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International Conference on Mechatronics Engineering and Computing Technology (ICMECT)

作者： Zhang, Zhigang Yin, Li Li, Ting Naval Univ Engn Coll Elect Engn Wuhan 430033 Peoples R China PLA Unit 91336 Qinhuangdao 066000 Peoples R China

ISBN: (纸本)9783038351153

This paper analyzes the radiation characteristics of fishbone antenna arrays and concludes its optimum set of array formation. In order to study the feasibility of apply fishbone antenna into pashed array, the common fishbone antenna array is analyzed and simulated by the method of moments. It mainly calculated the radiation properties of two-element array, four-element array and six-element array under the linear array, rectangular array and sector array respectively. Comparing characteristics of different number of array element under the same array type and the different array types under the same number of array element, it suggests that two-element array is the most appropriate array type when sector arrayed, and the array types of 3 x 2, 2 x 2 and 1 x 2 have relatively good effect of beam scanning in low frequency with phase shift.

关键词： Fishbone antenna moment method parallel array sector array rectangular array

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On storing ragged arrays by hashing

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Mathematical Systems Theory 1976年第1期10卷 193-210页

作者： Rosenberg, Arnold L. Mathematical Sciences Department IBM Thomas J. Watson Research Center Yorktown Heights 10598 New York United States

The inevitably poor utilization of storage by computed-access realizations of extendible rectangular arrays can be circumvented by storing such arrays by hashing. This paper studies the extent to which the same switch in storage strategy avoids the even worse utilization of storage by computed-access realizations of extendible ragged (i.e., nonrectangular) arrays. Unfortunately, the dramatic successes of the rectangular case do not carry over: any hashing scheme for extendible ragged arrays with storage demands very much smaller than those of computed-access realizations must suffer expected access time that is close to worst possible. On the other hand, one can obtain moderate savings in storage demands by hashing ragged arrays, together with sufferable access time. This last result issues from a general technique for trading increased access time for savings in storage. Even more striking savings are attainable if one restricts attention to fully-justified ragged arrays, whose raggedness is more regular than that of general ragged arrays. However, the overall impact of our results is that extendible ragged arrays do not succumb to the storage strategies that work efficiently on their rectangular counterparts. © 1977 Springer-Verlag New York Inc.

关键词： Computational Mathematic General Technique Access Time Storage Strategy rectangular array

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Location of Partial Discharges Sources Using Sensor arrays 4

Location of Partial Discharges Sources Using Sensor Arrays

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International Conference on High Voltage Engineering and Application (ICHVE)

作者： Polak, F. Sikorski, W. Siodla, K. Poznan Univ Tech Inst Elect Power Engn Piotrowo 3A PL-60965 Poznan Poland

ISBN: (纸本)9781479966134

Occurrence of partial discharges (PD) is one of the basic criteria of high voltage devices insulation evaluation. Precise PD source location is crucial for undertaking maintenance of mentioned equipment. This paper concerns the issue of partial discharges sources location using phased rectangular arrays technique and high-resolution direction of arrival estimation technology. In addition to the theoretical assumptions of both techniques, the simulation result, in which an Uniform rectangular array (URA) was used for registration of the electromagnetic signals generated by defects in power transformer insulation system, were shown. To estimate the Direction of Arrival (DOA) of electromagnetic signals, that propagate from the discharge-generating defect to the transducer array installed on transformer tank, Minimum Variance Distortionless Response (MVDR) algorithm was chosen. The location of defect was determined using two intersecting lines defined by the DOAs from two URAs. With the ability to locate multisource discharges (even at very low signal to noise ratio - SNR), the adopted solution has advantages over conventional techniques.

关键词： direction-of-arrival estimation partial discharges power transformer insulation sensor arrays transducers DOA MVDR algorithm URA defect location determination direction of arrival estimation technology discharge generating defect electromagnetic signal registration high voltage device insulation evaluation intersecting lines minimum variance distortionless response multisource discharge location partial discharge source location phased rectangular arrays technique power transformer insulation system transducer array transformer tank uniform rectangular array Direction-of-arrival estimation Insulation Noise Partial discharges Power transformers Sensor arrays Sensor arrays Partial discharges Direction of arrival estimation transformer insulation transformer oil tanks United States Department of Agriculture low SNR ELECTRIC TRANSFORMERS Insulation Transducers rectangular array intersecting line Noise

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Decoupled 2D Direction Finding Based on Sparse Signal Reconstruction 33

Decoupled 2D Direction Finding Based on Sparse Signal Recons...

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33rd Annual IEEE Military Communications Conference on Affordable Mission Success - Meeting the Challenge (MILCOM)

作者： Wang, Feng Cui, Xiaowei Lu, Mingquan Tsinghua Univ Dept Elect Engn Beijing 100084 Peoples R China

ISBN: (纸本)9781479967704

A new two-dimensional direction finding algorithm called 2D-11-SVD is proposed in this paper. It is designed for rectangular arrays and can also be extended to rectangular arrays with faulty or missing elements. The key idea is to represent direction-of-arrival with two decoupled angles and then successively estimate them. Therefore two dimensional direction finding can be realized by applying several times of one dimensional sparse reconstruction based direction finding methods instead of directly extending them to two dimensional situation. Performance analysis and simulation results reveal that the proposed method has a much lower computational complexity and a similar performance compared with the wellknown 11-SVD algorithm, which has several advantages over conventional direction finding techniques due to the application of sparse signal reconstruction.

关键词： Direction-of-arrival estimation sparse signal reconstruction rectangular array faulty array

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Why sin 80x looks like sin x on some graphing calculators

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INTERNATIONAL JOURNAL OF MATHEMATICAL EDUCATION IN SCIENCE AND TECHNOLOGY 2005年第4期36卷 437-441页

作者： Zeng, J. Osler, T. J. Rowan Univ Math Dept Glassboro NJ 08028 USA

In rare cases, the use of advanced mathematical calculators can give incorrect results. One such error occurs with graphing calculators because the screen is not continuous, but a rectangular array of pixels. On some ... 详细信息

关键词： pixel rectangular array sin(-x) sin Calculators

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Vector Vortex Beam Transmitarrays Composed of Split-ring Slot Elements

Vector Vortex Beam Transmitarrays Composed of Split-ring Slo...

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USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) Proceedings

作者： Guclu, Caner Veysi, Mehdi Capolino, Filippo Univ Calif Irvine Dept Elect Engn & Comp Sci Irvine CA 92695 USA

ISBN: (纸本)9781479978175

A novel birefringent transmitarray capable of local polarization conversion in infrared regime is presented. In particular an incident beam with linear polarization can be transformed into a radially or azimuthally polarized vector beam and in general a wide continuum of polarization states are realizable on the higher order Poincare spheres. The transmitarray is composed of a rectangular array of double-layer double split-ring slot nanoantennas. The double layer element, chosen here, enables high transmission coefficient amplitude, thus increases the efficiency of conversion to the vector vortex beams. The array element exhibits anisotropy with respect to the field polarization on the transmitarray plane, where the transmission coefficients for two orthogonal linear polarizations are almost equal in magnitude and have almost a 180¡ã phase difference. This transmission condition is crucial in the geometric phase control method employed here and it is satisfied in a certain frequency band. The local polarization transformation on the array is controlled through manipulating the angular orientation of the slot elements with respect to element centers. Locally the phase of circularly polarized transmitted waves are advanced or delayed with a phase equal to twice the rotation angle. This phase control method is purely geometrical and it is not frequency dependent. For a certain transmitarray, the generated beam's polarization map is also a function of incident beam polarization. We then study the interesting case of azimuthally E-polarized vortex beams which are a superposition of the Laguerre Gaussian (LG) beams carrying certain orbital angular momentum (OAM) states. Such beams have a strong longitudinally polarized magnetic field on the propagation axis of the beam where the total electric field vanishes. We demonstrate analytically and through numerical field calculations, the evolution of electric and magnetic fields as the beam propagates. These finding are- partic

关键词： Beams and girders Polarization BEAM Control Methods vortices array Element magnetic field angular orientation Elements rectangular array incident beam phase difference

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Longitudinal Permeability of Spatially Periodic rectangular arrays of Circular Cylinders I. A Single Cylinder in the Unit Cell

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ZAMM - Journal of Applied Mathematics and Mechanics / Zeitschrift für Angewandte Mathematik und Mechanik 2002年第5期82卷

作者： V. Mityushev Prof. P.M. Adler Prof. Department of Mathematics Pedagogical University ul. Arciszewskiego 22b PL-76200 Slupsk Poland IPGP tour 24 4 place Jussieu F-75252 Paris Cedex 05 France

We study the longitudinal permeability of a spatially periodic rectangular array of circular cylinders, when a Newtonian fluid is flowing at low Reynolds number along the cylinders. The longitudinal component of the velocity obeys a Poisson equation which is transformed into a functional equation. This equation can be solved by the method of successive approximations. The major advantage of this technique is that the permeability of the array can be expressed analytically in terms of the radius of the cylinders and of the aspect ratio of the unit cell.

关键词： functional equation rectangular array effective permeability

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Optimal Stopping Times for Estimating Bernoulli Parameters with Applications to Active Imaging

Optimal Stopping Times for Estimating Bernoulli Parameters w...

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IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Safa C. Medin John Murray-Bruce Vivek K Goyal Boston University Electrical and Computer Engineering Department

ISBN: (纸本)9781538646595

We address the problem of estimating the parameter of a Bernoulli process. This arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. We introduce a framework within which to minimize the mean-squared error (MSE) subject to an upper bound on the mean number of trials. This optimization has several simple and intuitive properties when the Bernoulli parameter has a beta prior. In addition, by exploiting typical spatial correlation using total variation regularization, we extend the developed framework to a rectangular array of Bernoulli processes representing the pixels in a natural scene. In simulations inspired by realistic active imaging scenarios, we demonstrate a 4.26 dB reduction in MSE due to the adaptive acquisition, as an average over many independent experiments and invariant to a factor of 3.4 variation in trial budget.

关键词： adaptive sensing Bernoulli processes beta distribution computational imaging conjugate prior low-light imaging photon counting total variation regularization Conjugate prior Beta distribution photon counting Mean square error active imaging Bernoulli Bernoulli Trials stopping rectangular array

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DESIGN OF A rectangular FREQUENCY INVARIANT BEAMFORMER WITH A FULL AZIMUTH ANGLE COVERAGE

DESIGN OF A RECTANGULAR FREQUENCY INVARIANT BEAMFORMER WITH ...

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European signal processing conference

作者： Wei Liu Communications Research Group Department of Electronic and Electrical Engineering University of Sheffield Sheffield UK

ISBN: (纸本)9781617388767

A novel design of the frequency invariant beamformer based on a rectangular array is proposed. There are two unique features about this design: there is no taped delay-line (TDL) or any other temporal processing involved and the resultant beamformer has a full 360° azimuth angle coverage. Two design examples are provided with a satisfactory frequency invariant property.

关键词： broadband arrays frequency invariant beam-former rectangular arrays tapped delay-lines rectangular array azimuth Coverage Angle Azimuthal angle Invariant

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