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冲击波 4

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Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿（英文）》 2014年第8卷第1期页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要： The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词： horizontal stress index shear wave velocity flat dilatometer test cone penetration test

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definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wavevelocity and albuminuria: a prospective cohort study

《医学前沿（英文）》 2022年第16卷第5期页码 714-722 doi: 10.1007/s11684-021-0888-8

摘要： A new definition of metabolic dysfunction-associated fatty liver disease (MAFLD) has recently been proposed. We aim to examine the associations of MAFLD, particularly its discordance from non-alcoholic fatty liver disease (NAFLD), with the progression of elevated brachial-ankle pulse wave velocity (baPWV) and albuminuria in a community-based study sample in Shanghai, China. After 4.3 years of follow-up, 778 participants developed elevated baPWV and 499 developed albuminuria. In comparison with the non-MAFLD group, the multivariable adjusted odds ratio (OR) of MAFLD group for new-onset elevated baPWV was 1.25 (95% confidence interval (CI) 1.01–1.55) and 1.35 (95% CI 1.07–1.70) for albuminuria. Participants without NAFLD but diagnosed according to MAFLD definition were associated with higher risk of incident albuminuria (OR 1.77; 95% CI 1.07–2.94). Patients with MAFLD with high value of hepamet fibrosis score or poor-controlled diabetes had higher risk of elevated baPWV or albuminuria. In conclusion, MAFLD was associated with new-onset elevated baPWV and albuminuria independently of body mass index, waist circumference, and hip circumference. Individuals without NAFLD but diagnosed as MAFLD had high risk of albuminuria, supporting that MAFLD criteria would be practical for the evaluation of long-term risk of subclinical atherosclerosis among fatty liver patients.

关键词： metabolic dysfunction-associated fatty liver disease non-alcoholic fatty liver disease fibrosis score brachial-ankle pulse wave velocity albuminuria

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Accounting for the uncertainties in the estimation of average shear wave velocity using – correlations

《结构与土木工程前沿（英文）》 2021年第15卷第5期页码 1199-1208 doi: 10.1007/s11709-021-0749-1

摘要： Site-specific seismic hazard analysis is crucial for designing earthquake resistance structures, particularly in seismically active regions. Shear wave velocity ( V _S) is a key parameter in such analysis, although the economy and other factors restrict its direct field measurement in many cases. Various V _S–SPT– N correlations are routinely incorporated in seismic hazard analysis to estimate the value of V _S. However, many uncertainties question the reliability of these estimated V _S values. This paper comes up with a statistical approach to take care of such uncertainties involved in V _S calculations. The measured SPT– N values from all the critical boreholes were converted into statistical parameters and passed through various correlations to estimate V _S at different depths. The effect of different soil layers in the boreholes on the Vs estimation was also taken into account. Further, the average shear wave velocity of the top 30 m soil cover ( V _S30) is estimated after accounting for various epistemic and aleatoric uncertainties. The scattering nature of the V _S values estimated using different V _S– N correlations was reduced significantly with the application of the methodology. Study results further clearly demonstrated the potential of the approach to eliminate various uncertainties involved in the estimation of V _S30 using general and soil-specific correlations.

关键词： uncertainties V _S– N correlations V _S30 SPT data statistical methodology

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A simple method for evaluating liquefaction potential from shear wave velocity

Lianyang ZHANG,

《结构与土木工程前沿（英文）》 2010年第4卷第2期页码 178-195 doi: 10.1007/s11709-010-0023-4

摘要： The simplified procedure using shear wave velocity measurements is increasingly used to evaluate the seismic liquefaction potential of soils. This procedure is based on finding the boundary separating the liquefaction and non-liquefaction cases through the analysis of liquefaction case histories, following the general format of the Seed-Idriss simplified procedure based on standard penetration test (SPT) data. It is noted that many assumptions have been made in the simplified procedure. This paper develops a simple method for evaluating the liquefaction potential of soils from shear wave velocity by using the optimum seeking method to directly analyze the liquefaction history data and quantify the influence of major factors affecting the liquefactions potential of soils. The factors considered are the earthquake magnitude, the vertical effective overburden stress, the shear wave velocity, the peak acceleration at the ground surface of the site, and the fines content of the soil. The most important factor has been identified as the shear wave velocity. The developed method uses the measured data directly and in a very simple way. Neither stress-correction of shear wave velocity nor calculation of cyclic shear stress as in the simplified procedure is required. Comparisons indicate that the developed simple method has a higher success rate for evaluating liquefaction potential of soils than the simplified procedure. A case study is presented to illustrate the application of the developed simple method and further confirms its accuracy.

关键词： liquefaction earthquake simple method shear wave velocity case history introduction

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Experimental study on wire breakage detection by acoustic emission

Limin SUN, Ji QIAN

《结构与土木工程前沿（英文）》 2011年第5卷第4期页码 503-509 doi: 10.1007/s11709-011-0132-8

摘要： This paper experimentally investigated wire breakage detection in a steel cable by acoustic emission (AE) waveform. In the experiments, the attenuation laws of waveform amplitudes were discussed based on stress wave propagation in the wire, which was generated by kNocking and wire breakage. Then the wave velocity was calculated based on the reach time of the stress wave from each sensor. Finally, based on the waveform attenuation laws and the linear position method, the amplitude and energy of the source were confirmed through the measured waveform to identify the source category. The experimental results illustrated that the stress wave from different sources has a different frequency spectrum, and the amplitude attenuation factor varied with the stress wave frequency; high frequency waves had a greater attenuation factor. Compared with the other source, the wire breakage source contained a much higher energy, and thus, the wire breakage signal can be distinguished from the other source by comparing the non-attenuation energy at the source position.

关键词： acoustic emission (AE) waveform wire breakage attenuation factor wave velocity

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Influence of site conditions on seismic design parameters for foundations as determined via nonlinear site response analysis

Muhammad Tariq A. CHAUDHARY

《结构与土木工程前沿（英文）》 2021年第15卷第1期页码 275-303 doi: 10.1007/s11709-021-0685-0

摘要： Site conditions, including geotechnical properties and the geological setting, influence the near-surface response of strata subjected to seismic excitation. The geotechnical parameters required for the design of foundations include mass density ( ), damping ratio ( ), shear wave velocity ( ), and soil shear modulus ( ). The values of the last three parameters are sensitive to the level of nonlinear strain induced in the strata due to seismic ground motion. In this study, the effect of variations in soil properties, such as plasticity index ( ), effective stress ( ), over consolidation ratio (OCR), impedance contrast ratio ( ) between the bedrock and the overlying strata, and depth of soil strata over bedrock ( ), on seismic design parameters ( , , and ) was investigated for National Earthquake Hazards Reduction Program (NEHRP) site classes C and D, through 1D nonlinear seismic site response analysis. The Morris one-at-a-time (OAT) sensitivity analysis indicated that , , and were significantly influenced by variations in , while affected more than it affected and . However, the influence of on these parameters was less significant. It was also found that variations in soil properties influenced seismic design parameters in soil type D more significantly than in soil type C. Predictive relationships for , , and were derived based on the 1D seismic site response analysis and sensitivity analysis results. The , , and values obtained from the analysis were compared with the corresponding values in NEHRP to determine the similarities and differences between the two sets of values. The need to incorporate and in the metrics for determining , , and for the seismic design of foundations was highlighted.

关键词： site effects 1D seismic site response analysis sensitivity analysis foundations shear wave velocity soil shear modulus

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物理光学的若干进展

黄志洵

《中国工程科学》 2006年第8卷第2期页码 18-29

摘要：

就物理光学方面的一系列理论和实验研究，如Goos-Hänchen位移、FTIR现象、负折射率、太赫超光速实验、光子静质量测量等做了评述和讨论。指出近年来的研究显示了消失波现象的重要性，例如消失波可造成超光速传播，且常有新方法和新测量结果；介绍了物理光学在相关领域的技术创新和应用实例；讨论了光子有静止质量的可能性及光频标准和光频测量的历史和新的进展。

关键词：物理光学负波速负折射率 GH位移消失波光子静质量

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复杂结构中异常区域对波速成像影响的量化研究 Article

董陇军, 童小洁, 马举

《工程（英文）》 2021年第7卷第7期页码 1011-1022 doi: 10.1016/j.eng.2020.06.021

摘要：

复杂结构中异常区域的探测是地下空间开发急需解决的技术瓶颈。人工开挖和天然因素导致的地质结构变化大大降低了传统勘探方法的效率。随着实时监测技术的出现，波速场精确成像使异常区域精准探测成为可能。但成像结果易受到多种因素的影响，尤其在小尺度上应用时。为此，我们采用被动声发射监测和主动超声波探测相结合的增强型三维成像技术，对包括初始速度模型、传感器排布、路径覆盖范围、事件的空间分布和定位误差等因素进行研究，共开展相关测试37组，获得了不同因素对成像精度的量化影响。测试结果表明该成像技术可有效应对复杂结构中的异常区域的精准探测，且在初始迭代参数优化后，异常区域的探测精度显著提高。

关键词：异常区域探测成像作用波速路径

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柱形地形上单浮体的辐射和散射问题

吴必军,郑永红,游亚戈,孙晓燕,陈勇

《中国工程科学》 2004年第6卷第2期页码 48-55

摘要：

在有限水深、同轴但半径大于或等于浮体半径的圆柱体障碍物地形条件下，基于特征函数展开法，推导了垂直放置的圆柱形浮体由于波的辐射和散射作用所表现的动力学和运动学特征表达式，涉及浮体做垂荡、横荡和横摇运动所产生的辐射势，以及在入射波的作用下，由于浮体固定不动而产生的散射势，并推导了激励力、附加质量和阻尼系数表达式。采用与同轴、同半径圆柱体障碍物地形上单浮体水动力学特性相比的方式和激励力计算两种方法验证了推导的表达式，最后分析了障碍物几何尺寸对浮体水动力学特性的特有影响。

关键词：解析方法速度势波浪力

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超光速问题与电磁波异常传播

黄志洵

《中国工程科学》 2000年第2卷第10期页码 80-92

摘要：

讨论了超光速研究的历史背景和在狭义相对论框架内进行工作的可能性；指出已有的实验（用单光子、激光脉冲和微波）在量子隧穿过程中呈现出的超光速行为，是在特定物理条件下才有的。认为经典电报员方程与Klein-Gordon方程的相似，使得前者可用于粒子隧穿和超光速现象的研究。讨论了不久前发表的王力军博士的超光速实验，展望了超光速研究的未来。

关键词：超光速微波异常传播快子量子隧道过程消失模负群速

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High velocity impact of metal sphere on thin metallic plate using smooth particle hydrodynamics (SPH)

Hossein ASADI KALAMEH, Arash KARAMALI, Cosmin ANITESCU, Timon RABCZUK

《结构与土木工程前沿（英文）》 2012年第6卷第2期页码 101-110 doi: 10.1007/s11709-012-0160-z

摘要： The modeling of high velocity impact is an important topic in impact engineering. Due to various constraints, experimental data are extremely limited. Therefore, detailed numerical simulation can be considered as a desirable alternative. However, the physical processes involved in the impact are very sophisticated; hence a practical and complete reproduction of the phenomena involves complicated numerical models. In this paper, we present a smoothed particle hydrodynamics (SPH) method to model two-dimensional impact of metal sphere on thin metallic plate. The simulations are applied to different materials (Aluminum, Lead and Steel); however the target and projectile are formed of similar metals. A wide range of velocities (300, 1000, 2000, and 3100 m/s) are considered in this study. The goal is to study the most sensitive input parameters (impact velocity and plate thickness) on the longitudinal extension of the projectile, penetration depth and damage crater.

关键词： smoothed particle hydrodynamics high velocity impact sensitivity analysis

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Experimental study on velocity characteristics of recirculation zone in humid air non-premixed flame

GU Xin, ZANG Shusheng, GE Bing

《能源前沿（英文）》 2008年第2卷第2期页码 140-144 doi: 10.1007/s11708-008-0037-y

摘要： To examine the effect of the flow field within the recirculation zone on flame structure, the characteristic velocity fields of methane/humid air flame in non-premixed combustion behind a disc bluff-body burner were experimentally studied by particle image velocimeter (PIV).The results show that two stagnation points exist on the centerline in the recirculation zone flame. However, the distance of the two stagnation points in humid air combustion shortens, and the minimal dimensionless velocity increases compared with the conventional non-humid air combustion. In addition, the positional curves of the minimal velocities can be partitioned into three phases representing three different flame patterns. The analysis of axial minimal velocities on the centerline and their positions under different co-flow air velocity conditions reveals that fuel-to-air velocity ratio is the crucial parameter that governs humid air combustion flame characteristics.

关键词： distance bluff-body fuel-to-air velocity stagnation parameter

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Study on wave rotor refrigerators

Yuqiang DAI, Dapeng HU, Meixia DING

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 83-87 doi: 10.1007/s11705-009-0075-y

摘要： As a novel generation of a rotational gas wave machine, the wave rotor refrigerator (WRR) is an unsteady flow device used for refrigeration, in whose passages pressured streams directly contact and exchange energy due to the movement of pressure waves. In this paper, the working mechanism and refrigeration principle are investigated based on the one-dimensional unsteady flow theory. A basic limitation on main structural parameters and operating parameters is deduced and the wave diagram of WRR to guide designing is sketched. The main influential factors are studied through an experiment. In the DUT Gas Wave Refrigeration Studying and Development Center (GWRSDC) lab, the isentropic efficiency can now reach about 65%. The results show that the WRR is a feasible and promising technology in pressured gas refrigeration cases.

关键词： wave rotor refrigeration unsteady flow theory wave diagram

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Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

《机械工程前沿（英文）》 2009年第4卷第3期页码 326-331 doi: 10.1007/s11465-009-0045-6

摘要： This study aims to model the propagation of Lamb waves used in structure health monitoring. A number of different numerical computational techniques have been developed for wave propagation studies. The local interaction simulation approach, used for modeling sharp interfaces and discontinuities in complex media (LISA/SIM theory), has been effectively applied to numerical simulations of elastic wave interaction. This modeling is based on the local interaction simulation approach theory and is finally accomplished through the finite elements software Ansys11. In this paper, the Lamb waves propagating characteristics and the LISA/SIM theory are introduced. The finite difference equations describing wave propagation used in the LISA/SIM theory are obtained. Then, an anisotropic metallic plate model is modeled and a simulating Lamb waves signal is loaded on. Finally, the Lamb waves propagation modeling is implemented.

关键词： Lamb wave modeling LISA/SIM theory finite difference equation finite element

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Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internal

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1349-1358 doi: 10.1007/s11709-020-0650-3

摘要： A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact. Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived. For this purpose, layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact. Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure. In case of experiencing any in-plane failure mode, the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics. Namely, mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model. In the event of delamination occurrence, the solution is terminated. The obtained results are validated with available experimental observations in open literature. It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.

关键词： composite pressure vessel low-velocity impact failure theoretical solution progressive damage modeling

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标题作者时间类型操作

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

definition of metabolic dysfunction-associated fatty liver disease with elevated brachial-ankle pulse wavevelocity and albuminuria: a prospective cohort study

期刊论文

Accounting for the uncertainties in the estimation of average shear wave velocity using – correlations

期刊论文

A simple method for evaluating liquefaction potential from shear wave velocity

Lianyang ZHANG,

期刊论文

Experimental study on wire breakage detection by acoustic emission

Limin SUN, Ji QIAN

期刊论文

Influence of site conditions on seismic design parameters for foundations as determined via nonlinear site response analysis

Muhammad Tariq A. CHAUDHARY

期刊论文