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IEEE Asia-Pacific Microwave Conference (APMC)

作者： Chakraborty, Samik Chakraborty, Ayona Gupta, Bhaskar Chatterjee, Sayan Dream Inst Technol Elect & Commun Engn Kolkata India Jadavpur Univ Elect & Telecommun Engn Dept Kolkata India

ISBN: (纸本)9781728135175

Dielectric antennas do not have metal component which makes them useful at high frequencies where metallization loss is a factor. Dielectric rectangular slab antenna is widely used in mobile, satellite, communication systems due to its high performance. Dielectric antennas are highly functional at high frequencies (specifically < 1GHz) due to easy manufacturing, low loss, less corrosive and can be sealed with ease. Two dielectric slab antennas have been studied here in the same frequency band (842 GHz) specifically for onboard aerospace applications. The antennas can be widely used for aeronautical radio navigation service (ARNS) and also for airborne ground mapping and weatherforecasting.

关键词： dielectric antenna impedance matching dual frequency rectangular slab waveguide WR 90

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Wave theory-based fourth harmonic generation of Bessel-Gauss beam by total internal reflection-quasi phase matching in a rectangular slab of beta barium borate

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OPTICAL ENGINEERING 2022年第12期61卷 125106-125106页

作者： Saha, Jaya Deb, Sumita Natl Inst Technol Agartala Dept Elect Engn Agartala Tripura West India

This work presents a theoretical approach to a highly multimode-guided wave-based fourth harmonic (FH) generation method by exploiting a zero-order Bessel-Gauss beam through the total internal reflection quasi phase-matching technique. An anisotropic crystal featuring a rectangular structure of beta barium borate has been used to carry out this analysis. In contrast to the conventional frequency conversion scheme using a Gaussian beam, the projected scheme yields a maximum six times superior efficiency of 6.9547% in a crystal length of nearly 6.3 mm, corresponding to a 266-nm FH wavelength. The analysis has also taken into account optical losses, such as absorption, Goos-Hanchen-shift, surface roughness, and the effect of the nonlinear law of reflection. Finally, a systematic study has been performed to describe the influence of parametric modification, such as variations in slab length and thickness, to provide a more comprehensive picture of the overall analysis.

关键词： fourth harmonic generation Bessel-Gauss beam total internal reflection-quasi phase matching rectangular slab nonlinear guided wave theory

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Evaluation of Shrinking Direction of Movement Using Monte Carlo Simulation in A rectangular slab

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Procedia Manufacturing 2019年 35卷 1370-1374页

作者： N.E. Udoye A.A. Dare O.S.I. Fayomi D.C. Uguru-okorie Department of Mechanical Engineering College of Engineering Covenant University Ota Lagos state Nigeria Department of Mechanical Engineering Faculty of Technology University of Ibadan Oyo state Nigeria Department of Mechanical Engineering Science University of Johannesburg South Africa Department of Mechanical Engineering College of Engineering Landmark University Kwara State Nigeria

Heat transfer is frequently encountered in everyday life and in engineering practice. As such there is constant urge to explore new approach for its numerical estimation. Monte Carlo being relatively untapped tool is explored in this work. A model was developed using Shrinking Boundary Monte Carlo Method for analysis of steady state heat conduction in a rectangular slab. The model was used to obtain temperature distribution in a Zig-zag manner, rectangular left to right, rectangular right to left. The result of which was compared to ordinary Monte Carlo Method. The computational run time for each of the shrinking pattern was determined. The study established that the average of the run time for various sizes of the slab indicates that horizontal left to right is shorter. It is the best ways of calculating temperature distribution in a rectangular slab of fixed boundary temperature. Horizontal left to right is also good for larger network calculation as used in Shrinking Boundary Methods. Application of the shrinking boundary Monte Carlo Methods to study heat conduction in rectangular slabs yielded favourable results. The obtained results are close to those obtained by finite difference technique. The different shrinking directions of movement for a given size of a rectangular slab have the same surface graph and % deviation. The maximum deviation was not more than 11.5 with deviation of 2.9% for temperature distribution in a rectangular slab with boundary conditions.

关键词： Monte-carlo method heat transfer temperature distribution rectangular slab

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Ultimate bearing capacity of RC rectangular slab considering membrane effect

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Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology 2007年第6期29卷 58-61页

作者： Zhang, Xian-Jin Li, Yong-Chun Lu, Man-Man School of Civil Engineering and Mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China Hubei Key Laboratory of Control Structure Huazhong Univ. of Sci. and Technol. Wuhan 430074 China Department of Civil Engineering Beihang University Beijing 100083 China

Based on plastic yield line theory the failure model of horizontal restrained rectangular slab was given. By applying principle of virtual work, the formula of horizontal restrained rectangular slab for calculation of limit bearing capacity was derived. The average compression zone height needed to be determined. By nonlinear regression of the results with MATLAB, the formula of compression zone depth could be obtained. Comparative analysis showed that the formula was in good agreement with experimental values.

关键词： Finite element analysis Membrane effect Plastic yield line theory rectangular slab Ultimate bearing capacity

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Analytical design of fourth and fifth harmonic generations of an elliptically polarized Bessel-Gauss beam by using the concept of guided wave optics and TIR-QPM technique in a biaxial material

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JOURNAL OF NONLINEAR OPTICAL PHYSICS & MATERIALS 2025年第8期34卷

作者： Saha, Jaya Deb, Sumita Natl Inst Technol Agartala Dept Elect Engn Jirania 799046 Tripura India

This paper demonstrates the analytical design of an Elliptically polarized Bessel-Gauss beam-based frequency converter by using the guided wave optics concept and Total Internal Reflection Quasi phase matching technique. An anisotropic positive biaxial crystal featuring a rectangular structure of Rubidium Titanyle Phosphate has been used to carry out this analysis. The efficiency of the fourth and fifth harmonic conversion in the projected scheme is 7.05% and 4.3%, respectively, which is approximately three times greater than in a crystal length of approximately 1.4mm and 3.4mm, as provided by the scheme illuminated by a linearly polarized Bessel-Gauss beam at a wavelength of 735nm and 588nm, respectively. The influence of limiting factors, viz Goos H & auml;nchen Shift, surface roughness, absorption, and the diffraction effect rooted in the basic law of nonlinear reflection, has also been taken care of in this analysis. The dependence of conversion efficiency on the length, thickness and angle of incidence of the slab has also been studied.

关键词： Elliptically polarized beam generalized gaussian beam Bessel-gauss beam TIR-QPM rectangular slab biaxial crystal RTP multimode guided wave theory

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DYNAMIC MOTION OF RC BEAMS AND ONE-WAY slabS IMPACTED BY A MISSILE AT MEDIUM VELOCITY: MODELS FOR SPREADSHEET APPLICATION

DYNAMIC MOTION OF RC BEAMS AND ONE-WAY SLABS IMPACTED BY A M...

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18th International Conference on Nuclear Engineering (ICONE-18)

作者： Rambach, Jean-Mathieu Inst Radioprotect & Surete Nucl Fontenay Aux Roses France

ISBN: (纸本)9780791849330

This paper deals with the simulation of the motion of a one-span slender rectilinear RC beam or a thin one-way RC rectangular slab when impacted by a missile, within and beyond the elastic domain, up to a maximal displacement equal to the height of the section. The loading is variable in time and in space and the supporting conditions at each extremity are either of simply resting type or of clamping type. The equation of motion for each beam segment is expressed, through finite differences method, by relations between velocity and flexural moment that are decomposed on the basis of the first N modes of beam deformation. The plastic deformations are taken into account by constraining the flexural moment to follow elastic/perfectly plastic flexural moment - curvature law. The algorithms are well adapted to a spreadsheet application that allows easily: i) presizing such a structure against this type of loading, ii) the sensitivity studies regarding the mechanical parameters, iii) checking the order of magnitude of the results of big FEM models by using highly sophisticated codes. Simulations by this method show good agreement with experimental results and give access to some mechanical properties of the structure when damaged.

关键词： beam rectangular slab plate dynamic motion elastic-perfectly plastic bending moment / curvature law finite differences spreadsheet application impact

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Fourth harmonic generation of Laguerre Gaussian beam in BBO crystal by total internal reflection-quasi phase matching technique

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OPTIK 2022年 254卷 168689-168689页

作者： Saha, Jaya Deb, Sumita Natl Inst Technol Dept Elect Engn Agartala 799046 India

This work deals with analytical exploration of a highly multimodal nonlinear guided wave approach based Fourth harmonic frequency conversion scheme of Laguerre Gaussian beam through Total Internal Reflection Quasi phase matching technique. The analysis has been carried out in a rectangular slab geometry of anisotropic crystal made of Beta beryllium borate. Compared to the traditional Gaussian beam-based frequency conversion scheme, the proposed scheme achieves nearly 7 times better efficiency of 4.8% in a 2.6 mm long crystal corresponding to an application wavelength of 266 nm. The optical losses like absorption, GH-shift, reflection, and effect due to nonlinear law of reflection have also been incorporated in the analysis. The impact of various parametric changes like variations in slab length and thickness has also been studied to give a better perspective of the whole analysis.

关键词： Fourth harmonic generation Laguerre Gaussian beam TIR-QPM rectangular slab Anisotropic crystal BBO Waveguide Non-linear guided wave theory

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