The world population is increasing rapidly, and recent awareness of the limits of natural resources and the pollution of soil, air and water, is pushing towards a new form of agriculture, sustainable agriculture. Sust...
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The frozen food sector accounts for a significant share of the food market, a trend that is being fueled by shifting socioeconomic and technical advancements. However, the production process consumes a significant qua...
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The modernization of forest harvesting operations has significantly increased the cost of machine ownership and has turned forest harvesting into a capital-intensive process. To increase productivity and profitability...
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The modernization of forest harvesting operations has significantly increased the cost of machine ownership and has turned forest harvesting into a capital-intensive process. To increase productivity and profitability, some companies have acquired multi-task harvesting machines. While many previous papers focused on optimizing the harvest scheduling to reduce the costs of harvesting, the assignment of multi-task machines was not considered in their models. In this work, an optimization model is developed for the detailed scheduling of harvesting activities on multiple cut blocks using multi-task machines. This model is a continuation of previous work on detailed harvest scheduling. It prescribes the start time and the end time of operations of each machine at each cut block, the number of machines to be assigned for each harvesting activity at each cut block, the cut block that the machine should move to after completing its operation at a cut block, and the type of activity it should perform. It is applied to a case study of a forest company in Canada. According to the results, the total harvesting cost decreased by Can$ 25,000 when multi-task machines were used compared to exclusive machines, due to less machine movement and the need for fewer machines.
This paper looks into the issue of optimal power scheduling of multiple microgrids using hierarchical imitation learning. The system is designed to be a hierarchical learning model towards a two-level microgrid commun...
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ISBN:
(纸本)9798350354416;9798350354409
This paper looks into the issue of optimal power scheduling of multiple microgrids using hierarchical imitation learning. The system is designed to be a hierarchical learning model towards a two-level microgrid community (MGC) structure. The upper-level MGC agent uses an imitation learning algorithm to schedule exchange power between different microgrids, while lower-level microgrid agents are controlled by individual energy management systems using mixed-integer linear programming (MILP). In this paper, we focus on achieving economic dispatch in a large microgrid community while maintaining the privacy of the local microgrids. A simulation study of hierarchical imitation learning is provided based on an MGC system. Our results show the outstanding performance of the designed algorithm with a cost close to the centralized optimal results, about 10% improvement compared to the offline method, and very fast execution, which would be suitable for online power scheduling.
This study contributes to the fish reverse supply chain due to a lack of social, economic and environmental impacts. This study aims to develop a mathematical model for the fish reverse supply chain with a multi-echel...
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This study contributes to the fish reverse supply chain due to a lack of social, economic and environmental impacts. This study aims to develop a mathematical model for the fish reverse supply chain with a multi-echelon, multiple periods, and products. The model optimizes total profit, job opportunities, and carbon emissions simultaneously. The proposed model provides social-economic insight for governments and industries to understand the increasing job opportunities if fish gelatine and powder industries can process fish waste. A sensitivity analysis shows that the supply of raw fish, selling prices, and purchasing costs are sensitive to total profit, carbon emissions, and job opportunities. The results show that the total profit for five months is USD 1,437,837, and the most significant contribution to the total cost is the costs of purchasing, emission costs, and production costs, which are 43.83%, 24.02%, and 18.15%, respectively. These results can assist managers in making optimal decisions regarding raw fish supply, halal fish gelatine, and fish powder production, impacting strategic, tactical, and operational policies.
The envisioned concept of Urban Air Mobility (UAM) introduces new challenges for computing safe trajectories. A safe trajectory must ensure that a vertiport to conduct a safety landing is always within reach in the ev...
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ISBN:
(数字)9781624107160
ISBN:
(纸本)9781624107160
The envisioned concept of Urban Air Mobility (UAM) introduces new challenges for computing safe trajectories. A safe trajectory must ensure that a vertiport to conduct a safety landing is always within reach in the event of a contingency. Moreover, the trajectory must avoid any no-fly zones. Computing optimal trajectories that fulfill both requirements is particularly complicated for areas with numerous no-fly zones and vertiports because the resulting optimization problem involves continuous and discrete variables. As a consequence, the problem cannot be optimized efficiently using collocation- or shooting-based methods. Instead, we propose a linearmixed-integer-based formulation of the problem, which can be solved using mixed-integer linear programming (MILP) solvers. Our approach considers electric Vertical Take-Off and Landing aircraft (eVTOL), which can transition between vertical and wingborne flight. The capabilities of the approach are demonstrated with a two-dimensional example.
This study proposes a home healthcare routing and scheduling problem, where perishable products such as medicines, vaccines, or meals must be provided for some patients' treatments. The problem is formulated as a ...
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ISBN:
(纸本)9798350358513;9798350358520
This study proposes a home healthcare routing and scheduling problem, where perishable products such as medicines, vaccines, or meals must be provided for some patients' treatments. The problem is formulated as a mixedintegerlinearprogramming (MILP). A two-stage matheuristic is then developed as the solution approach. The first stage is a local search to solve the nurse routing problem, and the second stage is run as the relaxed MILP to solve the scheduling problem. The matheuristic is tested on newly generated instances and compared with the results of CPLEX. It is able to obtain CPLEX solutions within shorter computational times for small instances and achieve feasible solutions for larger instances.
The rapid growth of Internet-of-Things (IoT) systems demands higher throughput to process sensor data. Existing data processing platforms use simple heuristics for task placement, which perform poorly. We proposed a P...
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ISBN:
(纸本)9798350386066;9798350386059
The rapid growth of Internet-of-Things (IoT) systems demands higher throughput to process sensor data. Existing data processing platforms use simple heuristics for task placement, which perform poorly. We proposed a Permutation-based Task Placement Optimizer (PTPO) that constructs a set of valid task placement permutations to formulate a mixed-integer linear programming problem. PTPO enables efficient real-time task placement for multiple dynamic applications. Our study highlights three key design factors: joint consideration of compute and network constraints, accurate profiling of resource needs, and fine-grained splitting of tasks across nodes. We demonstrate more than 80% throughput gain compared to state-of-the-art schemes using real-world IoT Applications.
In this paper, a multi-objective optimization problem of sizing and siting power systems with the integration of electric vehicles in a distribution system is addressed. Vehicle-to-grid contribution, charging stations...
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ISBN:
(纸本)9798350387186;9798350387179
In this paper, a multi-objective optimization problem of sizing and siting power systems with the integration of electric vehicles in a distribution system is addressed. Vehicle-to-grid contribution, charging stations, renewable energy sources in the form of photovoltaic and wind turbines, and energy storage systems are considered in the proposed approach. A mixed-integer linear programming model is presented for this problem, which minimizes the total cost associated with infrastructure development and power generation while considering operational efficiency and sustainability considerations. A strategic placement of such infrastructural arrangements and their sizes can improve grid resiliency and optimally host a high penetration of electric vehicles, along with integrating renewable energy sources, is also proposed. The suitability of the proposed model is proven through a case study presented for an IEEE 24-bus distribution power system, drawing improvements in cost effectiveness, energy efficiency, and renewable energy utilization within the power grid.
This paper introduces a new formulation that finds the optimum for the Moving-Target Traveling Salesman Problem (MT-TSP), which seeks to find a shortest path for an agent, that starts at a depot, visits a set of movin...
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ISBN:
(纸本)9798350377712;9798350377705
This paper introduces a new formulation that finds the optimum for the Moving-Target Traveling Salesman Problem (MT-TSP), which seeks to find a shortest path for an agent, that starts at a depot, visits a set of moving targets exactly once within their assigned time-windows, and returns to the depot. The formulation relies on the key idea that when the targets move along lines, their trajectories become convex sets within the space-time coordinate system. The problem then reduces to finding the shortest path within a graph of convex sets, subject to some speed constraints. We compare our formulation with the current state-of-the-art mixedinteger Conic Program (MICP) formulation for the MT-TSP. The experimental results show that our formulation outperforms the MICP for instances with up to 20 targets, with up to two orders of magnitude reduction in runtime, and up to a 60% tighter optimality gap. We also show that the solution cost from the convex relaxation of our formulation provides significantly tighter lower-bounds for the MT-TSP than the ones from the MICP.
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