Search results for " Wear"

Wear modelling in mild steel orthogonal cutting when using uncoated carbide tools

2007

Abstract Wear prediction in machining has been recently studied by FEM although the use of numerical methods for such applications is still a very challenging research issue. In fact, wear phenomenon involves many aspects related to process mechanics which require a very accurate modelling. In other words, only a very punctual code set-up can help the researchers in order to obtain consistent results in FE analysis. The high relative velocity between chip and tool requires effective material models as well as friction modelling at the interface. Moreover the prediction of temperature distribution is another critical task; in the paper some different procedures are discussed. Subsequently a …

Dietary behaviour and competition for vegetal resources in two Early Miocene pecoran ruminants from Central Spain

2012

ABSTRACT Dietary behaviour and competition for resources are investigated for the small-sized ruminants Andegameryx Ginsburg, 1971 and Procervulus Gaudry, 1877 representatives of two largely distinct states of diversification of pecorans. Results obtained from dental microwear and mesowear methodologies are concordant with a mixed feeder strategy for the taxa from the Early Miocene environments of the Iberian Chain (Central Spain). Further, the Spanish taxa investigated had less abrasive diets than their relatives from others similarly aged localities in Europe. This fact raises an important evolutionary uncertainty concerning the traditional characterization of first pecorans as specialize…

Tool Wear and Damage

2008

This chapter provides comprehensive knowledge regarding tool wear mechanisms and characterizes their physical fundamentals. Adhesion, abrasion, diffusion and oxidation are selected as predominant mechanisms controlling tool wear, depending on the mechanical and thermal conditions at the rake and flank faces. The analytical models describing the wear rate and volumetric material loss for different wear mechanisms are provided. The tool wear indicators related to crater, flank and notch wear specified in ISO 3685 are presented for both flat-faced and grooved tools. Tool life is defined and corresponding models, including the influence of cutting speed, feed and the depth of cut, are derived. …

A study on the effect of contact pressure during physical activity on photoplethysmographic heart rate measurements

2020

Heart rate (HR) as an important physiological indicator could properly describe global subject&rsquo

Post-mortem enamel surface texture alteration during taphonomic processes—do experimental approaches reflect natural phenomena?

2022

Experimental approaches are often used to better understand the mechanisms behindand consequences of post-mortem alteration on proxies for diet reconstruction.Dental microwear texture analysis (DMTA) is such a dietary proxy, using dental wearfeatures in extant and extinct taxa to reconstruct feeding behaviour and mechanicalfood properties. In fossil specimens especially, DMTA can be biased by post-mortemalteration caused by mechanical or chemical alteration of the enamel surface. Herewe performed three different dental surface alteration experiments to assess the effectof common taphonomic processes by simplifying them: (1) tumbling in sedimentsuspension to simulate fluvial transport, (2) s…

Hot Impression Die Forging Process: An Approach to Flash Design for Tool Life Improvement

2005

In impression die forging the role of the flash geometry is fundamental since a proper design of the flash land strongly influences both the complete die filling and the die wear (i.e. the die life and the related costs). In this paper an integrated approach between numerical simulations and statistical tools was developed with the aim to optimize flash thickness in order to reduce die wear and to minimize material wasting. As wear is regarded, an analytical model depending on sliding velocity, temperature, die hardness and contact pressure was utilized during the numerical simulations of the process in order to reach a wear evaluation for different values of the flash design variables. Thu…

Information Dynamics of the Brain, Cardiovascular and Respiratory Network during Different Levels of Mental Stress

2019

In this study, an analysis of brain, cardiovascular and respiratory dynamics was conducted combining information-theoretic measures with the Network Physiology paradigm during different levels of mental stress. Starting from low invasive recordings of electroencephalographic, electrocardiographic, respiratory, and blood volume pulse signals, the dynamical activity of seven physiological systems was probed with one-second time resolution measuring the time series of the &delta

STUDIO E VALIDAZIONE DI SISTEMI PER L’IDENTIFICAZIONE E IL MONITORAGGIO DI PARAMETRI BIOMEDICI ATTI ALLA PREVENZIONE DI EVENTI INDESIDERATI E ALL’ASS…

L’aumento delle patologie cronico-degenerative nella popolazione mondiale ha comportato un numero sempre maggiore di individui richiedenti assistenza sanitaria, generando, nell’ambito delle realtà ospedaliere, diverse problematiche relative al miglioramento della qualità di vita dei pazienti, ai costi e alla gestione di un numero sempre crescente di soggetti ammalati. Il trattamento sanitario e la ricerca di base si sono pertanto orientati verso la prevenzione delle condizioni che predispongono i soggetti ai peggioramenti clinici e ai ricoveri ospedalieri, puntando sia su nuovi sistemi indossabili di monitoraggio per individuare precocemente i segni di peggioramento, sia su sistemi che poss…

Impact of contact lens material and design on the ocular surface.

2018

BACKGROUND: To evaluate the impact on the ocular surface of a daily disposable hydrogel contact lens with high water content compared with two silicone hydrogel daily disposable lenses of lower water content. METHODS: The hydrogel lens assessed was made from nesofilcon A and the silicone hydrogel lenses were made of delefilcon A and stenfilcon A. Contact lens thickness was measured to assess material stability during daily wear, and ocular surface parameters such as tear film osmolarity, tear meniscus area and central corneal thickness were also assessed. Optical quality was analysed for all cases by means of wavefront aberrometry. RESULTS: The nesofilcon A was shown to be the thinnest lens…

The process by which perceived autonomy support predicts motivation, intention, and behavior for seasonal influenza prevention in Hong Kong older adu…

2017

Background: This study examined the effectiveness of a theoretical framework that integrates self-determination theory (SDT) and the theory of planned behavior (TPB) in explaining the use of facemasks to prevent seasonal influenza among Hong Kong older adults. Methods: Data were collected at two time points in the winter in Hong Kong, during which influenza is most prevalent. At Time 1, older adults (N = 141) completed self-report measures of SDT (perceived autonomy support from senior center staff, autonomous motivation for influenza prevention) and TPB (attitude, subjective norm, perceived behavioral control, and intention for influenza prevention) constructs with respect to facemask used…