Showing papers on "Impulse (physics) published in 1971"
01 Sep 1971
TL;DR: In this paper, a numerical method using impulse analysis of a transmission-line matrix is introduced and used to obtain wave-impedance values in a waveguide, demonstrated by applying it to the scattering caused by a wave-guide bifurcation.
Abstract: A numerical method using impulse analysis of a transmission-line matrix is introduced and used to obtain wave-impedance values in a waveguide. The method is demonstrated by applying it to the scattering caused by a waveguide bifurcation.
605 citations
01 Jan 1971
TL;DR: In this paper, conduction and absorption-current measurements up to about half the breakdown field have given clear evidence of space charge effects in polythene, and the apparent intrinsic electric strength under various modes of stressing was obtained from measurements of the apparent ‘intrinsic’ electric strength.
Abstract: There has been speculation in the past about the extent to which space charge formed by the flow of prebreakdown current affects the electric strength of polythene In the present work, conduction and absorption-current measurements up to about half the breakdown field have given clear evidence of space-charge effects Further evidence was obtained from measurements of the apparent ‘intrinsic’ electric strength under various modes of stressing It was found that the electric strength of polythene measured with direct voltage below about 30°C exceeded the corresponding value measured with impulse voltages by up to about 25% The impulse electric strength could be increased to equal the direct voltage by prestressing each specimen for 4min with direct voltage of the same polarity as the impulse voltage However, when the impulse was of opposite polarity to the direct prestressing voltage, the electric strength decreased with increase in the prestressing field The effect was dramatic, for the impulse electric strength changed from the normal value of about 6MV cm−1 to less than 2MV cm−1 as the prestressing field was increased to about 75% of the electric stength measured with direct voltage Experiments in which the breakdown impulse was applied some time after removal of the prestressing field showed that the impulse electric strength at 20°C recovered in about 10−2s to the value obtained with impulses without prestressing Thus the prestressing caused no permanent damage The observed effects are attributed to space-charge injection from the electrodes The observations are not consistent with the concept that breakdown occurs when the field at a point within the specimen exceeds a critical value, the intrinsic electric strength of polythene
163 citations
TL;DR: In this article, the reciprocity theorem of Helmholtz is extended to the clear turbulent atmosphere and two impulse responses (Green's functions) are defined to characterize optical propagation in opposite directions between two parallel planar apertures separated by the turbulent atmosphere.
Abstract: The reciprocity theorem of Helmholtz is extended to the clear turbulent atmosphere. Two impulse responses (Green’s functions) are defined to characterize optical propagation in opposite directions between two parallel planar apertures separated by the turbulent atmosphere. It is shown that these impulse responses satisfy the same reciprocity condition as the free-space impulse responses do. This result underlies recent studies of adaptive communication systems for the turbulent channel.
131 citations
59 citations
36 citations
Patent•
08 Jan 1971
TL;DR: A pacemaker has an output control circuit which is adapted when activated to control the produced pace impulses in such a manner that the amplitude of each impulse is slightly less than that of the preceding impulse as discussed by the authors.
Abstract: A pacemaker having an output control circuit which is adapted when activated to control the produced pace impulses in such a manner that the amplitude of each impulse is slightly less than that of the preceding impulse. The control circuit can be activated and deactivated from outside, either by suitable hospital equipment or manually by a surgeon. It permits the threshold value of the heart to be determined without surgical operation by ascertaining the smallest pace impulse that causes heart contraction.
34 citations
TL;DR: Fluctuations in the discharge of impulses were studied in eccentric cells of the compound eye of the horseshoe crab, Limulus polyphemus to present a theory which accounts for the variability in the response of the eccentric cell to light.
Abstract: Fluctuations in the discharge of impulses were studied in eccentric cells of the compound eye of the horseshoe crab, Limulus polyphemus. A theory is presented which accounts for the variability in the response of the eccentric cell to light. The main idea of this theory is that the source of randomness in the impulse rate is "noise" in the generator potential. Another essential aspect of the theory is that the process which transforms the generator potential "noise" into the impulse rate fluctuations may be treated as a linear filter. These ideas lead directly to Fourier analysis of the fluctuations. Experimental verification of theoretical predictions was obtained by calculation of the variance spectrum of the impulse rate. The variance spectrum of the impulse rate is shown to be the filtered variance spectrum of the generator potential.
29 citations
TL;DR: In this article, the nature of the reflected signal is considered for an electromagnetic impulse impinging on a semi-infinite plasma and a finite plasma slab terminated by a perfectly conducting surface at arbitrary angles of incidence and for both polarizations.
Abstract: The nature of the reflected signal is considered for an electromagnetic impulse impinging on a semi-infinite plasma and a finite plasma slab terminated by a perfectly conducting surface at arbitrary angles of incidence and for both polarizations. The inverse Fourier transform technique is used and leads to a statement for the reflected signal in terms of Bessel functions of the first kind. The results are shown graphically for both the TE and TM case for all angles of incidence between normal and π/2.
25 citations
TL;DR: In this article, a more complete analysis of low- ohmic tubular type and squirrel cage type resistors including such effects is presented, and a compensation network of passive electronic components that permits improved measurement of high energy impulse currents.
Abstract: In high-voltage technology, plasma physics and power electronics low-ohmic resistors are frequently employed to measure high, rapidly changing currents. Their voltage drop is adversely affected by stray inductances and skin effect. A more complete analysis of low- ohmic tubular type and squirrel cage type resistors including such effects is presented. This paper also develops a compensation network of passive electronic components that permits improved measurement of high energy impulse currents.
23 citations
01 Jul 1971
TL;DR: In this article, a two-dimensional initially strained elastic body is excited by a point impulse and expressions for the various displacement components in a form which is readily evaluated by residues are given.
Abstract: A two (spatial) dimensional initially strained elastic body is excited by a point impulse. Expressions are found for the various displacement components in a form which is readily evaluated by residues. The solid itself is characterized by three parameters which depend on the material properties and the initial deformation. For the case when two of these parameters are equated, explicit expressions for the displacements are given along the Cartesian axes passing through the origin of the point impulse. Wave front singularities and lacunas are identified and discussed. Some typical numerical results are given.
21 citations
TL;DR: In this article, the minimum impulse transfer between circular orbit and hyperbolic trajectory velocity vector, assuming fixed transfer times, is estimated for a single-orbit trajectory with a fixed transfer time.
Abstract: Minimum impulse transfer between circular orbit and hyperbolic trajectory velocity vector, assuming fixed transfer times
CERN1
TL;DR: In this article, the summed energy spectra obtained in a 600 MeV (p, 2p) experiment on 12C, 28Si and 40Ca have been analyzed so that a large amount of the information from a non-symmetric coplanar experiment is utilized.
TL;DR: In this paper, the breakdown potential gradient of sulphur hexafluoride (SF6) at pressures up to 4 kg/cm2 absolute against power frequency, switching impulse and standard impulse voltages in nearly uniform fields such as plane-plane, sphere- sphere, and coaxial cylinder electrode configurations.
Abstract: This paper describes the breakdown potential gradient of sulphur hexafluoride (SF6) at pressures up to 4 kg/cm2 absolute against power frequency, switching impulse and standard impulse voltages in nearly uniform fields such as plane-plane, sphere- sphere, and coaxial cylinder electrode configurations. Electrode material, smoothness and polarity effect are also investigated for coaxial cylinders.
TL;DR: Inhibition from neighboring eccentric cells has an effect on the variability of firing of a given eccentric cell, and the reduction in the average impulse rate which is caused by inhibition decreases the variance of the impulse rate, but this reduction of the average rate increases the coefficient of variation.
Abstract: Inhibition from neighboring eccentric cells has an effect on the variability of firing of a given eccentric cell. The reduction in the average impulse rate which is caused by inhibition decreases the variance of the impulse rate. However, this reduction of the average rate increases the coefficient of variation of the impulse rate. Inhibitory synaptic noise should add to the low frequency portion of the variance spectrum of the impulse rate. This occurs because of the slow time course of inhibitory synaptic potentials. As a consequence, inhibition decreases the signal-to-noise ratio for low frequency modulated stimuli.
TL;DR: In this paper, an impulse generator circuit of n stages with the overvoltage behaviour of the spark gap is considered. But the circuit is not considered in this paper, as it is not suitable for the measurement of the impulse voltage.
Abstract: The calculation of electromagnetic transients is applied to an impulse generator circuit of n stages with the overvoltage behaviour of the spark-gaps taken into account. Measurements of the impulse voltage by a damped-capacitive divider and of the subsequent firing of the sphere gaps by streak photography with an image converter camera illustrate good agreement between equivalent model and actual circuit.
TL;DR: The model simulates the generator potential of the spindle and the time dependent change of sensitivity at the impulse generating membrane, and it is shown that the impulse patterns of secondary muscle spindle afferents can be simulated quantitatively.
Abstract: A simple model has been employed to describe and interprete measurements from deefferented muscle spindle afferents with static and dynamic stimulation; the model simulates the generator potential of the spindle and the time dependent change of sensitivity at the impulse generating membrane. The properties of the model in transforming the steady and time dependent analogue signals into impulse patterns are demonstrated, and the influence of the various parameters on the response characteristics have been investigated. Results from simulations are compared with experimental data, and it is shown that the impulse patterns of secondary muscle spindle afferents can be simulated quantitatively. The frequency distributions of impulse intervals and different sequential dependencies within the impulse patterns are analysed.
TL;DR: In this article, a two-dimensional Cauchy-Poisson problem is considered where the initial surface disturbance is a given localized constant elevation (or depression) at the water surface with no initial impulse.
Abstract: A two-dimensional Cauchy-Poisson problem is considered where the initial surface disturbance is a given localized constant elevation (or depression) at the water surface with no initial impulse. The solution for the surface profile obtained from the linearized theory of water waves is in the form of an improper integral and asymptotic methods are used to approximate the ‘exact’ solution. The asymptotic solutions are compared to a direct numerical integration of the integral to determine the region of application of asymptotic methods. Experimental data and analytic solutions are compared to determine the region of validity of linearized theory. Nonlinear effects are clearly noted as the height of the elevation (or depression) and length of the disturbance increase.
TL;DR: In this article, an approximation method has been developed which can be carried out to any degree of accuracy by an iterative procedure by using a slide rule to calculate the resistance values necessary to generate a particular double exponential impulse shape.
Abstract: The calculation of the resistance values necessary to generate a particular double exponential impulse shape or the calculation of the two time constants from the resistance and capacitance values is a difficult and time consuming problem if done rigorously. In order to simplify these calculations, an approximation method has been developed which can be carried to any degree of accuracy by an iterative procedure. For normal purposes the initial calculations, done with a slide rule, will yield results of a sufficiently high accuracy.
TL;DR: In this article, the geometrical theory of diffraction has been applied to analysis of the backscattered fields of a cube in the plane normal to four edges of the cube, which are then combined with experimental data and transformed to obtain impulse, step, and ramp responses in the time domain.
Abstract: The geometrical theory of diffraction has been applied to analysis of the backscattered fields of a cube in the plane normal to four edges of the cube. The results of this diffraction analysis are used to calculate the backscattered fields at harmonically related frequencies, which are then combined with experimental data and transformed to obtain impulse, step, and ramp responses in the time domain. The inclusion of the calculated high-frequency data results in a more precise determination of the time-response waveforms than is possible with only low-frequency measured data. As an example of the results, the impulse, step, and ramp responses for vertical and horizontal polarization are presented for θ = 0° (specular direction), 30°.
TL;DR: Inequality constraints in N impulse solutions are introduced in this article, where penalty function and its gradient with respect to control variables are assumed to be linear in the control variables' weights.
Abstract: Inequality constraints in primer optimal N impulse solutions, introducing penalty function and its gradient with respect to control variables
TL;DR: In this article, an approximation to the far-field, backscattering response for an electromagnetic impulse is given for two water sphere sizes. Butler et al. showed that transient effects are confined effectively to an equivalent space period of less than six diameters and can be neglected in all operational applications of pulse radar to rain detection.
Abstract: Approximations to the far-field, backscattering response for an electromagnetic impulse are shown for two water sphere sizes. For small electrical sizes, the scattering is described by an electric dipole; for large electrical sizes, a combination of reflection from the front interface, creeping waves, and surface currents excited as the impulse moves across the sphere is used. It is shown that transient effects are confined effectively to an equivalent space period of less than six diameters and can be neglected in all operational applications of pulse radar to rain detection.
TL;DR: In this paper, the response of two weakly coupled oscillators, one of which is subjected to an initial impulse, is examined by a simple perturbation analysis, and an expression for the time-dependent energy flow is derived.
TL;DR: In this paper, a perturbation of relative humidity is used as a trigger to start the convection in a two-dimensional numerical model of a cumulus cloud, and the effects of varying the width and depth of the perturbations are studied.
Abstract: A perturbation of relative humidity is used as a trigger to start the convection in a two-dimensional numerical model of a cumulus cloud. The effects of varying the width and depth of the perturbation are studied. The rate of growth, eventual cloud height, liquid water content, and updraft strength are strongly dependent on depth of the impulse; but for realistically shallow depths, these values are in reasonable agreement with observations of real clouds. As in the case of one-dimensional models, the ultimate cloud height is dependent on the width of the impulse, but perhaps to a lesser extent.
Patent•
22 Feb 1971TL;DR: In this article, a transmission line system having a primarily signal-initiating section and a mainly signal-radiating section, along all of which transmission line sections traveling electromagnetic waves may propogate without adverse interference caused by impedance discontinuities, is employed cyclically as an energy storage device and as an impulse radiation device having spacially directive characteristics.
Abstract: A transmission line system having a primarily signal-initiating section and primarily signal-radiating section, along all of which transmission line sections traveling electromagnetic waves may propogate without adverse interference caused by impedance discontinuities, is employed cyclically as an energy storage device and as an impulse radiation device having spacially directive characteristics.
TL;DR: In this paper, the induced pseudoscalar form factor F p ( q 2 ; i ↔ f) in weak leptonic nuclear processes was calculated using the impulse approximation and applying the PCAC hypothesis directly to nuclei.
TL;DR: In this article, a binary transversal filter (b.t.f) is discussed in which weighting coefficients are quantized, resulting in designs which are particularly suited to microcircuit implementation and digital programming of impulse responses.
Abstract: A binary transversal filter (b.t.f.) consists of a tapped shift register and a set of weighting resistors which determine its impulse response. B.T.F.s are discussed in which weighting coefficients are quantised, resulting in designs which are particularly suited to microcircuit implementation and digital programming of impulse responses. The precision to which frequency-response specifications may be made is determined as a function of the quantisation error. A number of possible applications are discussed.
TL;DR: In this article, it is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason the interaction between the generator and the measuring circuit is of paramount importance to the voltage across the test object.
Abstract: After some basic considerations the dynamic properties of the measuring system are subjected to a general examination based on a number of responses, characteristic of the system. It is demonstrated that an impulse circuit has an internal impedance different from zero, for which reason the interaction between the generator and the measuring circuit is of paramount importance to the voltage across the test object. Based on the measured values the determination of the applied voltage is considered.