歧义容忍度在二语习得中的研究

英语学习者在学习过程中经常不可避免的接触到各种语言层面的歧义现象,比如:语法层面、词汇层面、句法层面等。本文从心理和语言的角度介绍了歧义容忍度的概念。接着分析了歧义容忍度和二语学习的关系。在此基础上,介绍了歧义容忍度的测量方法。最后,文章概括性的讨论了歧义容忍度对二语习得的启示。     

Atomistic phenomena in dense fluid shock waves

The shock structure problem is one of the classical problems of fluid mechanics and at least for non-reacting dilute gases it has been considered essentially solved. Here we present a few recent findings, to show that this is not the case. There are still new physical effects to be discovered provided that the numerical technique is general enough to not rule them out a priori. While the results have been obtained for dense fluids, some of the effects might also be observable for shocks in dilute gases.     

Approximation of transient temperatures in complex geometries using fractional derivatives

It is shown that time-dependent temperatures in a transient, conductive system can be approximately modeled by a fractional-order differential equation, the order of which depends on the Biot number. This approximation is particularly suitable for complex shapes for which a first-principles approach is too difficult or computationally time-consuming. Analytical solutions of these equations can be written in terms of the Mittag-Leffler function. The approximation is especially useful if a suitable fractional-order controller is to be designed for the system.     

Discrete semi-stable distributions

The purpose of this paper is to introduce and study the concepts of discrete semi-stability and geometric semi-stability for distributions with support inZ ₊. We offer several properties, including characterizations, of discrete semi-stable distributions. We establish that these distributions posses the property of infinite divisibility and that their probability generating functions admit canonical representations that are analogous to those of their continuous counterparts. Properties of discrete geometric semi-stable distributions are deduced from the results obtained for discrete semi-stability. Several limit theorems are established and some examples are constructed.     

Damage and fracture evaluation of granular composite materials by digital image correlation method

This paper presents the applications of digital image correlation technique to the mesoscopic damage and fracture study of some granular based composite materials including steelfiber reinforced concrete, sandstone and crystal-polymer composite. The deformation fields of the composite materials resulted from stress localization were obtained by the correlation computation of the surface images with loading steps and thus the related damage prediction and fracture parameters were evaluated. The correlation searching could be performed either directly based on the gray levels of the digital images or from the wavelet transform (WT) coefficients of the transform spectrum. The latter was developed by the authors and showed higher resolution and sensitivity to the singularity detection. Because the displacement components came from the rough surfaces of the composite materials without any coats of gratings or fringes of optical interferometry, both surface profiles and the deformation fields of the composites were visualized which was helpful to compare each other to analyze the damage of those heterogeneous materials. The project supported by the National Natural Science Foundation of China (10125211 and 10072002), the Scientific Committee of Yunnan Province for the Program of Steel Fiber Reinforced Concrete, and the Institute of Chemical Materials, CAEP at Mianyang     

Investigation on chaotic motion in hysteretic non-linear suspension system with multi-frequency excitations

This paper presents the investigation on possible chaotic motion in a vehicle suspension system with hysteretic non-linearity, which is subjected to the multi-frequency excitation from road surface. The Melnikov’s function is used to derive the critical condition for the chaotic motion, and then it is investigated that the effects of parameters in non-linear damping on the chaotic field. The path from quasi-periodic to chaotic motion is found via Poincaré map and Lyapunov exponents.     

Phase Measurement Algorithm in Wavelength Scanned Fizeau Interferometer

Wavelength scanned interferometry allows the simultaneous measurement of top surface shape and optical thickness variation of a transparent object consisting of several parallel surfaces. Interference signals from these surfaces can be separated in frequency space, and their phases are detected by discrete Fourier analysis. However, these signal frequencies are shifted from the detection frequency by the refractive index dispersion of the object and a nonlinearity of the wavelength scanning. The Fourier analysis is sensitive to the detuning of the signal frequency and suffers from the multiple-beam interference noise. Conventional error-compensating algorithms cannot be applied to an object consisting of more than three reflecting surfaces. We derive a new 2N-1 sample error-compensating algorithm, which allows the phase detection of any order of harmonic frequency among the interference signals. The new algorithm suppresses the effect of signal frequency detuning as well as the multiple-beam interference noise and can be applied to the measurement of complex objects consisting of more than three reflecting surfaces.     

Interaction of two parallel plane jets of different velocities

The interaction of two parallel plane jets of different velocities is studied by flow visualization and PIV measurement to examine the influence of velocity ratio on the development ofjets in the initial region. It is found that the parallel plane jets develop toward the high velocity side and the jet width is reduced with a decrease in the jet velocity ratio. Corresponding to the variation of mean velocity field to the velocity ratio, the magnitudes of turbulence intensities, Reynolds stress and static pressure are weakened in the merging region of the jets and their peak locations of the properties are shifted to the high velocity side. These results indicate that the interaction of two parallel jets is weakened with a decrease in the velocity ratio of the jets.     

The 7th Asian Symposium on Visualization

The 7th Asian Symposium on Visualization (7ASV) was successfully held in Singapore from 3^rd to 7^th November 2003. This event was originally scheduled from 26^th to 30^th May 2003, but had to be postponed because of the outbreak of SARS (Severe Acute Respiratory Syndrome) in some parts of the world. A total number of 122 participants attended the Symposium of which, 107 were foreign participants from 16 countries (excluding Singapore) worldwide. There were 104 papers covering broad range of topics presented at the Symposium which were delivered in 2×7 long sessions, and 9 keynote papers.     

Modification of Spatial Coherence by Means of Low-Order Zernike-Mode Adaptive Optics

Spatial coherence of the field modified by low-order adaptive optics is analyzed to establish a theoretical basis for the recent idea of using adaptive optics as a spatial coherence modifier. In this context low-order adaptive optics has the ability to correct some of the low-order aberrations specified by Zernike polynomials. The initial field to be modified is assumed to be a spatially partially coherent one resulting from phase disturbance. It is demonstrated, as in the previous study, that low-order adaptive optics serves to enhance the spatial coherence of the resultant field and that the effect of the enhancement becomes stronger as the spatial coherence of the initially partially coherent field increases. Potential applications of low-order adaptive optics as a spatial coherence modifier are briefly discussed.