期刊文献+
共找到20篇文章
< 1 >
每页显示 20 50 100
Effect of Fluid Electrical Property Changes on Surface Transverse Wave Sensors
1
作者 Chao Zhang Wenyan Wang +2 位作者 Yonggui Dong Yan Liu Guanping Feng 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2006年第A03期514-518,共5页
A fluid sensor based on the surface transverse wave (STW) delay line on ST-cut quartz has been developed and tested in a large number of fluids with different viscosity and permittivity levels.Influence of fluid mech... A fluid sensor based on the surface transverse wave (STW) delay line on ST-cut quartz has been developed and tested in a large number of fluids with different viscosity and permittivity levels.Influence of fluid mechanical and electrical properties on the sensor's response has been determined and the sensor's performance has been compared with a bulk acoustic wave (BAW) viscosity sensor.The result shows that the viscosity sensitivity of the developed STW sensor represented by the signal to noise ratio is lower than that of a 5 MHz BAW sensor.Applications of the sensor in detecting the quality of industrial fluids are discussed. 展开更多
关键词 surface transverse wave surface acoustic wave fluid sensor electrical property
下载PDF
THE ESTIMATE AND MEASUREMENT OF TRANSVERSE WAVE INTENSITY
2
作者 Ming Ruisen, Department of Architecture, Zhejiang University, Hangzhou 310027, China 《Acta Mechanica Solida Sinica》 SCIE EI 1997年第3期235-245,共11页
Transverse waves are a type of structural waves and should be considered in the analysis of high frequency vibration because the energy carried by transverse waves increases with the increase of frequency and becomes ... Transverse waves are a type of structural waves and should be considered in the analysis of high frequency vibration because the energy carried by transverse waves increases with the increase of frequency and becomes important at high frequencies. This paper studies the estimate theory and measuring technique of the transverse wave intensity in two-dimensional homogeneous structures. In general, the intensity vector is the sum of the effective intensity vector and the intensity variation vector. Each axial intensity component is proportional to two imaginary parts of cross spectral densities and its estimate is complicated. For the special case where transverse waves propagate in one direction, the intensity variation is zero and the estimate of the intensity is simplified. The intensity technique is formed based on the finite difference principle. Transverse wave intensity can be measured using a pair of two-transducer arrays lying in the orthogonal direction for the general case or a two-transducer array lying in the propagating direction for the special case. In order to assess the measurement accuracy of transverse wave intensify, the coupling loss factors from bending to transverse waves in building structures were measured using the intensity technique and compared with the results predicted and measured using the conventional method. It is shown that the agreement between the results measured using the intensity technique and that by the conventional method is good. 展开更多
关键词 transverse wave intensity estimate theory measurement accuracy
下载PDF
A New Guide Wave Inspection System Using Three Polarized Transverse Wave EMATs without Any Couplant
3
作者 Riichi Murayama 《Journal of Sensor Technology》 2016年第4期110-121,共12页
A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to ... A guide wave is provided with the characteristic of long range propagation in the axis direction of a pipe, so it is possible to detect many defects over a large pipe area at once. At present, there is a technique to generate a guide wave using a piezoelectric element (PZT). However, the transverse wave-transducer using PZT needs to require a high viscosity couplant because the transverse wave cannot travel into typical liquid like water or oil. A guide wave inspection system that uses an electromagnetic ultrasonic transducer (EMAT) which does not require any couplant has then been developed to solve this trouble. First, a guide wave into a pipe, L, T and F-mode, can be transmitted and received by a polarized shear horizontal transverse wave propagating to the thickness direction when the vibration direction has been adjusted to the best direction. At next stage, the three EMATs for L, T and F-mode with different polarized vibration directions were piled up to improve the performance at the same position under the permanent magnet to inspect the pipe at the same condition. Next, the system with the EMATs can be confirmed to be able to detect three guide wave modes signal with enough intensity. Finally, the detection performance using the test pipes with any artificial defects has been done by the developed pipe inspection system, and any drilled holes and any notches can be detected. It is indicated that the developed system could be useful in real industrial field. 展开更多
关键词 Guide wave transverse wave EMAT Nondestructive Inspection Pipe
下载PDF
The Magnetic Longitudinal (P-) Wave’s Propagation and Energy Models Underlying the Mechanisms of Its Capacity to Absorb Free Energy
4
作者 Jianzhong Jiang Yufeng Wang 《Journal of Power and Energy Engineering》 2024年第7期39-62,共24页
The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagn... The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagnetic (LEM) waves. The revised Maxwell’s equations include the crucial parameters being the attenuation time constants of magnetic vortex potential and electric vortex potential generated by external electromagnetic field within the propagation medium. Specific expressions for them are obtained through theoretical analysis. Subsequently, a model for propagating magnetic P-wave generated by the superposition of a left-handed photo and a right-handed photon in a vacuum is formulated based on reevaluated total current law and revised Faraday’s law, covering wave equations, energy equation, as well as propagation mode involving mutual induction and conversion between scalar magnetic field and vortex electric field. Furthermore, through theoretical derivations centered around magnetic P-wave, evidence was presented regarding its ability to absorb huge free energy through the entangled interaction between zero-point vacuum energy field and the torsion field produced by the vortex electric field. 展开更多
关键词 QED (Quantum Electrodynamics) Energy wave and TEM (transverse Electromagnetic) wave Magnetic P-wave Modified Faraday’s Law of Electromagnetic Induction Electric/Magnetic Vortex Potential Zero-Point Vacuum Energy
下载PDF
A 2.5-dimensional Analytical Model of Cold Leveling for Plates with Transverse Wave Defects 被引量:5
5
作者 Wei-hua CHEN Juan LIU +2 位作者 Zhen-shan CUI Ying-jie WANG Ying-rui WANG 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2015年第8期664-671,共8页
Waves occurring in cold-rolled plates or sheets can be divided into longitudinal and transverse waves. Classical leveling theories merely solve the problem of longitudinal waves, while no well accepted method can be e... Waves occurring in cold-rolled plates or sheets can be divided into longitudinal and transverse waves. Classical leveling theories merely solve the problem of longitudinal waves, while no well accepted method can be employed for transverse waves. In order to investigate the essential deformation law of leveling for plates with transverse waves, a 2.5-dimensional (2.5- D) analytical approach was proposed. In this model, the plate was transversely divided into some strips with equal width; the strips are considered to be in the state of plane strain and each group of adjacent strips are assumed to be deformation compatible under stress. After calculation, the bending deformation of each strip and the leveling effect of overall plate were obtained by comprehensNe consideration of various strips along with the width. Bending of roller is a main approach to eliminate the transverse waves, which is widely accepted by the industry, but the essential effect of bending of roller on the deformation of plates and the calculation of bending of roller are unknown. According to the 2.5-D analytical model, it can be found that, for plates, it is neutral plane offsetting and middle plane elongation or contraction under inner stress that can effectively improve plate shape. Taking double side waves as an example, the appropriate values of bending of roller were obtained by the 2.5-D analytical model related to different initial unevenness, which was applicable to the current on-line adjusting of bending of roller in rolling industry. 展开更多
关键词 plate leveling 2.5-dimensional analytical model transverse wave middle plane deformation
原文传递
The criterion of the existence or inexistence of transverse shock wave at wedge supported oblique detonation wave 被引量:7
6
作者 Ai-Feng Wang Wei Zhao Zong-Lin Jiang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2011年第5期611-619,共9页
A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave.After solution validation... A simplified theoretic method and numerical simulations were carried out to investigate the characterization of propagation of transverse shock wave at wedge supported oblique detonation wave.After solution validation,a criterion which is associated with the ratio Φ (u 2 /u CJ) of existence or inexistence of the transverse shock wave at the region of the primary triple was deduced systematically by 38 cases.It is observed that for abrupt oblique shock wave (OSW)/oblique detonation wave (ODW) transition,a transverse shock wave is generated at the region of the primary triple when Φ 〈 1,however,such a transverse shock wave does not take place for the smooth OSW/ODW transition when Φ 〉 1.The parameter Φ can be expressed as the Mach number behind the ODW front for stable CJ detonation.When 0.9 〈 Φ 〈 1.0,the reflected shock wave can pass across the contact discontinuity and interact with transverse waves which are originating from the ODW front.When 0.8 〈 Φ 〈 0.9,the reflected shock wave can not pass across the contact discontinuity and only reflects at the contact discontinuity.The condition (0.8 〈 Φ 〈 0.9) agrees well with the ratio (D ave /D CJ) in the critical detonation. 展开更多
关键词 Oblique detonation wave transverse shock wave Oblique shock wave Transition Numerical simulations
下载PDF
A novel type of transverse surface wave propagating in a layered structure consisting of a piezoelectric layer attached to an elastic half-space 被引量:2
7
作者 Zhenghua Qian Feng Jin Sohichi Hirose 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第3期417-423,共7页
The existence and propagation of transverse surface waves in piezoelectric coupled solids is investigated, in which perfect bonding between a metal/dielectric substrate and a piezoelectric layer of finite-thickness is... The existence and propagation of transverse surface waves in piezoelectric coupled solids is investigated, in which perfect bonding between a metal/dielectric substrate and a piezoelectric layer of finite-thickness is assumed. Dis- persion equations relating phase velocity to material con- stants for the existence of various modes are obtained in a simple mathematical form for a piezoelectric material of class 6mm. It is discovered and proved by numerical examples in this paper that a novel Bleustein-Gulyaev (B-G) type of transverse surface wave can exist in such piezoelectric cou- pled solid media when the bulk-shear-wave velocity in the substrate is less than that in the piezoelectric layer but greater than the corresponding B-G wave velocity in the same pie- zoelectric material with an electroded surface. Such a wave does not exist in such layered structures in the absence of pie- zoelectricity. The mode shapes for displacement and electric potential in the piezoelectric layer are obtained and discussed theoretically. The study extends the regime of transverse sur- face waves and may lead to potential applications to surface acoustic wave devices. 展开更多
关键词 transverse surface wave Piezoelectric coupled solids - Dispersion relationSurface acoustic wave devices
下载PDF
TRANSVERSE FORCES AND RESULTANT FORCES ON ARRAY OF BI-PILE IN IRREGULAR WAVES 被引量:1
8
作者 Yu Yuxiu and Zhang Ningchuan Professer, Civil Engi. Dept., Dalian University of Technology, Dalian Lecture, Civil Engi. Dept., Dalian Vniversity of Technology, Dalian 《China Ocean Engineering》 SCIE EI 1990年第1期29-41,共13页
The total transverse forces on each of the two piles in the side-by-side arrangement and tandem arrangement are experimentally investigated in irregular waves and the total in-line wave forces are measured simultaneou... The total transverse forces on each of the two piles in the side-by-side arrangement and tandem arrangement are experimentally investigated in irregular waves and the total in-line wave forces are measured simultaneously. The statistical and spectral characteristics of the transverse forces are analyzed. The ratio of the transverse force on each pile in group to that on a single pile is defined as the transverse groupling-pile factor, KGL. Both the transverse coefficients CLG and KGL for each pile in array are varied with the relative pile distance and KC number and their relationships are presented in this paper. Also the ratio of the resultant wave froce of in-line force and transverse force to the in-line force and the vriation of the resultant coefficient are investigated. 展开更多
关键词 transverse FORCES AND RESULTANT FORCES ON ARRAY OF BI-PILE IN IRREGULAR waveS BI
下载PDF
Exact transverse solitary and periodic wave solutions in a coupled nonlinear inductor-capacitor network
9
作者 Serge Bruno Yamgoué Guy Roger Deffo +1 位作者 Eric Tala-Tebue Francois Beceau Pelap 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第9期434-443,共10页
Through two methods, we investigate the solitary and periodic wave solutions of the differential equation describing a nonlinear coupled two-dimensional discrete electrical lattice. The fixed points of our model equat... Through two methods, we investigate the solitary and periodic wave solutions of the differential equation describing a nonlinear coupled two-dimensional discrete electrical lattice. The fixed points of our model equation are examined and the bifurcations of phase portraits of this equation for various values of the front wave velocity are presented. Using the sineGordon expansion method and classic integration, we obtain exact transverse solutions including breathers, bright solitons,and periodic solutions. 展开更多
关键词 nonlinear electrical lattices two-dimensional network sine-Gordon expansion exact transverse solitary wave solutions
下载PDF
Longitudinal Scalar Wave(LSW)Fact:It Is a True Science,Neither Pseudoscience Nor Fiction(A Short Memorandum)
10
作者 Bahman Zohuri Masoud J.Moghaddam 《Journal of Energy and Power Engineering》 2023年第2期57-62,共6页
The discovery of scalar energy many years ago has mostly been ignored since then.Scalar energy is still misunderstood,underappreciated,and underutilized today.To comprehend the future,one must look back at the past.Sc... The discovery of scalar energy many years ago has mostly been ignored since then.Scalar energy is still misunderstood,underappreciated,and underutilized today.To comprehend the future,one must look back at the past.Scalar energy was first discovered by Scottish physicist James Clark Maxwell,who was born in 1831.Maxwell made significant advances in mathematical physics.He developed the theories relating to electromagnetic fields and radiation.Maxwell’s discoveries were advanced by Nikola Tesla,who also created instruments that demonstrated the presence of scalar energy.Nicola Tesla discovered an electromagnetic longitudinal wave in the early 1900s.It is capable of lossless energy transmission over great distances,lossless power transmission through solid metal objects,and wireless energy transmission.In this patent,Tesla neither named it nor provided a description of how it operated.Now,in the twenty-first century,it is referred to as LSWs(longitudinal scalar waves).Instantaneous longitudinal waves called scalars cover the entire field.In contrast to electromagnetic waves,which are transverse and move along an axis in a certain direction,they do not propagate along an axis or have a direction.As“vector”waves,electromagnetic waves lose power as they travel farther and pass through solid metal objects.Scalar waves also offer a unique property that Tesla does not include in his patent,which concentrates on the transportation of energy.These waves can transmit information as well. 展开更多
关键词 QED(quantum electrodynamic) CED(classical electrodynamic) electromagnetic and classical electromagnetic energy wave and Hertzian wave TEM(transverse electromagnetic)wave
下载PDF
Temporal changes in shear wave splitting after the M=5. 2 Shimian Earthquake
11
作者 陈天长 李志君 +2 位作者 张润生 杜国光 彭万星 《Acta Seismologica Sinica(English Edition)》 CSCD 1995年第1期65-75,共11页
Just after the occurrence of an M=5. 2 earthquake in Shimian, Sichuan, two three-component seismometerswere set up near the epicenter of, the earthquake. Field observations were made for the four-year period from1989 ... Just after the occurrence of an M=5. 2 earthquake in Shimian, Sichuan, two three-component seismometerswere set up near the epicenter of, the earthquake. Field observations were made for the four-year period from1989 to 1992. Analysis of the data recorded from either aftershocks following the M=5. 2 earthquake or fromsmall earthquakes scattered in this region indicates the presence of shear wave splitting. And shear wave splittingvaries with ti-cue. The mean direction of polarization of the faster shear waves is N18°W during the pened of aftershock activity, which is consistent with the strike of the faulting plane of the mainshock; but has turned toN46'W from 1990 to 1992, which is consistent with the regional maximum compressive stress. The time delaysbetween split shear waves measured on records from 1990 to 1992 are about half of that in 1989. The results ohtamed from observations at two temporary stations are similar. This indicates that the temporal changes may berelated to the occurrence of the M= 5.2 mainshock. 展开更多
关键词 SICHUAN seismic wave transverse wave arrival time
下载PDF
Research on the Relationship between Shallow Shear Wave Velocity and Basement Structure in the Tianjin Coastal Area
12
作者 Gao Wuping Chen Yukun +3 位作者 Ren Feng Yan Chengguo Wang Zhisheng Yang Fei 《Earthquake Research in China》 2012年第4期512-519,共8页
Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. ... Shear wave velocity is one of the important dynamic characteristics of soil layers and applied widely in aseismic engineering. In this paper, 500 drill logging data are used to make a linear interpolation based on 0. 01° x 0. 01°x lm grid. A shallow 3-D shear wave velocity structure of Tianjin coastal area is obtained. According to the data and geological background, we selected two typical velocity profiles to try to introduce and explain its relationship to basement structure. The results show that the shear wave velocity structure clearly presents the characteristic of stratification and lateral inhomogeneity. Furthermore, the difference of the shear wave structure between tectonic elements is clear and the velocity structure between the two sides of the local or border fault in the Quaternary is disturbed or affected significantly. It intuitively shows that the basement structure and fault activity of this region had good control of sedimentation development and strata formation in the Quaternary period which would have an important effect on engineering seismic and geological condition evaluation. 展开更多
关键词 Shear wave velocity transverse wave well logging Tianjin coastal area Velocity structure Tectonic element Fault QUATERNARY
下载PDF
Study and Evaluation of Advanced TOFD Method for Inspection of Polyethylene Pipes but Welding
13
作者 Mohammad H. TAGHIPOUR 《Journal of Physical Science and Application》 2015年第5期349-355,共7页
Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly ... Polyethylene material has some specification that makes very difficult any kind of inspection based on ultrasonic. The acoustic impedance and sound velocity in this kind of material are near to the materials commonly used in ultrasonic wedges. Also this kind of materials are highly attenuative materials for ultrasound. To inspection of polyethylene circumferential but welds and overcome to all the problems mentioned, the especial technique of TOFD (Time of Flight Diffraction) method which employs low frequency probe and concentrate on the inspection area that longitudinal waves turn into transverse waves has been used. The purpose of inspection is determining the exact location of surface and internal welding defects. For this purpose, two separate polyethylene pipes with 10 inch in diameter, 15 mm thickness and also 25 inch diameter, 28 mm thickness, were selected. In total 40 artificial defects which involve 28 side drill holes in deferent depths and 12 surface and sub-surface notches were created. All artificially created defects were detected with very good accuracy. Unlike the conventional TOFD method which have 2 to 3 mm dead zone, by using the above method even surface notch with 0.5 mm has been detected. 展开更多
关键词 PE (Polyethylene pipe) ULTRASONIC transverse wave TOFD (Time of flight diffraction)
下载PDF
介质平板渐变波导中的横电波
14
作者 康寿万 《北方交通大学学报》 CSCD 北大核心 1993年第1期8-14,共7页
提出了一种研究渐变波导中场的分布的新方法,采用保角变换方法,把一个具有阶跃折射率的平板渐变波导,变换成一个厚度不变但折射率沿纵向为连续变化的平板波导.方便地求出波导中场的分布,再经过反变换,得到在渐变波导中的场.
关键词 平面光波导 渐变波导 横电波
下载PDF
The Acquisition Technique of High-resolution Seismic Data for the Prospecting of Active Faults
15
作者 Zhao Chengbin Liu Baojin Ji Jifa 《Earthquake Research in China》 2011年第3期320-329,共10页
The high-resolution shallow seismic technique can be used for more accurately prospecting the position and property of faults and for the preliminary study of fault activity.The author obtains many high quality stack ... The high-resolution shallow seismic technique can be used for more accurately prospecting the position and property of faults and for the preliminary study of fault activity.The author obtains many high quality stack time sections through the prospecting methods of different seismic sources,different group intervals and different observation systems on the Xiadian fault.These sections clearly display the stratum structure and the structure characteristics from several meters to several hundred meters of the Xiadian fault.The resolutions of the different seismic sources,different group intervals and different observing systems are obtained.The prospecting methods and work parameters applicable for goal stratum of different depths and different accuracy requirements are proposed through the analysis of the stack time sections.This lays a good foundation for raising the prospecting resolution of the fault position and the latest active time of the fault. 展开更多
关键词 Active fault HIGH-RESOLUTION Longitudinal wave and transverse wave Controlled seismic source Time section
下载PDF
Neutrino Temporal Oscillation
16
作者 Russell Bagdoo 《Journal of Modern Physics》 2021年第4期513-535,共23页
We conjecture the existence of massless neutrinos that are in the line of Standard Model (unable to account for the neutrino mass) but have characteristics that are not accounted for the Standard Model: they use a sho... We conjecture the existence of massless neutrinos that are in the line of Standard Model (unable to account for the neutrino mass) but have characteristics that are not accounted for the Standard Model: they use a shorter radial path than the photon and possess bosonic flavors, considered like bosons instead of fermions. We call this theory “neutrino temporal oscillation”. Faced with some experimental comparisons solar neutrinos, neutrinos from SN 1987A, cosmological neutrinos, the theory gives better results, explanations and sense than the complicated theory of neutrino oscillations (transformism). The deficit of detection of solar neutrinos would have been blindly attributed to the “neutrino oscillation” by physicists who quickly concluded that the neutrino and the photon follow the same transverse path. The “OPERA” experiment which measured the speed of neutrinos in 2011 resulted, after a “superluminal” saga, in neutrino speeds consistent with the speed of light, in data that the three existing types of neutrinos cannot explain, with the final outcome of a fourth “sterile” neutrino with non-standard interaction. OPERA findings aren’t just in conflict with existing theory, but other measurements as well. For example, a study from the Kamiokande II experiment in Japan of the supernova SN1987A found that light and neutrinos that departed this exploded star arrived at Earth within hours of each other. Even though measurements of the neutrinos emitted by this supernova strongly suggest that their speeds differ from light by less than one part in a billion, the fact remains that two types of data were collected, and that only one was retained to be consistent with the existing theory. Thus, the OPERA observation is in conflicts with the result of SN1987A, which itself is highly doubtful. And what about the neutrinos and antineutrinos born during the big bang, except that they were never detected and there is nothing to indicate that their speed could be other than that of light. Neutrino physics seems sick, belief is transformed into evidence. The theory of “Neutrino temporal oscillation” shows hint that massless neutrinos can take a shortcut through the three spatial dimensions of the space-time that we know. It represents within the Standard Model an open window on a “new physics” that has a connection with physical reality. 展开更多
关键词 Apparent Superluminal Neutrinos General Relativity Neutrino Oscillation Neutrino “Temporal” Oscillation “Bosonic” Flavors Radial Path (Longitudinal) transverse Path Longitudinal waves toc of the Neutrino transverse waves tc of the Photon False Flux of Neutrinos True Flux of Neutrinos
下载PDF
Propagation of elastic plane waves in homogeneous and transversely isotropic media 被引量:2
17
作者 WANG Xiaomin LI Mingxuan(Institute of Acoustics, Acadetnia Sinica Beijing 100080) 《Chinese Journal of Acoustics》 1998年第3期280-288,共9页
Solutions to the equation of waves motion are derived for homogeneous and transversely isotropic media such as fiber-reinforced composites, and three dimensional slowness surfaces are shown as well. A brief discussion... Solutions to the equation of waves motion are derived for homogeneous and transversely isotropic media such as fiber-reinforced composites, and three dimensional slowness surfaces are shown as well. A brief discussion on the propagation of plane waves is given.Elastic plane waves are characterized by slowness vectors, wave vectors, polarization vectors and group velocity vectors, etc. The results obtained are presented in a coordinate-free form due to the introduction of the crystal axis' orieniation vector which specifies the anisotropy of the media. Therefore, the results are the most general and convenient for further application 展开更多
关键词 GENE Propagation of elastic plane waves in homogeneous and transversely isotropic media ROSE
原文传递
Low frequency ultrasonic multi-mode Lamb wave method for characterizing the ultra-thin transversely isotropic laminate composite: Theory and experiment 被引量:1
18
作者 ZHANG Rui, WAN Mingxi, CHEN Xiao, (Department of Biomedical Engineering Xi’an Jiaotong University Xi’an 710049) CAO Wenwu is with the Intercollege Materials Research Laboratory The Pennsylvania State University University Park, PA, 16802, USA 《Chinese Journal of Acoustics》 2001年第4期355-364,共10页
A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The &... A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The 'ultra-thin' here means that the thickness of the plate is much less than the wavelength of the ultrasonic wave so that the echoes from the front and back faces of the plate can't be separated in the time domain. The dispersion equations for the low frequency ultrasonic Lamb waves with the propagation directions parallel and vertical to the fiber direction are derived. In conjunction with the least square algorithm method, the secant algorithm is used to estimate the parameters of the ultra-thin fiber-reinforced composite layer. The evaluation errors and the sensitivity of the method to different paramters of the thin composite are analyzed. The technique has been used to characterize the ultra-thin grass fiber reinforced PES composite with thickness down to ten percents of the ultrasonic wavelength. It is observed that the agreement between the nominal and the estimation values is reasonably good. 展开更多
关键词 wave mode Theory and experiment Low frequency ultrasonic multi-mode Lamb wave method for characterizing the ultra-thin transversely isotropic laminate composite
原文传递
Scattering of steady cross-plane shear waves by surfaces of arbitrary shape in homogeneous and transversely isotropic media
19
作者 WANG Xiaomin LI Mingxuan(Institute of Acoustics, Academia Sinica Beijing 100080) 《Chinese Journal of Acoustics》 1998年第4期307-317,共11页
Two-dimensional scalar equation for the displacement of steady cross-plane shear (SH) waves in homogeneous and transversely isotropic media like unidirectional fibrous com-posites is given. Then, thrbugh a simple coor... Two-dimensional scalar equation for the displacement of steady cross-plane shear (SH) waves in homogeneous and transversely isotropic media like unidirectional fibrous com-posites is given. Then, thrbugh a simple coordinate system transform, the scalar equation is standardized into a Helmholtz equation. Corresponding integral equations are derived for the scattering problems and boundary element method (BEM) is used to calculate the scattered fields of arbitrarily shaped obstacles with both soft and rigid boudary conditions numerically.A discussion is given on the numerical results which is mainly focused on the influence of the a-nisotropy of the media to the directivity of the scattered fields by circular cylindrical voids. 展开更多
关键词 Scattering of steady cross-plane shear waves by surfaces of arbitrary shape in homogeneous and transversely isotropic media
原文传递
Numerical investigation on detonation cell evolution in a channel with area-changing cross section 被引量:1
20
作者 DENG Bo HU ZongMin +1 位作者 TENG HongHui JIANG ZongLin 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2007年第6期797-808,共12页
The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Eff... The two-dimensional cellular detonation propagating in a channel with area-changing cross section was numerically simulated with the dispersion-controlled dissipative scheme and a detailed chemical reaction model. Effects of the flow ex-pansion and compression on the cellular detonation cell were investigated to illus-trate the mechanism of the transverse wave development and the cellular detona-tion cell evolution. By examining gas composition variations behind the leading shock,the chemical reaction rate,the reaction zone length,and thermodynamic parameters,two kinds of the abnormal detonation waves were identified. To explore their development mechanism,chemical reactions,reflected shocks and rarefac-tion waves were discussed,which interact with each other and affect the cellular detonation in different ways. 展开更多
关键词 detonation cells transverse waves detailed chemical reaction model numerical simulation
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部