DIAGNOSTICS OF WORKPIECE SURFACE CONDITION BASED ON CUTTING TOOL VIBRATIONS DURING MACHINING

The paper presents functional relationships between surface geometry parameters, feed and vibrations level in the radial direction of the workpiece. Time characteristics of the acceleration of cutting tool vibration registered during C45 steel and stainless steel machining for separate axes (X, Y, Z) were presented as a function of feedrate f. During the tests surface geometric accuracy assessment was performed and 3D surface roughness parameters were determined. The Sz parameter was selected for the analysis, which was then collated with RMS vibration acceleration and feedrate f. The Sz parameter indirectly provides information on peak to valley height and is characterised by high generalising potential i.e. it is highly correlated to other surface and volume parameters of surface roughness. Test results presented in this paper may constitute a valuable source of information considering the influence of vibrations on geometric accuracy of elements for engineers designing technological processes

IMPACT OF FRICTION COEFFICIENT VARIATION ON TEMPERATURE FIELD IN ROTARY FRICTION WELDING OF METALS – FEM STUDY

A mathematical model is presented for investigating the temperature field caused by the rotary friction welding of dissimilar metals. For this purpose, an axisymmetric, nonlinear, boundary value problem of heat conduction is formulated with allowance for the frictional heating of two cylindrical specimens of finite length made of Al 6061 aluminium alloy and 304 stainless steel. The thermo-physical properties of materials change with increasing temperature. It was assumed that the coefficient of friction does not depend on the temperature. The mechanism of heat generation due to friction on the contact surface with the temperature field of samples is considered. The boundary problem of heat conduction was reduced to the set of nonlinear ordinary differential equations at time t relative to the values of temperature T at the finite elements nodes. The numerical solution of the problem was obtained with the inverse 2nd order differentiation method implemented in COMSOL FEM system (finite element method), with time step ∆t=0.1 (s). The influence of various values of friction coefficient is presented

PREDICTIVE TOOLS AS PART OF DECISSION AIDING PROCESSES AT THE AIRPORT – THE CASE OF FACEBOOK PROPHET LIBRARY

Prophet is a quite fresh and promising open-source library for machine learning, developed by Facebook, that gains some significant interest. It could be used for predicting time series taking into account holidays and seasonality effects. Its possible applications and deficit of scientific works concerning its usage within decision processes convinced the authors to state the research question, if the Prophet library could provide reliable prediction to support decision-making processes at the airport. The case of Radawiec airport (located near Lublin, Poland) was chosen. Official measurement data (from the last 4 years) published by the Polish Government  Institute was used to train the neural network and predict daily averages of wind speed, temperature, pressure, relative humidity and rainfall totals during the day and night. It was revealed that most of the predicted data points were within the acceptance threshold, and computations were fast and highly automated. However, the authors believe that the Prophet library is not particularly useful for airport decision-making processes because the way it handles additional regressors and susceptibility to unexpected phenomena negatively affects the reliability of prediction results

Investigation of crystalline lens overshooting: ex vivo experiment and optomechanical simulation results

Introduction: Crystalline lens overshooting refers to a situation in which the lens momentarily shifts too much from its typical location immediately after stopping the rotational movement of the eye globe. This movement can be observed using an optical technique called Purkinje imaging.Methods: In this work, an experimental setup was designed to reproduce this effect ex vivo using a fresh porcine eye. The sample was rotated 90° around its centroid using a high-velocity rotation stage, and the Purkinje image sequences were recorded, allowing us to quantify the overshooting effect. The numerical part of the study consisted of developing a computational model of the eye, based on the finite element method, that allowed us to understand the biomechanical behavior of the different tissues in this dynamic scenario. A 2D fluid–structure interaction model of the porcine eye globe, considering both the solid parts and humors, was created to reproduce the experimental outcomes.Results: Outputs of the simulation were analyzed using an optical simulation software package to assess whether the mechanical model behaves optically like the real ex vivo eye. The simulation predicted the experimental results by carefully adjusting the mechanical properties of the zonular fibers and the damping factor.Conclusion: This study effectively demonstrates the importance of characterizing the dynamic mechanical properties of the eye tissues to properly comprehend and predict the overshooting effect

How a dynamic optical system maintains image quality: Self-adjustment of the human eye

The eyeball is continually subjected to forces that cause alterations to its shape and dimensions, as well as to its optical components. Forces that induce accommodation result in an intentional change in focus; others, such as the effect of intraocular pressure fluctuations, are more subtle. Although the mechanical properties of the eyeball and its components permit mediation of such subtle forces, the concomitant optical changes are not detected by the visual system. Optical self-adjustment is postulated as the mechanism that maintains image quality. The purpose of this study was to investigate how self-adjustment occurs by using an optical model of the eyeball and to test the requisite optical and biometric conditions

Exploring swift-heavy ion irradiation of InGaN/GaN multiple quantum wells for green-emitters: the use of Raman and photoluminescence to assess the irradiation effects on the optical and structural properties

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Animal versus human research reporting guidelines impacts: literature analysis reveals citation count bias

The present study evaluated for the first time citation-impacts of human research reporting guidelines in comparison to their animal version counterparts. Re-examined and extended also were previous findings indicating that a research reporting guideline would be cited more for its versions published in journals with higher Impact Factors, compared to its duplicate versions published in journals with lower Impact Factors. The two top-ranked reporting guidelines listed in the Equator Network website (http://www.equator-network.org/) were CONSORT 2010, for parallel-group randomized trials; and STROBE, for observational studies. These two guidelines had animal study versions, REFLECT and STROBE-Vet, respectively. Together with ARRIVE, these five guidelines were subsequently searched in the Web of Science Core Collection online database to record their journal metrics and citation data. Results found that association between citation rates and journal Impact Factors existed for CONSORT guideline set for human studies, but not for STROBE or their counterparts set for animal studies. If Impact Factor was expressed in terms of journal rank percentile, no association was found except for CONSORT. Guidelines for human studies were much more cited than animal research guidelines, with the CONSORT 2010 and STROBE guidelines being cited 27.1 and 241.0 times more frequently than their animal version counterparts, respectively. In conclusion, while the journal Impact Factor is of importance, other important publishing features also strongly affect scientific manuscript visibility, represented by citation rate. More effort should be invested to improve the visibility of animal research guidelines.info:eu-repo/semantics/publishedVersio

Apple polyphenols in human and animal health*

Apples contain substantial amounts of polyphenols, and diverse phenolics mainly flavonoids and phenolic acids, have been identified in their flesh and skins. This work aimed to analyze the overall landscape of the research literature published to date on apple phenolic compounds in the context of human and animal health. The Web of Science Core Collection electronic database was queried with (apple* polyphenol*) AND (health* OR illness* OR disease* OR medic* OR pharma*) to identify relevant papers covering these words and their derivatives in the titles, abstracts, and keywords. The resulted 890 papers were bibliometrically analyzed. The VOSviewer software was utilized to produce term maps that illustrate how the frequent phrases fared in terms of publication and citation data. The apple polyphenol papers received global contributions, particularly from China, Italy, the United States, Spain, and Germany. Examples of frequently mentioned chemicals/chemical classes are quercetin, anthocyanin, catechin, epicatechin, and flavonol, while examples of frequently mentioned medical conditions are cardiovascular disease, atherosclerosis, diabetes, Alzheimers disease, and obesity. The potential health benefits of apple polyphenols on humans and animals are diverse and warrant further study.Authors acknowledge the support from The National Centre for Research and Development (NCBR) of Poland (project number POIR.01.01.01-00-0593/18).info:eu-repo/semantics/publishedVersio