Study on the accelerated-point distribution of floating fibers in the drafting zone

The motion of floating fibers in the drafting zone has a significant effect on the sliver quality after drafting. In this study, the distribution of the accelerated point of floating fibers in the drafting area was simulated based on the distribution of fibers and frictional forces during the drafting process. The simulated results denoted that the acceleration distribution of the floating fibers was more concentrated and closer to the front roller as the drafting ratio increases. The distributions of accelerated points of the floating fibers became more and more decentralized and further away from the front roller as the gauge length grew when the other parameters remained constant. In the simulation, the frictional forces of the other floating fibers moving at high velocity and low velocity and the actual contact relationships of fibers in the drafting zone were taken into consideration. Moreover, whether the fiber lengths are identical or not, the simulated accelerated-point distributions of the floating fibers were demonstrated to conform more to the actual values compared to other models. Hence, the developed model can offer effective reference from the point of view of the distribution of accelerated points in order to realize the simulation of roller drafting.

Development of a rheological model of stress relaxation in the structure of an oil film on the friction surface with fullerene additives

A rheological model of stress relaxation in a thin lubricant film, which is formed on the friction surface under the influence of the force field of the friction surface in the presence of fullerene compositions in lubricants, was developed. Analysis of the model made it possible to establish that the existence of elastic or viscous properties in surface structures depends on the ratio of two parameters. This is the time of stress relaxation in the structure on spots of actual contact and the duration of stress action on these spots, which is termed the lifetime of an actual contact spot. It was shown that an increase in the sliding rate reduces the time of relaxation of stresses in the surface structure. This is due to the destruction of aggregates in the structure of gel and the appearance of rotational movements of separate units ‒ flocs. An increase in the load on the tribosystem significantly increases the value of relaxation time. This is due to squeezing the viscous component out of the structure of a surface film. It was established that if the relaxation time exceeds the duration of actions of stresses on actual contact spots, the structure of a surface film behaves like an elastic solid. Conversely, if relaxation time becomes shorter than the duration of stress action, the film behaves like a viscous medium. Theoretically, it was shown that in the range of sliding and loading rates, when a film behaves like an elastic solid, a decrease in stresses on actual contact spots does not exceed the values of 1.1‒22.8 %. This property provides the bearing capacity of a film. The development of the model will make it possible to simulate elastic and viscous properties of "stitched" structures and substantiate the rational concentrations of additives to lubricants, as well as the ranges of their use.

Social Distancing Detection using Deep Learning

The continuous COVID-19 Covid episode has caused a worldwide calamity with its dangerous spreading. due to the shortfall of successful healing specialists and therefore the lack of vaccinations against the infection, populace weakness increments. within the current circumstance, as there aren't any antibodies accessible; hence, social removing is believed to be a sufficient precautionary measure (standard) against the spread of the pandemic infection. the risks of infection spread may be limited by keeping aloof from actual contact among individuals. the rationale for this work is, thusly, to administer a profound learning stage to social distance is additionally executed to create the exactness of the model. Thusly, the popularity calculation utilizes a pre-prepared calculation that's related to an additional prepared the distinguished jumping box centroid's pairwise distances of people are resolved. To appraise social distance infringement between individuals, we utilized an estimation of actual distance to pixel and set a grip. An infringement limit is ready up to assess whether the space esteem breaks the bottom social distance edge. Analyses are done on various video arrangements to check the proficiency of the model. Discoveries show that the created system effectively recognizes folks that walk excessively close and penetrates/abuses social seperation; also, the trade collecting approach upholds the general efficiency of the model. The precision of 91% and 96% achieved by the acknowledgment model without and with move learning, independently. The accompanying precision of the model is 94%

EFFECT OF RATIO OF MATERIAL HARDNESSES, AVERAGE PRESSURE AND ROUGHNESS PARAMETERS ON ACTUAL CONTACT AREA OF ASSEMBLED SURFACES

The paper describes the influence of various factors, including the ratio of hardness, average pressure, radius of microasperities of the surface, affecting the value of the actual contact area of rough surfaces of flat parts mated in fixed joints. The study was carried out using the dependences obtained by the authors describing the elastic-plastic contact of rough surfaces.

MECHANICS OF CONTACT IN THE GRINDING OF STEELS

The article is devoted to the consideration of the issues of contact interaction of a diamond grinding tool with the surface of the part. According to the research results, the actual contact areas were obtained, taking into account the sum of the actual contact areas of the touching bodies, through which the pressing force of the grinding wheel to the treated surface is transmitted, with elastic, plastic and elastic-plastic contacts. The obtained analytical dependences for calculating the geometric parameters of the contact of a diamond face tool with the workpiece surface being machined, allowing to describe, predict and control the power and resistance characteristics of the process on the processing conditions

A Shear Strength Model for a Subsidence Backfill Body Based on Adhesion Friction Theory

Proper determination of the shear strength of the backfill body used to fill the subsidence is the basis for subsidence restoration and the stability analysis of materials. This study developed a shear strength calculation model for the backfill body by introducing adhesive friction theory into the shear strength analysis. A direct shear test was performed in the laboratory to verify the proposed method. Test results suggested that the shear strength calculation method based on adhesive friction theory can calculate the variation in the actual contact area between grains in the tested samples undergoing shearing and estimate the peak shear strength. The actual contact area was divided into two components, namely, adhesive contact area Arm and contact area reduction caused by shear displacement, which exhibited a maximum at Armax. The shear strength values calculated by this method were smaller than laboratory values, and their differences increased with the rock proportion in the backfill body. The differences between the theoretical and experimental values of shear strength increased with the rock grain size. The results of theoretical calculation, combined with the results of laboratory experiments, can provide support for the proper determination of shear strength of the backfill body.

When Does Imagined Contact Reduce Prejudice?

Imagined contact has been argued to reduce prejudice. Although extant research supports this argument, replication attempts have been unsuccessful. To resolve conflicting evidence from previous studies, this study examined the effect of imagined contact on explicit and implicit prejudice against Kurds and Syrians in Turkey. Using data from 335 Turkish undergraduate students, the moderating role of ethnic and national identification in the imagined contact effect was tested. Results indicated that imagined contact did not reduce prejudice, and in-group identification did not have a moderating effect, even after controlling for actual contact. These findings call for a theoretical refinement to the imagined contact hypothesis and emphasize the need for further research to advance our understanding of when imagined contact works.

EHL Analysis of Spiral Bevel Gear Pairs considering the Contact Point Migration due to Deformation under Load

The actual contact point of a spiral bevel gear pair deviates from the theoretical contact point due to the gear deformation caused by the load. However, changes in meshing characteristics due to the migration of contact points are often ignored in previous studies on the elastohydrodynamic lubrication (EHL) analysis of spiral bevel gears. The purpose of this article is to analyze the impact of contact point migration on the results of EHL analysis. Loaded tooth contact analysis (LTCA) based on the finite element method is applied to determine the loaded contact point of the meshing tooth pair. Then, the osculating paraboloids at this point are extracted from the gear tooth surface geometry. The geometric and kinematic parameters for EHL simulation are determined according to the differential geometry theory. Numerical solutions to the Newtonian isothermal EHL of a spiral bevel gear pair at the migrated and theoretical contact points are compared to quantify the error involved in neglecting the contact point adjustment. The results show that under heavy-loaded conditions, the actual contact point of the deformed gear pair at a given pinion (gear) roll angle is different from the theoretical contact point considerably, and so do the meshing parameters. EHL analysis of spiral bevel gears under significant load using theoretical meshing parameters will result in obvious errors, especially in the prediction of film thickness.

Role of Surface Roughness in the Interlayer Boundary Formation during Manufacturing of Clad Metal Composites

In the present research work, the role of surface roughness in the interlayer boundary formation during manufacturing of clad metal composites was analyzed. Process of interlayer boundary formation was described through mathematical and computer simulation. The importance of taking into account not only arithmetical mean roughness Ra or ten-point mean roughness Rz, but also Rz/S ratio (where S – mean spacing of adjacent peaks) is shown, because this relation affects the length of actual contact between dissimilar materials. As the result of mathematical and computer simulation, dependence of the length of actual contact between dissimilar materials on Rz/S ratio and semi-angle of the ridge vertex was obtained.