Search results for "Mechanical engineering"
showing 10 items of 4245 documents
The influence of the cycloid disc bearing type on the cycloidal speed reducer efficiency
2021
The robotics industry has experienced a rapid expansion in the last decade. As a result, the market of speed reducers with high gear ratios, high precision and a compact design is growing rapidly. In addition to these characteristics, it is very important for gear trains to have high efficiency. Because of their compact design, cycloidal speed reducers are not exposed to axial forces, which is their important characteristic. This means that radial bearings can be used in their supports. The bearing type has significant effects not only on the design and dimensions of the cycloid speed reducer but also on its efficiency. In this paper, an analysis of power losses for different types of rolli…
Acene-type donors bearing one 1,3-dithiole ring
1999
Abstract A series of acene-type donors bearing only one 1,3-dithiole ring have been synthesized by following a Wittig-Horner reaction from 7 H -benz[ d,e ]anthracen-7-one and several phosphonate esters. The excellent donor properties have been studied using both experimental techniques and quantum-chemical calculations and reveal that the extraction of the first electron in the oxidation process occurs from the dithiole ring (0.42 e) and the acene unit (0.58 e).
Experimental Observations of Flow and Bed Processes in Large-Amplitude Meandering Flume
2009
Meanders of large amplitude often exhibit asymmetric planform shape or subsidiary bends. The present work is aimed at improving on understanding of the morphodynamic phenomena affecting the bed evolution of large amplitude meandering channels. Attention is focused on the development of the steady point bar-pool configuration and of the superimposed large-scale migrating bed forms; of particular interest is the role of the changing channel curvature and bed topography variation on flow pattern. A series of experiments was carried out in a sine-generated large-amplitude meandering flume, for two values of width-to-depth ratio. Maps documenting the bed topography and the flow pattern along the…
Experimental observations of upstream overdeepening
2005
The issue of morphodynamic influence in meandering streams is investigated through a series of laboratory experiments on curved and straight flumes. Both qualitative and quantitative observations confirm the suitability of the recent theoretical developments (Zolezzi & Seminara 2001) that indicate the occurrence of two distinct regimes of morphodynamic influence, depending on the value of the width ratio of the channel β. The threshold value βR separating the upstream from the downstream influence regimes coincides with the resonant value discovered by Blondeaux & Seminara (1985). Indeed it is observed that upstream influence may occur only in relatively wide channels, while narrower stream…
Predicting mobile apps spread: An epidemiological random network modeling approach
2017
[EN] The mobile applications business is a really big market, growing constantly. In app marketing, a key issue is to predict future app installations. The influence of the peers seems to be very relevant when downloading apps. Therefore, the study of the evolution of mobile apps spread may be approached using a proper network model that considers the influence of peers. Influence of peers and other social contagions have been successfully described using models of epidemiological type. Hence, in this paper we propose an epidemiological random network model with realistic parameters to predict the evolution of downloads of apps. With this model, we are able to predict the behavior of an app…
Surface finish on hardened bearing steel parts produced by superhard and abrasive tools
2007
New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding …
Evaluation of the bending behaviour of laminated glass beams via electronic speckle pattern interferometry
2017
The paper is devoted to the experimental analysis of the kinematical and mechanical behaviour of laminated glass beam structures. In particular, the utilized laminated glass specimens are composed of two glass layers bonded by a polymer layer constituted by Ethylene-vinyl acetate whose thickness has been nominally considered as constant for all the specimens. The experimental behaviour of the analyzed specimens is deduced by applying Electronic Speckle- Pattern Interferometry technique; actually, among optical methods this technique (handled by phase-stepping technique) is very effective to obtain a full-field displacement map and to numerically achieve the longitudinal strain. In particula…
A bending theory of thermoelastic diffusion plates based on Green-Naghdi theory
2017
Abstract This article is concerned with bending plate theory for thermoelastic diffusion materials under Green-Naghdi theory. First, we present the basic equations which characterize the bending of thin thermoelastic diffusion plates for type II and III models. The theory allows for the effect of transverse shear deformation without any shear correction factor, and permits the propagation of waves at a finite speed without energy dissipation for type II model and with energy dissipation for type III model. By the semigroup theory of linear operators, we prove the well-posedness of the both models and the asymptotic behavior of the solutions of type III model. For unbounded plate of type III…
Inhibitoren der Korrosion 30 (1,2) - Vergleichende Studien über das Verhalten bekannter und bisher unbekannter Inhibitoren der Korrosion des Kupfers …
1985
Folgende Verbindungen wurden auf ihre Fahigkeit zur Inhibierung der Korrosion von Kupferproben unter Standardbedingungen uberpruft: Benzotriazol (BTA), 5-Aminotetrazol-monohydrat (5-AT), 2,5-Diphenyl-3-(m-chlorphenyl)-tetrazolium-nitrat (Tetrazin-B), α- und β-Naphthylamin, Phenylthioharnstoff, Xanthanwasserstoff, 2-Mercaptothiazolin (2-MT) und Kupferron. Folgende Messungen wurden durchgefuhrt: Bestimmung der Geschwindigkeit der Sauerstoffaufnahme im Schuttelversuch und pH-statische Verfolgung des Korrosionsverlaufs in Abhangigkeit (a) von der Konzentration des Inhibitors, (b) dem Verteilungszustand der Kupferprobe (Korn, Staub, Blech), (c) der Anwesenheit von Cu2+-Ionen und (d) dem pH-Wert.…
Application of the 3-D boundary element method to delaminated composite structures
2013
A three-dimensional boundary element model for anisotropic solids is presented to study the fracture mechanics behavior of delaminated composite structures. The multi-domain technique is implemented to model the layered configurations and the cracks occurring at bi-material interface. The Modified Crack Closure Integral technique is implemented to characterize the fracture mechanics behavior of delaminations in terms of the total energy release rate and mode mix phase angles. Validating analyses, performed on different delaminated configurations, have shown the effectiveness of the proposed approach. Moreover, some original results are presented to investigate the effects of the stacking se…