摘要:

Given an electric networkEvwhich hasMmeshes andPnode‐pairs, its electric dualEiwill havePmeshes andMnode‐pairs and its classical mechanical analogMfwill haveM+1 nodes,Mindependent node‐pairs, andPindependent node cycles. A second mechanical systemMv, the classical analog ofEi, will haveMcycles andPnode‐pairs. If, for example,M= 2,P= 3, the systemsEvandMv, analogs in the Firestone or “mobility” method, will be governed by two mesh equations, expressing that the algebraic sum of the voltages or velocities around any loop is zero; the systemsEiandMf, also Firestone analogs, will satisfy two node equations, expressing that the algebraic sum of the currents or forces leaving any node is zero. These four sets of equations are identical, interchanging symbols suitably. The consideration of the four systems,Ev,Ei,Mv,Mf, forming a complete set, shows the advantages of the Firestone over the classical system of analogies and suggests a systematic use of duality in mechanical as well as in electrical systems.

ISSN:0001-4966    

DOI:10.1121/1.1906947

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

A hydrodynamical test system for absolute measurement of analogous impedance of acoustic elements is described. The test system is designed for use from dc to 700 cps, and in this frequency range it accurately measures pressure and volume flow.

ISSN:0001-4966    

DOI:10.1121/1.1906948

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

Some aspects of the periodic flow of an incompressible fluid through a circular tube of large length to diameter ratio have been studied. Expressions for the analogous acoustic resistance and inductance of the tube are presented. An experimental investigation of the resistance and inductance is described in which the tube dimensions, the viscosity of the fluid, and the frequency of the periodic motion are varied over a wide range. The experimental results are found to be in good agreement with the predictions of the hydro‐dynamical theory.

ISSN:0001-4966    

DOI:10.1121/1.1906949

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

With the advent of barium titanate as a piezoelectric material, the construction of transducers whose active elements can be in a wide variety of shapes became possible. The theoretical sensitivity of an interesting structure consisting of a transversely loaded, centrally supported, circular, barium titanate bimorph is calculated using the results of elasticity theory. Some experimental verification is presented.

ISSN:0001-4966    

DOI:10.1121/1.1906950

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

The record‐playback method of making noise comparison tests provides realistic answers with a minimum of equipment and sophistication. Such a method is especially attractive in problems handled by making experimental changes which, taken individually, usually produce very small changes in level and quality of noise.In automotive work, playback of single‐channel recordings of interior car noise sensed by a single microphone sound unreal because of an emphasized bass, the cause of which is not known to the author. Directional effects also contribute to the lack of realism.The use of a binaural magnetic tape recorder improves realism, which in turn enhances the resolution of smaller differences.

ISSN:0001-4966    

DOI:10.1121/1.1906951

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

The calculations presented in PartIof this paper have been extended so as to include vibrations, which are antisymmetric with respect to the central plane of the disk. Curves showing the normal components of the displacements at the boundary surfaces are also drawn, to get the vibration patterns according to the theoretical assumptions made.

ISSN:0001-4966    

DOI:10.1121/1.1906952

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

The aerothermodynamic process inside a tube in which is placed heat source and through which air is flowing is investigated theoretically. The formulation is based partly on the assumption that the average state of the medium inside may be approximated by a step distribution in the gas variables, simplifying hypothesis suggested by experimental observations by Lehmann (see reference 4). The zeroth‐order (mean hydrodynamic flow) and first‐order (acoustic) solutions inside the tube are first obtained using a heat transfer law for the heater which depends on some arbitrary function of the local values of the gas variables, velocity‐gradient, and source temperature. Upon the basis of a few hypotheses regarding turbulent flow and turbulent heat transfer, the possible existence of heaters whose heat transfer rate depends essentially on the negative of the velocity gradient of the flow through them is demonstrated. The solution is then specialized to those types of heaters, and it is shown that, in agreement with the so‐called Rijke effect, growth of the fundamental tone may occur with the heater almost anywhere in the first half of the tube from the blower end to the node, with decay almost everywhere else. The exact positions of the regions of growth and decay of sound inside the tube are then investigated.

ISSN:0001-4966    

DOI:10.1121/1.1906954

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

Measured dependences of thePfeifentonfrequency on static flow pressure, orifice diameter, and pipe length are presented, based upon studies of air flowing through pipes terminated various orifices. Frequency measurements were made of the vibrations inside the pipe. ThePfeifentöneare not a series of discrete single valued harmonics. Each covers a range of frequencies, any specific value of which is determined by the discharge flow‐velocity or pressure. When the orifice diameter approaches zero the behavior of theprimary Pfeifentonfrequencies is as if they were produced by an open‐closed organ pipe; when the orifice diameter approaches that of the pipe, the behavior is as if they were produced by an open‐open organ pipe. A mechanism for the excitation of thePfeifentöneis proposed.

ISSN:0001-4966    

DOI:10.1121/1.1906955

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

An unusual type of vibration of flattened spheroidal liquid drops, occurring under certain conditions, is described and illustrated. Appropriate liquids placed on a sufficiently hot horizontal surface float on a film of their own vapor, which vapor insulates the drop so that it evaporates quite slowly, this phenomenon being known as the Leidenfrost effect. It is under these conditions that drops have been found capable of sustaining large amplitude regular radial vibrations whose driving force is probably related to the radial flow of vapor below the drops. The vibrating drops are approximately polygons which may have any of 2, 3, 4,…nsides, seen by the eye as drops with 4, 6, 8…(2n+2) regular lobes around the circumference. Methods of exciting and recording the effect are described.

ISSN:0001-4966    

DOI:10.1121/1.1906956

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP

摘要:

An analysis is made of certain methods of measuring the velocity of sound. Specifically, attention is centered on those methods based upon measurements of the electrical driving‐point impedance of the transducer and the observation of some phenomenon of that impedance which is recurrent as the position of the reflector in the acoustic chamber is changed. Consideration is given to the influences of small losses in the propagation of sound in the chamber and of the existence of nonplane wave fronts. It is shown that such measurements can be subject to significant systematic errors arising from the method itself. The nature and magnitude of such errors are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1906957

出版商:Acoustical Society of America    

年代:1952

数据来源: AIP