scholarly journals Nonlinear processes in the bunched electron beams of high-power klystrons and the limits of analytical and one-dimensional numerical models applicability for their analysis.

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
V.Y. Rodyakin ◽  
◽  
V.M. Pikunov ◽  
V.N. Aksenov ◽  
◽  
...  
Keyword(s):  
Electron Beam ◽  
High Power ◽  
Numerical Models ◽  
Nonlinear Effects ◽  
Analytical Models ◽  
Modulation Amplitude ◽  
Two Dimensional ◽  
One Dimensional ◽  
Charge Parameter ◽  
Program Data

We present the results of a comparative theoretical analysis of the electron beam bunching in a single-stage klystron amplifier using analytical models, a one-dimensional disk program, and a two-dimensional program. Data on the influence of various one-dimensional and two-dimensional nonlinear effects on the efficiency of electron beam bunching at different values of the space charge parameter and the modulation amplitude are presented. The limits of applicability of analytical and one-dimensional numerical models for electron beam bunching analysis in high-power klystron amplifiers are found.

scholarly journals Plasmonic kinks and walking solitons in nonlinear lattices of metal nanoparticles

2014 ◽  
Vol 372 (2027) ◽  
pp. 20140010 ◽  
Author(s):  
Roman E. Noskov ◽  
Daria A. Smirnova ◽  
Yuri S. Kivshar
Keyword(s):  
External Field ◽  
Metallic Nanoparticles ◽  
Nonlinear Effects ◽  
Two Dimensional ◽  
Driving Field ◽  
One Dimensional ◽  
Structure And Dynamics ◽  
Nonlinear Lattices ◽  
The Impact ◽  
External Driving

We study nonlinear effects in one-dimensional (1D) arrays and two-dimensional (2D) lattices composed of metallic nanoparticles with the nonlinear Kerr-like response and an external driving field. We demonstrate the existence of families of moving solitons in 1D arrays and characterize their properties such as an average drifting velocity. We also analyse the impact of varying external field intensity and frequency on the structure and dynamics of kinks in 2D lattices. In particular, we identify the kinks with positive, negative and zero velocity as well as breathing kinks with a self-oscillating profile.

Fluid mechanics of the cochlea. Part 1

1972 ◽  
Vol 51 (3) ◽  
pp. 497-512 ◽  
Author(s):  
M. B. Lesser ◽  
D. A. Berkley
Keyword(s):  
Fluid Mechanics ◽  
Potential Flow ◽  
Analytical Study ◽  
Nonlinear Effects ◽  
Two Dimensional ◽  
One Dimensional ◽  
Flow Models ◽  
Place Theory ◽  
Mechanical Models ◽  
Potential Flow Model

The physiology of the cochlea (part of the inner ear) is briefly examined in conjunction with a description of the ‘place’ theory of hearing. The role played fluid motions is seen to be of importance, and some attempts to bring fluid mechanics into a theory of hearing are reviewed. Following some general fluid-mechanical considerations a potential flow model of the cochlea is examined in some detail. A basic difference between this and previous investigations is that here we treat anenclosedtwo-dimensional cavity as opposed to one-dimensional and open two-dimensional models studied earlier. Also the two time-scale aspect of the problem, as a possible explanation for nonlinear effects in hearing, has not previously been considered. Thus observations on mechanical models indicate that potential flow models are applicable for times of the same scale as the frequency of the driving acoustic inputs. For larger time scales mechanical models show streaming motions which dominate the qualitative flow picture. The analytical study of these effects is left for a future paper.

scholarly journals Reflection of waveguided X-rays in two-dimensional nanostructures

2002 ◽  
Vol 35 (4) ◽  
pp. 430-433 ◽  
Author(s):  
Franz Pfeiffer ◽  
Tim Salditt ◽  
Christian David
Keyword(s):  
Thin Film ◽  
Electron Beam ◽  
Electron Beam Lithography ◽  
Waveguide Mode ◽  
Waveguide Structure ◽  
X Rays ◽  
Two Dimensional ◽  
One Dimensional ◽  
X Ray ◽  
Simultaneous Excitation

The internal reflection of an excited X-ray waveguide mode in a synthetic nanostructure, defined by electron-beam lithography, has been measured. In this device, the X-ray beam is first coupled into a conventional vertical thin-film waveguide structure and then reflected laterally at the quasi-one-dimensional edge of the waveguiding layer. The reflectivity of the quasi-one-dimensional interface has been recorded under simultaneous excitation of the (vertical) waveguide mode. The experiment constitutes an important step towards the production of a coherent nanometre-sized X-ray point source by two-dimensionally defined waveguide structures.

Ship Motions From Unsteady Maneuvering in Two-Dimensional Waves: Part II—Analysis of Data

2011 ◽  
Author(s):  
Joseph T. Klamo ◽  
Ray-Qing Lin
Keyword(s):  
Wave Field ◽  
Degrees Of Freedom ◽  
Nonlinear Effects ◽  
Ship Motions ◽  
Two Dimensional ◽  
Linear Superposition ◽  
One Dimensional ◽  
Model Response ◽  
Experimental Laboratory ◽  
Dimensional Wave

An experimental test has been conducted to measure the six degrees-of-freedom motions of a remote-controlled model attempting to hold heading while at forward speed in a two-dimensional wave field. During testing, the two underlying components of the wave field were always orthogonal to each other but various relative headings of the model to the dominant wave were explored. Of particular interest is understanding the nonlinear effects of the two distinct underlying wave encounter frequencies on the model response and the severity to which it causes the response in the two-dimensional wave field to differ from the linear summation of responses from equivalent one-dimensional waves. Since the experimental data contains the full wave-wave and wave-ship interactions of the two-dimensional wave field, we will use numerical results from the Digital, Self-consistent Ship Experimental Laboratory (DiSSEL) to generate the necessary one-dimensional wave results. This allows us to compare the predicted ship response motions from linear superposition of two one-dimensional wave field responses to the measured motions in a two-dimensional wave field for various relative wave heading combinations. It will be shown that for waves forward of beam, the predicted pitch results from superposition are fairly accurate while the roll prediction is not. However, for waves aft of beam, the motion predictions from linear superposition of pitch and roll are both poor. In such aft of beam cases, the disagreement can be quite large due to deviations in the ship heading caused by drift forces.

scholarly journals On the Kinematics of Solar Mirrors Using Massively Parallel Binary Actuation

2010 ◽  
Author(s):  
Seung J. Lee ◽  
Amy M. Bilton ◽  
Steven Dubowsky
Keyword(s):  
Experimental Studies ◽  
Analytical Models ◽  
Massively Parallel ◽  
Thermal Gradients ◽  
Two Dimensional ◽  
Principle Of Superposition ◽  
Element Analysis ◽  
Solar Concentrators ◽  
One Dimensional ◽  
Binary Actuators

Precision mirrors are required for effective solar energy collectors. Manufacturing such mirrors and making them robust to disturbances such as thermal gradients is expensive. In this paper, the use of parallel binary actuation to control the shape of mirrors for solar concentrators is explored. The approach embeds binary actuators in a compliant mirror substructure. Actuators are deployed in a specified pattern to correct the mirror shape. The analysis for binary-actuated compliant mirror structures is presented. Analytical models are developed for one-dimensional and two-dimensional compliant structures with embedded binary actuators. These analytical models are validated using finite element analysis and experimental studies. The models and experiments demonstrate the capabilities of binary actuated mirrors. System workspace is explored, the principle of superposition required for their control is demonstrated, as is the mirror ability to correct its figure.

The simulation of plasma double-layer structures in two dimensions

1983 ◽  
Vol 29 (1) ◽  
pp. 45-84 ◽  
Author(s):  
Joseph E. Borovsky ◽  
Glenn Joyce
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Double Layer ◽  
Ion Beam ◽  
Two Dimensions ◽  
Distribution Functions ◽  
Double Layers ◽  
Two Dimensional ◽  
One Dimensional ◽  
Electron Cyclotron Waves

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2½-dimensional particle-in-cell method, periodic in one direction and bounded by reservoirs of Maxwellian plasma in the other. The investigation of planar double layers indicates that these one-dimensional potential structures are susceptible to periodic disruption by plasma instabilities. A slight increase in the double-layer thickness with an increase in its obliqueness to the magnetic field is observed. It is noted that weak magnetization results in the double-layer electric-field alignment of particles accelerated by these potential structures and that strong magnetization results in their magnetic-field alignment. Electron-beam-excited electrostatic electron cyclotron waves and ion-beam-driven electrostatic turbulence are present in the plasmas adjacent to the double layers. The numerical simulations of spatially periodic two-dimensional double layers also exhibit cyclical instability. A morphological invariance in two-dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Ion-beam-driven electrostatic turbulence and electron-beam-driven plasma waves are again detected. A simplified one-dimensional model of oblique plasma double layers, using water-bag velocity distribution functions, is presented in an appendix.

scholarly journals Monotonic and Fatigue Behavior of EBM Manufactured Ti-6Al-4V Solid Samples: Experimental, Analytical and Numerical Investigations

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4642 ◽  
Author(s):  
Wiebke Radlof ◽  
Christopher Benz ◽  
Horst Heyer ◽  
Manuela Sander
Keyword(s):  
Electron Beam ◽  
Plastic Material ◽  
Numerical Models ◽  
Fatigue Behavior ◽  
Damage Model ◽  
Material Model ◽  
Tensile Tests ◽  
Product Development Process ◽  
Analytical Models ◽  
Solid Samples

The present study aims to carry out an experimental, analytical and numerical investigation of the monotonic and fatigue performance of electron beam melted Ti-6Al-4V structures. Therefore, tensile tests, multiple step tests and strain-life tests were performed on machined EBM Ti-6Al-4V solid samples. An elastic-plastic material model in combination with a numerical damage model was examined according to the experimental tensile tests. Analytical models proposed by Ramberg and Osgood, as well as Coffin and Manson were obtained to describe the cyclic stress-strain curves and strain-life curves, respectively. The fracture surfaces of the tested samples and the influence of different build directions were analyzed. A prediction of the static and fatigue material properties is of particular importance, e.g., for the safe application of additively manufactured load-bearing implant structures. Based on the determined analytical and numerical models, the material and product behavior of complex electron beam melted structures under cyclic loading and fatigue life determination can be investigated in the early stages of the product development process.

scholarly journals Intrinsic Topological Magnons In Arrays of Magnetic Dipoles

2021 ◽  
Author(s):  
Paula Mellado
Keyword(s):  
Easy Axis ◽  
Magnetic System ◽  
Two Dimensions ◽  
Modulation Amplitude ◽  
Two Dimensional ◽  
Dipolar Interactions ◽  
Magnetic Dipoles ◽  
One Dimensional ◽  
Chern Numbers ◽  
Magnon Spectrum

Abstract We study a simple magnetic system composed of periodically modulated magnetic dipoles with an easy axis. Upon adjusting the modulation amplitude alone, chains and two-dimensional stacked chains exhibit a rich magnon spectrum where frequency gaps and magnon speeds are easily manipulable. The blend of anisotropy due to dipolar interactions between magnets and geometrical modulation induces a magnetic phase with fractional Zak number in infinite chains and end states in open one-dimensional systems. In two dimensions it gives rise to topological modes at the edges of stripes. Tuning the amplitude in two-dimensional lattices causes a band touching, which triggers the exchange of the Chern numbers of the volume bands and switches the sign of the thermal conductivity.

Semi-Analytical Models of Field-Effect Transistors with Low-Dimensional Channels

2011 ◽  
Vol 276 ◽  
pp. 51-57
Author(s):  
A. Kohmyakov ◽  
V. Vyurkov
Keyword(s):  
Field Effect ◽  
Potential Distribution ◽  
Field Effect Transistors ◽  
Silicon On Insulator ◽  
Analytical Models ◽  
Double Gate ◽  
Two Dimensional ◽  
One Dimensional ◽  
The Poisson Equation ◽  
Low Dimensional

A semi-analytical model which is applicable to description of ballistic field-effect transistors with low-dimensional channels is proposed. For instance, such transistors can be manufactured on a “silicon-on-insulator” wafer. The model accounts for single-gate and double-gate structures with one-dimensional and two-dimensional channels. It differently describes the regimes of a transistor above threshold and below threshold. The first implies an essential influence of charge inside the channel on a potential distribution; the second supposes a negligible charge inside the channel. Both approaches are mainly based upon an approximate solution of the Poisson equation.

scholarly journals One and Two-Dimensional Hydraulic Simulation of a Reach in Al-Gharraf River

2020 ◽  
Vol 26 (7) ◽  
pp. 28-44
Author(s):  
Mariam H. Daham ◽  
Basim Sh. Abed
Keyword(s):  
Numerical Models ◽  
Two Dimensional ◽  
Hydraulic Characteristics ◽  
Dimensional Model ◽  
Hydraulic Simulation ◽  
One Dimensional ◽  
Two Dimensional Model ◽  
Average Water ◽  
The One ◽  
Manning Roughness

        One and two-dimensional hydraulic models simulations are important to specify the hydraulic characteristics of unsteady flow in Al-Gharraf River in order to define the locations that facing problems and suggesting the necessary treatments. The reach in the present study is 58200m long and lies between Kut and Hai Cities. Both numerical models were simulated using HEC-RAS software, 5.0.4, with flow rates ranging from 100 to 350 m3/s. Multi-scenarios of gates openings of Hai Regulator were applied. While the openings of Al-Gharraf Head Regulator were ranged between 60cm to fully opened. The suitable manning roughness for the unsteady state was 0.025. The obtained results show that the average velocities for the one-dimensional model were ranged between 0.36 and 0.5 m/s,  and the average water surface elevations range between 15.14 m and 17.84 m. While these values ranged between 0.25 and 0.44 m/s and 14.125 and 18.82 m respectively for the two-dimensional model. The simulation results of the two-dimensional model were more accurate than their corresponding one-dimensional model, due to more agreement of these values with measured values, which achieved minimum values of the root mean square error and the determination coefficient.

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