bluuebunny/crossref_metadata_2025_split huggingface dataset:
Message Repetition and Receiver Confirmation of Messages in Noise
Authors: Carterette Edward C. 
Published: September 2005

A receiver may be required to decide whether the message he has recorded is or is not the message actually received. The degree of certainty needed for confirmation (the criterion) may be controlled by instructions. A sequence of decisions is generated by repeatedly sending each of a set of messages until the set is confirmed. A simple stochastic model assumes that the probability of confirmation, py, is constant over such a sequence. If N messages are sent, the expected number confirmed after the first n presentations is E(n) = N[1 − (1 − py)n].
Two experimental tests were (1) of the constancy of py by noting whether the equation for E(n) holds, and (2) of the constancy of py's three component probabilities: the probabilities of correct reception, correct confirmation, and incorrect confirmation. Receivers listened under two noise conditions to sets of several hundred messages each. Each message was immediately repeated until confirmed. Estimates of py and of the component probabilities were made from proportions of correct and incorrect responses. The data show that the assumption of constant py yields a very accurate description of the process, and justify the more basic assumption that py's three components are constant over repeated trials. Further, the data are in excellent agreement with predictions from the theory of the total number of communication events required before the entire set of N messages is confirmed, and of the total numbers of correct and incorrect confirmations.
The Space-Time Patterns of the Cochlear Microphonic in Guinea Pig
Authors: Tasaki I. , Davis H. , Legouix J.-P. 
Published: September 2005

Two or three pairs of nichrome steel electrodes (20μ) are inserted into each of two or three turns of the cochlea of guinea pig. One electrode of each pair is in scala tympani, one is scala vestibuli. Such “differential” leads record nearly pure cochlear microphonics from segments of the cochlear partition only about 1 mm long. Low tones evoke microphonics from all four turns; but as the frequency is increased (holding the response from the basal turn constant by adjusting the intensity of sound), the microphonic ceases, first at the apical turn, then at the third turn, and finally at the second turn. The normal space pattern for each frequency as revealed by its cochlear microphonic is a long plateau rising slowly from the basal end but with a much more abrupt fall toward the apex. The locus of this abrupt fall is characteristic for each frequency. The space-time pattern of an acoustic signal is a decelerating traveling wave moving from base toward apex. The velocity of a 500-cycle wave falls from about 70 m/sec in the basal turn to about 2 m/sec near the helicotrema. These electrical patterns are in general agreement with the mechanical patterns described by Békésy.
The space and space-time patterns remain normal even when large sections have been removed from the bony shell of the second turn, over both scala vestibuli and scala tympani. The traveling wave still originates in the basal turn even when the cochlea is stimulated by sound transmitted through the fluid in a small pipette that enters scala vestibuli of the third turn through a hole in the bony shell.
Sources of Vorticity in Acoustic Fields
Authors: Medwin Herman , Rudnick Isadore 
Published: September 2005

When a sound beam passes through a viscous fluid, vorticity is generated as a second-order effect and streaming results. The work of Eckart, which considers the vorticity generated in the medium, is extended to consider “surface sources” of vorticity which appear when the sound beam makes contact with a solid, restraining surface. Further, the way in which the results depend on the following assumptions: (1) the viscosity coefficient μ or (2) the kinematic coefficient of viscosity ν = μ/ρ, being constant for changes in density, is shown for fluids. With these generalizations, previous work on streaming by other authors is discussed and reconciled.
The streaming in two particular boundary cases is considered: (1) a plane progressive wave which contacts an enclosing cylindrical tube, and (2) a small, rigid, fixed sphere in a standing wave in air. In both cases it is shown that the predominant sources are the “surface sources.” This work was supported in part by Contract N6onr-27507.
Temperature Variation of the Adiabatic Elastic Constants of Aluminum
Authors: Long T. R. , Smith Charles S. 
Published: September 2005

The elastic constants of a single crystal of aluminum have been measured by the pulsed ultrasonic technique in the temperature range from 80° to 300°K. It was found that all of the elastic constants decreased linearly with increasing temperature in this range and had the following values for the slopes: ΔC44/ΔT=−1.43 × 108 dyne cm−2 deg−1,ΔC′/ΔT=−1.23 × 108,ΔK−1/ΔT=−1.8 × 108.
The values of the elastic constants at room temperature (298°) were found to be: C44=0.2848; C′=0.234; and K−1=0.770, all expressed in units of 1012 dyne cm−2. A thermodynamic argument is used to separate the effects of the volume change through thermal expansion from the other effects of temperature on the elastic constants. This argument shows that the change with temperature cannot be explained solely in terms of the change in volume because there is an explicit dependence of the constants on temperature. This explicit dependence is different in both magnitude and direction for the constants C′ and C44.
Some Aspects of Fundamental Frequency and Envelope Amplitude as Related to the Emotional Content of Speech
Authors: Lieberman Philip , Michaels Sheldon B. 
Published: September 2005

Pitch pulses were electronically derived from the utterances of three male native speakers of American English who each read eight neutral test sentences in certain “emotional” modes, i.e., as a question, an objective statement, a fearful utterance, a happy utterance, etc. A fixed-vowel POVO-type synthesizer was excited by these pitch pulses. The pitch perturbations, or rapid variations in the fundamental excitation rate, could be smoothed out and the POVO could be amplitude-modulated with a signal derived from the original speech envelope amplitude.
Tapes were recorded and presented to separate groups of naive listeners who categorized the emotional modes in forced judgment tests. Results of the tests show that with unprocessed speech, the listeners were able to correctly identify the emotional content 85% of the time. When only pitch information was presented, correct identification was made 44% of the time. When amplitude information was added to the pitch information, the identification rose to 47%. Smoothing the pitch information with a 40-msec time constant reduced the identifications to 38%, while 100-msec smoothing reduced the identifications to 25%. A 120-cps monotone with amplitude information derived from the original speech envelope amplitude resulted in 14% identifications.
Solution of the Wave Equation in a Medium with a Particular Velocity Variation
Authors: Potter D. S. , Murphy S. R. 
Published: September 2005

The formal solution of the scalar wave equation is presented for a point source in a medium which is inhomogeneous one dimension with a particular sound-velocity dependence. This solution is another of the class of integrable solutions, based upon Bessel's equation, which can be expressed in closed form, allowing the use of available tables for numerical work. The particular sound velocity chosen, c = c0z(z2 − a2)−12, is interesting in that it corresponds in part to actual underwater measurements and that it yields a shadow zone.
In addition, an integral involving products of Bessel functions is reduced to a simple form, not found in the literature on Bessel functions.
Moments of the Output of Linear Random Systems
Authors: Bogdanoff J. L. , Kozin F. 
Published: September 2005

A method is presented for determining the differential equations of the output moments of a linear random system in which the coefficients are components of vector Markov processes. The method is based upon well-known results in applied stochastics. It appears considerably simpler than methods recently suggested for studying the behavior of linear random systems.
A stability criterion previously published is obtained with little effort. Reasons are presented for disagreeing with published results that mean motion of linear random systems with Gaussian parameter variations is not influenced by these variations.
Theory of Ultrasonic Delay Lines for Direct-Current Pulse Transmission
Authors: Onoe Morio 
Published: September 2005

A unified analysis of ultrasonic delay lines is presented with particular attention paid to the characteristics of direct-current pulse transmission. The analysis can be applied to any delay line, whether piezoelectric or magnetostrictive, regardless of whether the mode of transmission is longitudinal, shear, or torsional, as long as the motion is adequately described by the one-dimensional theory on which the equivalent circuits are based.
Characteristics in the time domain are obtained in terms of the time-shift operators of Laplace transform calculus. This makes it possible to easily obtain the output waveform for any arbitrary input. Three transducer configurations are discussed; namely, a line with transducers in the middle of the delay medium (Case A), a line with one of the transducers at the free end of the delay medium (Case B) and a line with transducers at both free ends of the delay medium (Case C).
The latter two configurations are especially useful for a delay line made of a ferrite or piezoelectric ceramic, both of which are available in limited length only due to manufacturing difficulties. Cascading of several pieces of material in order to obtain a longer delay than that which is available using a single piece is discussed. The effects of acoustic mismatching at bonding points on the signal-to-noise ratio and on the ringing in the output are presented.
Resolution of Pressure in Turbulence
Authors: Corcos G. M. 
Published: September 2005

The finite size of a transducer-sensing element limits its space resolution of a pressure field associated with a local turbulent flow. Such pressure fields are translated at a speed comparable to the characteristic velocity of the flow. Consequently, a lack of resolution in space causes an apparent inability to resolve in time. This problem—an example of the mapping of a random function of several variables by a linear operator—is examined here. With the help of a formalism which has been previously discussed and of some recent experimental information about the spatial structure of turbulent pressure fields in boundary layers, the mapping or distortion of statistical quantities associated with the second-order moments of the pressure field is given. The attenuation of the frequency spectral density and of the cross-spectral density is given explicitly in table form and in asymptotic form. The numerical results indicate that the attenuation caused by the finite size of transducers is generally more severe than previous computations had suggested, mainly because the lateral correlation of pressure is highly frequency-dependent, a typical turbulent pressure-wave component being inclined to the stream direction at roughly 45 degrees.
The results are applied to an evaluation of contemporary measurements of turbulent pressure fields in shear flows. It is shown that the transducer size used introduces undesirable large errors in these measurements, which lead to doubts even about the magnitude of the intensity of turbulent pressure fluctuations.
Asymptotic formulas for the attenuation of large transducers are given which yield estimates of the degree to which a flush-mounted sonar receiver immersed in a boundary layer is able to reject the background noise provided by turbulent pressure fluctuations.
Elastic Constants of Compound Semiconductors—ZnS, PbTe, GaSb
Authors: Einspruch Norman G. , Manning Robert J. 
Published: September 2005

The elastic constants of three compound semiconductors, ZnS, PbTe, and GaSb, were measured at 29°C using the ultrasonic pulse-echo technique. The constants are found to be
c 11 c12 c44
(in units of 1011 dyn cm−2)
ZnS 9.76 5.90 4.51
PbTe 10.72 0.768 1.300
GaSb 8.97 4.12 4.48.
These results are compared with previously reported measurements made by other techniques.
Vibrations of Longitudinally Polarized Ferroelectric Cylindrical Tubes
Authors: Martin Gordon E. 
Published: September 2005

The theory of vibrations of longitudinally polarized, thin-wall ferroelectric ceramic tubes is derived including the lateral influence on the longitudinal vibrations. Tenors are utilized throughout the derivation, but a summary of the results is presented in the commonly used matrix forms.
The equations of motion and the equations of state for materials possessing transverse isotropy are transformed to cylindrical coordinates. A new electromechanical equivalent circuit is obtained which is similar to that of Mason, except that the latter ignores lateral effects. The new theory explains experimental results which would be considered anomolous in the older one-dimensional theory.
Synthesis of Dispersive Delay Characteristics by Thickness Tapering in Ultrasonic Strip Delay Lines
Authors: Fitch Arthur H. 
Published: September 2005

Tapering the thickness of a dispersive strip delay line operating in the first longitudinal mode can yield a variety of delay characteristics unobtainable with strips of uniform thickness. A strip whose thickness varies in some manner along its length may be thought of as a number of strip sections of constant thickness in series. The additive delay of these series sections can produce an over-all delay characteristic completely different in form from the delay characteristics of the individual sections. A design procedure involving the methods of linear programming has been developed which allows a unique determination of the taper required to produce a given delay function.
As a basis for comparison, the delay of a strip delay line of constant thickness departs from a straight-line characteristic by 1.5% of the nominal delay over a fractional frequency bandwidth of 15%. A tapered strip line designed for the same nominal delay and the same delay slope departs from linearity by only 0.5% over a 25% band. A tapered line designed to approximate an increasing parabolic delay characteristic exhibits a delay deviation of only 0.5% over a frequency band of 13%. An “image” line was fabricated having a decreasing parabolic delay characteristic approximating the mirror image of the increasing parabolic characteristic mentioned above. Although most of the applications of delay synthesis have employed the first longitudinal plate mode, the design procedure has also been applied to shear modes in a strip. For delay lines having nominal delays of 1000 μsec, typical insertion losses are 16 to 25 dB, with discrimination against unwanted signals of 35 to 40 dB.
Precision of Oceanographic Data for Sound-Speed Calculations
Authors: Fofonoff N. P. 
Published: September 2005

The precision of sound speeds calculated from oceanographic data, consisting of measurements of temperature and salinity at various depths, depends on systematic errors of the empirical formula relating sound speed to the oceanographic variables and on the errors of the measured variables. Estimates of precision, defined as twice the standard deviation, range from 0.021°–0.025°C for temperature, 0.016‰–0.072‰ for salinities determined by titration, and 7–12 m for depths to 1000 m. Systematic errors of the sound-speed formula are estimated to be about 0.5 m/sec.
In a homogeneous layer of the ocean, the errors of measurement of temperature and salinity limit the precision of sound speed to 0.12 m/sec. In a stratified layer, the precision less (larger standard deviation) because of the uncertainty in the depth determination.
Mechanical Input Admittance of Ultrasonic Delay Lines Operating in Torsional or Shear Modes
Authors: Onoe Morio 
Published: September 2005

The mechanical input admittance at the end face of an ultrasonic delay line operating in torsional modes for a rod or shear modes for a plate is analyzed. The analysis is based on the facts that SH waves in a plate constitute a Fourier series and torsional waves in a rod constitute a Dini series, and consequently any stress distribution on the end face can be expanded in terms of these waves. It is shown that modes below cutoff contribute to the susceptance, and modes above cutoff contribute to the conductance. Three transducer configurations are discussed: namely, a single transducer for exciting symmetric modes in a plate, two push-pull transducers for exciting antisymmetric modes in a plate, and a hollow coaxial transducer for exciting torsional modes in a rod. Modes below cutoff decay exponentially along the direction of propagation. The distance from the end face at which these modes have significant effects is discussed. As the frequency becomes successively higher than cutoff frequencies, successively more modes become propagating. The amplitude distribution among these propagating modes is also discussed.
A transducer which covers the whole cross section can excite the fundamental nondispersive mode in plates and rods without generating higher modes. Hence, this configuration is recommended for delay line design in order to avoid possible complications due to higher modes in the delay line characteristics.
Optimization of the Mass Distribution and the Air Spaces in Multiple-Element Soundproofing Structures
Authors: Mangiarotty R. A. 
Published: September 2005

A method is evolved for predicting the transmission loss of soundproofing multiple-element configurations containing any number of elements. The optimum distribution of mass between the impervious elements (fuselage skin panel, blanket septa, trim panel) is determined for a general theoretical configuration and for a typical aircraft structure. The theoretical improvement obtained by mass distribution optimization (approximately uniform distribution between the impervious elements) is about 3 to 6 dB in the low frequencies (below 500 cps) and 8 to 14 dB in the speech interference range (600 to 4800 cps).
It is shown that a large increase in air spaces between elements is required to obtain only about 8- to 10-dB improvement (in theory), neglecting contact flanking paths between the elements. Also, replacing air spaces with acoustical blankets produces small improvements (2 to 8 dB) at the cost of possible structural flanking transmission between the elements.
It is also shown that covering a hard terminating trim panel with an acoustical blanket increases the overall transmission loss by about 2 to 6 dB in the 300- to 4800-cps frequency region.
Finally, it is shown that reducing the ambient pressure in a fuselage reduces the sound attenuation properties of soundproofing, viz., the decrease in transmission loss due to pressurizing an aircraft to an equivalent altitude of 8000 ft is about 3 to 6 dB.
Empirical Evidence for Nonlinearity and Directions for Future Work
Authors: Lyon Richard H. 
Published: September 2005

The effects of nonlinearity in several clamped clamped beam vibration problems are reviewed. Possible effects are: jump or instability phenomena, amplitude-limiting effects, and distortion of probability densities. Studies of prototype panel frame structures show similar behavior. The necessity for extending these efforts to built-up structures is emphasized. Also, estimates for the onset of nonlinearity based on two simple models are made to show how one can be guided in experimental design by quantitative-empirical considerations.
Some theoretical techniques are appraised for their applicability to the structures problem. In particular, two approximation methods are singled out for detailed comment. Finally, the possibilities of a more creative use of experimental analysis and a closer tie between theoretical and experimental effort in structures research are explored.
Measurement of the Adiabatic Elastic Moduli of Single Crystal Alpha Uranium
Authors: Fisher E. S. , McSkimin H. J. 
Published: September 2005

The adiabatic elastic moduli at 25°C for single crystal alpha uranium are reported here as derived from ultrasonic wave velocities in the frequency range 30 to 180 mcps. Seven specimens grown by a grain coarsening method [E. S. Fisher, J. Metals 9, 882 (1957)] were used, with thickness dimensions of 2 to 4 mm and lateral dimensions of approximately 5 mm. Even though the sizes involved were small, the precision obtained was good, as evidenced by the numerous cross-checks afforded by the twenty-one free-space velocities determined. The method of measurement is briefly reviewed [refer to IRE Trans. on Ultrasonics Eng. PGUE-5, 25 (1957)], and the correlation of data to minimize uncertainties is discussed. In units of 1012 dynes/cm2 the elastic stiffness moduli are as follows (based on a density of 19.04 g/cc):
C 11  = 2.1474 ± 0.14% , C12 = 0.4649 ± 0.6%,
C 13  = 0.2177 ± 1.5% , C22 = 1.9857 ± 0.14%,
C 23  = 1.0791 ± 0.7% , C33 = 2.6711 ± 0.14%,
C 44  = 1.2444 ± 0.10% , C55 = 0.7342 ± 0.10%,
C 66  = 0.7433 ± 0.10% .
(Part of this research was carried out under the auspices of the U. S. Atomic Energy Commission.)
Assembly of Cyclic Enterobacterial Common Antigen in
Escherichia coli
K-12
Authors: Kajimura Junko , Rahman Arifur , Rick Paul D. 
Published: September 2005

ABSTRACT

We describe here the purification and quantification of a water-soluble cyclic form of enterobacterial common antigen (ECA
CYC
) from
Escherichia coli
K-12 as well as information regarding its subcellular location and the genetic loci involved in its assembly. Structural characterization of purified ECA
CYC
molecules obtained from
E. coli
K-12 revealed that they uniformly contained four trisaccharide repeat units, and they were substituted with from zero to four
O
-acetyl groups. Cells from overnight cultures contained approximately 2 μg ECA
CYC
per milligram (dry weight), and cell fractionation studies revealed that these molecules were localized exclusively in the periplasm. The synthesis and assembly of ECA
CYC
were found to require the
wzxE
and
wzyE
genes of the
wec
gene cluster. These genes encode proteins involved in the transmembrane translocation of undecaprenylpyrophosphate-linked ECA trisaccharide repeat units and the polymerization of trisaccharide repeat units, respectively. Surprisingly, synthesis of ECA
CYC
was dependent on the
wzzE
gene, which is required for the modulation of the polysaccharide chain lengths of phosphoglyceride-linked ECA (ECA
PG
). The presence of ECA
CYC
in extracts of several other gram-negative enteric organisms was also demonstrated; however, it was not detected in cell extracts of
Pseudomonas aeruginosa
. These data suggest that in addition to ECA
PG
, ECA
CYC
may be synthesized in many, if not all, members of the
Enterobacteriaceae
.