Convergence of a cylindrical liquid shell and the formation of a bore in a rotating fluid

1999 ◽  
Vol 400 ◽  
pp. 355-374
Author(s):  
V. K. KEDRINSKII ◽  
V. V. NIKULIN
Keyword(s):  
Cylindrical Cavity ◽  
Experimental Studies ◽  
Discontinuous Solution ◽  
Rotating Fluid ◽  
Rotationally Symmetric ◽  
Basic Parameters ◽  
Hollow Vortex ◽  
Long Wave Approximation ◽  
Theoretical Results ◽  
Unbounded Fluid

This paper presents the results of experimental studies of a collapsing cylindrical cavity (the convergence of a liquid shell) in a rotating fluid as well as the formation and propagation of a jump (bore) at the interface. The basic parameters of the liquid shell dynamics for a pulsed one-dimensional load are estimated using the equation of cylindrical cavity pulsation in an unbounded fluid. The theoretical model of a rotationally symmetric hydraulic jump moving along the free surface of a hollow vortex is constructed. The jump is simulated by a discontinuous solution of the equations in the long-wave approximation for tornado-like and hollow vortices. For comparison with the experimental data, basic theoretical results are obtained for flows in a hollow vortex with constant circulation and axial velocity varying along the radius of the rotating liquid shell.

Study of a Vibratory Feeder with Repulsive Surface Which Has Directional Characteristic

1980 ◽  
Vol 102 (1) ◽  
pp. 94-101 ◽  
Author(s):  
S. Okabe ◽  
Y. Yokoyama
Keyword(s):  
Experimental Studies ◽  
Directional Characteristic ◽  
Vibratory Feeder ◽  
The Mean ◽  
Theoretical Results

This paper treats the motion of a particle on a vibratory feeder whose track has directional characteristic in repulsive motion, for examples, obliquely bristled track, obliquely sliced track and so on. Under some assumptions, the practical equation for predicting the mean conveying velocity is shown and the relations between conveying condition and the mean conveying velocity are clarified theoretically. These relations are shown in various diagrams. Referring these diagrams, the optimum conveying conditions are discussed also. The theoretical results show that the mean conveying velocity is considerably larger than that of the ordinary feeder. The theoretical results are confirmed by experimental studies.

scholarly journals MHD-waves in the geomagnetic tail: A review

10.12737/7168 ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 4-22 ◽  
Author(s):  
Анатолий Леонович ◽  
Anatoliy Leonovich ◽  
Виталий Мазур ◽  
Vitaliy Mazur ◽  
Даниил Козлов ◽  
...  
Keyword(s):  
Numerical Models ◽  
Experimental Studies ◽  
Low Frequency ◽  
Detailed Comparison ◽  
Mhd Waves ◽  
Theoretical Studies ◽  
Geomagnetic Tail ◽  
Magnetopause Oscillations ◽  
Experimental And Theoretical Studies ◽  
Theoretical Results

This article presents the review of experimental and theoretical studies on ultra-low-frequency MHD oscillations of the geomagnetic tail. We consider the Kelvin–Helmholtz instability at the magnetopause, oscillations with a discrete spectrum in the “magic frequencies” range, the ballooning instability of coupled Alfvén and slow magnetosonic waves, and “flapping” oscillations of the current sheet of the geomagnetic tail. Over the last decade, observations from THEMIS, CLUSTER and Double Star satellites have been of great importance for experimental studies. The use of several spacecraft allows us to study the structure of MHD oscillations with high spatial resolution. Due to this, we can make a detailed comparison between theoretical results and those obtained from multi-spacecraft studies. To make such comparisons in theoretical studies, in turn, we have to use the numerical models closest to the real magnetosphere.

scholarly journals UNIVERSAL THREE-PHASE FERRORESONANCE STABILIZERS

2016 ◽  
Vol 19 (1) ◽  
Author(s):  
GEORGI GEORGIEV ◽  
NADEZHDA EVSTATIEVA
Keyword(s):  
Comparative Analysis ◽  
Experimental Studies ◽  
Voltage Stabilizer ◽  
Satisfactory Accuracy ◽  
Three Phase ◽  
Theoretical Results

A comparative analysis has been carried out on two options of three-phase parametric current sources (inductive-capacitive stabilizers). Their capacities to operate in voltage stabilizer mode have been studied. Such capacities were proven and their conditions were defined. Theoretical results were experimentally checked and confirmed with satisfactory accuracy. Based on theoretical and experimental studies it was proven that the considered systems can operate in both modes – as current and voltage stabilizers.

Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity

2006 ◽  
Vol 49 (6) ◽  
pp. 683-701 ◽  
Author(s):  
Dehua Chen ◽  
Xiuming Wang ◽  
Jiansheng Cong ◽  
Delong Xu ◽  
Yanjie Song ◽  
...  
Keyword(s):  
Cylindrical Cavity ◽  
Rock Sample ◽  
Experimental Studies

Nonlinear behaviour of contained inertia waves

1996 ◽  
Vol 315 ◽  
pp. 151-173 ◽  
Author(s):  
Richard Manasseh
Keyword(s):  
Fundamental Mode ◽  
Experimental Studies ◽  
Higher Order ◽  
Time Dependent ◽  
Linear Wave ◽  
Wave System ◽  
Nonlinear Behaviour ◽  
Rotating Fluid ◽  
Weakly Nonlinear ◽  
Higher Order Modes

Rotating fluid-filled containers are systems which admit inertial oscillations, which at appropriate frequencies can be represented as inertia wave modes. When forced by a time-dependent perturbation, systems of contained inertia waves have been shown, in a number of experimental studies, to exhibit complex and varied breakdown phenomena. It is particularly hard to determine a forcing amplitude below which breakdowns do not occur but at which linear wave behaviour is still measurable. In this paper, experiments are presented where modes of higher order than the fundamental are forced. These modes exhibit more complex departures from linear inviscid behaviour than the fundamental mode. However, the experiments on higher-order modes show that instabilities begin at nodal planes. It is shown that even a weakly nonlinear contained inertia-wave system is one in which unexpectedly efficient interactions with higher-order modes can occur, leading to ubiquitous breakdowns. An experiment with the fundamental mode illustrates the system's preference for complex transitions to chaos.

On the spin-up and spin-down of a rotating fluid. Part 2. Measurements and stability

1976 ◽  
Vol 77 (4) ◽  
pp. 709-735 ◽  
Author(s):  
Patrick D. Weidman
Keyword(s):  
Stability Boundary ◽  
Fluid Motion ◽  
Azimuthal Velocity ◽  
Laser Doppler Velocimeter ◽  
Rotating Fluid ◽  
Constant Acceleration ◽  
Centrifugal Instability ◽  
The Stability ◽  
Theoretical Results

Measurements of the azimuthal velocity inside a cylinder which spins up or spins down at constant acceleration were obtained with a laser-Doppler velocimeter and compared with the theoretical results presented in part 1. Velocity profiles near the wave front in spin-up indicate that the velocity discontinuity given by the inviscid Wedemeyer model is smoothed out in a shear layer whose thickness varies with radius and time but scales with hE1/4Ω. The spin-down profiles are always in excellent agreement with theory when the flow is stable. Visualization studies with aluminium tracers have made possible the determination of the stability boundary for Ekman spiral waves (principally type II waves) observed on the cylinder end walls during spin-up. For spin-down to rest the flow always experienced a centrifugal instability which ultimately disrupted the interior fluid motion.

scholarly journals Theoretical and Experimental Studies on the C15 Intermetallic Compound NbCr2

1994 ◽  
Vol 364 ◽  
Author(s):  
F. Chu ◽  
D. J. Thoma ◽  
Y. He ◽  
T. E. Mitchell ◽  
S. P. Chen ◽  
...  
Keyword(s):  
Total Energy ◽  
Elastic Moduli ◽  
Experimental Studies ◽  
Atomic Sphere ◽  
Solubility Range ◽  
Volume Curve ◽  
Lmto Method ◽  
Sphere Approximation ◽  
Structure Density ◽  
Theoretical Results

AbstractThe electronic structure and total energy of the C15 NbCr2 phase have been calculated using the linear muffin-tin orbital (LMTO) method with the atomic sphere approximation (ASA). The total energy vs. volume curve, band structure, density of states and Fermi surface were obtained. The calculated results were used to examine several features of the C15 phase, including the elastic properties, phase formation and stability, and solubility range of the C15 phase. The theoretical results are compared to experimental studies on NbCr2 For example, the elastic moduli, phase stability, and homogeneity range have been determined with a variety of experimental techniques. Comparison of the experimental and theoretical results will be discussed.

CHARACTERISTICS OF MESOSCOPIC PHASE TRANSITIONS IN TWO-DIMENSIONAL SIMPLE NANOSTRUCTURED MATERIALS

2003 ◽  
Vol 17 (25) ◽  
pp. 4539-4554 ◽  
Author(s):  
YOSHITAKE YAMAZAKI ◽  
HERBERT GLEITER ◽  
CHENXU WU ◽  
VLADISLAV ALYOSHIN ◽  
JULY KRASILNIKOVA ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Nanostructured Materials ◽  
Critical Phenomena ◽  
Experimental Studies ◽  
Inert Gas ◽  
Computational Results ◽  
Two Dimensional ◽  
Metropolis Monte Carlo ◽  
Renormalization Theory ◽  
Theoretical Results

In order to study nanostructured materials, a fundamental framework of the theory and the computer-experimental studies is established. The essential characteristics of the mesoscopic phase transitions and critical phenomena in these materials are evaluated by means of this approach. For nanostructured materials consisting of inert gas atoms, we study mesoscopic phase transitions and critical phenomena by generalizing the renormalization theory and the Metropolis Monte Carlo method. The results obtained by the both methods are reported in two papers: computational results in the present paper and the theoretical results in the paper which follows.

scholarly journals Runtime Analysis of Restricted Tournament Selection for Bimodal Optimisation

2021 ◽  
pp. 1-26
Author(s):  
Edgar Covantes Osuna ◽  
Dirk Sudholt
Keyword(s):  
Distance Measure ◽  
Experimental Studies ◽  
Window Size ◽  
Population Diversity ◽  
Single Individual ◽  
Niching Methods ◽  
Size Population ◽  
Tournament Selection ◽  
Theoretical Results ◽  
Shed Light

Abstract Niching methods have been developed to maintain the population diversity, to investigate many peaks in parallel and to reduce the effect of genetic drift. We present the first rigorous runtime analyses of restricted tournament selection (RTS), embedded in a (μ+1) EA, and analyse its effectiveness at finding both optima of the bimodal function TwoMax. In RTS, an offspring competes against the closest individual, with respect to some distance measure, amongst w (window size) population members (chosen uniformly at random with replacement), to encourage competition within the same niche. We prove that RTS finds both optima on TwoMax efficiently if the window size w is large enough. However, if w is too small, RTS fails to find both optima even in exponential time, with high probability. We further consider a variant of RTS selecting individuals for the tournament without replacement. It yields a more diverse tournament and is more effective at preventing one niche from taking over the other. However, this comes at the expense of a slower progress towards optima when a niche collapses to a single individual. Our theoretical results are accompanied by experimental studies that shed light on parameters not covered by the theoretical results and support a conjectured lower runtime bound.

PECULIARITIES OF THE DEVELOPMENT AND MANUFACTURING OF THE PROTOTYPE OF GAPLESS PLANETARY ROLLER SCREW MECHANISM

2019 ◽  
pp. 3-12
Author(s):  
D. S. Blinov ◽  
D. K. Dragun ◽  
A. S. Nosov
Keyword(s):  
Load Capacity ◽  
New Technology ◽  
Experimental Studies ◽  
Radial Deformation ◽  
Short Life ◽  
Low Load ◽  
Roller Screw ◽  
Metrological Control ◽  
Screw Mechanism ◽  
Theoretical Results

Known designs of gapless planetary roller screw mechanisms (PRSM) are highly accurate and rigid, but have low load capacity and short life. To eliminate these shortcomings, a new design of a gapless PRSM was developed and patented using a one-piece thin-walled nut. Due to radial deformation of the nut, the gaps between the threaded parts of the mechanism are chosen. The previous works have described the design of a new gapless PRSM and theoretically proved the possibility of a significant increase in load capacity and life using this mechanism. To confirm the theoretical results and conclusions, it is necessary to conduct experimental studies for which a prototype of the new gapless PRSM was made. The work presented describes a new technology for manufacturing threaded parts of this mechanism. In contrast to the traditional technology of grinding screw surfaces of the PRSM parts, which require special expensive equipment, it is proposed to grind and bore the screw surfaces of the parts with special plates on CNC turning machines. The metrological control has established that the dimensions of all parts of the prototype, including the threaded parts, did not go beyond the fields of the calculated or assigned tolerances.

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