A Discrete-Continuum Approach to the Solution of the Contact of Rotating Circular Surfaces

1969 ◽  
Vol 91 (3) ◽  
pp. 387-389 ◽  
Author(s):  
E. F. Finkin
Keyword(s):  
Electrical Contact ◽  
Continuum Approach ◽  
Electrical Contact Resistance ◽  
Contact Density ◽  
New Approach ◽  
Real Area Of Contact ◽  
Interfacial Pressure ◽  
Surface Contact ◽  
Discrete Nature ◽  
Insight Into

A new approach to the analysis of problems of surface contact is postulated, which takes into account the discrete nature of the process, but allows the simplicity of continuum methods, where possible; this is termed the discrete-continuum approach. The method is shown by developing the solution of the problem of the nominal interfacial pressure distribution and real area of contact density for rotating nominally flat but rough circular surfaces. The method allows the mathematical statement of the transitions which occur with surface wear, and thereby constitutes a mathematical description of some aspects of run-in. The method and solution to the present problem give insight into the nature of the pattern of contacts, and are therefore expected to find application in surface-contact temperature theory and in electrical-contact resistance theory.

Some Issues of Rough Surface Contact Plasticity at Micro- and Nano-Scales

2004 ◽  
Vol 841 ◽  
Author(s):  
Y. F. Gao ◽  
A. F. Bower ◽  
K.-S. Kim
Keyword(s):  
Rough Surface ◽  
Electrical Contact ◽  
Plasticity Theory ◽  
Point Of View ◽  
Contact Model ◽  
Electrical Contact Resistance ◽  
Surface Plasticity ◽  
Surface Contact ◽  
Rough Surface Contact ◽  
Material Length Scale

ABSTRACTRough surface contact plasticity at microscale and nanoscale is of crucial importance in many new applications and technologies, such as nano-imprinting and nano-welding. This paper summarizes our recent progress in understanding contact plasticity from a multiscale point of view, and also presents our perspectives. We first discuss a contact model based on fractal roughness and continuum plasticity theory. Interestingly, our simple, elastic-plastic contact model of the Weierstrass-Archard type gives rise to many practical scaling relations of contact pressure, contact compliance etc. The usefulness of those predictions is discussed for experimental measurements of the thermal/electrical contact resistance. A material length scale can be introduced by a nonlocal plasticity theory, or implicitly by dislocation mechanics modeling. The recent work on micro-plasticity of surface steps gives a variety of surface yielding and hardening behaviors, depending on interface adhesion, roughness features and slip systems. As a consequence, a rough surface contact at mesoscale can lead to the formation of a boundary layer with sub-layer dislocation structures, which cannot be predicted by existing strain gradient plasticity theories. The micromechanical analysis of surface plasticity could serve as the connection between microscale bulk dislocation plasticity and nanoscale atomistic simulations.

Surface Separation and Contact Resistance Considering Elasto-Plastic Multi-Scale Rough Surface Contact

2007 ◽  
Author(s):  
W. Everett Wilson ◽  
Robert L. Jackson ◽  
Santosh Angadi ◽  
Jeffrey Streator
Keyword(s):  
Contact Resistance ◽  
Rough Surface ◽  
Electrical Contact ◽  
Scale Model ◽  
Surface Geometry ◽  
Electrical Contact Resistance ◽  
Surface Separation ◽  
Multi Scale ◽  
Surface Contact ◽  
Rough Surface Contact

The current work considers the multiscale nature of surface roughness in a new model that predicts the real area of contact and surface separation, all as a function of load. By summing the distance between the two surfaces at all scales, a model of surface separation as a function of dimensionless load is also obtained. The model is also able to make predictions for thermal (and electrical) contact resistance. In striving for a more realistic model, the multi-scale model accounts for the effects of a rough surface geometry ranging from macro down to the nano scale. A previous rough surface contact model was based on stacked elasto-plastic spheres. This work uses stacked 3-D sinusoids to represent the asperities in contact at each scale of the surface. The results are also compared to several other existing rough surface contact models and experimental results.

scholarly journals Can Economic Factors Improve Momentum Trading Strategies? The Case of Managed Futures during the COVID-19 Pandemic

Economies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 86
Author(s):  
Renata Guobužaitė ◽  
Deimantė Teresienė
Keyword(s):  
Financial Markets ◽  
Risk Premium ◽  
Trading Strategies ◽  
Economic Factors ◽  
Momentum Strategies ◽  
New Approach ◽  
Managed Futures ◽  
Asset Classes ◽  
Momentum Trading ◽  
Insight Into

Systematic momentum trading is a prevalent risk premium strategy in different portfolios. This paper focuses on the performance of the managed futures strategy based on the momentum signal across different economic regimes, focusing on the COVID-19 pandemic period. COVID-19 had a solid but short-lived impact on financial markets, and therefore gives a unique insight into momentum strategies’ performance during such critical moments of market stress. We offer a new approach to implementing momentum strategies by adding macroeconomic variables to the model. We test a managed futures strategy’s performance with a well-diversified futures portfolio across different asset classes. The research concludes that constructing a portfolio based on academically/economically sound momentum signals with its allocation timing based on broader economic factors significantly improves managed futures strategies and adds significant diversification benefits to the investors’ portfolios.

scholarly journals Individualized Hemodynamic Management in Sepsis

2021 ◽  
Vol 11 (2) ◽  
pp. 157
Author(s):  
Marcell Virág ◽  
Tamas Leiner ◽  
Mate Rottler ◽  
Klementina Ocskay ◽  
Zsolt Molnar
Keyword(s):  
Fluid Overload ◽  
Fluid Management ◽  
Multiple Organ ◽  
Treatment Protocols ◽  
Hemodynamic Management ◽  
New Approach ◽  
Hemodynamic Optimization ◽  
The Individual ◽  
Sepsis And Septic Shock ◽  
Insight Into

Hemodynamic optimization remains the cornerstone of resuscitation in the treatment of sepsis and septic shock. Delay or inadequate management will inevitably lead to hypoperfusion, tissue hypoxia or edema, and fluid overload, leading eventually to multiple organ failure, seriously affecting outcomes. According to a large international survey (FENICE study), physicians frequently use inadequate indices to guide fluid management in intensive care units. Goal-directed and “restrictive” infusion strategies have been recommended by guidelines over “liberal” approaches for several years. Unfortunately, these “fixed regimen” treatment protocols neglect the patient’s individual needs, and what is shown to be beneficial for a given population may not be so for the individual patient. However, applying multimodal, contextualized, and personalized management could potentially overcome this problem. The aim of this review was to give an insight into the pathophysiological rationale and clinical application of this relatively new approach in the hemodynamic management of septic patients.

scholarly journals Simulation of Folding Kinetics for Aligned RNAs

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 347
Author(s):  
Jiabin Huang ◽  
Björn Voß
Keyword(s):  
Evolutionary Conservation ◽  
Folding Kinetics ◽  
New Approach ◽  
Computational Approaches ◽  
Reasonable Time ◽  
Valuable Method ◽  
Kinetics Of ◽  
Insight Into ◽  
Folding Space ◽  
Standing Problem

Studying the folding kinetics of an RNA can provide insight into its function and is thus a valuable method for RNA analyses. Computational approaches to the simulation of folding kinetics suffer from the exponentially large folding space that needs to be evaluated. Here, we present a new approach that combines structure abstraction with evolutionary conservation to restrict the analysis to common parts of folding spaces of related RNAs. The resulting algorithm can recapitulate the folding kinetics known for single RNAs and is able to analyse even long RNAs in reasonable time. Our program RNAliHiKinetics is the first algorithm for the simulation of consensus folding kinetics and addresses a long-standing problem in a new and unique way.

scholarly journals The Route for Ultra-High Recording Density Using Probe-Based Data Storage Device

NANO ◽  
2015 ◽  
Vol 10 (08) ◽  
pp. 1550118 ◽  
Author(s):  
Lei Wang ◽  
Jing Wen ◽  
CiHui Yang ◽  
Shan Gai ◽  
YuanXiu Peng
Keyword(s):  
Phase Change ◽  
Data Storage ◽  
Electrical Contact ◽  
Crystal Nucleation ◽  
Access Time ◽  
Storage Device ◽  
Electrical Contact Resistance ◽  
Low Energy Consumption ◽  
Modeling Techniques ◽  
Second Period

Phase-change probe memory using Ge2Sb2Te5 has been considered as one of the promising candidates as next-generation data storage device due to its ultra-high density, low energy consumption, short access time and long retention time. In order to utmostly mimic the practical setup, and thus fully explore the potential of phase-change probe memory for 10 Tbit/in2 target, some advanced modeling techniques that include threshold-switching, electrical contact resistance, thermal boundary resistance and crystal nucleation-growth, are introduced into the already-established electrothermal model to simulate the write and read performance of phase-change probe memory using an optimal media stack design. The resulting predictions clearly demonstrate the capability of phase-change probe memory to record 10 Tbit/in2 density under pico Joule energy within micro second period.

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