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On force fields for molecular dynamics simulations of crystalline silica

computationAL MATERIALS SCIENCE 2015年 107卷 88-101页

作者： Cowen, Benjamin J. El-Genk, Mohamed S. Univ New Mexico Inst Space & Nucl Power Studies Albuquerque NM 87131 USA Univ New Mexico Dept Nucl Engn Albuquerque NM 87131 USA Univ New Mexico Dept Mech Engn Albuquerque NM 87131 USA Univ New Mexico Chem & Biol Engn Dept Albuquerque NM 87131 USA

This paper reviews and examines interatomic potentials or force fields for molecular dynamics (MD) simulation of crystalline silica. The investigated potentials are the BKS, Pedone, Munetoh, TTAM, and CHIK. The calculated values of the lattice constants, density, radial and bond-angle distribution functions, equations of state, and phase transitions using different potentials are compared to experimental values for polymorphs of silica: quartz, cristobalite, coesite, and stishovite. Simulation results with the BKS potential accurately predict the experimental measurements to within 2%, and converge within a reasonable timeframe on an average workstation. The Pedone potential, also parameterized for other metallic oxides, computationally is slightly more expensive and is not as accurate. The simulations with both the CHIK and TTAM potentials are less accurate than with the BKS potential for modeling silica over the entire range of the phase diagram. The simulations with the Munetoh potential are by far the cheapest in terms of the modest computational requirements, but unsuitable for modeling crystalline silica. It could not produce the nature of the alpha-beta and I-II phase transitions in quartz or the equation of state for stishovite silica, and the predicted structural properties sometimes differ from experimental values by more than 10%. (C) 2015 Elsevier B.V. All rights reserved.

关键词： MD simulations Force fields Potentials Crystalline silica Phase transition computation time

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Block Condensing for Fast Nonlinear MPC with the Dual Newton Strategy

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IFAC-PapersOnLine 2015年第23期48卷 26-31页

作者： Kouzoupis, D. Quirynen, R. Frasch, J.V. Diehl, M. Department of Microsystems Engineering University of Freiburg Germany Department of Electrical Engineering KU Leuven Belgium Department of Mathematics Magdeburg University Germany

A recently proposed quadratic programming (QP) solver dedicated to bandstructured optimal control problems as they may arise in the field of model predictive control (MPC) is the dual Newton strategy, as implemented in the publicly available software qpDUNES. Such a structure-exploiting solver is often preferable over the use of condensing for problems with long horizons. In this paper, we propose an effcient and exible algorithm for real-time nonlinear MPC which tries to combine the advantages of the two approaches by means of a block condensing technique. Using a nontrivial benchmarking problem, we show that this approach can improve the performance of the dual Newton strategy by a factor of 10 in terms of total computation times while reducing the delay between state estimate and feedback even further. Additionally, an open-source implementation of the resulting scheme is provided as part of the ACADO code generation tool. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Predictive control systems Benchmarking Model predictive control Nonlinear systems Numerical methods Open source software Open systems Optimal control systems Quadratic programming Benchmarking problems Code generation tools computation time Nonlinear MPC Open source implementation Optimal control problem Predictive control State estimates

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Multi-agent model-based predictive control for large-scale urban traffic networks using a serial scheme

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IET CONTROL THEORY AND APPLICATIONS 2015年第3期9卷 475-484页

作者： Zhou, Zhao De Schutter, Bart Lin, Shu Xi, Yugeng Shanghai Jiao Tong Univ Dept Automat Shanghai 200240 Peoples R China Minist Educ China Key Lab Syst Control & Informat Proc Shanghai 200240 Peoples R China Delft Univ Technol Delft Ctr Syst & Control NL-2628 CD Delft Netherlands Univ Chinese Acad Sci Sch Comp & Control Engn Beijing 100049 Peoples R China

Urban traffic networks are large-scale systems, consisting of many intersections controlled by traffic lights and interacting connected links. For efficiently regulating the traffic flows and mitigating the traffic congestion in cities, a network-wide control strategy should be implemented. Control of large-scale traffic networks is often infeasible by only using a single controller, that is, in a centralised way, because of the high dimension, complicated dynamics and uncertainties of the system. In this study, the authors propose a multi-agent control approach using a congestion-degree-based serial scheme. Each agent employs a model-based predictive control approach and communicates with its neighbours. The congestion-degree-based serial scheme helps the agents to reach an agreement on their decisions regarding traffic control actions as soon as possible. A simulation study is carried out on a hypothetical large-scale urban traffic network based on the presented control strategy. The results illustrate that this approach has a better performance with regard to computation time compared with the centralised control method and a faster convergence speed compared with the classical parallel scheme.

关键词： road traffic control predictive control multi-agent systems large-scale systems computational complexity convergence traffic lights traffic flows traffic congestion mitigation network-wide control strategy multi-agent control approach congestion-degree-based serial scheme traffic control actions hypothetical large-scale urban traffic network computation time centralised control method convergence speed parallel scheme model-based predictive control approach

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The Zebra Puzzle and Getting to Know Your Tools 19

The Zebra Puzzle and Getting to Know Your Tools

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19th IEEE International Conference on Intelligent Engineering Systems (INES)

作者： Gregor, Michal Zabovska, Katarina Smatanik, Vladimir Univ Zilina Dept Control & Informat Syst Univ 8215-1 Zilina 01026 Slovakia Univ Zilina Fac Management Sci & Informat Zilina 01026 Slovakia

ISBN: (纸本)9781467379397

This papers deals with modelling of the zebra puzzle (also known as Einstein's riddle) in Prolog, the logical programming language. It shows how to construct a rudimentary representation of the puzzle in Prolog and then proceeds by suggesting several modifications that significantly reduce the amount of computation time required to solve it. The results illustrate why - if a correct and reasonably efficient knowledge representation is to be constructed - it may be vital for the knowledge engineer to have a firm understanding of the way in which their knowledge representation tool reasons. Naturally, the paper also includes the answer to the eternal question: who owns the zebra?

关键词： PROLOG knowledge representation logic programming Einstein riddle Prolog computation time knowledge representation tool logical programming language zebra puzzle Context Dairy products Electronic mail Knowledge representation Logic programming Positron emission tomography Yttrium PROLOG Knowledge Representation Logic programming computational time electronic mail Dairy products zebras Rare earths yttrium logic programming languages PET Scan

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Modified HYPR Algorithm - A Promising Technique for Low Dose Imaging 5

Modified HYPR Algorithm - A Promising Technique for Low Dose...

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IEEE International Advance Computing Conference (IACC 2015)

作者： Desai, Shrinivas D. Kulkarni, Linganagouda BVB Coll Engn & Technol Dept IS&E Hubballi 580031 India Vivekanad Inst Technol Puttur 574203 Dakshina Kannad India

ISBN: (纸本)9781479980475

Medical imaging has grown tremendously over years. The CT and MRI are well thought-out to be most extensively used imaging modalities. MRI is less dangerous, but one cannot underrate the unsafe side effects of CT. Current study reveals the actuality of escalating risk of cancer as side effect for patients who go through recurring CT scanning. Consequently the devise of low dose imaging protocol is of the enormous significance in the current scenario. In this paper we present modified highly constrained back projection (M-HYPR) as a most promising method to address low dose imaging. HYPR is basically an iterative process in nature and hence computational greedy, and is the root cause for being neglected by CT developers. The weight matrix module, being main reason for huge computation time is modified in this work. Considerable speed up factor is recorded, as compared original HYPR (O-HYPR) on a lone thread CPU implementation. The superiority of reconstructed image in each platform has been analyzed. The evidenced results convey substantial improved performance by M-HYPR algorithm, and appreciable usage of GPU in medical image applications.

关键词： Low dose imaging HYPR computation time GPU Radon transform

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A Sequential Online 3D Reconstruction System Using Dense Stereo Matching 15

A Sequential Online 3D Reconstruction System Using Dense Ste...

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IEEE Winter Conference on Applications of Computer Vision (WACV 2015)

作者： Yamao, Sosuke Miura, Mamoru Sakai, Shuji Ito, Koichi Aoki, Takafumi Tohoku Univ Grad Sch Informat Sci Sendai Miyagi 980 Japan

ISBN: (纸本)9781479966837

This paper proposes a sequential online 3D reconstruction system using dense stereo matching for a non-expert user, which can sequentially reconstruct accurate and dense 3D point clouds when the new image is captured. The proposed system is based on a novel processing pipeline of sequential online 3D reconstruction with two key techniques: (i) camera parameter estimation of Structure from Motion (SfM) and (ii) dense stereo correspondence matching using Phase-Only Correlation (POC). The user can confirm the reconstruction result and add supplementary images to the system in order to reconstruct a complete 3D model as needed. Through a set of experiments, the proposed system exhibits efficient performance in terms of reconstruction accuracy and computation time compared with the conventional system.

关键词： cameras correlation methods image capture image matching image reconstruction parameter estimation solid modelling stereo image processing 3D point cloud reconstruction POC SfM camera parameter estimation complete 3D model reconstruction computation time dense stereo correspondence matching phase-only correlation sequential online 3D reconstruction system structure from motion supplementary images Accuracy Cameras Estimation Image reconstruction Solid modeling Stereo image processing Three-dimensional displays Stereo image processing entity modeling three-dimensional displays image capture Cameras image reconstruction computational time correlation methods image matching Particulate organic carbon POMC Gene Parameter estimation

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Path Planning Algorithm for Manipulators based on an improved Backtracking Search Algorithm 5

Path Planning Algorithm for Manipulators based on an improve...

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5th International Conference on IT Convergence and Security (ICITCS)

作者： Islam, Md. Nazrul Gallardo-Alvardo, Jaime Ahmad, Othman bin Hj Mamat, Mazlina Binti Ghosh, B. K. UMS Fac Engn Kota Kinabalu Sabah Malaysia Inst Tecnol Celaya Dept Mech Engn Celaya Gto 38010 Mexico

ISBN: (纸本)9781467365376

In this paper, we presented a Path Planning Algorithm ( PPA) for Manipulators based on an improved Backtracking Search Algorithm ( BSA). PPA calculates paths by searching grid points in Euclidean space directly instead of Configuration space( C-space). PPA generate copies of point for efficient Path Planning Algorithm and its reduce the complexity of BSA. The algorithm is back track free and resolution complete. Different from existing resolution complete algorithms, its computation time and memory space are proportional to the number of arms. Therefore paths can be calculated within practical time without backtrack even for manipulators with many arms, and it becomes possible to apply it to manipulators that operate in complicated and fully automated environments. The performance of PPA is evaluated for 2-dimensional environments while changing the number of arms and obstacle placements.

关键词： Path Planning Manipulator Backtrack Euclidean Spac computation time

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Scalability of QP solvers for Embedded Model Predictive Control Applied to a Subsea Petroleum Production System

Scalability of QP solvers for Embedded Model Predictive Cont...

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IEEE Conference on Control and Applications (CCA)

作者： Binder, B. J. T. Kufoalor, D. K. M. Johansen, T. A. Norwegian Univ Sci & Technol Dept Engn Cybernet OS Bragstads Plass 2D NO-7491 Trondheim Norway NTNU Ctr Autonomous Marine Operat & Syst Trondheim Norway

ISBN: (纸本)9781479977871

The performance of two different Quadratic Programming (QP) solvers for embedded Model Predictive Control (MPC), FiOrdOs and qpOASES, is evaluated for a relevant case study from the petroleum industry. Embedded MPC for the considered system is implemented on a PLC (Programmable Logic Controller) using both solvers. The focus is on the computation time and memory requirements of the solvers as the dimensions of the control problem increase. The results show that qpOASES has a superior performance for small systems with respect to computation time. However, qpOASES has a near cubic growth in computation time with respect to the number of system variables, while FiOrdOs only has a near linear growth. FiOrdOs may thus be faster for larger systems. FiOrdOs has a smaller memory footprint than qpOASES for small systems;however, the program size grows faster than with qpOASES, and for the largest system configuration, the program sizes were almost identical. For even larger systems, qpOASES may have smaller program memory requirements than FiOrdOs, though qpOASES requires more data memory for all problem sizes.

关键词： embedded systems petroleum industry predictive control programmable controllers quadratic programming FiOrdOs PLC QP solvers computation time cubic growth data memory embedded MPC embedded model predictive control linear growth memory footprint program memory requirements program sizes programmable logic controller qpOASES subsea petroleum production system system configuration system variables Generators Inductors Manifolds Mathematical model Memory management Petroleum Programmable logic controllers Petroleum Industry quadratic programming computational time Data storage devices Predictive control Program size Store management inductors Solvers Manifolds Embedded systems Petroleum dynamos Mathematical Model

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Simple and accurate thermal simulation model of supercapacitor suitable for development of module solutions

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2014年 84卷 34-47页

作者： Frivaldsky, Michal Cuntala, Jozef Spanik, Pavol Univ Zilina Fac Elect Engn Dept Mechatron & Elect Zilina 01026 Slovakia

In this article, first the design procedure of the thermal model of a EDLC type wound capacitor (Electrochemical double layer capacitor) is described, whereby the main objective of modeling is achievement of a very close accordance of simulation results compared to measurements in various operating conditions. Development process is supported by the mathematical analysis of the internal structure of EDLC. Based on the requirements on high degree of model's accuracy, three alternatives of model's complexity are shown. Instead of accuracy the proper model has to fulfill also requirement on the computation time. Next, to meet further demands of complex modeling of supercapacitor modules, mentioned abilities (accuracy of simulation results and fast computation time of solution) must be as lowest as possible. The second important aim of this paper is the description of the development procedure of thermal simulation model of EDLC module (multi-cell supercapacitor system). Consequently simplifications targeting lowest simulation time with achievement of high model's accuracy are provided. At the end of the paper, reader is able to find simulation experiments which are confirming the proposed design procedure. (C) 2014 Elsevier Masson SAS. All rights reserved.

关键词： Supercapacitor Thermal simulation model computation time Complexity Optimization

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Block-Processing Soft-Input Soft-Output Demodulator for Coded PSK Using DCT-Based Phase Noise Estimation

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IEEE TRANSACTIONS ON COMMUNICATIONS 2014年第8期62卷 2939-2950页

作者： Noels, Nele Bhatti, Jabran Bruneel, Herwig Moeneclaey, Marc Univ Ghent Dept Telecommun & Informat Proc B-9000 Ghent Belgium

This paper considers the detection of coded phase-shift keying signals subjected to additive white Gaussian noise and oscillator phase noise. We propose a detector that partitions the received frame into smaller blocks and models the unknown phasor variations over each block as a truncated discrete cosine transform (DCT) expansion. Detection and decoding are iteratively performed between a soft-input soft-output (SISO) demodulator, a SISO demapper, and a SISO decoder based on the sum-product algorithm and the factor graph framework, whereas the expectation-maximization algorithm is used in the demodulator for the DCT coefficients estimation. The resulting demodulator is shown to have an excellent performance/complexity tradeoff and to be well-suited for parallel processing on multiple cores.

关键词： Phase noise synchronization parallel algorithms parameter estimation error correction coding computation time communication systems digital communication digital signal processors discrete cosine transforms

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