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A Study on Group Key Agreement in Sensor Network Environments Using two-dimensional arrays

SENSORS 2011年第9期11卷 8227-8240页

作者： Jang, Seung-Jae Lee, Young-Gu Lee, Kwang-Hyung Kim, Tai-Hoon Jun, Moon-Seog Soongsil Univ Dept Comp Sci Seoul 156743 South Korea Seoil Univ Dept Internet Informat Seoul 131702 South Korea Hannam Univ Dept Multimedia Taejon 306791 South Korea

These days, with the emergence of the concept of ubiquitous computing, sensor networks that collect, analyze and process all the information through the sensors have become of huge interest. However, sensor network technology fundamentally has wireless communication infrastructure as its foundation and thus has security weakness and limitations such as low computing capacity, power supply limitations and price. In this paper, and considering the characteristics of the sensor network environment, we propose a group key agreement method using a keyset pre-distribution of two-dimension arrays that should minimize the exposure of key and personal information. The key collision problems are resolved by utilizing a polygonal shape's center of gravity. The method shows that calculating a polygonal shape's center of gravity only requires a very small amount of calculations from the users. The simple calculation not only increases the group key generation efficiency, but also enhances the sense of security by protecting information between nodes.

关键词： sensor network group key agreement two-dimensional array key pre-distribution quorum system

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One- and two-dimensional arrays of magnetic nanoparticles by the Langmuir-Blodgett technique

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ADVANCED MATERIALS 1999年第5期11卷 388-392页

作者： Iakovenko, SA Trifonov, AS Giersig, M Mamedov, A Nagesha, DK Hanin, VV Soldatov, EC Kotov, NA Oklahoma State Univ Dept Chem Stillwater OK 74078 USA Moscow State Univ Dept Phys Moscow 119964 Russia Hahn Meitner Inst Kernforsch Berlin GmbH Phys Chem Abt D-14109 Berlin Germany

Well‐ordered arrays of Fe 3 O 4 nanoparticles with a new type of packing have been produced using the Langmuir–Blodgett technique. Depending on the local absorption conditions, both 2D and 1D assemblies of nanoparticles are produced, the latter in the form of single and double chains of equally spaced nanoparticles. The Figure depicts a film of Fe 3 O 4 nanoparticles on a stearic acid monolayer.

关键词： Chemical beam epitaxy Quantum dots Giant magnetoresistance 2-dimensional electrons Force microscopy Thin-films Particles Size Nanocrystallites Monoparticulate Nanocrystals Giant magnetoresistance two-dimensional array Force Microscopies Quantum dots Chemical beam epitaxy thin films Magnetic nanoparticles

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FABRICATION AND CHARACTERIZATION OF TRANSDUCER ELEMENTS IN 2-dimensional arrayS FOR MEDICAL ULTRASOUND IMAGING

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 1992年第4期39卷 464-475页

作者： TURNBULL, DH FOSTER, FS UNIV TORONTO DEPT MED BIOPHYSTORONTO M4N 3M5ONTARIOCANADA UNIV TORONTO SUNNYBROOK HLTH SCI CTRDEPT MED BIOPHYSTORONTO M5S 1A1ONTARIOCANADA SUNNYBROOK HLTH SCI CTR TORONTOONTARIOCANADA

Some of the problems of developing a two-dimensional (2-D) transducer array for medical imaging are examined. The fabrication of a 2-D array material consisting of lead zirconate titanate (PZT) elements separated by epoxy is discussed. Ultrasound pulses and transmitted radiation patterns from individual elements in the arrays are measured. A diffraction theory for the continuous wave (CW) pressure field of a 2-D array element is generalized to include both electrical and acoustical cross-coupling between elements. This theory can be fit to model the measured radiation patterns of 2-D array elements, giving an indication of the level of cross-coupling in the array, and the velocity of the acoustic cross-coupling wave. Improvements in bandwidth and cross-coupling resulting from the inclusion of a front acoustic matching layer are demonstrated, and the effects of including a lossy backing material on the array are discussed. A broadband electrical matching network is described, and pulse-echo waveforms and insertion loss from a 2-D array element are measured.

关键词： fabrication Diffraction theory cross coupling Ultrasonography Radiation patterns insertion loss two-dimensional array Electricity Medical imaging array Element Cross-coupling reaction arrays

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Fabrication of ordered two-dimensional arrays of micro- and nanoparticles using patterned self-assembled monolayers as templates

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ADVANCED MATERIALS 1999年第17期11卷 1433-1437页

作者： Qin, D Xia, YN Xu, B Yang, H Zhu, C Whitesides, GM Harvard Univ Dept Chem & Biol Chem Cambridge MA 02138 USA Univ Washington Ctr Nanotechnol Seattle WA 98195 USA Univ Washington Dept Chem Seattle WA 98195 USA

A new method for the fabrication of ordered arrays of small particles is reported here. A combination of microcontact printing of SAMs, surface‐templated self‐assembly, and confined crystallization has been used to produce 2D arrays of micro‐ and nanoparticles. The method allows highly accurate control over size distribution and spatial arrangement for a broad range of substrates, such as CdS on Au, as shown in the Figure.

关键词： Quantum-dot arrays Particulate films Semiconductor Chemistry Particles Clusters Molecules State Gold Nanoparticles fabrication molecules Ordered two-dimensional array Countries (nations) Clusters self-assembled monolayers jigs(templates) Semiconductor materials

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Kronecker Product of two-dimensional arrays

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Acta Mathematicae Applicatae Sinica 2006年第1期22卷 1-8页

作者： Lei Hu State Key Laboratory of Iuformation Security Graduate School of Chinese Academy of Sciences Beijing 100049China

Kronecker sequences constructed from short sequences are good sequences for spread spectrum communication systems. In this paper we study a similar problem for two-dimensional arrays, and we determine the linear complexity of the Kronecker product of two arrays, Our result shows that similar good property on linear complexity holds for Kronecker product of arrays.

关键词： two-dimensional array Kronecker product linear complexity

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array decompositions for nonuniform computational environments

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JOURNAL OF PARALLEL AND DISTRIBUTED COMPUTING 1996年第2期36卷 91-105页

作者： Kaddoura, M Ranka, S Wang, A 4-116 Center for Science and Technology School of Computer and Information Science Syracuse University Syracuse New York 13244-4100

two-dimensional arrays are useful in a large variety of scientific and engineering applications. Parallelization of these applications requires the decomposition of array elements among different machines. Several data-decomposition techniques have been studied in the literature for machines with uniform computational power. In this paper, we develop new methods for decomposing arrays into a cluster of machines with nonuniform computational power. Simulation results show that our methods provide superior decomposition over naive schemes. (C) 1996 Academic Press Inc.

关键词： two-dimensional array new methods array Element machinery computational power machine Clusters

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Fluxoid Pinning in Superconductors by a Periodic array of Magnetic Particles

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JOURNAL OF LOW TEMPERATURE PHYSICS 1972年第3-4期9卷 241-253页

作者： Autler, S. H. Univ Lausanne Inst Phys Expt CH-1015 Lausanne Switzerland

We assume a two-dimensional array of ferromagnetic particles on the surface of a thin type-II superconductor in a transverse magnetic field. With a particle at the center of each fluxoid, the pinning force P and critical current increase Delta J(c) due to the particles are calculated. General expressions without arbitrary parameters are given for P and Delta J(c) as functions of magnetic field strength and the characteristics of the superconductor and the particles. For broad ranges of conditions values of P and Delta J(c) greater than 10(-7) dyn and 10(5) A/cm(2) result and for certain physically realistic sets of conditions, P > 10(-6) dyn and Delta J(c) > 10(6) A/cm(2) are predicted. The above effects should be readily observable. An experiment for setting up the assumed conditions is proposed and discussed in some detail.

关键词： field strength Magnetic flux type II superconductors Magnetic powders two-dimensional array Intramedullary Nailing particles Nailing transverse magnetic field Superconductors

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POLYNOMIAL SMOOTHING OF QUIET-TIME MAGNETIC VARIATIONS FOR AN IRREGULARLY SPACED array OF SITES

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PURE AND APPLIED GEOPHYSICS 1987年第1期125卷 41-65页

作者： ROSSEN, ML HERMANCE, JF Brown University

Both magnetospheric and solid Earth geophysicists often employ two-dimensional arrays of recording variometers to reconstruct the spatial distribution of transient magnetic field variations at the Earth's surface. These discrete data are typically interpolated over a dense grid and the results, for example, are contoured. Few studies, however, have explored the efficacy of employing various polynomial forms for interpolating the same data set, nor have they examined how regional polynomial forms relate to magnetic variation sources on a global scale. The present study addresses some of these concerns. We quantify the characteristics of various smoothed models (i.e., low-order polynomial trend surfaces) for the same data set from a subglobal network of magnetic variometers. Using a relatively quiet interval of undisturbed diurnal variation, we characterize the spatial distribution of the three individual magnetic vector components at a single instant of time—or for what we call a ‘time slice’. We then explore how our model functions are affected by the presence or absence of various site data, i.e., what is the ‘information content’ of a particular site in our array and how important is it to constraining the final smooth model function that we derive? Finally, we explore how such local model functions are affected by including data from outside the array by studying the relation between our local polynomial forms and the global source fields from which th

关键词： Dataset two-dimensional array Polynomial Thorium magnetic variations spatial distribution smoothing arrays

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Binary array set with zero correlation zone

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ELECTRONICS LETTERS 2001年第13期37卷 841-842页

作者： Tang, XH Fan, PZ Li, DB Suehiro, N SW Jiaotong Univ Inst Mobile Commun Chengdu 610031 Sichuan Peoples R China Beijing Univ Posts & Telecommun Dept Informat Engn Beijing 100088 Peoples R China Univ Tsukuba Grad Sch Syst & Informat Engn Tsukuba Ibaraki 305 Japan

The zero correlation zone (ZCZ) concept is extended from one-dimensional sequences to two-dimensional arrays. A class of binary arrays with ZCZ properties, based on two-dimensional mutually orthogonal complementary co... 详细信息

关键词： correlation theory set theory arrays two-dimensional array Combinatorial mathematics binary sequences one-dimensional sequence mutual orthogonality binary array set Codes two-dimensional complementary code zero correlation zone

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Adaptive Beamforming for array Imaging of Plate Structures Using Lamb Waves

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IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL 2010年第12期57卷 2712-2724页

作者： Engholm, Marcus Stepinski, Tadeusz Uppsala Univ Signals & Syst Grp Uppsala Sweden

Lamb waves are considered a promising tool for the monitoring of plate structures. Large areas of plate structures can be monitored using active arrays employing beamforming techniques. Dispersion and multiple propagating modes are issues that need to be addressed when working with Lamb waves. Previous work has mainly focused on standard delay-and-sum (DAS) beamforming while reducing the effects of multiple modes through frequency selectivity and transducer design. This paper presents a minimum variance distortionless response (MVDR) approach for Lamb waves using a uniform rectangular array (URA) and a single transmitter. Theoretically calculated dispersion curves are used to compensate for dispersion. The combination of the MVDR approach and the two-dimensional array improves the suppression of interfering Lamb modes. The proposed approach is evaluated on simulated and experimental data and compared with the standard DAS beam-former. It is shown that the MVDR algorithm performs better in terms of higher resolution and better side lobe and mode suppression capabilities. Known issues of the MVDR approach, such as signal cancellation in highly correlated environments and poor robustness, are addressed using methods that have proven effective for the purpose in other fields of active imaging.

关键词： LAMB WAVES tool monitor Adaptive Beam forming plate structure two-dimensional array sidelobe frequency selectivity arrays

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