Particle entrapment in elliptical, elastohydrodynamic, rough contacts and the influence of intermolecular (van der Waals) forces

2021 ◽  
pp. 135065012110001
Author(s):  
George K Nikas
Keyword(s):  
Parametric Analysis ◽  
Van Der Waals ◽  
Intermolecular Forces ◽  
Intermolecular Force ◽  
Performance Indices ◽  
Roughness Effects ◽  
Particle Entrapment ◽  
And Performance ◽  
Particle Force ◽  
Lubricant Viscosity

The entrapment/rejection process of spherical, rigid microparticles in elliptical, rough elastohydrodynamic contacts is modelled. An earlier model of the author is extended to include van der Waals intermolecular forces, in addition to mechanical (reaction and friction) and fluid–particle forces. Surface roughness effects are also introduced in terms of the intermolecular force formulation and in the microscale friction (particle–asperity) sub-model. Possibilities related to particle entry into a contact are quantified by weight factors and performance indices. A total entrapment index is defined and linked to the probability of particle entrapment. A parametric analysis investigates the effect of the intermolecular particle force on the entrapment probability by varying the contact load, lubricant viscosity, elastic modulus of the contacting solids, contact velocity and the macroscopic (Coulomb) coefficient of friction.

scholarly journals Particle Entrapment in Line Elastohydrodynamic Contacts and the Influence of Intermolecular (van der Waals) Forces

Lubricants ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 60
Author(s):  
George K. Nikas
Keyword(s):  
Surface Roughness ◽  
Parametric Analysis ◽  
Van Der Waals ◽  
Surface Damage ◽  
Intermolecular Force ◽  
Roughness Effects ◽  
Fluid Forces ◽  
Micro Particles ◽  
Particle Entrapment ◽  
Complete Set

A metallic particle passing through concentrated rolling-sliding contacts is often linked to surface damage for particles larger than the available gap. At the instant of particle pinching, force balancing dictates particle entrapment and passing through the contact or rejection. It is vital to include all major forces in this process. This study revisits the analytical entrapment model previously published by the author for spherical micro-particles by incorporating a force so far overlooked in related studies, namely the van der Waals intermolecular force and, additionally, surface roughness effects. In conjunction with particle mechanical and fluid forces, this provides an almost complete set to use for correct force balancing. A parametric analysis shows the effect of several geometrical, mechanical, rheological, and surface parameters on spherical particle entrapment and reveals the significance of the van der Waals force for particles smaller than about 5–10 μm in diameter.

Parametric analysis and performance of laser cutting on strenx steel

2020 ◽  
Author(s):  
K. Muralidharan ◽  
S. Shalini Packiam Kamala ◽  
D. Alankrutha ◽  
K. Bhanu Prakash ◽  
Ram Subbiah ◽  
...  
Keyword(s):  
Laser Cutting ◽  
Parametric Analysis ◽  
And Performance

scholarly journals Sectorization for Water Distribution Systems with Multiple Sources: A Performance Indices Comparison

Water ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 131
Author(s):  
Jezabel D. Bianchotti ◽  
Melina Denardi ◽  
Mario Castro-Gama ◽  
Gabriel D. Puccini
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Distribution Networks ◽  
Performance Criteria ◽  
Performance Indices ◽  
Multiple Sources ◽  
Multiobjective Problems ◽  
Open Questions ◽  
Minimum Number ◽  
And Performance

Sectorization is an effective technique for reducing the complexities of analyzing and managing of water systems. The resulting sectors, called district metering areas (DMAs), are expected to meet some requirements and performance criteria such as minimum number of intervention, pressure uniformity, similarity of demands, water quality and number of districts. An efficient methodology to achieve all these requirements together and the proper choice of a criteria governing the sectorization is one of the open questions about optimal DMAs design. This question is addressed in this research by highlighting the advantages of three different criteria when applied to real-word water distribution networks (WDNs). To this, here it is presented a two-stage approach for optimal design of DMAs. The first stage, the clustering of the system, is based on a Louvain-type greedy algorithm for the generalized modularity maximization. The second stage, the physical dividing of the system, is stated as a two-objective optimization problem that utilises the SMOSA version of simulated annealing for multiobjective problems. One objective is the number of isolation valves whereas for the second objective three different performance indices (PIs) are analyzed and compared: (a) standard deviation, (b) Gini coefficient and (c) loss of resilience. The methodology is applied to two real case studies where the first two PIs are optimized to address similar demands among DMAs. The results demonstrate that the proposed method is effective for sectorization into independent DMAs with similar demands. Surprisingly, it found that for the real studied systems, loss of resilience achieves better performance for each district in terms of pressure uniformity and demand similarity than the other two specific performance criteria.

scholarly journals Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2363
Author(s):  
Rodrigo Dlugosz da Silva ◽  
Marcelo Augusto de Aguiar e Silva ◽  
Marcelo Giovanetti Canteri ◽  
Juliandra Rodrigues Rosisca ◽  
Nilson Aparecido Vieira Junior
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Global Radiation ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Performance Indices ◽  
Excellent Performance ◽  
Study Region ◽  
Temperature Radiation ◽  
And Performance

Aiming at assessing the performance of alternative methods to Penman-Monteith FAO56 for estimating the reference evapotranspiration (ETo) for Londrina, Paraná, Brazil, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tanner-Pelton, Jensen-Haise, Makkink, modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, Linacre, Blaney-Morin, Romanenko, Hargreaves (1974), McCloud, Camargo, Hamon, Kharrufa, McGuiness-Bordne, and Blaney-Criddle were compared to that standard method recommended by FAO. The estimations were correlated by linear regression and assessed by using the Person’s correlation coefficient (r), concordance index (d), and performance index (c) using a set of meteorological data of approximately 40 years. The methods modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, and Linacre should be avoided, as they did not present excellent results. The methods McCloud, Camargo, Hamon, Kharrufa, McGuinness-Bordne, Blaney-Criddle, Hargreaves (1974), Romanenko, and Blaney-Morin were classified as very bad, not being recommended. In contrast, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tenner-Pelton, Jensen-Haise, and Makkink presented excellent performance indices and can be applied in the study region.

scholarly journals Reference evapotranspiration for Londrina, Paraná, Brazil: performance of different estimation methods

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2363
Author(s):  
Rodrigo Dlugosz da Silva ◽  
Marcelo Augusto de Aguiar e Silva ◽  
Marcelo Giovanetti Canteri ◽  
Juliandra Rodrigues Rosisca ◽  
Nilson Aparecido Vieira Junior
Keyword(s):  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Global Radiation ◽  
Alternative Methods ◽  
Estimation Methods ◽  
Performance Indices ◽  
Excellent Performance ◽  
Study Region ◽  
Temperature Radiation ◽  
And Performance

Aiming at assessing the performance of alternative methods to Penman-Monteith FAO56 for estimating the reference evapotranspiration (ETo) for Londrina, Paraná, Brazil, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tanner-Pelton, Jensen-Haise, Makkink, modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, Linacre, Blaney-Morin, Romanenko, Hargreaves (1974), McCloud, Camargo, Hamon, Kharrufa, McGuiness-Bordne, and Blaney-Criddle were compared to that standard method recommended by FAO. The estimations were correlated by linear regression and assessed by using the Person’s correlation coefficient (r), concordance index (d), and performance index (c) using a set of meteorological data of approximately 40 years. The methods modified Hargreaves, Stephens-Stewart, Abtew, global radiation, Ivanov, Lungeon, Hargreaves-Samani (1985), Benavides-Lopez, original Penman, and Linacre should be avoided, as they did not present excellent results. The methods McCloud, Camargo, Hamon, Kharrufa, McGuinness-Bordne, Blaney-Criddle, Hargreaves (1974), Romanenko, and Blaney-Morin were classified as very bad, not being recommended. In contrast, the methods temperature radiation, Hicks-Hess, Hargreaves-Samani (1982), Turc, Priestley-Taylor, Tenner-Pelton, Jensen-Haise, and Makkink presented excellent performance indices and can be applied in the study region.

Wrench capabilities of planar parallel manipulators. Part I: Wrench polytopes and performance indices

Robotica ◽  
2008 ◽  
Vol 26 (6) ◽  
pp. 791-802 ◽  
Author(s):  
Flavio Firmani ◽  
Alp Zibil ◽  
Scott B. Nokleby ◽  
Ron P. Podhorodeski
Keyword(s):  
Parallel Manipulators ◽  
Joint Space ◽  
Linear Mapping ◽  
Redundant Manipulators ◽  
Task Space ◽  
Performance Indices ◽  
Study Case ◽  
And Performance ◽  
Planar Parallel Manipulators

SUMMARYThis paper is organized in two parts. In Part I, the wrench polytope concept is presented and wrench performance indices are introduced for planar parallel manipulators (PPMs). In Part II, the concept of wrench capabilities is extended to redundant manipulators and the wrench workspace of different PPMs is analyzed. The end-effector of a PPM is subject to the interaction of forces and moments. Wrench capabilities represent the maximum forces and moments that can be applied or sustained by the manipulator. The wrench capabilities of PPMs are determined by a linear mapping of the actuator output capabilities from the joint space to the task space. The analysis is based upon properly adjusting the actuator outputs to their extreme capabilities. The linear mapping results in a wrench polytope. It is shown that for non-redundant PPMs, one actuator output capability constrains the maximum wrench that can be applied (or sustained) with a plane in the wrench space yielding a facet of the polytope. Herein, the determination of wrench performance indices is presented without the expensive task of generating polytopes. Six study cases are presented and performance indices are derived for each study case.

Physiology and bromatology of Oryctolagus cunicullus L. 1758 fed browse legume with enzyme levels

Agro-Science ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 45-50
Author(s):  
A.M. Ogungbesan ◽  
O.E. Fasina ◽  
E.O. Alagbe ◽  
O.O. Eniolorunda
Keyword(s):  
Crude Protein ◽  
Dry Matter ◽  
Treatment Effects ◽  
Gliricidia Sepium ◽  
Performance Indices ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
And Performance ◽  
Nutritional Benefits ◽  
Dietary Treatments

The objective of this experiment was to determine the effects of feeding rabbits with Maxigrain® (M) enzyme supplemented Gliricidia sepium leaf meal (GLM) on their physiology, performance characteristics, and nutrients digestibility. Twenty weaned rabbits of mixed sexes, 5-6 weeks old, were randomly allotted to five dietary treatments including 0 g M which was soybean without M (control) and GLM supplemented with M at 50, 100, 150 and 200 g M per kilogramme of GLM. There were four rabbits per treatment and one rabbit as replicate in a completely randomized design. There were no significant (p > 0.05) treatment effects in all physiological and performance indices as well as those of crude fat, fibre and NFE digestibilities. There were variations (p < 0.05) due to the treatment effects on dry matter, crude protein and ash digestiblities. This implies that the feeding of soft faeces directly from the caecum called coprophagy mechanism in rabbits has its concomitant nutritional benefits. This advantageous benefit can enable rabbit to effectively and efficiently utilize forage or forage-based diet with or without enzyme supplementation.

scholarly journals Variational Calculus Approach to Optimal Interception Task of a Ballistic Missile in 1D and 2D Cases

Algorithms ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 148
Author(s):  
Dariusz Horla
Keyword(s):  
Parametric Analysis ◽  
Variational Calculus ◽  
Open Loop ◽  
Ballistic Missile ◽  
Control Law ◽  
Open Loop Control ◽  
Performance Indices ◽  
Lagrange Equations ◽  
Loop Control ◽  
Conservation Of Momentum

The paper presents the application of variational calculus to achieve the optimal design of the open-loop control law in the process of anti-ballistic missile interception task. It presents the analytical results in the form of appropriate Euler–Lagrange equations for three different performance indices, with a simple model of the rocket and the missile, based on the conservation of momentum principle. It also presents the software program enabling rapid simulation of the interception process with selected parameters, parametric analysis, as well as easy potential modification by other researchers, as it is written in open code as m-function of Matlab.

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