Viscoplastic Lubrication of Asperities

1982 ◽  
Vol 104 (4) ◽  
pp. 568-574 ◽  
Author(s):  
S. Sheu ◽  
W. R. D. Wilson
Keyword(s):  
Experimental Investigations ◽  
Viscoplastic Liquid ◽  
Factors Influencing ◽  
Theoretical Analyses

Theoretical analyses for the lubrication of rigid wedge-shaped asperities by a viscoplastic liquid are developed. Two cases are considered in which wedge action and squeeze action are dominant. The results of the analyses are compared with previous experimental investigations of the factors influencing susceptibility to lubrication failure.

scholarly journals Superfluid Properties of Superconductors with Disorder at the Nanoscale: A Random Impedance Model

2020 ◽  
Vol 5 (2) ◽  
pp. 36
Author(s):  
Giulia Venditti ◽  
Ilaria Maccari ◽  
Marco Grilli ◽  
Sergio Caprara
Keyword(s):  
Superconducting State ◽  
Transition Metal Dichalcogenides ◽  
Mean Field ◽  
Metallic Matrix ◽  
Proximity Effects ◽  
Experimental Investigations ◽  
Impedance Model ◽  
Metal Dichalcogenides ◽  
Effective Medium Approach ◽  
Theoretical Analyses

Some two-dimensional superconductors like, e.g., LaAlO 3 /SrTiO 3 heterostructures or thin films of transition metal dichalcogenides, display peculiar properties that can be understood in terms of electron inhomogeneity at the nanoscale. In this framework, unusual features of the metal-superconductor transition have been interpreted as due to percolative effects within a network of superconducting regions embedded in a metallic matrix. In this work we use a mean-field-like effective medium approach to investigate the superconducting phase below the critical temperature T c at which the resistivity vanishes. Specifically, we consider the finite frequency impedance of the system to extract the dissipative part of the conductance and the superfluid stiffness in the superconducting state. Intriguing effects arise from the metallic character of the embedding matrix: upon decreasing the temperature below T c proximity effects may rapidly increase the superfluid stiffness. Then, a rather fragile superconducting state, living on a filamentary network just below T c , can be substantially consolidated by additional superconducting regions induced by proximity effect in the interstitial metallic regions. This mean-field prediction should call for further theoretical analyses and trigger experimental investigations of the superconducting properties of the above systems.

A review of recent experimental investigations and theoretical analyses for pulsating heat pipes

2013 ◽  
Vol 7 (2) ◽  
pp. 161-173 ◽  
Author(s):  
Xin Tang ◽  
Lili Sha ◽  
Hua Zhang ◽  
Yonglin Ju
Keyword(s):  
Heat Pipes ◽  
Experimental Investigations ◽  
Theoretical Analyses

Experimental Investigation of Blade Rows Interactions in Contra-Rotating Axial Flow Pump

2014 ◽  
Author(s):  
Linlin Cao ◽  
Hironori Honda ◽  
Hiroaki Yoshimura ◽  
Satoshi Watanabe ◽  
Akinori Furukawa
Keyword(s):  
Pressure Fluctuation ◽  
Axial Flow ◽  
Potential Interaction ◽  
Experimental Investigations ◽  
Cavitation Performance ◽  
Rotor Stator Interaction ◽  
Frequency Components ◽  
Axial Flow Pump ◽  
Theoretical Analyses ◽  
Flow Pump

As a high specific speed pump, the contra-rotating axial flow pump with two rotors rotating reversely has been proved with higher hydraulic and cavitation performance, while in our previous researches, our prototype rotors designed with equal rotational speeds for both the front and the rear rotors was also confirmed with the strong potential interaction between two blade rows. In the present study, the experimental investigations were focused on the rotor-rotor interactions in the contra-rotating rotors under two rotational speed combinations, an equal speed and a different speed ones with the lower speed of rear rotor; the latter is determined aiming at relieved rotor-rotor interaction. As the major experimental approach, casing wall static pressure measurements were conducted at pressure taps covering from upstream to downstream of the both rotors, and the pressure fluctuation modes were investigated by the FFT analyses. By series of pressure taps with different peripheral locations prepared at several axial locations, the pressure fluctuation modes with frequencies non-synchronous to the BPF (blade passing frequency) components were recognized, and confirmed to be related to the rotor-rotor interaction on the basis of theoretical analyses on the rotor-stator interaction in conventional rotor-stator types.

Research on Compensation of Nonlinearity in Heterodyne Interferometer

2010 ◽  
Vol 36 ◽  
pp. 303-310 ◽  
Author(s):  
Wen Mei Hou ◽  
Xiao Ren
Keyword(s):  
Experimental Investigations ◽  
Test Results ◽  
Heterodyne Interferometer ◽  
Theoretical Analyses

The demands of nano-measurement and nano-positioning now in research and industries become the challenge for heterodyne interferometer because its nonlinearity often limits the effective resolution. This paper introduces new developed method for compensation of the nonlinearity in heterodyne interferometer and explains what accuracy can be reached with demonstrations figured by the test results. On the basis of theoretical analyses and experimental investigations it shows which exactness can be expected.

scholarly journals Dynamic response of monolithic and sandwich structures subjected to impulsive and impact loadings

2017 ◽  
Vol 21 (8) ◽  
pp. 1134-1147 ◽  
Author(s):  
Xinmei Xiang ◽  
Guoxing Lu ◽  
Zhongxian Li ◽  
Dong Ruan
Keyword(s):  
Failure Modes ◽  
Sandwich Structures ◽  
Impulsive Loading ◽  
Low Velocity Impact ◽  
Experimental Investigations ◽  
Low Velocity ◽  
Velocity Impact ◽  
Monolithic Structures ◽  
Theoretical Analyses ◽  
Theoretical Results

Monolithic and sandwich structures have been widely used as energy absorption structures in military and civil engineering. This article reviews theoretical analyses of monolithic beams and plates subjected to static loading, impulsive loading and impact by a mass systematically. Experimental data collected from the literatures are compared with these theoretical results. In addition, the critical impulses for the failure of the monolithic structures are also reviewed. Furthermore, sandwich structures under quasi-static, low-velocity impact, high-velocity impact and blast loading, as well as their failure modes, are also summarized. The research methodology involves experimental investigations, theoretical analyses and numerical simulations.

Free and Forced Response of a Piecewise Linear 2-DOF System: Analysis and Experiments

2009 ◽  
Author(s):  
Fabrizio Vestroni ◽  
Paolo Casini ◽  
Oliviero Giannini
Keyword(s):  
System Analysis ◽  
Piecewise Linear ◽  
Damage Parameter ◽  
Forced Response ◽  
Experimental Investigations ◽  
Restoring Force ◽  
Proposed Model ◽  
Wide Range ◽  
Set Up ◽  
Theoretical Analyses

The present paper analyzes the free and forced dynamics of a 2-DOF mechanical system with piecewise linear restoring force, by means of analytical/numerical and experimental investigations. This oscillator is roughly representative of an asymmetrically cracked cantilever beam vibrating in bending and hence exhibiting a bilinear stiffness, depending on whether the crack is open or closed. A parametric analysis of the NNMs has been performed for a wide range of the damage parameter: the influence of damage on the nonlinear frequencies has been investigated and bifurcations characterized by the onset of superabundant modes with or without internal resonance, have been revealed. The dynamic behavior of the system under harmonic base excitation has been numerically investigated assuming both low and high damping. It has been found that the NNMs of the free motion play a key role in the system forced response. Finally, a test set-up has then been built to investigate the validity of the proposed model for technical applications: the experimental measurements qualitatively and quantitatively capture the basic bifurcation scenarios anticipated by the model while a strong robustness of the phenomena pointed out by the theoretical analyses has been revealed in the experiments.

scholarly journals CLASSIFICATION OF FACTORS INFLUENCING ENVIRONMENTAL MANAGEMENT OF ENTERPRISE

2016 ◽  
Vol 22 (6) ◽  
pp. 867-884 ◽  
Author(s):  
Tatjana TAMBOVCEVA
Keyword(s):  
Environmental Management ◽  
Environmental Management Systems ◽  
Scientific Publications ◽  
The Sustainable Development ◽  
Factors Influencing ◽  
Survey Results ◽  
The One ◽  
Depth Interviews ◽  
Theoretical Analyses

The modern enterprises consider the sustainable development as the one of basic conceptions of one’s activity. In recent years, an increasing number of private as well as public organizations have been engaged with implementation and using of environmental management systems (EMSs). The research is built up by two main parts. In the first, author prepared theoretical analyses of literature and scientific publications. The second part based on survey results collected from Latvian companies using in depth interviews. Author proposes that the process of environmentally oriented business should be studied as a multi-dimensional issue. Company’s external and internal environment elements were shown. In article author also investigated different factors influencing company’s environmental management and motives of implementing EMS.

scholarly journals Breakdown in air gaps with solid insulating barrier under impulse voltage stress

2005 ◽  
Vol 18 (1) ◽  
pp. 87-104 ◽  
Author(s):  
Frangiskos Topalis ◽  
Michael Danikas
Keyword(s):  
High Voltage ◽  
Theoretical Models ◽  
Experimental Investigations ◽  
Barrier Effect ◽  
High Voltage Electrode ◽  
Insulating Materials ◽  
Air Gaps ◽  
Voltage Stress ◽  
Theoretical Analyses

The influence of solid insulating barriers to the impulse strength of air gaps has been investigated by few researchers. It is well known that thin insulating materials increase considerably the breakdown voltage, sometimes two to three times. Some researchers performed thorough investigations for the determination of the parameters of the barrier effect that influence the impulse level for the breakdown. The distance of the barrier from the high voltage electrode is the most important parameter. The field distribution is also important as well as the shape of the insulating sheet. The experimental investigations led to some theoretical models for the breakdown process. This paper analyzes and discusses those models and spots the points where they agree as well as the differences between them. Finally, it attempts to compose a model that sheds light on the barrier effect and complies with all the experimental and theoretical analyses.

scholarly journals Theoretical and Experimental Investigation of Circumferential Grooved Casing/Hub Treatment

1994 ◽  
Author(s):  
Zhaohui Du ◽  
Zhiwei Liu
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Experimental Investigations ◽  
Operation Condition ◽  
Stall Margin ◽  
3 Dimensional ◽  
Blade Row ◽  
Stator Blade ◽  
Flow Compressor ◽  
Theoretical Analyses

In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments. A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.

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