电荷密度波状态下的TaS_3的某些动态特性及其可能的电子学应用

本文对处在电荷密度波(CDW''S)状态下的TaS₃的直流及交流导电特性进行了仔细的观测,揭示出准一维导体TaS₃的交流响应中滞后现象及相移的存在,演示了准一维导体TaS₃在其转换温度以下所具有的强烈非线性导电特性的各种可能的电子学应用(包括频率转换、调制、外差等),展示了一类新的体效应CDW''S电子器件的可能性。文中还提出了一个电路模型,唯象地描述了所观察到的实验现现象。     

Fluorescence of fly ash samples: Implications for in situ and remote detection

A study of the fluorescence spectra of fly ash samples from different sources has shown that each samples has a characteristic fluorescence and excitation spectrum which could be used to identify and monitor its presence. Fluorescence lifetime studies of samples from different sources have demonstrated characteristic features which can be used for identification. The fluorescence method should be useful for in situ and remote monitoring applications.     

Coupled nuclear and electronic spin-wave modes

The dispersion relation for the coupled nuclear and electronic spin-wave modes that exist in magnetically ordered materials due to the hyperfine interaction is derived by means of a diagrammatic method employing the drone-fermion representation.     

Nuclear disintegration in relativistic heavy ion collisions

The breakdown of the participant spectator model for central relativistic nuclear collisions is discussed and a different picture of a hot spot followed by a target explosion is suggested to be more consistent with the data.     

Phonons from powder diffraction: a quantitative model-independent evaluation

We describe a model-independent approach for the extraction of detailed lattice dynamics information from neutron powder diffraction data, based on a statistical analysis of atomistic configurations generated using reverse Monte Carlo structural refinement. Phonon dispersion curves for MgO extracted in this way are shown to reproduce many of the important features found in those determined independently using neutron triple-axis spectroscopy. By means of molecular dynamics simulations, we quantify the extent to which the diffraction data are sensitive to lattice dynamics in this system.     

A multidimensional discrete variable representation basis obtained by simultaneous diagonalization

Direct product basis functions are frequently used in quantum dynamics calculations, but they are poor in the sense that many such functions are required to converge a spectrum, compute a rate constant, etc. Much better, contracted, basis functions, that account for coupling between coordinates, can be obtained by diagonalizing reduced dimension Hamiltonians. If a direct product basis is used, it is advantageous to use discrete variable representation (DVR) basis functions because matrix representations of functions of coordinates are diagonal in the DVR. By diagonalizing matrices representing coordinates it is straightforward to obtain the DVR that corresponds to any direct product basis. Because contracted basis functions are eigenfunctions of reduced dimension Hamiltonians that include coupling terms they are not direct product functions. The advantages of contracted basis functions and the advantages of the DVR therefore appear to be mutually exclusive. A DVR that corresponds to contracted functions is unknown. In this paper we propose such a DVR. It spans the same space as a contracted basis, but in it matrix representations of coordinates are diagonal. The DVR basis functions are chosen to achieve maximal diagonality of coordinate matrices. We assess the accuracy of this DVR by applying it to model four-dimensional problems.     

An approach to modelling industrial unit processes: application to a spiral concentrator for minerals

A suite of computer models which simulate process operations in common use in the minerals processing industry is being developed. Application of the models is described with reference to a particular process device, the spiral concentrator. The paper sets out to explain the basic strategy behind the unit process modelling approach and discusses in detail the overall model structure adopted. The model aims to provide a set of equations, with sufficient physical significance to give a reasonable fit to any specific data set, and which can be systematically adjusted (through auxiliary models, user judgement and experience) to provide meaningful performance predictions over a broad range of operating conditions. The approach is thought to be applicable to a wide variety of processes. The model has been tested using a variety of ores, separated on plant-scale equipment and practical examples are given. The scope and limitations of the method are reported, drawing on the results of parallel experimental work. The extent to which this kind of approach can be used as a predictive tool in process design applications and in the day-to-day running of mineral processing plant is discussed.