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SOFTWARE FOR GAMMA CAMERAS FOR MAPPING RADIOACTIVE CONTAMINATION

ATOMIC ENERGY 2010年第3期108卷 214-222页

作者： Ivanov, O. P. IV Kurchatov Atom Energy Inst Russian Sci Ctr Moscow 123182 Russia

The software for portable systems for obtaining. image with coding apertures (masks) is described. The software developed controls all systems that form an image and obtain shadow patterns, reconstructs the initial gamma-image, and processes previously obtained images. The software is used with portable systems in which URA and MURA type masks with different rank are used as the coding aperture. Programs for modeling the process of obtaining shadow patterns using real apparatus which has different position-sensitive detectors are described. Possible configurations of new apparatus which could be of practical interest are examined.

关键词： COMPUTER software development GAMMA rays CAMERAS MAPPINGS (Mathematics) RADIOACTIVE substances coding theory DETECTORS

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On the Duality of Probing and Fault Attacks

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JOURNAL OF ELECTRONIC TESTING-theory AND APPLICATIONS 2010年第4期26卷 483-493页

作者： Gammel, Berndt M. Mangard, Stefan Infineon Technol AG Munich Germany

In this work we investigate the problem of simultaneous privacy and integrity protection in cryptographic circuits. We consider a white-box scenario with a powerful, yet limited attacker. A concise metric for the level of probing and fault security is introduced, which is directly related to the capabilities of a realistic attacker. In order to investigate the interrelation of probing and fault security we introduce a common mathematical framework based on the formalism of information and coding theory. The framework unifies the known linear masking schemes. We proof a central theorem about the properties of linear codes which leads to optimal secret sharing schemes. These schemes provide the lower bound for the number of masks needed to counteract an attacker with a given strength. The new formalism reveals an intriguing duality principle between the problems of probing and fault security, and provides a unified view on privacy and integrity protection using error detecting codes. Finally, we introduce a new class of linear tamper-resistant codes. These are eligible to preserve security against an attacker mounting simultaneous probing and fault attacks.

关键词： Probing attacks Fault attacks Side channel attacks coding theory Secret sharing Secure computation

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Influence of near-wall modelling on boiling flow simulation

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NUCLEAR ENGINEERING AND DESIGN 2010年第2期240卷 275-283页

作者： Koncar, Bostjan Tiselj, Iztok Jozef Stefan Inst SI-1000 Ljubljana Slovenia

The capability of the three-dimensional two-fluid codes to simulate the local boiling flow processes has been assessed. Boiling flow experiments of Roy et al. [Roy, R.P., Kang, S., Zarate, J.A., Laporta, A., 2002. Turbulent subcooled boiling flow-experiments and simulations, J. Heat Transfer 124, 73-93] and Lee et al. [Lee, T.H., Park, G.C., Lee, DJ., 2002. Local flow characteristics of subcooled boiling flow of water in a vertical concentric annulus. Int. J. Multiphase Flow 28, 1351-1368], both performed in annular vertical channels were used as an experimental benchmark data set. The boiling flow is strongly affected by local mechanisms in the boundary layer near the heated wall. In this paper, the influence of near-wall modelling on the distribution of flow parameters at flow boiling has been analyzed. A generic wall function model for 3D two-fluid codes, based on surface roughness analogy has been proposed instead of commonly used single-phase log-law model. The new model has been implemented in the code CFX-4.4. In general, better agreement of phase velocities with experimental data were obtained with the new model. Presented results show that the influence of nucleating bubbles on the near-wall velocity profile should be taken into account. The second goal of this paper is to compare the NEPTUNE-CFD simulations against CFX-4.4 results and experimental data. (C) 2008 Elsevier B.V. All rights reserved.

关键词： TWO-phase flow BOILING water reactors TURBULENCE COMPUTATIONAL fluid dynamics coding theory BOUNDARY layer (Aerodynamics) SIMULATION methods & models

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Wireless broadcasting using XOR coding

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ELECTRONICS LETTERS 2010年第25期46卷 1700-1701页

作者： Juang, R. -T. Yar, K. -P. Lin, H. -P. Lin, D. -B. Ind Technol Res Inst Informat & Commun Res Labs Hsinchu 310 Taiwan ASTAR Inst Infocomm Res Singapore Singapore Natl Taipei Univ Technol Inst Comp & Commun Engn Taipei Taiwan

Based on XOR coding, proposed is a proactive broadcasting for wireless broadcast systems where multiple faulty packets can be rectified at the cost of transmitting an additional coded packet. Since it greatly outstrips the conventional one in terms of BER performance, the proposed scheme can aggressively allocate the transmission rate to compensate for its throughput penalty. Numerical simulations show that the proposed scheme outperforms its conventional counterpart for about 5 dB SNR at a target BER of 10(-3) for an OFDM system.

关键词： WIRELESS communication systems BROADCASTING industry DATA encryption (Computer science) DATA transmission systems coding theory DATA packets & packeting COMPUTER simulation

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Link adaptation based on repetition coding for mobile worldwide interoperability for microwave access systems

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IET COMMUNICATIONS 2010年第9期4卷 1039-1048页

作者： Juang, R. -T. Ting, P. Lin, H. -P. Lin, D. -B. Ind Technol Res Inst Hsinchu Taiwan Natl Taipei Univ Technol Inst Comp & Commun Engn Taipei Taiwan

Worldwide interoperability for microwave access (WiMAX) suffers from inter-carrier interference (ICI) since it adopts orthogonal frequency division multiplexing in physical layer. This study applies a repetition coding scheme, which encodes the same data on a subcarrier pair, to the hierarchical modulation to suppress the ICI and thus the inter-layer interference. Consequently, the proposed method mitigates the effects of fading and interference and provides a finer granularity of modulation order for link adaptation. Besides, the repetition coding scheme is also applied to a hybrid automatic repeat request (HARQ) protocol to recover error packets because of poor channel conditions. The proposed method incorporates the ICI cancellation into the conventional incremental redundancy HARQ and automatically activates the cancellation of ICI without Doppler shift/mobility estimation. Simulations show that the proposed algorithms outperform the conventional schemes in time-varying Rayleigh fading channels, especially in high-mobility environments.

关键词： IEEE 802.16 (Standard) ALGORITHMS DATA transmission systems TELECOMMUNICATION RADIO transmitters & transmission -- Fading coding theory

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A Note on a Sampling Theorem for Functions over GF(q)ⁿ Domain

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2010年第6期E93A卷 1024-1031页

作者： Ukita, Yoshifumi Saito, Tomohiko Matsushima, Toshiyasu Hirasawa, Shigeichi Yokohama Coll Commerce Dept Management Informat Yokohama Kanagawa 2308577 Japan Aoyama Gakuin Univ Coll Sci & Engn Sagamihara Kanagawa 2298558 Japan Waseda Univ Dept Appl Math Tokyo 1698555 Japan Waseda Univ Res Inst Sci & Engn Tokyo 1698555 Japan Cyber Univ Tokyo 1620853 Japan

In digital signal processing, the sampling theorem states that any real valued function f can be reconstructed from a sequence of values of f that are discretely sampled with a frequency at least twice as high as the maximum frequency of the spectrum of f. This theorem can also be applied to functions over finite domain. Then, the range of frequencies of f can be expressed in more detail by using a bounded set instead of the maximum frequency. A function whose range of frequencies is confined to a bounded set is referred to as bandlimited function. And a sampling theorem for bandlimited functions over Boolean domain has been obtained. Here, it is important to obtain a sampling theorem for bandlimited functions not only over Boolean domain (GF(2)(n) domain) but also over GF(q)(n) domain, where q is a prime power and GF(q) is Galois field of order q. For example, in experimental designs, although the model can be expressed as a linear combination of the Fourier basis functions and the levels of each factor can be represented by GF(q), the number of levels often take a value greater than two. However, the sampling theorem for bandlimited functions over GF(q)(n) domain has not been obtained. On the other hand, the sampling points are closely related to the codewords of a linear code. However, the relation between the parity check matrix of a linear code and any distinct error vectors has not been obtained, although it is necessary for understanding the meaning of the sampling theorem for bandlimited functions. En this paper, we generalize the sampling theorem for bandlimited functions over Boolean domain to a sampling theorem for bandlimited functions over GF(q)(n) domain. We also present a theorem for the relation between the parity check matrix of a linear code and any distinct error vectors. Lastly, we clarify the relation between the sampling theorem for functions over GF(q)(n) domain and linear codes.

关键词： coding theory linear codes discrete Fourier transform experimental designs

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A mechanistic model of critical heat flux under subcooled flow boiling conditions for application to one- and three-dimensional computer codes

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NUCLEAR ENGINEERING AND DESIGN 2010年第2期240卷 235-244页

作者： Le Corre, Jean-Marie Yao, Shi-Chune Amon, Cristina H. Westinghouse Elect Sweden AB S-72163 Vasteras Sweden Carnegie Mellon Univ Dept Mech Engn Pittsburgh PA 15213 USA Univ Toronto Fac Engn & Appl Sci Toronto ON M5S 1A4 Canada

Based on a review of visual observations at or near critical heat flux (CHF) under subcooled flow boiling conditions and consideration of CHF triggering mechanisms, presented in a companion paper [Le Corre, J.M., Yao, S.C., Amon, C.H., 2010. Two-phase flow regimes and mechanisms of critical heat flux under subcooled flow boiling conditions. Nucl. Eng. Des.], a model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. It is postulated that a high local wall superheat occurring underneath a nucleating bubble at the time of bubble departure can prevent wall rewetting at CHF (Leidenfrost effect). The model has also the potential to evaluate the post-DNB heater temperature up to the point of heater melting. Validation of the proposed model was performed using detailed measured wall boiling parameters near CHF, thereby bypassing most needed constitutive relations. It was found that under limiting nucleation conditions: a peak wall temperature at the time of bubble departure can be reached at CHF preventing wall cooling by quenching. The simulations show that the resulting dry patch can survive the surrounding quenching events, preventing further nucleation and leading to a fast heater temperature increase. The model was applied at CHF conditions in simple geometry coupled with one-dimensional and three dimensional (CFD) codes. It was found that, within the range where CHF occurs under bubbly flow conditions (as defined in Le Corre et al., this issue), the local wall superheat underneath nucleating bubbles is predicted to reach the Leidenfrost temperature. However, a better knowledge of statistical variations in wall boiling parameters would be necessary to correctly capture the CHF trends wi

关键词： PRESSURIZED water reactors -- Critical heat flux COMPUTATIONAL fluid dynamics coding theory THERMAL analysis NUCLEATION VISUALIZATION COOLING COMPUTER simulation

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HARDNESS OF RECONSTRUCTING MULTIVARIATE POLYNOMIALS OVER FINITE FIELDS

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SIAM JOURNAL ON COMPUTING 2010年第6期39卷 2598-2621页

作者： Gopalan, Parikshit Khot, Subhash Saket, Rishi Microsoft Res Silicon Valley Mountain View CA 94043 USA Univ Washington Seattle WA 98195 USA Univ Texas Austin Austin TX 78712 USA New York Univ Dept Comp Sci New York NY 10012 USA Georgia Tech Coll Comp Atlanta GA 30332 USA

We study the polynomial reconstruction problem for low-degree multivariate polynomials over finite field F[2]. In this problem, we are given a set of points x is an element of {0, 1}(n) and target values f(x) is an element of {0, 1} for each of these points, with the promise that there is a polynomial over F[2] of degree at most d that agrees with f at 1-epsilon fraction of the points. Our goal is to find a degree d polynomial that has good agreement with f. We show that it is NP-hard to find a polynomial that agrees with f on more than 1-2(-d) + delta fraction of the points for any epsilon, delta > 0. This holds even with the stronger promise that the polynomial that fits the data is in fact linear, whereas the algorithm is allowed to find a polynomial of degree d. Previously the only known hardness of approximation (or even NP-completeness) was for the case when d = 1, which follows from a celebrated result of Hastad [J. ACM, 48 (2001), pp. 798-859]. In the setting of Computational Learning, our result shows the hardness of nonproper agnostic learning of parities, where the learner is allowed a low-degree polynomial over F[2] as a hypothesis. This is the first nonproper hardness result for this central problem in computational learning. Our results can be extended to multivariate polynomial reconstruction over any finite field.

关键词： hardness of approximation polynomials finite fields coding theory computational learning

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ON MULTIDIMENSIONAL CONVOLUTIONAL CODES AND CONTROLLABILITY PROPERTIES OF MULTIDIMENSIONAL SYSTEMS OVER FINITE RINGS

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ASIAN JOURNAL OF CONTROL 2010年第2期12卷 119-126页

作者： Zerz, Eva Rhein Westfal TH Aachen Lehrstuhl Math D D-52062 Aachen Germany

Using the behavior-code duality pointed out by Rosenthal et al., we study the relations between certain desirable features of a code and the corresponding controllability properties of its behavior. Module-theoretic characterizations are provided as well. The coefficients of the codes and behaviors are taken to be integers modulo in, where in is not necessarily prime.

关键词： Linear systems systems over rings algebraic methods behavioral approach coding theory

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Laser-induced breakdown method for code detection (identification) in explosion products of coded explosives

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INORGANIC MATERIALS 2010年第14期46卷 1487-1492页

作者： Karasevich, Yu. K. Kulagin, A. Yu. Skripkin, A. M. Khatyushin, P. A. Karpov, Yu. A. Typhoon Res & Prod Assoc Obninsk 249038 Kaluga Oblast Russia Russian Acad Sci NN Semenov Chem Phys Inst Moscow 119991 Russia State Res & Project Inst Rare Met Ind GIREDMET Moscow 109017 Russia

The results of a study on the development of a method for coding explosives are presented. As coding additives (CAs), it is proposed to use aluminum alloy powders with dosed amounts of rare-earth coding elements (CEs). This choice is dictated by the fact that aluminum alloys are commonly used as efficient additives in explosive compositions, while rare-earth elements are used as additives in technological operations, but are absent in the composition of standard explosives. In this case, the key to information on a given explosive and its manufacturer is the ratio of CE concentrations determined when analyzing explosives, e.g., when investigating an act of terrorism. Examples of explosion product decoding using a LIES laser-spark express analyzer.

关键词： EXPLOSIVES detection coding theory ALUMINUM alloys POWDERS RARE earths TERRORISM LASERS -- Industrial applications INDUCTIVELY coupled plasma atomic emission spectrometry

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