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A chaos-based image encryption algorithm with variable control parameters

CHAOS SOLITONS & FRACTALS 2009年第4期41卷 1773-1783页

作者： Wang, Yong Wong, Kwok-Wo Liao, Xiaofeng Xiang, Tao Chen, Guanrong Chongqing Univ Posts & Telecommun Key Lab Elect Commerce & Logist Chongqing Chongqing 400065 Peoples R China City Univ Hong Kong Dept Elect Engn Kowloon Tong Hong Kong Peoples R China Chongqing Univ Dept Comp Sci & Engn Chongqing 400044 Peoples R China

In recent years, a number of image encryption algorithms based oil the permutation-diffusion structure have been proposed. However, the control parameters used in the permutation stage are Usually fixed in the whole encryption process. which favors attacks. In this paper, a chaos-based image encryption algorithm with variable control parameters is proposed. The control parameters used in the permutation stage and the keystream employed in the diffusion stage are generated from two chaotic maps related to the plain-image. As a result, the algorithm can effectively resist all known attacks against permutation-diffusion architectures. Theoretical analyses and computer simulations both confirm that the new algorithm possesses high security and fast encryption speed for practical image encryption. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： computer algorithms IMAGE processing DATA encryption (computer science) CONTROL theory (Mathematics) VARIABLES (Mathematics) PARAMETER estimation PERMUTATIONS DIFFUSION processes

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A Superresolution Image Reconstruction Algorithm Based on Landweber in Electrical Capacitance Tomography

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MATHEMATICAL PROBLEMS IN ENGINEERING 2013年第1期2013卷 1-8页

作者： Chen Deyun Li Zhiqiang Gao Ming Wang Lili Yu Xiaoyang Harbin Univ Sci & Technol Higher Educ Key Lab Measuring & Control Technol & Harbin Peoples R China

According to the image reconstruction accuracy influenced by the "soft field" nature and ill-conditioned problems in electrical capacitance tomography, a superresolution image reconstruction algorithm based on Landweber is proposed in the paper, which is based on the working principle of the electrical capacitance tomography system. The method uses the algorithm which is derived by regularization of solutions derived and derives closed solution by fast Fourier transform of the convolution kernel. So, it ensures the certainty of the solution and improves the stability and quality of image reconstruction results. Simulation results show that the imaging precision and real-time imaging of the algorithm are better than Landweber algorithm, and this algorithm proposes a new method for the electrical capacitance tomography image reconstruction algorithm.

关键词： HIGH resolution imaging IMAGE reconstruction algorithms ELECTRICAL capacitance tomography computer algorithms REGULARIZATION (Mathematics) computer simulation

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SPARC: Structural properties associated with residue constraints

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COMPUTATIONAL AND STRUCTURAL BIOTECHNOLOGY JOURNAL 2022年 20卷 1702-1715页

作者： Neuwald, Andrew F. Yang, Hui Nixon, Tracy Univ Maryland Sch Med Inst Genome Sci Dept Biochem & Mol Biol 670 W Baltimore Steet Baltimore MD 21201 USA Penn State Univ Dept Biol 304A Frear South Bldg University Pk PA 16802 USA Dept Biochem & Mol Biol 335 Frear South Bldg University Pk PA 16802 USA Schrodinger Inc New York NY 10036 USA

SPARC facilitates the generation of plausible hypotheses regarding underlying biochemical mechanisms by structurally characterizing protein sequence constraints. Such constraints appear as residues co conserved in functionally related subgroups, as subtle pairwise correlations (i.e., direct couplings), and as correlations among these sequence features or with structural features. SPARC performs three types of analyses. First, based on pairwise sequence correlations, it estimates the biological relevance of alternative conformations and of homomeric contacts, as illustrated here for death domains. Second, it estimates the statistical significance of the correspondence between directly coupled residue pairs and interactions at heterodimeric interfaces. Third, given molecular dynamics simulated structures, it characterizes interactions among constrained residues or between such residues and ligands that: (a) are stably maintained during the simulation;(b) undergo correlated formation and/or disruption of interactions with other constrained residues;or (c) switch between alternative interactions. We illustrate this for two homohexameric complexes: the bacterial enhancer binding protein (bEBP) NtrC1, which activates transcription by remodeling RNA polymerase (RNAP) containing r54, and for DnaB helicase, which opens DNA at the bacterial replication fork. Based on the NtrC1 analysis, we hypothesize possible mechanisms for inhibiting ATP hydrolysis until ADP is released from an adjacent subunit and for coupling ATP hydrolysis to restructuring of sigma(54) binding loops. Based on the DnaB analysis, we hypothesize that DnaB 'grabs' ssDNA by flipping every fourth base and inserting it into cavities between subunits and that flipping of a DnaB-specific glutamine residue triggers ATP hydrolysis. (C) 2022 The Authors. Published by Elsevier B.V. on behalf of Research Network of Computational and Structural Biotechnology.& nbsp

关键词： Bayesian Markov chain Monte Carlo Direct coupling analysis computer algorithms

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Reliable Flash Calculations: Part 1. Nonsmooth Inside-Out algorithms

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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 2017年第4期56卷 960-973页

作者： Watson, Harry A. J. Vikse, Matias Gundersen, Truls Barton, Paul I. MIT Proc Syst Engn Lab 77 Massachusetts Ave Cambridge MA 02139 USA Norwegian Univ Sci & Technol Dept Energy & Proc Engn NO-7491 Trondheim Norway

Dependable algorithms for nonideal vapor liquid equilibrium calculations are essential for effective process design, simulation, and optimization. Inside-out algorithms [Boston, J.;Britt, H. Comput. Chem. Eng. 1978, 2, 109] for flash calculations serve as the basis for many of the algorithms used by process simulation software due to their robustness with respect to initialization and inexpensive computational cost. However, if the specified flash conditions imply a single-phase result, the conventional inside-out algorithms fail, as the solution is constrained to obey equilibrium relationships, which are only valid in the two-phase region. These incorrect results can be postprocessed to determine the true single-phase solution;however, such approaches either carry a high computational cost or are heuristic in nature and vulnerable to failure (or both). Such attributes are undesirable in a process simulation/optimization problem where many flash calculations must be performed for streams where the phase regime at the solution is not known a priori. To address this issue, this article presents modifications of the classical inside-out algorithms using a nonsmooth equation system in the inner loop to relax equilibrium conditions when necessary, allowing reliable convergence to single-phase results. Numerical results for simulations involving several common flash types and property packages are shown, highlighting the capability of the new nonsmooth algorithms for handling both two-phase and single-phase behavior robustly and efficiently.

关键词： NONSMOOTH optimization computer algorithms VAPOR-liquid equilibrium ROBUST control COMPUTATIONAL chemistry

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A mixed pixel- and region-based approach for using airborne laser scanning data for individual tree crown delineation in Pinus radiata D. Don plantations

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2013年第21期34卷 7671-7690页

作者： Gonzalez-Ferreiro, Eduardo Dieguez-Aranda, Ulises Barreiro-Fernandez, Laura Bujan, Sandra Barbosa, Miguel Suarez, Juan C. Bye, Iain J. Miranda, David Univ Santiago de Compostela Dept Agroforestry Engn Land Lab Lugo 27002 Spain Univ Santiago de Compostela Sustainable Forest Management Unit Dept Agroforestry Engn Lugo 27002 Spain Univ Porto Dept Geosci Environm & Terr P-4169007 Oporto Portugal Forestry Commiss Roslin No Res Stn Roslin EH25 9SY Midlothian Scotland

The aim of this study was to evaluate the use of high-resolution airborne laser scanner (ALS) data to detect and measure individual trees. We developed and tested a new mixed pixel- and region-based algorithm (using Definiens Developer 7.0) for locating individual tree positions and estimating their total heights. We computed a canopy height model (CHM) of pixel size 0.25m from dense first-pulse point data (8 pulses m(-2)) acquired with a small-footprint discrete-return lidar sensor. We validated the results of individual tree segmentation with accurate field measurements made in 37 plots of Monterey pine (Pinus radiata D. Don) distributed over an area of 36 km(2). Fieldwork consisted of labelling all of the trees in each plot and measuring their height and position, for posterior integration of the data from both sources (field and lidar). The proposed algorithm correctly detected and linked 59.8% of the trees in the 37 sample plots. We also manually located the trees by using FUSION software to visualize the raw lidar data cloud. However, because the latter method is extremely time-consuming, we only considered 10 randomly selected plots. Manual location correctly detected and linked 71.9% of the trees (in this subsample the algorithm correctly detected and measured 63.5% of the trees). The R-2 values for the linear model relating field- and lidar-measured heights of the linked trees located manually and with the automatic location algorithm were 0.90 and 0.88, respectively.

关键词： OPTICAL scanners TREES -- Measurement computer algorithms HEMISPHERICAL photography LIDAR (Optics) PINUS radiata

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The method of characteristics in ideal plasticity problems

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PMM JOURNAL OF APPLIED MATHEMATICS AND MECHANICS 2012年第5期76卷 497-505页

作者： Annin, B. D. Klunnikova, M. M. Sadovskaya, O. V. Sadovskii, V. M. Novosibirsk and Krasnoyarsk Russia

A universal computer algorithm and computer program is developed that implements a direct version of the method of characteristics for solving systems of quasilinear first-order partial differential equations in two independent variables. The algorithm is used to calculate the lattice of slip lines and the velocity vector field in problems of the limiting equilibrium of ideally plastic and friable media. Results of the numerical solution of an ideal plasticity problem for a plane with an aperture loaded with an internal pressure, of the plane problem of the limiting equilibrium of a friable medium and of the axisymmetric problem of a rotating punch on the surface of a plastic half-space are presented to demonstrate the efficiency of the method. (c) 2012 Published by Elsevier Ltd.

关键词： PLASTICITY computer algorithms computer programming PROBLEM solving QUASILINEARIZATION DIFFERENTIAL equations

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Improvement in Laser-Irradiation Efficiency of Robot-Assisted Laser Hair Removal Through Pose Measurement of Skin Surface

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PHOTOMEDICINE AND LASER SURGERY 2016年第1期34卷 42-49页

作者： Park, Sungwoo Lim, Hyoung-woo Cho, Minwoo Lee, Dong-Hun Koh, Wooseok Kim, Youdan Chung, Jin Ho Kim, Sungwan Seoul Natl Univ Coll Engn Interdisciplinary Program Bioengn Seoul 110799 South Korea Seoul Natl Univ Coll Med Dept Dermatol Inst Human Environm Interface Biol Seoul 110799 South Korea JMO Dermatol Seoul South Korea Seoul Natl Univ Coll Engn Inst Adv Aerosp Technol Dept Mech & Aerosp Engn Seoul 110799 South Korea Seoul Natl Univ Coll Med Dept Biomed Engn Seoul 110799 South Korea Seoul Natl Univ Inst Med & Biol Engn Seoul 110799 South Korea

Objective: This study aims to improve the performance of an automatic laser hair removal (LHR) system by applying an algorithm that considers the curve and slant of the skin surface. Background data: In an earlier research, a robot-assisted LHR system has been developed and validated for an almost flat skin or a relatively smooth curved part of the skin. For practical clinical applications, the feature of the robot-assisted LHR system is extended for real curved skins. Methods: A novel pose-measurement algorithm is developed and applied to the LHR system. This system detects a six-degree of freedom (DOF) pose of the skin surface using the pose-measurement algorithm. The main principle of this algorithm is finding the equation of a plane using three noncollinear points, which are obtained by sequential movement of a one dimensional laser sensor. Results: Evaluation of the proposed system was conducted. During the test, we demonstrated that the LHR device automatically and completely contacted the targets along the curved surface. The contact-accuracy test produced satisfactory outcome. The averages of the root mean square (RMS) of the position error and the RMS of the rotation were 1.4437mm and 1.0982 degrees, respectively. The curvature measurement test produced a satisfactory average result of 0.0006mm RMS error. Conclusions: Using the proposed six-DOF pose-measurement algorithm, the performance of the robot-assisted LHR system could be significantly improved from the clinical point of view because most real skins have curved shapes.

关键词： Hair removal Laser beams Robotics in medicine computer algorithms Pose estimation (computer vision) Skin -- Physiology

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Modeling Multioperator Multi-UAV Operator Attention Allocation Problem Based on Maximizing the Global Reward

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MATHEMATICAL PROBLEMS IN ENGINEERING 2016年第1期2016卷 1-8页

作者： Wu, Yuhang Huang, Zhonghua Li, Yinlin Wang, Zhiqi Beijing Inst Technol Sch Mechatron Engn Beijing 100081 Peoples R China

This paper focuses on the attention allocation problem (AAP) in modeling multioperator multi-UAV (MOMU), with the operator model and task properties taken into consideration. Themodel ofMOMUoperator AAP based onmaximizing the global reward is established and used to allocate tasks to all operators as well as set work time and rest time to each task simultaneously for operators. The proposed model is validated in Matlab simulation environment, using the immune algorithm and dynamic programming algorithm to evaluate the performance of the model in terms of the reward value with regard to the work time, rest time, and task allocation. The result shows that the total reward of the proposed model is larger than the one obtained from previously published methods using local maximization and the total reward of our method has an exponent-like relation with the task arrival rate. The proposed model can improve the operators' task processing efficiency in the MOMU command and control scenarios.

关键词： DRONE aircraft ASSIGNMENT problems (Programming) computer algorithms DYNAMIC programming

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A Decentralized Control Algorithm for Large-Scale Building Structures

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computer-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING 2012年第1期27卷 2-13页

作者： Lei, Ying Wu, D. T. Lin, Y. Xiamen Univ Dept Civil Engn Xiamen 361005 Peoples R China

Decentralized control strategy is more suitable for structural control of large-scale structural systems as it increases in the feasibility of control implementation and decreases the risk on the failure of the control system compared with the conventional centralized control approach. In this article, a decentralized control algorithm is proposed for large-scale linear building structures. A large-scale building structure is divided into a set of smaller substructures based on its finite element model. Interconnections between adjacent substructures are treated as disturbances to the individual substructure. Each substructure is controlled by its own local controller using linear quadratic Gaussian control scheme with acceleration measurements as feedback signals. A computational procedure is developed for the recursive estimation of the unknown disturbances to each substructure. Two cases, with substructure interface measurement and without substructure interface measurement respectively, are considered. A numerical example of the decentralized control of the 20-story Structural Engineers Association of California (SAC) benchmark linear building under seismic excitation is studied to evaluate the performance of the proposed algorithm. Simulation results demonstrate that the decentralized control algorithm has quite good control performance compared with the conventional centralized control approach. Therefore, the proposed decentralized control algorithm is viable for structural control of large-scale linear structural systems.

关键词： linear quadratic Gaussian control control systems control performance acceleration measurement numerical example Substructures computer algorithms Structural systems computational procedure INTEGRATED SHIP CONTROL decentralised control structure control recursive estimation decentralized control algorithm built structure

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Novel data association schemes for the probability hypothesis density filter

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2007年第2期43卷 556-570页

作者： Panta, Kusha Vo, Ba-Ngu Singh, Sumeetpal Univ Melbourne Co Operat Res Ctr Sensor & Informat Proc Dept Elect & Elect Engn Melbourne Vic 3010 Australia Univ Melbourne Dept Elect & Elect Engn Cambridge CB2 1PZ England

The probability hypothesis density (PHD) filter is a practical alternative to the optimal Bayesian multi-target filter based on finite set statistics. It propagates the PHD function, a first-order moment of the full multi-target posterior density. The peaks of the PHD function give estimates of target states. However, the PHD filter keeps no record of target identities and hence does not produce track-valued estimates of individual targets. We propose two different schemes according to which PHD filter can provide track-valued estimates of individual targets. Both schemes use the probabilistic data-association functionality albeit in different ways. In the first scheme, the outputs of the PHD filter are partitioned into tracks by performing track-to-estimate association. The second scheme uses the PHD filter as a clutter filter to eliminate some of the clutter from the measurement set before it is subjected to existing data association techniques. In both schemes, the PHD filter effectively reduces the size of the data that would be subject to data association. We consider the use of multiple hypothesis tracking (MHT) for the purpose of data association. The performance of the proposed schemes are discussed and compared with that of MHT.

关键词： PROBABILITY measures TRACKING radar HYPOTHESIS STATISTICS DENSITY functionals computer algorithms GAUSSIAN processes RADIO filters ELECTRONICS

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