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A hybrid two-dimensional path planning model based on frothing construction algorithm and local fast marching method

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computerS & ELECTRICAL ENGINEERING 2013年第2期39卷 475-487页

作者： Yu, Chong Qiu, Qiwen Chen, Xiong Fudan Univ Sch Informat Sci & Technol Shanghai 200433 Peoples R China Bosch Automot Prod Suzhou Co Ltd Suzhou 215021 Peoples R China

To plan a global path in grid map, a hybrid two-dimensional path planning model based on frothing construction algorithm and local fast marching method is proposed. The proposed model consists of three steps. In first step, frothing construction algorithm is adopted to describe topology relationship of global passable regions in two-dimensional environment, and a grid topology map is obtained. The second step is path planning in topology map. Adopting generalized level-set algorithm, global shortest topology path can be obtained. In order to optimize the global path and real-time capability, global path replanning in grid map is proposed in third step. Local fast matching method is proposed by limiting effective region of cost potential function in global fast matching method. Quantitative analysis and comparisons prove that the proposed model is more suitable to the increasingly demanding path planning requirements than most of state-of-the-art algorithms. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： HYBRID systems computer algorithms FAST marching method (Mathematics) BOUNDARY value problems DIMENSIONAL analysis GENERALIZATION

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Testbed Validation of Location-Scheduled Control of a Reconfigurable Flux-Pinned Spacecraft Formation

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JOURNAL OF SPACECRAFT AND ROCKETS 2013年第6期50卷 1235-1247页

作者： Sorgenfrei, Matthew C. Jones, Laura L. Joshi, Sanjay S. Peck, Mason A. Univ Calif Davis Dept Mech & Aerosp Engn Davis CA 95616 USA Cornell Univ Dept Mech & Aerosp Engn Ithaca NY 14850 USA

Unique mission architectures become possible when formations of close-proximity spacecraft have the ability to reconfigure on orbit to adapt to different mission requirements. A necessary precursor to the realization of these missions, however, is the development of control architectures that accommodate the different geometries of a reconfigurable space system at different mission phases. This paper investigates the closed-loop control of a reconfigurable set of two CubeSat-scale spacecraft that are connected via noncontacting flux-pinned interfaces. A design concept known as location-scheduled control is used both to tune a Proportional-Integral-Derivative control law and to choose an optimal configuration for the spacecraft formation during a rest-to-rest reorientation maneuver. The location-scheduled control approach makes use of a genetic algorithm to search the design space of configurations and controller gains. The simulated performance of the controller is compared to experiments performed on Cornell University's Float Cube testbed, a planar air-bearing environment for validating nanosatellite-scale spacecraft architectures. The system's performance using the location-scheduled control-derived gains shows the same trends in the simulated and experimental data while providing insight into the behavior of the flux-pinned interfaces. Both simulation and experimental results also suggest that the location-scheduled control algorithm can select a combination of controller gains and system configuration that outperforms a human engineer's informed trial-and-error search.

关键词： System performance optimal configuration mission architecture Geologic Formations aerospace systems design concept configurability Spacecraft Controllers simulating Religious Missions computer algorithms

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Real-Time Hardware-in-the-Loop Laboratory Testing for Multisensor Sense and Avoid Systems

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INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING 2013年第1期2013卷 9.1-9.9页

作者： Fasano, Giancarmine Accardo, Domenico Forlenza, Lidia Renga, Alfredo Rufino, Giancarlo Tancredi, Urbano Moccia, Antonio Univ Naples Federico II Dept Ind Engn DII I-80125 Naples Italy Univ Naples Parthenope Ctr Direz Dept Technol I-80143 Naples Italy

This paper focuses on a hardware-in-the-loop facility aimed at real-time testing of architectures and algorithms of multisensor sense and avoid systems. It was developed within a research project aimed at flight demonstration of autonomous non-cooperative collision avoidance for Unmanned Aircraft Systems. In this framework, an optionally piloted Very Light Aircraft was used as experimental platform. The flight system is based on multiple-sensor data integration and it includes a Ka-band radar, four electro-optical sensors, and two dedicated processing units. The laboratory test system was developed with the primary aim of prototype validation before multi-sensor tracking and collision avoidance flight tests. System concept, hardware/software components, and operating modes are described in the paper. The facility has been built with a modular approach including both flight hardware and simulated systems and can work on the basis of experimentally tested or synthetically generated scenarios. Indeed, hybrid operating modes are also foreseen which enable performance assessment also in the case of alternative sensing architectures and flight scenarios that are hardly reproducible during flight tests. Real-time multisensor tracking results based on flight data are reported, which demonstrate reliability of the laboratory simulation while also showing the effectiveness of radar/electro-optical fusion in a non-cooperative collision avoidance architecture.

关键词： REAL-time computing HARDWARE-in-the-loop simulation SENSOR networks computer architecture computer algorithms COLLISIONS (Nuclear physics) DRONE aircraft ELECTROOPTICAL devices

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Slot assignment strategy to reduce loss of capacity of contiguous-slot path requests in flexible grid optical networks

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ELECTRONICS LETTERS 2013年第5期49卷 359-360页

作者： Almeida, R. C., Jr. Santos, A. F. Assis, K. D. R. Waldman, H. Martins-Filho, J. F. Fed Univ Pernambuco UFPE Recife PE Brazil Fed Univ Bahia UFBA Salvador BA Brazil Fed Univ ABC UFABC Santo Andre SP Brazil

The performance improvement imparted by routing and spectrum assignment on flexible grid optical networks is a subject of current extensive investigation. Proposed is an efficient spectrum-assignment algorithm based on reducing the loss of capacity of future bandwidth-variable path requests. In all scenarios analysed the proposed algorithm outperformed currently investigated slot assignment algorithms.

关键词： OPTICAL communications ROUTING (computer network management) WAVELENGTH division multiplexing BANDWIDTHS computer algorithms BOOLEAN functions (Mathematics)

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Oscillator Frequency Offset Impact on Software GPS Receivers and Correction algorithms

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2013年第4期49卷 2158-2178页

作者： Kou, Yanhong Morton, Yu Beihang Univ Sch Elect & Informat Engn Beijing 100191 Peoples R China Miami Univ Dept Elect & Comp Engn Oxford OH 45056 USA

Software-based Global Positioning System (GPS) receivers have been recognized as an effective research platform in recent years. The impact of oscillator frequency offset on hardware receiver and software receiver signal processing is contrasted based on a refined signal model and cross correlation function (CCF) analysis. Several online clock error correction algorithms are presented to produce unbiased measurements and clock error estimates with known and unknown front end frequency plans and with and without signal tracking and navigation solutions for single-and dual-frequency receivers on both static and dynamic platforms. The CCF formulation and the clock correction performance are validated using simulated signals and real single-and dual-frequency GPS data. The raw frequency error measurements with 0.02 s time resolution for an oven controlled crystal oscillator (OCXO) using real GPS signal report an Allan deviation (ADEV) of 1.3E-11 and a standard deviation of 1.56E-11.

关键词： computer software GLOBAL Positioning System LINE receivers (Integrated circuits) computer algorithms CROSS correlation (Mathematics) SIGNAL processing MEASUREMENT errors CRYSTAL oscillators

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A steganalysis by adjacency pixel bits structure

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computerS & ELECTRICAL ENGINEERING 2013年第2期39卷 488-496页

作者： Tang, Mingwei Hu, Jie Fan, Mingyu Song, Wen Xihua Univ Sch Math & Comp Sci Technol Chengdu 610039 Peoples R China Univ Elect Sci & Technol China Sch Comp Sci & Engn Chengdu 610054 Peoples R China Southwest Jiaotong Univ Sch Informat Sci & Technol Chengdu 610031 Peoples R China

Embedding of confidential data in the least significant bit of an image is still an attractive method of steganography. Utilizing the full capacity of cover images by embedding one bit of data per pixel, using methods such as LSB flipping or LSB matching, usually decreases the security, making the algorithm vulnerable to steganalytic attacks. And then, it is proposed by an efficient high payload +/- 1 data embedding scheme(EPES) based on a special two variable binary function. This function uses the information of the least two significant bit planes of the cover image for the embedding and extraction purposes. Rather than randomly selecting +1 or -1, EPES achieves higher embedding efficiencies by choosing the correct modification component. The steganalytic method based on sample pair analysis (SPA) cannot effectively detect EPES. Hence, we propose a steganalysis by constructing adjacency pixel bits structure (SAP). The resulting detection algorithm is simple and fast. Analytical and experimental results demonstrate that the proposed method provides;higher detecting efficiency than the other steganalysis. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： PIXELS DATA analysis IMAGE processing CRYPTOGRAPHY EMBEDDED computer systems computer algorithms computer security

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Improved algorithm for navigation of rescue robots in underground mines

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computerS & ELECTRICAL ENGINEERING 2013年第4期39卷 1088-1094页

作者： Tian, Zijian Zhang, Liya Chen, Wei China Univ Min & Technol State Key Lab Coal Resources & Safe Min Beijing 100083 Peoples R China China Univ Min & Technol Sch Comp Sci & Technol Xuzhou 221116 Peoples R China

Mine rescue robots play a vital role during rescues in underground mine disasters. In this paper, we propose a new navigation method by using diverse-sensor data fusion with an improved algorithm of the Neural Network Extended Kalman Filter. During this process, we take into account that a rescue's effectiveness is limited by its single navigation model. First, we utilize the Back Propagation neural network to improve the data matching level of dissimilar sensors. Second, data fusion is carried out by combining the Extended Kalman Filter and the Back Propagation neural network. By doing so, we simultaneously retrain the Back Propagation neural network with the modified error signals. The experimental analysis showed that the algorithm can effectively deal with heterogeneous data fusion. It can also improve the convergent speed and time response of the algorithm, and further improve the accuracy of navigation. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： computer algorithms MINERAL industries NEURAL networks (computer science) UTILITY theory DETECTORS KALMAN filtering SIGNAL-to-noise ratio STOCHASTIC convergence

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Fault Detection and Isolation in Inertial Measurement Units Based on χ²-CUSUM and Wavelet Packet

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MATHEMATICAL PROBLEMS IN ENGINEERING 2013年第1期2013卷 1-10页

作者： de Oliveira, Elcio Jeronimo da Fonseca, Ijar Milagre Kuga, Helio Koiti Inst Aeronaut & Space Div Space Syst BR-12228904 Sao Jose Dos Campos SP Brazil Natl Inst Space Res Space Mech & Control Div BR-12227010 Sao Jose Dos Campos SP Brazil UNINOVE Comp Sci & Prod Engn BR-01504001 Sao Paulo Brazil

The aim of this paper is to present a fault detection algorithm(FDI) based on signal processing techniques developed for an inertial measurement unit (IMU) with minimal redundancy of fiber optic gyros. In this work the recursive median filter is applied in order to remove impulses (outliers) arising from data acquisition process and parity vector operations, improving the fault detection and isolation performance. The FDI algorithmis divided into two blocks: fault detection (FD) and fault isolation (FI). The FD part of the algorithmis used to guarantee the reliability of the isolation part and is based on parity vector analysis using chi(2)-CUSUM algorithm. The FI part is performed using parity space projection of the energy subbands obtained from wavelet packet decomposition. This projection is an extension of clustering analysis based on singular value decomposition (SVD) and principal component analysis (PCA). The results of the FD and FI algorithms have shown the effectiveness of the proposed method, in which the FD algorithm is capable of indicating the low-level step bias fault with short delay and a high index of correct decisions of the FI algorithm also with low-level step bias fault.

关键词： DEBUGGING in computer science WAVELETS (Mathematics) MEDIAN filters (Electronics) PRINCIPAL components analysis FACTOR analysis computer algorithms

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High-precision control of nonstationary aircrafts by roll angle

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AUTOMATION AND REMOTE CONTROL 2013年第5期74卷 875-884页

作者： Rutkovskii, V. Yu. Glumov, V. M. Sukhanov, V. M. Russian Acad Sci Trapeznikov Inst Control Sci Moscow Russia

Control algorithms ensuring high-precision control of an object under coordinate and parametric disturbances and noises are designed. This problem is solved by introducing an additional adaptive control loop synthesized on the basis of adaptive system theory with reference models. Several ways of simplifying the proposed adaptive algorithm are considered.

关键词： reference model control ring roll angle Systems Theory Adaptive systems Aircraft Coordinates computer algorithms fine control

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A Parallel Encryption Algorithm Based on Piecewise Linear Chaotic Map

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MATHEMATICAL PROBLEMS IN ENGINEERING 2013年第1期2013卷 1-7页

作者： Wang, Xizhong Chen, Deyun Harbin Univ Sci & Technol Sch Comp Sci & Technol Harbin 150080 Peoples R China

We introduce a parallel chaos-based encryption algorithm for taking advantage of multicore processors. The chaotic cryptosystem is generated by the piecewise linear chaotic map (PWLCM). The parallel algorithm is designed with a master/slave communication model with the Message Passing Interface (MPI). The algorithm is suitable not only for multicore processors but also for the single-processor architecture. The experimental results show that the chaos-based cryptosystem possesses good statistical properties. The parallel algorithm provides much better performance than the serial ones and would be useful to apply in encryption/decryption file with large size or multimedia.

关键词： PIECEWISE polynomial approximation POLYNOMIAL approximation MULTICORE processors (computers) CRYPTOSYSTEMS PARALLEL algorithms MESSAGE passing (computer science) computer algorithms

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