THE STUDY OF SCATTERING He FROM Cu(110) WITH A NEW MODEL POTENTIAL

1991 ◽  
Vol 05 (27) ◽  
pp. 1795-1801 ◽  
Author(s):  
F. GÖĞTAS
Keyword(s):  
Incident Angle ◽  
Pair Potential ◽  
Model Potential ◽  
Experimental Results ◽  
New Model ◽  
Good Agreement

The dependence of specular and diffracted probabilities on the incident angle and energy was investigated for He+Cu(110). A new empirical pair potential used in this study gives a good agreement with experimental results.

He DIFFRACTION FROM Ag(110) SURFACE

1992 ◽  
Vol 06 (01) ◽  
pp. 109-123
Author(s):  
M. ARTUNÇ ◽  
M. CEYLAN ◽  
N. KOLSUZ
Keyword(s):  
Incident Energy ◽  
Incident Angle ◽  
Van Der Waals ◽  
Experimental Results ◽  
Coupling Method ◽  
Close Coupling ◽  
Softness Parameter ◽  
Well Depth ◽  
Good Agreement ◽  
Mie Potential

Using the exact close-coupling method we have investigated the diffraction intensities of He atoms from a Ag(110) surface. He-Ag(110) interaction is represented by a corrugated Mie potential. In our calculations we have used three different well depths D. Diffraction intensities were calculated for x = <001> direction. The softness parameter β is optimized for a given incident energy Ei and incident angle θi so as to reproduce the experimental results. Using well depth D and van der Waals constant C3 for six He-metal (Al, Ni, Cu, Ag, Pt, Au) systems we have obtained a relation, D = 0.070C3 − 9.006, between parameters D and C3. Our results are in good agreement with experimental observations.

Modelling and Analysis of Capacitive Effects in a High Frequency Coaxial Transformer

2012 ◽  
Vol 466-467 ◽  
pp. 607-611
Author(s):  
Xiao Guang Yang
Keyword(s):  
Energy Storage ◽  
Electromagnetic Interference ◽  
High Frequency ◽  
Electric Energy ◽  
Experimental Results ◽  
Voltage Distribution ◽  
New Model ◽  
Electric Energy Storage ◽  
Proposed Model ◽  
Good Agreement

A new model is proposed for analyzing the capacitive effects in a newly developed high frequency coaxial transformer (HFCT). The proposed model can describe both the electric energy storage and common-mode (CM) electromagnetic interference (EMI) noise behaviors of a transformer, considering the voltage distribution in the HFCT windings. To determine the parameters of the model, a parasitic capacitance network is developed to describe the HFCT’s real winding’s structure, and the distributed parasitic capacitances of the network are evaluated using FEM based on the theory of capacitances in a multi-conductor system. The calculated inter-capacitance of the HFCT is in good agreement with the experimental results.

Modeling and Dynamic Characteristic of a Pneumatic Solenoid Valve

2011 ◽  
Vol 383-390 ◽  
pp. 7369-7374
Author(s):  
Xiao Wang Pan ◽  
Min Lin ◽  
Bin Guo ◽  
Yi Lu
Keyword(s):  
Dynamic Characteristic ◽  
Solenoid Valve ◽  
Experimental Results ◽  
New Method ◽  
New Model ◽  
Pressure Time ◽  
Simulation Results ◽  
Opening And Closing ◽  
Good Agreement

A new method, obtaining the pressure-time relations during air inflation and deflation process, is proposed to research the dynamic characteristic of a pneumatic solenoid valve. The current, magnetism, mechanical and air subsystems of the valve are investigated. In order to experimentally verify the advantage of the new model, two models are compared. Simulation results show, the opening and closing reversal times of the model without air subsystem are 29.6ms and 30.7ms. The new model’s reversal times are 31.8ms and 36.1ms. 32.5ms and 35.3ms are the results by experiments. The experimental results show very good agreement with the new model.

COMPARISON OF PRISM-BASED OPTICAL PROBES FOR LIQUID MONITORING

2010 ◽  
Vol 24 (11) ◽  
pp. 1111-1126
Author(s):  
H. GOLNABI ◽  
M. RAZANI
Keyword(s):  
Incident Angle ◽  
Experimental Results ◽  
Beam Divergence ◽  
Experimental Measurements ◽  
Optical Probes ◽  
Theoretical Formulation ◽  
Effective Application ◽  
Theoretical Investigations ◽  
Emergent Intensity ◽  
Good Agreement

In this article, two possible applications of prism-based probes for liquid-switching, level-sensing, and as a refractometer are described. Theoretical formulation is developed for the emergent intensity for each system and possible range of operation for each system is reported. By comparing the theoretical investigations, some hints are given in optimum usage of prism in each case. Variation of the beam divergence, incident angle, and prism glass index are major parameters that are considered in this investigation. The obtained results are compared with some available experimental results and practical points concerning the effective application of each geometry is reported. Theoretical expressions developed here are in good agreement with the experimental measurements.

Multislice calculations of RHEED patterns from vicinal Si (001)

1993 ◽  
Vol 51 ◽  
pp. 1000-1001
Author(s):  
Scott Lordi
Keyword(s):  
Misorientation Angle ◽  
Incident Angle ◽  
Incident Beam ◽  
Experimental Results ◽  
Bragg Condition ◽  
Vicinal Surfaces ◽  
Kinematic Theory ◽  
Step Edges

Vicinal Si (001) surfaces are interesting because they are good substrates for the growth of III-V semiconductors. Spots in RHEED patterns from vicinal surfaces are split due to scattering from ordered step arrays and this splitting can be used to determine the misorientation angle, using kinematic arguments. Kinematic theory is generally regarded to be inadequate for the calculation of RHEED intensities; however, only a few dynamical RHEED simulations have been attempted for vicinal surfaces. The multislice formulation of Cowley and Moodie with a recently developed edge patching method was used to calculate RHEED patterns from vicinal Si (001) surfaces. The calculated patterns are qualitatively similar to published experimental results and the positions of the split spots quantitatively agree with kinematic calculations.RHEED patterns were calculated for unreconstructed (bulk terminated) Si (001) surfaces misoriented towards [110] ,with an energy of 15 keV, at an incident angle of 36.63 mrad ([004] bragg condition), and a beam azimuth of [110] (perpendicular to the step edges) and the incident beam pointed down the step staircase.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals The Stationary Concentrated Vortex Model

Climate ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 39
Author(s):  
Oleg Onishchenko ◽  
Viktor Fedun ◽  
Wendell Horton ◽  
Oleg Pokhotelov ◽  
Natalia Astafieva ◽  
...  
Keyword(s):  
Vortex Structure ◽  
Radial Direction ◽  
Symmetry Axis ◽  
Outer Part ◽  
Vertical Direction ◽  
Axially Symmetric ◽  
New Model ◽  
Vortex Model ◽  
Axis Of Symmetry ◽  
Good Agreement

A new model of an axially-symmetric stationary concentrated vortex for an inviscid incompressible flow is presented as an exact solution of the Euler equations. In this new model, the vortex is exponentially localised, not only in the radial direction, but also in height. This new model of stationary concentrated vortex arises when the radial flow, which concentrates vorticity in a narrow column around the axis of symmetry, is balanced by vortex advection along the symmetry axis. Unlike previous models, vortex velocity, vorticity and pressure are characterised not only by a characteristic vortex radius, but also by a characteristic vortex height. The vortex structure in the radial direction has two distinct regions defined by the internal and external parts: in the inner part the vortex flow is directed upward, and in the outer part it is downward. The vortex structure in the vertical direction can be divided into the bottom and top regions. At the bottom of the vortex the flow is centripetal and at the top it is centrifugal. Furthermore, at the top of the vortex the previously ascending fluid starts to descend. It is shown that this new model of a vortex is in good agreement with the results of field observations of dust vortices in the Earth’s atmosphere.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

Simulation of Sphere’s Motion Induced by Shock Waves

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Dan Igra ◽  
Ozer Igra ◽  
Lazhar Houas ◽  
Georges Jourdan
Keyword(s):  
Shock Waves ◽  
Drag Coefficient ◽  
Drag Force ◽  
Stationary Flow ◽  
Experimental Results ◽  
Experimental Findings ◽  
Sphere Drag ◽  
Simulation Scheme ◽  
Good Agreement

Simulations of experimental results appearing in Jourdan et al. (2007, “Drag Coefficient of a Sphere in a Non-Stationary Flow: New Results,”Proc. R. Soc. London, Ser. A, 463, pp. 3323–3345) regarding acceleration of a sphere by the postshock flow were conducted in order to find the contribution of the various parameters affecting the sphere drag force. Based on the good agreement found between present simulations and experimental findings, it is concluded that the proposed simulation scheme could safely be used for evaluating the sphere’s motion in the postshock flow.

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