The Experts below are selected from a list of 87525 Experts worldwide ranked by ideXlab platform
Fulvio Simonelli - One of the best experts on this subject based on the ideXlab platform.
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limits and perspectives of effective o d matrix correction using traffic counts
Transportation Research Part C-emerging Technologies, 2009Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:Abstract Correction of the O–D matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners for improving the overall reliability of Transport models. Recently, Papola and Marzano [Papola, A., Marzano, V., 2006. How can we trust in the O–D matrix correction procedure using traffic counts? In: Proceedings of the 2006 ETC Conference, Strasbourg] showed through laboratory experiments that this procedure is generally unable to provide for effective correction of the O–D matrix. From a theoretical standpoint, this result can be justified by the lower number of (stochastic) equations (independent observed link flows) with respect to the unknowns (O–D flows). This paper first confirms that this represents the main reason for the failure of this procedure, showing that satisfactory correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, where the number of O–D pairs usually far exceeds the number of link counts, we explore alternative assumptions and contexts, allowing for a proper balance between unknowns and equations. This can be achieved by moving to within-day dynamic contexts, where a much larger number of equations are generally available. In order to bound the corresponding increase in the number of unknowns, specific reasonable hypotheses on O–D flow variation across time slices must be introduced. In this respect, we analyze the effectiveness of the O–D matrix correction procedure in the usually adopted linear hypothesis on the dynamic process evolution of O–D flows and under the assumption of constant distribution shares. In the second case it is shown that satisfactory corrections can be performed using a small number of time slices of up to 3 min in length, leading to a time horizon in which the hypothesis of constant distribution shares can be regarded as trustworthy and realistic.
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effectiveness of origin destination matrix correction procedure using traffic counts
Transportation Research Record, 2008Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:The estimation and correction of the origin-destination (O-D) matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners to improve the overall reliability of Transport models. Recently, Papola and Marzano showed through laboratory experiments that this procedure is generally not able to provide an effective correction of the O-D matrix. This result can be justified from a theoretical standpoint because of the lower number of stochastic equations (independent observed link flows) with respect to the unknowns (O-D flows). The current study confirms, first, that this circumstance represents the main reason for failure of the procedure by showing that good correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, in which the number of O-D pairs is usually much greater than the number of link counts, the study explores alternative assumptions and contexts th...
Shiyun Xiong - One of the best experts on this subject based on the ideXlab platform.
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phonon dislocation interaction and its impact on thermal conductivity
Journal of Applied Physics, 2021Co-Authors: Yajuan Cheng, Masahiro Nomura, Sebastian Volz, Shiyun XiongAbstract:This Perspective describes the phonon Transport Engineering with one-dimensional defects, i.e., dislocations, from both theoretical and experimental points of view. The classical models, modern atomistic simulations, and advanced experimental investigations on thermal conductivity reduction by dislocations are discussed. Particularly, the complex stress field induced by dislocations, the phonon–dislocation interaction mechanisms, and the anisotropic thermal Transport in materials with well-oriented dislocations are emphasized. Further investigations of phonon–dislocation interactions in both theory and experiments are prospected at the end of the work.
Vittorio Marzano - One of the best experts on this subject based on the ideXlab platform.
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limits and perspectives of effective o d matrix correction using traffic counts
Transportation Research Part C-emerging Technologies, 2009Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:Abstract Correction of the O–D matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners for improving the overall reliability of Transport models. Recently, Papola and Marzano [Papola, A., Marzano, V., 2006. How can we trust in the O–D matrix correction procedure using traffic counts? In: Proceedings of the 2006 ETC Conference, Strasbourg] showed through laboratory experiments that this procedure is generally unable to provide for effective correction of the O–D matrix. From a theoretical standpoint, this result can be justified by the lower number of (stochastic) equations (independent observed link flows) with respect to the unknowns (O–D flows). This paper first confirms that this represents the main reason for the failure of this procedure, showing that satisfactory correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, where the number of O–D pairs usually far exceeds the number of link counts, we explore alternative assumptions and contexts, allowing for a proper balance between unknowns and equations. This can be achieved by moving to within-day dynamic contexts, where a much larger number of equations are generally available. In order to bound the corresponding increase in the number of unknowns, specific reasonable hypotheses on O–D flow variation across time slices must be introduced. In this respect, we analyze the effectiveness of the O–D matrix correction procedure in the usually adopted linear hypothesis on the dynamic process evolution of O–D flows and under the assumption of constant distribution shares. In the second case it is shown that satisfactory corrections can be performed using a small number of time slices of up to 3 min in length, leading to a time horizon in which the hypothesis of constant distribution shares can be regarded as trustworthy and realistic.
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effectiveness of origin destination matrix correction procedure using traffic counts
Transportation Research Record, 2008Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:The estimation and correction of the origin-destination (O-D) matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners to improve the overall reliability of Transport models. Recently, Papola and Marzano showed through laboratory experiments that this procedure is generally not able to provide an effective correction of the O-D matrix. This result can be justified from a theoretical standpoint because of the lower number of stochastic equations (independent observed link flows) with respect to the unknowns (O-D flows). The current study confirms, first, that this circumstance represents the main reason for failure of the procedure by showing that good correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, in which the number of O-D pairs is usually much greater than the number of link counts, the study explores alternative assumptions and contexts th...
Marcello Montanino - One of the best experts on this subject based on the ideXlab platform.
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a new look at planning and designing Transportation systems a decision making model based on cognitive rationality stakeholder engagement and quantitative methods
Transport Policy, 2015Co-Authors: Ennio Cascetta, Armando Carteni, Francesca Pagliara, Marcello MontaninoAbstract:Transportation systems are complex sociotechnical systems and this dual nature is reflected in the literature dealing with their planning, i.e. defining courses of action from both public and private points of view. On the one hand, the social sciences literature makes it clear that most decisions related to Transportation are “wicked”, i.e. they cannot be tackled with traditional Engineering approaches since they are poorly defined. On the other, Transportation systems have a strong technical component affecting most of such decisions, as they have to (or should) comply with compelling technical and economic requirements. The literature on Transport Engineering and economics deals with Transportation planning mostly as a rational process based on the formulation and comparison of alternative options.
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a new look at planning and designing Transportation systems a decision making model based on cognitive rationality stakeholder engagement and quantitative methods
Transport Policy, 2015Co-Authors: Ennio Cascetta, Armando Carteni, Francesca Pagliara, Marcello MontaninoAbstract:Transportation systems are complex sociotechnical systems and this dual nature is reflected in the literature dealing with their planning, i.e. defining courses of action from both public and private points of view. On the one hand, the social sciences literature makes it clear that most decisions related to Transportation are "wicked", i.e. they cannot be tackled with traditional Engineering approaches since they are poorly defined. On the other, Transportation systems have a strong technical component affecting most of such decisions, as they have to (or should) comply with compelling technical and economic requirements. The literature on Transport Engineering and economics deals with Transportation planning mostly as a rational process based on the formulation and comparison of alternative options. In this paper, we propose an approach to planning and designing Transportation systems, at least in the more complex cases, meant to bridge the gap between social and technical points of view. The proposed approach is cross-disciplinary, as it integrates notions from cognitive sciences, organization and management sciences with Transportation systems analysis. Transportation planning, both under public and private market-oriented viewpoints, is seen as a complex decision-making process where different actors (decision-makers, stakeholders, professionals) interact in different contexts and according to different "models" or approaches. After a brief discussion of the main elements of most planning processes and of the different decision making models, the paper proposes a decision-making model based on three parallel and intertwined processes: a cognitive rational approach to organizing the decision-making process, a five-level stakeholder engagement process, and a revised role of quantitative analyses and methods drawing on tools from Engineering and economics, amongst other disciplines. We also present a real application of the proposed decision-making model to the case study of the Regional Metro System (RMS) project in Campania (southern Italy), where a complex decisional context with different stakeholders and multiple (often contrasting) interests was managed in the integrated framework for over a decade, resulting in the largest and most effective of such projects in Italy. Finally, the paper proposes new roles and new challenges for quantitative analyses and mathematical tools to support participated decision-making processes, extending their well-established functions for designing and assessing Transportation solutions. Language: en
Andrea Papola - One of the best experts on this subject based on the ideXlab platform.
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limits and perspectives of effective o d matrix correction using traffic counts
Transportation Research Part C-emerging Technologies, 2009Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:Abstract Correction of the O–D matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners for improving the overall reliability of Transport models. Recently, Papola and Marzano [Papola, A., Marzano, V., 2006. How can we trust in the O–D matrix correction procedure using traffic counts? In: Proceedings of the 2006 ETC Conference, Strasbourg] showed through laboratory experiments that this procedure is generally unable to provide for effective correction of the O–D matrix. From a theoretical standpoint, this result can be justified by the lower number of (stochastic) equations (independent observed link flows) with respect to the unknowns (O–D flows). This paper first confirms that this represents the main reason for the failure of this procedure, showing that satisfactory correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, where the number of O–D pairs usually far exceeds the number of link counts, we explore alternative assumptions and contexts, allowing for a proper balance between unknowns and equations. This can be achieved by moving to within-day dynamic contexts, where a much larger number of equations are generally available. In order to bound the corresponding increase in the number of unknowns, specific reasonable hypotheses on O–D flow variation across time slices must be introduced. In this respect, we analyze the effectiveness of the O–D matrix correction procedure in the usually adopted linear hypothesis on the dynamic process evolution of O–D flows and under the assumption of constant distribution shares. In the second case it is shown that satisfactory corrections can be performed using a small number of time slices of up to 3 min in length, leading to a time horizon in which the hypothesis of constant distribution shares can be regarded as trustworthy and realistic.
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effectiveness of origin destination matrix correction procedure using traffic counts
Transportation Research Record, 2008Co-Authors: Vittorio Marzano, Andrea Papola, Fulvio SimonelliAbstract:The estimation and correction of the origin-destination (O-D) matrix from traffic counts is a classical procedure usually adopted in Transport Engineering by practitioners to improve the overall reliability of Transport models. Recently, Papola and Marzano showed through laboratory experiments that this procedure is generally not able to provide an effective correction of the O-D matrix. This result can be justified from a theoretical standpoint because of the lower number of stochastic equations (independent observed link flows) with respect to the unknowns (O-D flows). The current study confirms, first, that this circumstance represents the main reason for failure of the procedure by showing that good correction is generally obtained when the number of equations is greater than the number of unknowns. Then, since this circumstance does not occur in practice, in which the number of O-D pairs is usually much greater than the number of link counts, the study explores alternative assumptions and contexts th...
