scholarly journals Shearing-induced contact pattern formation in hydrogels sliding in polymer solution

Soft Matter ◽  
2019 ◽  
Vol 15 (9) ◽  
pp. 1953-1959 ◽  
Author(s):  
Shintaro Yashima ◽  
Satoshi Hirayama ◽  
Takayuki Kurokawa ◽  
Thomas Salez ◽  
Haruna Takefuji ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Polymer Solution ◽  
Glass Surface ◽  
Contact Pattern ◽  
Contact Patterns ◽  
Sodium Hyaluronan

Hydrogels during rotational shearing on a glass surface in concentrated sodium hyaluronan solution make various dynamic periodical circumferential contact patterns.

scholarly journals Virulence evolution of a parasite infecting male and female hosts

2017 ◽  
Author(s):  
Alison M. Wardlaw ◽  
Aneil F. Agrawal
Keyword(s):  
Death Rate ◽  
Host Population ◽  
Reproductive Value ◽  
Contact Pattern ◽  
Male And Female ◽  
Virulence Evolution ◽  
Host Type ◽  
Contact Patterns ◽  
Exploitation Rate ◽  
Evolutionarily Stable

AbstractParasites experience different tradeoffs between transmission and virulence in male and female hosts if the sexes vary in life history or disease-related traits. We determine the evolutionarily stable levels of exploitation by pathogens under two scenarios: an unconstrained pathogen that expresses different exploitation rates within each host type as well as a pathogen constrained to express the same exploitation rate in each sex. We show that an unconstrained horizontally-transmitted parasite evolves to express the same sex-specific exploitation rate within each sex as it would in a host population composed entirely of hosts with that sex’s resistance and intrinsic death rate. In contrast, the ESS exploitation rate of a constrained pathogen is affected by sex-differences in susceptibility and non-random contact patterns between host types that differ in resistance. As the amount of within-sex transmission increases, the ESS shifts closer to the optimum trait value in the more susceptible sex. Allowing for some degree of vertical transmission, the exploitation rate expressed in females (but not males) changes with contact pattern even in unconstrained pathogens. Differences in contact pattern and susceptibility play an important role in determining the ESS exploitation rate by shifting the reproductive value of each host type.

Drying Mediated Pattern Formation in a Capillary-Held Organometallic Polymer Solution

2005 ◽  
Vol 17 (25) ◽  
pp. 6223-6226 ◽  
Author(s):  
Suck Won Hong ◽  
Jun Xu ◽  
Jianfeng Xia ◽  
Zhiqun Lin ◽  
Feng Qiu ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Polymer Solution ◽  
Organometallic Polymer

Magnitude and Spatial Distribution of Impact Intensity Under the Foot Relates to Initial Foot Contact Pattern

2017 ◽  
Vol 33 (6) ◽  
pp. 431-436 ◽  
Author(s):  
Bastiaan Breine ◽  
Philippe Malcolm ◽  
Veerle Segers ◽  
Joeri Gerlo ◽  
Rud Derie ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Loading Rate ◽  
Ground Reaction Forces ◽  
Contact Pattern ◽  
Intensity Measure ◽  
Foot Kinematics ◽  
Contact Patterns ◽  
Reaction Forces ◽  
Local Impact ◽  
The Impact

In running, foot contact patterns (rear-, mid-, or forefoot contact) influence impact intensity and initial ankle and foot kinematics. The aim of the study was to compare impact intensity and its spatial distribution under the foot between different foot contact patterns. Forty-nine subjects ran at 3.2 m·s−1 over a level runway while ground reaction forces (GRF) and shoe-surface pressures were recorded and foot contact pattern was determined. A 4-zone footmask (forefoot, midfoot, medial and lateral rearfoot) assessed the spatial distribution of the vertical GRF under the foot. We calculated peak vertical instantaneous loading rate of the GRF (VILR) per foot zone as the impact intensity measure. Midfoot contact patterns were shown to have the lowest, and atypical rearfoot contact patterns the highest impact intensities, respectively. The greatest local impact intensity was mainly situated under the rear- and midfoot for the typical rearfoot contact patterns, under the midfoot for the atypical rearfoot contact patterns, and under the mid- and forefoot for the midfoot contact patterns. These findings indicate that different foot contact patterns could benefit from cushioning in different shoe zones.

Evaluation System of Tooth Contact Patterns of Hypoid Gears Using Artificial Intelligence

2012 ◽  
Author(s):  
Morimasa Nakamura ◽  
Keisuke Kojima ◽  
Ichiro Moriwaki
Keyword(s):  
Neural Network ◽  
Artificial Intelligence ◽  
Evaluation System ◽  
Gear Pair ◽  
Contact Pattern ◽  
Hypoid Gear ◽  
Tooth Contact ◽  
Contact Patterns ◽  
The Neural Network ◽  
Hypoid Gear Pairs

Tooth contact inspection is one of the most common methods for checking qualities of hypoid gear pairs. A change in machine setting parameters for cutting and lapping processes of a hypoid gear pair enables a tooth contact pattern of a hypoid gear pair to be varied. The deviation of the pattern from the target one is represented by a grade point. In the inspection, the qualities of hypoid gear pairs are usually classified into only two grades; OK or NG. However, in order to conduct a follow-up survey on problems of the products and to be useful to be trouble shooting tasks of the end products, finer classifications and more quantitative evaluations of tooth contact patterns could be effective. Such approaches have been tried, however, only experienced and well-trained technicians for the inspection of hypoid gear pairs can determine the point of each tooth contact pattern. And it is difficult to make this evaluation method automatic. To overcome this problem, an application of artificial intelligence system must be useful. The present paper describes a computer evaluation system using the neural network, which is a kind of the artificial intelligence systems, for tooth contact patterns of hypoid gear pairs which can evaluate the results of the inspections instead of experienced hypoid gear technicians. This system with the neural network has a capability to learn relationships between evaluation grade points of tooth contact patterns given by the hypoid gear technicians and graphics of tooth contact patterns of hypoid gear pairs. Moreover, it can return the evaluation grade points when a tooth contact pattern is input into the system. The evaluation performance of the developed system was discussed. And a quality of normative tooth contact patterns, which were used as the teacher signals for training the neural network system, greatly affected its performance. The comparison of evaluated grade points obtained from developed system with the technician’s ones showed that the correct answer ratio obtained from the developed system was about 90% in the best case.

Robust Optimization of the Loaded Contact Pattern in Hypoid Gears With Uncertain Misalignments

2009 ◽  
Author(s):  
M. Gabiccini ◽  
A. Bracci ◽  
M. Guiggiani
Keyword(s):  
Optimization Problems ◽  
Optimization Procedure ◽  
Target Area ◽  
Contact Pattern ◽  
Unified Framework ◽  
Hypoid Gears ◽  
Contact Patterns ◽  
Unconstrained Nonlinear Optimization ◽  
The One ◽  
Micro Topography

This paper presents an automatic procedure to optimize the loaded tooth contact pattern of face-milled hypoid gears with misalignments varying within prescribed ranges. A two-step approach is proposed to solve the problem: in the first step, the pinion tooth micro-topography is automatically modified to bring the perturbed contact patterns (as the assembly errors are varied within the tolerance limits) match a target area of the tooth, while keeping them off the edges; in the second step, a subset of the machine-tool settings is identified to obtain the required topography modifications. Both steps are formulated and solved as unconstrained nonlinear optimization problems. While the general methodology is similar to the one recently proposed by the same authors for the optimization at nominal conditions, here the robustness issues with respect to misalignment variations are considered and directly included in the optimization procedure: no a posteriori check for robustness is therefore required. Numerical tests show that nominally satisfactory and globally robust hypoid pairs can be designed by a direct process and within a unified framework, thus avoiding tiresome trial-and-error loops.

scholarly journals Examination of the contact pattern of rolling surfaces

2019 ◽  
Vol 9 (2) ◽  
pp. 38-43
Author(s):  
Ferenc Sarka
Keyword(s):  
Operating Conditions ◽  
Contact Pattern ◽  
Rolling Bearings ◽  
Contact Patterns ◽  
Potential Applications ◽  
Gear Drives ◽  
Shape And Size

This article provides a brief summary of the potential applications of contact pattern examinations. The examination of contact pattern is a frequently used test for gear drives, rolling bearings and checking support rollers. It is used on gear drives and support rollers to test operating conditions, whereas in the case of rolling bearings the cause of the failure has already been identified. The chapters mention the types of contact patterns, the shape and size of contact patterns. This article is an introduction to a multi-part article series that presents the computerbased capabilities of contact pattern examination.

scholarly journals Social contact patterns can buffer costs of forgetting in the evolution of cooperation

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180407 ◽  
Author(s):  
Jeffrey R. Stevens ◽  
Jan K. Woike ◽  
Lael J. Schooler ◽  
Stefan Lindner ◽  
Thorsten Pachur
Keyword(s):  
Social Contact ◽  
Evolution Of Cooperation ◽  
Contact Pattern ◽  
Memory Errors ◽  
Memory Error ◽  
Pattern Type ◽  
Cognitive Limitations ◽  
Contact Patterns ◽  
Simplifying Assumptions ◽  
Evolutionary Simulations

Analyses of the evolution of cooperation often rely on two simplifying assumptions: (i) individuals interact equally frequently with all social network members and (ii) they accurately remember each partner's past cooperation or defection. Here, we examine how more realistic, skewed patterns of contact—in which individuals interact primarily with only a subset of their network's members—influence cooperation. In addition, we test whether skewed contact patterns can counteract the decrease in cooperation caused by memory errors (i.e. forgetting). Finally, we compare two types of memory error that vary in whether forgotten interactions are replaced with random actions or with actions from previous encounters. We use evolutionary simulations of repeated prisoner's dilemma games that vary agents' contact patterns, forgetting rates and types of memory error. We find that highly skewed contact patterns foster cooperation and also buffer the detrimental effects of forgetting. The type of memory error used also influences cooperation rates. Our findings reveal previously neglected but important roles of contact pattern, type of memory error and the interaction of contact pattern and memory on cooperation. Although cognitive limitations may constrain the evolution of cooperation, social contact patterns can counteract some of these constraints.

Optimized Bearing Ellipses of Hypoid Gears1

2003 ◽  
Vol 125 (4) ◽  
pp. 739-745 ◽  
Author(s):  
J. Achtmann ◽  
G. Ba¨r
Keyword(s):  
Influence Function ◽  
Gear Tooth ◽  
Target Pair ◽  
Evaluation Function ◽  
Contact Pattern ◽  
Hypoid Gear ◽  
Tooth Contact ◽  
Gear Drive ◽  
Contact Patterns ◽  
Best Fit

For given machine tool settings of a universal hypoid gear generator, the tooth contact patterns are computed for the coast and drive side of a hypoid gear drive. Each contact pattern is replaced by a determined tooth-bearing ellipse. The position, shape, and inclination of each bearing ellipse is calculated. By the help of these data, an influence function is designed that describes the influence of supplemental kinematic flank correction motions (modified motions) on the gear-tooth contact. Examples show the influence of helical motion and modified roll. An evaluation function permits the calculation of modified motions which improve the tooth contact either at coast and drive side simultaneously, or only at one of the sides. For a given pair of start-bearing ellipses at coast and drive side, and for given importance weights to the sides, we describe how modified motions can be computed that best fit a given target pair of bearing ellipses.

Robust Optimization of the Loaded Contact Pattern in Hypoid Gears With Uncertain Misalignments

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. Gabiccini ◽  
A. Bracci ◽  
M. Guiggiani
Keyword(s):  
Optimization Problems ◽  
Optimization Procedure ◽  
Target Area ◽  
Contact Pattern ◽  
Trial And Error ◽  
Unified Framework ◽  
Hypoid Gears ◽  
Contact Patterns ◽  
Unconstrained Nonlinear Optimization ◽  
The One

This paper presents an automatic procedure to optimize the loaded tooth contact pattern of face-milled hypoid gears with misalignments varying within prescribed ranges. A two-step approach is proposed to solve the problem: in the first step, the pinion tooth microtopography is automatically modified to bring the perturbed contact patterns (as the assembly errors are varied within the tolerance limits) match a target area of the tooth while keeping them off the edges; in the second step, a subset of the machine-tool settings is identified to obtain the required topography modifications. Both steps are formulated and solved as unconstrained nonlinear optimization problems. While the general methodology is similar to the one recently proposed by the same authors for the optimization at nominal conditions, here, the robustness issues with respect to misalignment variations are considered and directly included in the optimization procedure: no a posteriori check for robustness is therefore required. Numerical tests show that nominally satisfactory and globally robust hypoid pairs can be designed by a direct process and within a unified framework, thus avoiding tiresome trial-and-error loops.

scholarly journals Reflections from COVID-19 Pandemic: Contact Diary for Assessing Social Contact Patterns in Nepal

2020 ◽  
Vol 18 (2) ◽  
pp. 340-341
Author(s):  
Niraj Shrestha ◽  
Achyut Raj Pandey ◽  
Mirak Raj Angdembe
Keyword(s):  
Public Health ◽  
Infectious Disease ◽  
Resource Availability ◽  
Disease Transmission ◽  
Social Contact ◽  
Health Interventions ◽  
Contact Pattern ◽  
Public Health Interventions ◽  
Infectious Disease Transmission ◽  
Contact Patterns

Management of COVID-19 in Nepal will certainly benefit from the experiences of other countries. However, they are less likely to be suitable for Nepal both in terms of context and resource availability. Social contact pattern studies have shown that understanding the nature of human-to-human contacts can help describe the dynamics of infectious disease transmission. The findings of such studies will help the country prepare itself for future outbreaks, inform mathematically modelling and public health interventions that match domestic capabilities. Methods such as self-reported contact diary can be used to conduct such studies following a feasibility study. Keywords: Contact diary;COVID-19; disease transmission; social contact pattern.

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