scholarly journals Реализация и производительность алгоритмов волновой томографии на вычислительных платформах SIMD CPU и GPU

2021 ◽  
pp. 322-332
Author(s):  
A.V. Goncharsky ◽  
S.Y. Romanov ◽  
S.Y. Seryozhnikov
Keyword(s):  
Gpu Computing ◽  
Fdtd Method ◽  
Graphics Processors ◽  
Practical Applications ◽  
Tomographic Image Reconstruction ◽  
Coefficient Inverse Problems ◽  
Gradient Based ◽  
Wave Tomography ◽  
Computing Platforms ◽  
Difference Time

This paper is concerned with implementation of wave tomography algorithms on modern SIMD CPU and GPU computing platforms. The field of wave tomography, which is currently under development, requires powerful computing resources. Main applications of wave tomography are medical imaging, nondestructive testing, seismic studies. Practical applications depend on computing hardware. Tomographic image reconstruction via wave tomography technique involves solving coefficient inverse problems for the wave equation. Such problems can be solved using iterative gradient-based methods, which rely on repeated numerical simulation of wave propagation process. In this study, finite-difference time-domain (FDTD) method is employed for wave simulation. This paper discusses software implementation of the algorithms and compares the performance of various computing devices: multi-core Intel and ARM-based CPUs, NVidia graphics processors. В данной статье рассматривается реализация алгоритмов волновой томографии на современных вычислительных платформах SIMD CPU и GPU. Область волновой томографии, которая в настоящее время находится в стадии разработки, требует мощных вычислительных ресурсов. Основные области применения волновой томографии - это медицинская визуализация, неразрушающий контроль, сейсмические исследования. Практические приложения зависят от вычислительного оборудования. Восстановление томографического изображения методом волновой томографии включает решение коэффициентов обратной задачи для волнового уравнения. Такие проблемы могут быть решены с помощью итерационных градиентных методов, основанных на многократном численном моделировании процесса распространения волн. В этом исследовании для моделирования волн используется метод конечных разностей во временной области (FDTD). В статье обсуждается программная реализация алгоритмов и сравнивается производительность различных вычислительных устройств: многоядерных процессоров Intel и ARM, графических процессоров NVidia.

scholarly journals Designing the Hotspots Distribution by Anisotropic Growth

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 187
Author(s):  
Tianshun Li ◽  
Renxian Gao ◽  
Xiaolong Zhang ◽  
Yongjun Zhang
Keyword(s):  
Au Nanoparticles ◽  
Fdtd Method ◽  
Polarization Dependence ◽  
Noble Metal Nanoparticles ◽  
Oblique Angle Deposition ◽  
Matlab Simulation ◽  
Different Shapes ◽  
Plasma Enhancement ◽  
Difference Time ◽  
Good Agreement

Changing the morphology of noble metal nanoparticles and polarization dependence of nanoparticles with different morphologies is an important part of further research on surface plasma enhancement. Therefore, we used the method based on Matlab simulation to provide a simple and effective method for preparing the morphologies of Au nanoparticles with different morphologies, and prepared the structure of Au nanoparticles with good uniformity and different morphologies by oblique angle deposition (OAD) technology. The change of the surface morphology of nanoparticles from spherical to square to diamond can be effectively controlled by changing the deposition angle. The finite difference time domain (FDTD) method was used to simulate the electromagnetic fields of Au nanoparticles with different morphologies to explore the polarization dependence of nanoparticles with different shapes, which was in good agreement with Raman spectrum.

The Lightning Electromagnetic Pulse Coupling Effect Inside the Shielding Enclosure With Penetrating Wire

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Xue Jiao ◽  
Bo Yang
Keyword(s):  
Electromagnetic Pulse ◽  
Coupling Effect ◽  
Fdtd Method ◽  
Current Source ◽  
Low Frequency ◽  
Frequency Component ◽  
Lightning Current ◽  
Proper Size ◽  
Practical Engineering ◽  
Difference Time

AbstractTo study the lightning electromagnetic pulse (LEMP) coupling and protection problems of shielding enclosure with penetrating wire, we adopt the model with proper size which is close to the practical engineering and the two-step finite-difference time-domain (FDTD) method is used for calculation in this paper. It is shown that the coupling voltage on the circuit lead inside the enclosure increases about 34 dB, when add 1.0 m long penetrating wire at the aperture, comparing with the case without penetrating wire. Meanwhile, the waveform, has the same wave outline as the lightning current source, shows that the penetrating wire brings a large number of low frequency component into the enclosure. The coupling effect in the enclosure will reduce greatly when penetrating wire has electrical connection with the enclosure at the aperture and the coupling voltage increase only about 12 dB than the case without penetrating wire. Moreover, the results show that though the waveguide pipe can reduce the coupling effect brought by the penetrating wire, the exposing part of penetrating wire can increase the coupling when the penetrating wire outside the enclosure is longer than the waveguide pipe and the longer the exposing part is, the stronger the coupling is.

Trapping of Nano-Particles Using a Near-Field Optical Fiber Probe

2012 ◽  
Vol 516 ◽  
pp. 90-95
Author(s):  
Bing Hui Liu ◽  
Li Jun Yang ◽  
Yang Wang
Keyword(s):  
Near Field ◽  
Fdtd Method ◽  
Laser Wavelength ◽  
Nano Particles ◽  
Minimum Size ◽  
Fiber Probe ◽  
Circular Shape ◽  
Optical Fiber Probe ◽  
Fibre Probe ◽  
Difference Time

By employing a generalization of the conservation law for momentum using the finite difference time domain (FDTD) method, the feasibility of using a near-field optical fibre probe to create near-field optical trapping is investigated. Numerical results indicate that the scheme is able to trap nanoparticles with diameters of tens of nanometres in a circular shape with lower laser intensity. Using the built system with a tapered metal-coated fibre probe, 120 nm polystyrene particles are trapped in a multi-circular shape with a minimum size of 400 nm. They are at a resolution of λ/7 (λ: laser wavelength) and d (d: tip diameter of fiber probe), respectively.

Investigation of Contact Conditions During Stamping of a Thin Plate

2020 ◽  
Author(s):  
Harshal Y. Shahare ◽  
Rohan Rajput ◽  
Puneet Tandon
Keyword(s):  
Wave Propagation ◽  
Material Properties ◽  
High Speed ◽  
Fdtd Method ◽  
Propagation Model ◽  
Transmitted Wave ◽  
Two Dimensional ◽  
Contact Conditions ◽  
Simulation Based ◽  
Difference Time

Abstract Stamping is one of the most used manufacturing processes, where real-time monitoring is quite difficult due to high speed of the mechanical press, which leads to deterioration of the accuracy of the products In the present work, a method is developed to model elastic waves propagation in solids to measure contact conditions between die and workpiece during stamping. A two-dimensional model is developed that reduces the wave propagation equations to two-dimensional equations. To simulate the wave propagation inside the die-workpiece model, the finite difference time domain (FDTD) method and modified Yee algorithm has been employed. The numerical stability of the wave propagation model is achieved through courant stability condition, i.e., Courant-Friedrichs-Lewy (CFL) number. Two cases, i.e., flat die-workpiece interface and inclined die-workpiece interface, are investigated in the present work. The elastic wave propagation is simulated with a two-dimension (2D) model of the die and workpiece using reflecting boundary conditions for different material properties. The experimental and simulation-based results of reflected and transmitted wave characteristics are compared for different materials in terms of reflected and transmitted wave height ratio and material properties such as acoustic impedance. It is found that the numerical simulation results are in good agreement with the experimental results.

scholarly journals Fully three-dimensional analysis of a photonic crystal assisted silicon on insulator waveguide bend

2018 ◽  
Vol 32 (31) ◽  
pp. 1850344 ◽  
Author(s):  
N. Eti ◽  
Z. Çetin ◽  
H. S. Sözüer
Keyword(s):  
Photonic Crystal ◽  
Numerical Study ◽  
Fdtd Method ◽  
Three Dimensional ◽  
Silicon On Insulator ◽  
Geometrical Parameters ◽  
Low Loss ◽  
Bending Loss ◽  
Difference Time ◽  
Waveguide Bend

A detailed numerical study of low-loss silicon on insulator (SOI) waveguide bend is presented using the fully three-dimensional (3D) finite-difference time-domain (FDTD) method. The geometrical parameters are optimized to minimize the bending loss over a range of frequencies. Transmission results for the conventional single bend and photonic crystal assisted SOI waveguide bend are compared. Calculations are performed for the transmission values of TE-like modes where the electric field is strongly transverse to the direction of propagation. The best obtained transmission is over 95% for TE-like modes.

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