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Two-point probability distribution function analysis of Co-polymer nano-composites

INTERNATIONAL JOURNAL OF PLASTICITY 2005年第1期21卷 185-198页

作者： Jefferson, G Garmestani, H Tannenbaum, R Gokhale, A Tadd, E Georgia Inst Technol Atlanta GA 30332 USA FSU FAMU COE Tallahassee FL USA

Empirical forms of the two-point probability functions for two-phase composites are investigated and alternate forms are introduced which can incorporate both periodicity and randomness. Microstructures of Co-polymer nano-composites have been analyzed and it was discovered that the material did not exhibit randomness and present empirical formulations may not be appropriate for its representation. A modified form of the probability function is introduced that can provide a tool to examine the degree of randomness and periodicity. The results show the potential of these functions in the evaluation of microstructures and acquiring higher order details not available previously. (C) 2004 Elsevier Ltd. All rights reserved.

关键词： microstructure statistical mechanics probability functions

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A first passage time distribution for a discrete version of the Ornstein-Uhlenbeck process

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JOURNAL OF PHYSICS A-MATHEMATICAL AND GENERAL 2004年第12期37卷 3759-3767页

作者： Larralde, H Univ Nacl Autonoma Mexico Ctr Ciencias Fis Cuernavaca 62251 Morelos Mexico

The probability of the first entrance to the negative semi-axis for a one-dimensional discrete Ornstein-Uhlenbeck (O-U) process is studied in this work. The discrete O-U process is a simple generalization of the random walk and many of its statistics may be calculated using essentially the same formalism. In particular, the case in which Sparre-Andersen's theorem applies for normal random walks is considered, and it is shown that the universal features of the first passage probability do not extend to the discrete O-U process. Finally, an explicit expression for the generating function of the probability of first entrance to the negative real axis at step n is calculated and analysed for a particular choice of the step distribution.

关键词： Generating functions discrete element probability functions semi-axis PASSAGE real axis Ornstein-Uhlenbeck process entry Random walk timing channel Umklapp process

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Some basic questions in the treatment of intercomparison data

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MEASUREMENT TECHNIQUES 2003年第4期46卷 421-426页

作者： Ciarlini, P Pavese, F CNR Ist Applicaz Calcolo M Picone Rome Italy CNR Ist Metrol G Colonnetti I-10126 Turin Italy

An analysis of the interlaboratory comparison process highlights the need to pose some basic questions that should be answered before the exercises take place. They often remain hidden in the protocol while proper statistical tools should be adopted to process the data provided by the N participants in different cases. Intercomparisons are here subdivided into different classes according to the probability model type that represents the stochastic variability of the involved data. This paper also introduces the use of a mixture probability model to characterize the temperature data supplied in temperature intercomparison as a single population. In this approach, the reference value of the intercomparison becomes the natural definition of the expected value of this mixture probability function.

关键词： probability functions EXPECTATION VALUE reference value interlaboratory comparison Exercise Process comparisons Temperature data

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Sidelobe blanking with integration and target fluctuation

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 2002年第3期38卷 1023-1037页

作者： Shnidman, DA Toumodge, SS RADET Consulting Lexington MA 02420 USA Raytheon Elect Syst El Segundo CA 90245 USA

In radar systems, sidelobe blanking (SLB) is used to mitigate impulsive interference that enters the radar through sidelobes of the main antenna. SLB employs an auxiliary antenna channel with the output being compared with that of the main antenna channel and a decision is then made as to whether or not to blank the main channel output. SLB performance determination involves the evaluation of several probability functions. Based on the classical Maisel SLB architecture, this work extends previous performance results, in which detection was limited to the case of a single radar pulse with either Marcum or Swerling I target fluctuation. probability expressions have been generalized to include both an arbitrary number of integrated pulses and target fluctuation models based on the gamma distribution. The Swerling fluctuation models are all special cases of the gamma distribution. Results are derived in terms of two generalized probability functions, one for detection and the other for blanking. With these generalized probability functions, the SLB design and performance results can be determined. Examples are presented and discussed. Performance results of typical SLB systems are obtained and graphically illustrated.

关键词： radar antennas antenna radiation patterns radar interference gamma distribution sidelobe blanking impulsive interference auxiliary antenna channel probability functions single radar pulse Marcum target fluctuation Swerli Gamma Distribution antenna radiation patterns probability functions Radar antennas impulsive interference Radar pulses SHALLOW LAND BURIAL

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Scalability problems of RED

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ELECTRONICS LETTERS 2002年第21期38卷 1297-1298页

作者： Joo, C Bahk, S Seoul Natl Univ Sch Elect Engn Seoul South Korea

Random early detection (RED) can be helpful for Transport Control Protocol to control congestion by dropping packets before its queue becomes full. However, falsely configured RED causes network oscillation and simply works as a tail drop under the heavy load. To overcome the scalability problems of RED, an algorithm is proposed that adjusts the steepness of the drop probability function properly under various network conditions.

关键词： Scalability drop-in probability Transmission control protocol probability functions Gradient Heavy loads Network Queue

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Absolute probability functions for intuitionistic propositional logic

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JOURNAL OF PHILOSOPHICAL LOGIC 1999年第3期28卷 223-234页

作者： Roeper, P Leblanc, H Australian Natl Univ Dept Philosophy Canberra ACT 0200 Australia

Provides a characterization of absolute probability functions for intuitionistic (propositional) logic. Set of constraints on the unary functions P from the statements of L to the reals; probability semantics.

关键词： intuitionistic logic probability functions probability semantics

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The influence of turbulence on plankton predation strategies

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JOURNAL OF THEORETICAL BIOLOGY 2001年第3期210卷 347-365页

作者： Lewis, DM Pedley, TJ Univ Cambridge Dept Appl Math & Theoret Phys Cambridge CB3 9EW England

The importance of predation in regulating the size of competing plankton and larval fish populations has long been appreciated. However, it has only recently been recognized that turbulence must have a significant influence on predator-prey interactions because most rival species of microorganisms co-exist in oceanic or fast moving fresh water Rows. Turbulence is likely to influence predation strategies in two ways. The extra energy imparted to a microorganism from the flow field will enhance the number of encounters or "contacts" between predators and prey. At the same time, because the velocity of a predator relative to its potential prey will be increased, the time-scale over which a capture must be completed is reduced. Balancing the benefits of extra encounters: with the drawbacks of more difficult captures, will dictate an optimal predation strategy, either foraging behaviour or ambush feeding, on the predator. This will depend on its own and the prey's swimming capabilities, as well as the characteristics of the turbulent environment. In this paper some previous work, examining the increased encounter rate in turbulence, will be extended to look at the capture problem. The main proposal is that the capture event should be encapsulated in a capture probability function, from which the optimal predation strategy can be derived. As an illustration, plausible capture probability functions will be postulated and the resulting predictions tested against numerical simulations carried out in a turbulent-like Row field. Good agreement between the predictions and the simulations is demonstrated. (C) 2001 Academic Press.

关键词： Animal Nutrition Computer Simulation Environment Plankton 动物营养计算机模拟环境浮游生物 Turbulent Flow probability functions Fish populations Environments animal nutrition Microbes Predators plankton ENCOUNTERS Predatory Behavior flow field

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Effect of metastable atom reactions on the electron energy probability functions in afterglows

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PLASMA SOURCES SCIENCE & TECHNOLOGY 1998年第4期7卷 512-523页

作者： Overzet, LJ Kleber, J Univ Texas Plasma Applicat Lab Richardson TX 75083 USA

Time resolved electron densities, temperatures and energy probability functions (EEPFs) of modulated-power glow discharges through argon and helium in the Gaseous Electronics Conference reference reactor have been measured using an RF compensated Langmuir probe and a microwave interferometer. RF power was capacitively coupled to the glow and square wave amplitude modulated with a 50% duty cycle and 100% modulation depth. We found that a metastable-metastable ionization reaction can produce energetic electrons during the afterglow. This reaction can also cause the electron density to increase during the afterglow despite the RF excitation being off. The electron density as a function of time can be modelled and the result is an estimated metastable atom density as a function of time. The hot electrons in the EEPF can also be modelled, but the modelling result does not fit the experimental EEPF until the smoothing of the EEPF caused by the experimental method is taken into account. This smoothing of the EEPF can be accounted for using the Druyvesteyn method formula and indicates that accurate measurements of the EEPF in very low electron temperature plasmas can become difficult. In effect, one should have some knowledge of the shape of the EEPF before the experiment in order to obtain an accurate measurement. The electron density and EEPF results become self-consistent once the smoothing is taken into account. By moving the Langmuir probe along the diameter of the chamber it was determined that the electron density decreases more quickly between the electrodes than outside the electrode edges. This causes the plasma density profile in argon to becomes doughnut shaped during the afterglow and causes the glow to re-ignite from the edges into the centre. The electron temperature at re-ignition in helium discharges can become larger than that at steady state in the active glow. It quickly relaxes to the steady state value. This last effect is not nearly as pronounced in a

关键词： luminescence radiofrequency TIME functions electron energy Electron density afterglows smoothing probability functions Argon DUTY CYCLE electron temperature

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Low-grazing-angle monostatic acoustic reverberation from rough and heterogeneous seafloors

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JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2000年第3期108卷 1013-1025页

作者： Greaves, RJ Stephen, RA MIT Woods Hole Oceanog Inst Joint Program Woods Hole MA 02543 USA

Numerical wavefield modeling, based on time domain finite difference solutions to the full elastic wave equation, is used to quantitatively predict the sensitivity of monostatic backscatter to variations in geological properties of the seabed. This article addresses the hypothesis that observed backscatter signals from the seafloor are produced by a combination of seafloor (interface) and subseafloor (volume) scattering from structures having variations at scale lengths comparable to the wavelength of the insonifying acoustic field. Wavelength-scale seafloor roughness and subseafloor volume heterogeneity parameters are defined using stochastic spatial probability functions having Gaussian autocorrelations. The range of the variations in these parameters is constrained to realistic values based on estimates derived from seafloor bathymetry and other geologic data. Modeling results show that backscattering from rough, basaltic (hard) bottoms, in the absence of large-scale seafloor slope, is dominated by rough surface scattering with little contribution from volume scattering. Contrary to this, sediment (soft) bottoms with subseafloor volume heterogeneity, with or without seafloor roughness, produce significant backscattering signals compared to a homogeneous sediment bottom. (C) 2000 Acoustical Society of America. [S0001-4966(00)03309-9].

关键词： probability functions volume scattering ocean floors surface scattering TIME-DOMAIN scale length Gauss backscattering Reverberation

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Orientational disorder as a function of temperature in the clathrate structure of hydroquinone and C₆₀

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ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE 2000年第6期56卷 1003-1010页

作者： Blanc, E Restori, R Schwarzenbach, D Bürgi, HB Förtsch, M Venugopalan, P Ermer, O Univ Lausanne Inst Crystallog BSP CH-1015 Lausanne Switzerland Univ Bern Crystallog Lab CH-3012 Bern Switzerland Univ Cologne Inst Organ Chem D-50939 Cologne Germany

In the compound [C6H6O2](3)C-60, hydroquinone (C6H6O2) forms a three-dimensional hydrogen-bonded network enclosing roughly spherical cages with point symmetry (3) over barm and a diameter of 13.2 Angstrom at 100 K. Although C-60 fits tightly into these cages, it shows threefold orientational disorder, the molecular site symmetry being 2/m. The disorder has been studied with single-crystal Mo K alpha X-ray data at four temperatures, 100, 200, 293 and 373 K. In the refinement, C-60 was restrained to the icosahedral molecular symmetry m(35) over bar and to rigid-body translational and librational displacements including third- and fourth-order cumulants to account for curvilinear atomic movements, R(|F|) = 3.2-4.7%. At 100 K, bond lengths in C-60 refine to the expected values 1.450 (1) and 1.388 (1) Angstrom. The ratio of these values increases with increasing temperature, but the radius of the molecule remains constant at 3.537 (2) Angstrom. The r.m.s. libration amplitudes of C-60 are relatively small (5.5 degrees at 373 K) and the probability function of orientations of C-60 inside the cage shows large values only at the refined positions, indicating that the energy barrier of reorientation is large. Refinement of an ordered twinned structure was unsuccessful;the orientations of neighboring C-60 appear to be uncorrelated.

关键词： Vocational Rehabilitation orientation disorder probability functions Angstrom Energy barrier function of temperature clathrate hydroquinone cages

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