3,110 research outputs found
The impact of the spot price modeling on the electricity portfolio optimization problem
No full textPrevious studies in the literature have suggested that, in deregulated markets, large consumers may adopt stochastic programming for the optimization of their electricity portfolio. Nevertheless, there may be several modeling approaches, characterized by different assumptions on the stochastic behavior of the spot price. Such different approaches could lead to different solutions of the electricity portfolio optimization problem. Besides, these solutions could vary also because of the impact of the risk aversion of each large consumer. In this paper, we then investigate how different spot prices model can lead to different solutions, generalizing the Value of the Stochastic Solution (VSS). Our aim is to build a decision support system that suggests the optimal procurement policy by using the most suitable spot prices model, based on the risk aversion of the decision maker. We evaluate our technique in a realistic case study in which the portfolio optimization problem is modeled as a two-stage problem solved with the Sample Average Approximation method
Integrating multi-stage stochastic programming and machine learning for the evaluation of policies in the electricity portfolio problem
No full textMulti-stage stochastic programming can support large consumers in developing electricity portfolios that balance the expected total cost and the risk level. Nevertheless, the adoption of multi-stage stochastic programming in real-world problems is often made difficult by the high computational burden required. In this paper, we present an innovative approach, called General Policy Function Approximation, that provides good solutions to the electricity portfolio problem in a limited computational time, owing to the integration of multi-stage stochastic programming and machine learning. Our approach improves the Policy Function Approximation (PFA) approach proposed by Defourny et al. [(2012). Multi-stage stochastic programming: A scenario tree-based approach to planning under uncertainty. Decision Theory Models for Applications in Artificial Intelligence (L. E. Sucar, E. Morales, F. Eduardo & J. Hoey eds). vol. 6. Hershey: IGI Global, pp. 97–144], by developing a single policy function generated from a larger amount of data. Owing to a realistic computational campaign, we show that our approach outperforms PFA both in terms of quality of the policy obtained, and in terms of time required
Rozpor ako východisko, láska ako smer u Simone Weilovej (Contradiction as base, Love as direction in writings of Simone Weil)
No full textArticle is explaining contradiction and love, Simone Weil‘s essential terms of hermeneutics of human Being. It introduces close relation of these terms with her understanding of God as well as with her overall concept of religion. Author also mentions Simone Weil‘s inspirations with philosophical and spiritual concepts of the East
A job shop scheduling problem with human operators in handicraft production
No full textThis paper deals with complex job shop scheduling problems. A (typically large) number of elementary tasks has to be carried out, according to precedence constraints defined by a task graph. As typical of production environments such as handicraft production and task processing requires two different resources, i.e. machines and human operators. While for each operation a given machine is specified, there are in general more human operators capable of performing it. The problem is to assign the tasks to the operators, sequence them on each operator and sequence them on each machine so that the overall makespan is minimised. This scheduling problem is NP-hard even if the task graph consists of three chains (three-job job shop), and there are two fully skilled operators. We propose two heuristics for this scheduling problem, based on two different ways of decomposing the problem. An extensive computational experience allows a comparison between the heuristic solutions and the one obtained solving a mixed-integer programming formulation of the problem. The experiments show that close-to-optimal solutions can be obtained in reasonable time on a PC. Our model is applied to a case study from leather manufacturing, and we also show its use as a decision support tool in skill planning
Job shop scheduling problem with human operators in manufacturing process
No full textThis work deals with complex job shop scheduling problems, in which each task requires two different resources, i.e., machines and human operators. While a machine is specified for each task, there are in general more operators enabled to performing it. The problem is to assign and sequence the tasks for each operator and sequence them on each machine in order to minimize a certain objective function. We address both makespan minimization, for which we propose two different euristics, and the related cyclic scheduling problem, proposing a new MILP formulation
“I beg you to tell me what has become of Djamila”: The Political Mobilization of Simone de Beauvoir’s Readers During the Boupacha Affair
No full textBy Sophia Millman This is a condensed version of a Masters thesis dedicated to the political mobilization of Simone de Beauvoir’s readers. The citations from the letters were translated from French by the author. *** On June 2, 1960, the French government ordered all copies of the daily Algiers edition of Le Monde seized and destroyed to suppress the publication of Simone de Beauvoir’s article “Pour Djamila Boupacha.” Beauvoir, a self-professed “woman of letters”, not “of action[1]”, and one ..
A comparative study of form and theology in the works of Flannery O'Connor and Simone Weil
No full textIn this comparative study of the form and theology of Flannery O'Connor and Simone Weil I interrogate how Weil's philosophical writings and her theology illuminate O'Connor's use of both narrative and non-fictional forms, and her Catholicism. The Introduction analyses how Weil's concept of superposed reading provides a new method of approaching both O'Connor, her writings, and O'Connor
studies, and focuses on how such apparently different women interconnect. Chapter One explores how both Weil and O'Connor attempt to write their theologies on the
souls of their readers yet are each subject to constraints imposed by form. Weil's concept of locating equilibrium between incommensurates is discussed, and her
distinctively philosophical approach to fictions and fictionality is used to investigate O'Connor's notion of prophetic fictions and the writer's role. Chapter Two assesses how both writers revivify Christian paradoxes. Weil's monstrous concept of affiiction, and O'Connor's use of the grotesque genre to jolt secular man into an
awareness of the sacred are scrutinised. Chapter Three studies how both writers consider an encounter between God and man is possible through the action of grace. My Conclusion interrogates how Weil's work can deepen our understanding of O'Connor's writings, and examines how successful O'Connor is at realising a truly
Christian literature. I conclude that despite being a writer of powerful fictions, O'Connor can not be totally successful in her mission as writer-prophet because
ultimately fiction escapes orthodoxy
Adoption paths of digital transformation in manufacturing SME
No full textDigital transformation requires the implementation of different technologies that may improve the firms’ capability in the collection, combination, processing, and use of business data. To guarantee an adequate combination of these technologies, several maturity models have been proposed in the literature, but only a few papers have investigated the actual implementation paths adopted by firms for digital transformation. In particular, no studies have investigated the implementation paths followed by SMEs, whose limited financial and
human resources may prevent the adoption of the roadmaps developed for large firms. In this paper, we analyse the implementation paths for digital transformation adopted by a wide sample of Italian SMEs operating in different sectors. By combining Partial Least Squares Structural Equation Modelling with Necessity Condition Analysis, we clarify the specific enabler and enhancer roles played by different digital technologies. The study
sheds further light on the relationship among these technologies and their contribution to the development of SMEs’ information processing capability. In particular, our analysis shows that digital technologies associated with Industry 4.0 can be classified into four hierarchical layers, Sensor, Integration, Intelligence, and Response, that are in charge of the collection, combination, processing and use of organizational data. Our results show that
the implementation of these layers is not based on a standalone approach since the lower layers enable and enhance the adoption of the upper layers. The present paper may also offer useful insights to managers and policymakers, interested in improving the digital transformation of SMEs
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