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51.
Constantin Claudiu Văduva Nicolae Vaszilcsin Andrea Kellenberger Mihai Medeleanu 《Journal of Applied Electrochemistry》2012,42(4):217-224
To improve the quality requirements for copper deposits, the influence of some inhibition agents added to the acidic copper
bath has been studied. Several aromatic nitrogen compounds have been tested as inhibition agents, such as aniline, N-methylaniline, N-ethylaniline, N,N-dimethylaniline (DMA), and N,N-diethylaniline (DEA). The electrochemical behavior of these organic additives and the most relevant aspects of the electrochemical
behavior of copper in acid solutions have been analyzed by cyclic voltammetry. At the same time, a correlation between voltammetric
data and molecular properties of protonated amines obtained by molecular modeling has been performed. The morphology of the
copper deposits obtained in the absence and presence of organic compounds has been studied by scanning electron microscopy.
An improvement of the roughness degree and crystallite size upon addition of aromatic amine has been found. Best results were
obtained for DMA and DEA working at room temperature (25 ± 0.1 °C) and 200 A m−2 current density, in 1 mol L−1 sulfuric acid solution with 50 g L−1 Cu2+. 相似文献
52.
Predrag Lazi? Nicolae Atodiresei Mojtaba Alaei Stefan Blügel 《Computer Physics Communications》2010,181(2):371-3755
Nowadays the state of the art Density Functional Theory (DFT) codes are based on local (LDA) or semilocal (GGA) energy functionals. Recently the theory of a truly nonlocal energy functional has been developed. It has been used mostly as a post-DFT calculation approach, i.e. by applying the functional to the charge density calculated using any standard DFT code, thus obtaining a new improved value for the total energy of the system. Nonlocal calculation is computationally quite expensive and scales as N2 where N is the number of points in which the density is defined, and a massively parallel calculation is welcome for a wider applicability of the new approach. In this article we present a code which accomplishes this goal.
Program summary
Program title: JuNoLoCatalogue identifier: AEFM_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFM_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 176 980No. of bytes in distributed program, including test data, etc.: 2 126 072Distribution format: tar.gzProgramming language: Fortran 90Computer: any architecture with a Fortran 90 compilerOperating system: Linux, AIXHas the code been vectorised or parallelized?: Yes, from 1 to 65536 processors may be used.RAM: depends strongly on the problem's size.Classification: 7.3External routines:• FFTW (http://www.tw.org/)• MPI (http://www.mcs.anl.gov/research/projects/mpich2/ or http://www.lam-mpi.org/)Nature of problem: Obtaining the value of the nonlocal vdW-DF energy based on the charge density distribution obtained from some Density Functional Theory code.Solution method: Numerical calculation of the double sum is implemented in a parallel F90 code. Calculation of this sum yields the required nonlocal vdW-DF energy.Unusual features: Binds to virtually any DFT program.Additional comments: Excellent parallelization features.Running time: Depends strongly on the size of the problem and the number of CPUs used. 相似文献53.
Infrastructure-as-a-Service (IaaS) cloud computing is gaining significant interest in industry and academia as an alternative platform for running HPC applications. Given the need to provide fault tolerance, support for suspend–resume and offline migration, an efficient Checkpoint-Restart mechanism becomes paramount in this context. We propose BlobCR, a dedicated checkpoint repository that is able to take live incremental snapshots of the whole disk attached to the virtual machine (VM) instances. BlobCR aims to minimize the performance overhead of checkpointing by persisting VM disk snapshots asynchronously in the background using a low overhead technique we call selective copy-on-write. It includes support for both application-level and process-level checkpointing, as well as support to roll back filesystem changes. Experiments at large scale demonstrate the benefits of our proposal both in synthetic settings and for a real-life HPC application. 相似文献
54.
Interactive online help systems are considered to be a fruitful supplement to traditional IT helpdesks, which are often overloaded. They often comprise user-generated FAQ collections playing the role of technology-based conceptual artifacts. Two main questions arise: how the conceptual artifacts should be used, and which factors influence their acceptance in a community of practice (CoP). Firstly, this paper offers a theoretical frame and a usage scenario for technology-based conceptual artifacts against the theoretical background of the academic help-seeking and CoP approach. Each of the two approaches is extensively covered by psychological and educational research literature, however their combination is not yet sufficiently investigated. Secondly, the paper proposes a research model explaining the acceptance of conceptual artifacts. The model includes users' expectations toward the artifact, perceived social influence and users' roles in the CoP as predictors of artifact use intention and actual usage. A correlational study conducted in an academic software users' CoP and involving structural equations modeling validates the model, suggesting thus a research line that is worth further pursuing. For educational practice, the study suggests three ways of supporting knowledge sharing in CoPs, i.e. use of technology-based conceptual artifacts, roles and division of labor, and purposeful communication in CoPs. 相似文献
55.
The paper introduces a new class of two-axis flexure hinges with axially-collocated and symmetric notches as an alternative to the existing flexure designs with serially-disposed notches. A generic formulation is developed in terms of the geometric curves defining the two notches which includes assessing the capacity of rotation, precision of rotation, sensitivity to parasitic effects, stress values, motion efficiency and shearing effects by means of compliance factors. Closed-form compliance equations are derived for a two-axis flexure hinge that is defined by two non-identical parabolic profiles. The analytical model predictions are confirmed by finite element data. A numerical comparison is made of the parabolic flexure with a constant rectangular cross-section flexure hinge in terms of several performance criteria. 相似文献
56.
Otilia Catanescu Nicolae Hurduc Dan Scutaru Aurel Stoleru Cristofor I. Simionescu 《大分子材料与工程》1999,273(1):91-95
Polyethers based on bis(2-chloroethyl) ether and various bisphenols were obtained using a phase transfer catalysis technique in a liquid/liquid system. 4,4′-Dihydroxyazobenzene, 4,4′-dihydroxybiphenyl, bisphenol A, 2,7-dihydroxynaphthalene and 4,4′-dihydroxydiphenyl) sulfide were used. Only the polymers with azobenzene and biphenyl units exhibited mesophases, since the others have semi-crystalline or amorphous structures. The polymers were characterized by 1H NMR, DSC and optical microscopy in polarized light. The molecular weights of the samples were low, situated in the oligomeric domain. The various transfer rates of the bisphenols from the aqueous to the organic phase, in some cases, led to very different copolymerization ratios as compared to the feed ratios. The LC polymers exhibited monotropic mesophases, probably for conformational reasons. A comparison between similar polyether structures containing the diethyletheric spacer and an oxetanic one was effectuated. 相似文献
57.
Denis Mihaela Panaitescu Zina Vuluga Petru V. Notingher Cristian Nicolae 《Polymer Engineering and Science》2013,53(10):2081-2092
The effect of poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) copolymer on the thermal and dielectric properties of polypropylene (PP)—nanosilica (NS) composites in relation with morphological aspects revealed by atomic force microscopy (AFM) was investigated in this article. SEBS hindered the crystallization process of PP in PP/NS composites, leading to a smaller degree of crystallinity and lower perfection of crystalline structure. Broader lamellar thickness distribution was obtained in nanocomposites containing SEBS. Almost two times higher dielectric loss as compared to PP reference and two relaxation processes were detected in εr ′′(f) curves of nanocomposites. The first peak, in the same frequency domain as for the references, was assigned to α‐relaxation of polymer components together with interfacial polarization. The relaxation time follows the Arrhenius law with an activation energy of 80–90 kJ/mol. For the second process, the temperature dependence of the relaxation times obeyed the VFT equation. The dielectric changes following the incorporation of SEBS support its tendency to hinder the motional processes in PP, in accordance with DSC results. A smooth transition from a phase rich in SEBS to one containing mainly PP was detected in the AFM image of the composite with the larger amount of SEBS, emphasizing the good compatibility at the PP/SEBS interface. POLYM. ENG. SCI., 53:2081–2092, 2013. © 2013 Society of Plastics Engineers 相似文献
58.
This paper provides a resource-based assessment of availability of biomass resources for energy production in Romania, at NUTS-3 level. The estimation of available biomass includes the residues generated from crop production, pruning of vineyards and orchards, forestry operations and wood processing. The estimation of crop residue availability considers several site-specific factors such as crop yields, multi-annual yield variation, environmental constraints and competitive uses. The evaluation of agricultural residues was based on specific residue to product ratios, depending on crop type and crop yield. An estimate of pruning residues is proposed, based on current orchard and vineyard areas and specific ratios of residues. Woody biomass considers forest and forestry residues (including firewood) and wood processing by-products, taking into account the type and share of the unused part of the tree biomass and technical and economic aspects, including availability and competitive use. The amount of agricultural and forest residues available for bioenergy in Romania was estimated at 228.1 PJ on average, of which 137.1 PJ was from annual crop residues, 17.3 PJ residues from permanent crops and 73.7 PJ/year from forestry residues, firewood and wood processing by-products. The biomass availability shows large annual and spatial variations, between 135.6 and 320.0 PJ, due to the variation in crop production and forestry operations. This variation, which is even larger at the NUTS-3 level, if not properly considered may result in shortages in biomass supply in some years, when biomass is available in a lower amount than the average. 相似文献
59.
The paper approaches the half-century history and the main research results of the academic staff and researchers from “Politehnica” University of Timisoara (Universitatea “Politehnica” Timisoara—UPT) and their collaboration with the academic, research and production environment concerning the use of induction machine as power supply in microhydro plants and windmills in particular; from among these collaborators we mention: The Romanian Academy—Timisoara Branch, The Institute for Automation IPA—Timisoara Branch, The Research and Modernization Institute for Energetics ICEMENERG Bucharest, The National Institute for Heat Engines INMT Bucharest, The Machine Construction Works UCMR—Resita, “Electroputere” Works—Craiova and “Electromotor” Works—Timisoara.The paper aims at presenting the original research results at UPT against the background of general research from all over the world focused on revival the induction generator by automation. 相似文献
60.
Nicolae Tomozeiu 《Thin solid films》2007,515(16):6582-6585
Silicon oxide (a-SiO) is one of the most used silicon-based materials in optoelectronic and microelectronic technology. It is well-known that the electronic properties are linked to the material structure, which depends on the deposition technique and on the details of the deposition. Silicon suboxide (a-SiOx 0 < x < 2) layers were prepared by r.f. magnetron-sputtering from a polycrystalline silicon target in a well defined oxidation environment.Optical Emission Spectroscopy (OES) was employed to study the plasma used in SiOx depositions. Theoretical calculations performed in the frame of electron impact excitation mechanism for argon and atomic oxygen corroborated with electron impact dissociation of the molecular oxygen have shown the strong influence of the electron temperature on the rate coefficients of photons' production.Correlation functions between the OES signals assigned to silicon and oxygen atoms from plasma (gas phase) and the SiOx layer composition (infrared and energy dispersive X-ray investigated) have been found. Based on these functions, the OES plasma monitoring is proposed as a tool to control in-situ and in direct time the SiOx layer composition. 相似文献