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International Conference on Universal Personal Communications

作者： A. Annamalai V.K. Bhargava Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

The throughput of conventional ARQ protocols, such as the stop-and-wait, go-back-N and selective-repeat, can be improved by dynamically adapting the protocol packet length with the changes in channel conditions. Such an action requires a method for sensing the channel state and detecting a change in it. This paper examines four simple algorithms to implement such an adaptive system in a slowly varying mobile radio channel. It is shown that these algorithms performs remarkably well in spite of their simplicity. In particular, the algorithm based on counting the contiguous positive and/or negative acknowledgment messages provides a reliable channel state information (CSI) within only a few block transmissions, and requires the shortest observation interval among the four schemes.

关键词： Automatic repeat request Error correction Programmable control Adaptive control change detection algorithms Protocols Throughput Adaptive systems Land mobile radio Channel state information

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Content-based video abstraction

Content-based video abstraction

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IEEE International Conference on Image Processing

作者： B. Gunsel A.M. Tekalp Department of Electrical Engineering and Center for Electronic Imaging Systems University of Rochester Rochester NY USA

The paper addresses automatic scene change detection, key frame selection, and similarity ranking which constitute the main steps of a content based video abstraction system. Unlike other methods, the proposed algorithm performs scene change detection and key frame selection in one step. We treat scene change detection as a two-class classification problem and employ automatic threshold selection techniques originally developed for image binarization. A quantitative measure for retrieval of similar scenes according to their color content is also defined. The described scheme can be applied to both uncompressed and MPEG compressed video, and can be implemented in real time. Performance of the algorithm has been analyzed on real TV sequences, and comparison with some previously introduced techniques are provided.

关键词： Layout change detection algorithms Content based retrieval Transform coding Image coding Video compression Image sequence analysis Performance analysis Algorithm design and analysis TV

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Fuzzy shot clustering to support networked video databases

Fuzzy shot clustering to support networked video databases

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： S. Auephanwiriyakul A. Joshi R. Krishnapuram University of Missouri Columbia MO USA

Video querying involves a lot of user interaction and feedback based query refinement, which can generate large traffic volumes on the network if full video segments are sent. For efficient video browsing, search and retrieval, one need to find good compact representations for long video sequences. Representative frames (Rframes) provide such a representation. Extant algorithms use scene change detection to segment video into shots and pick Rframes. However, scene change detection techniques fail badly in presence of gradual scene changes which are quite prevalent in most videos. We present another way of finding Rframe using fuzzy clustering without dealing with any scene change detection algorithms. Fuzzy clusters provide a more natural approach to this problem since membership of a frame in some particular scene is not binary. This allows one to handle gradual scene changes. We report on our approach, the initial experimental results and future plans.

关键词： Layout Video on demand Video compression Visual databases Video sequences change detection algorithms detection algorithms Feedback Clustering algorithms Gunshot detection systems

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Wipe scene change detector for segmenting uncompressed video sequences

Wipe scene change detector for segmenting uncompressed video...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： A.M. Alattar Electrical Engineering Department King Fahd University of Petroleum and Minerals Dhahran Saudi Arabia

The use of wipes in video production to smooth the transition between two consecutive scenes complicates subsequent video compression, video editing, and video database indexing. It is important to detect the wipe region in order to improve the quality of the compressed video or to allow automatic parsing of the video for the purpose of editing and data base indexing. In this paper, a model is developed for the wipe region and is used to derive the statistical characteristics of the frames in the wipe region. A wipe detector that exploits the linear change in the means and the variances of the frames in the wipe region is developed. The developed wipe detector is implemented and tested with video sequences containing wipes of different types and lengths. Simulation results indicate that wipe regions are well represented by the developed wipe model, and that the developed wipe detector is robust to wipe type and length.

关键词： Layout Detectors Video sequences Video compression Databases Indexing MPEG 7 Standard change detection algorithms Image coding Production

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Research of stationary partitions in nonstationary processes by measurement of spectral distance with the help of nondyadic Malvar's decomposition

Research of stationary partitions in nonstationary processes...

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IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis

作者： P. Carre C. Fernandez-Maloigne IRCOM-SIC Laboratory France

In this article, we propose a simple algorithm allowing the research of stationary partitions in locally stationary processes, by use of adapted local bases like the local DCT or the short-time Fourier transform. The algorithm aims at finding some windows of which width is adapted to the rate of change in the spectrum. A similar approach was proposed by Adak (1995), who detected changes over time in the spectra of the process to select a data-dependent window size. The same principle is used in our algorithm, with a more robust estimation of the difference in spectra than Adak. After denoising of the periodogram with the help of the undecimated wavelet transform, we consider the "symmetrical case" in the best partition selection method. A post-treatment permits us to deal with the nonuniform partitions.

关键词： Fourier transforms Partitioning algorithms Discrete wavelet transforms Noise reduction change detection algorithms Robustness Binary trees Discrete Fourier transforms Laboratories Discrete cosine transforms

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Very fast collision detection for practical motion planning. II. The parallel algorithm

Very fast collision detection for practical motion planning....

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IEEE International Conference on Robotics and Automation (ICRA)

作者： M. Perez-Francisco A.P. del Pobil B. Martinez-Salvador Department of Computer Science Jaume I University Castellon Spain

Practical robot motion planning for multiple moving objects in large complex scenarios requires very fast collision detection. We present an efficient algorithm for collision detection between multiple moving objects intended to be used for robot motion planning. It is based on our spherical representation for non-convex and curved object that are not partitioned into convex ones. We present results that show the stability of the approach with respect to the number of polygons used to model the scene. Numerical evidence of the efficiency of the algorithm is also shown by several experiments, in which we obtain average intersection detection times of around one millisecond using 8 or 11 processors for two closely moving robots involving 1,900 polygons.

关键词： Motion detection Parallel algorithms Motion planning Robot motion Partitioning algorithms Object detection Solid modeling change detection algorithms Stability Layout

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A simple recursive algorithm for diagnosis of abrupt changes in signals and systems

A simple recursive algorithm for diagnosis of abrupt changes...

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American Control Conference (ACC)

作者： I.V. Nikiforov Université de Technologie de Troyes Troyes France

We address the problem of detecting and isolating abrupt changes in signals and systems with random disturbances. An asymptotic optimal solution to this problem, which has been proposed in previous works, leads to the number of arithmetical operations at time t which grows to infinity with t. Moreover, the proposed criterion of optimality does not impose a constraint on the probability of false isolation when the change time t/sub 0/>1. In this paper we propose another more realistic criterion, establish a new simple recursive change detection/isolation algorithm and investigate its statistical properties. This algorithm can be recommended for on-line implementations.

关键词： Signal processing algorithms change detection algorithms H infinity control Probability Radar detection Sonar detection Aerospace control Aerospace industry Sonar navigation Radar signal processing

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Track loss and recovery for intermittently emitting targets

Track loss and recovery for intermittently emitting targets

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Simulation Winter Conference

作者： N.E. Rozen Cambridge Research Associates Washington D.C. DC USA

There is far less literature on passive sensor systems for tracking intermittently emitting targets than for tracking continuously emitting ones. A methodology for evaluating these systems via simulation is proposed, ... 详细信息

关键词： Target tracking Sensor systems Algorithm design and analysis Kinematics Virtual prototyping System testing Intelligent sensors Measurement errors Radio frequency change detection algorithms

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Designed inputs for detection and isolation of failures in the state transition matrices of dynamic systems

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IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY 1997年第2期5卷 149-162页

作者： Riggins, RN Ribbens, WB USAF INST TECHNOLDEPT ELECT & COMP ENGNWRIGHT PATTERSON AFBOH 45433 UNIV MICHIGAN DEPT ELECT ENGN & COMP SCIANN ARBORMI 48109

A new failure detection and isolation algorithm is presented for linear time-invariant deterministic systems, In particular, the technique exploits the system inputs to distinguish between a change in the state transition matrix and actuator failures, including output equivalent events, It is assumed that a failure has been detected previously by some other method, such as by a failure detection filter, Previous methods that attempted to isolate changes in the state transition matrix did not use the input in any way and required explicit knowledge of the changed parameter values (e.g., the multiple model method), The designed input method presented in this paper requires only the knowledge of the null spares of the changed parameter matrices, not of the explicit values of the changed parameters, This feature allows the failure detection and isolation (FDI) algorithm based on designed inputs to isolate partially unknown changes in the state transition matrix, a distinct advantage over other methods in terms of computational efficiency, Detailed design procedures are accompanied by an example that illustrates the input design method, The example uses designed inputs to distinguish between changes in the state transition parameters of an AFTI/F-16 model from nearly output equivalent actuator calibration errors.

关键词： Fault detection Control systems Design methodology Actuators Algorithm design and analysis Filters Isolation technology change detection algorithms Null space Computational efficiency

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A robust threshold retracking algorithm for measuring ice-sheet surface elevation change from satellite radar altimeters

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IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING 1997年第4期35卷 974-979页

作者： Davis, CH Department of Electrical and Computer Engineering University of Missouri Kansas City MO USA

A threshold retracking algorithm for processing ice-sheet altimeter data is presented. The primary purpose for developing this algorithm is detection of ice-sheet elevation change, where it is critical that a retracking algorithm produce repeatable elevations. The more consistent an algorithm is in selecting the retracking point the less likely that errors and/or biases will be introduced by the retracking scheme in the elevation-change measurement. We performed extensive comparisons between the threshold algorithm and two other widely used ice-sheet retracking algorithms on Geosat datasets comprised of over 60 000 crossover points. Our results show that the threshold retracking algorithm, with a 10% threshold level, produces ice-sheet surface elevations that are more repeatable than the elevations derived from the other retracking algorithms. For this reason, the threshold retracking algorithm has been adopted bg NASA/GSFC as an alternative to their existing algorithm for production of ice-sheet altimeter datasets under the NASA Pathfinder program. The threshold algorithm will be used to re-process existing ice-sheet altimeter datasets and to process the datasets from future altimeter missions.

关键词： Robustness Satellites change detection algorithms NASA Ice surface Spaceborne radar Monitoring Altimetry Cities and towns Surface waves

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