Home healthcare companies (HHC) have emerged as vital alternatives to traditional hospitals, particularly in meeting the healthcare needs of individuals within the comfort of their homes. The COVID-19 pandemic has amp...
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The number of electric vehicles is steadily increasing of the past few years. This transition to electric vehicles bears the challenge, to integrate the charging processes into the grid without overstressing it. To pr...
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ISBN:
(数字)9781728167602
ISBN:
(纸本)9781728167602
The number of electric vehicles is steadily increasing of the past few years. This transition to electric vehicles bears the challenge, to integrate the charging processes into the grid without overstressing it. To prevent this, research has tackled lately the scheduling of electric vehicle charging. Especially the charging of electric vehicle fleets is in the focus of research. There are already different solution approaches to increase the grid stability, to increase the intake of locally produced renewable energy or simply to reduce the cost. However, all these solution approaches use different mathematical models with different parameters to represent the charging scheduling problem. This results in the problem that each model is applicable for a special use case only, other use cases might need other parameters for the scheduling of the electric vehicle fleet. To ease this problem, this paper provides a detailed mathematical model for the cost minimization of a general electric fleet in the form of a mixed-integer-linear-program. In order to do this, the paper shows that different research approaches use different parameters in their solutions. Afterwards, the paper presents a general overview of technical limitations for the electric fleets. On foundation of these limitations a mixed-integer-linear-program model for a wide range of electric fleets is established. Also, the paper provides options to extend the model in order to improve the result of an optimal schedule.
In this work we have addressed lexicographic multi-objective linearprogramming problems where some of the variables are constrained to be integer. We have called this class of problems LMILP, which stands for Lexicog...
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ISBN:
(纸本)9783030406165
In this work we have addressed lexicographic multi-objective linearprogramming problems where some of the variables are constrained to be integer. We have called this class of problems LMILP, which stands for Lexicographic mixed integer linear programming. Following one of the approach used to solve mixed integer linear programming problems, the branch and bound technique, we have extended it to work with infinitesimal/infinite numbers, exploiting the Grossone Methodology. The new algorithm, called GrossBB, is able to solve this new class of problems, by using internally the GrossSimplex algorithm (a recently introduced Grossone extension of the well-known simplex algorithm, to solve lexicographic LP problems without integer constraints). Finally we have illustrated the working principles of the GrossBB on a test problem.
This paper presents a mixed-integerlinearprogramming-based optimization model for simultaneous optimal load control and scheduling of distributed systems coupled through their energy consumptions. The subsystems are...
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ISBN:
(纸本)9781665406734
This paper presents a mixed-integerlinearprogramming-based optimization model for simultaneous optimal load control and scheduling of distributed systems coupled through their energy consumptions. The subsystems are able to adjust their energy consumption during the execution of a task and aim at minimizing their completion time and energy cost. The overall problem is solved in a distributed fashion, where each subsystem optimizes its individual operation without sharing sensitive information. To this end, dual decomposition is employed and a new algorithm to update the dual variables is presented. It relies on a transformation of the gradient of the quadratically approximated dual function and the subsequent solution of a regression problem. The proposed algorithm makes efficient use of information collected in previous iterations. The solution obtained from the distributed optimization of the subsystems is compared to both a decentral and a system-wide solution, showing that the distributed solution lies close to the global optimum of the process.
The aim of this paper is to show a novel floorplanner based on mixed-integerlinearprogramming (MILP), providing a suitable formulation that makes the problem tractable using state-of-the-art solvers. The proposed me...
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ISBN:
(纸本)9781479951116
The aim of this paper is to show a novel floorplanner based on mixed-integerlinearprogramming (MILP), providing a suitable formulation that makes the problem tractable using state-of-the-art solvers. The proposed method takes into account an accurate description of heterogeneous resources and partially reconfigurable constraints of recent FPGAs. A global optimum can be found for small instances in a small amount of time. For large instances, with a time limited search, a 20% average improvement can be achieved over floorplanners based on simulated annealing. Our approach allows the designer to customize the objective function to be minimized, so that different weights can be assigned to a linear combination of metrics such as total wire length, aspect ratio and area occupancy.
In this work, we address a task allocation problem for human multi-robot settings. Given a set of tasks to perform, we formulate a general mixed-integerlinearprogramming (MILP) problem aiming at minimizing the overa...
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ISBN:
(纸本)9781665404921
In this work, we address a task allocation problem for human multi-robot settings. Given a set of tasks to perform, we formulate a general mixed-integerlinearprogramming (MILP) problem aiming at minimizing the overall execution time while optimizing the quality of the executed tasks as well as human and robotic workload. Different skills of the agents, both human and robotic, are taken into account and human operators are enabled to either directly execute tasks or play supervisory roles;moreover, multiple manipulators can tightly collaborate if required to carry out a task. Finally, as realistic in human contexts, human parameters are assumed to vary over time, e.g., due to increasing human level of fatigue. Therefore, online monitoring is required and re-allocation is performed if needed. Simulations in a realistic scenario with two manipulators and a human operator performing an assembly task validate the effectiveness of the approach.
Optimal routing and investment decisions are key design criteria to reduce the high investment costs of district heating systems. However, these optimization problems have prohibitively high computational costs for la...
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Optimal routing and investment decisions are key design criteria to reduce the high investment costs of district heating systems. However, these optimization problems have prohibitively high computational costs for large districts. Four different mixed-integerlinear optimization frameworks are benchmarked in this study in order to compare their computational scaling. The frameworks exhibit significant differences in solving times for synthetic benchmarks and real-world urban districts of up to 9587 potential edges. The new open-source framework topotherm, developed for this work, exhibits the best computational performance when only one time step is optimized. The comparison between the models R & eacute;simont, DHmin, DHNx, and topotherm shows two main trends. First, fewer integer variables do not necessarily translate to lower solving times, and second, using redundant binary variables, which introduce symmetries into the constraints, leads to higher solving times. None of the considered optimization frameworks is able to solve the largest benchmark problems for five time steps within the allowed time limit and tolerance. These findings highlight the challenges of and pressing need to develop efficient models for simultaneous optimization of district heating network topology, pipe sizing, and operation.
Hazardous wastes have significant negative impacts on environment and people, which make their management a prominent task. A general hazardous waste reverse logistics network consists of sources, collection centers, ...
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Hazardous wastes have significant negative impacts on environment and people, which make their management a prominent task. A general hazardous waste reverse logistics network consists of sources, collection centers, treatment centers, processing/recycling facilities, and disposal facilities. We study a reverse logistics network specifically for household hazardous wastes and examine its difference from a non-hazardous and industrial waste network. We consider multiobjective mixed-integer deterministic and stochastic mathematical models that are designed to answer the following questions: which facilities or centers should be opened, which routes should be utilized, and how much waste should be transported to each location in order to minimize the transportation cost, transportation/site risk, and to maximize household convenience for the purpose of participation increase at collection stage. Specifically, we propose an optimization framework for the management of hazardous household wastes, and consider the waste paint network in the City of Toronto, Ontario, Canada as a test bed for our analysis. Finally, we provide easy-to-interpret visualization tools for the problem, which help interpreting the model outcomes and identifying policy insights.
Agile assembly systems in automotive production are predominantly characterized by decoupled and independent workstations. This raises the question how such assembly systems can be evaluated and compared against the p...
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Agile assembly systems in automotive production are predominantly characterized by decoupled and independent workstations. This raises the question how such assembly systems can be evaluated and compared against the predominantly used assembly lines. Job-shop-problems as a promising formulation do not yet offer a model that covers all the intended degrees of freedom. This research work thus presents an extended job-shop-problem and its validation while considering parallel and multifunctional workstations, sequence-dependent set-up times, routing and sequence flexibility as well as a multivariable objective function. The resulting model based on mixed integer linear programming contributes to the evaluation of agile assembly systems and supports the development of real-time capable algorithms for practical applications.
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