This study presents a new two-stage stochastic programming decision model for assessing how to introduce some new manufacturing technology into any generic supply and distribution chain. It additionally determines the...
详细信息
This study presents a new two-stage stochastic programming decision model for assessing how to introduce some new manufacturing technology into any generic supply and distribution chain. It additionally determines the optimal degree of postponement, as represented by the so-called customer order decoupling point (CODP), while assuming uncertainty in demand for multiple products. To this end, we propose here the formulation of a generic supply chain through an oriented graph that represents all the deployable alternative technologies, which are defined through a set of operations that are characterised by lead times and cost parameters. Based on this graph, we develop a mixed integer two-stage stochastic programme that finds the optimal manufacturing technology for meeting each market's demand, each operation's optimal production quantity, and each selected technology's optimal CODP. We also present and analyse a case study for introducing additive manufacturing technologies.
Simultaneous stochastic optimisation frameworks provide a method for optimising long-term production schedules in mining complexes that aim to maximise net present value and manage risk related to supply uncertainty. ...
详细信息
Simultaneous stochastic optimisation frameworks provide a method for optimising long-term production schedules in mining complexes that aim to maximise net present value and manage risk related to supply uncertainty. The uncertainty and local variability related to the quality and quantity of material in the mineral deposits are modelled with a set of stochastic orebody simulations, an input into the simultaneous stochastic optimisation framework. Infill drilling provides opportunities to collect additional information associated with the mineral deposits, which can inform future production scheduling decisions. A framework is developed for optimising infill drilling locations with a criterion that seeks areas that directly affect long-term planning decisions and requires the use of geostatistical simulations. Actor-critic reinforcement learning is applied to identify infill drilling locations in a copper mining complex using this criterion. The case study demonstrates that adapting production scheduling decisions given additional information has the potential to improve the associated production and financial forecasts and identifies a stable area for infill drilling.
Waste Incineration Power Plant (WIPP) is a promising sustainable and environmentally-friendly generation technique. This paper explores the impacts of WIPPs as black-start resources on distribution network restoration...
详细信息
This paper presents a novel optimal offering framework to incorporate hydrogen system potential for frequency regulation goals. Furthermore, the presented model considers the possibility of submitting bids for a day-a...
详细信息
With the gradual increase of the proportion of renewable energy generation dominated by wind power and photovoltaic power and the change of load characteristics, the source-load uncertainty of power system will be one...
详细信息
We construct an optimal investment portfolio model with deferred annuities for an individual investor saving in a retirement plan. The objective function consists of power utility in terms of consumption of all secure...
详细信息
We construct an optimal investment portfolio model with deferred annuities for an individual investor saving in a retirement plan. The objective function consists of power utility in terms of consumption of all secured retirement income from the deferred annuity purchases, as well as bequest from remaining wealth invested in equity, bond, and cash funds. The asset universe is governed by a vector autoregressive model incorporating the Nelson-Siegel term structure and equity returns. We use multi-stage stochastic programming to solve the optimization problem numerically. Deferred annuity purchases are made continuously over the working lifetime of the investor, increasing particularly in the years before retirement. The investment strategy hedges price changes in deferred annuities, and bond holding and deferred annuity purchases increase when interest rates are high. Optimal investment and deferred annuity choices depend on realized and expected values of state variables. The optimal strategy is also compared with typical retirement plan strategies such as glide paths. Our results provide support for deferred annuities as a major source of retirement income. (C) 2021 Elsevier B.V. All rights reserved.
Inspired by the global supply chain disruptions caused by the COVID-19 pandemic, we study optimal procurement and inventory decisions for a pharmaceutical supply chain over a finite planning horizon. To model disrupti...
详细信息
Inspired by the global supply chain disruptions caused by the COVID-19 pandemic, we study optimal procurement and inventory decisions for a pharmaceutical supply chain over a finite planning horizon. To model disruption, we assume that the demand for medical drugs is uncertain and shows spatiotemporal variability. To address demand uncertainty, we propose a two-stage optimization framework, where in the first stage, the total cost of pre-positioning drugs at distribution centers and its associated risk is minimized, while the second stage minimizes the cost of recourse decisions (e.g., reallocation, inventory management). To allow for different risk preferences, we propose to capture the risk of demand uncertainty through the expectation and worst-case measures, leading to two different models, namely (risk-neutral) stochastic programming and (risk-averse) robust optimization. We consider a finite number of scenarios to represent the demand uncertainty, and to solve the resulting models efficiently, we propose L-shaped decomposition-based algorithms. Through extensive numerical experiments, we illustrate the impact of various parameters, such as travel time, product's shelf life, and waste due to transportation and storage, on the supply chain resiliency and cost, under optimal risk-neutral and risk-averse policies. These insights can assist decision makers in making informed choices.
. Control of many real-life systems strongly relies on the knowledge of a domain expert, who usually adopts a safe control policy to deal with uncertainty. The term safe means that the policy is aimed at avoiding sys...
详细信息
ISBN:
(纸本)9783031248658
. Control of many real-life systems strongly relies on the knowledge of a domain expert, who usually adopts a safe control policy to deal with uncertainty. The term safe means that the policy is aimed at avoiding system’s disruptions or relevant deviations from the desired behaviour, usually at the cost of sub-optimal performances. This paper proposes a statistically-sound approach which exploits the collected experience to safe-explore new policies by assuming a reasonable risk in terms of safety while improving performances. Gaussian Process regression is the core of the approach, providing a probabilistic approximation of both system’s dynamics and performances, depending on historical data related to the application of the safe policy. Being a probabilistic model, Gaussian Process provides both an estimate of the level of safety and, more important, the associated predictive uncertainty, which is crucial for implementing the safe-exploration of new efficient policies. The approach allows to avoid the typically expensive implementation of a digital twin of the system, required in the case of simulation-optimization approaches, as well as the formulation as a stochastic programming problem. Results on two case studies, inspired by real-life systems, are presented, showing an improvement in terms of performances with respect the initial safe policy, with reasonable safety of the systems.
This paper proposes a strategy for reporting the intraday output plan of photovoltaic (PV) power plants considering the power correction of energy storage devices. First, an intraday PV power scenario generation metho...
详细信息
Remanufacturing through circular economy conserves energy and materials while creating economic growth and employment. Thus, it is imperative to develop better systems that optimise the use of resources, maximise the ...
详细信息
Remanufacturing through circular economy conserves energy and materials while creating economic growth and employment. Thus, it is imperative to develop better systems that optimise the use of resources, maximise the value of the product, and minimise the total cost. Towards this, we present a two-stage stochastic linear model for a make-to-order hybrid manufacturing-remanufacturing production system by integrating capacity and inventory decisions. We consider the uncertainty in demand, core returns rate and yield to impose flexibility as both operations are considered with a collective production capacity on the same assembly line. We have considered a setting where demand for new and remanufactured products does not cannibalise each other's demand (e.g. new parts for original equipment and remanufactured parts for independent aftermarket). Further, the capacity utilisation by core returns is considered in two ways: less capacity intensive case and more capacity intensive case. The developed model is solved for optimal inventory and capacity levels along with production quantities by maximising utilisation of resources and profit. We also present a closed-form solution by demand space partition to deduce the optimal policy of the firm. Based on our analysis, we have presented settings where remanufacturing can perfectly substitute manufacturing.
暂无评论