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Academic literature on the topic 'Transmission and reflection coefficients'

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Published: 30 May 2022
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Journal articles on the topic "Transmission and reflection coefficients"

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Yang, Chun, Yun Wang, and Yanghua Wang. "Reflection and transmission coefficients of a thin bed." GEOPHYSICS 81, no. 5 (September 2016): N31—N39. http://dx.doi.org/10.1190/geo2015-0360.1.

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The study of thin-bed seismic response is an important part in lithologic and methane reservoir modeling, critical for predicting their physical attributes and/or elastic parameters. The complex propagator matrix for the exact reflections and transmissions of thin beds limits their application in thin-bed inversion. Therefore, approximation formulas with a high accuracy and a relatively simple form are needed for thin-bed seismic analysis and inversion. We have derived thin-bed reflection and transmission coefficients, defined in terms of displacements, and approximated them to be in a quasi-Zoeppritz matrix form under the assumption that the middle layer has a very thin thickness. We have verified the approximation accuracy through numerical calculation and concluded that the errors in PP-wave reflection coefficients [Formula: see text] are generally smaller than 10% when the thin-bed thicknesses are smaller than one-eighth of the PP-wavelength. The PS-wave reflection coefficients [Formula: see text] have lower approximation accuracy than [Formula: see text] for the same ratios of thicknesses to their respective wavelengths, and the [Formula: see text] approximation is not acceptable for incident angles approaching the critical angles (when they exist) except in the case of extremely strong impedance difference. Errors in phase for the [Formula: see text] and [Formula: see text] approximation are less than 10% for the cases of thicknesses less than one-tenth of the wavelengths. As expected, a thinner middle layer and a weaker impedance difference would result in higher approximation accuracy.
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Nardone, P., J. Fortuny, and A. Sieber. "Initial conditions, reflection and transmission coefficients revisited." Journal of Electromagnetic Waves and Applications 10, no. 11 (January 1996): 1527–41. http://dx.doi.org/10.1163/156939396x00900.

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Simon, María C., and Liliana I. Perez. "Reflection and Transmission Coefficients in Uniaxial Crystals." Journal of Modern Optics 38, no. 3 (March 1991): 503–18. http://dx.doi.org/10.1080/09500349114552751.

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Imhof, Matthias G. "Scale dependence of reflection and transmission coefficients." GEOPHYSICS 68, no. 1 (January 2003): 322–36. http://dx.doi.org/10.1190/1.1543218.

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Well logs show that heterogeneities occur at many different depth scales. This study examines the effects of these heterogeneities on the propagation of seismic waves, and specifically the dependence of reflection and transmission on the spatial scale content of the medium. Wavelet transformations are used to filter certain spatial scales from an acoustic sonic log. The scale‐filtered logs are used to construct layerstack models for which reflection and transmission seismograms are computed. The modified logs are also used to calculate frequency dependent reflection and transmission coefficients as functions of scale content. It is observed that features shorter than one‐fourth of the dominant wavelength have little effect on the reflection and transmission of seismic waves. Features larger than the dominant wavelength affect arrival times of individual packets within the wavetrain, but often these features hardly alter the overall appearance of individual wave packets. Reflection and transmission coda are primarily governed by heterogeneity at spatial scales similar to half the propagating wavelength. These scales appear to control the presence and shape of the events within the coda. The study also shows that the arrival times of packets at 1 kHz approach the theoretically expected value obtained from the harmonic velocity average, and the arrival times of packets below 1 Hz approach the theoretical value expected for the Backus average of the velocities.
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Robinson, Enders A. "Seismic time‐invariant convolutional model." GEOPHYSICS 50, no. 12 (December 1985): 2742–51. http://dx.doi.org/10.1190/1.1441894.

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A layered‐earth seismic model is subdivided into two subsystems. The upper subsystem can have any sequence of reflection coefficients but the lower subsystem has a sequence of reflection coefficients which are small in magnitude and have the characteristics of random white noise. It is shown that if an arbitrary wavelet is the input to the lower lithologic section, the same wavelet convolved with the white sequence of reflection coefficients will be the reflected output. That is, a white sedimentary system passes a wavelet in reflection as a linear time‐invariant filter with impulse response given by the reflection coefficients. Thus, the small white lithologic section acts as an ideal reflecting window, producing perfect primary reflections with no multiple reflections and no transmission losses. The upper subsystem produces a minimum‐delay multiple‐reflection waveform. The seismic wavelet is the convolution of the source wavelet, the absorption effect, this multiple‐reflection waveform, and the instrument effect. Therefore, the seismic trace within the time gate corresponding to the lower subsystem is given by the convolution of the seismic wavelet with the white reflection coefficients of the lower subsystem. The linear time‐invariant seismic model used in predictive deconvolution has been derived. Furthermore, it is shown that any layered subsystem which has small reflection coefficients acts as a linear time‐invariant filter. This explains why time‐invariant deconvolution filters can be used within various time gates on a seismic trace which at first appearance might look like a continually time‐varying phenomenon.
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Norris, Andrew N. "Integral identities for reflection, transmission, and scattering coefficients." Journal of the Acoustical Society of America 144, no. 4 (October 2018): 2109–15. http://dx.doi.org/10.1121/1.5058681.

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Khaliullin, D. Y., and S. A. Tretyakov. "Reflection and transmission coefficients for thin bianisotropic layers." IEE Proceedings - Microwaves, Antennas and Propagation 145, no. 2 (1998): 163. http://dx.doi.org/10.1049/ip-map:19981452.

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Nechtschein, S., and F. Hron. "Effects of anelasticity on reflection and transmission coefficients." Geophysical Prospecting 45, no. 5 (September 1997): 775–93. http://dx.doi.org/10.1046/j.1365-2478.1997.590288.x.

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Yang, Chun, and Yun Wang. "Reflection and transmission coefficients of poroelastic thin-beds." Journal of Geophysics and Engineering 15, no. 5 (June 29, 2018): 2209–20. http://dx.doi.org/10.1088/1742-2140/aac359.

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Sabah, Cumali, and Savas Uckun. "Reflection and transmission coefficients of multiple chiral layers." Science in China Series E: Technological Sciences 49, no. 4 (August 2006): 457–67. http://dx.doi.org/10.1007/s11431-006-2010-5.

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Dissertations / Theses on the topic "Transmission and reflection coefficients"

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Borocin, F. "(Derivation of) reflection/transmission coefficients for fluid-saturated poroelastic sediments." Thesis, University of Edinburgh, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.641793.

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The interpretation of reflection, transmission and conversion (RTC) coefficients in fluid-saturated porous rock is of utmost importance for the characterisation of hydrocarbon reservoirs. It has also been suggested that high-pressure pore-fluid is responsible for anomalously high (up to 0.15-0.25) values of reflection coefficients (deep crustal reflectors) in the lower crust, subduction zones and subglacial deforming sediments. In my thesis I consider the interaction of seismic waves at the interface between fluid-saturated poroelastic media, taking properly into account the effects of fluid-solid interaction. I derive dynamic equations for wave propagation in poro-elastic media and obtain an explicit wave decomposition in up- and down-going components. I then develop an algorithm to compute RTC coefficients at the interface between two arbitrary poro-elastic media, when possible pore-pressure discontinuity at the interface is taken into account. My algorithm is written in a matrix form allowing me to compute RTC coefficients for plane waves at all frequencies and all angles of incidence. This algorithm encompasses both visco-elastic and poro-elastic cases including the effects caused by partially sealed interface. Using numerical examples I show that my algorithm is consistent with (visco-)elastic case. It is designed in a matrix form suitable for conventional computations of multilayered stacks as used in the reflectivity method. A range of possible applications and extensions such as wave propagation in finely-layered fluid-saturated sediments are discussed.
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Zhang, Bing. "Joint identification in structural waveguides using wave reflection and transmission coefficients." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/50563/.

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The dynamic modelling of one-dimensional jointed structures is relevant to many engineering applications, such as pipe systems and beam networks in constructions. Currently available techniques are undermined by inadequate ability to model the joints and other discontinuities due to uncertainty in their properties. Measured modal data can be used to update joint models, but often with limited success. In this thesis a wave approach is employed to investigate the reflection and transmission coefficients of various joint models in structural waveguides. The reflection and transmission coefficients are potentially more sensitive to the parameters of the joint models. Numerical simulations and experiments have been performed on three types of jointed waveguides. Appropriate models have been identified for these cases and sensitivities of the scattering coefficients to joint parameters have been investigated. Accurate measurement of the reflection and transmission coefficients is desired in order to estimate joint parameters. A noise model is developed and a perturbation method is used to study the influence of measurement noise on the estimated reflection and transmission coefficients. An iterative method is examined to solve the non-linear problem of estimating the parameters of a joint from measured reflection and transmission coefficients, in a leastsquares sense. Issues concerning the iteration process, such as the selection of objective functions and frequency ranges, are examined in accordance with the sensitivity of the objective function to unknown parameters. The parameter identification method is validated by numerical simulation case studies and then verified by using measured data for mass discontinuities on beams, a supported straight pipe and a right-angled pipe bend. The case studies demonstrate that parameter identification of discontinuities in waveguides by using the wave approach is a success where modal methods are inappropriate.
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Jeyakumaran, R. "Some scattering and sloshing problems in linear water wave theory." Thesis, Brunel University, 1993. http://bura.brunel.ac.uk/handle/2438/5390.

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Using the method of matched asymptotic expansions the reflection and transmission coefficients are calculated for scattering of oblique water waves by a vertical barrier. Here an assumption is made that the barrier is small compared to the wavelength and the depth of water. A number of sloshing problems are considered. The eigenfrequencies are calculated when a body is placed in a rectangular tank. Here the bodies considered are a vertical surface-piercing or bottom-mounted barrier, and circular and elliptic cylinders. When the body is a vertical barrier, the eigenfunction expansion method is applied. When the body is either a circular or elliptic cylinder, and the motion is two-dimensional, the boundary element method is applied to calculate the eigenfrequencies. For comparison, two approximations, "a wide-spacing", and "a small-body" are used for a vertical barrier and circular cylinder. In the wide-spacing approximation, the assumption is made that the wavelength is small compared with the distance between the body and walls. The small-body approximation means that a typical dimension of the body is much larger than the cross-sectional length scale of the fluid motion. For an elliptic cylinder, the method of matched asymptotic expansions is used and compared with the result of the boundary- element method. Also a higher-order solution is obtained using the method of matched asymptotic expansions, and it is compared with the exact solution for a surface-piercing barrier. Again the assumption is made that the length scale of the motion is much larger than a typical body dimension. Finally, the drift force on multiple bodies is considered the ratio of horizontal drift force in the direction of wave advance on two cylinders to that on an isolated cylinder is calculated. The method of matched asymptotic expansions is used under the assumption that the wavelength is much greater than the cylinder spacing.
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Stamos, Dimitrios Georgios. "Experimental Analysis of the Interaction of Water Waves With Flexible Structures." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/27567.

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An experimental investigation of the interaction of water waves with flexible structures acting as breakwaters was carried out. Wave profiles, mapped out by water level measuring transducers, were studied to provide information on the performance of different breakwater models. A new signal analysis procedure for determining reflection coefficients based on wavelet theory was developed and compared to a conventional method. The reliability of using wavelet analysis to separate a partial standing wave into incident and reflected wave components was verified with a numerical example. It was also verified by the small variance in the estimates of the incident wave height from independent experimental measurements. Different geometries of rigid and flexible structures were constructed and examined. Reflection, transmission and energy loss coefficients were obtained over them. The influence of various properties of the models, such as the width and the internal pressure, on the effectiveness in reflecting or absorbing the incident wave energy was determined. Various factors which affect the performance of the breakwater, including the water depth, the wave length and the wave amplitude, were measured and documented. Suspended and bottom-mounted models were considered. The flow field over and near a hemi-cylindrical breakwater model was also examined using a flow visualization technique. An overall comparison among the models has also been provided. The results showed that the rectangular models, rigid and flexible, are the most effective structures to dissipate wave energy. The flow visualization technique indicated that the flow conforms with the circular geometry of a hemi-cylindrical breakwater model, yielding no flow separation.
Ph. D.
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Walker, Jonathan Bearnarr. "An Empirical Method of Ascertaining the Null Points from a Dedicated Short-Range Communication (DSRC) Roadside Unit (RSU) at a Highway On/Off-Ramp." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/85151.

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The deployment of dedicated short-range communications (DSRC) roadside units (RSUs) allows a connected or automated vehicle to acquire information from the surrounding environment using vehicle-to-infrastructure (V2I) communication. However, wireless communication using DSRC has shown to exhibit null points, at repeatable distances. The null points are significant and there was unexpected loss in the wireless signal strength along the pathway of the V2I communication. If the wireless connection is poor or non-existent, the V2I safety application will not obtain sufficient data to perform the operation services. In other words, a poor wireless connection between a vehicle and infrastructure (e.g., RSU) could hamper the performance of a safety application. For example, a designer of a V2I safety application may require a minimum rate of data (or packet count) over 1,000 meters to effectively implement a Reduced Speed/Work Zone Warning (RSZW) application. The RSZW safety application is aimed to alert or warn drivers, in a Cooperative Adaptive Cruise Control (CACC) platoon, who are approaching a work zone. Therefore, the packet counts and/or signal strength threshold criterion must be determined by the developer of the V2I safety application. Thus, we selected an arbitrary criterion to develop an empirical method of ascertaining the null points from a DSRC RSU. The research motivation focuses on developing an empirical method of calculating the null points of a DSRC RSU for V2I communication at a highway on/off-ramp. The intent is to improve safety, mobility, and environmental applications since a map of the null points can be plotted against the distance between the DSRC RSU and a vehicle's onboard unit (OBU). The main research question asks: 'What is a more robust empirical method, compared to the horizontal and vertical laws of reflection formula, in determining the null points from a DSRC RSU on a highway on/off ramp?' The research objectives are as follows: 1. Explain where and why null points occur from a DSRC RSU (Chapter 2) 2. Apply the existing horizontal and vertical polarization model and discuss the limitations of the model in a real-world scenario for a DSRC RSU on a highway on/off ramp (Chapter 3 and Appendix A) 3. Introduce an extended horizontal and vertical polarization null point model using empirical data (Chapter 4) 4. Discuss the conclusion, limitations of work, and future research (Chapter 5). The simplest manner to understand where and why null points occur is depicted as two sinusoidal waves: direct and reflective waves (i.e., also known as a two-ray model). The null points for a DSRC RSU occurs because the direct and reflective waves produce a destructive interference (i.e., decrease in signal strength) when they collide. Moreover, the null points can be located using Pythagorean theorem for the direct and reflective waves. Two existing models were leveraged to analyze null points: 1) signal strength loss (i.e., a free space path loss model, or FSPL, in Appendix A) and 2) the existing horizontal and vertical polarization null points from a DSRC RSU. Using empirical data from two different field tests, the existing horizontal and vertical polarization null point model was shown to contain limitations in short distances from the DSRC RSU. Moreover, the existing horizontal and vertical polarization model for null points was extremely challenging to replicate with over 15 DSRC RSU data sets. After calculating the null point for several DSRC RSU heights, the paper noticed a limitation of the existing horizontal and vertical polarization null point model with over 15 DSRC RSU data sets (i.e., the model does not account for null points along the full length of the FSPL model). An extended horizontal and vertical polarization model is proposed that calculates the null point from a DSRC RSU. There are 18 model comparisons of the packet counts and signal strengths at various thresholds as perspective extended horizontal and vertical polarization models. This paper compares the predictive ability of 18 models and measures the fit. Finally, a predication graph is depicted with the neural network's probability profile for packet counts =1 when greater than or equal to 377. Likewise, a python script is provided of the extended horizontal and vertical polarization model in Appendix C. Consequently, the neural network model was applied to 10 different DSRC RSU data sets at 10 unique locations around a circular test track with packet counts ranging from 0 to 11. Neural network models were generated for 10 DSRC RSUs using three thresholds with an objective to compare the predictive ability of each model and measure the fit. Based on 30 models at 10 unique locations, the highest misclassification was 0.1248, while the lowest misclassification was 0.000. There were six RSUs mounted at 3.048 (or 10 feet) from the ground with a misclassification rate that ranged from 0.1248 to 0.0553. Out of 18 models, seven had a misclassification rate greater than 0.110, while the remaining misclassification rates were less than 0.0993. There were four RSUs mounted at 6.096 meters (or 20 feet) from the ground with a misclassification rate that ranged from 0.919 to 0.000. Out of 12 models, four had a misclassification rate greater than 0.0590, while the remaining misclassification rates were less than 0.0412. Finally, there are two major limitations in the research: 1) the most effective key parameter is packet counts, which often require expensive data acquisition equipment to obtain the information and 2) the categorical type (i.e., decision tree, logistic regression, and neural network) will vary based on the packet counts or signal strength threshold that is dictated by the threshold criterion. There are at least two future research areas that correspond to this body of work: 1) there is a need to leverage the extended horizontal and vertical polarization null point model on multiple DSRC RSUs along a highway on/off ramp, and 2) there is a need to apply and validate different electric and magnetic (or propagation) models.
Ph. D.
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Alexandre, Armando Emanuel Mocho fernandes e. "Wave energy converter strings for electricity generation and coastal protection." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/wave-energy-converter-strings-for-electricity-generation-and-coastal-protection(c7d53691-22f6-4ea8-a7ec-c9850218a1d5).html.

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Generation of electricity from ocean waves has seen increasing research and commercial interest in recent years. The development of projects of several hundred megawatts rated capacity is now being considered. There is a clear need for improved understanding of the environmental impact of large-scale wave energy extraction, particularly in nearshore regions where sediment transport and cliff erosion may be affected. This thesis investigates the change in nearshore wave conditions and sediment transport due to energy extraction by long strings of wave energy devices. The influence of wave energy converter (WEC) arrays has been studied using transmission coefficients implemented within a spectral wave model. It is shown that the breaking wave height nearshore is larger (5%) if transmission is defined as frequency dependent. This is due to the energy dissipation processes associated with different wave frequencies. Linear wave theory is employed to determine frequency dependent transmission and reflection coefficients across a line of wave energy devices based onthe amplitude of scattered and radiated waves. This approach is compared with experimental measurements of the wave field in the vicinity of an array of five heaving floats. The transmitted wave amplitude is predicted with reasonable accuracy but additional numerical damping is required to predict the measured float response amplitude. This comparison indicates that linear analysis is an acceptable approach for predicting float response and wave field in the vicinity of the array for a certain range of conditions. Linear wave analysis is subsequently applied to investigate the variation of transmission coefficients with distance inshore of a long array of heaving WECs undergoing free response and with damping specified to optimise power extraction. A method is presented for identifying representative transmission and reflection coefficients such that change in wave energy is equal to energy extraction by the devices. These coefficients are employed to quantify the change in nearshore conditions due to deployment of a long line of wave devices at a site near the East Anglian coastline. Wave conditions are modelled at 12 points along the shoreline over a 140 year period and significant wave height reductions up to 30% were obtained. Importantly, changes in nearshorewave direction are also observed. Analysis using the sediment transport model SCAPE (Soft Cliff and Platform Erosion model) indicates that the introduction of the array reduces both the sediment transport rate and cliff recession rate by an average of 50%.
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Boonserm, Petarpa. "Rigorous bounds on transmission, reflection, and Bogoliubov coefficients : a thesis submitted to the Victoria University of Wellington in fulfilment of the requirements for the degree of Doctor of Philosophy in Mathematics /." ResearchArchive@Victoria e-Thesis, 2009. http://hdl.handle.net/10063/942.

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Abdoulatuf, Antoisse. "Modélisation et simulation de la propagation d'ondes guidées dans des milieux élastiques en présence d'incertitudes : Application à la caractérisation ultrasonore." Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1011/document.

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Dans ce travail de thèse, nous nous sommes intéressés à la modélisation et la simulation de la propagation d'ondes ultrasonores dans l'os cortical. Plus précisément, nous avons étudié et analysé la technique dite des ultrasons quantitatifs (Quantitative Ultrasound, QUS) pour l'évaluation de la qualité du tissu osseux. Il s'agit d'une technique émergente dont l'application aux tissus osseux suscite un intérêt particulier dans la communauté scientifique. Le tissu osseux étant un tissu vivant, il est sujet au vieillissement et à divers pathologies parmi lesquelles on peut citer ostéoporose, ostéomalacie, ostéoporomalacie, ou encore, la maladie dite de Paget. Pour accompagner les soins à prodiguer au tissu osseux, une surveillance de sa qualité s'avère indispensable. Dans ce contexte, les méthodes ultrasonores sont réputées être intéressantes, de par leurs caractères non-invasif, peu coûteux, portable et non-ionisant. Cependant, utiliser des ultrasons dans le cadre de la caractérisation du tissu osseux, suppose une compréhension profonde des différents phénomènes physiques mis en jeu lors de leur propagation. Dans cette optique, notre travail est développé dans la thématique de la modélisation dédiée à la propagation des ondes ultrasonores dans des guides d'ondes multidimensionnels, hétérogènes, anisotropes, et composés de matériaux dont l'hétérogénéité peut être qualifiée d'aléatoire. Une des originalités de cette thèse concerne l'étude des coefficients de réflexion et de transmission et des courbes de dispersion en présence d'incertitudes dues aux propriétés matérielles. Dans une première partie, nous étudions les phénomènes de réflexion/transmission via un modèle tri-couches bidimensionnels prenant en compte les tissus mous et l'hétérogénéité aléatoire du tissu osseux. Nous avons pu analyser l'impact de ces caractéristiques sur les coefficients de réflexion et de transmission. Un gradient de propriétés matérielles de l'os est introduit, et son impact sur les coefficients d'intérêt est examiné. L'aspect modal des ondes est exploré, en étudiant la dispersion des ondes de Lamb. Les résultats obtenus dans une configuration géométrique bidimensionnelle ont permis de discuter l'influence des divers paramètres, en terme de propriétés mécaniques et/ou géométriques, sur la propagation des ondes ultrasonores dans le tissu cortical. Dans une deuxième partie, le modèle est étendu pour une configuration géométrique cylindrique. La discussion est menée afin d'analyser l'influence de la géométrie tridimensionnelle de l'os sur les phénomènes de propagation
In this thesis, we are interested in the modeling and simulation of the propagation of ultrasonic waves in the cortical bone. Precisely, we have studied and analyzed the Quantitative Ultrasound (QUS) technique for the evaluation of the quality of bone tissue. It is an emerging technique those the application to bone tissue arouses particular interest in the scientific community. Since bone tissue is a living tissue, it is subject to aging and various pathologies, such osteoporosis, osteomalacia, osteoporomalacia, or the so-called Paget disease. To assist in therapeutic follow-up of the bone, monitoring of quality of bone tissue is essential. In this context, methods based on QUS technique are deemed to be interesting, due of their non-invasive, inexpensive, portable and non-ionizing characteristics. However, use the ultrasound in the context of characterization of bone tissue, requires a deep understanding of the different physical phenomena involved in their propagation. In this perspective, our work is developed in the modeling theme dedicated to the propagation of ultrasonic waves in multidimensional, heterogeneous, anisotropic waveguides, constituted of materials whose heterogeneity can be qualified as random. One of the originalities of this thesis concerns the study of the reflection and transmission coefficients and the dispersion curves in the presence of uncertainties in the material properties. In a first part, we study the reflection/transmission phenomena via a two-dimensional tri-layer model taking into account the soft tissues and the random heterogeneity of the bone tissue. We analyzed the impact of these characteristics on the reflection and transmission coefficients. A gradient of material properties is introduced, and its effect on the coefficients of interest is examined. The modal aspect of the waves is explored, by studying the dispersion of Lamb waves. The results obtained in a two-dimensional geometrical configuration made it possible to discuss the influence of the various parameters, in terms of mechanical and/or geometric properties, on the propagation of the ultrasonic waves in the cortical tissue. In a second part, the proposed model is extended for a cylindrical geometric configuration. The discussion is carried out in order to analyze the influence of the three-dimensional geometry of the bone on the phenomena of propagation
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Matta, Sandrine. "Propagation des ondes acoustiques dans une multicouche composée de couches viscoélastiques liquides, solides et poreuses." Thesis, Valenciennes, 2018. http://www.theses.fr/2018VALE0035/document.

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Cette thèse propose un formalisme général pour modéliser la propagation des ondes acoustiques dans une multicouche composée de toute combinaison de couches liquides, solides élastiques isotropes et poro-élastiques isotropes, la méthode ayant la flexibilité d'être développée pour inclure d'autres natures de couches. Dans un premier lieu, un algorithme stable est développé, basé sur l'approche récursive de la matrice de rigidité, pour modéliser la propagation d'une onde plane incidente sur la multicouche en fonction de son angle d'incidence et de sa fréquence. Cet algorithme fusionne de manière récursive les matrices de rigidité des couches individuelles de la structure en une matrice de rigidité totale et permet ensuite le calcul des coefficients de réflexion et de transmission, ainsi que les composantes de déplacement et de contrainte à l'intérieur de la multicouche pour chaque direction d'incidence des ondes planes. Deuxièmement, pour modéliser la propagation d'un faisceau délimité d'ondes incidentes, la technique du spectre angulaire est utilisée, basée sur la décomposition de ce faisceau en un spectre d'ondes planes se propageant dans des directions différentes. Par la suite, le faisceau d'onde réfléchi dans le milieu d'incidence et le faisceau d'onde transmis dans le milieu de transmission, ainsi que la distribution des champs (composantes de déplacement et de contrainte) à l'intérieur de la multicouche sont obtenus en superposant la contribution de toutes les ondes planes se propageant dans les différentes directions. Comme application numérique, une tri-couche solide-poreuse-solide immergée dans l'eau est simulée. La réflexion et la transmission qui en résultent, ainsi que les composantes de déplacement et de contrainte dans la multicouche, correspondants à l’onde plane incidente et au faisceau limité incident, révèlent la stabilité du procédé et la continuité des déplacements et des contraintes aux interfaces
This thesis proposes a general formalism to model the acoustic wave propagation in a multilayer consisting of any combination of fluid, isotropic elastic solid, and isotropic poroelastic layers, the method having the flexibility to be extended to include other layer-natures. At a first stage, a stable algorithm is developed, based on the recursive stiffness matrix approach, to model the propagation of a plane wave incident on the multilayer as a function of its incidence angle and frequency. This algorithm merges recursively the structureindividual layers stiffness matrices into one total stiffness matrix and allows then the calculation of the reflection and transmission coefficients, as well as the displacement and stress components inside the multilayer for every incident plane wave direction. Secondly, to model the propagation of a bounded incident wave beam, the angular spectrum technique is used which is based on the decomposition of this beam into a spectrum of plane waves traveling in different directions. The corresponding reflected wave beam in the incidence medium, and the transmitted wave beam in the transmission medium, as well as the fields distributions (displacement and stress components) inside the multilayer are obtained by summing the contribution of all the plane waves traveling in different directions. As a numerical application, a three-layered solid-porous-solid structure immersed in water is simulated. The resulting reflection and transmission as well as the displacement and stress components in the multilayer corresponding to both, the incident plane wave in different directions and the incident bounded beam reveal the stability of the method and the continuity of the displacements and stresses at the interfaces
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Палій, Богдан Максимович. "Ультразвуковий засіб технологічного контролю поверхневої густини тканин." Master's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/38417.

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В даній магістерській дисертаційній роботі проведено аналітичне дослідження ультразвукового засобу технологічного контролю поверхневої густини тканин. Проведений аналіз показав, що для забезпечення випуску якісних тканин необхідно проведення оперативного технологічного контролю їх поверхневої густини. В теперішній час застосовуються переважно руйнівні контактні методи контролю поверхневої густини тканин, які засновані на вирізанні та зважуванні зразків тканин, тоді як безконтактні не використовуються хоча мають ряд суттєвих переваг у порівнянні з контактними. Як показав проведений у першому розділі дисертації аналіз, для оперативного технологічного контролю поверхневої густини тканин, доцільним є застосування ультразвукових методів контролю. У другому розділі дисертації розглянуті особливості розповсюдження ультразвукових хвиль в тканинах, які пов’язані з розмірами пор та іншими структурними показниками тканин, які впливають на проходження ультразвукових хвиль скрізь тканину та відбиття від неї. Проведено дослідження проходження ультразвукової хвилі крізь контрольовані тканини з різними розмірами пор і відбиття від них та отримані аналітичні залежності для розрахунку та аналізу взаємодії ультразвукових хвиль з нитками тканин з різними акустичними опорами. Отримано аналітичні залежності, які пов’язують амплітудні співвідношення ультразвукових хвиль як із зміною самих діаметрів ниток основи та утоку, так і безпосередньо з поверхневою густиною тканини. Доведено, що згасанням ультразвукових коливань для більшості тканин можна знехтувати, а вибором співвідношення об’ємної густини тканини та довжиною ультразвукової хвилі в тканині можна знизити вплив згасання на амплітудні співвідношення ультразвукових хвиль. Показано, що при збільшенні тривалості ультразвукового імпульсного сигналу зменшуються амплітудна та фазова похибки в порівнянні з безперервним сигналом. Тому необхідно вибирати тривалість ультразвукового імпульсного сигналу такою, щоб не відбувалось перевідбиттів ультразвукових хвиль від поверхні тканини та поверхонь п’єзоперетворювачів. В третьому проведена розробка ультразвукового засобу технологічного контролю поверхневої густини тканин та його експериментальні дослідження.
In this master's dissertation an analytical study of the ultrasonic means of technological control of tissue surface density. The analysis showed that to ensure the release of quality fabrics it is necessary to carry out operational technological control of their surface density. Currently, mainly destructive contact methods of tissue surface density control are used, which are based on cutting and weighing tissue samples, while non-contact ones are not used, although they have a number of significant advantages over contact ones. As shown by the analysis conducted in the first section of the dissertation, for the operational technological control of tissue surface density, it is advisable to use ultrasonic control methods. The second section of the dissertation discusses the peculiarities of the propagation of ultrasonic waves in tissues, which are related to the pore size and other structural parameters of tissues that affect the passage of ultrasonic waves through the tissue and reflection from it. A study of the passage of ultrasonic waves through controlled tissues with different pore sizes and reflections from them and obtained analytical dependences for the calculation and analysis of the interaction of ultrasonic waves with tissue threads with different acoustic resistances. Analytical dependences are obtained, which relate the amplitude ratios of ultrasonic waves both with the change of the diameters of the warp and weft threads, and directly with the surface density of the fabric. It has been shown that the attenuation of ultrasonic vibrations can be neglected for most tissues, and the choice of the ratio of the bulk density of the tissue and the length of the ultrasonic wave in the fabric can reduce the effect of attenuation on the amplitude ratio of ultrasonic waves. It is shown that as the duration of the ultrasonic pulse signal increases, the amplitude and phase errors decrease in comparison with the continuous signal. Therefore, it is necessary to choose the duration of the ultrasonic pulse signal so that there are no reflections of ultrasonic waves from the surface of the fabric and the surfaces of the piezoelectric transducers. In the third development of ultrasonic means of technological control of surface density of fabrics and its experimental researches is carried out.
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Books on the topic "Transmission and reflection coefficients"

1

Conway, G. D. Measurement of surface reflection coefficients via multiple reflection of microwaves. Saskatoon, Sask: Plasma Physics Laboratory, University of Saskatchewan, 1994.

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Rüger, Andreas. Reflection coefficients and azimuthal AVO analysis in anisotropic media. Tulsa, OK: Society of Exploration Geophysicists, 2002.

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James, Timothy B. Heat transmission coefficients for walls, roofs, ceilings, and floors. Atlanta, Ga: American Society of Heating, Refrigerating, and Air-Conditioning Engineers, 1993.

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Lekner, John. Theory of reflection: Of electromagnetic and particle waves. Dordrecht: M. Nijhoff Publishers, 1987.

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Spencer, Francis E. Applications and limitations of two important numerical methods for the computation of transmission coefficients. Monterey, Calif: Naval Postgraduate School, 1997.

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Stuck, D. Tabellen von Wärmekoeffizienten für Wasser als Wärmeträgermedium =: Tables of heat coefficients for water as heat-conveying liquid. Bremerhaven: Wirtschaftsverlag NW, 1986.

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Dobson, C. C. Laser transmission measurements of soot extinction coefficients in the exhaust plume of the X-34 60k-lb thrust fastrac rocket engine. [Marshall Space Flight Center], Ala: National Aeronautics and Space Administration, Marshall Space Flight Center, 2000.

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Weil, Claude. Intercomparison of permeability and permittivity measurements using the transmission/reflection method in 7 and 14 mm coaxial air lines. Boulder, Colo: U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, 1997.

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Reflection Coefficients & Azimuthal AVO Analysis. Society Of Exploration Geophysicists, 2002.

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Al, Kogut, and United States. National Aeronautics and Space Administration., eds. Reflection coefficients on surfaces of different periodic structure. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Book chapters on the topic "Transmission and reflection coefficients"

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Brekhovskikh, Leonid M., and Oleg A. Godin. "Universal Properties of the Plane-Wave Reflection and Transmission Coefficients." In Springer Series on Wave Phenomena, 126–43. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-52369-4_6.

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Ravelo, Blaise. "Cartographical Analyses of Reflection and Transmission Coefficients of Shunt Coupled Lines." In Analytical Methodology of Tree Microstrip Interconnects Modelling For Signal Distribution, 167–89. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-0552-2_9.

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Shimaoka, Kazuhiro, Masaaki Nemoto, Shuichi Yoshikawa, Isao Yoshida, and Yorinobu Yoshisato. "Low-Temperature Vector Network Measurement of Reflection Coefficients of Tl2Ba2CaCu2Ox/MgO/Au Transmission Lines." In Advances in Superconductivity IX, 1277–80. Tokyo: Springer Japan, 1997. http://dx.doi.org/10.1007/978-4-431-68473-2_147.

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Alpay, Daniel, Israel Gohberg, and Lev Sakhnovich. "Inverse Scattering Problem for Continuous Transmission Lines with Rational Reflection Coefficient Function." In Recent Developments in Operator Theory and Its Applications, 1–16. Basel: Birkhäuser Basel, 1996. http://dx.doi.org/10.1007/978-3-0348-9035-9_1.

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Madigosky, W., R. Fiorito, and H. Überall. "A New Theory for the Transmission and Reflection Coefficient of Layered Systems." In Adaptive Methods in Underwater Acoustics, 103–9. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5361-1_9.

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Yang, Ran, Ning Wei, Zheng Dong, Hongji Xu, and Ju Liu. "Robust Transmission Design for IRS-Aided MISO Network with Reflection Coefficient Mismatch." In Communications and Networking, 140–50. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-99200-2_12.

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Atkinson, D. "Reflection Coefficients and Poles." In Nonlinear Evolution Equations and Dynamical Systems, 68–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 1990. http://dx.doi.org/10.1007/978-3-642-84039-5_12.

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Cohen, Gary C. "Reflection-Transmission Analysis." In Scientific Computation, 145–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04823-8_10.

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Lu, Wei, and Ying Fu. "Reflection and Transmission." In Springer Series in Optical Sciences, 73–106. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-94953-6_3.

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Zaitsev, Alexander M. "Reflection and Transmission." In Optical Properties of Diamond, 13–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-662-04548-0_2.

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Conference papers on the topic "Transmission and reflection coefficients"

1

Wapenaar, K. "Reflection and Transmission Coefficients of Self-Similar Interfaces." In 60th EAGE Conference and Exhibition. European Association of Geoscientists & Engineers, 1998. http://dx.doi.org/10.3997/2214-4609.201408288.

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Oughstun, Kurt E., and Christopher L. Palombini. "Fresnel reflection and transmission coefficients for complex media." In 2017 XXXIInd General Assembly and Scientific Symposium of the International Union of Radio Science (URSI GASS). IEEE, 2017. http://dx.doi.org/10.23919/ursigass.2017.8105357.

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Imhof, Matthias G. "Scale and frequency dependence of reflection and transmission coefficients." In SEG Technical Program Expanded Abstracts 1998. Society of Exploration Geophysicists, 1998. http://dx.doi.org/10.1190/1.1820247.

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Mneg, Fanji, Rugui Yang, and Huaqing Xiao. "Improved Reflection and Transmission Coefficients of Frequency Selective Surfaces." In 2006 7th International Symposium on Antennas, Propagation & EM Theory. IEEE, 2006. http://dx.doi.org/10.1109/isape.2006.353348.

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Liu, Yang, Kuisong Zheng, Zongmin Mu, and Xiangpeng Liu. "Reflection and transmission coefficients of moving dielectric in half space." In 2016 11th International Symposium on Antennas, Propagation and EM Theory (ISAPE). IEEE, 2016. http://dx.doi.org/10.1109/isape.2016.7834032.

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Stovas, A., and B. Ursin. "Reflection and Transmission Coefficients Between Two Visco-Elastic TIV Media." In 62nd EAGE Conference & Exhibition. European Association of Geoscientists & Engineers, 2000. http://dx.doi.org/10.3997/2214-4609-pdb.28.p148.

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Li, Gui Ping, Jun Xu, Mao Yan Wang, San Qiang Tong, and Hai Long Li. "Reflection, transmission and absorption coefficients of a dusty plasma slab." In 2016 URSI International Symposium on Electromagnetic Theory (EMTS). IEEE, 2016. http://dx.doi.org/10.1109/ursi-emts.2016.7571462.

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Hung-Wen Chang. "3-D reflection/transmission coefficients from cylindrical layered elastic media." In IEEE 1987 Ultrasonics Symposium. IEEE, 1987. http://dx.doi.org/10.1109/ultsym.1987.199000.

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9

Stolte, James, and Joseph M. Santiago. "Determination of Reflection and Transmission Coefficients in Rigidly Connected Beams Using Timoshenko Beam Theory." In ASME 1996 Design Engineering Technical Conferences and Computers in Engineering Conference. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-detc/cie-1614.

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Abstract Knowledge of the behavior of a wave incident at a joint is necessary to properly analyze the vibration of a structure. We need to know how much energy is reflected and transmitted and also the type of wave carrying the energy. Typically, Euler beam theory is used to derive the reflection and transmission coefficients at high frequencies. Errors can become unacceptably large in the frequency range currently being analyzed using Statistical Energy Analysis (SEA) and the Power Flow Finite Element Method (PFFEM). We derive reflection and transmission coefficients due to a bending wave incident on a rigid joint between two infinitely long beams using Timoshenko theory and compare results to those obtained using Euler theory. We also compute the reflection and transmission efficiencies that determine the amount of power carried by each wave.
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Orlov, A. A., E. A. Yankovskaya, S. V. Zhukovsky, V. E. Babicheva, and P. A. Belov. "Retrieving constitutive parameters of plasmonic multilayers from reflection and transmission coefficients." In 2014 8th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS). IEEE, 2014. http://dx.doi.org/10.1109/metamaterials.2014.6948571.

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Reports on the topic "Transmission and reflection coefficients"

1

Isakson, Marcia J. High Frequency Acoustic Reflection and Transmission in Ocean Sediments. Fort Belvoir, VA: Defense Technical Information Center, September 2006. http://dx.doi.org/10.21236/ada612088.

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Isakson, Marcia J. High Frequency Acoustic Reflection and Transmission in Ocean Sediments. Fort Belvoir, VA: Defense Technical Information Center, September 2009. http://dx.doi.org/10.21236/ada531414.

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Isakson, Marcia J. High Frequency Acoustic Reflection and Transmission in Ocean Sediments. Fort Belvoir, VA: Defense Technical Information Center, September 2007. http://dx.doi.org/10.21236/ada541171.

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Isakson, Marcia J. High Frequency Acoustic Reflection and Transmission in Ocean Sediments. Fort Belvoir, VA: Defense Technical Information Center, September 2011. http://dx.doi.org/10.21236/ada571663.

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Hurricane, O. A., and P. L. Miller. Shock transmission and reflection from a material interface and subsequent reflection from a hard boundary. Office of Scientific and Technical Information (OSTI), November 1998. http://dx.doi.org/10.2172/6132.

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Berman, David H. Effective Reflection Coefficients for the Mean Acoustic Field Between Two Rough Interfaces. Fort Belvoir, VA: Defense Technical Information Center, February 1994. http://dx.doi.org/10.21236/ada281962.

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Aldridge, David F. Reflection and Transmission of Plane Electromagnetic Waves by a Geologic Layer. Office of Scientific and Technical Information (OSTI), April 2017. http://dx.doi.org/10.2172/1367459.

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Shellman, C. H. A New Version of MODESRCH using Interpolated Values of the Magnetoionic Reflection Coefficients. Fort Belvoir, VA: Defense Technical Information Center, August 1986. http://dx.doi.org/10.21236/ada179094.

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Abeyaratne, Rohan, and James K. Knowles. Reflection and Transmission of Waves from an Interface with a Phase- Transforming Solid. Fort Belvoir, VA: Defense Technical Information Center, September 1991. http://dx.doi.org/10.21236/ada242455.

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10

Oughston, Kurt. The Asymptotic Theory of the Reflection and Transmission of a Pulsed Electromagnetic Beam Field at a Planar Interface Separating Two Dispersive Media. Fort Belvoir, VA: Defense Technical Information Center, March 1993. http://dx.doi.org/10.21236/ada269033.

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