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41.
The objective of the present work is to predict the formation of chevron crack in copper wire drawing process. The first part of this paper is to determine the chevron crack formation initiated by a central burst inside the wire material using experimental tests. These results are compared with results from a series of numerical simulations using the Cockcroft?CLatham fracture criterion. The second part of this work concerns the determination of a curve that divides the chevron and safe zones for a better wire drawing process. The conditions of central burst defects formation along the wire axis depend on drawing parameters and friction coefficient between the die and the wire. The friction coefficient is defined as a linear function of temperature rise which is measured close to the wire-die interface. The obtained results show that the friction coefficient depending on temperature rise during wire drawing has an impact on the damage of copper wire. 相似文献
42.
Chlor-alkali electrolysis with oxygen depolarized cathodes: history,present status and future prospects 总被引:1,自引:0,他引:1
Imad Moussallem Jakob Jörissen Ulrich Kunz Stefan Pinnow Thomas Turek 《Journal of Applied Electrochemistry》2008,38(9):1177-1194
The historical development, current status and future prospects of chlor-alkali electrolysis with oxygen depolarized cathodes
(ODCs) are summarized. Over the last decades, membrane chlor-alkali technology has been optimized to such an extent that no
substantial reduction of the energy demand can be expected from further process modifications. However, replacement of the
hydrogen evolving cathodes in the classical membrane cells by ODCs allows for reduction of the cell voltage and correspondingly
the energy consumption of up to 30%. This replacement requires the development of appropriate cathode materials and novel
electrolysis cell designs. Due to their superior long-term stability, ODCs based on silver catalysts are very promising for
oxygen reduction in concentrated NaOH solutions. Finite-gap falling film cells appear to be the technically most mature design
among the several ODC electrolysis cells that have been investigated.
相似文献
Thomas TurekEmail: |
43.
R. Ghfiri A. Amrouche A. Imad & G. Mesmacque 《Fatigue & Fracture of Engineering Materials & Structures》2000,23(11):911-916
In this paper, the hole drilling (HD) and the cold expansion (CE) processes, which were used as a technique for crack repair, were investigated in order to estimate the beneficial effects on fatigue crack initiation (FCI). The FCI life is defined as the number of cycles to initiate a new crack of 0.2 mm on the surface of the specimen. Three hole radii and three degrees of cold expansion (DCE%) values were tested after a crack propagation period. Crack retardation after the CE process was observed. This phenomenon is due to two mechanisms: retardation owing to both geometric and mechanical effects, which is produced by the stress concentration at the drilled hole, and the large strain‐induced compressive residual stresses around the hole. In this report, the influence of the loading conditions was studied. For high values of the stress intensity factor range ΔKρ around the hole (based on the pseudo crack length a + ρ), the number of cycles corresponding to crack initiation Ni is low. At the edge of the hole, the maximum stress range can be approximated by the following formula: Δσmax = 2ΔKρ /√πρ , where ρ is the hole radius and ΔKρ is the related stress intensity factor range.The FCI life extension, defined by the number of cycles corresponding to crack re‐initiation Ni , is related to the relative maximum stress range ratio Rσ = [(Δσmax )/(Δσmax )th ] where (Δσmax )th is the value of the threshold maximum stress range obtained when Ni = 2 × 106 cycles. The relationship between Ni and Rσ may be written as a power function. 相似文献
44.
45.
Raphaël T. Leriche Alexandra Palacio-Morales Marco Campetella Cesare Tresca Shunsuke Sasaki Christophe Brun François Debontridder Pascal David Imad Arfaoui Ondrej Šofranko Tomas Samuely Geoffroy Kremer Claude Monney Thomas Jaouen Laurent Cario Matteo Calandra Tristan Cren 《Advanced functional materials》2021,31(6):2007706
Transition metal dichalcogenides (TMDs) display a rich variety of instabilities such as spin and charge orders, Ising superconductivity, and topological properties. Their physical properties can be controlled by doping in electric double-layer field-effect transistors (FET). However, for the case of single layer NbSe2, FET doping is limited to ≈ 1 × 1014 cm−2, while a somewhat larger charge injection can be obtained via deposition of K atoms. Here, by performing angle-resolved photoemission spectroscopy, scanning tunneling microscopy, quasiparticle interference measurements, and first-principles calculations it is shown that a misfit compound formed by sandwiching NbSe2 and LaSe layers behaves as a NbSe2 single layer with a rigid doping of 0.55–0.6 electrons per Nb atom or ≈ 6 × 1014 cm−2. Due to this huge doping, the 3 × 3 charge density wave is replaced by a 2 × 2 order with very short coherence length. As a tremendous number of different misfit compounds can be obtained by sandwiching TMDs layers with rock salt or other layers, this work paves the way to the exploration of heavily doped 2D TMDs over an unprecedented wide range of doping. 相似文献
46.
Varadarajan Vijayakumar Neelanarayanan Venkataraman Doyle Ron Al-Shaikhli Imad Fakhri Groppe Sven 《Mobile Networks and Applications》2019,24(4):1135-1138
Mobile Networks and Applications - 相似文献
47.
Imad Khlifi Octavian Pop Jean-Christophe Dupré Pascal Doumalin Marc Huger 《Journal of the European Ceramic Society》2019,39(13):3893-3902
Industrial magnesia-spinel bricks destined for thermal shock applications often show more flexibility and improved crack growth resistance. Components from the spinel structure group are usually added to promote microcracking coming from thermal expansion mismatch. This leads to the development of toughening mechanisms that are very effective in improving the crack propagation resistance.Magnesia-hercynite composites were investigated in order to highlight their fracture process, with regard to their microstructure, by using Digital Image Correlation (DIC). The direct measurement of displacement fields between digital images of the reference state and the deformed one has provided valuable information on material deformation during loading. The aim of this work was to investigate the fracture behaviour of refractories through the coupling of the Wedge Splitting Test (WST) and DIC. By using a refined DIC process transformation taking into account a discontinuity of displacement, called 2P-DIC, a more effective characterisation of the fracture behaviour was achieved. 相似文献
48.
Imad M. Alatiqi 《加拿大化工杂志》1990,68(4):680-684
New measures for robustness are proposed for linear multivariable control systems. A new theorem is presented to account for the controllability of systems that contain an integrating element, in the presence of additive uncertainties. The theorem leads to the definition of a sufficient condition for robust integral controllability: robustness margin (RM). The ratio of robustness margins for competing control or processs structures can be used to discriminate between these structures. These measures are useful, especially in design stages, since their calculation depends only on steady state information. Applications to several published distillation systems show the merits of these robustness measures. 相似文献
49.
50.
Ternary palladates CdPd3O4 and TlPd3O4 have been studied theoretically using the generalized gradient approximation (GGA), modified Becke–Johnson, and spin–orbit coupling (GGA–SOC) exchange–correlation functionals in the density functional theory (DFT) framework. From the calculated ground-state properties, it is found that SOC effects are dominant in these palladates. Mechanical properties reveal that both compounds are ductile in nature. The electronic band structures show that CdPd3O4 is metallic, whereas TlPd3O4 is an indirect-bandgap semiconductor with energy gap of 1.1 eV. The optical properties show that TlPd3O4 is a good dielectric material. The dense electronic states, narrow-gap semiconductor nature, and Seebeck coefficient of TlPd3O4 suggest that it could be used as a good thermoelectric material. The magnetic susceptibility calculated by post-DFT treatment confirmed the paramagnetic behavior of these compounds. 相似文献