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Discrimination with spike times and ISI distributions

NEURAL COMPUTATION 2008年第6期20卷 1411-1426页

作者： Kang, Kukiin Amari, Shun-Ichi RIKEN BSI Wako Saitama 3510198 Japan

We study the discrimination capability of spike time sequences using the Chernoff distance as a metric. We assume that spike sequences are generated by renewal processes and study how the Chernoff distance depends on the shape of interspike interval (ISI) distribution. First, we consider a lower bound to the Chernoff distance because it has a simple closed form. Then we consider specific models of ISI distributions such as the gamma, inverse gaussian (IG), exponential with refractory period (ER), and that of the leaky integrate-and-fire (LIF) neuron. We found that the discrimination capability of spike times strongly depends on high-order moments of ISI and that it is higher when the spike time sequence has a larger skewness and a smaller kurtosis. High variability in terms of coefficient of variation (CV) does not necessarily mean that the spike times have less discrimination capability. Spike sequences generated by the gamma distribution have the minimum discrimination capability for a given mean and variance of ISI. We used series expansions to calculate the mean and variance of ISIs for LIF neurons as a function of the mean input level and the input noise variance. Spike sequences from an LIF neuron are more capable of discrimination than those of IG and gamma distributions when the stationary voltage level is close to the neuron's threshold value of the neuron.

关键词： computer algorithms TIME-series analysis INTERVAL analysis (Mathematics) MATHEMATICAL statistics PROBABILITIES ARTIFICIAL intelligence

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Competitive interactions between felid species may limit the southern distribution of bobcats Lynx rufus

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ECOGRAPHY 2008年第6期31卷 757-764页

作者： Sanchez-Cordero, Victor Stockwell, David Sarkar, Sahotra Liu, Hawoei Stephens, Christopher R. Gimenez, Joaquin Univ Nacl Autonoma Mexico Inst Biol Dept Zool Mexico City 04510 DF Mexico Univ Calif San Diego San Diego Super Comp Ctr La Jolla CA 92093 USA Univ Texas Austin Sect Integrat Biol Austin TX 78712 USA Univ Nacl Autonoma Mexico Inst Ciencias Nucl Mexico City 04510 DF Mexico

Bobcats are opportunistic felids occurring in a diverse range of habitats and with a widespread distribution from southern Canada to southern Mexico. To explore why the bobcat's distribution stops at the Isthmus of Tehuantepec, we modelled the ecological niches, projected as potential distributions, of the felid community (bobcat Lynx rufus, puma Puma concolor, jaguar Panthera onca, margay Leopardus wiedii, jaguarundi Herpailurus yagouaroundi, and ocelot Leopardus pardalis) in southern Mexico, using occurrence data, environmental maps, the computer algorithm GARP, and a GIS platform. The resulting geographical projection of the ecological niche of bobcats extends south of the Isthmus of Tehuantepec, suggesting that ecological conditions exist for the establishment of populations. The overlap of the modelled distribution of the bobcat was large with that of the puma (97%), but low with that of the ocelot (44%), margay (46%), jaguar (49%), and jaguarundi (52%), the latter three having relatively similar size and feeding habits to bobcats. Moreover, an independent analysis computing a geographic co-occurrence index showed a similar trend of geographic avoidance (values <-4.60 showing a statistically significant anti-correlation) between bobcats with the margay, ocelot, jaguarundi, and jaguar, but not with the puma (values > 0.15), while all felids, except bobcats, showed a geographic co-occurrence in southern Mexico (values ranging from -1.91 to 4.71). The Isthmus of Tehuantepec, a lowland region with subtropical habitat, is unlikely to serve as a geographic and ecological barrier to bobcats. As mammal inventories have been conducted for over a century in this region with no records of bobcats, it is unlikely that bobcats are present but have just not been seen. Fossil records also provide no support for the presence of bobcats in that region in the past. Thus, competitive interactions with other felid species appear important in limiting the southern distribution of b

关键词： ENVIRONMENTAL mapping ANIMAL nutrition computer algorithms ANIMALS -- Population biology HABITAT (Ecology) ANIMAL dispersal BOBCAT

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Use IFDs to develop and showcase your design concepts

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Electronic Design 2008年第20期56卷 42-43页

作者： Woodward, W. Stephen University of North Carolina Chapel Hill

W. Stephen Woodward, Electronic Design's most prolific contributor, has suggested the significance of using Ideas for Design (IFD) for developing and exhibiting design concepts. IFDs play a vital role in presenting and developing new circuit design ideas and themes to the engineering community. The Take Back Half (TBH) method takes deliberate advantage of the equality of straight-integration's undamped over/undershoots. Experience gained from applying TBH reveals that the algorithm's stability is robust, while simulation and experimentation agree that convergence can always be achieved while steady-state error remains equal to zero. Among the techniques for measuring airspeed, thermal anemometry has the virtues of simplicity and easy miniaturization, while it also needs some provision for measurement linearization. The classic diode-capacitor charge pump also is one of the many starting points for voltage-to-frequency converter designs.

关键词： ENGINEERING design PUBLISHERS & publishing computer programming computer algorithms MATHEMATICAL programming ELECTRONIC circuits INTERFACE circuits INTEGRATED circuits computer interfaces

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Toward consistent use of reporting scales in imaging studies

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ACADEMIC RADIOLOGY 2008年第2期15卷 137-138页

作者： Wagner, Robert F. US FDA Off & Engn Labs Ctr Devices & Radiol Hlth Silver Spring MD 20993 USA

This editorial refers to the article \"Potential effect of different radiologist reporting methods on studies showing benefit of CAD\" by Horsch et al in the present issue of Academic Radiology (1).There are several communities or \"cultures\" that will find common ground in this article. One community includes the public and private funding sponsors and developers of new technologies for medical imaging-in particular, the technology of computer algorithms that assist radiologists in their decision making. Another community therefore is that of the radiologists themselves who will use these technologies. Then there is the community developing study designs and statistical assessment methodologies for evaluating the new technologies. Downstream we encounter the community of public policy makers who approve and clear these technologies for entrance to the marketplace for their specified task and the third-party payers who determine when a combination of a technology and a diagnostic task meet their criteria for reimbursement.

关键词： Data Interpretation Statistical Diagnosis computer-Assisted Diagnostic Imaging 数据说明统计诊断计算机辅助诊断显像文献工作病案系统计算机化 diagnostic imaging Representation of data Policy Makers Diagnosis Inventions computer-assisted Third-Party Payers reporting Radiologists Data interpretation new technology computer algorithms

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Effective cluster-based seed design for cross-species sequence comparisons

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BIOINFORMATICS 2008年第24期24卷 2926-2927页

作者： Zhou, Leming Mihai, Ingrid Florea, Liliana George Washington Univ Dept Comp Sci Washington DC 20052 USA

To annotate newly sequenced organisms, cross-species sequence comparison algorithms can be applied to align gene sequences to the genome of a related species. To improve the accuracy of alignment, spaced seeds must be optimized for each comparison. As the number and diversity of genomes increase, an efficient alternative is to cluster pairwise comparisons into groups and identify seeds for groups instead of individual comparisons. Here we investigate a measure of comparison closeness and identify classes of comparisons that show similar seed behavior and therefore can employ the same seed.

关键词： NUCLEOTIDE sequence GENOMES ONLINE databases computer algorithms BIODIVERSITY BIOINFORMATICS

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ALGORITHM FOR TEMPERATURE CONTROL IN THE SKUNK CABBAGE, SYMPLOCARPUS FOETIDUS

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BIOTECHNOLOGY & BIOTECHNOLOGICAL EQUIPMENT 2008年第4期22卷 959-963页

作者： Takahashi, K. Ito, T. Endo, T. Chiba, S. Ito, K. Osada, H. Iwate Univ Fac Engn Dept Elect & Elect Engn Morioka Iwate 020 Japan Daisho Denshi Co Ltd Meguro Ku Tokyo Japan Honda Motor Co Ltd Minato Ku Tokyo Japan Iwate Univ Fac Agr Cryobiofrontier Res Ctr Morioka Iwate 020 Japan

This Paper presents a temperature control algorithm for the skunk of the skunk cabbage Symplocarpus foetidus, a plant which holds its spadix temperature nearly constant. We derive the control algorithm from a proposed thermoregulation model of the spadix of S. foetidus. In addition, we investigate the control algorithm of *** for general industrial applications from a control engineering perspective by running simulations and applying it to actual equipment. The temperature control algorithm responds to the rate of change of the controlled variable over time and adjusts the output of the controller as required to minimize the rate of change. The control algorithm of the spadix of *** is robust to perturbations in the controlled object and the Control algorithm incorporated into a microprocessor successfully controls the performance actual equipment.

关键词： output controller Symplocarpus Industrial applications spadix controlled object Temperature control algorithms control variable Cabbage change rate computer algorithms

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The simulation of material behaviors in friction stir welding process by using rate-dependent constitutive model

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JOURNAL OF MATERIALS SCIENCE 2008年第1期43卷 222-232页

作者： Zhang, Z. Chen, J. T. Dalian Univ Technol Dept Engn Mech State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China

Friction stir welding is a new solid state joining technology, which is suitable for joining some hard-to-weld materials, such as aluminum alloy, magnesium alloy, etc. The modeling of material flows can provide an efficient method for the investigation on the mechanism of friction stir welding. So, 3D material flows under different process parameters in the FSW process of 1018 steel are studied by using rate-dependent constitutive model. Numerical results indicate that the border of the shoulder can affect the material flow near the shoulder-plate interface. The mixture of the material in the lower half of the friction stir weld can benefit from the increase in the angular velocity or the decrease in the welding speed. But flaws may occur when the angular velocity is very high or the translational velocity is very small. When the angular velocity applied on the pin is small or the welding speed is high, the role of the extrusion of pin on transport of the material in FSW becomes more important. Swirl or vortex occurs in the tangent material flow and may be easier to be observed with the increase in the angular velocity of the pin.

关键词： WELDING computer simulation THREE-dimensional imaging MATERIALS science SPEED TEMPERATURE STRAINS & stresses (Mechanics) computer algorithms MATERIALS -- Dynamic testing

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Mining Massive Data Sets for Security : Advances in Data Mining, Search, Social Networks and Text Mining, and Their Applications to Security

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丛书名： NATO Science for Peace and Security Series. D, Information and Communication Security, vol. 19

2008年

作者： Fogelman-Soulié, Françoise North Atlantic Treaty Organization

Published in cooperation with NATO Public Diplomacy Division.

ISBN: (纸本)9781586038984;9781441605399

Published in cooperation with NATO Public Diplomacy Division.

关键词： Terrorism--Prevention Terrorism--Risk assessment Data mining computer algorithms

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Torque and Reactive Power Control of Doubly-Fed Induction Machine with Matrix Converter

Torque and Reactive Power Control of Doubly-Fed Induction Ma...

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IEEE International Symposium on Industrial Electronics

作者： Shapoval, Ivan Peresada, Sergei Asher, Greg Clare, Jon Natl Acad Sci Ukraine Inst Electrodynam Kiev Ukraine Natl Acad Sci Ukraine Dept Elect Engn Kiev Ukraine Univ Nottingham Sch Elect & Elect Engn Nottingham NG7 2RD England

ISBN: (纸本)9781424416653

Asymptotic torque-reactive power vector control algorithm based on full doubly-fed induction machine model is designed and investigated. Full-scale experimental testing of the doubly-fed induction machine control algorithms with matrix converter at rotor side is performed. Doubly-fed induction machine control algorithm has been implemented in real time using DSP-controller and successfully tested on the experimental rig.

关键词： Induction machines doubly-fed matrix converters Reactive power control Torque computer algorithms

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STATE PARAMETERS INTERCONNECTIONS OF POWER SYSTEM INCLUDING A HIGH FREQUENCY SYNCHRONOUS GENERATOR WITH AN ASYNCHONOUS TIE

STATE PARAMETERS INTERCONNECTIONS OF POWER SYSTEM INCLUDING ...

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International Conference on Modern Technique and Technologies

作者： Filyaev, K. S Urals State Univ Chelyabinsk Russia

ISBN: (纸本)9781424416097

The last progresses in power mechanical engineering and power electronics had permitted to construct gas turbine power units (GTPU) with high frequency synchronous generators (HFSG) and static frequency converters (SFC) operating as asynchronous tie (AT). Such GTPU has a number of advantages over conventional one: 1) does not have a reduction gear between turbine and generator shafts; 2) gives an opportunity to minimize weight and dimensions of a turboset and power plant as a whole; 3) permits to optimize turbine's modes by means of it's rotation speed control; 4) gives additional opportunities of GTPU states control and required power quality support with the help of SFC control; 5) owing to this control, allows to improve operating speed of states control and the unit protection. These features make AT GTPUs of great practical interest, so that a considerable number of power stations with such units is planned to put into operation in Russia in the nearest future. Mention that they are designed to operate both in parallel with the power system and autonomous supplying a local load. The most attractive field of AT GTPU's application is power supply of distant regions and areas difficult of access. So the new electrotechnical complex appears: GTPU with HFSG and AT - centralized power system (CPS) - local load (LL) (fig. 1). The AT GTPUs' appearance poses a number of standard and specific problems concerning projection, putting into operation and maintenance of the complex. In this situation at the absence of a sufficient argumentation of how the AT should be arranged the following problem was posed and solved: to determine the interconnections between the complex's state parameters (CSPs) by presenting SFC as AT. It is expedient to find the interconnections in an analytical form (formulas) so far as digital (or numerical) models being realized in specialized programs (Simulink, PSCAD, etc.) are not clear and universal enough for many problems such as the complex's s

关键词： power systems reduction gear Power Plants state parameter Tie dynamos turbines Operating speed partial load High frequency Standing Orders computer algorithms Power electronics

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