution Methods ◽  
Future Work ◽  
Optimization Solvers

The chapter focuses on the recent advancements in commercial integer optimization solvers as exemplified by the CPLEX software package particularly but not limited to mixed-integer linear programming (MILP) models applied to business intelligence applications. We provide background on the main underlying algorithmic method of branch-and-cut, which is based on the established optimization solution methods of branch-and-bound and cutting planes. The chapter also covers heuristic-based algorithms, which include preprocessing and probing strategies as well as the more advanced methods of local or neighborhood search for polishing solutions toward enhanced use in practical settings. Emphasis is given to both theory and implementation of the methods available. Other considerations are offered on parallelization, solution pools, and tuning tools, culminating with some concluding remarks on computational performance vis-à-vis business intelligence applications with a view toward perspective for future work in this area.

Towards the Implementation of Optimal Train Loading Plan in the Athens-Thessaloniki Freight Services

2017 ◽  
Vol 8 (3) ◽  
pp. 39-53
Author(s):  
Athanasios Ballis ◽  
Fillipos Karapetis ◽  
Theocharis Ballis
Keyword(s):  
Information System ◽  
Daily Basis ◽  
Operating Conditions ◽  
Mixed Integer ◽  
Integer Optimization ◽  
Container Transport ◽  
Railway Infrastructure ◽  
Mixed Integer Optimization Model ◽  
Pragmatic Aspects ◽  
Train Loading

The main goal of train loading optimization is the proper assignment of loading units onto the wagons, taking under consideration numerous factors like the maximum axle load restrictions, the condition of the railway infrastructure, the operating conditions, safety regulations etc. The typical expression of the problem is usually formulated under one of the two following assumptions: (a) the commodity load is predefined or (b) the number and type of wagons is fixed. The current work describes the steps that were followed and enabled the analysis, optimization and integration of the train loading plan into the information system that supports the new railway service of TRAINOSE for containers transport on the Athens – Thessaloniki line. This new service, named iCS, was launched in December 2013 and ever since operates on a daily basis. The work includes a literature review, a mention of the pragmatic aspects that influence container transport and train loading plan, the presentation of the heuristic which is implemented in the information system of iCS service, a validation process against a mixed integer optimization model and finally concludes with the proposed solution for the iCS wagon loading problem.

An optimization model for selecting wood supply contracts

2020 ◽  
Vol 50 (4) ◽  
pp. 399-412 ◽  
Author(s):  
Ali Rahimi ◽  
Mikael Rönnqvist ◽  
Luc LeBel ◽  
Jean-François Audy
Keyword(s):  
Optimization Model ◽  
Wood Fiber ◽  
Pulp And Paper ◽  
Raw Material ◽  
Mixed Integer ◽  
Integer Optimization ◽  
Paper Mills ◽  
Wood Supply ◽  
Portfolio Strategies ◽  
Mixed Integer Optimization Model

Procurement for forest companies with pulp and paper mills aims to ensure that a sufficient volume of wood supply enters the production process. Numerous suppliers and contract types are available; however, their selection is a complex decision for procurement managers. In addition, managers typically dedicate a portion of their wood fiber demand to each group of suppliers, which is referred to as a portfolio strategy. Despite the available literature in contract selection, the consideration of contract types and their characteristics have not been addressed for the complex procurement process. In this study, a mixed-integer optimization model is proposed to best select contracts for pulp and paper procurement. The challenge was to plan deliveries in each time period to satisfy the demand of raw material at the mills. The potential of this model is demonstrated with a case study based on characteristics from a forest company in Quebec, Canada. A comparison between traditional fixed and flexible contracts is presented. Different portfolio strategies are also evaluated for groups of suppliers to investigate potential improvements.

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