Ratio Of Wave Amplitude Research Articles

S-wave attenuation in the Sea of Marmara, Turkey

This paper presents the estimates of frequency-dependent attenuation of S-waves for five different regions of the crust in the Sea of Marmara. The estimation method for the S-wave attenuation is based on the rate of decay of the S-wave to coda wave amplitude ratio with distance, Q s −1. The epicentral distances of the selected earthquakes are between 15 and 70 km and the duration magnitudes are between 2.4 and 3.9. The quality factors, Q s, are calculated at frequencies 1.5, 3, 6 and 12 Hz and a lapse time 50 s. The frequency dependency of average Q s values calculated at these frequencies for five regions is 40±5 f 1.03±0.06. The estimated Q s values for five regions ranging from 13±1 f 1.22±0.05 to 94±3 f 0.83±0.04 indicate the regional differences in the rheology and tectonic activity of the crust.

Effects of an endoscope and fluid with variable viscosity on peristaltic motion

The influence of an inserted endoscope and fluid with variable viscosity on the peristaltic motion has been investigated under zero Reynolds number. The problem is formulated using a perturbation expansion in terms of a variant wave number. The effects of curvature, viscosity, radius of an endoscope and amplitude of the wave on the pressure rise and friction forces on the inner and outer tubes are analyzed. Peristaltic and augmented pumping are discussed. The results show that, the pressure rise increases with increasing wave number, amplitude ratio and radius ratio. Also, it decreases with increasing viscosity parameter. Further, it is independent of wave number, amplitude ratio, radius ratio and viscosity parameter at certain values of flow rate. A comparison with previous studies is given.

Characteristics of Small-Scale Heterogeneities in the Hidaka, Japan, Region Estimated by Coda Envelope Level

We estimated the spatial distribution of small-scale heterogeneities as anomalous amplification of coda level in the Hidaka, Japan, region. We analyzed 2768 seismograms in a frequency range of 1-32 Hz for 24 earthquakes recorded at 62 stations. First, we estimated the site effect of each station, using the coda nor- malization method with regional earthquake data of large epicentral distances. All the data processing was done after the correction of this site effect. Next, we deter- mined coda amplitude factor (CAF), that is, the amplitude ratio of coda waves on each source-station pair relative to the averaged coda amplitude over stations, for earthquakes inside the region. We found systematic spatial variations of CAF, im- plying the existence of localized heterogeneities. At frequencies lower than 2 Hz, the CAF is relatively large in the west of the Hidaka Mountains, implying the possibility of strong heterogeneities with a scale of 0.6-1.3 km there. In a high-frequency range (� 16 Hz), CAF values are large on paths crossing the Hidaka Mountains. From the corresponding lapse time of coda (65 sec), there may be a zone of concentrated heterogeneities beneath the Hidaka Mountains at the depth of 100-120 km.

Normalized input–output minimization analysis of wave propagation in buildings

In previous studies on the earthquake response of buildings, vibration approaches were used more often than wave propagation approaches; thus, wave propagation through a building has not been sufficiently investigated. This paper presents a wave propagation modeling analysis of strong motion records for actual buildings in comparison with an analysis of those in elastic soil media and in analytical building models. We use the normalized input–output minimization (NIOM) method, which can model wave propagation in multiple linear systems by considering the statistical correlation among the strong motions at different observation locations. Output wave models simplified by the NIOM method show two clear peaks that correspond to incident and reflected waves propagating through the building in the vertical direction. Obtained wave propagation properties, such as wave travel time and wave amplitude ratio, at each story of the building are found to reflect the structural properties like rigidity and damping at that story. Thus, the NIOM method is shown to be an effective new method of investigating structural behavior of buildings during earthquakes.

Paradoxical diminution in finger blood flow with exercise predicts adverse outcomes among patients with coronary artery disease

Background: Whereas normal subjects increase finger blood flow during exercise (EX), patients (pts) wth coronary disease (CAD) have been shown to manifest a paradoxical decrease in fmger blood flow with EX. The clinical significance of this obsewatlon is unknown. Methods: 327 CAD pts (mean age 56 * 10,64% male) underwent EX myocardial perfusion SPECT while measuring finger blood flow using peripheral arterial tonometry. Pulse wave amplitude (PWA) ratio was assessed for each EX minute and PWA slope values were determined; slope values ~0 = vasoconstriction. SPECT scans were read blindly using a conventional 20.segment, B-point scale. A follow up of 1.86 + 1 .O years was obtaine for cardiac death, non-fatal myocardlal infarction and revascularization z-60 days after EX testing. Results: There were a total of 34 events (annualized event rate of 5,7%/year). A negative (versus positwe) slope for PWA during EX was associated with a greater frequency of cardiac events (hazards ratio 3.3 (1.2 9.5), pcO.OOl)](figure). Negative PWA slope was the most potent predictor of events by multivariate analysis, and remained so even after significant clinkxl variables including EX and SPECT results, were forced first into the analysis (adjusted risk ratlo = 2.62 [1.07,6.42]). Conclusions: Paradoxical decrease in finger blood flow during EX is associated with an increased frequency of cardiac events. Moreover, this measure adds incremental value to existing clinical and exercise SPECT data for cardiac risk assessment

Auditory brainstem response in children with iron deficiency anemia.

To investigate the neurosensorial influences with auditory brainstem response (ABR) in iron deficiency anemia. We recorded ABR in 33 children with iron deficiency anemia followed and in 31 healthy children (control group 1, 0-12 months, control group 2, 13-36 months, control group 3, 37-60 months) as a control group. The patients and controls were divided into three group: group I, at 12 months of age, group II, 13-36 months, and group III, 37-60 months. In all groups, composed latency time, inter-peak latency, amplitude of peaks, I-V wave amplitude ratio and waveform were evaluated and compared with control groups. In group I, I-V interpeak latency was increased compared with control group I (4.58 vs. 4.20 ms, p < 0.05). In group II, Wave V latency time and III-V interpeak latency were increased compared with control group 2 (6.21 ms vs. 5.63 ms. p < 0.005 and 0, 48 vs. 0.22 p < 0.005, respectively). In group III, wave I latency time was increased compared with control group 3 (1.56 ms vs. 1.46 ms) (p < 0.05). We considered that increases in ABR latencies might be explained by delayed maturation of myelinisation, which requires iron, and/or by dysfunction of iron containing enzymes.

Motor responses evoked by transcranial magnetic stimulation and peripheral nerve stimulation in the ulnar innervation in amyotrophic lateral sclerosis: the effect of upper and lower motor neuron lesion

We studied the upper (UMN) and lower motor neuron (LMN) innervations of 159 hands from 81 patients with amyotrophic lateral sclerosis (ALS). Eleven patients with various chronic LMN disorders causing weakness in the abductor digiti minimi (ADM) muscle served as LMN controls. Thirty healthy subjects served as normal controls. Cortical motor threshold, central conduction time (CMCT), and motor-evoked response amplitude (MEP) after transcranial magnetic stimulation (TMS) were studied, and the MEP/M wave ratio was calculated. The data was analyzed in the ALS subjects in groups defined by ADM muscle strength and by the presence or absence of clinical signs of UMN involvement. CMCT was not increased in the ALS or LMN disease groups. The threshold was higher in limbs with both weak ADM muscles and UMN signs. The MEP/M wave amplitude ratio was increased in weak muscles in the ALS patients, notably in limbs with no UMN signs, and also in weak muscles in patients with other chronic LMN disorders. It was frequently decreased in strong muscles. There was no difference between bulbar-onset and limb-onset ALS groups, and there was no correlation between threshold and disease duration. We suggest that expressing the data as an index and utilising the MEP/M wave amplitude ratio as a variable is a sensitive method for detecting UMN abnormality in ALS in particular in early affected muscles.

A theory of the fundamental plasma emission of type-III solar radio bursts

Results from plasma wave experiments in spacecraft give support to nonlinear interactions involving Langmuir waves, electromagnetic waves and ion-acoustic waves in association with type III solar radio bursts. In this paper we present a theory of the fundamental plasma emission of type-III solar radio bursts. Starting from the generalized Zakharov equations, considering the pump wave as a pair of oppositely propagating Langmuir waves with different amplitudes, and the excitation of electromagnetic and induced Langmuir waves, we obtain a general dispersion relation for the coupled waves. We numerically solve the general dispersion relation using the pump wave amplitude and plasma parameters as observed in the interplanetary medium. We compare our results with previous models. We find that the stability properties depend on the pump wave numbers and on the ratio of wave amplitude between the forward and backward pump wave. The inclusion of a second pump wave allows the simultaneous generation of up and down converted electromagnetic waves. The presence of a second pump with different amplitude from the first one brings a region of convective instability not present when amplitudes are the same.

Torsion/Simple Shear of Single Crystal Copper

We analyze simple shear and torsion of single crystal copper by employing experiments, molecular dynamics simulations, and finite element simulations in order to focus on the kinematic responses and the apparent yield strengths at different length scales of the specimens. In order to compare torsion with simple shear, the specimens were designed to be of similar size. To accomplish this, the ratio of the cylinder circumference to the axial gage length in torsion equaled the ratio of the length to height of the simple shear specimens (0.43). With the [110] crystallographic direction parallel to the rotational axis of the specimen, we observed a deformation wave of material that oscillated around the specimen in torsion and through the length of the specimen in simple shear. In torsion, the ratio of the wave amplitude divided by cylinder circumference ranged from 0.02–0.07 for the three different methods of analysis: experiments, molecular dynamics simulations, and finite element simulations. In simple shear, the ratio of the deformation wave amplitude divided by the specimen length and the corresponding values predicted by the molecular dynamics and finite element simulations (simple shear experiments were not performed) ranged from 0.23–0.26. Although each different analysis method gave similar results for each type boundary condition, the simple shear case gave approximately five times more amplitude than torsion. We attributed this observation to the plastic spin behaving differently as the simple shear case constrained the dislocation activity to planar double slip, but the torsion specimen experienced quadruple slip. The finite element simulations showed a clear relation with the plastic spin and the oscillation of the material wave. As for the yield stress in simple shear, a size scale dependence was found regarding two different size atomistic simulations for copper (332 atoms and 23628 atoms). We extrapolated the atomistic yield stresses to the order of a centimeter, and these comparisons were close to experimental data in the literature and the present study.

Transport induced by a surface acoustic wave along a slab

The transport of non-equilibrium gases in the flow regime of slightly rarefied gas dynamics within a plane channel bounded by two parallel slabs is addressed. Hydrodynamic derivation of the entrainment of rarefied gases induced by a surface acoustic wave (SAW) along the walls in a confined parallel-plane microchannel is conducted by considering the nonlinear coupling between the interface and the velocity-slip. Both no-slip and slip flow results are obtained with the former ones matched with the previous approach. The critical reflux values associated with the product of the second order pressure-gradient and the Reynolds number decrease as the Knudsen number increases from zero to 0.1. We found when the Reynolds number is larger the surface wave-modulation effect (due to the wave number) to the flow field is significant which represents the strong coupling between the boundary and the flow-inertia term. Meanwhile, the (perturbed) mean flow induced by SAW along the walls of a 2D microchannel is proportional to the square of the wave-amplitude ratio which has been qualitatively confirmed by previous approaches.

UHF法で測定された電磁波第一波の振幅比に基づくGIS絶縁異常の診断

UHF法で測定された電磁波第一波の振幅比に基づくGIS絶縁異常の診断

Vibration measurement method and apparatus

The present invention provides a vibration measurement method and apparatus utilizing a self-mixing type laser Doppler vibrator meter. The vibration measurement method includes steps of: oscillating a laser beam of a predetermined wavelength and applying the laser beam to an object to be measured; mixing the reflected laser beam from the object and the oscillated laser beam for outputting a beat wave; calculating ratio of a beat wave amplitude for the turning point of the vibrating object, with respect to a predetermined reference amplitude; and calculating a displacement amount for the turning point of the vibrating object, according to the calculated ratio. This enables to detect the vibration of the object to be measured, with a high accuracy.

Peristaltic Transport within a Micro-tube

Continuum-mechanic derivations of the entrainment of molecular gases induced by a surface wave (SW) along the wall in a confined micro-tube are conducted by the perturbation method. Both no-slip and slip flow results are presented with the former ones matched with the previous approach. The critical (reflux) pressure-gradient values decrease as the Knudsen number increases from zero. Meanwhile, the (perturbed) mean flow induced by SW along the wall of a micro-tube is proportional to the square of the wave-amplitude ratio which has been confirmed by previous experiments. Stronger nonlinear coupling due to the boundary effect and the streaming flow are observed as the Reynolds number increase to 100 and the wave number of the surface wave is larger.

The influence of hemodynamic stress factors on intracranial aneurysm formation.

Applanation tonometry is a noninvasive method of assessing both peripheral and central arterial blood pressure (BP) profiles. In this study the authors examine whether there are differences in these profiles in patients with intracranial aneurysms when compared with age-matched controls. Carotid artery (CA) and derived aortic BP waveforms were obtained using a pulse wave analysis system. The ratio of the pressure wave amplitude above the systolic shoulder to the total systolic BP (augmentation index [AI]) was recorded. One hundred seventy-three patients with intracranial aneurysms (23 unruptured lesions) and 173 healthy control volunteers were examined. For the patients with aneurysms the right and left CA AIs (mean +/- standard deviation) were 125.6 +/- 23.1% and 128.3 +/- 22.1%, respectively. Corresponding values for the control group were 118.4 +/- 22.6% and 119.4 +/- 21.8%. The calculated AI for the ascending aorta was 29.8 +/- 10.5% and 25.6 +/- 12.2% for patients with aneurysms and control volunteers, respectively. Significant asymmetry in CA AI was seen in patients with aneurysms, the left being greater (p = 0.002). No significant differences were seen in mean BP (108 +/- 14 mm Hg in patients with aneurysms compared with 106 +/- 16 mm Hg in controls; p = 0.2). Multivariate analysis excluded the influence of BP and other potential confounding vascular risk factors for increased AI. Significant differences in AI, both in magnitude and symmetry, were identified in patients with intracranial aneurysms when compared with matched controls.

Numerical Study of a Magneto-fluid Motion Through a Porous Medium Between Two Wavy Plates with Constant Suction

In this note, the problem of an incompressible viscous fluid moving through a porous medium (Brinkman model) between two wavy plates under the effects of a constant inclined magnetic field that makes an angle with the vertical axis and constant suction, are studied numerically by a method related to the method of Takabatake and Ayukawa in 1982. The present approach is not restricted by any of the parameters appearing in the problem such as Reynolds number, magnetic parameter, suction parameter, the wave number and amplitude ratio. The variations in velocity, flow rate and pressure gradient with the above governing parameters are presented. Moreover, the effect of varying the porous medium and the inclined angle is also studied.

Estimating the permeability of the Nojima Fault Zone by a hydrophone vertical seismic profiling experiment

Abstract A multi‐offset hydrophone vertical seismic profiling (VSP) experiment was done in a 747 m deep borehole at Nojima Hirabayashi, Hyogo prefecture, Japan. The borehole was drilled to penetrate the Nojima Fault, which was active in the 1995 Hyogo‐ken Nanbu earthquake. The purpose of the hydrophone VSP is to detect subsurface permeable fractures and permeable zones and, in the present case, to estimate the permeability of the Nojima Fault. The analysis was based on a model by which tube waves are generated when incident P‐waves compress the permeable fractures (or permeable zones) intersecting the borehole and a fluid in the fracture is injected into the borehole. Permeable fractures (or permeable zones) are detected at the depths of tube wave generation, and fracture permeability is calculated from the amplitude ratio of tube wave to incident P‐wave. Several generations of tube waves were detected from the VSP sections. Distinct tube waves were generated at depths of the fault zone that are characterized by altered and deformed granodiorite with a fault gouge, suggesting that permeable fractures and permeable zones exist in the fault zone. Tube wave analysis shows that the permeability of the fault gouge from 624 m to 625 m is estimated to be approximately 2 × 10−12 m2.

Measurements of the trapped particle sideband instability compared to the macroparticle model

The upper and lower sidebands are measured on a traveling wave tube where a cold electron beam is trapped by a large amplitude wave. The two strongly coupled sidebands form a normal mode that is characterized by the sideband growth rates, wave number shifts, amplitude ratio, and phase relationship. The measured values agree only qualitatively with the macroparticle model of Kruer, Dawson, and Sudan [Phys. Rev. Lett. 23, 838 (1969)]. Also, the macroparticle model prediction for a nonlinear product wave does not agree with the experiment. Quantitative agreement is found between the experiment and computer simulations that follow the electron orbits, suggesting that the trapped particle model is too simple for quantitative predictions.

Excitatory and inhibitory corticospinal responses to transcranial magnetic stimulation in patients with minor to moderate head injury

OBJECTIVESThe changes in excitatory and inhibitory responses to transcranial magnetic stimulation (TMS), as attested by motor evoked potential (MEP) and silent period (SP) parameters, were compared in patients who sustained...

Clinical and physiological significance of abnormally prolonged central motor conduction time in HAM/TSP

We measured the central motor conduction time (CMCT), central sensory conduction time (CSCT), F wave and mean F wave/M wave amplitude ratio in patients with HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) and controls. CMCTs in upper (U) and lower (L) limbs were significantly prolonged in HAM/TSP. L-CSCT was significantly prolonged in HAM/TSP, but U-CSCT in HAM/TSP and controls were not significantly different. CMCT and CSCT were significantly correlated in HAM/TSP. U-CMCT, but not L-CMCT, correlated with the clinical severity of HAM/TSP. Although F wave conduction velocity and its occurrence were normal in HAM/TSP, U- and L-mean F wave/M wave amplitude ratio tended to be higher in HAM/TSP, and the L-mean F wave/M wave amplitude ratio was significantly correlated with the L- and thoracic CMCT. These findings demonstrate that the prolongation of CMCT sensitively reflects the extension of the lesions and the disinhibition to the anterior horn cells in HAM/TSP.

New evidence for a low-velocity layer on the subducting Philippine Sea plate in southwest Japan

A distinct precursory phase is sometimes found prior to S arrival, when deep-focus and intermediate-depth earthquakes are observed at seismic stations in the Chugoku district, southwest Japan. The phase from intermediate-depth earthquakes has apparent velocity close to that of S wave in the Philippine Sea (PHS) plate, but at epicentral distance of 100–250km it arrives earlier by about 2.5s than the S wave propagated as a head wave along the upper boundary of the HPS plate. Thus we interpreted the phase as Sp wave into which the S wave refracted upward after traveling in the high-velocity PHS plate was converted at a boundary while propagating on a ray path between the plate and seismic station. The precursory phase to S wave from deep-focus earthquakes was also identified as Sp wave that was caused by conversion of the direct S wave into P wave, because the S–Sp times were independent of epicentral distance and focal depth and the direction of horizontal particle motion of the phase almost agreed with the azimuth direction of the epicenter. The Sp conversion interface was located at the upper boundary of the PHS plate. Further, it was demonstrated that a thin low-velocity layer should overly just above the PHS plate in order to explain both the observed difference in polarity of the S and Sp waves and the amplitude ratio of the Sp wave to the direct S wave.