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Computation of nonequilibrium high-temperature axisymmetric boundary-layer flows

JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER 2002年第4期16卷 490-497页

作者： Barbante, PF Degrez, G Sarma, GSR Von Karman Inst Fluid Dynam B-1640 Rhode St Genese Belgium Deutsch Zentrum Luft & Raumfahrt D-37073 Gottingen Germany Free Univ Brussels B-1050 Brussels Belgium

Efficient and accurate Hermitian-type multipoint finite difference methods are used to develop a general boundary-layer code for analyzing reacting flows around bodies of revolution. The main motivation is to build a reliable code that can be used for the investigation of the influence of different physico-chemical models for transport properties, chemical kinetics, and finite rate wall catalysis on practically relevant quantities like heat flux and skin friction at the body surface. Special care has been devoted to the correct modeling of diffusion fluxes, an aspect that is often neglected in literature. The exact Stefan-Maxwell equations are used to model the diffusion fluxes and are solved with an efficient iterative technique. Finite rate catalysis is an important aspect of thermal protection system (TPS) materials studies, for which a boundary-layer code is a very useful tool because it allows the computation of the heat flux at a cost that is a fraction of a Navier-Stokes approach. Wall catalyticity effects are taken into account by means of a model that allows one to express a suitable set of wall reactions with the associated reaction-rate probabilities. Computations performed on a variety of problems and the results shown here on some typical test cases indicate the ability and reliability of the code to cope with a wide range of nonequilibrium conditions, making it a potentially useful tool for physico-chemical and TPS material studies.

关键词： Nonequilibrium Codes CASING INSPECTION Skin friction transaction processing system nonequilibrium conditions diffusion flux wall Body Surface AXISYMMETRIC hierarchical coding transport properties Heat flux

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Performance evaluation of cell discarding mechanisms for the distribution of VBR MPEG-2 video over ATM networks

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IEEE TRANSACTIONS ON BROADCASTING 1998年第2期44卷 206-215页

作者： Cuenca, P Garrido, A Quiles, F Orozco-Barbosa, L Univ Castilla La Mancha Dept Informat Albacete 02071 Spain Univ Ottawa Sch Informat Technol & Engn Ottawa ON K1N 6N5 Canada

ATM networks promise to provide the means to support a wide range of applications exhibiting different traffic characteristics and performance requirements. Video communications have been recognized as one of the most demanding applications to be supported by ATM networks. This is mainly due to the need of transferring large amounts of darn and the strict timing requirements characterizing digital video applications. In this paper, simulation experiments are conducted to study the performance of the different cell discarding control mechanisms, in terms of quality of service, when used in an ATM network supporting hierarchical encoded VBR MPEG-2 video distribution. Our results show the effectiveness of the control schemes in reducing the cell loss rates as compared to the system configuration without no cell discarding scheme in place.

关键词： hierarchical coding video compressed traffic QoS and priority queueing

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Application level framing applied to image compression

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ANNALES DES TELECOMMUNICATIONS-ANNALS OF TELECOMMUNICATIONS 2002年第5-6期57卷 502-519页

作者： Iren, S Amer, PD Marconi Plc Warrendale PA 15086 USA Univ Delaware Dept Comp & Informat Sci Newark DE 19716 USA

Two well-known wavelet zerotree encoding algorithms, Embedded Zerotree Encoding (EZW) and Set Partitioning in hierarchical Trees (SPIHT), provide excellent progressive display when images are transmitted over reliable networks. However, both algorithms are state-dependent and can perform poor;y over unreliable networks. We apply the concept of network-conscious image compression to the SPIHT wavelet zerotree encoding algorithm, to improve its performance over unreliable networks. Experimental results confirm the utility of network-conscious image compression concept.

关键词： image compression hierarchical coding image coding wavelet expansion transmission error system robustness packet transmission lossy system

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Segmentation of video sequences for partition tree generation

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ANNALS OF TELECOMMUNICATIONS 1997年第7-8期52卷 388-396页

作者： Pardas, M Salembier, P pc Barcelona Espagne

In this paper we propose a segmentation structure to generate a partition tree with multiple partition proposals. These multiple partitions are obtained for every image in a hierarchical way, front the coarsest one to the finest one, Time evolution of the regions is defined through a projection step which relates the previous coded partition with the current partition tree, Finer partitions than the projected one are defined segmenting the projected partition using texture criteria, while coarser partitions are obtained merging regions with motion criteria. Morphological tools are used both in the projection and the re-segmentation steps.

关键词： image processing moving image segmentation hierarchical coding mathematical morphology

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Time course of visual perception:: Coarse-to-fine processing and beyond

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PROGRESS IN NEUROBIOLOGY 2008年第4期84卷 405-439页

作者： Hegde, Jay Univ Minnesota Dept Psychol Minneapolis MN 55455 USA

Our perception of a visual scene changes rapidly in time, even when the scene itself does not. It is increasingly clear that understanding how the visual percept changes in time is crucial to understanding how we see. We are still far from fully understanding the temporal changes in the visual percept and the neural mechanisms that underlie it. But recently, many disparate lines of evidence are beginning to converge to produce a complex but fuzzy picture of visual temporal dynamics. It is clear, largely from psychophysical studies in humans, that one can get the 'gist' of complex visual scenes within about 150 ms after the stimulus onset, even when the stimulus itself is presented as briefly as 10 ms or so. It generally takes longer processing, if not longer stimulus presentation, to identify individual objects. It may take even longer for a fuller semantic understanding, or awareness, of the scene to emerge and be encoded in short-term memory. Microelectrode recording studies in monkeys, along with neuroimaging studies mostly in humans, have elucidated many important temporal dynamic phenomena at the level of individual neurons and neuronal populations. Many of the temporal changes at the perceptual and the neural levels can be captured by the multifaceted and somewhat ambiguous concept of coarse-to-fine processing, although it is clear that not all temporal changes can be characterized this way. A more comprehensive, albeit unproven, alternative framework for understanding visual temporal dynamics is to view it as a sequential, Bayesian decision-making process. At each step, the visual system infers the likely nature visual scene by jointly evaluating the available processed image information and prior knowledge about the scene, including prior inferences. Whether the processing proceeds in a coarse-to-fine fashion depends largely on whether the underlying computations are hierarchical or not. Characterizing these inferential steps from the computational, perceptu

关键词： adaptive filtering awareness Bayesian inference decorrelation fine-to-coarse feedback feed-forward global-to-local hierarchical coding hypothesis testing lateralization masking microgenesis natural vision perceptual learning plasticity priming recurrent/reentrant processing sequential decision-making

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Neural basis of hierarchical visual form processing of Japanese Kanji characters

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BRAIN AND BEHAVIOR 2015年第12期5卷 e00413-e00413页

作者： Higuchi, Hiroki Moriguchi, Yoshiya Murakami, Hiroki Katsunuma, Ruri Mishima, Kazuo Uno, Akira Univ Tsukuba Grad Sch Comprehens Human Sci Tsukuba Ibaraki 3058577 Japan Japan Soc Promot Sci Chiyoda Ku Tokyo 1020083 Japan Natl Ctr Neurol & Psychiat Natl Inst Mental Hlth Dept Psychophysiol Kodaira Tokyo 1870031 Japan Natl Ctr Neurol & Psychiat Integrat Brain Imaging Ctr Kodaira Tokyo 1870031 Japan Nagoya Univ Dept Psychol Chikusa Ku Nagoya Aichi 4648601 Japan Univ Tsukuba Fac Human Sci Tsukuba Ibaraki 3058577 Japan

Introduction: We investigated the neural processing of reading Japanese Kanji characters, which involves unique hierarchical visual processing, including the recognition of visual components specific to Kanji, such as radicals. Methods: We performed functional MRI to measure brain activity in response to hierarchical visual stimuli containing (1) real Kanji characters (complete structure with semantic information), (2) pseudo Kanji characters (subcomponents without complete character structure), (3) artificial characters (character fragments), and (4) checkerboard (simple photic stimuli). Results: As we expected, the peaks of the activation in response to different stimulus types were aligned within the left occipitotemporal visual region along the posterior-anterior axis in order of the structural complexity of the stimuli, from fragments (3) to complete characters (1). Moreover, only the real Kanji characters produced functional connectivity between the left inferotemporal area and the language area (left inferior frontal triangularis), while pseudo Kanji characters induced connectivity between the left inferotemporal area and the bilateral cerebellum and left putamen. Conclusions: Visual processing of Japanese Kanji takes place in the left occipitotemporal cortex, with a clear hierarchy within the region such that the neural activation differentiates the elements in Kanji characters' fragments, subcomponents, and semantics, with different patterns of connectivity to remote regions among the elements.

关键词： hierarchical coding Japanese logographic Kanji Kanji radical Left occipitotemporal cortex visual character form

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Emergence of invariant representation of vocalizations in the auditory cortex

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JOURNAL OF NEUROPHYSIOLOGY 2015年第5期114卷 2726-2740页

作者： Carruthers, Isaac M. Laplagne, Diego A. Jaegle, Andrew Briguglio, John J. Mwilambwe-Tshilobo, Laetitia Natan, Ryan G. Geffen, Maria N. Univ Penn Dept Otorhinolaryngol & Head & Neck Surg Philadelphia PA 19104 USA Univ Penn Grad Grp Phys Philadelphia PA 19104 USA Univ Fed Rio Grande do Norte Brain Inst BR-59072970 Natal RN Brazil Univ Penn Grad Grp Neurosci Philadelphia PA 19104 USA

An essential task of the auditory system is to discriminate between different communication signals, such as vocalizations. In everyday acoustic environments, the auditory system needs to be capable of performing the discrimination under different acoustic distortions of vocalizations. To achieve this, the auditory system is thought to build a representation of vocalizations that is invariant to their basic acoustic transformations. The mechanism by which neuronal populations create such an invariant representation within the auditory cortex is only beginning to be understood. We recorded the responses of populations of neurons in the primary and nonprimary auditory cortex of rats to original and acoustically distorted vocalizations. We found that populations of neurons in the nonprimary auditory cortex exhibited greater invariance in encoding vocalizations over acoustic transformations than neuronal populations in the primary auditory cortex. These findings are consistent with the hypothesis that invariant representations are created gradually through hierarchical transformation within the auditory pathway.

关键词： auditory cortex hierarchical coding invariance processing vocalizations

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Replacement of the "genetic program" program

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BIOLOGY & PHILOSOPHY 2014年第1期29卷 33-53页

作者： Planer, Ronald J. Rutgers State Univ Dept Philosophy Ctr Cognit Sci New Brunswick NJ 08901 USA

Talk of a "genetic program" has become almost as common in cell and evolutionary biology as talk of "genetic information". But what is a genetic program? I understand the claim that an organism's genome contains a program to mean that its genes not only carry information about which proteins to make, but also about the conditions in which to make them. I argue that the program description, while accurate in some respects, is ultimately misleading and should be abandoned. After that, I sketch an alternative framework which is better suited to capturing the full informational nature of genes. This framework is centered on the notion of a signaling game, as originally developed by David Lewis, but expanded upon considerably by Brian Skyrms in more recent years. On the view I develop, genes turn out to be the producers and consumers of regulatory or developmental information, rather than entities encoding such information. This finding has consequences that link up with a broader debate in the philosophy of biology concerning inheritance systems. I take this to be one form of theoretical payoff that results from applying the signaling games framework to genes.

关键词： Genetic program Gene promoters hierarchical coding Information processing Signaling games

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Preliminary Research of a Medical Sensor Design by Evolution

Preliminary Research of a Medical Sensor Design by Evolution

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International Seminar on Future Information Technology and Management Engineering

作者： Song, Xuekun Yang, Zhansheng Zhao, Jinchuang HeNan Univ TCM Inst Informat Technol Zhengzhou 450000 Henan Peoples R China China Unicom Co Ltd Henan Branch Co Zhengzhou 450000 Peoples R China Guangxi Univ Coll Comp Elect & Informat Nanning 530004 Peoples R China

ISBN: (纸本)9780769534800

Combining computer technology with traditional Chinese medical treatment mechanisms, the paper deals with a new approch to the design of medical sensor, designs the main circuit of an EMG sensor by evolution. A framework of evolvable sensor is proposed based on the combining of the characteristics of conventional sensor and evolvable *** with the hierarchical coding characteristic of GA and analog/digital circuit, hierarchical structures evolve method which suits the evolvement of analog sensor circuit is proposed. In the present case study low pass filter circuits are evolved successfully in the usage of an improved elitist preserving and adaptive GA through off-line evolution, what more, simulated by OrCAD/Pspice. The preliminary experiments and results attempt the meaningful explore to the entire design of the evolvable sensor and the transform from EHW theory based on analog circuit to practical application.

关键词： evolvable hardware evolvable sensor genetic algorithm medical sensor evolvable hardware Genetic Algorithm (GA) major loop analog circuits Computer technology Sensors analog sensor hierarchical coding

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AN EFFICIENT IMAGE COMPRESSION ALGORITHM WITHOUT DISTORTION

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PATTERN RECOGNITION LETTERS 1991年第2期12卷 69-72页

作者： HUANG, L BIJAOUI, A Observatoire de la Côte d'Azur. Dep. A. Fresnel. URA 1361 CNRS. B.P. 139 F-06003 Nice Cedex France

We present in this paper an efficient image compression algorithm without distortion. It is based on a special iterative central prediction method with a hierarchic 4-bit code. By applying this method to some hydrodyn... 详细信息

关键词： IMAGE DATA COMPRESSION CENTRAL PREDICTION METHOD hierarchical coding

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