Sinusoidal Impulse Research Articles

Nonstationary Vibrations of an Electroelastic Spherical Shell in an Acoustic Layer

An analytical and numerical approach to the study of processes in a hydroelectroelastic spherical shell–acoustic layer system is proposed. The perturbed motion of the fluid and the shell is modeled by the relations of the acoustic approximation and theory of thin electroelastic shells. Using the method of image sources, the method of separation of variables, and the Laplace integral transform in the time coordinate, the problem is reduced to an infinite system of Volterra integral equations with arguments with a delay. The system is solved numerically using the method of reduction. The numerical results are given for the case of the perturbation of the shell as a point source by an electrical load in the form of a sinusoidal impulse.

Pulse Shape Effects in Electrocaloric Cooling.

We report on the solution of the heat equation, which describes the electrocaloric effect in a ferroelectric layer. The dependence of the heat flux at the layer interface and the thermodynamic efficiency on the shape and frequency of the applied pulse is investigated. According to the calculations, the dependence of the efficiency on the frequency for a rectangular and sinusoidal pulse has a markedly different character. The maximum efficiency at 0.74 is achieved by a sinusoidal impulse at a frequency of 77.6 mHz. The new approach allows for better optimization of the cooling system. To model a heat switch, it is proposed to use a change in the Biot number over time. Theoretical calculations are compared with experimental results for a 0.5-mm-thick barium titanate plate. The maximum heat flux that can be created for a given plate under an electric field of 2 MV/m with an ideal heat switch turned out to be equal 120.72 W/m2.

Influences of impulse excitation and vibration on thermoelastohydrodynamic characteristics of spur gear drive

AbstractIn this paper, an elastohydrodynamic impact model is proposed, and the prediction of lubricating film performance considering squeeze effect and thermal effect is presented. Effects of sinusoidal impulse load, sinusoidal impulse entrainment velocity, multi‐frequency vibration, and acoustic noise on thermo‐mechanical characteristics of gear lube are numerically investigated. Results show that both sinusoidal impulse load and sinusoidal impulse entrainment velocity can cause remarkable increases in central film thickness and minimum film thickness and induce small reduction in friction coefficient. The sinusoidal impulse load causes considerable increase in central film pressure; however, the sinusoidal impulse entrainment velocity induces significant decrease in central film pressure. The multiple high constant frequency vibration causes considerable increment in film pressure, but maintains small fluctuation in film thickness. Additionally, the consequence of multiple high constant frequency vibration induces evident reduction in friction coefficient.

Dynamic Collapse Mechanism of Global Hull Girder of Container Ships Subjected to Hogging Moment

The purpose of the present study is to investigate dynamic ultimate strength of global hull girder of container ships using large-scale nonlinear finite element analysis (FEA). A series of time domain nonlinear finite element (FE)-simulation is carried out using large-scale FE models of a 8000 twenty-foot equivalent unit (TEU) container ship where a hogging moment is applied to the midship section. Five types of finite element models (three full models, a half hold model, a one transverse model) are used. These models adopt elastoplastic material model, which includes strain rate effect. The hogging moment, which is modeled by sinusoidal impulse, is applied to these models, and collapse mechanism as well as dynamic hull girder ultimate strength is investigated by varying the load time duration. Moreover, effects of load time duration, mass inertia, strain rate, and analysis models are investigated in detail. It is found from the present study that ultimate strength as well as collapse mode is significantly dependent on load time duration of hogging moment.

Cosmology, Mass and the Super Force

Linking cosmology and particle physics has long been an outstanding problem. The problem was with the errand theory of Einstein’s Relativity. Here we provide these two field with one equation using Matrix Structural Analysis techniques. The theory of Astro-Theology melds almost perfectly with well established particle physics including the neutron, proton and the electron. Proof for these equations that we make use of here is described in JS Przemeiniecki seminal work. Mass dampens out the superforce which is a sinusoidal impulse force.

Effect of unsteady natural convection mass transfer caused by g-jitter on protein crystal growth under microgravity

ABSTRACTDetailed numerical analysis is presented for the effect of unsteady natural convection caused by g-jitter on protein crystal growth (PCG) under microgravity. The results show that for step impulse disturbances with the strength of 10−2 g0, the convection can decrease the crystal growth rate, especially for the higher-frequency g-jitter. For sinusoidal impulse disturbance with different amplitudes g*, the effect of convection on PCG is good for g* = 10−4 g0 and it is bad for g* = 10−3 g0. In comparison with the case of crystal at the bottom, the effects of unsteady convection caused by g-jitter for crystal suspended are more obvious due to the larger values of r. However, the crystal suspended in the container can more easily remain regular shaped.

Fractional derivatives and periodic functions

This paper studies the periodic functions in the perspective of fractional calculus application. It is shown that the fractional derivative of a periodic signal is periodic if it is defined on the whole real line. Several common fractional derivative formulations are considered, namely the Grunwald–Letnikov, Liouville and Caputo on $$\mathbb {R}$$ , and the two-sided fractional derivatives. It is verified that the fractional derivative of a causal periodic signal is never causal periodic. The periodic behaviour of the fractional linear systems is also studied. If such systems are defined with suitable derivatives the output corresponding to periodic input is also periodic. Is is concluded that only the integer order linear systems can have a sinusoidal impulse response.

Wave propagation in a concrete filled steel tubular column due to transient impact load

This study aims to present a three dimensional finite element model to investigate the wave propagation in a concrete filled steel tubular column (CFSC) due to transient impact load. Both the concrete and steel are regarded as linear elastic material. The impact load is simulated by a semi sinusoidal impulse. Besides the CFSC models, a concrete column (CC) model is established for comparing under the same loading condition. The propagation characteristics of the transient waves in CFSC are analyzed in detail. The results show that at the intial stage of the wave propagation, the velocity waves in CFSC are almost the same as those in CC before they arrive at the steel tube. When the waves reach the column side, the velocity responses of CFSC are different from those of CC and the difference is more and more obvious as the waves travel down along the column shaft. The travel distance of the wave front in CFSC is farther than that in CC at the same time. For different wave speeds in steel and concrete material, the wave front in CFSC presents an arch shape, the apex of which locates at the center of the column. Differently, the wave front in CC presents a plane surface. Three dimensional effects on top of CFSC are obvious, therefore, the peak value and arrival time of incident wave crests have great difference at different locations in the radial direction. High-frequency waves on the waveforms are observed. The time difference between incident and reflected wave peaks decreases significantly with r/R when r/R < 0.6, however, it almost keeps constant when <TEX>$r/R{\geq}0.6$</TEX>. The time duration between incident and reflected waves calculated by 3D FEM is approximately equal to that calculated by 1D wave theory when r/R is about 2/3.

The Specific Features of Red Blood Cell Membranes in Premature Neonates Due to Multiple Pregnancy

Objective: to substantiate the efficacy of bipolar impulses of different shapes and duration. Method. The investigation used the dynamic model II of the mammalian ventricular cardiomyocyte membrane in the guinea-pig, proposed by Luo and Rudy (1994—2000). The cardiomyocyte membrane was acted by substituting the current density of the impulse under study. The threshold impulse energy ratio considered as an integral index of the threshold action (a measure of efficiency) of an impulse measured in μA 2 ms/cm 4 was then calculated. A comparison was made between a classical quasi<sinusoidal impulse, a stepwise quasi-sinusoidal, rectilinear, classical trapezoidal, trapezoidally modulated (the presence of high-frequency, high-amplitude oscillations of current) impulse and its unmodulated equivalent, and a trapezoidal low<angle front tail impulse of the duration equal to that of the classical quasi-sinusoidal one. The shape of the impulses corresponded to the 100-ohm resistance of the chest. Results. The most effective impulses proved to be a quasi-sinusoidal stepwise impulse (229.6 μA 2 ms/cm 4 ), next a classical quasi-sinusoidal impulse (249 μA 2 ms/cm 4 , +9%) and a trapezoidal low<angle front tail one (253.0 μA 2 ms/cm 4 , +10%). The trapezoidally modulated impulse (397 μA 2 ms/cm 4 , +73%) turned out to be lowest effective (in the threshold impulse energy ratio). The other impulses were intermediate between the above impulses in the following order: a modulated trapezoidal impulse equivalent (272.0 μA 2 ms/cm 4 ), next a rectilinear impulse (273.5 μA 2 ms/cm 4 ), and a classical trapezoidal one (307.0 μA 2 ms/cm 4 ). Conclusion. In terms of the excitation threshold of the Luo-Rudy model of the guinea-pig cardiomyocyte membrane, the most effective impulses are quasi<sinusoidal stepwise, next quasi<sinusoidal and trapezoidal low-angle front tail ones.

Widely tunable single-bandpass microwave photonic filter employing a non-sliced broadband optical source

We demonstrate a novel microwave photonic filter based on a non-coherent broadband optical source and the variable optical carrier time shift (VOCTS) method. Optical slicing which is essential conventionally is not employed in our scheme. Nevertheless, equivalent "electrical slicing" is performed by VOCTS, generating a passband free from the carrier-suppression effect. The baseband response is eliminated by using carrier-suppression or phase modulation. Single bandpass is also achieved due to the continuous-time sinusoidal impulse response. Detailed theoretical analyses are presented and agree with the experiments quite well.

Einfluss von Interferenz- und Hochvolttherapie auf postoperative Schmerzen und Ödementwicklung nach Implantation einer Knie-Totalendoprothese

PURPOSE: What influence does transcutaneous electrical nerve stimulation have on postoperative pain and oedema after knee arthroplasty? MATERIALS AND METHODS: 60 patients were randomly assigned to one of three groups after total knee arthroplasty: 20 patients received electrical stimulation equipment, 20 patients placebo equipment or stayed without equipment. Postoperatively patients with functional and placebo equipment were advised to use electrical stimulation therapy two to three times a day for 45 min each. The first 30 min were used for control of oedema by high voltage pulsed current with negative polarity and an impulse frequency of 100 pps. The following 15 min were used for pain control with sinusoidal impulse and a frequency of 1 000 Hz. All patients kept a pain diary. Patients were clinically examined and data was collected before, two to three days after and finally a week after the surgery. RESULTS: Pain was lowest in the group with electrical stimulation and reached significancy (p=0.02) on day seven after surgery. Working equipment showed a significant (p=0.012) reduction of circumference of 0.925 cm at knee joint during therapy. At the end of the study, patients with functional electrical stimulation (29°; p=0.027) and placebo treatment (30°; p=0.007) significantly increased the range of motion. The group with stimulation showed the highest HSS score compared to the group without equipment (p=0.003) and the placebo group (p=0.04). CONCLUSION: Transcutaneous electrical nerve stimulation significantly reduced oedema and pain and improved the range of motion and the HSS score.

Boundary-integral modeling of cochlear hydrodynamics

A two-dimensional model that captures the essential features of the vibration of the basilar membrane of the cochlea is proposed. The flow due to the vibration of the stapes footplate and round window is modeled by a point source and a point sink, and the cochlear pressure is computed simultaneously with the oscillations of the basilar membrane. The mathematical formulation relies on the boundary-integral representation of the potential flow established far from the basilar membrane and cochlea side walls, neglecting the thin Stokes boundary layer lining these surfaces. The boundary-integral approach furnishes integral equations for the membrane vibration amplitude and pressure distribution on the upper or lower side of the membrane. Several approaches are discussed, and numerical solutions in the frequency domain are presented for a rectangular cochlea model using different membrane response functions. The numerical results reproduce and extend the theoretical predictions of previous authors and delineate the effect of physical and geometrical parameters. It is found that the membrane vibration depends weakly on the position of the membrane between the upper and lower wall of the cochlear channel and on the precise location of the oval and round windows. Solutions of the initial-value problem with a single-period sinusoidal impulse reveal the formation of a traveling wave packet that eventually disappears at the helicotrema.

On the effect of anisotropy in nonlinear composite materials for stress grading applications-a numerical study

The production technology of carbon-black loaded polyolefins adopted for stress grading purposes in ac cable terminations may impart, in addition to the nonlinear electrical properties, an anisotropic behavior to the material. In this paper a numerical study is presented in order to study the influence of both anisotropy and nonlinearity on the electrical field dynamics inside cable terminations adopting stress grading carbon-black loaded composites. The nonlinear anisotropic conductivity is properly taken into account in the model, allowing a sound understanding of the influence of such property on the stress grading performances of the considered accessory. The numerical results for sinusoidal power frequency and standard impulse voltages demonstrate the role of the different conduction mechanisms on stress grading efficiency and give useful indications for an effective material characterization.

Two-point discrimination of vibratory perception on the sole of the human foot.

The capability for discrimination of vibratory stimuli of the sole of the foot was tested on 12 subjects (6 men, 6 women). Two vibratory stimuli (sinusoidal impulse: frequency, 200 Hz; amplitude, 0.1 mm; duration, 2 sec) were applied at different sites to the sole of the foot. Subjects were asked whether they detected one or two vibratory sensations. The discrimination threshold was defined as the shortest distance at which two vibrations can be differentiated at repeated trials. In addition, the absolute threshold was measured by one plunger (sinusoidal vibration: frequency, 200 Hz; variable amplitude). The values of the absolute threshold (average value, 1.2 microns) were in accordance with the results of other authors. A decrease of discrimination capability was observed along the longitudinal axis of the foot from distal to proximal parts and was about 15 mm at the big toe and 34 mm at the heel. Discrimination at the medial longitudinal arch was inferior to that at the lateral longitudinal arch. This was also true for inverse vibration in which all subjects showed lower thresholds. No relationship was found with respect to thickness of the skin (measured by ultrasound), side of foot, or gender. Determining factors for vibratory threshold might be the density of the Pacinian corpuscles per cm2 as well as their peripheral and central representation. Anatomical or physical factors (e.g., thickness of the skin, impedance of the deeper tissue) can probably be disregarded.

Diffraction of a sinusoidal impulse by a rigid strip

The diffraction of a sinusoidal impulse by an absolutely rigid strip is considered. Approximate formulas are obtained for the field measured at large distances from the strip in the direction of the incident impulse (the case of location). The results are expressed in terms of Fresnel integrals. The possibility of determining the width of the strip and the angle between it and the direction of the incident impulse or the basis of the envelope of the location field is discussed. Graphs of the envelopes for certain specific cases are presented.