Steel Case Hardening Using Deformational cutting

This article describes some fundamental principles, specific features and the technological capabilities of a new method of quenching steel surface by turning without separation of chips. The underlying process of this method is a deformational cutting which is based on the undercutting and deformation of surface layers that remain attached to the workpiece. The energy released in the area of deformational cutting is used to heat the undercut layer up to the temperatures of structural and phase transformation of workpiece material. This type of process results into a hardened structure formed at the surface which consists of inclined thin undercut layers tightly packed and stuck (glued) together and form a single solid body. The resulting hardened structures achieved in steels workpieces are presented in the article. The samples hardened by deformational cutting showed a higher wear resistance compared to samples with traditional quenching. This paper also describes an estimation of the thermo-physical parameters of the deformational cutting process

Posterior distributions for likelihood ratios in forensic science

Evaluation of evidence in forensic science is discussed using posterior distributions for likelihood ratios. Instead of eliminating the uncertainty by integrating (Bayes factor) or by conditioning on parameter values, uncertainty in the likelihood ratio is retained by parameter uncertainty derived from posterior distributions. A posterior distribution for a likelihood ratio can be summarised by the median and credible intervals. Using the posterior mean of the distribution is not recommended. An analysis of forensic data for body height estimation is undertaken. The posterior likelihood approach has been criticised both theoretically and with respect to applicability. This paper addresses the latter and illustrates an interesting application area

Delamination and longitudinal cracking in multi-layered composite nanostructured coatings and their influence on cutting tool life

This paper presents the results of a study of the mechanisms of delamination and the formation of longitudinal cracks in the structure of multi-layered nano-structured coatings to predict the mechanisms for further improvement of tool life and the reliability of metal-cutting tools. Various mechanisms of formation of longitudinal cracks and delaminations in coatings on rake and flank tool surfaces, which vary based on the compositions and architectures of the coatings, are addressed. In addition, the influence of internal defects, including embedded microdrops and pores, on the formation of cracks and delaminations and the failure of coatings is discussed. The importance of ensuring a balance of the basic properties of coatings to achieve high wear resistance and maximum tool life of coated metal cutting tools is shown. The properties of coatings and the natures of their failures, as investigated during scratch testing and dry turning of steel C45, are provided

Nanostructured Multilayer Composite Coatings on Ceramic Cutting Tools for Finishing Treatment of High-Hardness Quenched Steels

The functional role of nanostructured multilayer composite coatings (NMCC) deposited on the operating surfaces of replaceable faceted cutting inserts (CI) from cutting ceramics based on aluminum oxides with additives of titanium carbides is studied. It is shown that the developed NMCC not only raise substantially the endurance of the ceramic tools under high-speed dry treatment of quenched steels but also improve the quality and accuracy of processing of the parts and the ecological parameters of the cutting process

Development and research of nanostructured multilayer composite coatings for tungsten-free carbides with extended area of technological applications

This paper discusses aspects of the development of nanostructured multilayer composite coatings (NMCCs) formed using the processes of filtered cathodic vacuum arc deposition (FCVAD) for application to the tungsten-free carbides (cermets) based on TiC-(Ni,Mo) and TiCN-(Ni,Mo) compounds in order to improve cutting properties of tools and to expand the area of their technological application. NMCCs were used not only to improve the physical and mechanical properties of the working surfaces of tools but also to ensure the control over contact processes during cutting. The study has shown that despite their high hardness, thermal stability and resistance to scaling, low tendency to diffusion with the material being machined, and tungsten-free carbides are characterized by relatively low fracture toughness and bending strength, low thermal conductivity. With regard to the above properties, tungsten-free carbides are inferior not only to tungsten WC-Co carbides but also to WC-TiC-Co carbides with binder content of less than 8 % (by weight). Therefore, cutting tools made of tungsten-free carbides have a limited range of technological application in interrupted cutting, machining of hard-to-cut alloys and steels. With respect to this, the paper considers the possibility of directional control over contact processes during cutting with the use of NMCCs to create more balanced properties of tungsten-free carbides with regard to hardness and toughness. This work has developed architecture of three-component nanostructured multilayer composite coatings, the methods for selecting functions and rational component parameters of architecture for tools made of tungsten-free carbides. The developed compositions of NMCCs have improved cutting properties of tungsten-free carbides and expanded the area of their technological application in cutting of heat-treated steels of increased hardness and machining of heat-resistant alloys. © 2016 Springer-Verlag Londo

A study of the cutting properties and wear mechanism of ceramic edge tools with nanostructure multilayer composite coatings

The paper presents the results of studies of the cutting properties and wear mechanism of the edge cutting tool equipped with replaceable indexable inserts made of cutting ceramic with nanoscale multilayer composite coatings when cutting hardened steel. It has been shown that applying the latter allows one to tune the contact processes based on the changes in friction and lengths of dense and complete contacts between the chip and the rake face of the cutting tools, thereby reducing normal contact strains and the probability of macro- and microbrittle fracture in the contact areas of the tool

Power gain exhibited by motile mechanosensory neurons in Drosophila ears

In insects and vertebrates alike, hearing is assisted by the motility of mechanosensory cells. Much like pushing a swing augments its swing, this cellular motility is thought to actively augment vibrations inside the ear, thus amplifying the ear's mechanical input. Power gain is the hallmark of such active amplification, yet whether and how much energy motile mechanosensory cells contribute within intact auditory systems has remained uncertain. Here, we assess the mechanical energy provided by motile mechanosensory neurons in the antennal hearing organs of Drosophila melanogaster by analyzing the fluctuations of the sound receiver to which these neurons connect. By using dead WT flies and live mutants (tilB(2), btv(5P1), and nompA(2)) with defective neurons as a background, we show that the intact, motile neurons do exhibit power gain. In WT flies, the neurons lift the receiver's mean total energy by 19 zJ, which corresponds to 4.6 times the energy of the receiver's Brownian motion. Larger energy contributions (200 zJ) associate with self-sustained oscillations, suggesting that the neurons adjust their energy expenditure to optimize the receiver's sensitivity to sound. We conclude that motile mechanosensory cells provide active amplification; in Drosophila, mechanical energy contributed by these cells boosts the vibrations that enter the ear

The impact of ischemic stroke on atrial fibrillation-related healthcare cost: a systematic review

Aim: To summarize healthcare costs incurred by patients with atrial fibrillation (AF) who developed ischemic stroke, explore factors associated with increased cost and highlight the importance of anticoagulation therapy for stroke prophylaxis. / Methods: A systematic literature search of PubMed, EMBASE, Web of Science and the health economic evaluation database was conducted up to December 2015. Studies focused on the cost and/or resource utilization of ischemic stroke in patients with AF were included. Reported costs were converted to international dollars (I$) and adjusted to 2015 values. Alongside the narrative review of included studies, Spearman’s correlation, independent-samples t-test and one-way ANOVA were used to explore factors associated with cost differences between studies. / Results: Sixteen studies published from nine countries were identified. Based on currency conversion rates in 2015, ischemic stroke related healthcare costs were estimated to be I$41,420, I$12,895 and I$8,184 for high-income, upper middle-income and lower middle-income economies respectively. Local GDP per capita accounted for approximately 50% of the healthcare cost variation among countries. Major component of overall cost was from hospitalization. Ischemic stroke incurring in patients with AF ≥75 years were 2.3 times that of their younger peers (p=0.049). / Conclusions: The economic burden from ischemic stroke in patients with AF is considerable with positive association to country income. Clinicians and stakeholders should be aware of the importance of anticoagulation therapies in stroke prophylaxis, the occurrence of stroke and the downstream economic burden on an increasingly aging population

Strategy for visualisation of the activity of phase change materials by transient plane source technique

Through a combination of theoretical and experimental research, this paper aims at evaluating the suitability of a transient plane heat source (TPS) method for the visualisation of the activity of phase change materials (PCMs). The TPS method provides measurements of thermal conductivity and thermal diffusivity of a material in a transient course. It has previously been tested on various building materials but not on PCMs. In this study TPS was tested in a laboratory environment on two inorganic PCMs (salt-hydrates), with melting temperatures 21 oC and 24 oC respectively. Based on the experimental trials, the technique has shown to be a valuable technique for the identification of the activity of phase change material