Reflection coefficient

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1 - Evolution of solitons and their reflection and transmission in a plasma having negatively charged dust grains
Renu Tomar Anjali Bhatnagar Hitendra K. Malik Raj P. Dahiya

10.1007/s40094-014-0138-4

AbstractTheoretical calculations are carried out for studying soliton’s reflection and transmission in an inhomogeneous plasma comprising ions, two temperature electrons and negatively charged dust grains. Using reductive perturbation technique, relevant modified KdV eq أکثر

AbstractTheoretical calculations are carried out for studying soliton’s reflection and transmission in an inhomogeneous plasma comprising ions, two temperature electrons and negatively charged dust grains. Using reductive perturbation technique, relevant modified KdV equations are derived for the incident, reflected and transmitted solitons. Then a coupled equation is obtained based on these mKdV equations, which is solved for the reflected soliton under the use of solutions of mKdV equations corresponding to the incident and transmitted solitons. Based on the ratio of amplitudes of reflected and incident solitons, reflection coefficient is examined under the effect of dust grain density; the same is done for the transmission coefficient which is the ratio of amplitudes of transmitted and incident solitons. The transmission of the solitons becomes weaker under the effect of stronger magnetic field and higher dust density. However, this leads to the stronger reflection of the soliton. تفاصيل المقالة

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2 - Reflection of ion acoustic solitary waves in a dusty plasma with variable charge dust
Renu Tomar Hitendra K. Malik Raj P. Dahiya

10.1007/s40094-014-0126-8

AbstractAn inhomogeneous plasma comprising ions, two temperature electrons and dust grains with variable charge is explored for its unperturbed state for ions’ drift due to density gradient and perturbed state for the evolution of ion acoustic solitary waves and their r أکثر

AbstractAn inhomogeneous plasma comprising ions, two temperature electrons and dust grains with variable charge is explored for its unperturbed state for ions’ drift due to density gradient and perturbed state for the evolution of ion acoustic solitary waves and their reflection under the effect of an external magnetic field. The ion drift velocity is found to depend on the plasma parameters and magnetic field. The perturbed state of plasma supports two types of ion acoustic waves, which evolve into fast and slow compressive solitary structures under certain conditions. However, only the fast solitary wave is observed to be reflected and acquired opposite polarity to that of the incident solitary wave. The solitary waves are found to be downshifted after their reflection. The reflection coefficient acquires higher values in the case of dust grains of fixed charge in comparison with the case of fluctuating charge on the dust grains. It means the reflection becomes stronger when the charge on the dust grains does not fluctuate and remains fixed. The effect of dust grain density is to enhance the amplitude of solitary waves but to weaken their reflection. The amplitudes of both the incident and reflected solitons remain higher for the case of fluctuating charge on the dust grains in comparison with the case of fixed charge. The effective temperature of the plasma is also found to alter the solitary structures significantly in the case of dust grains having fluctuating charge. تفاصيل المقالة

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3 - Impact of Initial Stress on Reflection and Transmission of SV-Wave between Two Orthotropic Thermoelastic Half-Spaces
B Prasad S Kundu P Chandra Pal

10.22034/jsm.2019.572416.1307

Reflection and transmission of plane waves between two initially stressed thermoelastic half-spaces with orthotropic type of anisotropy is studied. Incidence of a SV-type wave from the lower half-space is considered and the amplitude ratios of the reflected and transmit أکثر

Reflection and transmission of plane waves between two initially stressed thermoelastic half-spaces with orthotropic type of anisotropy is studied. Incidence of a SV-type wave from the lower half-space is considered and the amplitude ratios of the reflected and transmitted SV-wave, P-wave and thermal wave are obtained by using appropriate boundary conditions. Numerical computation for a particular model is performed and graphs are plotted to study the effect of angle of incidence of the wave and the initial stress parameters of the half-spaces. From the graphical results, it is found that the modulus of reflection and transmission coefficients of the thermal wave is very less in comparison to reflection and transmission coefficients of P- and SV-waves. It is also observed that for vertical incidence of SV-wave we have only reflected and refracted SV-waves and there is no reflected or refracted P and thermal waves, whereas for horizontal incidence of SV-wave there exists only reflected SV-wave and no other reflected or transmitted wave exists. Moreover, it is found that all the reflection and transmission coefficients are strongly affected by the initial stress parameters of the both half-spaces. تفاصيل المقالة

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4 - Reflection From Free Surface of a Rotating Generalized Thermo-Piezoelectric Solid Half Space
Baljeet Singh B Singh

The analysis of rotational effect on the characteristics of plane waves propagating in a half space of generalized thermo-piezoelectric medium is presented in context of linear theory of thermo-piezoelectricity including Coriolis and centrifugal forces. The governing eq أکثر

The analysis of rotational effect on the characteristics of plane waves propagating in a half space of generalized thermo-piezoelectric medium is presented in context of linear theory of thermo-piezoelectricity including Coriolis and centrifugal forces. The governing equations for a rotating generalized thermo-piezoelectric medium are formulated and solved for plane wave solutions to show the propagation of three quasi plane waves in the medium. A problem on the reflection of these plane waves is considered from a thermally insulated/isothermal boundary of a rotating generalized thermo-piezoelectric solid half space. The expressions for reflection coefficients of three reflected waves are obtained in explicit from. For experimental data of LiNbO3 and BaTiO3, the speeds of various plane waves are computed. The reflection coefficients of various reflected waves are also obtained numerically by using the data of BaTiO3. The dependence of speeds of plane waves and reflection coefficients of various reflected waves is shown graphically on the rotation parameter at each angle of incidence. تفاصيل المقالة

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5 - Propagation of Waves at an Interface of Heat Conducting Elastic Solid and Micropolar Fluid Media
R Kumar M Kaur S.C Rajvanshi

The present investigation is concerned with the reflection and transmission coefficients of plane waves at the interface of generalized thermoelastic solid half space and heat conducting micropolar fluid half- space. The amplitude ratios of various reflected and transmi أکثر

The present investigation is concerned with the reflection and transmission coefficients of plane waves at the interface of generalized thermoelastic solid half space and heat conducting micropolar fluid half- space. The amplitude ratios of various reflected and transmitted waves with various angle of incidence have been computed numerically and depicted graphically. Micropolarity and thermal relaxation effects are shown on the amplitude ratios for specific model. Some special and particular cases are also deduced from the present investigation. تفاصيل المقالة

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6 - Reflection of Plane Wave at Traction-Free Surface of a Pre-Stressed Functionally Graded Piezoelectric Material (FGPM) Half-Space
P.K Saroj S.A Sahu

This paper is devoted to study a problem of plane waves reflection at a traction-free surface of a pre-stressed functionally graded piezoelectric material (FGPM). The effects of initial stress and material gradient on the reflection of plane waves are studied in this pa أکثر

This paper is devoted to study a problem of plane waves reflection at a traction-free surface of a pre-stressed functionally graded piezoelectric material (FGPM). The effects of initial stress and material gradient on the reflection of plane waves are studied in this paper. Secular equation has been derived analytically for the pre-stressed FGPM half-space and used to show the existence of two coupled waves namely and Continuity condition of stress, electrical potential and electrical displacement at traction free surface is used to obtain the reflection coefficient of and waves. Results of the problem are shown graphically and effects of initial stress and material gradient are discussed for a particular case of Lithium niobate material. تفاصيل المقالة

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7 - بررسی تحلیلی و عددی انعکاس امواج فراصوت هدایت شده از سطح عیب خوردگی در لوله
پژمان تقی پور بیرگانی

در این مقاله ضریب بازتاب امواج فراصوت هدایت شده از سطح یک عیب خوردگی محیطی جهت یافتن رابطه‌ای بین این ضریب و اندازه‌ی عیب بررسی شده‌است. در ابتدا با حل معادلات حاکم بر انتشار موج به روش ماتریس کلی و با توجه به شرایط مرزی موجود در لوله، نمودارهای تجزیه سرعت فاز و سرعت گر أکثر

در این مقاله ضریب بازتاب امواج فراصوت هدایت شده از سطح یک عیب خوردگی محیطی جهت یافتن رابطه‌ای بین این ضریب و اندازه‌ی عیب بررسی شده‌است. در ابتدا با حل معادلات حاکم بر انتشار موج به روش ماتریس کلی و با توجه به شرایط مرزی موجود در لوله، نمودارهای تجزیه سرعت فاز و سرعت گروه استخراج شده، سپس شبیه‌سازی انتشار موج با استفاده از نرم‌افزار اجزاء محدود آباکوس انجام شده است. به منظور تولید موج در لوله از مود طولی (2,0)L که از خصوصیات فرکانسی مناسبی برخوردار است استفاده شده است. پس از بررسی هم‌گرایی، انتشار موج در لوله‌ی دارای عیب با ابعاد مختلف بررسی شده است. در شبیه‌سازی انتشار موج، بخشی از موج تولید شده پس از برخورد به عیب، انعکاس پیدا کرده و مودهای مختلفی حاصل شده که با محاسبه‌ی سرعت مودهای بازگشتی و مقایسه‌ی این سرعت‌ها با نمودار تجزیه سرعت گروه در فرکانس 170 کیلوهرتز، اولین مود بازتابی مود (2,0)L و دومین مود بازتابی، مود (2,1)F می‌باشد. با توجه به ابعاد مختلف عیب، ضرایب بازتاب مختلفی حاصل شده و مشاهده شده که با افزایش عمق عیب، ضریب انعکاس موج بازتابی طولی نیز افزایش پیدا می‌کند. در این مقاله همچنین تاثیر پهنای خوردگی محیطی بر روی ضریب انعکاس موج طولی نیز بررسی شده و مشاهده شده که ضریب انعکاس امواج فقط به عمق عیب بستگی داشته و با تغییر پهنای خوردگی محیطی تغییر چندانی ندارد. تفاصيل المقالة

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8 - Sensitivity Analysis of Mike21-BW Diffraction Model by using Breakwater Reflection Coefficient
H Rabiefar A Akbarpour M Pourlak

DHI-Mike Software is one of best softwares describing water wave diffraction in onshore/offshore concepts. Diffraction happens due to obstacles along wave direction and has an important role in designing structures. The scope of this study is to show the relation betwee أکثر

DHI-Mike Software is one of best softwares describing water wave diffraction in onshore/offshore concepts. Diffraction happens due to obstacles along wave direction and has an important role in designing structures. The scope of this study is to show the relation between Porosity Coefficient and its effects on Diffraction Coefficient (Cd) by means of a suitable and verified numerical model. Porosity Coefficient is one of the breakwaters’ characteristics that describe the reflection quantity of the wave that influences on Diffraction Coefficient. This parameter determines the quantity of obstacles porosity and helps in implementing the sensitivity analysis. A calibrated Model helps as a suitable background to examine different Porosity Coefficients. Reputed "Wave Diffraction Diagrams" has been used for model calibration and will be discussed in detail in an appropriate section. It has been concluded that by increasing the Porosity Coefficient, wave height and Diffraction Coefficient increase. تفاصيل المقالة

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