Frequency response of loudspeakers by measuring theinduced e.m.f

1IntroductionTheperformanceofadirectradiatorloudspeakerisdirectIyrelatedtothediaphragmdis-placement.AccuratemeasurementoftIlefreqllenc,responseoftheloudspeakerbydifferentmethodsreqlliresananechoicchamberandacalibratednlicrophone.AI1echoicchambersoper-atingdowntorequiredlowfrequenciesareveryexpensive,a11dopenspacesareinconvenient.ThemethodsuggestedbyK.ele[l]isbasedonthefactthat,withsomerestrictions,thefarfieldfrequencyresponseofthespeakerissimilartothatofitsnearfieldresponse.Sincethereflected…     

Conformational Studies of α-Substituted Carbonyl Compounds by I. R. Spectroscopy. II. α-Heterosubstituted N,N-Diethylacetamides

Abstract

The α-heterosubstituted N, N?diethylacetamides(1–8) cis/gauche conformations population ratio have been estimated through the analysis of the carbonyl group stretching vibration in the carbon tetrachloride and in chloroform. The substituent steric properties determine the cis/gauche ratio which decreases as the substituent size increases. For most of the studied amides, the gauche rotamer carbonyl band exhibits larger shifts to lower frequencies than in the corresponding α-heterosubstituted propanones¹, but for the α-chloro-(4) and for the α-bromo-N,N?diethylacetamide(5) a reverse trend is observed. This behavior can be related to changes in the πC=O C—X Dihedral angle, an hyperconjugative effect being sugges ted to explain the frequency shifts of the gauche rotamers.     

Basics of Statistical Physics,by Harald J.W. Müller-Kirsten

Reactor Physics. By R. Schulten and W. Güth. Translated by W. K. Mansfield. In two volumes. (Harrap, 1967.) [Vol. I: pp. viii + 144; Vol. II: pp. vi+ 154.] 22s. 6d. each volume.

Principles of Atomic Spectra. By B. W. Shore and D. H. Menzel. (John Wiley, 1968.) [Pp. xiv + 538.] £8. 18s. 0d.

Les Transitions Electroniques dans les Solides Non Conducteurs. (Colloque de la Société Français de Physique.) (Presses Universitaires de la France, 1967.) [Pp. 177.] 35 F.

Mechanics. Point Objects and Particles. By Terry Triffet. (John Wiley, 1968.) [Pp. ix + 546.] 32s.

Traité ?Électricité Théorique, Vol. IV: Electromagnetism, etc. By Marc Jouguet. (Paris: Gauthier-Villars, 1968.) [Pp. 350.] 94 F.

Modern Physics: An Introductory Survey. By Arthur Beiser. (Addison-Wesley, 1968.) [Pp. ix + 221.] 26s.

Perpetual Motion: Electrons and Atoms in Crystals. By Alec T. Stewart. (Heinemann Educational Books, 1968.) [Pp. x + 146.] 25s.

An Introduction to the Theory of Superconductivity. By C. G. Kuper. (Clarendon Press: Oxford University Press, 1968.) [Pp. vii + 301.] 60s. Scope: Textbook. Level: Postgraduate; Undergraduate.

Progress in High Temperature Physics and Chemistry. Edited by C. A. Rouse. (Pergamon Press, 1968.) [Pp. 176.] 75s.

Ondes dans las Plasmas. By Daniel Quémada. (Paris: Hermann, 1968.) [Pp. 384.] 48 Fr.

Plasmas et Milieux Ionisés. By Evry Schatzman.(Presses Universitaires de la France, 1968.) [Pp. 134.] 16 Fr.

Mechanics. By R. C. Smith and P. Smith. (John Wiley &; Sons, 1968.) [Pp. xviii + 263.] 80s. Scope: Textbook. Level: Undergraduate.

Materials of High Vacuum Technology. Vol. 2: Silicates. By Werner Espe. (Pergamon Press, 1968.) [Pp xxiii + 660.] £16.

Glassblowing for Laboratory Technicians. By R. Barbour. (Pergamon Press, 1968.) [Pp XV + 245.] 40s.

Equilibrium Thermodynamics. By J. C. Adkins. (McGraw-Hill, 1968.) [Pp. xii + 283.] 48s. Scope: Textbook. Level: Undergraduate.

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Solid State Physics. An Introduction to its Theory. By H. Clark. (Macmillan, 1968.) [Pp. vii + 239.] 40s. Scope: Textbook. Level: Specialist/postgraduate.

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Introduction to Special Relativity. By Robert Resnick. (John Wiley, 1968.) [Pp. x + 226.] 70s.     

Comment on ‘Lifetime broadening in angle-resolved photoemission’ by A.B. McLean,C.E.J. Mitchell and I.G. Hill

In a recent letter [A.B. McLean, C.E.J. Mitchell and I.G. Hill, Surf. Sci. 314 (1994) L925] it was suggested that life-time broadening alone could explain why surface state photoemission line-widths have been observed to increase as the initial states approach the Fermi level. I wish to point out that the used model is unphysical, that the agreement with experimental data is quite fortuitous, and that the experimental observations are satisfactorily understood in terms of established models.     

Reply to a comment by S.N. Semenov and M.E. Schimpf on ‘Role of the velocity frame of reference in thermodiffusion in liquid mixtures’, Philosophical Magazine vol. 92, 705 (2012), by M. Eslamian,C.G. Jian and M.Z. Saghir.

A small angle X-ray scattering (SAXS) study of nanovoids in 99.988 and 99.995?at.% aluminium is presented. Absolute intensity calibration using a glassy carbon standard is used to extract the weak SAXS signature from nanovoids introduced by thermal quenching. SAXS analysis methods, including Guinier, Porod and Indirect Transform, are used to obtain values for the void–size, number distribution and volume fraction, as well as measures of the void-metal matrix interface structure in quenched aluminium samples. The SAXS analysis has identified a residual impurity effect on void formation and has been used to characterize trends in nanovoid size, number distribution and interface structure as a function of ageing time at elevated temperatures (artificial ageing). The work presented here, including identification of experimental tools that can be readily improved, demonstrates that SAXS studies are capable of providing precise characterization of nanovoid structure in aluminium. This level of information will be useful in developing phenomenological models of void nucleation and growth capable of linking atomic scale phenomena to macroscopic material properties.     

Citations for the Articles Published by CHINESE J.LUMINESCENCE in the Journals Covered by SCI

、。lllU七且，ou LUI，，，) 1980 1980，LUMD任洛CENCE DISPLAY，Vl(4)，玛1 WU GZ(吴光照)“Judd-of’ItI.叼d a.di妞apPlica如璐”[l〕印“如‘c.助“饥A抽吐，2(X)3，23(4):637七涛0 OPtieal pa幻到meters Of Er:YCa40(BO，)3e叮stal 1981 1981，LUM刃呵ESCENCE DISPLAY，V2(l)，巧2 XUY(徐燕)“Syll肠心山，c恤口州比冲川。朋d .pPlicado.orraree.“自加，咤目“pbo印ho“，’[l]日恤用.J.〔汤如.以成p.〔为加.，1995，1‘(6):844名46 Synth~of YZO3一Eu ph.phors with the meth记Of ntierowave一heating…