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Random feed errors in phased array antennas

WSEAS Transactions on Communications 2006年第8期5卷 1439-1446页

作者： Farsaris, Nikos J. Xenos, Thomas D. Electromagnetic Fields Measurements Applied Informatics and Multimedia Dept. A.T.E.I. of Crete Iraklion Crete Greece Telecommunications Department Electrical and Computer Engineering Faculty Aristotle University of Thessaloniki Thessaloniki Greece

In many cases accuracy of construction plays a significant role in antenna performance. In this paper an error analysis is studied, and it can be shown that tolerances can be accepted in some cases, making the antenna manufacturers business easier. The tolerances studied here, is random signal amplitude and random phase applied on antenna element feeds. A Gaussian distribution is considered most probable for amplitude errors while uniform and Gaussian distributions are examined for phase errors. Combined cases are examined also for both amplitude and phase errors. In the first part (Introduction) the characteristics of a phased array are briefly analyzed. In part 2 amplitude error analyses are given alongside simulation results. In part 3 and 4 the same is done for phase errors (Gaussian and uniform distribution). In parts 5 and 6 combined Gaussian-Uniform and Gaussian-Gaussian distributions for both amplitude and phase errors are given. In the conclusion (part 7) it is shown that there are certain limits where the antenna performance is acceptable, especially when military use is the designer's goal.

关键词： Antenna phased arrays

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Automatic registration of large set of microscopic images using high-level features

Automatic registration of large set of microscopic images us...

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IEEE International Symposium on Biomedical Imaging

作者： J. Prescott M. Clary G. Wiet T. Pan Kun Huang Department of Electrical and Computer Engineering Ohio State Uinversity Columbus OH USA Department of Otolaryngology Ohio State Uinversity Columbus OH USA Department of Biomedical Informatics Ohio State Uinversity Columbus OH USA

In this paper, we present a novel method for automatic registration of large set of microscopic images by automatically match high-level region features via finding cyclic structures in a matching graph. The use of high-level features (e.g., regions, landmarks, objects) significantly reduced the computation and provides accurate initialization, which further allows fast convergence of the maximum mutual information algorithm. The scheme is a universal one as it works for other types of high-level features and the matching process is very computationally efficient. We have applied our method in 3-D reconstruction of a unique human cochlear sample and are also applying it to two other set of large microscopic images

关键词： Microscopy Mutual information Biomedical informatics Three dimensional displays Visualization Convergence Humans Ear computer vision NP-complete problem

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An integrated temporal partitioning and physical design framework for real-time reconfigurable systems

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WSEAS Transactions on Circuits and Systems 2006年第2期5卷 248-255页

作者： Mehdipour, Farhad Zamani, Morteza Saheb Ahmadifar, Hamid. R. Sedighi, Mehdi Murakami, Kazuaki Computer and IT Engineering Department Amirkabir University of Technology # 424 Hafez Ave Tehran Iran Engineering Faculty Guilan University Engineerinf Faculty Rasht Iran Department of Informatics Graduate School of Information Science and Electrical Engineering Kyushu University 6-1 Kasuga-Koen Kasuga Fukuoka 816-8580 Japan

In a reconfigurable system, configurations are swapped in/out at run-time duration. The number of reconfigurations is an important factor to determine the overall run-time and reconfiguration overhead time is usually the dominant time factor. We have generated a framework for temporal partitioning and physical design of data flow graphs for a real-time environment. In this work, a temporal partitioning algorithm is presented which partitions data flow graphs in a real-time domain. Timing constraint is a critical factor in temporal partitioning of real-time reconfigurable design. We propose an incremental temporal partitioning algorithm for real-time reconfigurable applications. In this algorithm, the maximum number of partitions which is appropriate for running input data flow graph at the specified time is determined. Also, appropriate device size is determined with respect to the number of partitions. An iterative partitioning process tries to perform the partitioning to obtain desired the number of partitions after an initial partitioning. Also, a post processing algorithm attempts to minimize the required device size. In this algorithm, selecting the appropriate nodes and moving them between subsequent partitions results in more area balanced partitions and less number of partitions.

关键词： Real time systems

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Impact of Rapid Photothermal Processing on Properties of ZnO Nanostructures for Solar Cell Applications

Impact of Rapid Photothermal Processing on Properties of ZnO...

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International Conference on Microelectronics, MIEL

作者： S. Shishiyanu R. Singh T. Shishiyanu O. Lupan Department of Microelectronics and Semiconductor Devices Faculty of Computers Informatics and Microelectronics Technical University of Moldova Chisinau Moldova Center for Silicon Nanoelectronics Holcombe Department of Electrical and Computer Engineering Clemson University Clemson SC USA

The nanotechnology with chemical deposition (CD) and rapid photothermal processing (RPP) of nanostructured ZnO thin films for solar cell applications was elaborated. The influence of growth processes and the impact of RPP on surface morphology, particles size and resistivity values are presented and discussed. The ZnO thin films were deposited on silicon substrates by chemical deposition method at room temperature and normal pressure. The obtained thin films were rapid photothermal processed in vacuum and N 2 ambient. Nanostructures of the deposited films were optimized by adjusting various growth parameters: concentration of zinc complex solution, temperature of aqueous solution of anions and RPP regimes. Structural and electrical properties were investigated by energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), electrical resistivity measurements. electrical resistivity measurements showed that the room temperature resistivity of 10 5 Omega-cm for as-deposited ZnO, decreased to 10 3 Omega-cm after rapid photothermal processing. The impact of RPP temperatures was found to have an important role in the formation of ZnO nanostructures properties for solar cells applications and photoluminescence enhancement. The highest intensity of photoluminescence was obtained at 650degC RPP temperature. The experimental results shown that by RPP is possible to control the surface morphology, electrical properties and photoluminescence of nanostructured zinc oxide thin films as active component and antireflection coating of the solar cells

关键词： Zinc oxide Nanostructures Photovoltaic cells Temperature Photoluminescence Sputtering Surface morphology Conductivity Transistors Scanning electron microscopy

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The influence of MIMO terminal user's hand on channel capacity

The influence of MIMO terminal user's hand on channel capaci...

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European Conference on Antennas and Propagation, EuCAP

作者： T. Zervos A. Alexandridis K. Peppas F. Lazarakis K. Dangakis C. Soras B. Lindmark Department of Electrical & Computer Engineering University of Patras Patras Greece Institute of Informatics & Telecommunications National Centre for Scientific Research Athens Greece Department of Signals Sensors and Systems Royal Institute of Technology Stockholm Sweden

In this paper the impact of user's hand holding a multiple-input-multiple-output (MIMO) terminal on the system performance is investigated. A 4times4 MIMO system is considered with a personal digital assistant (PDA) terminal equipped with a compact array of 4 patch elements. The radiation patterns of the antenna elements are simulated in the presence of the other elements and in the presence of a user's hand. The obtained patterns are used to evaluate the covariance matrix of the receive antenna which is incorporated in a correlation-based MIMO channel model. MIMO channel capacity is calculated to demonstrate the capacity degradation caused by the user's hand.

关键词： MIMO Channel capacity Personal digital assistants Antenna radiation patterns Mobile antennas System performance Impedance Biological tissues Humans Frequency

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Efficient Channel Assignment technique providing priority to Emergency Calls in Wireless Cellular Security Networks

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WSEAS Transactions on Communications 2006年第1期5卷 84-91页

作者： Ioannou, K. Dimitriadou, E. Ioannou, A. Panoutsopoulos, I. Garmpis, A. Kotsopoulos, S. Wireless Telecommunication Laboratory Department of Electrical and Computer Engineering University of Patras Rion 26500 Patras Greece OTE S.A. Messolonghi 30200 Greece Department of Applied Informatics in Management and Economy Technological Educational Institution of Messolonghi Messolonghi 30200 Greece

In this paper is presented a new efficient Channel Assignment technique. The philosophy of this technique is that provides priority to Emergency Calls in Wireless Cellular Security Networks. The new technique is based on a two-layer cellular architecture The lower layer of the proposed architecture is based on a microcellular solution, for absorbing the traffic loads of both the handoff and new calls of Emergency Calls (EC). The higher layer is based on a macro-cell umbrella solution, for absorbing the traffic load of the handoff and new calls of the Non Emergency Calls (NEC). The simulation results show that using the optimum number of channels in each layer, the QoS of EC and the Handoff Blocking Probability of NEC in a congested area where an extreme event was happened is optimized, having the minimum negative effect on the New Call Blocking Probability of the NEC.

关键词： Wireless telecommunication systems

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ROBUST STABILITY CHECKING OF A CLASS OF LINEAR INTERVAL FRACTIONAL ORDER SYSTEM USING LYAPUNOV INEQUALITY

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IFAC Proceedings Volumes 2006年第11期39卷 89-94页

作者： Hyosung Ahn YangQuan Chen Igor Podlubny Center for Self-Organizing and Intelligent Systems (CSOIS) Department of Electrical and Computer Engineering Utah State University Logan UT 84322-4160 USA Department of Applied Informatics and Process Control Technical University of Kosice B. Nemcovej 3 04200 Kosice Slovak Republic

This paper provides a new analytical robust stability checking method of fractional-order linear time invariant interval uncertain system. This paper continues the authors’ previous work (Chen et al., 2005a) where matrix perturbation theory was used. For the new robust stability checking, Lyapunov inequality is utilized for finding the maximum eigenvalue of a Hermitian matrix. Through numerical examples, the usefulness and the effectiveness of the newly proposed method are verified.

关键词： Fractional order linear dynamic systems robust stability interval linear time invariant systems interval matrix

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Automated tracking and modeling of microtubule dynamics

Automated tracking and modeling of microtubule dynamics

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IEEE International Symposium on Biomedical Imaging

作者： M. Saban A. Altinok A. Peck C. Kenney S. Feinstein L. Wilson K. Rose B.S. Manjunath Center for Bio-image Informatics Department of Electrical and Computer Engineering University of California슠Santa Barbara Santa Barbara CA USA Center for Bio-image Informatics Department of Computer Science University of California슠Santa Barbara Santa Barbara CA USA Center for Bio-image Informatics Department of Molecular Cellular and Developmental Biology University of California슠Santa Barbara Santa Barbara CA USA

The method of microtubule tracking and dynamics analysis, presented here, improves upon the current means of manual and automated quantification of microtubule behavior. Key contributions are increasing accuracy and data volume, eliminating user bias and providing advanced analysis tools for the discovery of temporal patterns in cellular processes. By tracking the entire length of each resolvable microtubule, as opposed to only the tip, it is possible to boost dynamics studies with positional information that is virtually impossible to collect manually. We demonstrate the method on the analysis of a microtubule dataset, which was manually tracked and analyzed in the study of betaIII-tubulin isoform. Our results show that automated recognition of temporal patterns in cellular processes offers a highly promising potential

关键词： Biological system modeling Cells (biology) Microscopy informatics Biology computing Proteins Videos Fluorescence Machine learning Interference constraints

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Average Row Thresholding Method for Mammogram Segmentation

Average Row Thresholding Method for Mammogram Segmentation

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： A.A. AbuBaker R.S. Qahwaji M.J. Aqel M.H. Saleh School of Informatics University of Bradford Bradford West Yorkshire UK EMIC school of Informatics University of Bradford Bradford West Yorkshire UK University of Bradford Bradford West Yorkshire UK Electrical and Computer Engineering Department University of Applied Science University Jordan

Two novel threshold techniques are proposed for image segmentation which is a very critical task in any image processing. The two methods are based in scanning each image row by row and to find the proper threshold value. A modification of this method is developed to find the threshold value by average. The two methods are implemented on a mammogram and accordingly, a comparison between the two methods is carried out

关键词： Image segmentation Entropy Histograms Image processing Image edge detection informatics Digital images Image analysis Neural networks Fuzzy neural networks

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Variable Forgetting Factor-Based Friction Compensation Method of Precision Stages

Variable Forgetting Factor-Based Friction Compensation Metho...

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SICE Annual Conference

作者： Shigeki Goka Seiji Hashimoto Kiyoshi Ohishi Takeo Ishikawa Shuichi Adachi Koji Kosaka Hiroshi Kubota Tadahiro Ohmi Department of Electronic Engineering Gunma University Gunma Japan Department of Electrical Engineering Nagaoka University of Technology Niigata Japan Department of Applied Physics and Physico-Informatics Keio University Kanagawa Japan Tech Concierge Kumamoto Kumamoto Japan Department of Electrical and Computer Engineering Kumamoto University Kumamoto Japan Future Information Industry Creation Center University of Tohoku Miyagi Japan

This paper presents the nonresonant ultrasonic motor (SPIDER)-driven precision stage control based on an adaptive identification method with a variable forgetting factor (VFF). SPIDER-driven stage has a strong non-linearity due to the frictional drive mechanism. Focusing on the VFF, dynamical change of frictional property is detected. Therefore, fast and precise friction compensation can be performed based on the VFF. The validity of both the identification and compensation methods is verified through experiments

关键词： Friction Leg Electronics industry Actuators Position measurement Industrial electronics Physics computing computer industry Industrial control Electric variables control

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