Cognitive models in biomimetic pattern cognition

We describe a new model which is based on the concept of cognizing theory. The method identifies subsets of the data which are embedded in arbitrary oriented lower dimensional space. We definite k-mean covering, and study its property. Covering subsets of points are repeatedly sampled to construct trial geometry space of various dimensions. The sampling corresponding to the feature space having the best cognition ability between a mode near zero and the rest is selected and the data points are partitioned on the basis of the best cognition ability. The repeated sampling then continues recursively on each block of the data. We propose this algorithm based on cognition models. The experimental results for face recognition demonstrate that the correct rejection rate of the test samples excluded in the classes of training samples is very high and effective.

The new concepts and new developments in hte theory of polymer crystallization

Recently a debate about the initial crystallization process which has not been the hotspot for a long time since the theory proposed by Hoffman- Lauritzen (LH) dominated the field arose again. For a long time the Hoffman-Lauritzen model was always confronted by criticism,and some of the points were taken up and led to modifications, but the foundation remained unchanged which deemed that before the nucleation and crystallization the system was uniform. In this article the classical nucleation and growth theory of polymer crystallization was reviewed, and the confusion of the explanations to the polymer crystallization phenomenon was pointed out. LH theory assumes that the growth of lamellae is by the direct attachment of chain sequences from the melt onto smooth lateral sides.

A study of a molecular mechanics field used in simulating enantiorecognition

A molecular mechanics field, Alchemy II, was utilized to model the chiral recognition between S-N-acetyl-alpha-methyl-alpha-naphthylamine and (R, S)-N-(3, 5-dinitrophrnyl)-alpha-methyl-benzeneacetamide and between beta-cyclodextrin and (R, S)-fenoprofen. Some preliminary results have: been obtained to sustain the three-point action models and the induce-fit action in enantiorecognition.

Flood Routing Models in Confluent and Dividing Channels

By introducing a water depth connecting formula, the hydraulic equations in the dividing channel system were coupled and the relation of discharge distribution between the branches of the dividing channels can be yielded. In this manner, a numerical model for the confluent channels was established to study the variation of backwater effects with the parameters in the channel junction. The meeting of flood peaks in the mainstream and tributary can be analyzed with this model. The flood peak meeting is found to be a major factor for the extremely high water level in the mainstream during the 1998 Yangtze River flood. Subsequently the variations of discharge distribution and water level with channel parameters between each branch in this system were studied as well. As a result, flood evolution caused by Jingjiang River shortcut and sediment deposition in the entrance of dividing channels of the Yangtze River may be qualitatively elucidated. It is suggested to be an effective measure for flood mitigation to enhance regulation capability of reservoirs available upstream of the tributaries and harness branch entrance channels.

Electric field enhancement in guided-mode resonance filters

Electric fields inside guided-mode resonance filters (GMRFs) may be intensified by resonance effects. The electric field enhancement is investigated in two GMRFs: one is resonant at normal incidence, the other at oblique incidence. It is shown that the two GMRFs exhibit different behaviors in their electric enhancement. Differences between the electric field distributions of the two GMRFs arise because coupling between counter-propagating modes occurs in the first case. It is also shown that the order of the electric field of maximum amplitude can be controlled by modulation of the dielectric constant of the grating. (c) 2006 Optical Society of America.

Electric field distribution in resonant reflection filters under normal incidence

Electric field distributions inside resonant reflection filters constructed using planar periodic waveguides are investigated in this paper. The electric fields may be intensified by resonance effects. Although the resonant reflection peaks can be quite narrow using weakly modulated planar periodic waveguides, the strong electric field enhancement limits their use in high-power laser systems. Strongly modulated waveguides may be used to reduce the electric field enhancement and a cover layer may be used to narrow the bandwidth at the same time. Desired results (i.e. almost no electric field enhancement together with narrow bandwidth) can be realized using this simple structure.

Magnetic field switching in parallel quantum dots

We show that the Coulomb blockade in parallel dots pierced by magnetic flux Phi completely blocks the resonant current for any value of Phi except for integer multiples of the flux quantum Phi(0). This non-analytic (switching) dependence of the current on Phi arises only when the dot states that carry the current are of the same energy. The time needed to reach the steady state, however, diverges when Phi -> n Phi(0). Copyright (C) EPLA, 2009

Current oscillations and stable electric field domains in doped GaAs/AlAs superlattices

The crossover between two regimes has been observed in the vertical electric transport of weakly coupled GaAs/AlAs superlattices (SLs). At fixed d.c. bias, the SLs can be triggered by illumination to switch from a regime of temporal current oscillation to the formation of a stable electric field domain. The conversion can be reversed by raising the sample temperature to about 200 K. An effective carrier injection model is proposed to explain the conversion processes, taking into account the contact resistance originating from DX centres in the n(+)-Al0.5Ga0.5As contact layers which is sensitive to light illumination and temperature. In addition, quasiperiodic oscillations have been observed at a particular d.c. bias voltage.

An investigation of the formation mechanisms of electric field domains in GaAs/AlAs superlattices

We have studied the vertical transport and formation mechanisms of electric field domains in doped weakly-coupled GaAs/AlAs superlattices. Under hydrostatic pressure two kinds of sequential resonant tunneling are observed within the pressure range from 0 to 4.5 kbar. A transition from Gamma-Gamma to Gamma-X sequential resonant tunneling occurs at P-t approximate to 1.6 kbar. For P < P-t, the high electric field domain is formed by the Gamma-Gamma process, while for P > P-t it is preferentially formed by the Gamma-X process.

Estimating water quality pollution impacts based on economic loss models in urbanization process in Xi'an；China

IEECAS SKLLQG

Superfluid nuclear matter in BCS theory and beyond

Medium polarization effects are studied for S-1(0) pairing in nuclear matter within BHF approach. The screening potential is calculated in the RPA limit, suitably renormalized to cure the low density mechanical instability of nuclear matter. The self-energy corrections are consistently included resulting in a strong depletion of the Fermi surface. The self-energy effects always lead to a quenching of the gap, whereas it is almost completely compensated by the anti-screening effect in nuclear matter.