FOUNDATIONS OF PHYSICS LETTERS—List of Contents: Volume 11, Number 6, December 1998

Volume Contents

FOUNDATIONS OF PHYSICS LETTERS—List of Contents: Volume 11, Number 6, December 1998     

FOUNDATIONS OF PHYSICS LETTERS—List of Contents: Volume 11, Number 6, December 1998

Volume Contents

FOUNDATIONS OF PHYSICS LETTERS—List of Contents: Volume 11, Number 6, December 1998     

AIP HANDBOOK OF CONDENSER MICROPHONES Theory, calibration, and measurements

TheAIPHANDBOOKOFCONDENSERMICROPHONESeditedbyCanadianscientistsGeorgeS.K.WONGandF.W.EMBLETON,isoneinAIPseriesinModernAcousticsandSignalProcessing,RobertT.Beyer,seriesEditor-in-ChiefWONGisthedirectoroftheInstituteofNationa1MeasurementStandards,NationalRcsearchCouncil,Canada,andEMBLETONhispredecessorandnotedacousticianinnorthAmerica.Abookundereditorshipofsuchknowledgeab1escientistsisboundtobeexcellentinitscontentandpresentation.Thebookisagoodreferenceinstudying,te…     

β-MODIFICATION OF ISOTACTIC POLYPROPYLENE: PREPARATION,STRUCTURE, PROCESSING,PROPERTIES, AND APPLICATION

The methods of preparation and formation of supermolecular structures in quiescent and sheared melts and the properties of the β-modification of isotactic polypropylene (β-iPP) are reviewed. The introduction of selective β-nucleants is the most reliable method for preparation of samples rich in β-modification or of pure β-iPP. The advantages and drawbacks of the known β-nucleating agents are summarized. It is emphasized that pure β-iPP can be prepared under laboratory and processing conditions in the presence of highly active and selective β-nucleants. Nevertheless, there are no literature data—apart from that of the author's groups—which evidenced unambiguously the formation of pure β-iPP. It hints at the insufficient selectivity of β-nucleants used or at the inappropriate crystallization or melting conditions applied by other scientists. The structure formation during the high-temperature hedritic crystallization is discussed comprehensively and illustrated by polarized light microscopy and scanning electron microscopy micrographs. Some specific features of β-iPP, namely the high- and low-temperature growth transition, the restricted temperature range of the formation of pure β-iPP, and the unique melting and recrystallization characteristics (melting and annealing memory effect) are summarized. It was emphasized that impact strength and toughness of β-iPP markedly exceed those of α-iPP. Processing of β-nucleated iPP and application of β-nucleated iPP is described briefly.     

IDENTIFICATION AND SEPARATION OF THE TWO OVERLAPPING SINGLET 1(π, π*) ABSORPTION BANDS OF 1, 4-TETRACENEQUINONE

Absorption and fluorescence spectra of 1, 4-tetracenequinone (1, 4-TQ) have been measured in solution and the two overlapping 1(π, π^*) absorption bands with comparable intensities were separated. Based on the spectroscopic data, the energy levels of the low-lying 1(π, π^*) excited states of 6, 15-hexacenequinone were discussed in relation to those of 1, 4-TQ.     

DESCRIPTION OF A CALCULATION METHOD OF ELASTIC CONSTANTS OF CRYSTALS

With the help of the decline method,a computer-aided analysis program of Christoffel equation is des-cribed which makes it possible to calculate elastic and viscous constants of crystals precisely and easily.Theelastic constants of LiNbO_3 and Bi_(12)GeO_(20)crystals are calculated with an Apple-Ⅱcomputer and theFortran program suggested,and the calculated data are compared with the values achieved by others.     

STUDY OF ULTRASONIC PROPERTIES OF THE AQUEOUS SOLUTION OF GELATIN

The experimental investigation of aqueous solution of the gelatin has been made by usingultrasound at frequency 11.4 MHz.The relation between concentration and ultrasound absorptiondoes not reach its saturated value even at the weight concentration of the solution c=8.5%. When the concentration is more than l.5%,the solution transforms into jelly under room tem-porature,but the ultrasonic absorption does not change in the whole transformation proces.Whenthe temperature of the solution is decreased to the vicinity of gelling point,the viscosity η of the solutionincreases gradually with time,making the value of sound absorption calculated from η largerthan the experimental one by several orders.But when the temperature of the solution is appropriatelyhigher than the gelling point,the calculated value of sound absorption is smaller than the experimentalone but with the same order. The temperature at which the maximum sound velocity occurs in the concentrated(c=6.4%)solution is not much different from that     

RECENT PROGRESS OF(e,2e) SPECTROSCOPY

Recent progress of(e,2e)spectroscopy,or Electron Momentum Spectros-copy(EMS),on laser excited oriented atoms,large bio-organic moleculesand thin films is reviewed.     

GROWTH TECHNIQUE OF MOLECULAR CRYSTAL OF NAPHTHALENE

A furnace for growing single crystal naphthalene of diameter 1-1.3cm and length up to15cm has been constructed by the Bridgman method in combination with zone-melting technique.The furnace is simple in its construction,convenient in its operation and convenient for the observa-tion of the crystal growth process.The effect of the shape of crystal growth container on crystalgrowth is discussed and the experiment in vapor growth of small naphthalene flakes is described.The preparation procedure of naphthalene samples for ultrasonic measurement,which may be alsouseful for preparation of other soft crystals,is given.     

A METHOD OF DISPLAYING COLOR SPECTROGRAM OF SPEECH BY USE OF MICROCOMPUTER

A method of drawing color spectrogram of speech by using microcomputer is described in this paper,and referred to the metod of drawing spectrogram by computer.With the software and no addition anyother aqripment.,we can draw color three-dimension spectrogram(or black-white spectrogram with-out color monitor),and it is similar to spectrogram of sonagrapher.     

SCATTERING OF PLANE WAVE BY PIEZOELECTRIC CYLINDER——TRANSFER FUNCTION,TRANSIENT RESPONSES AND PHASE RECONSTRUCTION OF TRANSDUCER

In this paper,under Kirchhoff's assumptions,a theory of the thin shell of radially-Polarizedpiezoelectric ceramic cylinder has been developed.Using the methods of Green's function and separa-tion of variables the scattering of a plane wave by the cylinder has been solved.The normal modeseries expressions of the velocity distribution of the surface of the cylinder and of the total soundfield have been obtained and from those an exact analytic expression of the transfer function of thecylinder as a sound receiver has been give.Arbitrary transient response of the cylinder can be cal-culated from the transfer function by using FFT. For PZT-5 piezoelectric ceramic cylinder,the transfer function,impulse response and step responsehave been calculated.The results show that the impulse response displays a typical minmum phasebehaviour and the cylindrical piezoelectric receiver belongs to the minimum phase system.Therefore,the phase spectrum of transfer function of the receiver can be reconstructed from its amplit     

MULTIDIMENSIONAL ANALYSIS OF PERCEPTIONAL CONFUSION OF CHINESE CONSONANTS

The perceptional features of Chinese consonants has been analysed in multidimensional scalingby means of optimizing the fitting to the confusion probabilities of consonants as observed in articula-tion tests.The dependence of minimum Stress as criterion for fitting on dimensions has beenobtained. In this paper,a method of multidimensional scaling is described briefly.A program for perform-ing calculations on a programmable calculator and the questions of handling the blank data as wellas setting the starting configurations are discussed.Some typical results of calculation are given.     

Crystal field analysis of the magnetic properties of RFe11Ti and RFe11TiH （R=Sm, Tb, Ho）

The crystalline-electric-field parameters Anm for RFe11Ti and RFe11TiH （R=Sm, Tb, Ho） are evaluated by fitting calculations to the magnetization curves measured on the single crystals or on magnetically aligned powder samples at 4.2K and higher temperatures. Interstitial hydrogen atom in RFe11Ti has been found to have a significant effect on crystalline-electric-field parameters Anm. By using the parameters of exchange field 2μBHex estimated from inelastic neutron scattering experiments and the fitted Anm, the calculations can reproduce the experimental curves well.     

A METHOD OF PULSE-TO-PULSE CORRELATION FOR STUDY OF TIME-VARIANT CHARACTERISTICS OF UNDERWATER SOUND CHANNEL

A method of measuring correlation among signal pulses for investigation of random time-variantproperties of underwater sound channel is presented in this paper.The expression of correlationfunction between periodic pulses propagating in underwater sound channel is derived.The mea-sured results of the correlation coefficent of the received signal pulses in propagating channel andin fixed-target reflected channel are given.Primary analysis of measured results and a channel modelhave heen shown in this Paper.     

ANALYSIS OF SURFACE EXCITATION OF ELASTIC WAVE FIELD IN A HALF SPACE OF PIEZOELECTRIC CRYSTAL——GENERAL FORMULAE OF SURFACE EXCITATION OF ELASTIC WAVE FIELD

This paper developes the general theory of the surface excitation of elastic wave field in a halfspace of piezoelectric crystal for both free and metallized surfaces.It is shown that the general elas-tic wave field U is equal to the convolution of the generalized Green's functions G and the general-ized forces T, U = G Twhere symbol,expresses dot-product-convolution. The generalized Green's functions are independent of excitation conditions and only dependenton material parameters and orientation. For the piezoelectric crystal,not only a mechanical source distribution at the surface,but anelectrical source distribution can also excite the elastic wave fields.Complete expressions of thegeneralized forces representing mechanical and electrical source distribution respectively are given.Especially for the free surface,the surface electrical sources can be composed of the discontinuityof normal electric displacement at the surface,and of the discontinuity of the tangential electric fieldas well.     

NOVEL SYSTEMATICS OF AUTOIONIZATION AND RADIATIVE DECAY RATES OF DOUBLY EXCITED STATES OF ATOMS

We discuss the novel systematics and the calculation of autoionization and radiative decay rates of doubly excited states of atoms and ions where both electrons have high principal quantum numbers.     

DEVELOPMENT OF THE LAW OF TURBULENT JET NOISE

Lighthill's theory of aerodynamic noise is re-examined,and an equivalent of his U~8-law derived interms of pressures.The total acoustic power of jet noise is expressed as W=8KD~2(p_1-P_0)~4/(σ_0c_0P_1~2)K being the Lighthill's constant,D the diameter of the nozzle,P_1,the plenum pressure and P_0 theatmospheric pressure.This formula applies to cold-air jet at low pressures.Further development,theformula is generalized to high pressures,working material of molecular weight M at temperature T.Soundpressure level in the direction perpendicular to the jet is seen more exact to describe the field,and this at lmeter from the nozzle is found as L=80+10 log(R-1)~4/(R~2-R+0.5)+20 log(TM_0)/(T_0M)+20 log dwhere R=P_1/P_0 and d=diameter in mm.The general formula reduces to the empirical formulae uponneglecting some small terms.     

PRISE THE SECRET OF HETEROGENEITY OUT OF BIOPOLYMER SYSTEMS

High-resolution 13C spectra of solid polymers are often acquired with cross polarization with magic angle spinning (CP/MAS) to take advantage of the abunda ntly available protons in the polymer chains. The sequence for transferring mag netization from 1H to13C using Hartmann-Hahn spin locking in the rotating frame is now a standard in commercial solidstate NMR spectrometers.     

JOURNAL OF ENGINEERING THERMOPHYSICS VOl. 22, 2O01 CONTENTS

No.(pp.)Thermodynamic Analysis of Combined Cycle-Repowering of Traditional Steam-Turbine Plants…………………………………………………………………………………………………LIU Ze-Long JIN HongGuang CAI Rui-Xian JIANG Hong-De LIN Ru-Mou 1 (1 )Non-Equilibrium Thermodynamic Theory of External Heat and Mass Transfer During Convective Drying Process in PorousMedia……………………………………………………………………………………………………LI You-Rong ZENG Dan-Ling WU ShuangYing …