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Dubhe: A Reliable and Low-Latency Data Dissemination Mechanism for VANETs

INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS 2013年第unknown期2013卷 1-16页

作者： Zhang, Lifeng Jin, Beihong Chinese Acad Sci Inst Software Beijing 100190 Peoples R China Univ Chinese Acad Sci Beijing 100190 Peoples R China

Many attractive applications over vehicular ad hoc networks (VANETs) need data to be transmitted to the remote destinations through multihop data forwarding, but some unique characteristics of VANETs (i.e., high node mobility, dynamic topology changes with frequent link breakage, and unstable quality of wireless transmission) incur unstable data delivery performance. In order to reliably and quickly disseminate the data, we present Dubhe which includes a delay model and an improved greedy broadcast algorithm embedded with a coverage elimination rule. The former is used for making decisions for path selection with the aim of minimizing the transmission latency, while the latter focuses on boosting the reliability of one-hop data transmission. We also analyze the necessity and effectiveness of Dubhe and the retransmission overheads theoretically. It is shown from the experiments that Dubhe can achieve high-reliability and low-latency data delivery in comparison with the epidemic-based protocol and the static-node-assisted adaptive data delivery protocol.

关键词： VEHICULAR ad hoc networks (computer networks) DATA transmission systems BROADCAST data systems GREEDY algorithms computer algorithms WIRELESS communication systems

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Algorithm-based modelling of fractional ion abundance and rates of ionization and recombination for tungsten plasmas

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JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS 2013年第17期46卷 175701-175701页

作者： Sasaki, A. Murakami, I. Japan Atom Energy Agcy Quantum Beam Sci Directorate Kizugawa Kyoto 6190215 Japan Natl Inst Nat Sci Natl Inst Fus Sci Toki Gifu 5095292 Japan

The fractional ion abundance and rates of ionization and recombination of multiple charged tungsten ions in magnetic fusion plasmas are investigated using a collisional radiative model. Using a computer algorithm to generate a set of atomic states to be included in the collisional radiative model, the dominant dielectronic recombination and excitation autoionization channels are determined by a systematic convergence analysis of the level population and ion abundance with respect to the size of the model. The atomic data, such as energy levels and rates of the radiative decay as well as autoionization, are obtained by the ab initio calculation using the Hebrew University Lawrence Livermore Atomic Code. The calculations are carried out in the temperature range of 100 eV-5 keV, and the ratio between the abundances of W44+ and W45+ ions agrees well with an experimental result obtained without any artificial adjustment of the atomic rates.

关键词： TUNGSTEN ions IONIZATION (Atomic physics) RESEARCH SCIENTIFIC models computer algorithms ION recombination AUGER effect

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Range-Free Localization Scheme in Wireless Sensor Networks Based on Bilateration

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INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS 2013年第1期2013卷 1-10页

作者： Chen, Chi-Chang Chang, Chi-Yu Li, Yan-Nong I Shou Univ Dept Informat Engn Kaohsiung 84001 Taiwan

A low-cost yet effective localization scheme for wireless sensor networks (WSNs) is presented in this study.. e proposed scheme uses only two anchor nodes and uses bilateration to estimate the coordinates of unknown nodes. Many localization algorithms for WSNs require the installation of extra components, such as a GPS, ultrasonic transceiver, and unidirectional antenna, to sensors.. e proposed localization scheme is range-free (i.e., not demanding any extra devices for the sensors). In this scheme, two anchor nodes are installed at the bottom-le. corner (Sink X) and the bottom-right corner (Sink Y) of a square monitored region of the WSN. Sensors are identified with the same minimum hop counts pair to Sink X and Sink Y to form a zone, and the estimated location of each unknown sensor is adjusted according to its relative position in the zone.. is study compares the proposed scheme with the well-known DV-Hop method. Simulation results show that the proposed scheme outperforms the DV-Hop method in localization accuracy, communication cost, and computational complexity.

关键词： WIRELESS sensor networks GLOBAL Positioning System TELECOMMUNICATION computer algorithms computer science

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Energy Balanced Scheduling for Target Tracking with Distance-Dependent Measurement Noise in a WSN

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INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS 2013年第unknown期2013卷 1-12页

作者： Hu, Xiaoqing Bao, Ming Hu, Yu-Hen Xu, Bugong Chinese Acad Sci Inst Acoust Key Lab Noise & Vibrat Res Beijing 100190 Peoples R China S China Univ Technol Coll Automat Sci & Engn Guangzhou 510640 Guangdong Peoples R China Univ Wisconsin Dept Elect & Comp Engn Madison WI 53706 USA

Energy efficient collaborative target tracking in a wireless sensor network (WSN) is considered. It is assumed that the distance estimates of range sensors are contaminated by distance-dependent multiplicative observation noises. The nonlinear measurement model leads to the application of a generalized unscented Kalman filtering (GUKF) tracking algorithm. Energy efficient operation is achieved by imposing an energy balance criterion to select a subset of sensors near the target to participate in collaborative tracking without compromising tracking performance. This is formulated as a multiobjective constrained optimization problem that minimizes both the state covariance of the GUKF algorithm and the variance of on-board residue energy of sensor nodes within the detection range of the target. An efficient, distributed, polynomial time heuristic algorithm that achieves a performance close to the optimal solution is proposed. Extended simulation results indicate that this proposed joint scheduling and tracking algorithm is capable of delivering desired tracking performance while significantly extending theWSN lifespan.

关键词： WIRELESS sensor networks ENERGY consumption KALMAN filtering computer algorithms POLYNOMIAL time algorithms computer scheduling

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Ancestral Dynamic Voting Algorithm for Mutual Exclusion in Partitioned Distributed Systems

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INTERNATIONAL JOURNAL OF DISTRIBUTED SENSOR NETWORKS 2013年第11期9卷 1-15页

作者： Zarafshan, Faraneh Karimi, Abbas Al-Haddad, S. A. R. Saripan, M. Iqbal Subramaniam, Shamala Univ Putra Malaysia Fac Engn Dept Comp Syst Engn Serdang 43400 Selangor Malaysia Islamic Azad Univ Arak Branch Fac Engn Dept Comp Engn Arak 38453 Iran Univ Putra Malaysia Fac Comp Sci & IT Dept Commun Technol & Networks Serdang 43400 Selangor Malaysia

Data replication is a known redundancy used in fault-tolerant distributed system. However, it has the problem of mutual exclusion of replicated data. Mutual exclusion becomes difficult when a distributed system is partitioned into two or more isolated groups of sites. In this study, a new dynamic algorithm is presented as a solution for mutual exclusion in partitioned distributed systems. The correctness of the algorithm is proven, and simulation is utilized for availability analysis. Simulations show that the new algorithm, ancestral dynamic voting algorithm, improves the availability and lifetime of service in faulty environments, regardless of the number of sites and topology of the system. This algorithm also prolongs the lifetime of service to mutual exclusion for full and partial topologies especially for the situations where there is no majority. Furthermore, it needs less number of messages transmitted. Finally, it is simple and easy to implement.

关键词： computer algorithms computer programming DATA replication DATA warehousing computer simulation

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Optimization Controller for Mechatronic Sun Tracking System to Improve Performance

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ADVANCES IN MECHANICAL ENGINEERING 2013年第Pt.6期5卷 146352-1-146352-9页

作者： Engin, Mustafa Engin, Dilsad Ege Univ Ege Higher Vocat Sch Dept Elect Technol TR-35100 Izmir Turkey Ege Univ Ege Higher Vocat Sch Dept Control & Automat Technol TR-35100 Izmir Turkey

An embedded system that contains hardware and software was developed for two-axis solar tracking system to improve photovoltaic panel utilization. The hardware section of the embedded system consists of a 32-bit ARM core microcontroller, motor driver circuits, a motion control unit, pyranometer, GPS receiver, and an anemometer. The real-time control algorithm enables the solar tracker to operate automatically without external control as a stand-alone system, combining the advantages of the open-loop and the closed-loop control methods. The pyranometer is employed to continuously send radiation data to the controller if the measured radiation is above the lower radiation limit the photovoltaic panel can generate power, guaranteeing the solar tracking process to be highly efficient. The anemometer is utilized in the system to ensure that the solar tracking procedure halts under high wind speed conditions to protect the entire system. Latitude, longitude, altitude, date, and real-time clock data are provided by GPS receiver. The algorithm calculates solar time using astronomical equations with GPS data and converts it to pulse-width modulated motor control signal. The overall objective of this study is to develop a control algorithm that improves performance and reliability of the two-axis solar tracker, focusing on optimization of the controller board, drive hardware, and software.

关键词： computer software Stand-Alone System SOLAR TRACKING Embedded systems PULSE WIDTH Control Methods computer algorithms computer hardware Sun tracker Anemometers GPS Receiver Controllers wind speed pyranometers

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Recursive Neural Networks Based on PSO for Image Parsing

ABSTRACT AND APPLIED ANALYSIS

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ABSTRACT AND APPLIED ANALYSIS 2013年第Spe42期2013卷 1-7页

作者： Cai, Guo-Rong Chen, Shui-Li Jimei Univ Sch Sci Xiamen Peoples R China

This paper presents an image parsing algorithm which is based on Particle Swarm Optimization (PSO) and Recursive Neural Networks (RNNs). State-of-the-art method such as traditional RNN-based parsing strategy uses L-BFGS over the complete data for learning the parameters. However, this could cause problems due to the nondifferentiable objective function. In order to solve this problem, the PSO algorithm has been employed to tune the weights of RNN for minimizing the objective. Experimental results obtained on the Stanford background dataset show that our PSO-based training algorithm outperforms traditional RNN, Pixel CRF, region-based energy, simultaneous MRF, and superpixel MRF.

关键词： NEURAL networks (computer science) PARTICLE swarm optimization PARAMETER estimation NONDIFFERENTIABLE functions computer algorithms ARTIFICIAL intelligence

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Modeling vitreous silica bilayers

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Physical Review B 2013年第21期87卷 214108-214108页

作者： Mark Wilson Avishek Kumar David Sherrington M. F. Thorpe Univ Oxford Dept Chem Phys & Theoret Chem Lab Oxford OX1 3QZ England Arizona State Univ Dept Phys Tempe AZ 85287 USA Univ Oxford Rudolf Peierls Ctr Theoret Phys Oxford OX1 3NP England Santa Fe Inst Santa Fe NM 87501 USA

Theoretical modeling is presented for a freestanding vitreous silica bilayer which has recently been synthesized and characterized experimentally in landmark work. While such two-dimensional continuous random covalent networks should likely occur on energetic grounds, no synthetic pathway had been discovered previously. Here the bilayer is modeled using a computer assembly procedure initiated from a single layer of a model of amorphous graphene, generated using a bond-switching algorithm from an initially crystalline graphene structure. Each bond is decorated with an oxygen atom and the carbon atoms are relabeled as silicon, generating a two-dimensional network of corner-sharing triangles. Each triangle is transformed into a tetrahedron, by raising the silicon atom above each triangular base and adding an additional singly coordinated oxygen atom at the apex. The final step in this construction is to mirror-reflect this layer to form a second layer and attach the two layers to form the bilayer. We show that this vitreous silica bilayer has the additional macroscopic degrees of freedom to form easily a network of identical corner-sharing tetrahedra if there is a symmetry plane through the center of the bilayer going through the layer of oxygen ions that join the upper and lower monolayers. This has the consequence that the upper rings lie exactly above the lower rings, which are tilted in general. The assumption of a network of perfect corner-sharing tetrahedra leads to a range of possible densities that we characterize as a flexibility window, with some similarity to flexibility windows in three dimensional zeolites. Finally, using a realistic potential, we have relaxed the bilayer to determine the density and other structural characteristics such as the Si-Si pair distribution functions and the Si-O-Si bond angle distribution, which are compared with experimental results obtained by direct imaging.

关键词： SILICA COVALENT crystals computer algorithms CRYSTAL structure GRAPHENE

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An RBF Neural Network Combined with OLS Algorithm and Genetic Algorithm for Short-Term Wind Power Forecasting

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JOURNAL OF APPLIED MATHEMATICS 2013年第unknown期2013卷 1-9页

作者： Chang, Wen-Yeau St Johns Univ Dept Elect Engn New Taipei City 25135 Taiwan

An accurate forecasting method for power generation of the wind energy conversion system (WECS) is urgently needed under the relevant issues associated with the high penetration of wind power in the electricity system. This paper proposes a hybrid method that combines orthogonal least squares (OLS) algorithm and genetic algorithm (GA) to construct the radial basis function (RBF) neural network for short-term wind power forecasting. The RBF neural network is composed of three-layer structures, which contain the input, hidden, and output layers. The OLS algorithm is used to determine the optimal number of nodes in a hidden layer of RBF neural network. With an appropriate RBF neural network structure, the GA is then used to tune the parameters in the network, including the centers and widths of RBF and the connection weights in second stage. To demonstrate the effectiveness of the proposed method, the method is tested on the practical information of wind power generation of a WECS installed in Taichung coast of Taiwan. Comparisons of forecasting performance are made to the persistence method and back propagation neural network. The good agreements between the realistic values and forecasting values are obtained;the test results show the proposed forecasting method is accurate and reliable.

关键词： NEURAL networks (computer science) LEAST squares computer algorithms RADIAL basis functions GENETIC algorithms

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Real-Time Energy Management Control for Hybrid Electric Powertrains

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JOURNAL OF CONTROL SCIENCE AND ENGINEERING 2013年第unknown期2013卷 801237.1-801237.10页

作者： Zaher, Mohamed Cetinkunt, Sabri Univ Illinois Chicago IL 60607 USA

This paper focuses on embedded control of a hybrid powertrain concepts for mobile vehicle applications. Optimal robust control approach is used to develop a real-time energy management strategy. The main idea is to store the normally wasted mechanical regenerative energy in energy storage devices for later usage. The regenerative energy recovery opportunity exists in any condition where the speed of motion is in the opposite direction to the applied force or torque. This is the case when the vehicle is braking, decelerating, the motion is driven by gravitational force, or load driven. There are three main concepts for energy storing devices in hybrid vehicles: electric, hydraulic, and mechanical (flywheel). The real-time control challenge is to balance the system power demands from the engine and the hybrid storage device, without depleting the energy storage device or stalling the engine in any work cycle. In the worst-case scenario, only the engine is used and the hybrid system is completely disabled. A rule-based control algorithmis developed and is tuned for different work cycles and could be linked to a gain scheduling algorithm. A gain scheduling algorithm identifies the cycle being performed by the work machine and its position via GPS and maps both of them to the gains.

关键词： Powertrain Engines Renewable energy Gravity HYBRID POWER Hybrid electric vehicles hybrid systems vehicle computer algorithms Torque Energy storage devices active force Gain Energy management opposite direction

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