Average Wave Velocity Research Articles

Soil properties and applications review with NERA (nonlinear earthquake site response analyses) in İstanbul-MARMARAY Project between Kazliçeşme to Sirkeci

Over the course of history, Marmara region in northwestern Turkey has been the site of numerous destructive earthquakes. Based on historical and instrumental earthquake records, the Marmara sea region is one of the most seismically active regions of the Eastern Mediterranean. The Marmara region is under the influence of the western part of the North Anatolian Fault Zone and the N–S extensional regime of Western Turkey. Therefore, the earthquake risk analysis is very important for the MARMARAY Project. The 76-km-long MARMARAY Project is an important project not only for Turkey but also for the world because it joins the two continents through railway. It will also serve for a comfortable and healthy way of environment, providing a contemporary solution for urban transportation. In this paper, using average wave velocities in layers, thickness, density and formation data based on the PS logs, and seven different boring logs located in different geological regions with depth range 43–60 m from the ground surface, ground response functions have been obtained. The influences of nonlinearity on the site response analysis have been summarized and evaluated with a numerical example. Based on the soil profiles transferred to nonlinear earthquake site response analyses of layered soil deposits (NERA) software, the rock and soil records of August 17, 1999 Kocaeli earthquake from a recording site in Besiktas town of Istanbul, response and design spectrums that may be considered crucial in case of an earthquake have been obtained. The acceleration record having a PGA value of 0.04287 g in east–west component has been used as an input motion to sublayers (i.e., sand, gravel, clay) with constant damping ratio of 5 %, using NERA program. The study also provides a critical overview of the site response analysis of the field under interest.

A new approach to solve the problems of seismic vibrations for periodically nonuniform buried pipelines

The method proposed by E.A. Il’yushina is used to study the longitudinal vibrations of segmented buried pipelines. It is shown that the averaged wave velocity in a periodically nonuniform pipeline is specified by the effective static moduli of the periodicity cell and that, in the case of using a vibration damping material made of rubber or soft metal at joints between pipes, this velocity can be much less than the velocity of longitudinal waves in the main pipe. The last fact makes it reasonable to consider supersonic regimes in the problems of seismic vibrations when the wave velocity in a pipeline is less than the wave velocity in the soil.

Comment on “Structural phase transition, electronic and elastic properties in TlX (X = N, P, As) compounds: Pressure-induced effects” [Comput. Mater. Sci. 50 (2010) 203–210

Recently, L. Shi, Y. Duan and L. Qin have published a paper in Computational Materials Science 50 (2010) 203–210. They have studied the pressure induced phase transition and structural, electronic and elastic properties of TlX (X=N, P, As) compounds using the plane-wave pesudopotential (PW-PP) method. But it is to be noted that the numerical values of the average (vm) wave velocities, and the Debye temperature ϑD of TlX (X=N, P, As) semiconductors obtained by Shi et al. (2010) seem to be inaccurate.In the present work, we have recalculated and gave the right numerical values of the average (vm) wave velocities and the Debye temperature ϑD of TlX (X=N, P, As) semiconductors, based on the lattice parameters and the elastic constants obtained in their work.

Brittle to Ductile Transition Dependence upon the Transition Pressure of MB_2 (M=Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) Compounds

First principles calculations were performed to investigate the electronic and elastic properties of the group IV to group VI transition metal borides. As a result, the electronic bands and the density of states (DOS) at the Fermi level were obtained, also the independent elastic constants (C_(ij)) of hexagonal MB_2 (M=Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) at zero pressure, the bulk moduli (B), the shear moduli (G), and the B/G ratio were also obtained. The brittle/ductile behavior of the group IV to group VI transition metal borides were evaluated and analyzed in comparison with the available data. The Debye temperature for ZrB_2 was calculated from the average elastic wave velocity obtained from the shear and bulk moduli. The calculated elastic properties are found to be in good agreement with the experimental values. The volume expansion coefficient _ versus temperature and pressure for ZrB_2 are discussed. The dependencies of the bulk, shear, Young's modulus, Poisson's ratio, and sound velocities V_l, V_t on the pressure P for ZrB_2 were also analyzed.

Cardiac dysfunction in liver cirrhosis: A tissue Doppler imaging study from Egypt.

Background:Patients with liver cirrhosis suffer from various cardiac abnormalities, which may influence their outcome. Tissue Doppler recording of the mitral and tricuspid annular diastolic velocities can be used to assess diastolic function accurately. There has been very little published information regarding RV diastolic function in liver cirrhosis. This study is aimed at evaluating right and left ventricular systolic and diastolic functions in post hepatitis C liver cirrhosis patients using conventional echocardiography and tissue Doppler imaging.Methods:This study was conducted on 75 adults from inpatient and outpatient services of the Theodor Bilharz Research Institute (TBRI) hospital. They were divided into two groups: Group 1 included 50 patients with post hepatitis C liver cirrhosis; and Group 2 included 25 normal adults serving as a control group. All patients and normal volunteers were subjected to clinical examination, laboratory evaluation, abdominal ultrasonography and echocardiographic studies with tissue Doppler imaging for evaluation of left and right ventricular systolic and diastolic functions.Results:The mitral flow showed significant increase in A wave velocity, as well as DT and IVRT with a significant decrease in E/A ratio in Group 1 compared to Group 2 (P<0.01). The tricuspid flow also showed a significant increase in A wave velocity (P<0.01) and DT (P<0.05) in addition to a significant decrease in E wave velocity and E/A ratio (P<0.01) in Group 1 as compared to Group 2. At the mitral annulus, we found a significant increase in average Aa velocity, E/Ea ratio and average systolic wave velocity S, in addition to a statistically significant decrease in the average Ea velocity and average Ea/Aa (P<0.01) in Group 1 as compared to Group 2. At the tricuspid annulus, there were significant increases in the average Aa velocity (P<0.01), S velocity (P<0.01) and E/Ea (P<0.05) together with a statistically significant decrease in the average Ea/Aa and average Ea velocity (P<0.01) in Group 1 compared to Group 2.Conclusion:It is important to evaluate the cardiovascular function in every patient with cirrhosis, especially if the patient is a candidate for any intervention that may affect haemodynamics.

Structural, elastic, electronic and optical properties of the quaternary nitridogallate LiCaGaN2: First-principles study

First-principles density functional theory calculations were performed to predict some of the not yet explored physical properties of the monoclinic quaternary nitridogallate LiCaGaN2. The calculated lattice parameters, including the lattice constants, angle β and internal atomic coordinates, are in excellent agreement with the corresponding measured ones, proving the reliability of the chosen theoretical approach. The equation of state, pressure dependence of the lattice constants, unit cell volume, angle β and bond-lengths were explored in detail. The single-crystal and polycrystalline elastic constants and their pressure dependence were numerically estimated. The mechanical stability, ductility/brittleness, average elastic wave velocity, Debye temperature and elastic anisotropy were also assessed. The electronic structure and its evolution with external applied hydrostatic pressure were explored. The bonding character was demonstrated by calculating the site-projected density of states, charge density and effective Mulliken charges of all ions. The effective masses of the charge-carriers were numerically estimated. The complex dielectric function, refractive index, extinction coefficient, absorption coefficient, reflectivity and electron energy-loss function spectra were calculated for different polarizations of the incident light. Pressure dependence of the static dielectric constant, static refractive index and static reflectivity are also reported. To the best of our knowledge, this is the first attempt to explore the aforementioned physical properties for the title material.

Sound velocities and thermal properties of BX (X=As, Sb) compounds

The sound velocities and thermal properties of Boron-Arsenide (BAs) and Boron- Antimonide (BSb) materials have been predicted with the help of the empirical elastic constants which are taken from our previous work which is accepted to publication in International Journal of Scientific World. The longitudinal, transverse and average elastic wave velocities, the Debye temperature, the melting temperature, the thermal conductivity, the linear thermal expansion coefficient and finally the Gruneisen parameter are predicted and analyzed in comparison with the available theoretical data of the literature. Our obtained results are in general in very good agreement with the previous experimental and theoretical data of the literature.

Thermal and elastic properties of Sr1−x A x CoO3 (A=Zn and Ho)

We have investigated the elastic and thermal properties for Sr1−x A x CoO3 (A=Zn, Ho, and 0≤x≤0.4) probably for the first time, by using the modified rigid ion model (MRIM). The computed elastic constants (C 11, C 12, C 44) are the first report on them. Using these elastic constants, we have computed other related elastic properties like the Bulk modulus (B), Young’s modulus (Y), Shear modulus (G), Poisson’s ratio (σ), Lame’s parameter (μ, λ), transverse, longitudinal and average wave velocity (υ t, υ l, υ m) and Anisotropy parameter (A). Furthermore, by the elastic stability criteria, we predict that Sr1−x A x CoO3 (A=Zn, Ho, and 0≤x≤0.4) are mechanically stable and belongs to metallically bonding materials. Moreover, the thermodynamic properties such as the thermal expansion coefficient (α), cohesive energy (ϕ), molecular force constant (f), Reststrahlen frequency (υ), Debye temperature (θ D), and Gruneisen parameter (γ) have also been predicted. Besides, the variations of specific heat with temperature are reported for a wide range. To our knowledge, some of the properties are being reported for the first report on these materials.

Time‐wave velocity analysis for early earthquake damage detection in buildings: application to a damaged full‐scale RC building

SummaryAn algorithm for time velocity analysis of building response is presented, which identifies the wave velocity of vertically propagating waves through the building and detects their changes. The algorithm is intended for use in SHM systems for rapid assessment of the structural health and integrity following an earthquake. The velocities are identified by an interferometric algorithm, which involves least squares fit of pulses in impulse response functions. An important feature of this method is that it is not sensitive to the effects of soil–structure interaction. The algorithm is applied to a 12‐story RC building in Los Angeles, lightly damaged by the San Fernando 1971 earthquake. The results of the time velocity analysis are critically compared with results of analysis of input power, interstory drift, and instantaneous frequency. The identified average vertical wave velocity was initially ~140 m/s for the NS and ~110 m/s for the EW response and reduced by ~26% and 32%, respectively. The detected reduction of the fundamental frequency of vibration was larger (~44% for the NS and 48% for the EW response). The difference is interpreted to be due to softening of the soil–foundation system, to which the identified frequency of vibration is sensitive. The change was larger in the lower half of the building (~31% for the NS and ~37% for the EW response) as compared with the upper half (~24% for the NS and ~27% for the EW response), consistent with the observed damage. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Ab initio prediction of the structural, electronic, elastic and thermodynamic properties of the tetragonal ternary intermetallics XCu2Si2 (X = Ca, Sr)

Structural parameters, electronic structure, elastic constants and thermodynamic properties of the tetragonal ternary intermetallics CaCu2Si2 and SrCu2Si2 are investigated theoretically for the first time using the plane-wave ultra-soft pseudopotential method based on the density functional theory. The calculated equilibrium structural parameters agree well with the existing experimental data. Pressure dependence of the structural parameters is also explored. Analysis of the band structure, total and site-projected l-decomposed densities of states and valence charge distributions reveals the conducting character of both considered materials with a mixture of ionic-covalent chemical bonding character. Pressure dependences of the single-crystal elastic constants C ij for CaCu2Si2 and SrCu2Si2 are explored. The elastic wave velocities propagating along the principal crystallographic directions are numerically estimated. The elastic anisotropy is estimated and further illustrated by 3D-direction-dependent of the Young’s modulus. A set of some macroscopic elastic moduli, including the bulk, Young’s and shear moduli, Poisson’s coefficient, average elastic wave velocities and Debye temperature, were calculated for polycrystalline CaCu2Si2 and SrCu2Si2 from the C ij via the Voigt-Reuss-Hill approximations. Through the quasiharmonic Debye model, which takes into account the phonon effects, the temperature and pressure dependencies of the bulk modulus, unit cell volume, volume thermal expansion coefficient, Debye temperature and volume constant and pressure constant heat capacities of CaCu2Si2 and SrCu2Si2 are explored systematically in the ranges of 0–40 GPa and 0–1400 K.

Mechanical, electronic and thermodynamic properties of C14-type AMg2 (A = Ca, Sr and Ba) compounds from first principles calculations

Using first principles total energy calculations within the generalized gradient approximation (GGA), we have investigated the mechanical and thermodynamics properties of C14-type Laves phases AMg2 (A=Ca, Sr and Ba). Our results of equilibrium lattice parameters and formation enthalpy agree closely with previous experimental results. In particular we have discussed the thermodynamic stabilities and mechanical anisotropies of these phase structures. The polycrystalline elastic moduli have been deduced by Voigt–Reuss–Hill arithmetic approximation. Subsequently, the ductility and brittleness are characterized with the estimation from Pugh’s rule (B/G) and Poisson’s ratio. Additionally, the Debye temperature is calculated from the average elastic wave velocity obtained from bulk and shear moduli. The calculations of density of states and charge density difference are performed to reveal the underlying mechanism of electronic structure. Finally, variations of thermodynamic properties with temperature are predicted by calculating phonon frequencies combined within the quasi-harmonic approximation.

Investigations on the structural, electronic, elastic and thermodynamic properties of niobium silicide under high temperature and pressure

A first principles investigation on the structural, electronic and elastic properties of NbSi2 has been calculated using the plane wave pseudo-potential density functional theory (DFT) method. The lattice constants and elastic constants are obtained. The characters of the band structure and the density of states of niobium silicide (NbSi2) are analyzed, which shows that NbSi2 is metallic. The bulk, shear and Young’s modulus for NbSi2 are also calculated. The Debye temperature is calculated from the average elastic wave velocity obtained from the shear and bulk modulus. The thermodynamic properties including the heat capacity CV and CP, thermal expansionα, entropy S and Grüneisen parameterγhave been calculated at temperatures from 0 to 2100K and pressures from 0 to 30GPa using the quasi-harmonic Debye model. We also found that the present work can give a reference to those not to be experimentally investigated.

Effect of cinacalcet treatment on vascular arterial stiffness among peritoneal dialysis patients with secondary hyperparathyroidism

Although calcimimetics cinacalcet can reduce parathyroid hormone level and control secondary hyperparathyroidism in end-stage renal disease patients, risk of vascular calcification remains high. Whether cinacalcet can further reduce vascular damage or arterial stiffness is unknown. We studied the effect of cinacalcet in 33 peritoneal dialysis patients with inadequately controlled secondary hyperparathyroidism despite standard treatment. The primary outcome was the aortic pulse wave velocity at 26 and 52 months after cinacalcet treatment. The pulse wave velocity was compared with that of a matched control cohort of 37 peritoneal dialysis patients with secondary hyperparathyroidism. Thirty-three patients completed the cinacalcet treatment, after median dialysis duration of 1.0 year. Significant improvement of parathyroid hormone level was achieved after 52 weeks, from 87.5 ± 28.7 pmol/L to 34.5 ± 45.5 pmol/L (P < 0.0001). Serial carotid-femoral pulse wave velocity did not differ between cinacalcet treatment group and control group (general linear model with repeated measures, P = 0.19). Among patients receiving cinacalcet, the average carotid-femoral pulse wave velocity increased from 10.46 ± 2.12 m/s at baseline to 11.41 ± 2.79 m/s at 52 weeks (P = 0.001). The change in carotid-femoral pulse wave velocity over 1 year had no significant correlation with the final parathyroid hormone level or change in parathyroid hormone level. Among prevalent patients receiving peritoneal dialysis and with hyperparathyroidism, a reduction of 60.6% parathyroid hormone level after cinacalcet treatment for one year did not reduce the carotid-femoral pulse wave velocity.

Improved visualization algorithms for vertical annular flow

Models of annular flow often focus on the liquid film at the periphery of the flow channel. Recent two-region models have used wave intermittency as a measurement of the disturbance wave contribution to gas-to-liquid momentum transfer and pressure loss. Data reduction algorithms for film thickness distribution, from planar laser-induced fluorescence imaging; and disturbance wave intermittency, from high-speed, backlit videos, have been improved. The revised data reduction results are then considered with regard to a recent two-region model. Outputs of average film thickness, pressure gradient, and average wave velocity are modeled with mean absolute errors of 8.70, 17.42, and 19.14 %, respectively.

First-principles calculations of structural, elastic and electronic properties of Li2B12H12

We investigate the structural, elastic and electronic properties of Li2B12H12 using the first-principles method. Our calculations show that the lowest energy structure of Li2B12H12 is monoclinic C2/m type. We take the monoclinic C2/m Li2B12H12 as a representative to carry out the corresponding theoretical studies. The independent elastic constants are successfully obtained from the strain energy–strain curve calculations. The Shear and Young‘s moduli, as well as Poisson‘s ratio for ideal polycrystalline Li2B12H12 are calculated. The shear anisotropic factors and elastic anisotropy of Li2B12H12 are analyzed. The Debye temperature and the average elastic wave velocity are derived from theoretical elastic constants. According to the obtained results, the monoclinic C2/m Li2B12H12 is found to be mechanically stable and brittle at zero temperature and zero pressure. Furthermore, the density of states and electron charge density distributions are studied. The insulator Li2B12H12 is a technologically interesting indirect hydrogen storage material for further studies.

HF Radar detected water wave velocity over the Northern Jiangsu Shoal

High-frequency (HF) radar systems can provide wave velocity and radial current by identifying and tracking frequency shifts in the peaks of the Doppler spectra of the ocean backscatter corresponding to the advection of the Bragg wave. Data used in this study was collected by HF radar experiment for the Northern Jiangsu Shoal in July 2011. A distribution of monthly average wave velocity was generated with data that is quality controlled particularly. The intertidal flat, offshore shoal and tidal channel, associated with low speed area, high speed area and high speed belt respectively, could be distinguished by the HF radar mapped wave velocity distribution. After compared with datasets of field measurement and calculate results, it is revealed that, 1) the relationship between water depth and monthly average wave velocity fits the theory of Airy Wave, 2) large radial currents may rise measurement accuracy of wave velocity, and 3) mismatch of approaching and leaving wave velocity related to complex topography may reduce measurement accuracy.

The first-principles study on physical properties and phase stability of Boron-V (BN, BP, BAs, BSb and BBi) compounds

The physical properties of Boron – group V compounds have been investigated systematically by using density functional theory, based on the full-potential linearized augmented plane-wave method. Generalized gradient approximation is performed to calculate the structural and elastic properties of all studied Boron compounds. We have investigated the phase stability of Boron-V compounds in zinc-blend, rock-salt and wurtzite crystallographic phases. The structural properties such as the equilibrium lattice parameter, bulk modulus and its pressure derivative of Boron-V compounds have been calculated in three phases and compared with other theoretical and experimental works. The elastic properties of the studied compounds are only investigated in the most stable calculated phase. We have obtained Young’s modulus, shear modulus, Poisson’s ratio, anisotropy factor, Kleinmann parameter, wave velocities and melting temperature by the aid of the calculated elastic constants, which are of great technological importance to Boron related compounds. And, we have also found the Debye temperature of the compounds from the average wave velocity. Our results are in reasonable agreement with the available theoretical and experimental data. Detailed comparisons are made with the results obtained in previous theoretical studies and available measured values.

Mild Chronic Kidney Disease Associated with Greater Risk of Arterial Stiffness in Elderly Adults

To assess the association between arterial stiffness and mild and moderate chronic kidney disease (CKD), independent of other cardiometabolic factors in an elderly population. Cross-sectional study. Health examination data from National Cheng Kung University Hospital from 2006 to 2009. Eligible subjects aged 60 and older (N = 1,251). An average bilateral brachial-ankle pulse wave velocity (baPWV) of 1,400 cm/s or greater was defined as high baPWV. Based on the 2003 Clinical Practice Guidelines for Chronic Kidney Disease from the National Kidney Foundation, mild and moderate CKD were defined as CKD Stages 1 and 2 and Stages 3 to 5, respectively. Participants with a baPWV of 1,400 cm/s or greater (n = 1,028) had lower estimated glomerular filtration rates (eGFRs) but higher serum creatinine levels and greater prevalences of mild and moderate CKD, diabetes mellitus, prediabetes mellitus, hypertension, and prehypertension than those with baPWV less than 1,400 cm/s (n = 223). In the multivariate analysis, mild (odds ratio (OR) = 2.58, 95% confidence interval (CI) = 1.02-6.54) and moderate (OR = 3.75, 95% CI = 1.02-13.81) CKD were positively associated with greater baPWV (≥1,400 cm/s). Age, prediabetes mellitus, diabetes mellitus, prehypertension, and hypertension were also independently associated with greater baPWV. In the multiple linear analysis, moderate (β = 120.45, P < .001) and mild CKD (β = 69.90, P = .01) were positively associated with baPWV. There was also an independently inverse correlation between eGFR and baPWV (β = -0.69, P = .04). Mild and moderate CKD increased the risk of greater arterial stiffness in elderly adults. Age, prediabetes mellitus, diabetes mellitus, prehypertension, and hypertension were also important correlates of increased arterial stiffness.

Theoretical studies of elastic properties of orthorhombic LiBH4

We have presented a study of the elastic properties of orthorhombic Pnma structural LiBH4 by first-principles calculations using a projected augmented plane-wave method. The single crystal elastic constants are successfully obtained from the stress–strain relationship calculations and the strain energy–strain curves calculations, respectively. The Shear and Young‘s moduli as well as Poisson‘s ratio for ideal polycrystalline LiBH4 are calculated. The bulk moduli are in good agreement with recent experimental and theoretical results. The linear compressibility and the directional dependent Young‘s modulus are also calculated. The shear anisotropic factors and the elastic anisotropy of Pnma LiBH4 are analyzed. The Debye temperature and the average elastic wave velocity are derived from theoretical elastic constants. According to the obtained results, the Pnma LiBH4 is found to be mechanically stable and ductile at zero temperature and zero pressure.

Ultrasonic Properties of Hexagonal Closed Packed Metals

This work is focused on three types of ultrasonic velocities (V1, V2 and V3) in Mg and Cd hcp metals. These are determined using the SOEC and TOEC at room temperature. Ultrasonic waves were supposed to be propagated along different directions with the crystal axis (z-axis). Finally ultrasonic attenuation in Mg and Cd are evaluated at room temperature utilizing the SOEC and TOEC of the materials. Average wave velocity is highest at θ=55° along z-axis in these materials. The contributions of the elastic constants, thermal conductivity, thermal energy density, ultrasonic velocity and acoustic coupling constant to the total attenuation are studied.