Motivated by a real situation arising in the Brazilian sugarcane industry, this paper addresses the integrated planning of harvesting and transport operations over a multi-period planning horizon. The aim is to develo...
详细信息
Motivated by a real situation arising in the Brazilian sugarcane industry, this paper addresses the integrated planning of harvesting and transport operations over a multi-period planning horizon. The aim is to develop a tactical plan for the deployment of harvesting and transport equipment that sets the periods for the execution of the harvesting operations on the sugarcane fields and the type of harvesting machines and road haulage vehicles to be operated. These decisions are made subject to multiple constraints related to the projected crop yield, resource availability, demand for sugarcane at the mills and further technical requirements specific to the harvesting operations. The tactical plan to be determined minimizes the total cost incurred by the equipment used and the total time required to harvest all the fields. We propose a bi-objective mixed-integer non-linear programming model for this new problem. A computational study is conducted for test instances capturing the characteristics of a Brazilian milling company. Pareto-optimal solutions are identified by the Progressive Bounded Constraint method that is extended to the problem at hand. A comparative analysis highlights the trade-offs between economic performance and harvesting efficiency, thereby supporting the decision maker in making a more informed choice of the preferred tactical plan. Useful managerial insights are also provided into the profile of the harvesting and transport resources that should be used under different weather conditions and work schedules.
This study investigates the additional installation of a high-speed diesel generator to independent microgrids (MG) such as remote islands where relatively efficient medium-speed diesel generators (DGs) are mainly use...
详细信息
This study investigates the additional installation of a high-speed diesel generator to independent microgrids (MG) such as remote islands where relatively efficient medium-speed diesel generators (DGs) are mainly used. While small-sized and lightweight, high-speed DGs are not widely spread for continuous usage because their efficiency is lower than that of the medium-speed DGs. The objective of this study is to evaluate the performance of the new method of load sharing optimization to improve the economy by interconnecting a high-speed DG to an independent MG where the medium-speed DGs are operated. The study investigates the effect of operation cost reduction by installing the new load sharing method of operation following the load sharing pattern derived by the mixed-integer programming. As a result of this study, there was some effect to installing a high-speed DG operated by the conventional method. In addition, by adding the new method of load sharing with optimization, the economic effect became even higher.
The paper considers the assignment of items to groups according to their attribute values such that the groups are as balanced as possible. Although the problem is in general NP-hard, we prove that it can be solved in...
详细信息
The paper considers the assignment of items to groups according to their attribute values such that the groups are as balanced as possible. Although the problem is in general NP-hard, we prove that it can be solved in pseudo-polynomial time if attribute values are integer. We point out a relation to partition and more general to multi-way number partitioning. Furthermore, we introduce a mixed-integer programming (MIP) formulation, a variable reduction technique, and an efficient lower bound for the objective value. Our computational results show that the lower bound meets the optimal objective value in the most of our instances of realistic size. Hence, the MIP solves instances with several thousand items within seconds to optimality.
As the first-generation Battery Electric Vehicles (BEVs) reach the end of use life, the disposal of retired batteries raised significant economic and environmental concerns. To alleviate these problems, reusing retire...
详细信息
As the first-generation Battery Electric Vehicles (BEVs) reach the end of use life, the disposal of retired batteries raised significant economic and environmental concerns. To alleviate these problems, reusing retired BEV batteries on other applications such as off-grid photovoltaic (PV) systems with integrated energy storage system is a promising direction to give them a “second-life”. Although reuse Second-life Batteries (SLB) reduces cost of PV systems, significant challenges such as battery performance degradation caused by aging still need to be tackled. This paper utilizes Genetic Algorithm (GA) to minimize total cost of an off-grid PV system by optimizing the solar array size, SLB size, and starting state of health of SLBs simultaneously. The battery dynamics, aging, and performance degradation are modeled and integrated into the problem. Additionally, a real-world BEV charging dataset from 39 state parks in Tennessee is used to validate the performance of the algorithm in off-grid PV charger applications. The simulation results exhibit the algorithm can minimize total cost while ensuring battery performance. An economic analysis is performed comparing with the use of new batteries, and it is found that utilizing SLB for off-grid PV charger gives an average of 49.19% cost saving.
This paper addresses a critical question pertaining to manufacturing sustainability: is it economically viable to implement an island microgrid to power a flow shop system under power demand and supply uncertainty? Th...
详细信息
This paper addresses a critical question pertaining to manufacturing sustainability: is it economically viable to implement an island microgrid to power a flow shop system under power demand and supply uncertainty? Though many studies on microgrid sizing are available, the majority assume the microgrid is interconnected with main grid. This paper aims to size wind turbine, photovoltaic and battery storage to energize a multi-stage flow shop system in island mode. A mixed-integer, non-linear programming model is formulated to optimize the renewable portfolio and capacity with the goal of minimizing the levelized cost of energy. The island microgrid is tested in three locations with diverse climate profiles. The results show that net zero energy flow shop production is economically feasible in the areas where the average wind speed exceed 8 m/s at 80-meter tower height, or the battery cost drops below $100,000/MWh. Sensitivity analyses are further carried out with respect to installation cost, demand response program, production scalability, and weather seasonality.
We revisit and enhance previous work pertaining to the use of polyhedral potential fields for motion planning in a receding horizon framework. We adapt the standard vertex-based mixed-integer (MI) representations of p...
详细信息
We revisit and enhance previous work pertaining to the use of polyhedral potential fields for motion planning in a receding horizon framework. We adapt the standard vertex-based mixed-integer (MI) representations of piecewise affine functions and propose three equivalent formulations which balance the complexity of the geometric representation with the size of the associated MI representation. In all cases, we arrive at formulations whose polyhedral support comes (either directly or as a refinement of it) from an associated hyperplane arrangement induced by the hyperplanes bounding the polyhedral obstacles.
In hyperthermia treatments, cancer tissue is heated to enhance the desired effects of radio- and chemotherapies. A powerful technology for noninvasive feedback-controlled hyperthermia is magnetic-resonance-guided high...
详细信息
In hyperthermia treatments, cancer tissue is heated to enhance the desired effects of radio- and chemotherapies. A powerful technology for noninvasive feedback-controlled hyperthermia is magnetic-resonance-guided high-intensity focused ultrasound (MR-HIFU), which enables fast and millimeter-accurate heating inside the body. Electronic beam steering allows for volumetric heating, but due to its limited steering range can only be used to treat small tumors. For the treatment of larger tumors, the transducer itself must be mechanically relocated as well. Due to system limitations, however, the admissible transducer positions must be restricted to a finite set that is chosen a priori. Moreover, non-negligible time is needed for transducer relocation, during which no heating is possible. In this paper, we present a mixed-integer model predictive controller that simultaneously optimizes over the power deposition by electronic beam steering - a continuous subproblem - as well as the mechanical transducer motions - a discrete subproblem. By incorporating model knowledge of the tissue’s thermal response and of the transducer carrier motion system into the predictive algorithm, the controller optimizes treatment temperature while respecting temperature and actuation constraints. The performance of the proposed feedback control setup is demonstrated by means of simulation.
Periodic timetabling for railway networks is usually modeled by the Periodic Event Scheduling Problem (PESP). This model permits to express many requirements that practitioners impose on periodic railway timetabl...
详细信息
E-commerce and retail companies are seeking ways to cut delivery times and costs by exploring opportunities to use drones for making last mile delivery deliveries. In recent years, drone routing and scheduling has bec...
详细信息
E-commerce and retail companies are seeking ways to cut delivery times and costs by exploring opportunities to use drones for making last mile delivery deliveries. In recent years, drone routing and scheduling has become a highly active area of research. This research addresses the delivery concept of a truck-drone combination along with the idea of allowing autonomous drones to fly from delivery trucks, make deliveries, and fly to delivery trucks nearby. The proposed model considers the synchronized truck drone routing model by allowing multiple drones to fly from a truck, serve customers and immediately return to the same truck for the battery swap and package retrieval. The model also takes into account both trucks and drones capacities to ensure that the amount of loads carried by each drone must not exceed its capacity and the total amount of loads in each delivery route must be less than truck’s capacity. The goal is to find the optimal routes of both trucks and drones which minimize the total arrival time of both trucks and drones at the depot after completing the deliveries. The problem can be solved by the formulated mixedintegerprogramming (MIP) for the small size problem. Numerical results in the case study and benchmark problems are presented to show the delivery time improvement over the delivery time from other delivery types.
Combining an exact method with a heuristic approach possibilities for solving linear mixedinteger optimization problems are investigated. For the considered exact method numerical results with problems from the pract...
详细信息
Combining an exact method with a heuristic approach possibilities for solving linear mixedinteger optimization problems are investigated. For the considered exact method numerical results with problems from the practice are given. Proper heuristic methods are the interior path methods [2] for which numerical experiences are well-known or the so-called geometric approach [8], Deriving of sufficient conditions for the existence of feasible solutions is possible.
暂无评论