Breathing dynamics of a trapped impurity in a dipolar Bose gas

2014 ◽  
Vol 28 (22) ◽  
pp. 1450185 ◽  
Author(s):  
Fang-Qi Hu ◽  
Ju-Kui Xue
Keyword(s):  
Variational Approach ◽  
Radial Direction ◽  
Axial Direction ◽  
Critical Value ◽  
Bose Gas ◽  
Spherically Symmetric ◽  
Significant Modification ◽  
Strongly Coupled ◽  
Effective Potentials ◽  
Dipole Interactions

With the consideration of impurity-bosons coupling and dipole–dipole interactions (DDI), we study the breathing dynamics of a harmonically trapped impurity interacting with a separately trapped background of dipolar Bose gas. By using the variational approach, the breathing equations, the breathing frequencies and the effective potentials governing the breathing dynamics of the impurity in dipolar gas are obtained. The effects of DDI, impurity-bosons interaction and external trapping potentials on breathing dynamics of impurity are discussed. We find that, because of the anisotropic and long-range characters of DDI, the effects of DDI, impurity-bosons interaction and external trapping potentials on breathing dynamics of impurity are strongly coupled. DDI has significant modification on dynamics, which depends on the external trapping potentials. For spherically symmetric external trapping, DDI makes the impurity more cigar-shaped along axial direction and the breathing oscillation in radial direction is suppressed by DDI. However, the effect of DDI on the breathing dynamics is weakened for cigar-shaped external trapping. Interestingly, for strong external pancake-shaped trapping, the symmetries of the breathing dynamics with respect to attractive and repulsive impurity-bosons coupling recover. Especially, for some critical value of impurity-bosons coupling, the breathing dynamics undergo a sudden quench.

Dynamic Behavior of the Spherical Squeeze-Film Hybrid Bearing

1969 ◽  
Vol 91 (1) ◽  
pp. 149-160
Author(s):  
C. H. T. Pan ◽  
T. Chiang
Keyword(s):  
Radial Direction ◽  
Axial Direction ◽  
Critical Value ◽  
Rotational Frequency ◽  
Squeeze Film ◽  
Small Vibration ◽  
Hybrid Bearing ◽  
The Stability ◽  
Squeeze Number ◽  
Perturbation Solutions

The stability and vibration response of a spherical squeeze-film hybrid bearing were analyzed theoretically. Since the squeeze frequency is typically much higher than the vibration frequency, the asymptotic analysis for large squeeze number can be applied here. Perturbation solutions about the radially concentric position were obtained for small vibration amplitudes and small radial displacement. There is no limitation, however, in the values of vibration number (so long as it is small in comparison with the squeeze number), compressibility number, axial displacement ratio, and excursion ratio. Dynamic bearing reactions were computed based on the perturbation solutions. Results indicate that a spherical squeeze-film bearing is always stable in the axial direction. In the radial direction, however, instability about the radially concentric position is possible when there is journal rotation, the frequency of instability is exactly one half of the rotational frequency; the system would be stable if the mass is kept below the critical value. The analysis can be readily extended to compute the response to vibratory excitation in either the axial or the radial direction.

Analysis of Vibration Caused by Electromagnetic Force on Stator End-Winding of Large Dry Submersible Motor

2013 ◽  
Vol 416-417 ◽  
pp. 428-432
Author(s):  
Li Shan ◽  
Xiao Wei Cheng ◽  
Yong Fang ◽  
Xiao Hua Bao
Keyword(s):  
Electromagnetic Field ◽  
Steady State ◽  
Transition State ◽  
Electromagnetic Force ◽  
Radial Displacement ◽  
Radial Direction ◽  
Axial Direction ◽  
Axial Displacement ◽  
Force Density ◽  
Submersible Motor

This paper investigates the vibration which caused by electromagnetic on the stator end-winding of the large dry submersible motor. Firstly, the electromagnetic field which included transition state and steady state is researched by 3-D FEM. Secondly, the electromagnetic force which lead to vibrations of end-winding is calculated by numerical method, it can be obtained that where endured the largest force density along the slant part of end-winding. Finally, the radial displacement and the axial displacement of the slant part which caused by vibrations is studied, the analysis results show that the axial displacement is larger than the amplitude of radial displacement. It indicates that the slant part of end-winding will be more easily damaged at axial direction than radial direction.

scholarly journals New Solution of a Spherically Symmetric Static Problem of General Relativity

2017 ◽  
Vol 9 (5) ◽  
pp. 29
Author(s):  
Valery Vasiliev
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Classical Solution ◽  
Critical Radius ◽  
Static Problem ◽  
Critical Value ◽  
Relativity Theory ◽  
Spherically Symmetric ◽  
General Relativity Theory ◽  
Gravitational Radius

The paper is concerned with the spherically symmetric static problem of the General Relativity Theory. The classical solution of this problem found in 1916 by K. Schwarzschild for a particular metric form results in singular space metric coefficient and provides the basis of the objects referred to as Black Holes. A more general metric form applied in the paper allows us to obtain the solution which is not singular. The critical radius of the fluid sphere, following from this solution does not coincide with the traditional gravitational radius. For the spheres with radii that are less than the critical value, the solution of GRT problem does not exist.

Influence of Structure of Electrode Array on Logging. The Resistivity Logging Response through Casing of Structure of Electrode Array

2014 ◽  
Vol 1006-1007 ◽  
pp. 990-993
Author(s):  
An Ling Wang ◽  
Fu Ping Liu
Keyword(s):  
Radial Direction ◽  
Recurrence Formula ◽  
Electrode Array ◽  
Axial Direction ◽  
Formation Model ◽  
Line Equation ◽  
Metal Casing ◽  
Resistivity Logging ◽  
Important Significance ◽  
Computing Speed

Because difference of formation model affects the potential distribution on the metal casing, the resistivity logging response can be obtained through casing by measuring the potentials on the metal casing. In fact, the logging responses are the comprehension effects of complex formation and metal casing, so that in the coefficients of transmission line equation (TLE), we should consider the effects of formation model in radial-direction. In the following, for the formation taking on six-layer in axial-direction, and step in radial-direction, the resistivity logging responses through casing are researched and discussed, and given the recurrence formula to compute potential. Draw the curve of the resistivity logging response through casing of six-layer formations. The conductivity of formation is computed is very approximating to that of formation model. The computing examples also show that this method has a fast computing speed (the run time of computing example is less than 1s). For analysis the logging response of six-layers and block formations, and the design of logging instruments, the research is important significance and useful.

Mechanical Model of Non-Magnetic Particles Centrifugal Separation in Magnetic Fluid

2013 ◽  
Vol 820 ◽  
pp. 225-228
Author(s):  
Tong Li ◽  
Jing Tao Wei ◽  
Ji Li
Keyword(s):  
Centrifugal Force ◽  
Magnetic Fluid ◽  
Mechanical Model ◽  
Radial Direction ◽  
Magnetic Particles ◽  
Axial Direction ◽  
Separation Mechanism ◽  
Centrifugal Separation

It is difficult to sort fine non-magnetic particles only by the buoyancy of magnetic fluid. Therefore, based on the magneto hydrostatic separation, the centrifugal separation under the condition of centrifugal force would be an effective method to improve the efficiency. By establishing the mechanical model of centrifugal separation in magnetic fluid, this paper analyzes the kinematical equations of non-magnetic particles in three directionstangential direction, radial direction, and axial direction, and then theoretically explores the separation mechanism of this method.

USE OF SOLID STATE NUCLEAR TRACK DETECTORS CR-39 TO STUDY CHARGED PARTICLES EMISSION FROM A 3 kJ PLASMA FOCUS

1995 ◽  
Vol 09 (16) ◽  
pp. 1033-1037
Author(s):  
M. ZAKAULLAH ◽  
IMTIAZ AHMAD ◽  
KHAIRUR REHMAN ◽  
G. MURTAZA
Keyword(s):  
Charged Particle ◽  
Solid State ◽  
Plasma Focus ◽  
Radial Direction ◽  
Particle Flux ◽  
Charged Particles ◽  
Axial Direction ◽  
Low Energy ◽  
Nuclear Track Detectors

The CR-39 solid state nuclear track detectors are employed to investigate the fluence anisotropy of charged particles (protons, deuterons and tritons) emitted from the focus region of a low energy Mather-type plasma focus energized by a single 32 μF, 15 kV (3.6 kJ) capacitor. The charged particle flux is the highest in the axial direction, and decreases towards the radial direction. The radial charged particles flux is six times smaller than the flux in the axial direction.

Ground state of the strongly coupled, charged Bose gas

1978 ◽  
Vol 18 (3) ◽  
pp. 1282-1290 ◽  
Author(s):  
Jean-Pierre Hansen ◽  
Redha Mazighi
Keyword(s):  
Ground State ◽  
Bose Gas ◽  
Strongly Coupled

scholarly journals HOLOGRAPHIC SUPERCONDUCTOR FOR A LIFSHITZ FIXED POINT

2011 ◽  
Vol 26 (26) ◽  
pp. 4617-4631 ◽  
Author(s):  
SANG-JIN SIN ◽  
SHAN-SHAN XU ◽  
YANG ZHOU
Keyword(s):  
Fixed Point ◽  
Recent Work ◽  
Finite Temperature ◽  
Coupled System ◽  
Temperature Limit ◽  
Critical Value ◽  
Higgs Model ◽  
Zero Temperature ◽  
Holographic Superconductor ◽  
Strongly Coupled

We consider the gravity dual of strongly coupled system at a Lifshitz-fixed point and finite temperature, which was constructed in a recent work arXiv:0909.0263. We construct an Abelian–Higgs model in that background and calculate condensation and conductivity using holographic techniques. We find that condensation happens and DC conductivity blows up when temperature turns below a critical value. We also study the zero temperature limit of strongly coupled system at the Lifshitz-fixed point.

Pitting Corrosion Diagnosis of Bearing Based on Power Cepstrum and Histogram

2012 ◽  
Vol 512-515 ◽  
pp. 1672-1676 ◽  
Author(s):  
Shu Fang ◽  
De Liang Li ◽  
Li Tao Liu ◽  
Zhen Wei Zhang
Keyword(s):  
Pitting Corrosion ◽  
Vibration Amplitude ◽  
Radial Direction ◽  
Impact Force ◽  
Axial Direction ◽  
High Impact ◽  
New Method ◽  
Outer Ring ◽  
Heavy Load ◽  
Bearing Race

The axle assembly of fire robot need endure both heavy load and high impact force, and the pitting corrosion in the bearing race become a commom fault. In this paper, the vibration of bearing both in the inner ring and outer ring was analyzed, the characteristics of bearing with pitting corrosion were also analyzed, and based on those characteristics a new method for pitting corrosion diagnosis were proposed, in this method the power cepstrum in the axial direction and histogram of the vibration amplitude in the radial direction were used for detecting the pitting corrosion of bearing, and experiments results proved the practicability and effectiveness of this method.

scholarly journals Transient Modelling of Rotating and Stationary Cylindrical Heat Pipes: An Engineering Model

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3458 ◽  
Author(s):  
Metin Celik ◽  
Geert Paulussen ◽  
Dennis van Erp ◽  
Wiebren de Jong ◽  
Bendiks Boe
Keyword(s):  
Heat Pipe ◽  
Radial Direction ◽  
Computational Cost ◽  
Heat Pipes ◽  
Transient Behavior ◽  
Axial Direction ◽  
Engineering Model ◽  
Average Deviation ◽  
Lumped Parameter ◽  
Lumped Parameter Models

Rotating wickless and stationary capillary cylindrical heat pipes are widely used heat transfer devices. Transient behavior of such heat pipes has been investigated numerically with computational fluid dynamics and lumped parameter models. In this paper, the advantages of both methods are combined into a novel engineering model that is low in computational cost but still accurate and rich in the details it provides. The model describes the interior dynamics of the heat pipe with a 2D representation of a cylindrical heat pipe. Liquid and vapor volumes are coarsely meshed in the axial direction. The cells are allowed to change in size in the radial direction during simulation. This allows for tracking the liquid/vapor interface without having to implement fine meshing. The model includes the equations for mass, momentum and energy and is applicable to both rotating and stationary heat pipes. The predictions of the model are validated with other experimental, numerical, and analytical works having an average deviation of less than 4%. The effects of various parameters on the system are explored. The presented model is suitable for the simulation of heat pipe systems in which both the level of detail and the computational cost are crucial factors.

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