Showing papers in "Journal of Physics D in 1973"
TL;DR: In this article, the authors studied the dependence of debonding stress and pull-out stress on the embedded length of a stainless steel wire embedded in an epoxy resin and found that the effect of wire contraction on the friction process was confirmed by using different initial wire tensions.
Abstract: The extraction of a stainless steel wire embedded in an epoxy resin has been studied as a function of the embedded length. The models developed to elucidate the dependence of the debonding stress and the pull-out stress on the embedded length are applied successfully to the experimental results. The nonlinear variation of the debonding stress with the embedded length is caused by the distribution of shear stress along the wire. The variation of pull-out stress with embedded length is caused by the decrease of the frictional stress due to the Poisson contraction of the wire under tensile stress. The effect of wire contraction on the friction process was confirmed by using different initial wire tensions. The residual compressive stress at the interface due to resin shrinkage and the coefficient of friction were determined from the analysis of the pull-out process.
258 citations
TL;DR: In this paper, the amplitude and phase from the intensity distribution of an electron micrograph is estimated using the relative defocus between micrographs, and the procedure is valid both in bright field and dark field microscopy for any specified coherence of the electron source.
Abstract: A method is given for the evaluation, in transmission electron microscopy, of the amplitude and phase from the intensity distribution of an electron micrograph. The method requires a minimum of two micrographs taken under different defocus conditions. The iterative scheme requires only the relative defocus between micrographs, and the procedure is valid both in bright-field and dark-field microscopy for any specified coherence of the electron source. Assumptions on the scattering properties of the specimen, such as the weak-phase-weak-amplitude object, are not required. For a complete determination of the amplitude-phase distribution for electron transmission through the specimen, the electron micrograph must be corrected for the effect of lens aberrations and defocusing to give the electron wavefunction immediately after transmission; only in the case of a weak-phase object can this wavefunction be directly related to the projected potential distribution in the object. Inelastic electron scattering is explicitly omitted from the analysis presented.
238 citations
TL;DR: In this paper, it has been found that it is possible to detect slackness at an interface, in situations where this slackness is not severe enough to amount to an actual unbond.
Abstract: Flaws are commonly detected by their ability to reflect a burst of ultrasound back to a piezoelectric transducer, and a flaw is taken to be found if an ultrasonic reflection is detected. In this form, relying simply upon the existence or otherwise of a signal, the pulse-echo technique is not suited to the detection of weak bonding between an adherend and an adhesive, because both perfect and imperfect interfaces between dissimilar materials always reflect ultrasound. In 1971 Rolls-Royce sponsored an investigation into a highly developed form of pulse-echo technique, in which all the information from the reflected pulse is used, expressed in terms of accurate amplitude and phase measurements. It has been found possible to detect `slackness' at an interface, in situations where this slackness is not severe enough to amount to an actual unbond.
231 citations
TL;DR: In this article, the contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson.
Abstract: The contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson. The physical significance of the differences between the two theories are discussed; in particular, the influence of a distribution of asperity curvatures is revealed. It is suggested that the simple model of Greenwood and Williamson can underestimate both the pressures at the true areas of contact and the probability of plastic flow.
230 citations
TL;DR: In this article, the thermal expansion of vitreous silica is shown to be particularly sensitive to thermal history values given for the linear coefficient α were determined relative to copper, and existing reference data for copper are discussed.
Abstract: Between 30 and 290 K the thermal expansion of vitreous silica is shown to be particularly sensitive to thermal history Values given for the linear coefficient α were determined relative to copper, and existing reference data for copper are discussed α for silicon has also been measured relative to copper from 55 K to room temperature Values of α at 283 K are reported for a number of samples of copper, and for Ag, Au, Al, Pt, Pd, MgO, NaCl and CaF2
183 citations
TL;DR: In this paper, the authors considered a mixture of conducting particles dispersed in an insulating medium, and the electrical conduction which can occur by particles touching is related to the proportion of conducting material present in the mix, and its conductivity.
Abstract: Mixtures consisting of conducting particles dispersed in an insulating medium are considered, and the electrical conduction which can occur by particles touching is related to the proportion of conducting material present in the mix, and its conductivity. It is found that limiting values of conduction can be obtained for a random dispersion and also for the situation where the conducting material lies in interconnecting channels, both systems being observed in practical mixtures. The way in which the basic relationship can be modified by particle size, shape and orientation, contact resistance and particle packing is also considered.
173 citations
TL;DR: In this article, an iterative method for determining the amplitude and phase from the image intensity recorded in optical systems was proposed, which requires two images recorded at different lens defocus values, is tested with simulated data subject to error arising from the photographic recording of the image.
Abstract: An evaluation is made of an iterative method for determining the amplitude and phase from the image intensity recorded in optical systems. The method, which requires two images recorded at different lens defocus values, is tested with simulated data subject to error arising from the photographic recording of the image. In the case of error-free data, the solution for the phase distribution appears to be indeterminate to within a constant. The results for photographic noise levels of up to 20% of the maximum image intensity reflect the small effect of error on the calculated phase distribution. The calculation of phase distributions for both symmetric and asymmetric amplitude-phase distributions shows that the use of two images, taken at defocus values differing by about 100 nm in electron optics and about 1 mm in optics (depending on the numerical aperture of the objective lens), may be used to determine the complex object wave-function in both dark-field and bright-field optics.
120 citations
TL;DR: In this paper, an apparatus for measuring the flexural damping and dynamic Young's modulus of beam specimens at stress levels up to 200 MN m−2 was described, where symmetric free-free flexural modes of vibration were excited by a coil/magnet pair, the coil being attached to the midpoint of the beam.
Abstract: An apparatus is described which is suitable for measuring the flexural damping and dynamic Young's modulus of beam specimens at stress levels up to 200 MN m−2. Symmetric free-free flexural modes of vibration are excited by a coil/magnet pair, the coil being attached to the midpoint of the beam. Extraneous sources of damping have been reduced to a low level despite the difficulties of producing high-amplitude vibration. Low-damping specimens must be tested in vacuo (05 Torr was usually sufficient) if the effects of air damping are not to be significant. Specific damping capacities from 01 to 50% can be accurately measured over a frequency range of 100 to 800 Hz and a temperature range -50 to +200°C.
105 citations
TL;DR: In this article, a theory for the effect of shrinkage stresses on the peel strength of a joint between rubber and glass is developed, which suggests that shrinkage weakens the joint, the weakening becoming more noticeable with rise in shrinkage strain and rubber film thickness.
Abstract: A theory for the effect of shrinkage stresses on the peel strength of a joint between rubber and glass is developed. The theory suggests that shrinkage weakens the joint, the weakening becoming more noticeable with rise in shrinkage strain and rubber film thickness. Peeling experiments on a rubber-glass bond verify the theory and justify a discussion of shrinkage in butt joints.
86 citations
TL;DR: The chemical nature and physical origin of the afterpulses found in RCA 8850 and 8852 photomultipliers have been investigated as discussed by the authors, and it has been confirmed that the increase in the number of afterPulses with time was the result of diffusion of helium through the tube envelope.
Abstract: The chemical nature and physical origin of the afterpulses found in RCA 8850 and 8852 photomultipliers have been investigated. It has been confirmed that the increase in the number of afterpulses with time was the result of diffusion of helium through the tube envelope. It has also been shown that afterpulses may originate throughout the photomultiplier, and the factors which influence their formation are discussed.
73 citations
TL;DR: In this article, a full spherical retarding field energy analyser with three grids was made to measure the total secondary electron yield σ, the backscattering coefficient η, and the secondary electron spectrum N(E) as a function of angle of incidence and primary energy in UHV.
Abstract: A full spherical retarding-field energy analyser with three grids was made to measure the total secondary electron yield σ, the backscattering coefficient η, and the secondary electron spectrum N(E) as a function of angle of incidence and primary energy in UHV. The instrumental effects of the grid meshes in the measurement of N(E) were minimized by using the sample-bias-modulation technique. The values of σ and η for polycrystalline copper were found to be rather higher than previously published values. The N(E) curves are almost independent of the angle of incidence (θ) between θ=0° and 40°. The halfwidth of N(E) increases as the primary energy is reduced. These suggest that in metals the electron-electron interaction is dominant. Also, the dependence of N(E) on primary energy is believed to be caused by variations in both the excitation depth and the initial energy distribution of internal secondaries.
TL;DR: In this paper, the elastic constants and thermal expansion of single-crystal CdTe have been measured in the temperature range 42-300 K. An anomaly in both parameters is observed, which has hitherto not been reported, and is tentatively attributed to a change in ionicity.
Abstract: The elastic constants and thermal expansion of single-crystal CdTe have been measured in the temperature range 42-300 K. The values of elastic constants obtained at 298 K were C11=538×1010 N m−2, C12=374×1010 N m−2 and C44=2018×1010 N m−2. Their temperature variation is in good agreement with Vekilov and Rusakov's (1971) values and the temperature dependence of the thermal expansion is similar to the other measurements in the literature. An anomaly in both parameters is observed, which has hitherto not been reported, and is tentatively attributed to a change in ionicity. The Debye temperature at 0 K is calculated from the elastic constants and a value of 1627 K obtained.
TL;DR: In this article, it is shown how an inaccurate alignment of a differential laser anemometer may cause a significant broadening of the Doppler spectrum, due to gradients in the interference pattern in the measuring volume.
Abstract: It is shown how an inaccurate alignment of a differential laser anemometer may cause a significant broadening of the Doppler spectrum. The reason is the appearance of gradients in the interference pattern in the measuring volume. The phenomenon was investigated theoretically, and a method to measure these gradients is presented.
TL;DR: In this article, it was shown that the direction in which the cube surface has been polished affects both the magnitude and the symmetry of the friction, which implies that the friction arises from a ratchet-type mechanism.
Abstract: The friction has been measured as a function of the applied load, the direction of sliding and the degree of lubrication of the surface. It is found that the direction in which the cube surface has been polished affects both the magnitude and the symmetry of the friction. Our results imply, in contrast to earlier work, that the friction arises from a ratchet-type mechanism, and that polished diamond surfaces have unusual properties.
TL;DR: In a TIG welding arc, less than half of the heat generated by the workpiece (anode) is transferred to the anode by electron and space charge effects at the surface as mentioned in this paper.
Abstract: Less than half of the heat generated in a TIG welding arc (typically 1600 W at 16 V, 100 A) is transferred to the workpiece (anode). Convection, conduction and radiation from the gas occur over the whole of the arc region, but they represent relatively minor contributions to the total heat balance. The principal anode heating and cooling mechanisms involve electron and space-charge effects at the surface. These electron effects are evident in the workfunction (typically 45 V) which is dominant, the electron thermal energy transfer (1 V) and the anode fall (2 V), and they are concentrated in the restricted anode current spot so they may be considered as a localized heat source. Evaporation is most intense from the anode spot region and carries away some heat. However, most of the vapour condenses on the cooler, outer regions of the anode surface covered by the arc. In this way, heat is redistributed and diffused over a wider area. Vaporization effects explain the differences between previous measurements with cooled copper anodes (in which 80% of the arc power is transferred to the metal) and ones with practical, molten-steel welds (less than 50% heat transfer).
TL;DR: In this paper, an exponential dependence of the current on the square root of the applied voltage is reported under fast transient conditions (80 μs-2 ms), and the coefficient of this dependence is found to be temperature and time-independent over the range 150-275°C.
Abstract: Electrical conduction in `Kapton' polyimide film is studied under both transient and steady-state conditions. An exponential dependence of the current on the square root of the applied voltage is reported under fast transient conditions (80 μs-2 ms). The coefficient of this dependence is found to be temperature- and time-independent over the range 150-275°C. The DC conduction shows a similar field dependence, but the coefficient is expressed as two factors, one of which is temperature-independent. Evidence is presented to suggest that the DC conduction could be associated with a mechanism of thermally assisted tunnelling, and that the transient conduction could involve tunnelling of electrons between conduction-band-tail states in the insulator.
TL;DR: In this paper, an electrostatic probe is used to measure the currentvoltage of a high-current (100 A), high-pressure (1 bar), DC argon (TIG) welding arc.
Abstract: The electrostatic probe is an attractive diagnostic tool for DC welding arcs. The current-voltage characteristic of such a probe in a high-current (100 A), high-pressure (1 bar), DC argon (TIG) welding arc is found to give a very flat ion saturation region. Sheath thicknesses are estimated to be much smaller than 1 ?m, ie less than the mean free path, so that conventional collisionless probe theory should be applicable - in contrast to the flame plasmas dealt with by Thomas (1969) and others. By using an Abel inversion technique the measured probe current can be converted to a radial distribution of current. The temperature variation across the arc can then be derived from this current variation. By measuring the radial temperature profile at several points along the length of the arc column, a complete isothermal map of the TIG arc has been obtained which is important for basic calculations of energy transfer.
TL;DR: In this article, the amplitude-phase distribution of an image from two image intensity distributions recorded at two different lens defocus values is examined, and the effects of various sources of error on the solution for the phase distribution are examined, namely, a background signal superimposed on the image intensity, a mismatching of the two images and an error in determining the defocus difference between the two views.
Abstract: In the evaluation of an iterative scheme that determines the amplitude-phase distribution of an image from two image intensity distributions recorded at two different lens defocus values, the effects of various sources of error on the solution for the phase distribution are examined, namely, a background signal superimposed on the image intensity, a mismatching of the two images and an error in determining the defocus difference between the two images. In electron optics, a background intensity, arising from (say) inelastic electron scattering, corresponding to 10% of the maximum image intensity has a significant effect on the calculated phase distribution. In high-resolution electron microscopy, achieving a potential image resolution of 01-03 nm, a mismatching of the two images by 01 nm is acceptable, corresponding to a misalignment of the two electron micrographs by 50 μm at an electron-optical magnification of 500 000; and a defocus error of 10 nm, in a total defocus difference of 100 nm between the two images, does not severely distort the solution for the phase distribution. The combined effect of photographic noise (10-20% of the maximum intensity), mismatching (01 nm), defocus error (10 nm) and a background (6% of the maximum intensity) on the calculated phase distribution gives an indication of the maximum error that can be tolerated in an experimental test of the method. The magnitude of the maximum error that can be tolerated may be scaled to the resolution required in the phase solution and the wavelength of the radiation used; in optics with a potential image resolution of 10 μm, a mismatching of images by 5-10 μm (at unit magnification or 05-10 mm at an optical magnification of 100) is acceptable and a corresponding defocus error of 100 μm for a defocus difference of 1 mm (depending on the numerical aperture of the objective lens).
TL;DR: In this paper, a theory for fitting weighted complex data to a given function is given, illustrated with two examples from the field of dielectrics: one for real data and the other for complex data.
Abstract: A theory is given for fitting weighted complex data to a given function. The method is illustrated with two examples from the field of dielectrics: one for real data and the other for complex data. It is shown that the inclusion of weighting factors alters the parameter estimates as well as reducing the confidence intervals.
TL;DR: In this article, anodic tantalum oxide films of thicknesses from 160 to 510 nm with counter electrodes of aluminium have been studied under steady and step-function transient voltage conditions and the peaked form of the transient current with this polarity confirms that space charge limitation is occurring and gives a direct measure of carrier mobility strongly influenced by traps.
Abstract: Electrical conduction in anodic tantalum oxide films of thicknesses from 160 to 510 nm with counter electrodes of aluminium have been studied under steady and step-function transient voltage conditions. The system is strongly rectifying; and in forward bias with tantalum negative, the current is space-charge-limited with clear indications of progressive filling of deep traps finally giving way to a shallow-trap conduction process for which the effective carrier (electron) mobility is only 10?1?6 m2 V?1 s?1. The peaked form of the transient current with this polarity confirms that space-charge limitation is occurring and gives a direct measure of carrier mobility strongly influenced by traps and in agreement with the above. In reverse bias, Schottky-type, field-enhanced emission from the aluminium cathode is believed to occur with a workfunction of 0?44 eV, but the current is limited to low values by an aluminium-oxide interfacial barrier. The transient current decreases monotonically with this polarity and is taken as evidence for trap emptying. An energy band model for the oxide is deduced with a band of deep trapping levels separated from an effective hopping conduction band.
TL;DR: In this article, the primary avalanches transform to a bright luminous layer which develops toward the anode first slowly (ν approximate 1·5 ν−, where ν − is the drift velocity of electrons), then very fast (ν>10−).
Abstract: Experiments on pulsed N2 discharges at high overvoltage in a homogeneous field are described. Former investigations by different authors revealed that at high overvoltage a filamentary discharge develops according to the streamer mechanism. The number of primary electrons released at the cathode was low in these experiments. The discharges described here are initiated by a very high number (approximate 108) of primary electrons distributed uniformly over the cathode surface. Optical investigations with streak camera and image intensifier resolving the development in space and time show that the primary avalanches transform to a bright luminous layer which develops toward the anode first slowly (ν approximate 1·5 ν−, where ν− is the drift velocity of electrons), then very fast (ν>10ν−). Later a second luminous layer arises nearer to the cathode, spreading in both directions. The layers are homogeneous over a large area. In contrast to the single-streamer development the field distortions by space charge can be calculated easily using a one-dimensional approximation. Preliminary calculations show that the cathode-directed development is mostly due to secondary electrons from the cathode, while the fast development toward the anode is caused by a far-reaching process, probably gas-ionizing radiation, generating new electrons in the neutral gas.
TL;DR: In this paper, the conductivity of polyethylene films of thickness 25, 50 and 75 μm was investigated and the results were applied to a model proposed by Adachi et al. and good agreement was found between experimental results and those predicted by their model.
Abstract: DC conductivity measurements were carried out on low-density polyethylene films of thickness 25, 50 and 75 μm. The material showed non-ohmic conduction on application of high electric fields in the range 1 × 107 to 3 × 107 Vm−1. The results were applied to a model proposed by Adachi et al (1971) and good agreement was found between experimental results and those predicted by their model. The polyethylene was also treated with hexane, following the same procedure as Partridge (1967), and it was observed, as with Partridge, that the conductivity was reduced by two orders of magnitude.
TL;DR: In this paper, the design and operation of a simple, inexpensive, multiple anode-hollow cathode laser tube for CW helium-metal vapour laser systems are presented.
Abstract: Details of the design and operation of a simple, inexpensive, multiple anode-hollow cathode laser tube for CW helium-metal vapour laser systems are presented. The device is of metal construction and the component sections are connected by ordinary O ring couplings. To preserve the cleanliness of the system, helium from a high-pressure cylinder is slowly flushed through the tube. We have observed CW laser oscillation on a total of 39 lines in four helium-metal vapour systems (He-Cd, He-Zn, He-Se, He-I2) at wavelengths ranging from the near ultraviolet to the infrared, and output powers up to 25 mW/line. Operating characteristics of the laser are discussed for each system.
TL;DR: In this article, the intensity of dielectric absorption is used as a monitor of the state of aggregation of the Mg2+-vacancy pairs, and it is shown that one of the factors determining the heights of peaks 2 and 3 is the concentration of dipoles in the crystal at the time of irradiation.
Abstract: When LiF crystals containing a low concentration of Mg2+ ions are irradiated with γ-rays and then heated, five glow peaks may be observed. The intensity of dielectric absorption is used as a monitor of the state of aggregation of the Mg2+-vacancy pairs. It is shown that one of the factors determining the heights of peaks 2 and 3 is the concentration of dipoles in the crystal at the time of irradiation; those Mg2+-vacancy pairs present in trimers and larger aggregates make no contribution to the height of these peaks. Both dipoles and trimers contribute to the traps responsible for peaks 4 and 5, but aggregates containing more than three Mg2+-vacancy pairs do not contribute. Previous work based on the assumption of a direct proportionality between dipole concentration and the height of peak 2 is invalid.
TL;DR: In this paper, a mathematical model of the gas atomization of a liquid is developed, in which the liquid is allowed to have infinite depth, taking into account both the compressibility of gas and the viscosity of the liquid, enabling a prediction to be made of the expected drop size in the spray formed when a gas flows over a liquid.
Abstract: A mathematical model of the gas atomization of a liquid is developed. This model, in which the liquid is allowed to have infinite depth, takes into account both the compressibility of the gas and the viscosity of the liquid, enabling a prediction to be made of the expected drop size in the spray formed when a gas flows over a liquid. It gives good results for the air atomization of water and an order-of-magnitude agreement for that of molten metals. A universal curve is constructed for molten metals such that the predicted size of the most frequently occurring drop size can be found by evaluating a single formula. The effect of allowing the liquid to have finite depth is investigated in two cases of interest.
TL;DR: In this paper, a carbon-fibre field-emission source with a brightness of 1012 A sr−1 m−2 and currents in excess of 200 μA s−1 at voltages of 2-3 kV is described.
Abstract: The development is described of a carbon-fibre field-emission source with a brightness of 1012 A sr−1 m−2 and currents in excess of 200 μA sr−1 at voltages of 2-3 kV. The source can be run continuously in ambient gas pressures two decades higher than tungsten field emitters at the same current fluctuation level of 2-3%. The source makes possible the operation of field-emission electron guns in conventional unbaked vacuum systems.
TL;DR: In this article, the breakdown of gases by short (typically sub-nanosecond) laser pulses when the two dominant mechanisms governing the plasma growth are multiphoton and cascade ionization is treated theoretically.
Abstract: The breakdown of gases by short (typically sub-nanosecond) laser pulses when the two dominant mechanisms governing the plasma growth are multiphoton and cascade ionization is treated theoretically. It is shown that two important pressure r?gimes result: a low-pressure r?gime where the breakdown is governed solely by the multiphoton ionization process; and a high-pressure r?gime where the expression for threshold breakdown intensity involves both ionization processes as well as the effect of impurities in the gas. The predictions of the theory are compared with published experimental data for ruby and Nd3+ laser pulses. Good agreement is obtained in the case of ruby radiation, and a possible explanation of deviation from the experimental data obtained using a Nd3+ laser is offered.
TL;DR: In this article, the impact resistance of uniaxial fiber-reinforced epoxy resin composites has been investigated in both untreated and surface-treated conditions, and it has been shown that the fibre-matrix interface is strongest when the type II and III treated fibres are employed and weakest for the type I untreated fibres.
Abstract: Uniaxial fibre-reinforced epoxy resin composites have been produced containing up to Vf=08 of type I, II, III and IV carbon fibres in both untreated and surface-treated conditions. Their mechanical properties have been determined, and it has been shown that the fibre-matrix interface is strongest when the type II and III treated fibres are employed and weakest for the type I untreated fibres. The strength and stiffness of the composites approach that predicted by a rule of mixtures law at low Vf, but tend to fall below this when Vf>06. This fall off is greater in the case of composites of low fibre-matrix interface strength. The impact resistance (unnotched) is related to the strain energy potential of the fibre, Vf, and to a lesser extent to the fibre-matrix interface strength. A parameter U*=σf2Vf/Ef is proposed as an indicator of impact resistance performance. The principal effect of the interface strength is to modify the mode of failure. At high levels of strength the failure is brittle and relatively little energy is absorbed. At low levels of strength a multiple delamination occurs, energy absorption is about three times as high as in the brittle case, but extensive disintegration of the specimen occurs. At intermediate values of interface strength a progressive failure occurs which appears to be the best practical compromise; energy absorption is relatively high and disintegration is avoided. The composites having the best impact resistance were those containing 06 Vf type II or III untreated fibre. These gave impact energies of similar 100 kJ m−2 and had interlaminar shear strengths of 50-60 MN m−2.
TL;DR: In this paper, a segmented model of a domain wall structure is discussed, which enables an accurate theoretical analysis to be made of the motion of domain walls severely distorted by an inhomogeneous eddy current field.
Abstract: A segmented model domain wall structure is discussed which enables an accurate theoretical analysis to be made of the motion of domain walls severely distorted by an inhomogeneous eddy current field. Methods are developed for determining the wall profile and eddy current field at successive phases of the motion, when either the applied field or the flux is a prescribed function of time. These techniques are applied to a detailed study of an isolated domain wall driven so as to generate sinusoidal flux variations. Severe wall bowing is found to reduce the relative eddy current drag very roughly as the cube root of the frequency and the square root of the amplitude. At low flux amplitudes, asymptotic agreement is found with an independent exact theory of the infinitesimal motion of a continuous quasi-plane wall. The segmented model, adapted to include interactions between walls by eddy current overlap and actual merging of neighbouring walls into cylindrical domains, is also applied to the study of saturation sinusoidal induction. Comparison with experiment is made by simulating the motion of a pair of domain walls observed by Helmiss (1969) in a detailed study of flux reversal in a single-crystal `picture- frame' specimen of 3·5% silicon-iron. Good agreement is found between the simulated eddy current losses and those reported by Helmiss. Reasonable concordance of calculated values of the surface wall velocity with those observed by Kerr magneto-optic methods is also obtained.
TL;DR: In this paper, a new method of determining absolute pressure based on the simultaneous measurement of length and ultrasonic transit times was proposed, which was used to determine the transition pressure of pure mercury at 0 °C at 75712±16 bar.
Abstract: This is a preliminary description of a new method of determining absolute pressure which is based on the simultaneous measurement of length and ultrasonic transit times. This method has been used to determine the transition pressure of pure mercury at 0 °C at 75712±16 bar. It is particularly advantageous to use for calibrating secondary gauges such as manganin gauges inasmuch as it gives a highly accurate measurement of nonlinearities in such secondary gauges. The gauge calibrated in the present study reaches a maximum deviation from linearity of −116 bar at a pressure midway between atmospheric pressure and the 0 °C mercury melting pressure.