scholarly journals Surface Dyakonov–Cherenkov radiation

eLight ◽  
2022 ◽  
Vol 2 (1) ◽  
Author(s):  
Hao Hu ◽  
Xiao Lin ◽  
Liang Jie Wong ◽  
Qianru Yang ◽  
Dongjue Liu ◽  
...  
Keyword(s):  
Particle Velocity ◽  
Cherenkov Radiation ◽  
Particle Trajectory ◽  
Particle Identification ◽  
Cherenkov Detectors ◽  
Birefringent Crystal ◽  
Enhanced Sensitivity ◽  
Radiation Enhancement ◽  
New Type ◽  
Particle Velocities

AbstractRecent advances in engineered material technologies (e.g., photonic crystals, metamaterials, plasmonics, etc.) provide valuable tools to control Cherenkov radiation. In all these approaches, however, the particle velocity is a key parameter to affect Cherenkov radiation in the designed material, while the influence of the particle trajectory is generally negligible. Here, we report on surface Dyakonov–Cherenkov radiation, i.e. the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal. This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory, e.g. we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction. Moreover, close to the Cherenkov threshold, such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors. These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform. The surface Dyakonov–Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification, but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.

Cherenkov detectors

2020 ◽  
pp. 437-476
Author(s):  
Hermann Kolanoski ◽  
Norbert Wermes
Keyword(s):  
Emission Intensity ◽  
Cherenkov Radiation ◽  
Physical Phenomenon ◽  
Particle Identification ◽  
Cherenkov Detectors ◽  
Particle Detection ◽  
Detection And Identification ◽  
Imaging Detectors ◽  
Cherenkov Ring ◽  
Ring Imaging

Particles passing through a medium with a velocity larger than that of light in that medium emit electromagnetic radiation, called Cherenkov radiation. In this chapter the physical phenomenon and characteristic parameters of Cherenkov radiation, such as Cherenkov angle, spectrum and emission intensity, are introduced and the applications for particle detection and identification are discussed. It follows a presentation of the relevant detector types, such as threshold and differential Cherenkov detectors, ring imaging detectors (RICH and DIRC) as well as Cherenkov detectors in astroparticle experiments. The obtainable resolutions for particle identification via Cherenkov ring imaging and their limitations are discussed as well.

Irregular Wave and Current Loads on a Fish Farm System

2018 ◽  
Author(s):  
Arnt G. Fredriksen ◽  
Basile Bonnemaire ◽  
Øyvind Nilsen ◽  
Leiv Aspelund ◽  
Andreas Ommundsen
Keyword(s):  
Particle Velocity ◽  
Fish Farm ◽  
Fluid Particle ◽  
Irregular Waves ◽  
Engineering Practice ◽  
Irregular Wave ◽  
Environmental Force ◽  
The Mean ◽  
Particle Velocities ◽  
Farm System

Accurate calculation of the design mooring loads on an aquaculture fish farm mooring system is often a difficult task. The fish farm system has a large horizontal extension with variable environmental conditions across the entire structure. In addition, the drag loads on the fish nets are thought to be the governing environmental force. This means that the mean position of the fish farm is a function of the mean of the fluid particle velocity squared, where the fluid particle velocity must be taken as the sum of current and wave induced fluid particle velocities. Additional offsets will be slowly varying, where the response time will depend on the total mooring stiffness. The magnitudes depend on the height and length on wave groups in the irregular sea state. The paper presents simulations of the response of such a system to a set of combined irregular waves and current conditions. The response evolution in time is discussed as well as parameters affecting the maximum responses in the systems (displacements and loads). Finally, the resulting loads on the fish farm in irregular waves are compared to loads obtained in equivalent regular waves, as this is an often used engineering practice when analyzing the response and mooring loads of a fish farm.

scholarly journals Lagrangian Solution for an Irrotational Progressive Water Wave Propagating on a Uniform Current

2013 ◽  
Vol 30 (4) ◽  
pp. 825-845 ◽  
Author(s):  
Yang-Yih Chen ◽  
Hsuan-Shan Chen ◽  
Chu-Yu Lin ◽  
Meng-Syue Li
Keyword(s):  
Particle Velocity ◽  
Particle Motion ◽  
Particle Transport ◽  
Water Wave ◽  
Particle Trajectory ◽  
Lagrangian Solution ◽  
Transport Velocity ◽  
Motion Period ◽  
Fifth Order ◽  
Horizontal Particle

Abstract Experiments are conducted to measure the motion properties of water particle for the progressive water wave propagation in the presence of following and adverse uniform currents. The experimental data are used to validate the fifth-order Lagrangian solution from Chen and Chen. The experimental results show that the measured data of the particle motion properties such as the b line (denoted as the line connecting the positions of consecutive particles of the same b label), the particle velocity, the particle transport velocity (drift velocity), the particle trajectory, the particle motion period, and the Lagrangian mean level are in close agreement with those of the fifth-order Lagrangian solution. The study also shows that the particle label could adopt the position coordinates of the particle as if it were in still water. The motion of the b line oscillates like wave motion: its wavelength is equal to the progressive wavelength and its wave velocity obeys the Doppler effect so the sum of the velocities of the progressive wave and current, the particle motion period, the Lagrangian mean level, and the particle transport velocity less current velocity are the same as for the case of pure progressive waves. For following currents, the shape of particle trajectory depends on the horizontal particle velocity at the trajectory trough. For adverse currents, the shape of particle trajectory depends on the horizontal particle velocity at the trajectory crest. For a description of the flow motion, the Lagrangian solution could be more effective and precise than the Eulerian solution.

Factorial Analysis on the 2-D Transient Solid Velocity in Fluidized Bed Combustor

2003 ◽  
Author(s):  
Seong W. Lee ◽  
Yun Liu
Keyword(s):  
Fluidized Bed ◽  
Particle Velocity ◽  
Design Method ◽  
Factorial Analysis ◽  
Cold Model ◽  
Experimental Conditions ◽  
Image Velocimetry ◽  
Transient Velocity ◽  
Particle Velocities ◽  
Fluidized Bed Combustor

The transient solid velocity analysis in fluidized bed combustor (FBC) freeboard has been critical in the past two decades (Haidin et al 1998). The FBC cold model (6-in ID) was designed and fabricated. The solid transient velocity in FBC freeboard was measured and analyzed with the assistance of the advanced instrumentation. The laser-based Particle Image Velocimetry (PIV) was applied to the FBC cold model to visualize the transient solid velocity. A series of transient particle velocity profiles were generated for factorial analysis. In each profile, the particle velocity vectors for 100 position points were in the format of Vx and Vy. Analysis of Variance (ANOVA) was used to determine the significant factors that affect the transient particle velocities, time, and position coordinates. Then, the 1010factorial design method was used to develop a specific empirical model of transient particle velocity in FBC freeboard which was in the shape of Vx = f1(t, x, y), and Vy = f2(t, x, y). This unique factorial analysis method was proved to be very effective and practical to evaluate the experimental conditions and analyze the experimental results in FBC systems.

Effects of Variational Particle Restitution Characteristics on Turbomachinery Erosion

1993 ◽  
Author(s):  
Awatef Hamed ◽  
Timothy P. Kuhn
Keyword(s):  
Gas Turbines ◽  
Laser Doppler Velocimetry ◽  
Particle Trajectory ◽  
Particle Dynamics ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Sampling Techniques ◽  
Flow Conditions ◽  
Mean Values ◽  
Particle Velocities

This paper presents the results of an investigation to determine the effects of variational particle rebounding models on surface impacts and blade erosion patterns in gas turbines. The variance in the particle velocities after the surface impacts are modeled based on the experimental measurements using Laser Doppler Velocimetry (LDV) under varying flow conditions. The probabilistic particle trajectory computations simulate the experimental variance in the particle restitution characteristics using cumulative distribution functions and random sampling techniques. The results are presented for the particle dynamics through a gas turbine flow field and are compared to those obtained with deterministic rebound models based on experimental mean values.

scholarly journals High-Gradient Cherenkov Radiation Based on a New Dielectric-Loaded Waveguide

Particles ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 279-284
Author(s):  
Shimin Jiang ◽  
Weiwei Li ◽  
Zhigang He ◽  
Qika Jia
Keyword(s):  
Relativistic Electron ◽  
Cherenkov Radiation ◽  
High Gradient ◽  
New Type ◽  
Simulation Results

A new type of dielectric-loaded waveguide, the high-gradient dielectric-loaded waveguide (HG-DLW), where the Cherenkov radiation with a high gradient can be excited by relativistic electron, is proposed in this paper. Based on the simulation results, the process of the high-gradient Cherenkov radiation excited in the proposed structure is studied in details, and the amplitude of wakefields excited in proposed structure can be enhanced by over six times compared with that from ordinary dielectric-loaded waveguides.

Dielectrophoresis velocities response on tapered electrode profile: simulation and experimental

2019 ◽  
Vol 36 (2) ◽  
pp. 45-53
Author(s):  
Muhammad Izzuddin Abd Samad ◽  
Muhamad Ramdzan Buyong ◽  
Shyong Siow Kim ◽  
Burhanuddin Yeop Majlis
Keyword(s):  
Electric Field ◽  
Field Intensity ◽  
Particle Velocity ◽  
Applied Voltage ◽  
Electric Field Intensity ◽  
Particle Trajectory ◽  
Numerical Study ◽  
Time Interval ◽  
Content Type ◽  
Field Density

Purpose The purpose of this paper is to use a particle velocity measurement technique on a tapered microelectrode device via changes of an applied voltage, which is an enhancement of the electric field density in influencing the dipole moment particles. Polystyrene microbeads (PM) have used to determine the responses of the dielectrophoresis (DEP) voltage based on the particle velocity technique. Design/methodology/approach Analytical modelling was used to simulate the particles’ polarization and their velocity based on the Clausius–Mossotti Factor (CMF) equation. The electric field intensity and DEP forces were simulated through the COMSOL numerical study of the variation of applied voltages such as 5 V p-p, 7 V p-p and 10 V p-p. Experimentally, the particle velocity on a tapered DEP response was quantified via the particle travelling distance over a time interval through a high-speed camera adapted to a high-precision non-contact depth measuring microscope. Findings The result of the particle velocity was found to increase, and the applied voltage has enhanced the particle trajectory on the tapered microelectrode, which confirmed its dependency on the electric field intensity at the top and bottom edges of the electrode. A higher magnitude of particle levitation was recorded with the highest particle velocity of 11.19 ± 4.43 µm/s at 1 MHz on 10 V p-p, compared to the lowest particle velocity with 0.62 ± 0.11 µm/s at 10 kHz on 7 V p-p. Practical implications This research can be applied for high throughout sensitivity and selectivity of particle manipulation in isolating and concentrating biological fluid for biomedical implications. Originality/value The comprehensive manipulation method based on the changes of the electrical potential of the tapered electrode was able to quantify the magnitude of the particle trajectory in accordance with the strong electric field density.

Effects of Variational Particle Restitution Characteristics on Turbomachinery Erosion

1995 ◽  
Vol 117 (3) ◽  
pp. 432-440 ◽  
Author(s):  
A. Hamed ◽  
T. P. Kuhn
Keyword(s):  
Gas Turbines ◽  
Laser Doppler Velocimetry ◽  
Particle Trajectory ◽  
Particle Dynamics ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Sampling Techniques ◽  
Flow Conditions ◽  
Mean Values ◽  
Particle Velocities

This paper presents the results of an investigation to determine the effects of variational particle rebounding models on surface impacts and blade erosion patterns in gas turbines. The variance in the particle velocities after the surface impacts are modeled based on the experimental measurements using Laser-Doppler Velocimetry (LDV) under varying flow conditions. The probabilistic particle trajectory computations simulate the experimental variance in the particle restitution characteristics using cumulative distribution functions and random sampling techniques. The results are presented for the particle dynamics through a gas turbine flow field and are compared to those obtained with deterministic rebound models based on experimental mean values.

3D Numerical Simulation and PEPT Experimental Investigation of Pressurized Gas-Solid Fluidized Bed Hydrodynamic

2009 ◽  
Author(s):  
P. Fede ◽  
G. Moula ◽  
A. Ingram ◽  
T. Dumas ◽  
O. Simonin
Keyword(s):  
Numerical Model ◽  
Fluidized Bed ◽  
Particle Velocity ◽  
Particle Trajectory ◽  
Wall Region ◽  
3 Dimensional ◽  
The Core ◽  
Numerical Predictions ◽  
Model Predictions ◽  
Good Agreement

The present paper is dedicated to numerical and experimental study of the hydrodynamic of a non-reactive isothermal pressurized fluidized bed. Experimental data have been obtained using PEPT technique allowing to track a particle trajectory inside a dense fluidized bed. A specific post-processing approach has been developed to compute the Eulerian time-averaged particle velocity field. The comparison with 3-dimensional numerical model predictions shows a good agreement in the core of the fluidized bed. In contrast, in the near wall region the numerical model overestimate the downward particle velocity. The modification of particle phase wall boundary condition improves the numerical predictions.

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