Critical rotation frequency for vortices configuration in a harmonically trapped boson atoms

2020 ◽  
Vol 0 (0) ◽  
pp. 0-0
Author(s):  
Alyaa Mahmoud ◽  
Ahmed Hassan ◽  
Shemi Soliman
Keyword(s):  
Rotation Frequency ◽  
Critical Rotation

Selection of a mother wavelet as identification pattern for the detection of cracks in shafts

2021 ◽  
pp. 107754632110260
Author(s):  
Marta Zamorano ◽  
María Jesus Gómez Garcia ◽  
Cristina Castejón
Keyword(s):  
Standard Method ◽  
Wavelet Packet ◽  
Rotation Frequency ◽  
Wavelet Function ◽  
Classification Systems ◽  
Mother Wavelet ◽  
Decomposition Level ◽  
Rotating Shaft ◽  
Critical Rotation ◽  
Selection Of

Nowadays, there are many methods to detect and diagnose defects in mechanical components during operation. The newest methods that can be found in the literature are based on intelligent classification systems and evaluation of patterns to obtain a diagnosis; however, there is not any standard method to assess features. Wavelet packet transform allows to obtain interesting patterns for evaluating the condition of rotating elements. To perform this calculation, it is necessary to select a series of parameters that affect the resulting pattern. These parameters are the decomposition level and the mother wavelet function. A detailed methodology for the selection of the mother wavelet is proposed, which is the aim of this work, to obtain the most suitable patterns in the diagnostic task. This proposed methodology is applied to data obtained from a rotating shaft with a crack located at the change of section. These signals were measured at low rotation frequency (below the critical rotation frequency) and without eccentricity, where detection becomes more complex.

Uniaxial and biaxial nematic liquid crystals

2006 ◽  
Vol 364 (1847) ◽  
pp. 2681-2696 ◽  
Author(s):  
T.J Dingemans ◽  
L.A Madsen ◽  
N.A Zafiropoulos ◽  
Wenbin Lin ◽  
E.T Samulski
Keyword(s):  
Nematic Phase ◽  
Mean Field ◽  
Rotation Frequency ◽  
General Context ◽  
Rotation Rates ◽  
Critical Rotation ◽  
Biaxial Nematics ◽  
Nematic Phases ◽  
Lower Temperature ◽  
Biaxial Nematic

The unusual exhibition of a biaxial nematic phase in nonlinear thermotropic mesogens derived from the 2,5-oxadiazole biphenol (ODBP) core is placed in a general context; the uniaxial nematic phase of the prototypical rod-like mesogen para -quinquephenyl does not follow the classical mean-field behaviour of nematics, thus questioning the utility of such theories for quantitative predictions about biaxial nematics. The nuclear magnetic resonance spectra of labelled probe molecules dissolved in ODBP biaxial nematic phases suggest that a second critical rotation frequency, related to the differences in the transverse diamagnetic susceptibilities of the biaxial nematic, must be exceeded in order to create an aligned two-dimensional powder sample. Efforts to find higher viscosity and lower temperature biaxial nematics (with lower critical rotation rates) to confirm the above conjecture are described. Several chemical modifications of the ODBP mesogenic core are presented.

TRIAL SOLUTION AND CRITICAL FREQUENCY TO THE SINGLY QUANTIZED VORTEX IN BIG BOSE–EINSTEIN CONDENSATES

2006 ◽  
Vol 20 (16) ◽  
pp. 995-1005
Author(s):  
YAN XU ◽  
DUOJE JIA ◽  
ZHAOYANG CHEN
Keyword(s):  
Critical Frequency ◽  
Vortex Formation ◽  
Rotation Frequency ◽  
Boundary Region ◽  
Quantized Vortex ◽  
Trial Solution ◽  
Topological Soliton ◽  
Critical Rotation ◽  
Coupling Parameters ◽  
Bose Einstein

A novel solution to the singly quantized vortex is presented for big Bose–Einstein condensates in axis-symmetric harmonic traps, which is valid in the regime of strong coupling parameters. This solution manifests the vortex as a topological soliton and describes correctly its global structure for the whole region of large condensates including the vortex-core, except for the thin boundary region. An improved expression for thermodynamical critical rotation frequency for vortex formation is derived based on our solution, conforming to the known frequency formula given by Lundh et al. in the Thomas–Fermi limit.

Electric Drill Drive with Intermediate Rolling Members Reducer

2015 ◽  
Vol 756 ◽  
pp. 24-28 ◽  
Author(s):  
V.S. Korotkov ◽  
S.V. Razumov
Keyword(s):  
Rotation Speed ◽  
Rotation Frequency ◽  
Lead Angle ◽  
Critical Rotation ◽  
Different Types ◽  
Calculation Results ◽  
Rolling Elements ◽  
Electric Drill

The article considers briefly the hand power tool market in Russia. The authors set the parameters of a wave gear electric drill with intermediate rolling solids. Its field of application is also described. The design is developed on the basis of a commutator motor with a useful capacity 1,0 kW. The rotation speed ​​of the motor armature is 15000 rpm. The rational rotation frequency of an auger working body is 200...300rpm. It is necessary to create a gear with a ratio 59 and with parameters comparable to the size of a hand-held machine engine in order to have esthetics. In this case, the diameter of rolling elements should lie in the range 2 to 3 mm. The authors made a research on hand-held electric drill runnability with such characteristics. They presented dependency diagrams of an auger working body critical rotation frequency from a lead angle while drilling different types of soil. They determined important power and geometrical criteria to design a gearbox. The calculation results are presented in tables.

Development of an Electromagnetic Brake for Stabilizing the Ram Air Turbine Rotation Frequency

2020 ◽  
Vol 8 (8) ◽  
pp. 37-43
Author(s):  
Anton A. SHIROKOV ◽  
◽  
Dmitriy S. DEZHIN ◽  
Marina V. ZDOROVA ◽  
◽  
...  
Keyword(s):  
Rotation Frequency ◽  
Electromagnetic Brake ◽  
Air Turbine

Stress fields in granular material and implications for performance of robot locomotion over granular media

2015 ◽  
Vol 8 (1) ◽  
pp. 2005-2009
Author(s):  
Diandong Ren ◽  
Lance M. Leslie ◽  
Congbin Fu
Keyword(s):  
Mechanical Properties ◽  
Granular Material ◽  
Granular Media ◽  
Rotation Frequency ◽  
Legged Locomotion ◽  
Working Environment ◽  
Navier Stokes ◽  
Maximum Speed ◽  
Sigmoid Curve ◽  
Multi Body

 Legged locomotion of robots has advantages in reducing payload in contexts such as travel over deserts or in planet surfaces. A recent study (Li et al. 2013) partially addresses this issue by examining legged locomotion over granular media (GM). However, they miss one extremely significant fact. When the robot’s wheels (legs) run over GM, the granules are set into motion. Hence, unlike the study of Li et al. (2013), the viscosity of the GM must be included to simulate the kinematic energy loss in striking and passing through the GM. Here the locomotion in their experiments is re-examined using an advanced Navier-Stokes framework with a parameterized granular viscosity. It is found that the performance efficiency of a robot, measured by the maximum speed attainable, follows a six-parameter sigmoid curve when plotted against rotating frequency. A correct scaling for the turning point of the sigmoid curve involves the footprint size, rotation frequency and weight of the robot. Our proposed granular response to a load, or the ‘influencing domain’ concept points out that there is no hydrostatic balance within granular material. The balance is a synergic action of multi-body solids. A solid (of whatever density) may stay in equilibrium at an arbitrary depth inside the GM. It is shown that there exists only a minimum set-in depth and there is no maximum or optimal depth. The set-in depth of a moving robot is a combination of its weight, footprint, thrusting/stroking frequency, surface property of the legs against GM with which it has direct contact, and internal mechanical properties of the GM. If the vehicle’s working environment is known, the wheel-granular interaction and the granular mechanical properties can be grouped together. The unitless combination of the other three can form invariants to scale the performance of various designs of wheels/legs. Wider wheel/leg widths increase the maximum achievable speed if all other parameters are unchanged.

Bisynchronous Torsional Vibrations in Rotating Shafts

1987 ◽  
Vol 54 (4) ◽  
pp. 893-897 ◽  
Author(s):  
O. Bernasconi
Keyword(s):  
Angular Momentum ◽  
Nonlinear Term ◽  
Rotation Frequency ◽  
Longitudinal Component ◽  
Torsional Vibrations ◽  
Rotating Shaft ◽  
Rotating Shafts

In this study, the intrinsic behavior of rotating shafts with residual unbalance is considered. The longitudinal component of the angular momentum caused by synchronous precession (whirling) induces torsional vibrations with a frequency of twice the rotation frequency (bisynchronous). The nonlinear term which represents this coupling is characteristic of the asymmetrical aspect of rotating shaft kinematics. This result has been obtained analytically and confirmed experimentally.

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