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Microscopic analysis of Hopper flow with ellipsoidal particles

AIP Conference Proceedings 2013年第1期1542卷 694-697页

作者： Sida Liu Zongyan Zhou Ruiping Zou David Pinson Aibing Yu Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia Steelmaking Technology and Planning BlueScope Steel P.O. Box 202 Port Kembla NSW 2505 Australia

Hoppers are widely used in process industries. With such widespread application, difficulties in achieving desired operational behaviors have led to extensive experimental and mathematical studies in the past decades. Particularly, the discrete element method has become one of the most important simulation tools for design and analysis. So far, most studies are on spherical particles for computational convenience. In this work, ellipsoidal particles are used as they can represent a large variation of particle shapes. Hopper flow with ellipsoidal particles is presented highlighting the effect of particle shape on the microscopic properties.

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Discrete modelling of the packing of ellipsoidal particles

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AIP Conference Proceedings 2013年第1期1542卷 357-360页

作者： Zongyan Zhou Ruiping Zou David Pinson Aibing Yu Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia Steelmaking Technology and Planning BlueScope Steel P.O. Box 202 Port Kembla NSW 2505 Australia

Particle shape affects the packing characteristics significantly. Such a topic has been investigated extensively in the literature by physical experiments or mathematical modelling. In this paper, we give a summary of packing of ellipsoidal particles using discrete element method. As ellipsoidal particles can represent a large number of shapes, e.g. from platy to elongated, the relationships between packing properties (such as packing fraction, coordination number and radial distribution function) and aspect ratios are established. Flow and force structures are also presented to illustrate how the shape affects those microscopic properties for further fundamental understanding. The results demonstrate that discrete element method provides a useful method to investigate the packing dynamics of ellipsoidal particles.

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Impaction of particle streams on a granular bed

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AIP Conference Proceedings 2013年第1期1542卷 634-637页

作者： Sida Liu Zongyan Zhou Kejun Dong Aibing Yu John Tsalapatis David Pinson Laboratory for Simulation and Modelling of Particulate Systems School of Materials Science and Engineering The University of New South Wales Sydney NSW 2052 Australia OneSteel Whyalla SA 5600 Australia Steelmaking Technology and Planning BlueScope Steel P.O. Box 202 Port Kembla NSW 2505 Australia

Impaction of particle streams on granular beds can be observed in various processes. One typical example is the burden distribution in an ironmaking blast furnace. The stream of heavy iron-bearing pellets impacts the pre-formed coke surface at the blast furnace throat region. The coke layer then can move and collapse. The formed burden profile is important in controlling the radial distribution of gas flow, and hence productivity and stability. In this paper, the impaction of pellets on the coke surface is investigated using discrete element method. A 90 degree sector is modelled with a pre-formed coke surface impacted by pellets flowing from a rotating chute. Microscopic analysis on the flow and force structures is carried out to examine the impaction with different chute angles and discharge rates.

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Early Warning and Prevention of Potential Wide-Area Voltage Instability Problem

Early Warning and Prevention of Potential Wide-Area Voltage ...

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International Conference on Environment and Electrical engineering

作者： H. H. Goh Q. S. Chua B. C. Kok K. C. Goh S. W. Lee K. T. K. Teo Department of Electrical Power Engineering Faculty of Electrical and Electronic Engineering Universiti Tun Hussein Onn Malaysia Department of Construction Management Faculty of Technology Management and Business Universiti Tun Hussein Onn Modelling Simulation and Computing Laboratory Level 3 Block C School of Engineering and Information Technology Jalan UMS Universiti Malaysia Sabah

ISBN: (纸本)9781467330602

Nowadays, there is a must to operate the power system close to its security limit due to current economic growth and the difficulties to upgrade the existing grid infrastructure. With the sudden increment of demand, the voltage instability problem has become a main concern to the power system operator. Hence, methods for early warning of voltage instability are required to prevent the power system from a collapse. This paper describes the use of real-time voltage instability predictors for the load areas in the Tenaga Nasional Berhad (TNB) network based on measurement from Phasor Measurement Units (PMUs) placed at the boundary of the load center. The voltage instability predictor calculates the power margin and compares to the preset margin threshold. Finally, the stability of the system is based on the comparison between the margin and pre-set threshold.

关键词： Wide Area Measurement System (WAMS) Voltage Instability Predictor (VIP) Phasor Measurement Units (PMUs) Radial Equivalent Independent (REI) Network Kalman Filter

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Bright and peaklike pulse solitary waves and analogy with modulational instability in an extended nonlinear Schrödinger equation

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Physical Review E 2013年第4期88卷 043204-043204页

作者： Fabien Kenmogne David Yemélé Laboratory of Modelling and Simulation in Engineering and Biological Physics Faculty of Science University of Yaounde I P.O. Box 812 Yaounde Cameroon Laboratoire de Mécanique et de Modélisation des Systèmes Physiques L2MSP Faculté des Sciences Université de Dschang B.P. 067 Dschang Cameroon

The modulational instability (MI) phenomenon in the nonlinear Schrödinger equation (NLSE) extended by two different nonlinear dispersion terms and the gradient term is investigated. We find that the possibility of instability of plane waves depends on the sign of the nonlinear dispersion parameters with regard to the linear dispersion coefficient. In contrast to the basic NLSE, the system may exhibit instability in the defocusing media for amplitude exceeding a critical value depending on the magnitude of the nonlinear dispersion. An additional feature, namely the higher order or the infinite gain band, absent in the NLSE case, may appear and in which MI induces the birth of the nonlinear localized wave (NLW) of different carrier wave numbers. The result of the qualitative investigations of the system's dynamics indicates the existence of the NLW, such as peak, bright, dark, and compact dark solitary waves which can be well predicted by the MI criteria. In addition the nonlinear dispersion induces the existence of a pair of bright-dark solitary waves which is usually exhibited by the coupled NLSEs only, and the pairs of peak-dark and compact dark-bright solitary waves.

关键词： SOLITONS MODULATIONAL instability NONLINEAR Schrodinger equation PARTICLE size determination PARAMETERS (Statistics) LOCALIZED waves

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Cluster heads distribution of wireless sensor networks via adaptive particle swarm optimization

Cluster heads distribution of wireless sensor networks via a...

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2012 4th International Conference on Computational Intelligence, Communication Systems and Networks, CICSyN 2012

作者： Siew, Zhan Wei Wong, Chen How Chin, Chia Seet Kiring, Aroland Teo, Kenneth Tze Kin Modelling Simulation and Computing Laboratory School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu Malaysia

ISBN: (纸本)9780769548210

Wireless sensor networks consists of hundreds or thousands of sensor nodes supported by small capacity battery. For environmental monitoring purposes, sensor nodes must have high endurance capabilities. Therefore, selecting suitable cluster heads (CH) location becomes a challenging issue. In this work, cluster heads distribution based on adaptive particle swarm (PSO) is proposed. PSO is one of the swarm intelligence methods designed to find optimum solution by mimicking the behavior of bird flocking and fish schooling. Adaptive cognitive and social learning factor can achieve better convergence speed and particles reselection mechanism can reduce the chances of getting trapped in local maximum. The performance of the proposed method is compared with low energy adaptive cluster hierarchical (LEACH). simulation result shows that proposed method outperforms LEACH in terms of first node die (FND) round, total data received by base station and energy consume per round. © 2012 IEEE.

关键词： Sensor nodes

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Foetus ultrasound medical image segmentation via variational level set algorithm

Foetus ultrasound medical image segmentation via variational...

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3rd International Conference on Intelligent Systems modelling and simulation, ISMS 2012

作者： Choong, M.Y. Seng, M.C. Yang, S.S. Kiring, A. Teo, K.T.K. Modelling Simulation and Computing Laboratory School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu Malaysia

ISBN: (纸本)9780769546681

There is a challenge to segment the medical image which is often blurred and consists of noise. The objects to be segmented are always changing shape. Thus, there is a need to apply a method to automated segment well the objects for future analysis without any assumptions about the object's topology are made. In general, when performing pregnancy ultrasound scanning, obstetrician needs to find out the best position or angle of the foetus and freeze the scene. The obstetrician will click on the crown and the rump of the foetus to get the foetus length. The segmentation technique applied is level set method. A variational level set algorithm has been successfully implemented in medical image segmentation (Xray image, MRI image and ultrasound image). The results showed the level set contour evolved well on the low contrast and noise consisting medical image, especially the ultrasound image. © 2012 IEEE.

关键词： Image segmentation

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Performance analysis of utilizing coding nodes in wireless networks

Performance analysis of utilizing coding nodes in wireless n...

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2012 International Symposium on Telecommunication Technologies, ISTT 2012

作者： Tan, Shee Eng Siew, Zhan Wei Lye, Scott Carr Ken Yoong, Hou Pin Teo, Kenneth Tze Kin Modelling Simulation and Computing Laboratory School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu Malaysia

ISBN: (纸本)9781467347860

Network Coding is a method that effectively combines several packets from different sources and broadcasts the combined packet to several destinations in single transmission time slot. Each destination is capable to extract the intended information by decoding from a common packet. In short, network coding is a method that improves the throughput for wireless networks and wired networks. However, while it increases the throughput of networks, it also causes side effects such as complexity of packets management and increased delay for coding opportunity. In this paper, genetic algorithm is proposed to optimize the resources for network coding. Genetic algorithm will search for suitable routes to the destination according to the desired throughput with a desired multicast rate. The simulation results show that the average end to end delay of network after minimizing coding nodes is less than normal network coding. © 2012 IEEE.

关键词： Genetic algorithms

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Queue management for network coding in ad hoc networks

Queue management for network coding in ad hoc networks

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3rd International Conference on Intelligent Systems modelling and simulation, ISMS 2012

作者： Tan, S.E. Yew, H.T. Arifianto, M.S. Saad, I. Teo, K.T.K. Modelling Simulation and Computing Laboratory School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu Malaysia

ISBN: (纸本)9780769546681

Network Coding has been proven to be a method that will increase the throughput of network. Network coding will perform an XOR operation in the intermediate nodes to improve the throughput of the network. The simulation of network coding in AODV to search for the route to destination will be conducted in MATLAB. This paper introduces the development of simulation to illustrate the performance of network coding in wireless ad hoc network. The simulation will calculate the transmit packet time according to the size of the packet. Lastly, average network throughput performance between AODV network without network coding and network with network coding is shown and compared. © 2012 IEEE.

关键词： Network coding

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Multistage image clustering and segmentation with normalised cuts

Multistage image clustering and segmentation with normalised...

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3rd International Conference on Intelligent Systems modelling and simulation, ISMS 2012

作者： Choong, M.Y. Liau, C.F. Mountstephens, J. Arifianto, M.S. Teo, K.T.K. Modelling Simulation and Computing Laboratory School of Engineering and Information Technology Universiti Malaysia Sabah Kota Kinabalu Malaysia

ISBN: (纸本)9780769546681

Normalised cuts algorithm requires massive similarity measurement computation for image segmentation. Since a digital camera at present has the capability to produce high resolution image, it will be inevitably that resizing image into suitable resolution at which the algorithm can perform image segmentation with minimal burden. While retaining the important features in the images, natural images are likely to be restricted for resizing them into a particular smaller resolution. Dividing an image into equal size of regions (named as image cells) for the segmentation is proposed here to solve the problem of missing important features when the image resolution is overly reduced. Gradually, the locally segmented clusters from the image cells are taken for second stage segmentation to merge them up globally. In this paper, experimental results using the mentioned method are shown. Experiment shows that it is capable to produce reasonable segmented clusters based on the proposed approach. © 2012 IEEE.

关键词： Image segmentation

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