Sine Waveform Research Articles

The resonance effect of a wire in response to transient waves

A resonance effect of transient fields on a thin conducting wire is described. Based on the analysis of the wire's characteristic spectrum, its backscatter, bistatic, and specular scattering are investigated in response to a one-cycle sine waveform. The responding waveforms are discussed in terms of traveling waves. It is found that the resonance effect is directly associated with the excitation of a very strong traveling wave.

Wheel running raises body temperature and changes the daily cycle in golden hamsters

The purpose of this study was to characterize the influence of wheel-running activity on temperature circadian rhythm in golden hamsters. Amplitude of body temperature rhythm was significantly higher in animals that had access to the running wheel. Qualitatively, wheel running resulted in squaring of temperature rhythm waveform, a phenomenon that was independent of ambient illumination. When the hamsters had access to an immobilized wheel, the effect on temperature was no longer observed. Fast Fourier Transformation after subtracting 24-h sine waveforms (to rule out harmonics of the principal frequency), indicated distinct secondary components of the rhythms, i.e., a 12-h component in animals that had access to the wheels and an 8-h component in animals that did not. The rise in body temperature could be dissociated from the start of the activity period, body temperature augmenting before the time of light-dark transition, while activity increased about 12 min later. On the first night after presentation of an estrous female, the temperature cycle in male hamsters that did not access to the wheels was similar to that found in animals running on the wheels; the effect was no longer observed in subsequent nights. The results contribute to the view that the spontaneous locomotor activity in hamsters has a significant effect on temperature cycle.

Temporal asynchrony of less than one-half cycle can be detected in harmonic complexes

In previous experiments on asynchrony detection in multicomponent complexes [Zera and Green, J. Acoust. Soc. Am. 93, 1038–1052, 1571–1579 (1993)], stimuli in which each component began or terminated at a zero crossing of the sine waveform were employed. Thus, the measurable range of asynchrony for a given component was limited to values larger than one-half the component period. In this experiment, the zero-crossing restriction is relaxed and the results show that the listeners’ asynchrony thresholds lie between 0.1 and 0.5 of the signal period for the conditions most favorable to the detection of asynchrony, namely, a harmonic complex with the asynchrony occurring at onset.

ディジタルPLLを用いたしま画像からの実時間形状復元処理 (第2報)

A real-time method is developed for measuring 3-dimensional profiles from fringe patterns generated by moire-topography or a deformed grating method. This paper presents theoretically relationship between object shapes and phases of fringes. It also describes the construction of an experimental system which uses a Digital Phase-Locked Loop (DPLL) circuit. Furthermore, experimental results that confirm the DPLL circuit's performance are reported. In the system, a video-camera scans the fringe patterns across the array of fringe stripes. The video signal has a sine-wave form. The low frequency component of the wave is eliminated by a high-pass filter and its output is digitized by an A/D converter. The phase restoration of the digital signal is performed by the DPLL circuit. The obtained phase signal is proportional to relative distance between the camera and the object. Then the phase signal is converted into analog signal by a D/A converter and the results are displayed as gray-level images on a CRT monitor and also as perspective diagrams on an oscilloscope. An exact profile of the object can be obtained at the video-rate with this method.

Backscatter from periodic surfaces measured to high diffractive order

Underwater backscattering measurements are reported on a variety of polystyrene foam gratings. Targets were of the sine wave, Stokes wave, and isosceles wedge forms. Two periods of about 37.6 and 62.7 mm were investigated. All targets had rms heights (h) of about 2.2 mm. To achieve far-field conditions of general interest, a transducer was used in pulse-echo mode at the focus of an acoustic lens. Techniques to focus, align, and monitor the optical system are described. Backscattered reflectivity was measured for angles of incidence up to 45 deg. Parametric plots of reflection amplitude versus hk are presented for measurable diffraction orders. Comparison is made with Huygens–Fresnel–Kirchhoff physical optics theory with a modification that takes into account the shading at the grating. Agreement is very good. Other authors have used various rule-of-thumb criteria for the applicability of the Kirchhoff approximation. These rules are calculated and compared with the witnessed performance in this experiment. The criteria are seen to be somewhat pessimistic—the Kirchhoff approximation gave better results than indicated by the criteria.

Sawtooth contrast sensitivity: Effects of mean illuminance and low temporal frequencies

Temporal contrast sensitivity was measured for mirror-image sawtooth (rapid-on and rapid-off) and sine waveforms for a 1.8 deg foveal target. In one experiment, contrast sensitivity was measured for 2–26 Hz stimuli at target mean illuminance levels of 5–1260 td. At 5 td, contrast sensitivity functions for sawtooth and sine waveforms, expressed in terms of the Fourier fundamental amplitude, are equivalent. At higher light levels, sawtooth sensitivity increasingly exceeds sine sensitivity and rapid-off (decremental) sawtooths show progressively greater sensitivity than rapid-on (incremental) sawtooths. This pattern of results was obtained for two color-normal observers and for a deuteranopic observer. In a second experiment, sawtooth and sine sensitivity was tested at 500 td with an extended low-frequency range, to 0.5 Hz. Rapid-off and rapid-on sensitivities declined only slightly at low temporal frequencies in contrast with sine sensitivity. To interpret our data, we evaluate two single-pathway models (last-stage asymmetric detector and compressive response-intensity nonlinearity) and a dual-pathway model in which incremental and decremental waveforms are detected by separate ON and OFF visual mechanisms.

A Wide-Pulse-Width Electrical Stimulator For Use On Denervated Muscles

A computer-controlled electrical stimulator, capable of providing pulse widths as wide as 25 milliseconds, is described at a block diagram level of hardware and software. The stimulator provided a maximum peak current of 125 milliamperes at a frequency between 1 and 40 Hz. The stimulator can provide sine, square, rectangular, triangular or sawtooth waveform outputs in either a monophasic or a biphasic mode of operation. This device was tested on four male and two female clinical research subjects with paraplegia. The quadriceps muscle was examined. Based on studies reported here, electrical stimulation was applied at a frequency of 10 Hz and at a pulse width of 25 milliseconds. To exercise the denervated muscles, a pulse train was sustained over a three-second period during which stimulation was linearly increased to a final impulse peak current of 100 milliamps. Six seconds were allowed between contractions. Exercise was continued three times per week, and changes in muscle tone and strength were noted. Results of these experiments showed that in over half of the research subjects examined here, purposeful movement against a load could be achieved with wide-pulse-width electrical stimulation. The implications of the results are discussed.

Failure of countershock-type pulses in vitro to adversely alter mitochondrial oxidative phosphorylation

The aim of the study was to investigate a potential mechanism of myocardial injury after DC countershock. The effect of countershock-type electrical discharges on rabbit heart mitochondrial oxygen consumption was measured in vitro using a novel respiration cell. Mitochondria were isolated from the hearts of adult Dutch and New Zealand White rabbits. Single rectangular shocks (voltage gradients 20 to 80 V/cm; 5 ms duration) caused no significant changes in state 3 oxygen consumption in standard incubation medium. Single and multiple defibrillator shocks (critically damped sine waveform; 5 ms duration) with peak voltage gradients of 242 to 659 V/cm similarly had no significant effect on state 3 oxygen consumption. At voltage gradients similar to and greater than those causing myocardial cell injury and necrosis, electrical discharges do not directly depress mitochondrial function. Therefore, the reduction in mitochondrial oxygen consumption observed following transthoracic shocks in vivo may invoke other mechanisms (eg, intracellular calcium influx, high circulating noradrenaline, or free radical formation in the intact heart).

Influence of Chloride Ions on the Anodic Dissolution of Tin in Bicarbonate and Phosphate Solutions at pH 8

The influence of Cl− ions on passivated tin in 0.3M and 0.5M bicarbonate or phosphate solutions of pH 8 has been studied. The growth of a passive film was carried out in deaerated chloride free solution at to a constant thickness of 4 mC cm−2 and the film breakdown potential was determined potentiodynamically in Cl− containing solutions. The film breakdown potential was found to increase linearly with the potential scan rate. The critical pitting potential (breakdown potential at zero scan rate) decreased linearly with . The bicarbonate and phosphate ions inhibited the chloride attack, the effect being greater for bicarbonates. A rough, bare tin surface in the corrosion zones was observed in the phosphate solutions, whereas the pits were covered by corrosion products in the bicarbonate solutions. The current oscillations observed during experiments on the preoxidized electrode were very regular in the case of and : sine waveform with the same frequency of ∼0.3 Hz. However, the variations became chaotic when the applied potential was more positive than the breakdown potential.

垂直上昇気流中における波板形エリミネータの液滴分離特性

In this paper, the separation performance of corrugated eliminators is investigated experimentally, and the eliminators are all held perpendicular to the vertical upward flow of air laden with water droplets.The plates of eliminators used here are made of polyvinyl chloride, and are approximately represented by the sine-wave form. These eliminators have four different wavelengths of 130, 76, 63, 32 mm, wave amplitudes of 18, 9.0, 8.0, 4.5 mm and gaps between the plates of 30, 15, 15, 12 mm, respectively, and their bending numbers are six.Experiments have been made varing from 0.5 to 3.0 m/s in mean air velocity. In vertical upward air flow, the acceleration of gravity has slightly influence on the separation efficiency and the water-film on the eliminator plate surface has also slightly influence on the pressure loss coefficient, respectively.Obtained separation performances are compared with the results predicted by theoretical analysis which has been presented before.

Chaotic Response of a Slider Crank Mechanism

A physical and corresponding theoretical model of a slider-crank mechanism is presented that approximates the single mode response of a continuous beam under a time periodic excitation in which the spatial distribution of the forcing is in the form of a half sine wave. The purpose of the model is to investigate the existence of chaos in systems having rigid members, as opposed to the highly flexible structures most often seen in chaotic demonstrations. The experimental construct displays complicated dynamical responses, including chaos, while the idealized theoretical model only supports the existence of a period one response. However, it is shown that the addition of an extremely small external perturbation will cause the response to demonstrate what appears to be a robustly chaotic response. A comparison of the Lyapunov exponents between this construct and the experimental model show close agreement.

Radio frequency sheaths—adjustable waveform model

An approximate analytic description of radio frequency (rf) discharge sheaths is given here. This description employs simple power-law equations, obtaining results for a family of sheath voltage waveforms. Both low-pressure (‘‘free space’’) and high-pressure (‘‘collisional’’) regimes are analyzed, yielding power-law dependences of voltages, fields, and charges on distance into the sheath. The resulting sheath model yields asymmetric discharge sheath heights 1.1–1.3 times the corresponding dc sheath model. This family of sheath voltage waveforms is shown to be consistent with experimental sheath voltage waveforms, through experimental measurements of particle arrival times at rf sputtering targets with various electrode area ratios and chamber pressures. The imposition of a nonsinusoidal waveform on the sheath has interesting implications for voltages and ion flows in the remaining regions of the discharge. Ions may be accelerated from the ‘‘presheath’’ region both toward and away from the sheath around a negatively biased target. This is in contrast with dc sheaths, where ions are accelerated only toward the more negative electrode. Thus, ion bombardment of both the target and the counterelectrode is indicated by this model of asymmetric rf discharges. Final sections of this paper consider the velocity of the glow electron wavefront in the sheath, and the close correspondence between these power-law solutions and sine waveforms.

Monocular without stereopsis with and head movement

Random dots moving with various velocity gradients were presented to observers; the motion was yoked to head movement in one condition and to no head movement in another. In Experiment 1, 12 observers were shown motion gradients with sine, triangle, sawtooth, and square waveforms with amplitudes (equivalent disparities) of 12' and 1 degrees 53'. In Experiment 2, 48 observers were shown only the sinewave or square-wave gradient of 1 degrees 53' disparity either with or without head movement so that the observers' expectation to see depth in one condition did not transfer to another. The main findings were: (1) with 12' disparity, the head-movement condition produced perceived depth but almost no perceived motion, whereas the no-head-movement condition produced both perceived depth and perceived motion; (2) with 1 degrees 53' disparity, both conditions produced perceived depth and perceived motion; and (3) when the expectation to see depth was removed, the no-head-movement condition with the square-wave gradient produced no perceived depth, only motion. We suggest that monocular stereopsis with head movement can be achieved without perception of motion but monocular stereopsis without head movement requires perception of motion.

An experimental study and analysis of the behaviour of rock under cyclic loading

In this paper, two types of cyclic loading tests are described. The factors affecting the deformation of rocks are discussed. The endochronic constitutive equations are noted and applied to fit the test data. Conclusions are as follows: (1) During cycling, the total deformation of the specimen consists of initial deformation induced by static loading, creep deformation and damage deformation produced by cycling itself. The damage deformation is the main factor that results in the specimen failing. (2) There is a critical strength that is related to amplitude, loading rate and waveform. This critical strength named cyclical strength is lower than the static strength. (3) The cycle amplitude and the loading waveform have important effects on deformation. In each cycle, the deformation caused by sine waveform loading is larger than that by triangle waveform loading. The larger the cycle amplitude, the shorter the working-life. (4) During cyclic loading, the lateral deformation develops faster than the axial deformation. (5) Because of the existence of damage deformation, the working-life in cyclic loading is less than that in creep. (6) For cycling in the pre-failure and post-failure regions, the specimen shows different deformation behaviour. (7) The endochronic constitutive equation has an ability to describe the stress-strain curve under cyclic loading conditions and fits the experimental data well.(A)

Tensile and tear failure of plasticized poly (vinyl chloride)/epoxidized natural rubber miscible blends

A study on the tensile and tear failure of miscible blends of plasticized poly (vinyl chloride), PVC, and epoxidized natural rubber (ENR) was carried out. Fractographs were taken in a scanning electron microscope in order to obtain an insight into the failure mechanism of the samples. It was found that low ENR blends failed by shearing in tensile testing, and they exhibited irregular stick-slip deformation and characteristics like vulcanizates in tear testing. Blends of plasticized PVC and ENR were more flexible than the individual components. As a result of the geometrical effect the tear fracture surface has rougher features than the tensile fracture surface. Sinusoidal wavy tear patterns in the form of a typical sine wave and rectified half sine wave of the fracture surface are characteristic features of tear resistant non-vulcanizates of rubber-like materials. Moreover, the study revealed that there were no features of phase separation of PVC and ENR due to incompatibility at any of the fracture surfaces examined.

A digital method for sinewave generation

A simple method to digitally produce a sine wave-form with constant amplitude over a relatively wide band of frequencies is described. The method is based on the generation of a number of samples per cycle of the sine wave-form, using an up/down counter and a decoder, and then processing these samples in a summing amplifier and in a controlled-gain amplifier to produce a staircase approximation of the sinewave. The total harmonic distortion of the resulting waveform can be reduced substantially by inserting a low-pass filter.

Cardiac injury with damped sine and trapezoidal defibrillator waveforms

To assess defibrillator-induced cardiac damage, 49 anaesthetized greyhounds received either no shocks (control group) or five shocks from a defibrillator delivering one of five waveforms (Lown, Edmark, Belfast damped sine waveforms: 5 and 20 ms trapezoidal waveforms). At 3 days the hearts of the 36 surviving dogs were examined for macroscopic damage. The Belfast and Edmark waveforms caused significantly more damage (mean 21.1 +/- SEM 2.9 g and 16.0 +/- 3.7 g) respectively than the Lown waveform (3.5 +/- 1.3 g) P less than 0.01. The 20 ms trapezoid caused significantly more damage (8.1 +/- 3.1 g) than the 5 ms pulse (0.7 +/- 1.3 g) P less than 0.05). The ventricular ectopic counts per minute were not significantly different in the three sine wave and 20 ms trapezoidal groups at 24 and 48 h (P greater than 0.05), but at 2 and 72 h were significantly greater in the Belfast and Edmark groups than in the Lown group (2 h, Belfast P less than 0.01, Edmark P less than 0.05: 72 h P less than 0.05). At 15 min there was more right chest ST-segment elevation in the Belfast than in the Lown, Edmark and 20 ms trapezoid groups (P less than 0.01), while left chest ST elevation was greater in the Belfast and Edmark than in the Lown (P less than 0.05) and 20 ms trapezoid groups (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Transthoracic defibrillation threshold of sine and trapezoidal waveforms in defibrillation.

The transthoracic defibrillation threshold of trapezoidal (2.5-, 5-, 10-, 15-, 20-, 40-, and 55-msec duration) and damped sine waveforms were established in groups of anesthetized greyhounds. Of the seven trapezoidal waveforms, the threshold current was lowest for the 20-msec pulse but was not significantly different for the 5-20-msec pulses (p greater than 0.05). The threshold delivered energy was not significantly different for the 2.5-20-msec waveforms. The 40- and 55-msec pulses had significantly greater delivered energies than the shorter pulses (p less than 0.01). The transthoracic defibrillation threshold of two trapezoidal (5- and 20-msec) and three damped sine waves (Lown, Edmark, and Belfast) showed that the threshold transthoracic current and energy were not significantly different for the 5-msec trapezoid and three sine waves (p greater than 0.05). The threshold transthoracic energy for the 20-msec trapezoid was significantly greater than that of the four other waveforms. The threshold current for the 20-msec trapezoid was significantly less than that of the Belfast and Edmark waveforms only. Thus, none of the three damped sine waveforms was superior, with the 5-msec trapezoid producing similar results. Although the 20-msec trapezoid had the lowest threshold current, it had the highest delivery energy.

Characterisation of a phase-sensitive detector

The phase-sensitive detector (PSD) operating particularly as a synchronous rectifier has an important role in many benchtop instruments, typical of which is the modern LCR component meter. The performance of the PSD determines the accuracy and frequency range of the overall instrument. Its characterisation by direct methods is particularly difficult to achieve by virtue of the necessity for an accurate knowledge of the relative phase between sine and switching waveforms at the PSD.The paper offers an alternative approach to characterisation of the PSD that circumvents the need for direct phase measurements. It calls for the use of a purpose designed sine-square generator which is relatively easy to achieve with today's technology. PSDs in the form of a buffered voltage-switching circuit and a track/hold circuit are examined in some detail. A statistical analysis is provided for the error bounds expected in the phase estimates.The work described can be readily adapted to improvements in phase measurement in existing LCR component meters. A technique called adaptive reference phase (ARP) is introduced for this purpose. This has particular relevance to capacitor measurements where accurate estimates of loss angle are at a premium.

アルミニウムのアルカリ性浴陽極酸化皮膜に及ぼす電流波形および周波数の影響

Specimens were electrolyzed by AC with various current waveform (sine wave, square wave and saw-tooth wave) and frequencies (10∼kHz) in NH4OH-NH4F system bath and NaOH-H2O2 system bath at a current density of 2A/dm2 for 30min, at 20°C.The use of a 10Hz square waveform resulted in a formation of a thicker film (5∼6μm) in both the NH4OH-NH4F and NaOH-H2O2 system baths. In the former case (NH4OH-NH4F system bath), film thickness decreased at frequencies above about 200Hz, reaching about 1∼2μm at frequencies above 1kHz. In the latter case (NaOH-H2O2 system bath), film thickness decreased according to increase of frequency, and it was about 0.5∼1μm in thickness at high frequency more than about 500Hz.The films anodized in the NaOH-H2O2 system bath with square current waveform was much rougher than those fromed using with sine or saw-tooth waveforms and larger pores were observed by microscope.Many large pores were observed in the coatings formed at high frequency and those formed in NaOH-H2O2 system bath had larger pores than those fromed in NH4OH-NH4F system bath.