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Author: Lu Lu (S.M.) Publisher: ISBN: Category : Languages : en Pages : 111
Book Description
The off-line calibration is a crucial step for the successful application of Dynamic Traffic Assignment (DTA) models in transportation planning and real time traffic management. While traditional approaches focus on the separate or sequential estimation of demand and supply in a DTA system, a recently proposed framework calibrates the demand and supply models simultaneously by formulating the off-line calibration as a constrained optimization problem. Simultaneous Perturbation Stochastic Approximation (SPSA) has been reported in the literature to be the most suitable solution algorithm for this problem due to its highly efficient gradient estimation approach. However, it turns out that the performance of SPSA in terms of convergence rate and long run accuracy can deteriorate significantly when the physical network size and the number of considered time intervals increase. To overcome this problem, this thesis proposes a new algorithm, called Weighted SPSA, or W-SPSA. W-SPSA improves SPSA's gradient estimation process by effectively reducing the noise generated by irrelevant measurements. Synthetic tests are performed to systematically compare the performance of SPSA and W-SPSA. W-SPSA shows scalability and robustness in the tests and outperforms SPSA under different problem scales and characteristics. The application of W-SPSA in real world large-scale DTA systems is demonstrated with a case study of the entire Singapore expressway network. Results show that WSPSA is a more suitable algorithm than SPSA for the off-line calibration of large-scale DTA models. The contributions of the thesis include: 1) identifying limitations of a state-of-the- art solution algorithm for the DTA off-line calibration problem, 2) presenting rigorous definitions of an enhanced algorithm and proposing approaches to estimate the required algorithm parameters, 3) systematically comparing the performance of the new algorithm against the state-of-the-art, 4) demonstrating the characteristics of the new algorithm through experiments, and 5) discussing the general steps and empirical technical considerations when tackling real world DTA off-line calibration problems.
Author: Lu Lu (S.M.) Publisher: ISBN: Category : Languages : en Pages : 111
Book Description
The off-line calibration is a crucial step for the successful application of Dynamic Traffic Assignment (DTA) models in transportation planning and real time traffic management. While traditional approaches focus on the separate or sequential estimation of demand and supply in a DTA system, a recently proposed framework calibrates the demand and supply models simultaneously by formulating the off-line calibration as a constrained optimization problem. Simultaneous Perturbation Stochastic Approximation (SPSA) has been reported in the literature to be the most suitable solution algorithm for this problem due to its highly efficient gradient estimation approach. However, it turns out that the performance of SPSA in terms of convergence rate and long run accuracy can deteriorate significantly when the physical network size and the number of considered time intervals increase. To overcome this problem, this thesis proposes a new algorithm, called Weighted SPSA, or W-SPSA. W-SPSA improves SPSA's gradient estimation process by effectively reducing the noise generated by irrelevant measurements. Synthetic tests are performed to systematically compare the performance of SPSA and W-SPSA. W-SPSA shows scalability and robustness in the tests and outperforms SPSA under different problem scales and characteristics. The application of W-SPSA in real world large-scale DTA systems is demonstrated with a case study of the entire Singapore expressway network. Results show that WSPSA is a more suitable algorithm than SPSA for the off-line calibration of large-scale DTA models. The contributions of the thesis include: 1) identifying limitations of a state-of-the- art solution algorithm for the DTA off-line calibration problem, 2) presenting rigorous definitions of an enhanced algorithm and proposing approaches to estimate the required algorithm parameters, 3) systematically comparing the performance of the new algorithm against the state-of-the-art, 4) demonstrating the characteristics of the new algorithm through experiments, and 5) discussing the general steps and empirical technical considerations when tackling real world DTA off-line calibration problems.
Author: L. May Publisher: Springer Science & Business Media ISBN: 9400940599 Category : Science Languages : en Pages : 367
Book Description
The fourth international rotifer symposium was Wednesday afternoon a tour of Edinburgh, includ held in Edinburgh, Scotland, August 18 - 25, 1985, ing a visit to the Palace of Holyrood, was arranged. hosted by the Institute of Terrestrial Ecology. This This was followed by an evening banquet with meeting continued the tradition of holding rotifer traditional Scottish entertainment. On Thursday symposia at three-year intervals. The first an evening most participants attended a fireworks dis nouncement of the fourth meeting was circulated at play which was part of the Edinburgh Festival. Fi the end of 1983 to almost 300 people whose names nally, an excursion to Loch Lomond and the Tros appeared on the mailing list of the international sach hills was arranged for the Saturday after the newsletter, Rotifer News. In total, 68 people from meeting. 23 countries attended the meeting. It is interesting The organisers would like to thank Mr. C. J. to note that, of these 68 participants, 21 had at Place and colleagues at the Institute of Terrestrial tended the first meeting, held in Linz, Austria, Ecology for their invaluable help in organising the 1976, and 13 had attended all three previous meet meeting and preparing the symposium volume for ings. publication. We are also grateful for financial sup As in previous symposia, some research topics port from the Royal Society, the British Council were identified in advance of the meeting as being and British Petroleum (Scotland).
Author: S. Bhatnagar Publisher: Springer ISBN: 1447142853 Category : Technology & Engineering Languages : en Pages : 310
Book Description
Stochastic Recursive Algorithms for Optimization presents algorithms for constrained and unconstrained optimization and for reinforcement learning. Efficient perturbation approaches form a thread unifying all the algorithms considered. Simultaneous perturbation stochastic approximation and smooth fractional estimators for gradient- and Hessian-based methods are presented. These algorithms: • are easily implemented; • do not require an explicit system model; and • work with real or simulated data. Chapters on their application in service systems, vehicular traffic control and communications networks illustrate this point. The book is self-contained with necessary mathematical results placed in an appendix. The text provides easy-to-use, off-the-shelf algorithms that are given detailed mathematical treatment so the material presented will be of significant interest to practitioners, academic researchers and graduate students alike. The breadth of applications makes the book appropriate for reader from similarly diverse backgrounds: workers in relevant areas of computer science, control engineering, management science, applied mathematics, industrial engineering and operations research will find the content of value.
Author: Publisher: ISBN: Category : Advertising Languages : en Pages : 494
Book Description
Advertising expenditure data across ten media: consumer magazines, Sunday magazines, newspapers, outdoor, network television, spot television, syndicated television, cable television, network radio, and national spot radio. Lists brands alphabetically and shows total ten media expenditures, media used, parent company and PIB classification for each brand. Also included in this report are industry class totals and rankings of the top 100 companies of the ten media.
Author: Lu Lu (S.M.)
Author: Lu Lu (S.M.)
Author: L. May
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Author: 
Author: S. Bhatnagar
Author: George Goudie Chisholm
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Author: Japan. Kishōchō
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