A short history of heavy ion beam probing

The author describes some aspects of research on controlled thermonuclear fusion as an energy source, starting in the late 1950s. There was a need for new diagnostic techniques for studying high temperature plasmas. The author proposed a diagnostic for measuring plasma density by probing a deuterium plasma with a deuterium beam and measuring the proton production from the D-D nuclear reaction. By the mid 1960s, it was possible to do so. After carrying out a D-D measurement, the author suggested switching over to an H₂⁺ beam and looking for an H⁺ signal. The H+ was loud and clear and that was the last of the nuclear measurements. One of the first things done using the molecular break-up of the H₂⁺ to measure the density of the hollow cathode arc plasma was a study of a coherent instability. The frequency response wasn't sufficient to measure the instability directly, so a Langmuir probe was used to detect the instability. The Langmuir probe gave a signal from a fixed spatial location but the beam probe signal was swept across the plasma giving 2D spatial resolution. This was the first detailed mapping of a plasma instability. Attempts to apply the ion beam probe to measuring the plasma current density in the ST Tokamak are described. Heavy ion beam probing measurements using hollow cathode arcs as target plasmas made it possible to measure T_e at low temperatures and to identify space potential fluctuations. Installation of a beam probe on the Laser Initiated Target Experiment are described, along with work on the ELMO Bumpy Torus, the VERSATOR Tokamak, TMX, TEXT, ISX-B, the Ergodic Magnetic Limiter and ATF     

A short history of nuclear magnetic moments and GT transitions

We summarize the history and our present understanding of nuclear magnetic moments and Gamow-Teller transitions.The roles of configuration mixing,meson exchange currents and relativistic effects are examined.Experimental evidence for the importance of tensor correlations is also discussed.     

A short history of measurement standards at the National Physical Laboratory

Measurement science has been one of the major interests of the NPL since the creation of the Laboratory in 1900. This article gives a historical review of NPL work on the establishment, maintenance and improvement of the basic standards of measurement for mechanics, electro-magnetics, thermometry, photometry and radiology. Many early NPL standards and essential components of classioal measuring equipment have now been assembled into a permanent collection for preservation at the Laboratory and illustrations of some items in this collection are reproduced in the article.     

A shadowgraph method for ocean acoustics

A knowledge of convection activity in the upper few hundred metres of the ocean is important in establishing ocean-atmosphere heat fluxes and in understanding large-scale water-circulation processes. The usual methods for investigating internal structures in the ocean have certain drawbacks. Lowering probes into the ocean can provide local information only, while towed arrays of sensors are cumbersome and expensive. An alternative acoustic method for revealing internal structures is proposed. It is based on the observed acoustic intensity only and does not rely on phase or travel times. For this reason it is really an acoustic shadowgraph. The method is explained and its successful use in a sea trial is reported.     

Contracting acoustics

This letter covers the subject of the evaluation of tenders for both noise control products, and items with acoustic features which are evaluated at the tender stage of a contract. Examples taken from different fields show that, at the present time, there is a need for manufacturers of noise control products, etc, to understand normal tendering procedure. Such procedures are reviewed in the first part of this note.     

Courtyard acoustics

The acoustic environment of courtyard housing has been studied and the ability of the courtyard to attenuate external noise examined. A scale-model was used to study the effect of the ground treatment, the source and the receiver locations, the depth of the courtyard and the position and arrangement of openings in the walls.Experimental results obtained from the model, together with a simple procedure for predicting the sound pressure levels inside the courtyard, are presented.     

A beam tracing method for interactive architectural acoustics

A difficult challenge in geometrical acoustic modeling is computing propagation paths from sound sources to receivers fast enough for interactive applications. This paper describes a beam tracing method that enables interactive updates of propagation paths from a stationary source to a moving receiver in large building interiors. During a precomputation phase, convex polyhedral beams traced from the location of each sound source are stored in a "beam tree" representing the regions of space reachable by potential sequences of transmissions, diffractions, and specular reflections at surfaces of a 3D polygonal model. Then, during an interactive phase, the precomputed beam tree(s) are used to generate propagation paths from the source(s) to any receiver location at interactive rates. The key features of this beam tracing method are (1) it scales to support large building environments, (2) it models propagation due to edge diffraction, (3) it finds all propagation paths up to a given termination criterion without exhaustive search or risk of under-sampling, and (4) it updates propagation paths at interactive rates. The method has been demonstrated to work effectively in interactive acoustic design and virtual walkthrough applications.     

Nonlinear acoustics in Nizhni Novgorod (A review)

This article reviews the development of nonlinear acoustics in Nizhni Novgorod from the days when the idea of parametric transmission and reception was conceived until the present time.     

A corona-type point source for model studies in acoustics

This paper describes a corona-type point source suitable for acoustic measurement purposes, especially model studies in acoustics. This source operates within a wide frequency range from 1 kHz to 100 kHz. The characteristics of this sound source were investigated and were found to be very close to those of a theoretical point source. It also gives a satisfactory sound power level.     

语言声学的进展

本文涉及语言声学的语音学研究、文语转换技术、语音识别技术及自然语言处理等方面，简要介绍了有关汉语在前三方面的进展和发展方向；重点介绍了面向整个自然语言理解处理的新理论一概念层次网络（HNC）理论的主要内容及其进展，试图在理论层面上给出HNC理论的基本概貌。     

语言声学进展及其应用

本文对语言声学研究的最新进展进行综述。首先介绍了人类的言语的产生和感知以及声学分析方面的近期发展,接着重点阐述了计算机处理人类语音(包括语音识别和合成,发音评估以及演唱评价)的最新研究、成果。同时提及了这些研究成果的相关应用。最后是总结与展望。