Three-dimensional contact stresses of a slick solid rubber tyre on a rigid surface

The main aim of this paper is to quantify the three-dimensional contact stresses imposed by a single slow-moving (or rolling) slick solid rubber tyre on a relatively rough contact surface, such as stiff asphalt concrete or airport concrete surfacing layers. The results indicated the tyre-contact patch of a slick solid rubber tyre to be of rectangular shape for a vertical tyre loading range between 20 kN and 100 kN. The rectangular tyre contact shape was confirmed with static paper prints, as well as an electronically measured contact patch with the stress-in-motion pad device. The study included load calibration using a mass load scale, and a stress-in-motion device. These were used with an existing full-scale accelerated pavement test device, referred to as the heavy vehicle simulator. In addition, simplistic multi-layer linear elastic modelling was used to quantify differences between stress and strain responses of two types of two relatively 'stiff' based pavements, such as an asphalt concrete base and Portland cement concrete base, on similar subbase and subgrade layers. Notable differences were obtained, which could potentially influence further detailed studies on the performance of full-scale slick solid rubber tyres on typical multi-layered pavements.

Tactile Interaction Sensor with Millimeter Sensing Acuity

In this article we report on a 3 × 3 mm tactile interaction sensor that is able to simultaneously detect pressure level, pressure distribution, and shear force direction. The sensor consists of multiple mechanical switches under a conducting diaphragm. An external stimulus is measured by the deflection of the diaphragm and the arrangement of mechanical switches, resulting in low noise, high reliability, and high uniformity. Our sensor is able to detect tactile forces as small as ~50 mgf along with the direction of the shear force. It also distinguishes whether there is a normal pressure during slip motion. We also succeed in detecting the contact shape and the contact motion, demonstrating potential applications in robotics and remote input interfaces. Since our sensor has a simple structure and its function depends only on sensor dimensions, not on an active sensing material, in comparison with previous tactile sensors, our sensor shows high uniformity and reliability for an array-type integration.

Effects of Contact Area and Contact Shape on Nonlinear Fluid Flow Properties of Fractures by Solving Navier-Stokes Equations

The influences of contact shape and contact area on nonlinear fluid flow properties through fractures are investigated by solving Navier-Stokes equations. The evolutions of nonlinear relationships between flow rate and hydraulic pressure drop, Forchheimer coefficients, nonlinear factor, critical hydraulic gradient, distributions of flow streamlines, and tracer flow paths at different times are systematically estimated. The results show that the nonlinear relationships between flow rate and hydraulic pressure drop can be well described by Forchheimer’s law, in which the nonlinear term coefficient b is approximately three orders of magnitude larger than the linear term coefficient a. The smaller contact area corresponds to smaller variations in many aspects such as flow rate, critical hydraulic gradient, flow streamlines, and tracer flow paths. The critical hydraulic gradient decreases with the increasing degree of contact shape variations while the contacts have the same mean area. The increase in hydraulic pressure drop can induce significant eddies and decrease the permeability and/or conductivity of fractures. However, the distributions of streamlines and tracer flow paths are not dramatically disturbed under a large hydraulic pressure drop.

Noise Filter Reducing Deformation in Digital Holography

A phase difference image using phase-shifting digital holography, which is applied for non-contact shape measurement, contains speckle noises and filtering to reduce them is inevitable for its application. We have developed a new filter which causes less deformation than commonly used filters.

Can past intergroup contact shape support for policies in a pandemic? Processes predicting endorsement of discriminatory Chinese restrictions during the COVID-19 crisis

A survey of 340 UK residents was conducted when the COVID-19 virus first reached the UK in February 2020. We measured past experiences of positive and negative intergroup contact with Chinese people as predictors of intergroup threat and emotions in the context of the pandemic; and how these processes in turn predicted support for discriminatory policies designed to restrict the freedom of Chinese people in the UK. We tested a novel threat-matching hypothesis which draws upon models of outgroup-specific social perception to predict that the emotional processes underlying contact effects will depend on the specific threat posed by the outgroup. In the present epidemiological context, Chinese people posed a salient threat to individuals’ physical health and welfare. Accordingly, we show that whilst intergroup contact predicted both fear and anger towards the outgroup, the indirect effect of contact on support for Chinese restriction policies via fear was significantly stronger than the indirect effect via anger. Our findings provide a more nuanced understanding of how specific threat and emotions drive intergroup contact effects, and offer important insights for efforts to maintain positive intergroup relations in the face of the crisis.

Numerical Procedure for Non-Hertzian Wheel-Rail Contact Model Integrated in Quasi-Steady Railway Vehicle Motion Solver

Although the Hertzian contact theory is widely utilized in railway vehicle simulations with new wheel and rail profiles, the Hertzian contact assumptions would lead to inaccurate contact prediction for severely worn wheel and rail profiles due to their geometric conformity, causing non-elliptical contact shapes as well as pressure distribution. For this reason, various non-Hertzian contact models have been studied for use in vehicle dynamics simulations. Among others, a method proposed by Piotrowski and Kik has gained acceptance in predicting non-elliptical wheel-rail contact for vehicle dynamics simulations. Despite the elegant formulation and its accuracy, detailed online geometric calculation for non-elliptical contact shape is required for all the contact patches at every iteration, along with iterative evaluation of the force-deflection relationship. It leads to computation burdens for use in long-distance vehicle simulations. Therefore, in this study, an off-line based numerical procedure for non-Hertzian contact model is developed and integrated in the quasi-steady railway vehicle motion solver.

Commemoration Is a Constant Struggle

Readers may be familiar with Civil Rights Movement adage: “freedom is a constant struggle.” This concluding chapter demonstrates how commemoration is a constant struggle, highlighting the decades-long efforts to institutionalize the collective memory of racial violence in the United States. Thus, this chapter argues that attention to commemorative outcomes should be a critical concern of collective memory research, concerns that have remained largely unexplored. The chapter further suggests that it is most advantageous to conceptualize commemorations and memory movements as iterative, a feedback loop in which movements produce commemorations and commemorations produce movements. It then highlights the process of commemorating difficult pasts, arguing that the meso-level interactional dynamics such as intergroup contact shape possibilities for commemorative outcomes. In this way, the social psychology of racial identity and intergroup contact provide important insights for local memory activists and racial reconciliation practitioners more broadly.

Noise Filter for Surface Shape Measurement in Digital Holography

Phase difference image using phase-shifting digital holography is one of the prospective methods for non-contact shape measurement. For the application, filtering of the obtained image is needed to reduce the speckle noise. Conventional filter, e.g. moving average filter, causes loss of the shape information especially around the region with high steepness. To solve this problem novel filter has been developed that kept steepness of the shape in noise reduction. The filtered data were compared with conventionally filtering ones and the former was closer to the data observed by a laser measuring microscope.