scholarly journals Nonlinear waves in cylinder shell containing viscous liquid, under the impact of surrounding elastic medium and structural damping in longitudinal direction

2018 ◽  
Vol 26 (6) ◽  
pp. 32-47
Author(s):  
E. V. Evdokimova ◽  
◽  
Yu. A. Blinkov ◽  
L. I. Mogilevich ◽  
◽  
...  
Keyword(s):  
Elastic Medium ◽  
Viscous Liquid ◽  
Nonlinear Waves ◽  
Longitudinal Direction ◽  
Structural Damping ◽  
The Impact

Duffin–Kemmer–Petiau oscillator in the presence of a cosmic screw dislocation

2020 ◽  
Vol 35 (30) ◽  
pp. 2050195
Author(s):  
Soroush Zare ◽  
Hassan Hassanabadi ◽  
Marc de Montigny
Keyword(s):  
Elastic Medium ◽  
Screw Dislocation ◽  
Topological Defect ◽  
Potential Functions ◽  
Wave Functions ◽  
Screw Dislocations ◽  
Energy Eigenvalues ◽  
Heun Function ◽  
Uvarov Method ◽  
The Impact

We examine the behavior of spin-zero bosons in an elastic medium which possesses a screw dislocation, which is a type of topological defect. Therefore, we solve analytically the Duffin–Kemmer–Petiau (DKP) oscillator for bosons in the presence of a screw dislocation with two types of potential functions: Cornell and linear-plus-cubic potential functions. For each of these functions, we analyze the impact of screw dislocations by determining the wave functions and the energy eigenvalues with the help of the Nikiforov–Uvarov method and Heun function.

Stability of strong electromagnetic waves in overdense plasmas against long-wavelength perturbations

1985 ◽  
Vol 33 (2) ◽  
pp. 285-301 ◽  
Author(s):  
F. J. Romeiras ◽  
G. Rowlands
Keyword(s):  
Dispersion Relation ◽  
Nonlinear Waves ◽  
Electromagnetic Waves ◽  
Modulation Depth ◽  
Longitudinal Direction ◽  
Transverse Component ◽  
Ion Density ◽  
Long Wavelength ◽  
The Stability ◽  
Two Parameters

We consider the stability against long-wavelength small parallel perturbations of a class of exact standing wave solutions of the equations that describe an unmagnetized relativistic overdense cold electron plasma. The main feature of these nonlinear waves is a circularly polarized transverse component of the electric field periodically modulated in the longitudinal direction. Using an analytical method developed by Rowlands we obtain a dispersion relation valid for long-wavelength perturbations. This dispersion relation is a biquadratic equation in the phase velocity of the perturbations whose coefficients are very complicated functions of the two parameters used to define the nonlinear waves: the normalized ion density and a quantity related to the modulation depth. This dispersion relation is discussed for the whole range of the two parameters revealing, in particular, the existence of a region in parameter space where the nonlinear waves are stable.

scholarly journals Hydrodynamics of Two-Phase Gas-Very Viscous Liquid Flow in Heat Exchange Conditions

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5709
Author(s):  
Krystian Czernek ◽  
Stanisław Witczak
Keyword(s):  
Liquid Film ◽  
Viscous Liquid ◽  
Capillary Waves ◽  
Liquid Cooling ◽  
Two Phase ◽  
Flow Parameters ◽  
Smooth Interface ◽  
Viscous Liquid Film ◽  
Vertical Tubes ◽  
The Impact

This paper presents the results of analyses of the impact of heat transfer conditions on the hydrodynamics of downward co-current annular flow in vertical tubes of very viscous liquid and gas. The research was conducted within the range of gas velocities of 0–30.0 m/s and liquid velocities of 0.001–0.254 m/s, while the viscosity was in the unprecedented range of 0.046–3.5 Pas. The research demonstrates that the volume and nature of the liquid waves with various amplitudes and frequencies arising on the surface of the film are relative to the flow rate and viscosity of the gas phase. At the same time, we found that, under the condition of liquid cooling, an increase in viscosity resulted in the formation of a smooth interface whereas, under the conditions where the liquid is heated at the end of the channel section, a greater number of capillary waves were formed. This research resulted in the development of new dependencies which take into account the influence of selected thermal and flow parameters (including mass fraction) on the values of volumes specific to very viscous liquid film flows. These dependencies improve the accuracy of calculation by 8–10% and are fully applicable to the description of the performance of an apparatus with a hydraulically generated liquid film.

Range Prediction and Trajectory Correction of Long Range Rocket with Attitude Stabilization

2012 ◽  
Vol 232 ◽  
pp. 299-304
Author(s):  
Ke Yong Li ◽  
Fen Fen Xiong ◽  
Cheng Zhang ◽  
Shi Shi Chen
Keyword(s):  
Long Range ◽  
Prediction Method ◽  
Longitudinal Direction ◽  
Control Mode ◽  
Attitude Stabilization ◽  
Large Dispersion ◽  
Range Correction ◽  
And Control ◽  
Range Error ◽  
The Impact

The dispersion of long range rocket is significantly suppressed by the attitude stabilization in the boost phase. However, the attitude stabilization system cannot govern the propellant impulse error and mass error, which induces large dispersion in the longitudinal direction. Therefore, it is necessary to conduct range correction in the post-boost phase of flight trajectory. A range prediction method based on the elliptic ballistic theory is proposed in this paper. Elliptic ballistic equations and range estimation equations are derived and the modified range prediction method with correction factor is presented. It is verified that the proposed method can predict the residual flight range accurately. After that, the lateral pulse jets control is presented and utilized to correct the trajectory and eliminate the range error. A unique control law is reported that combines elliptic ballistic theory and control mode for lateral pulse jets. The impact point is directly controlled and rocket dispersion in the longitudinal direction is efficiently reduced.

The Effect of Pre-Strain and Strain Aging on Properties of X100 Line Pipe

2013 ◽  
Vol 690-693 ◽  
pp. 2270-2274
Author(s):  
Qiu Rong Ma ◽  
Hong Da Chen ◽  
Yan Hua Li ◽  
He Li
Keyword(s):  
Tensile Strength ◽  
Impact Toughness ◽  
Yield Strength ◽  
Tensile Properties ◽  
Aging Temperature ◽  
Strain Aging ◽  
Longitudinal Direction ◽  
Line Pipe ◽  
Toughness Test ◽  
The Impact

Tensile and impact toughness test on X100 line pipe with different pre-strain at different aging temperature were conducted to study the effect of pre-strain and aging temperature on properties of X100 line pipe. The result shows that yield strength and tensile strength of X100 line pipe would increase significantly with the introduction of pre-strain, while the impact toughness would decrease significantly. Effect of strain aging on tensile properties of X100 line pipe are more significantly. The yield strength, and tensile strength would increase significantly with the introduction of strain aging both transversal and longitudinal direction.

scholarly journals Torsional and longitudinal vibration of suspension bridge subject to aerodynamic forces

1998 ◽  
Vol 4 (5) ◽  
pp. 393-421 ◽  
Author(s):  
N. U. Ahmed ◽  
H. Harbi
Keyword(s):  
Longitudinal Vibration ◽  
Suspension Bridge ◽  
Stability Of Motion ◽  
Structural Damping ◽  
Aerodynamic Forces ◽  
Coupled Partial Differential Equations ◽  
The Road ◽  
The Stability ◽  
The Impact ◽  
Nonlinear Operation

In this paper we consider a dynamic model of suspension bridge governed by a pair of coupled partial differential equations which describe both torsional and longitudinal vibration of the road bed. The vertical and torsional motions are coupled through a nonlinear operation with the nonlinearity arising from loss of tension in the vertical cables supporting the decks. We study the impact of wind forces on the stability of motion of this system both in the absence and presence of viscous and structural damping. The results are illustrated by numerical simulation.

scholarly journals Foil Bearing Design Guidelines for Improved Stability

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
J. Schiffmann ◽  
Z. S. Spakovszky
Keyword(s):  
Pressure Distribution ◽  
Mass Parameter ◽  
Critical Mass ◽  
Design Guidelines ◽  
Fluid Film ◽  
Structural Damping ◽  
Foil Bearing ◽  
Improved Stability ◽  
Bearing Design ◽  
The Impact

Experimental evidence in the literature suggests that foil bearing-supported rotors can suffer from subsynchronous vibration. While dry friction between top foil and bump foil is thought to provide structural damping, subsynchronous vibration is still an unresolved issue. The current paper aims to shed new light onto this matter and discusses the impact of various design variables on stable foil bearing-supported rotor operation. It is shown that, while a time domain integration of the equations of motion of the rotor coupled with the Reynolds equation for the fluid film is necessary to quantify the evolution of the rotor orbit, the underlying mechanism and the onset speed of instability can be predicted by coupling a reduced order foil bearing model with a rigid-body, linear, rotordynamic model. A sensitivity analysis suggests that structural damping has limited effect on stability. Further, it is shown that the location of the axial feed line of the top foil significantly influences the bearing load capacity and stability. The analysis indicates that the static fluid film pressure distribution governs rotordynamic stability. Therefore, selective shimming is introduced to tailor the unperturbed pressure distribution for improved stability. The required pattern is found via multiobjective optimization using the foil bearing-supported rotor model. A critical mass parameter is introduced as a measure for stability, and a criterion for whirl instability onset is proposed. It is shown that, with an optimally shimmed foil bearing, the critical mass parameter can be improved by more than two orders of magnitude. The optimum shim patterns are summarized for a variety of foil bearing geometries with different L/D ratios and different degrees of foil compliance in a first attempt to establish more general guidelines for stable foil bearing design. At low compressibility (Λ < 2), the optimum shim patterns vary little with bearing geometry; thus, a generalized shim pattern is proposed for low compressibility numbers.

scholarly journals Nonlinear Waves Mathematical Modeling in Coaxial Shells Filled with Viscous Liquid

2016 ◽  
Vol 16 (3) ◽  
pp. 331-336
Author(s):  
Yu. A. Blinkov ◽  
◽  
Yu. N. Kondratova ◽  
A. V. Mesyanzhin ◽  
L. I. Mogilevich ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Viscous Liquid ◽  
Nonlinear Waves

scholarly journals Microstructure and mechanical properties of different keratinous horns

2018 ◽  
Vol 15 (143) ◽  
pp. 20180093 ◽  
Author(s):  
Yuchen Zhang ◽  
Wei Huang ◽  
Cheryl Hayashi ◽  
John Gatesy ◽  
Joanna McKittrick
Keyword(s):  
Mechanical Properties ◽  
Longitudinal Direction ◽  
Bighorn Sheep ◽  
Growth Direction ◽  
Ovis Aries ◽  
Domestic Sheep ◽  
Microstructure And Mechanical Properties ◽  
Mountain Goat ◽  
The Impact ◽  
Horn Core

Animal horns play an important role during intraspecific combat. This work investigates the microstructure and mechanical properties of horns from four representative ruminant species: the bighorn sheep ( Ovis canadensis ), domestic sheep ( Ovis aries ), mountain goat ( Oreamnos americanus ) and pronghorn ( Antilocapra americana ), aiming to understand the relation between evolved microstructures and mechanical properties. Microstructural similarity is found where disc-shaped keratin cells attach edge-to-edge along the growth direction of the horn core (longitudinal direction) forming a lamella; multiple lamellae are layered face to face along the impact direction (radial direction, perpendicular to horn core growth direction), forming a wavy pattern surrounding a common feature, the tubules. Differences among species include the number and shape of the tubules, the orientation of aligned lamellae and the shape of keratin cells. Water absorption tests reveal that the pronghorn horn has the largest water-absorbing ability due to the presence of nanopores in the keratin cells. The loading direction (compressive and tensile) and level of hydration vary among the horns from different species. The differences in mechanical properties among species may relate to their different fighting behaviours: high stiffness and strength in mountain goat to support the forces during stabbing; high tensile strength in pronghorn for interlocked pulling; impact energy absorption properties in domestic and bighorn sheep to protect the skull during butting. These design rules based on evolutionary modifications among species can be applied in synthetic materials to meet different mechanical requirements.

Parity Negatively Impacts the Uniaxial Mechanical Properties of the Vagina in the Ewe

2013 ◽  
Author(s):  
Katrina Knight ◽  
Pamela Moalli ◽  
Stacy Palcsey ◽  
William Barone ◽  
Steven D. Abramowitch
Keyword(s):  
Mechanical Properties ◽  
Psychological Health ◽  
Strain Energy ◽  
Negative Impact ◽  
Longitudinal Direction ◽  
Pelvic Organ ◽  
Exact Etiology ◽  
Physical And Psychological Health ◽  
The Impact ◽  
Female Sheep

Pelvic organ prolapse (POP) is a common disorder with a profoundly negative impact on the physical and psychological health of women worldwide; however, the exact etiology is currently unknown. Parity, defined as the number of births, is commonly identified as one of the leading risk factors for the development of POP. The objective of this study was to examine the impact of parity on the uniaxial mechanical properties of the sheep vagina along the longitudinal direction. The findings of this study revealed that parity negatively impacts the tangent modulus (54% decrease), tensile strength (54% decrease), and strain-energy density (47% decrease) of the vagina in the ewe (female sheep). Based on similar findings in primate, these data suggest that the ewe may serve as a cheaper alternative for studying the pathogenesis of POP moving forward.

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