In this paper, we study the cyclic scheduling problem for electroplating lines where products are loaded into the system at one end and unloaded at the other end. The electroplating jobs must be processed within a giv...
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In this paper, we study the cyclic scheduling problem for electroplating lines where products are loaded into the system at one end and unloaded at the other end. The electroplating jobs must be processed within a given time window in each tank. There is no buffer between tanks. Two hoists sharing a common track are used to move products between the tanks in the production line. The objective is to minimize the production cycle time through scheduling hoist moves. A solution procedure is proposed in this study. The production line is first divided into two non-overlapping zones with a hoist assigned to each zone. Then a mixed integer linear programming model is developed for scheduling hoist moves. Computational results on a benchmark example problem are given in the paper to demonstrate the application of the proposed method.
This paper presents a scheme to achieve structural and operational optimization for the heat plant in a district energy system. A district energy system consists of energy suppliers and consumers, district heating pip...
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This paper presents a scheme to achieve structural and operational optimization for the heat plant in a district energy system. A district energy system consists of energy suppliers and consumers, district heating pipelines and heat storage facilities in a region. Production and consumption of energy and transport of energy as well as storage of heat are taken into account in the model. The problem is formulated as a mixed integer linear programming (MILP) problem where the objective is to minimize the overall cost of the district energy system. Evaluation of the energy production cost is based on the daily operation for every season at the plant located at Suseo in Seoul, Korea. From the results of numerical simulations we can see that the district energy system is well approximated by the proposed model, and that the energy efficiency is improved by the application of the optimal operation conditions provided by the proposed model.
In this article, we consider a public power service in the liberalized market, operating its own power plant and participating in the spot market. In the short-term horizon, the objective is to optimize the dispatch o...
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ISBN:
(纸本)9781424442409
In this article, we consider a public power service in the liberalized market, operating its own power plant and participating in the spot market. In the short-term horizon, the objective is to optimize the dispatch of the power plant in discreet steps. The public service has to meet the demand of its customers, while trading in the spot market where transaction costs apply. The power plant operation is subject to several technical constraints, as minimum down-/up-time, ramping constraints, minimum operation level constraints, minimum/maximum production per day, and the costs are given by the start-up costs, the operational cost following an efficiency curve and CO2 emission cost. This problem is modeled through a mixed integer linear programming (MILP) formulation.
In this paper, we consider the combined task of determining a favorable machine configuration and line balancing for a single assembly line where a single type of PCB is assembled with a set of interconnected, reconfi...
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ISBN:
(纸本)9781424448692
In this paper, we consider the combined task of determining a favorable machine configuration and line balancing for a single assembly line where a single type of PCB is assembled with a set of interconnected, reconfigurable machine modules. First, we formulate the problem as a non-linearintegerprogramming model with the objective of minimizing the cycle time. Then we transform it into a linear model to obtain the solution. Finally, we illustrate the effectiveness of the model by numerical tests and compare the optimal solution from our model with evolutionary algorithm.
In this work point coverage, sink location and data routing problems are considered in an integrated way and two new mixedintegerprogramming formulations are proposed. Since these models are computationally difficul...
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ISBN:
(纸本)9781424444236
In this work point coverage, sink location and data routing problems are considered in an integrated way and two new mixedintegerprogramming formulations are proposed. Since these models are computationally difficult to solve, a hierarchical solution procedure is proposed. In the top level, best sensor locations are sought by variable neighbourhood search. Given the sensor locations, a simpler formulation can be obtained and a Lagrangean Heuristic is used to solve the sink location and data routing model efficiently. Experimental results indicate that the performance of hierarchical solution approach is very good.
The medical waste management is of great importance because of the potential environmental hazards and public health risks. Manufacturers have to collect the medical waste and control its recovery or disposal. Medical...
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ISBN:
(纸本)9783642048425
The medical waste management is of great importance because of the potential environmental hazards and public health risks. Manufacturers have to collect the medical waste and control its recovery or disposal. Medical waste recovery, which encompasses reusing, remanufacturing and materials recycling, requires a specially structured reverse logistics network in order to collect the medical waste efficiently. This paper presents a mixed integer linear programming model with minimizing costs for medical waste reverse logistics networks. The total costs for reverse logistics include transportation cost, fixed cost of opening the collecting centers and processing centers and operation cost at these facilities over finite planning horizons. An improved genetic algorithm method with a hybrid encoding rule is used to solve the proposed model. The efficiency and practicability of the proposed model is validated by an application to an illustrative example dealing with medical waste returned from some hospitals to a given manufacture.
Greece's electricity market is divided in two zones, North and South, due to a generation-consumption system configuration that creates a significant transmission bottleneck from North to South. Clearly, a zonal p...
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ISBN:
(纸本)9781424444540
Greece's electricity market is divided in two zones, North and South, due to a generation-consumption system configuration that creates a significant transmission bottleneck from North to South. Clearly, a zonal pricing approach for energy provides the right incentive for the installation of new generation near consumption, if the zonal configuration reflects actual system and operational conditions. In this paper, we extend the zonal approach to include the time response-based ancillary services (also called "reserves"), which are commodities that are traded in the day-ahead market and are co-optimized with energy. We focus on the Day-Ahead Scheduling (DAS) market problem, which we formulate as a Security-Constrained Unit-Commitment problem whose objective is to co-optimize energy and reserves, taking into account the generation units' commitment costs. We model the DAS market problem as a mixed-integerlinearprogramming problem that is solved every day, simultaneously for all 24 hours of the next day. Dual analysis of the problem and calculation of shadow prices provides useful insight on how prices for each commodity are set in the presence of binding resource, transmission or zonal reserve constraints. We use a simplified model of the Greek electricity system that includes only thermal plants to illustrate the developed methodology, the resulting market solutions and unit schedules, and the energy and ancillary services marginal prices. We also analyze and discuss issues such as the interaction between the commodities of energy and ancillary services under the marginal pricing approach.
This paper addresses the cyclic multi-hoist scheduling problem. The problem arises in automated electroplating lines where multiple hoists are operating on a shared track. The considered processing sequences may be di...
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ISBN:
(纸本)9781424427932
This paper addresses the cyclic multi-hoist scheduling problem. The problem arises in automated electroplating lines where multiple hoists are operating on a shared track. The considered processing sequences may be different from the location sequence of the tanks and may contain loops, i.e. multiple usages of single tanks within a sequence. In addition the electroplating line may be equipped with identical tanks used as parallel resources. A mixed integer linear programming (MILP) formulation for optimizing the cycle time is developed considering in particular collisions of hoists, loops in the process sequence and parallel tanks. The developed model is tested and evaluated using a real world example indicating that the presented solution finds optimal cyclic schedules in reasonable time.
This paper presents two modeling approaches for hatching and scheduling jobs on parallel non-identical machines. For scheduling of jobs the due dates as a hard restriction and machine dependent processing times are co...
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ISBN:
(纸本)9781424427932
This paper presents two modeling approaches for hatching and scheduling jobs on parallel non-identical machines. For scheduling of jobs the due dates as a hard restriction and machine dependent processing times are considered. Between each of the jobs a setup may be necessary or not, depending on the predecessor. The setup of the machines is done by a single worker who needs to be scheduled as well, since only he can serve one machine at a lime. The objective is to maximize the overall workload of the machines meeting the constraint of the due dates. While the first approach uses mixed integer linear programming to calculate an optimal schedule, the second one uses a simulation, based on colored Petri nets. Both methods are tested and evaluated using illustrative simulation examples.
The aim of this work is to design intra-daily recourse strategies which may be used by operators to decide in real-time the modifications to bring to planned generation schedules of a set of units in order to respond ...
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ISBN:
(纸本)9781424422340
The aim of this work is to design intra-daily recourse strategies which may be used by operators to decide in real-time the modifications to bring to planned generation schedules of a set of units in order to respond to deviations from the forecasted operating scenario. Our aim is to design strategies that are interpretable by human operators, that comply with real-time constraints and that cover the major disturbances that may appear during the next day. To this end we propose a new framework using supervised learning to infer such recourse strategies from simulations of the system under a sample of conditions representing possible deviations from the forecast. This framework is validated on a realistic generation system of medium size.
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