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991.
We develop a novel approach for computing the circle Hough transform entirely on graphics hardware (GPU). A primary role is assigned to vertex processors and the rasterizer, overshadowing the traditional foreground of pixel processors and enhancing parallel processing. Resources like the vertex cache or blending units are studied too, with our set of optimizations leading to extraordinary peak gain factors exceeding 358x over a typical CPU execution. Software optimizations, like the use of precomputed tables or gradient information and hardware improvements, like hyperthreading and multicores are explored on CPUs as well. Overall, the GPU exhibits better scalability and much greater parallel performance to become a solid alternative for computing the classical circle Hough transform versus those optimal methods run on emerging multicore architectures. 相似文献
992.
Ventura V 《Neural computation》2008,20(4):923-963
We propose a novel paradigm for spike train decoding, which avoids entirely spike sorting based on waveform measurements. This paradigm directly uses the spike train collected at recording electrodes from thresholding the bandpassed voltage signal. Our approach is a paradigm, not an algorithm, since it can be used with any of the current decoding algorithms, such as population vector or likelihood-based algorithms. Based on analytical results and an extensive simulation study, we show that our paradigm is comparable to, and sometimes more efficient than, the traditional approach based on well-isolated neurons and that it remains efficient even when all electrodes are severely corrupted by noise, a situation that would render spike sorting particularly difficult. Our paradigm will also save time and computational effort, both of which are crucially important for successful operation of real-time brain-machine interfaces. Indeed, in place of the lengthy spike-sorting task of the traditional approach, it involves an exact expectation EM algorithm that is fast enough that it could also be left to run during decoding to capture potential slow changes in the states of the neurons. 相似文献
993.
Brain reading using full brain support vector machines for object recognition: there is no "face" identification area 总被引:1,自引:0,他引:1
Over the past decade, object recognition work has confounded voxel response detection with potential voxel class identification. Consequently, the claim that there are areas of the brain that are necessary and sufficient for object identification cannot be resolved with existing associative methods (e.g., the general linear model) that are dominant in brain imaging methods. In order to explore this controversy we trained full brain (40,000 voxels) single TR (repetition time) classifiers on data from 10 subjects in two different recognition tasks on the most controversial classes of stimuli (house and face) and show 97.4% median out-of-sample (unseen TRs) generalization. This performance allowed us to reliably and uniquely assay the classifier's voxel diagnosticity in all individual subjects' brains. In this two-class case, there may be specific areas diagnostic for house stimuli (e.g., LO) or for face stimuli (e.g., STS); however, in contrast to the detection results common in this literature, neither the fusiform face area nor parahippocampal place area is shown to be uniquely diagnostic for faces or places, respectively. 相似文献
994.
This paper addresses the question: at the level of cortical cells present in the primary area V1, is the information sufficient to extract the local perspective from the texture? Starting from a model of complex cells in visual area V1, we propose a biologically plausible algorithm for frequency analysis applied to the shape from texture problem. First, specific log-normal filters are designed in replacement of the classical Gabor filters because of their theoretical properties and of their biological plausibility. These filters are separable in frequency and orientation and they better sample the image spectrum which makes them appropriate for any pattern analysis technique. A method to estimate the local frequency in the image, which discards the need to choose the best local scale, is designed. Based on this frequency analysis model, a local decomposition of the image into patches leads to the estimation of the local frequency variation which is used to solve the problem of recovering the shape from the texture. From the analytical relation between the local frequency and the geometrical parameters, under perspective projection, it is possible to recover the orientation and the shape of the original image. The accuracy of the method is evaluated and discussed on different kind of textures, both regular and irregular, with planar and curved surfaces and also on natural scenes and psychophysical stimuli. It compares favorably to the best existing methods, with in addition, a low computational cost. The biological plausibility of the model is finally discussed. 相似文献
995.
Detailed Real-Time Urban 3D Reconstruction from Video 总被引:2,自引:0,他引:2
M. Pollefeys D. Nistér J.-M. Frahm A. Akbarzadeh P. Mordohai B. Clipp C. Engels D. Gallup S.-J. Kim P. Merrell C. Salmi S. Sinha B. Talton L. Wang Q. Yang H. Stewénius R. Yang G. Welch H. Towles 《International Journal of Computer Vision》2008,78(2-3):143-167
The paper presents a system for automatic, geo-registered, real-time 3D reconstruction from video of urban scenes. The system
collects video streams, as well as GPS and inertia measurements in order to place the reconstructed models in geo-registered
coordinates. It is designed using current state of the art real-time modules for all processing steps. It employs commodity
graphics hardware and standard CPU’s to achieve real-time performance. We present the main considerations in designing the
system and the steps of the processing pipeline. Our system extends existing algorithms to meet the robustness and variability
necessary to operate out of the lab. To account for the large dynamic range of outdoor videos the processing pipeline estimates
global camera gain changes in the feature tracking stage and efficiently compensates for these in stereo estimation without
impacting the real-time performance. The required accuracy for many applications is achieved with a two-step stereo reconstruction
process exploiting the redundancy across frames. We show results on real video sequences comprising hundreds of thousands
of frames. 相似文献
996.
In this article we present a method for automatically recovering complete and dense depth maps of an indoor environment by
fusing incomplete data for the 3D environment modeling problem. The geometry of indoor environments is usually extracted by
acquiring a huge amount of range data and registering it. By acquiring a small set of intensity images and a very limited
amount of range data, the acquisition process is considerably simplified, saving time and energy consumption. In our method,
the intensity and partial range data are registered first by using an image-based registration algorithm. Then, the missing
geometric structures are inferred using a statistical learning method that integrates and analyzes the statistical relationships
between the visual data and the available depth on terms of small patches. Experiments on real-world data on a variety of
sampling strategies demonstrate the feasibility of our method.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
997.
Jan Rosell Carlos Vázquez Alexander Pérez Pedro Iñiguez 《Journal of Intelligent and Robotic Systems》2008,53(3):223-245
Haptic devices allow a user to feel either reaction forces from virtual interactions or reaction forces reflected from a remote
site during a bilateral teleoperation task. Also, guiding forces can be exerted to train the user in the performance of a
virtual task or to assist him/her to safely teleoperate a robot. The generation of guiding forces relies on the existence
of a motion plan that provides the direction to be followed to reach the goal from any free configuration of the configuration
space (-space). This paper proposes a method to obtain such a plan that interleaves a sampling-based exploration of -space with an efficient computation of harmonic functions. A deterministic sampling sequence (with a bias based on harmonic
function values) is used to obtain a hierarchical cell decomposition model of -space. A harmonic function is iteratively computed over the partially known model using a novel approach. The harmonic function
is the navigation function used as motion plan. The approach has been implemented in a planner (called the Kautham planner) that, given an initial and a goal configuration, provides: (a) a channel of cells connecting the cell that contains
the initial configuration with the cell that contains the goal configuration; (b) two harmonic functions over the whole -space, one that guides motions towards the channel and another that guides motions within the channel towards the goal; and
(c) a path computed over a roadmap built with the free samples of the channel. The harmonic functions and the solution path
are then used to generate the guiding forces for the haptic device. The planning approach is illustrated with examples on
2D and 3D workspaces.
This work was partially supported by the CICYT projects DPI2005-00112 and DPI2007-63665. 相似文献
998.
Behaviour based on decision matrices for a coordination between agents in a urban traffic simulation
René Mandiau Alexis Champion Jean-Michel Auberlet Stéphane Espié Christophe Kolski 《Applied Intelligence》2008,28(2):121-138
This paper describes a multi-agent coordination mechanism applied to intersection simulation situations. In a goal of urban
traffic simulation, we must consider the dynamic interactions between autonomous vehicles. The field of multi-agent systems
provides us some studies for such systems, in particular on the coordination mechanisms. Conflicts between vehicles (i.e.
agents) are very frequent in such applications, and they may cause deadlocks, particularly at intersections such as crossroads.
Our approach is based on the solving of two player games/decision matrices which characterize three basic situations. An aggregation
method generalizes to n-player games for complex crossroads. The objective of this approach consists in searching basic two-player
matrices for solving n-agent problems. To explain the principle, we describe our approach for a particular case of crossroad
with three agents. Finally, the obtained results have been examined via a tool of road traffic simulation, ARCHISIM. We assume
also that the global traffic replicates the behavior of agents in different situations. 相似文献
999.
This paper addresses the problem of fault detection and isolation for a particular class of discrete event dynamical systems
called hierarchical finite state machines (HFSMs). A new version of the property of diagnosability for discrete event systems
tailored to HFSMs is introduced. This notion, called L1-diagnosability, captures the possibility of detecting an unobservable fault event using only high level observations of the
behavior of an HFSM. Algorithms for testing L1-diagnosability are presented. In addition, new methodologies are presented for studying the diagnosability properties of
HFSMs that are not L1-diagnosable. These methodologies avoid the complete expansion of an HFSM into its corresponding flat automaton by focusing
the expansion on problematic indeterminate cycles only in the associated extended diagnoser.
Andrea Paoli received the master degree in Computer Science Engineering and the Ph.D. in Automatic Control and Operational Research from the University of Bologna in 2000 and 2003 respectively. He currently holds a Post Doc position at the Department of Electronics, Computer Science and Systems (DEIS) at the University of Bologna, Italy. He is a member of the Center for Research on Complex Automated Systems (CASY) Giuseppe Evangelisti. From August to January 2002, and in March 2005 he held visiting positions at the Department of Electrical Engineering and Computer Science at The University of Michigan, Ann Arbor. In July 2005 he won the prize IFAC Outstanding AUTOMATICA application paper award for years 2002-2005 for the article by Claudio Bonivento, Alberto Isidori, Lorenzo Marconi, Andrea Paoli titled Implicit fault-tolerant control: application to induction motors appeared on AUTOMATICA issue 30(4). Since 2006 he is a member of the IFAC Technical Committee on Fault Detection, Supervision and Safety of Technical Processes (IFAC SAFEPROCESS TC). His current research interests focus on Fault Tolerant Control and Fault Diagnosis in distributed systems and in discrete event systems and on industrial automation software architectures following an agent based approach. His theoretical background includes also nonlinear control and output regulation using geometric approach. Stéphane Lafortune received the B. Eng degree from Ecole Polytechnique de Montréal in 1980, the M. Eng. degree from McGill University in 1982, and the Ph.D. degree from the University of California at Berkeley in 1986, all in electrical engineering. Since September 1986, he has been with the University of Michigan, Ann Arbor, where he is a Professor of Electrical Engineering and Computer Science. Dr. Lafortune is a Fellow of the IEEE (1999). He received the Presidential Young Investigator Award from the National Science Foundation in 1990 and the George S. Axelby Outstanding Paper Award from the Control Systems Society of the IEEE in 1994 (for a paper co-authored with S. L. Chung and F. Lin) and in 2001 (for a paper co-authored with G. Barrett). At the University of Michigan, he received the EECS Department Research Excellence Award in 1994–1995, the EECS Department Teaching Excellence Award in 1997–1998, and the EECS Outstanding Achievement Award in 2003–2004. Dr. Lafortune is a member of the editorial boards of the Journal of Discrete Event Dynamic Systems: Theory and Applications and of the International Journal of Control. His research interests are in discrete event systems modeling, diagnosis, control, and optimization. He is co-developer of the software packages DESUMA and UMDES. He co-authored, with C. Cassandras, the textbook Introduction to Discrete Event Systems—Second Edition (Springer, 2007). Recent publications and software tools are available at the Web site . 相似文献
Stéphane LafortuneEmail: |
Andrea Paoli received the master degree in Computer Science Engineering and the Ph.D. in Automatic Control and Operational Research from the University of Bologna in 2000 and 2003 respectively. He currently holds a Post Doc position at the Department of Electronics, Computer Science and Systems (DEIS) at the University of Bologna, Italy. He is a member of the Center for Research on Complex Automated Systems (CASY) Giuseppe Evangelisti. From August to January 2002, and in March 2005 he held visiting positions at the Department of Electrical Engineering and Computer Science at The University of Michigan, Ann Arbor. In July 2005 he won the prize IFAC Outstanding AUTOMATICA application paper award for years 2002-2005 for the article by Claudio Bonivento, Alberto Isidori, Lorenzo Marconi, Andrea Paoli titled Implicit fault-tolerant control: application to induction motors appeared on AUTOMATICA issue 30(4). Since 2006 he is a member of the IFAC Technical Committee on Fault Detection, Supervision and Safety of Technical Processes (IFAC SAFEPROCESS TC). His current research interests focus on Fault Tolerant Control and Fault Diagnosis in distributed systems and in discrete event systems and on industrial automation software architectures following an agent based approach. His theoretical background includes also nonlinear control and output regulation using geometric approach. Stéphane Lafortune received the B. Eng degree from Ecole Polytechnique de Montréal in 1980, the M. Eng. degree from McGill University in 1982, and the Ph.D. degree from the University of California at Berkeley in 1986, all in electrical engineering. Since September 1986, he has been with the University of Michigan, Ann Arbor, where he is a Professor of Electrical Engineering and Computer Science. Dr. Lafortune is a Fellow of the IEEE (1999). He received the Presidential Young Investigator Award from the National Science Foundation in 1990 and the George S. Axelby Outstanding Paper Award from the Control Systems Society of the IEEE in 1994 (for a paper co-authored with S. L. Chung and F. Lin) and in 2001 (for a paper co-authored with G. Barrett). At the University of Michigan, he received the EECS Department Research Excellence Award in 1994–1995, the EECS Department Teaching Excellence Award in 1997–1998, and the EECS Outstanding Achievement Award in 2003–2004. Dr. Lafortune is a member of the editorial boards of the Journal of Discrete Event Dynamic Systems: Theory and Applications and of the International Journal of Control. His research interests are in discrete event systems modeling, diagnosis, control, and optimization. He is co-developer of the software packages DESUMA and UMDES. He co-authored, with C. Cassandras, the textbook Introduction to Discrete Event Systems—Second Edition (Springer, 2007). Recent publications and software tools are available at the Web site . 相似文献
1000.
Lionel Buchaillot Olivier Millet Emmanuel Quévy Dominique Collard 《Microsystem Technologies》2008,14(1):69-78
The paper presents the snap-through phenomenon in the case of micro fabricated clamped-clamped buckled beam. This dynamic
post-buckling behavior is likely to occur in 3D microstructures when they are subjected to large vibration amplitudes. The
main difference between this work and previous studies is the MEMS specific beam dimension, especially the large initial deflection
of the buckled beam that involves the inversion of the two first resonance frequencies. The mathematical development allows
showing how the vibration amplitude of the supporting base affects the post-buckling dynamic behavior of the beam. For each
frequency, the limit between the stable behavior and the snap-through behavior is evaluated. Moreover, the effect of environment
is taken into account from the damping point of view. Samples are fabricated and the experiment is described. Measurements
are compared to the theoretical approach and the results are in good agreement with the proposed model. 相似文献