Effect of tooth shape to size of contact stress noninvolute gearing

The article describes the effect of the tooth shape to the size of the contact stress. Using the geometrical parameters konex-concave gearing can change the tooth profile, which can be achieved by reducing the size of the contact stress. Important role played by reduced radii of curvature, which significantly affect to the size of these stress. Comparative two places around the beginning (point B) and end (point D) on the line of action.В статье описывается влияние формы зуба с размером контактного напряжения. В геометрических параметрах выпукло-вогнутой передачи можно изменить форму зубов, которая может быть достигнута за счет сокращения размеров контактных напряжений. Важную роль играет сокращение радиусов кривизны, которая существенно влияет на размер этих напряжений. Приравнивается два места вокруг самого начала (точка B) и конца (точка D) на линии зацепления, которые находится в непосредственной близости от этих точек представленых одно и двухпарным зацеплением

Studija promjena ispod obrađene površine i pridruženi fenomeni u zoni rezanja tijekom bušenja nehrđajućeg čelika s niskim sadržajem ugljika

This article presents the results of experiments that concerned the verification of machined surface conditions of workpieces from a new austenitic stainless steel with Extra Low Carbon (ELC) Cr22Ni9MoTi compared with stainless steels Cr18Ni8. The results of cutting zone evaluation under cutting speed 80 m/min, depth of cut 2,75 mm and feed 0,08 mm per rev., a definition of shear level angle Φ1. For Cr22Ni9MoTi steel Φ1 is 36° to 39°. The acquired results are interesting in that for the defined conditions we can achieve a quality outer surface after cutting with roughness parameters down to around 0,65 μm at cutting speed 80 m/min and feed 0.08 mm per rev.Rad prikazuje rezultate eksperimentalnog istraživanja koji se odnose na verifikaciju uvjeta strojne obrade radnih komada od austenitnog nehrđajućeg čelika sa posebno niskim sadržajem ugljika (ELC) Cr22Ni9MoTi u usporedbi sa nehrđajućim čelikom Cr18Ni8. Rezultati ocjene rezne površine kod brzine rezanja 80 m/min, dubine reza 2,75 mm i posmaka 0,08 mm po okretaju definiraju vrijednost smičnog kuta Φ1. Za čelik Cr22Ni9MoTi Φ1 je 36° do 39°. Prikupljeni rezultati su zanimljivi za definiranje uvjeta pod kojim se može postići kvaliteta hrapavosti vanjske površine nakon rezanja do oko 0,65 μm kod brzine rezanja 80 m/min i posmaka 0,08 mm po okretaju

The shortcomings of semi-local and hybrid functionals: what we can learn from surface science studies

A study of the adsorption of CO on late 4d and $5d$ transition metal (111) surfaces (Ru, Rh, Pd, Ag, Os, Ir, and Pt) considering atop and hollow site adsorption is presented. The applied functionals include the gradient corrected PBE and BLYP functional, and the corresponding hybrid Hartree-Fock density functionals HSE and B3LYP. We find that PBE based hybrid functionals (specifically HSE) yield, with the exception of Pt, the correct site order on all considered metals, but they also considerably overestimate the adsorption energies compared to experiment. On the other hand, the semi-local BLYP functional and the corresponding hybrid functional B3LYP yield very satisfactory adsorption energies and the correct adsorption site for all surfaces. We are thus faced with a Procrustean problem: the B3LYP and BLYP functionals seem to be the overall best choice for describing adsorption on metal surfaces, but they simultaneously fail to account well for the properties of the metal, vastly overestimating the equilibrium volume and underestimating the atomization energies. Setting out from these observations, general conclusions are drawn on the relative merits and drawbacks of various semi-local and hybrid functionals. The discussion includes a revised version of the PBE functional specifically optimized for bulk properties and surface energies (PBEsol), a revised version of the PBE functional specifically optimized to predict accurate adsorption energies (rPBE), as well as the aforementioned BLYP functional. We conclude that no semi-local functional is capable to describe all aspects properly, and including non-local exchange also only improves some, but worsens other properties.Comment: 12 pages, 6 figures; to be published in New Journal of Physic

You took the words right out of my mouth:Dual-fMRI reveals intra- and inter-personal neural processes supporting verbal interaction.

Verbal communication relies heavily upon mutual understanding, or common ground. Inferring the intentional states of our interaction partners is crucial in achieving this, and social neuroscience has begun elucidating the intra- and inter-personal neural processes supporting such inferences. Typically, however, neuroscientific paradigms lack the reciprocal to-and-fro characteristic of social communication, offering little insight into the way these processes operate online during real-world interaction. In the present study, we overcame this by developing a “hyperscanning” paradigm in which pairs of interactants could communicate verbally with one another in a joint-action task whilst both undergoing functional magnetic resonance imaging simultaneously. Successful performance on this task required both interlocutors to predict their partner's upcoming utterance in order to converge on the same word as each other over recursive exchanges, based only on one another's prior verbal expressions. By applying various levels of analysis to behavioural and neuroimaging data acquired from 20 dyads, three principal findings emerged: First, interlocutors converged frequently within the same semantic space, suggesting that mutual understanding had been established. Second, assessing the brain responses of each interlocutor as they planned their upcoming utterances on the basis of their co-player's previous word revealed the engagement of the temporo-parietal junctional (TPJ), precuneus and dorso-lateral pre-frontal cortex. Moreover, responses in the precuneus were modulated positively by the degree of semantic convergence achieved on each round. Second, effective connectivity among these regions indicates the crucial role of the right TPJ in this process, consistent with the Nexus model. Third, neural signals within certain nodes of this network became aligned between interacting interlocutors. We suggest this reflects an interpersonal neural process through which interactants infer and align to one another's intentional states whilst they establish a common ground

Ab-initio density functional study of O on the Ag(001) surface

The adsorption of oxygen on the Ag(001) is investigated by means of density functional techniques. Starting from a characterization of the clean silver surfaces oxygen adsorption in several modifications (molecularly, on-surface, sub-surface, Ag$_2$O) for varying coverage was studied. Besides structural parameters and adsorption energies also work-function changes, vibrational frequencies and core level energies were calculated for a better characterization of the adsorption structures and an easier comparison to the rich experimental data.Comment: 26 pages, 8 figures, Surf. Sci. accepte

CO adsorption on neutral iridium clusters

The adsorption of carbon monoxide on neutral iridium clusters in the size range of n = 3 to 21 atoms is investigated with infrared multiple photon dissociation spectroscopy. For each cluster size only a single v(CO) band is present with frequencies in the range between 1962 cm-1 (n = 8) and 1985 cm-1 (n = 18) which can be attributed to an atop binding geometry. This behaviour is compared to the CO binding geometries on clusters of other group 9 and 10 transition metals as well as to that on extended surfaces. The preference of Ir for atop binding is rationalized by relativistic effects on the electronic structure of the later 5d metals

Use of Spectroscopic Techniques to Monitor Changes in Food Quality during Application of Natural Preservatives: A Review

Consumer demand for food of high quality has driven research for alternative methods of food preservation on the one hand, and the development of new and rapid quality assessment techniques on the other hand. Recently, there has been a growing need and interest in healthier food products, which has led to an increased interest in natural preservatives, such as essential oils, plant extracts, and edible films and coatings. Several studies have shown the potential of using biopreservation, natural antimicrobials, and antioxidant agents in place of other processing and preservation techniques (e.g., thermal and non-thermal treatments, freezing, or synthetic chemicals). Changes in food quality induced by the application of natural preservatives have been commonly evaluated using a range of traditional methods, including microbiology, sensory, and physicochemical measurements. Several spectroscopic techniques have been proposed as promising alternatives to the traditional time- consuming and destructive methods. This review will provide an overview of recent studies and highlight the potential of spectroscopic techniques to evaluate quality changes in food products following the application of natural preservatives

Development of Near Infrared Spectroscopy Models for Quantitative Prediction of the Content of Bioactive Compounds in Olive Leaves

The objective of this work was to evaluate the ability of artificial neural networks (ANN) in near infrared (NIR) spectra calibration models to predict the total polyphenolic content, antioxidant activity, and extraction yield of the olive leaves aqueous extracts prepared with three extraction procedures (conventional extraction, microwave-assisted extraction, and microwave-ultrasound-assisted extraction). Partial least squares (PLS) models were developed from principal component analyses (PCA) scores of NIR spectra of olive leaf aqueous extracts in terms of total polyphenols concentration, antioxidant activity, and extraction yield for each extraction procedure. PLS models were used to view which PCA scores are the best suited as input for ANN based on three output variables. ANN showed very good correlation of NIRs and all tested variables, especially in the case of total polyphenolic content (TPC). Therefore, ANN can be used for the prediction of total polyphenol concentrations, antioxidant activity, and extraction yield of plant extracts based on the NIR spectra

Identification and design principles of low hole effective mass p-type transparent conducting oxides

The development of high-performance transparent conducting oxides is critical to many technologies from transparent electronics to solar cells. Whereas n-type transparent conducting oxides are present in many devices, their p-type counterparts are not largely commercialized, as they exhibit much lower carrier mobilities due to the large hole effective masses of most oxides. Here we conduct a high-throughput computational search on thousands of binary and ternary oxides and identify several highly promising compounds displaying exceptionally low hole effective masses (up to an order of magnitude lower than state-of-the-art p-type transparent conducting oxides), as well as wide band gaps. In addition to the discovery of specific compounds, the chemical rationalization of our findings opens new directions, beyond current Cu-based chemistries, for the design and development of future p-type transparent conducting oxides.United States. Office of Naval Research (Award N00014-11-1-0212

A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor

Selective, robust and cost-effective chemical sensors for detecting small volatile-organic compounds (VOCs) have widespread applications in industry, healthcare and environmental monitoring. Here we design a Pt(II) pincer-type material with selective absorptive and emissive responses to methanol and water. The yellow anhydrous form converts reversibly on a subsecond timescale to a red hydrate in the presence of parts-per-thousand levels of atmospheric water vapour. Exposure to methanol induces a similarly-rapid and reversible colour change to a blue methanol solvate. Stable smart coatings on glass demonstrate robust switching over 104 cycles, and flexible microporous polymer membranes incorporating microcrystals of the complex show identical vapochromic behaviour. The rapid vapochromic response can be rationalised from the crystal structure, and in combination with quantum-chemical modelling, we provide a complete microscopic picture of the switching mechanism. We discuss how this multiscale design approach can be used to obtain new compounds with tailored VOC selectivity and spectral responses