Correlation and letter recognition.

Used correlation functions obtained in 2 experiments with undergraduate Os (N = 10) as a basis for describing human visual letter recognition. Visual images were filtered by means of autocorrelation for pattern information. This operation gave the relative visibilities or legibilities of the characters. The visual impressions were then cross-correlated with a set of memory records whose outputs described the relative probabilities that the stimulus was a given character. This operation described confusion errors. Finally "response bias" was described in terms of the reliability with which a memory record provides identification of a given stimulus. In these terms response bias represented an attempt by the recognition system to minimize errors in high-information responses, at the expense of producing more low-information responses as errors. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

智能体在自然界建模中的应用研究

给出了动物模型的智能体设计和解决方案,扩展了智能体系统的概念。应用Swarm智能体系统和Kohonen网络,给出了一个将许多地貌、植物和动物结合起来Swarm解决方案。     

Indium tin oxide nanopillar electrodes in polymer/fullerene solar cells

Using high surface area nanostructured electrodes in organic photovoltaic (OPV) devices is a route to enhanced power conversion efficiency. In this paper, indium tin oxide (ITO) and hybrid ITO/SiO(2) nanopillars are employed as three-dimensional high surface area transparent electrodes in OPVs. The nanopillar arrays are fabricated via glancing angle deposition (GLAD) and electrochemically modified with nanofibrous PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate)). The structures are found to have increased surface area as characterized by porosimetry. When applied as anodes in polymer/fullerene OPVs (architecture: commercial ITO/GLAD ITO/PEDOT:PSS/P3HT:PCBM/Al, where P3HT is 2,5-diyl-poly(3-hexylthiophene) and PCBM is [6,6]-phenyl-C(61)-butyric acid methyl ester), the air-processed solar cells incorporating high surface area, PEDOT:PSS-modified ITO nanoelectrode arrays operate with improved performance relative to devices processed identically on unstructured, commercial ITO substrates. The resulting power conversion efficiency is 2.2% which is a third greater than for devices prepared on commercial ITO. To further refine the structure, insulating SiO(2) caps are added above the GLAD ITO nanopillars to produce a hybrid ITO/SiO(2) nanoelectrode. OPV devices based on this system show reduced electrical shorting and series resistance, and as a consequence, a further improved power conversion efficiency of 2.5% is recorded.     

Quantitative one-dimensional imaging using picosecond dual-broadband pure-rotational coherent anti-Stokes Raman spectroscopy

We employ picosecond dual-broadband pure-rotational coherent anti-Stokes Raman spectroscopy (CARS) in a one-dimensional (1D) imaging configuration. Temperature and O(2):N(2) concentration ratios are measured along a 1D line of up to 12 mm in length. The images consist of up to 330 individual rotational CARS (RCARS) spectra, corresponding to 330 spatially resolved volume elements in the probe volume. Signal levels are sufficient for the collection of single-laser-pulse images at temperatures of up to approximately 1200 K and shot-averaged images at flame temperatures, demonstrated at 2100 K. The precision of picosecond pure-rotational 1D imaging CARS is assessed by acquiring a series of 100 single-laser-pulse images in a heated flow of N(2) from 410 K-1200 K and evaluating a single volume element for temperature in each image. Accuracy is demonstrated by comparing temperatures from the evaluated averaged spectra to thermocouple readings in the heated flow. Deviations from the thermocouple of <30 K in the evaluated temperature were found at up to 1205 K. Accuracy and single-shot precision are compared to those reported for single-point nanosecond dual-broadband pure-RCARS and nanosecond 1D vibrational CARS.     

Internal reflection ellipsometry for real-time monitoring of polyelectrolyte multilayer growth onto tantalum pentoxide

Internal reflection ellipsometry was used for detection of the consecutive coating of two polyelectrolytes, poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA), onto a tantalum pentoxide (Ta₂O₅) substrate until the 10th bilayer. The UV patterned PAH-PAA-multilayer was characterized in air via ellipsometry and atomic force microscopy. Suited optical models enabled the determination of the layer thicknesses in wet and dry states. Linear multilayer formation could be proved by Attenuated Total Reflection — Fourier Transformed Infrared Spectroscopy measurements following the increase of the ν(C=O) band depending on the adsorption of the PAA. Streaming potential measurements after each layer deposition step indicated a change in surface charge after each layer deposition due to the consecutive coating of PAH and PAA. In this article the internal reflection ellipsometry is shown to be a convenient possibility to analyze the modification of a thin transparent Ta₂O₅ substrate.     

Modeling of surface acoustic wave strain sensors using coupling-of-modes analysis

SAW devices may be configured as strain sensors, providing passive, wireless strain measurement in demanding conditions. A key consideration is the modeling of the sensors, enabling different device designs to be considered. This paper presents a simulation scheme using coupling-of-modes (COM) analysis which allows both the frequency response of a SAW strain sensor and its bias sensitivity to be evaluated. Example applications are presented to demonstrate the use of the model.     

Permeation and diffusion of environmental pollutants through flexible polymers

Permeation and diffusion characteristics of high density polyethylene (HDPE), elasticized polyolefin, and polychloroprene membranes have been determined for various organic pollutants at 22 and 50°C. A standard ASTM permeation cell method was used to measure the permeation rate while an immersion/weight gain method was used to obtain the diffusion coefficient. Thickness-dependent permeation rates were determined for HDPE membranes. An equimolar mixture of various permeants was also used to see the possibility of synergistic effects by combination of permeants. The experimental results are discussed in relation to the suitability of HDPE membranes in severe environments.     

Molecular dynamics simulations of dislocation interaction with voids in nickel

A high density of voids is expected to form in irradiated face centered cubic metals, which can have a negative impact on the ductility and cause an increasing strength. Molecular dynamics simulations of the interaction between gliding dissociated edge dislocations and voids in nickel have been performed to investigate the effect of the void size, the corresponding detachment mechanism, and dynamic effects of the dislocation on the obstacle strength. As expected, the void strength is observed to increase with increasing void size. The dislocation interaction and detachment process are determined by the applied shear stress, the repulsive interaction between partial dislocations and the image interaction between the partial dislocations and the void surface. For voids with a diameter smaller than 2 nm, the repulsive stress between the partials dominates, resulting in the detachment of the leading partial from the void while the trailing partial remains pinned. Consequently, the detachment process and obstacle strength are controlled by the trailing partial. For voids with a diameter larger than 2 nm, the attraction between the dissociated dislocations and the void dominates causing the detachment process and void strength to be influenced by both partials individually. This transition in detachment process at a void diameter of 2 nm is consistent with other research, and this transition is shown to be dependent on the void separation distance along the dislocation line and the dissociation distance between the partials, thus the stacking fault energy. Finally, by comparing the quasi-static and dynamic simulation results, an estimate for the static detachment stress is proposed in terms of the dynamic detachment stress and the dislocation velocity after detachment.