Ratio Of Wave Amplitude Research Articles

Classification of seismic events using linear discriminant function (LDF) in the Sakarya region, Turkey

The Sakarya prefecture is an interesting area with various seismicity types. This activity comes from earthquakes occurring at the North Anatolian Fault Zone and from a few quarry blast areas in the region. These quarry blast recordings produce errors in the determination of active faults and mapping of the microearthquake activity. Therefore, to recognize the tectonic activity in the region, we need to be able to discriminate between earthquakes and quarry blasts in the catalogues. In this study, a statistical analysis method (linear discriminant function) has been applied to classify seismic events occurring in the Sakarya region. We used 110 seismic events that were recorded by Sakarya University Seismic Station between 2012 and 2014. Time and frequency variant parameters, maximum S wave and maximum P wave amplitude ratio (S/P), the spectral ratio (Sr), maximum frequency (fmax), and total signal duration of the waveform were used for discrimination analyses. The maximum frequency (fmax) versus time duration of the seismic signal gives a higher classification percentage (94%) than the other discriminants. At the end of this study, 41 out of 110 events (44%) are determined as quarry blasts, and 62 (56%) are considered as earthquakes.

Reflection and transmission of elastic waves at an interface with consideration of couple stress and thermal wave effects

The reflection and transmission of the thermo-elastic coupled waves at an interface of two different couple stress elastic solids are studied in this paper. Based on the Green-Lindsay theory, the governing equations and the constitutive equations are derived. Different from the classic elastic solid, the interface conditions include the surface couple, the rotation angle, the heat flux and the temperature change. The interface conditions are used to obtain the linear algebraic equations set from which the amplitude ratios of reflection and transmission waves to the incident wave can be determined. Then, the normal energy flux conservation is used to validate the numerical results. At last, the influences of two characteristic relaxation times and the five kinds of thermally and micromechanically interface conditions are discussed based on the numerical results. It is found that the thermal wave effects affect only the longitudinal wave while the couple stress effects affect only the transverse waves. The thermo-elastic coupling makes the longitudinal wave and the thermal wave not only dispersive but also attenuated.

Exact Cnoidal Solutions of the Extended KdV Equation

The KdV equation can be derived in the shallow water limit of the Euler equations. Over the last few decades, this equation has been extended to include both higher order effects (KdV2) and an uneven river bottom. Although this equation is not integrable and has only one conservation law, exact periodic and solitonic solutions exist for the even bottom case. The method used to find them assumes the same function forms as for KdV solutions. KdV2 equation imposes more constraints on parameters of solutions. For soliton case KdV2 solution occurs for particular ratio of wave amplitude to water depth only. For periodic case physically relevant solutions are admissible only for two narrow intervals of elliptic parameter $m$. For a range of $m$ near one the cnoidal waves are upright as expected, but are inverted in $m$ region close to zero. Properties of exact solutions of KdV and KdV2 are compared.

Abstract P294: Greater Peripheral Vasoconstriction During Mental Stress Predicts Adverse Cardiovascular Outcomes

Introduction: Peripheral arterial vasoconstriction during mental stress (MS) has been associated with mental stress-induced myocardial ischemia, which in turn has been linked with worse cardiovascular outcomes. It is unknown whether the magnitude of peripheral vasoconstriction with MS is predictive of long term outcomes. Hypothesis: We hypothesized that greater peripheral arterial vasoconstriction during MS would be associated with adverse events among patients with coronary artery disease (CAD). Methods: Four hundred sixty-three patients with stable CAD and normal left ventricular function, (age 63±9, 75% male, 27% Black, EF 60±8 %) underwent MS testing with a standardized public speaking stressor. Digital pulse wave amplitude was continuously measured at baseline and during MS using peripheral arterial tonometry (PAT), and the PAT ratio of pulse wave amplitude (during mental stress/ baseline) was calculated. Cox proportional hazard models were calculated to examine the association between the PAT ratio and outcomes. Results: Median PAT ratio during MS was 0.68, indicating 32% average constriction with MS compared to rest. Subjects with greater peripheral constriction [low (<median) PAT ratio] were more likely to be male (80% vs. 70%, P=0.008) compared to those with PAT ratio ≥median, but their risk factor profiles were similar. During 2.8±0.5 year follow-up, 64 patients had adverse cardiac events including 7 cardiovascular deaths, 19 MI, and 54 revascularization events. After adjusting for age, sex, race, hypertension, diabetes, current smoking status, and prior MI, those with low PAT ratio had a greater risk of CV death/MI (HR[hazard ratio] 2.49, 95% CI [1.04-5.99]) and CV death/MI/revascularization (HR 1.77, 95% CI [1.03-3.04]) compared to those with high PAT ratio. Conclusion: Greater peripheral arterial vasoconstriction with MS is associated with a higher risk of adverse cardiovascular outcomes in patients with CAD.

The Effect of Platinum on β-NiAl/α-Al2O3 Interfacial Tensile Stress: A Combined Ab Initio DFT and Mechanics-Based Model Study

The beneficial effect of adding Pt in diffusion β-NiAl coating on reducing the tensile stress normal to the coating/α-Al2O3 scale interface has been investigated using a combination of ab initio density functional theory (DFT), phonon dispersion theory and mechanics-based interfacial stress modeling. The coefficient of thermal expansion (CTE) for Pt, β-NiAl and β-NiAl-6.25 at% Pt was calculated using the total energy DFT combined with the phonon dispersion theory. The calculated CTE of β-NiAl and β-NiAl-6.25 at% Pt and experimentally measured CTE of α-Al2O3 were used to evaluate the tensile stress of the undulated β-NiAl/α-Al2O3 and β-NiAl-6.25 at% Pt/α-Al2O3 interfaces resulting from the CTE mismatch between the coating and the oxide scale during cooling from elevated temperatures. It was found that the addition of Pt to β-NiAl is capable of lowering the interfacial tensile stress as a result of the reduced CTE of the Pt-modified β-NiAl coating, thus beneficial for improving thermal cyclic durability of the coating. The calculated results showed that the interfacial tensile stress is a function of oxide scale thickness and the interfacial wave amplitude and wavelength of an undulated interface. A thicker oxide scale and a rougher interface with a larger ratio of wave amplitude versus wavelength yield higher interfacial tensile stresses during thermal cycling. The addition of 6.25 at% Pt to β-NiAl coating reduces the coating/oxide scale interfacial tensile stress by about 27% over a wide range of scale thickness and interfacial wave amplitude and wavelength.

ST segment change and T wave amplitude ratio in lead aVR associated with coronary artery disease severity in patients with non-ST elevation myocardial infarction: A retrospective study.

Non-ST elevation myocardial infarction (NSTEMI) severity is difficult only with electrocardiogram (ECG). In most cases, NSTEMI patients are followed with cardiac enzymes without early invasive intervention if no severe chest pain exists in the emergency department (ED) or coronary intensive care unit (CICU).Our aim was to evaluate association between CAD severity and ST segment change in lead aVR (STaVR)/T wave amplitude in lead aVR (TAaVR) ratio in patients with NSTEMI.We included 306 patients with NSTEMI in the ED between 2015 and 2016. STaVR and TAaVR values were measured from 12-derivation ECG underwent on admission to the ED. The absolute values of STaVR and TAaVR were calculated and the following were obtained; ratio 1:|STaVR|/|TAaVR|, ratio 2:|TAaVR|/|STaVR|, and ratio 3: by dividing the variable with larger absolute value to other variable with smaller absolute value (|larger value|/|smaller value|). The SYNTAX score (SS) was calculated from coronary angiography in all patients.In analysis of the bivariate correlation between SS and ratios; significantly positive, strongly with ratio 3 (r = 0.692, P < .001), and only ratio 3 was determined to be an independent predictor for SS in linear regression analysis (OR: 0.642, 95% CI: 0.432–0.853, P = .001).Severity of CAD may be estimated by evaluating STaVR and TAaVR ratio in patients with NSTEMI.

K-complex morphological features in male obstructive sleep apnea-hypopnea syndrome patients

This study characterized the differences in K-complex (KC) morphology features between obstructive sleep apnea-hypopnea syndrome (OSAHS) patients and healthy controls and analyzed the effect of respiratory events on KC morphology. We enrolled 42 male subjects (21 OSAHS patients and 21 age-matched healthy controls) who underwent overnight polysomnography. KCs in stage N2 were manually identified. We found that KCs in healthy controls had larger negative and whole amplitudes, longer durations, and smoother positive waves than OSAHS patients but smaller positive amplitudes. Most features showed highly significant differences after Bonferroni correction (p<0.001/3). After separating out the KCs associated with respiratory events in OSAHS patients, the differences between the groups remained but were relatively smaller. In OSAHS patients, compared with the spontaneous KCs not evoked by obvious factors, the KCs occurring after respiratory events had larger amplitudes, steeper slopes, larger negative wave amplitude and duration ratios. KCs occurring during respiratory events showed lower amplitudes and shorter durations. These results may reveal the impact of respiratory events on sleep and brain function.

Influences of a visco-elastically supported boundary on reflected waves in a couple-stress elastic half-space

The reflection of elastic waves at the surface of a couple-stress elastic half-space with a viscoelastic support is studied in this paper. Different from the classical elastic solid, there are: a non-dispersive dilatational propagating wave, a dispersive transverse propagating wave and a dispersive evanescent wave in a couple-stress elastic solid. The boundary conditions at the visco-elastically supported surface of a couple-stress elastic half-space include the couple-stress vector and the rotation vector, which disappear in the classical elastic solid. They are used to obtain a set of linear algebraic equation, from which the amplitude ratios of reflection waves with respect to the incident wave can be determined. Then, the reflection coefficients in terms of energy flux ratios are calculated numerically, and the normal energy flux conservation is used to validate the numerical results. At last, the influence of the boundary parameters that reflect the mechanical behavior of a viscoelastic support on the amplitude ratio, the phase shift and the energy partition of reflection waves are discussed based on the numerical results. Both the incident longitudinal displacement wave (the P-wave) and incident transverse displacement wave (the SV-wave) are considered. It is found that the instantaneous elasticity and the delayed viscosity of a viscoelastic support have different influences on the reflection waves.

Reflection and transmission of elastic waves through a couple-stress elastic slab sandwiched between two half-spaces

The reflection and transmission of elastic waves through a couple-stress elastic slab that is sandwiched between two couple-stress elastic half-spaces are studied in this paper. Because of the couple-stress effects, there are three types of elastic waves in the couple-stress elastic solid, two of which are dispersive. The interface conditions between two couple-stress solids involve the surface couple and rotation apart from the surface traction and displacement. The nontraditional interface conditions between the slab and two solid half-spaces are used to obtain the linear algebraic equation sets from which the amplitude ratios of reflection and transmission waves to the incident wave can be determined. Then, the energy fluxes carried by the various reflection and transmission waves are calculated numerically and the normal energy flux conservation is used to validate the numerical results. The special case, couple-stress elastic slab sandwiched by the classical elastic half-spaces, is also studied and compared with the situation that the classical elastic slab sandwiched by the classical elastic half-spaces. Incident longitudinal wave (P wave) and incident transverse wave (SV wave) are both considered. The influences of the couple-stress are mainly discussed based on the numerical results. It is found that the couple-stress mainly influences the transverse modes of elastic waves.

Student experiment for measure of target strength

The target strength is a measurement of the reflection coefficient of a sonar target. Its value and feature is very important to detection and identification in active sonar, especially for fish by fishery acoustic students. A steel cylindrical shell is used as the target, whose outer diameter 194 mm, inner diameter 184 mm, length 500 mm, and both end closed covers with thickness 4 mm. A broadband transducer is selected to directionally project sound wave and a hydrophone receives the reflection wave from the target. The transducer and receiver are located at 5 m and 4 m from the target with the same depth 5 m in the water. When single frequency pulses are transmitted with signal interval frequency 50 Hz, the target strength is calculated by amplitude ratio of target echo and incidence wave at different frequencies. The result is compared with theoretical value for an infinite elastic cylindrical shell and finite length elastic cylindrical shell. This experiment will give a strategic guidance to understand what target strength is, how to understand it, and why we need it. [Work supported by National Natural Science Foundation of China (Grant No. 41374147).]

A simple independent prognostic electrocardiography parameter in first acute anterior myocardial infarction; Precordial total Q wave/precordial total R wave

BackgroundWe investigated the prognostic value of precordial total Q wave amplitude/precordial total R wave amplitude ratio (Q/R) in patients with first acute anterior MI treated with primary percutaneous coronary intervention (PPCI). MethodsWe evaluated the in-hospital prognostic impact of Q/R on 354 patients with first acute anterior MI. Patients were stratified by tertiles of admission Q/R, clinical outcomes were compared between those groups. ResultsIn-hospital univariate analysis revealed notably higher rates of in-hospital death for patients in tertile 3, as compared to patients in tertile 1 (OR 9.7, 95% CI 2.8–33.5, p. ConclusionQ/R in admission ECG in patients with first acute anterior MI provide an independent prognostic marker of in-hospital outcomes.

HIDDEN HEARING LOSS AND COGNITIVE MEASURES IN HEALTHY ELDERS

Epidemiological evidence shows an association between presbycusis or age-related hearing loss and cognitive decline in elderly people. Presbycusis subjects with audiometric hearing thresholds (PTA) worse than 40 dB are more likely to develop cognitive decline. The mechanisms of this epidemiological association are unknown. Here we propose that hidden hearing loss (HHL), that is the loss of auditory-nerve neurons without alterations at the audiometric thresholds, is an important factor linking presbycusis and cognitive decline. HHL can be assessed using supra-thresholds auditory brainstem responses (ABR). Analyze supra-thresholds ABR responses and cognitive measures in healthy elders. 52 Persons from the ANDES study ≥65 years without dementia (MMSE>24) with normal hearing thresholds (PTA<20dB, n=13), with mild (PTA: 20–39dB, n=29) or moderate presbycusis (PTA≥40dB, n=10), were evaluated using a comprehensive neuropsychological assessment and with the self-reported questionnaire of hearing handicap inventory for the elderly (HHIE). Amplitudes and latencies of ABR waves I and V were obtained at supra-thresholds levels. The ratio between wave I/V was computed as a measure of HHL. These ABR variables were analyzed and correlated with cognitive tests. Those with moderate presbycusis had significant higher scores in the HHIE (F(2)=5.80, p=0.005). The MMSE score correlated with the amplitude (r=0.40, p=0.006) and latency (r=-0.38, p=0.009) of wave I, and the amplitude ratio (waves I/V) (r=0.38, p=0.009) of the right ear. The Boston test correlated with bilateral amplitude ratios (wave I/V) of wave I (right: r=0.34, p=0.023; left: r=0.37, p=0.013). The Wisconsin card sorting test correlated with the amplitude of right ABR waves I (r=0.30, p=0.03) and V (r=0.32, p=0.03). The Corsi test with (r=0.33, p=0.28) and without (r=0.33, P=0.03) noise correlated with the amplitude ratio of wave I/V in the left ear. Auditory nerve supra-thresholds responses correlate with several cognitive measures in healthy elderly subjects. These preliminary results should be confirmed with a larger sample of presbycusis patients. Funded by Proyecto Anillo ACT1403, Fondecyt 1140423, and Fondecyt 1161155.

Effects of pile rows on vibration reduction in nearly saturated soil

This paper presents an analysis about the vibration reduction effects by a barrier in a nearly saturated soil medium. The barrier is assumed to consist in an arbitrary distribution of parallel cylindrical piles embedded in an infinite nearly saturated soil. Based on the equations governing the motion of nearly saturated soil, the complex wave numbers and amplitude ratios between the liquid phase and solid phase are first derived according to the Helmholtz decomposition theorem. With the aid of the Graff’s addition theorem, the unknown multiple complex scattering coefficients by an arbitrary configuration of piles as barriers are determined by taking an advantage of the boundary conditions at pile-soil interfaces and the linear independence of trigonometric functions. Then the corresponding expressions for the nearly saturated soil displacements at both sides of the pile rows can be obtained. The numerical results show that soil saturation degree and permeability exert significant influences on the isolation effectiveness of pile rows, and that the distance between neighboring rows is crucial for the isolation effectiveness. The isolation rules can provide useful guidelines to the design of pile rows as barriers in nearly saturated soil.

Influence of heat transfer on the peristaltic transport of Walters B fluid in an inclined annulus

The aim of the present analysis is to investigate the effects of endoscope and heat transfer on the peristaltic flow of an incompressible Walters B fluid in an inclined tube. The fluid fills the gap between coaxial uniform tubes, such that the inner tube is rigid, circular and outer tube has sinusoidal wave travelling down its wall. The governing equations for Walters B fluid model are considered in cylindrical polar coordinates in moving frame of reference. The governing coupled partial differential equations are solved analytically employing regular perturbation method. The graphical results have been discussed for velocity, pressure gradient, pressure difference, frictional force, temperature and trapping phenomena. Four different wave forms have been considered for investigation. Trapping phenomena has been presented for different wave forms. It is observed that the pressure gradient is an increasing function of volume flow rate, heat generation parameter and inclination angle. The pumping rate increases from horizontal tube to vertical tube. Best pumping can be seen when the radius of the endoscope increases. The size of the trapping bolus increases with increase of wave amplitude ratio.

Wave attenuation mechanism of cross-plates applied in landslide-induced tsunami in river course

Since the impounding of the Three Gorges Reservoir, the channel of the Yangtze River has become a busy watercourse and the probability of landslide-induced tsunamis has increased. In the case of landslide-induced tsunamis in the Three Gorges Reservoir, even after shipping closures in advance, there are still facilities and objects in urgent need of protection within the risk zone of the watercourse, such as wharfs, marine fueling stations, berthed ships. The emergency protection against and decay of landslide-induced tsunamis in inland watercourses is a new challenge. In this study, 37 sets of wave decay experiments were conducted with the hydromechanics numerical method. The wave decay efficiencies of common simple structures including submerged horizontal plate, horizontal plate on the water surface, inclined thin plate and cross-plates in coastal areas were compared and analyzed. Cross-plates structure showed better wave decay capacity than other simple plates. The wave decay performance of cross-plates was related to five modes of energy dissipation and transformation, namely run-up/run-down, overtopping, reflecting, return flow and disturbed wave orbital path. The type of wave had little relation with the decay performance of cross-plates, but a strong correlation with cross-plates structure, especially the height of the vertical emerged plate. The best decay performance was observed when the ratio of wave amplitude to emerged vertical plate height was between 1 and 1.5, which can reduce up to about 80% of the incoming wave amplitude. Finally, the emergency way of cross-plates applied to the decay of landslide-induced tsunami in river course is discussed. This study provides a conceptual reference for related studies to practice the attenuation of landslide-induced tsunami in reservoirs.

Reflection of elastic waves at the elastically supported boundary of a couple stress elastic half-space

The reflection elastic waves at the elastically supported boundary of a couple stress elastic half-space are studied in this paper. Different from the classical elastic solid, there are three kinds of elastic waves in the couple stress elastic solid, and two of them are dispersive. The boundary conditions of a couple stress elastic half-space include the couple stress vector and the rotation vector which disappear in the classical elastic solids. These boundary conditions are used to obtain a linear algebraic equation set, from which the amplitude ratios of reflection waves to the incident wave can be determined. Then, the reflection coefficients in terms of energy flux ratios are calculated numerically, and the normal energy flux conservation is used to validate the numerical results. Based on these numerical results, the influences of the boundary parameters, which reflect the mechanical behavior of elastic support, on the reflection energy partition are discussed. Both the incident longitudinal wave (the P wave) and incident transverse wave (the SV wave) are considered.

Electroacupuncture improves gait locomotion, H-reflex and ventral root potentials of spinal compression injured rats.

This study explored the effect of electroacupuncture stimulation (EA) on alterations in the Hoffman reflex (H-reflex) response and gait locomotion provoked by spinal cord injury (SCI) in the rat. A compression lesion of the spinal cord was evoked by insufflating a Fogarty balloon located in the epidural space at the T8-9 spinal level of adult Wistar male rats (200-250 gr; n=60). In different groups of SCI rats, EA (frequencies: 2, 50 and 100Hz) was applied simultaneously to Huantiao (GB30), Yinmen (BL37), Jizhong (GV6) and Zhiyang (GV9) acupoints from the third post-injury day until the experimental session. At 1, 2, 3 and 4 post-injury weeks, the BBB scores of the SCI group of rats treated with EA at 50Hz showed a gradual but greater enhancement of locomotor activity than the other groups of rats. Unrestrained gait kinematic analysis of SCI rats treated with EA-50Hz stimulation showed a significant improvement in stride duration, length and speed (p<0.05), whereas a discrete recovery of gait locomotion was observed in the other groups of animals. After four post-injury weeks, the H-reflex amplitude and H-reflex/M wave amplitude ratio obtained in SCI rats had a noticeable enhancement (217%) compared to sham rats (n=10). Meanwhile, SCI rats treated with EA at 50Hz manifested a decreased facilitation of the H-reflex amplitude and H/M amplitude ratio (154%) and a reduced frequency-dependent amplitude depression of the H-reflex (66%). In addition, 50 Hz-EA treatment induced a recovery of the presynaptic depression of the Gs-VRP evoked by PBSt conditioning stimulation in the SCI rat (63.2±8.1%; n=9). In concordance with the latter, it could be suggested that 50 Hz-EA stimulation reduced the hyper-excitability of motoneurons and provokes a partial improvement of the locomotive performance and H reflex responses by a possible recovery of presynaptic mechanisms in the spinal cord of experimentally injured rats.

A pharmacological approach in newly established retinal vein occlusion model

The mechanism underlying the effects of anti-vascular endothelial growth factor (VEGF) antibody in retinal vein occlusion (RVO) treatment is poorly understood, partly due to the lack of RVO animal models that mimic clinical pathology. The aims of this study were to establish a suitable RVO model, clarify the pathogenic mechanisms, and evaluate the effects of anti-VEGF antibody in the model. Mouse retinal veins were occluded by laser photocoagulation after rose bengal injection. Reduction of the b/a wave amplitude ratio, retinal nonperfusion, cystoid edema, and hard exudates were observed after occlusion, and expression of RVO-related genes was altered. Administration of anti-VEGF antibody immediately, or 7 days, after occlusion resulted in reduction and increase of the nonperfused area, respectively. We conclude that the present model will be useful for clarification of the pathogenic mechanisms, and that the timing of anti-VEGF antibody administration is important for the successful amelioration of retinal nonperfusion.

Effect of initial conditions on wave motion in density-stratified three-layer liquid with free surface

The ratio of amplitudes of waves generated by different interfaces in stratified inhomogeneous liquid is analytically studied. The amplitudes of waves generated by the second interface depend on the initial conditions and can be greater or less than the amplitudes of waves generated by the third interface. The amplitude ratio of the external and internal waves significantly depends on the ratio of liquid densities and layer thicknesses. Substantial effect of the initial conditions is manifested as a variation in the ratio of the amplitudes of external and internal waves and the amplitude ratio of waves generated by different interfaces.

In-plane wave propagation through a microstretch slab sandwiched by two half-spaces

Abstract The problem of in-plane wave propagation through a sandwiched slab which is governed by the micro-stretch elasticity is discussed in this paper. Different from the classical elastic solid, the mass particles in a micro-stretch solid can undergo the micro-rotation and the micro-stretch in addition to the displacement. As a result, there are five kinds of dispersive waves in a micro-stretch medium. The interface conditions between two microstretch solids are also different from that between two classic elastic solids. By incorporating the non-traditional interface conditions at two interfaces, a set of algebraic equations is obtained from which the amplitude ratios of reflection and transmission waves can be obtained. A numerical example is provided and the energy conservation law is used to check the numerical results. Based on the numerical results, the influences of the microstretch constants and the non-dimensional thickness (relative to the wavelength) of the slab, and the four kinds of possible interface conditions between the micro-stretch slab and the classic elastic half-spaces are discussed. Some special cases as the degeneration of present model are discussed.