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Search Results: 1 - 10 of 223954 matches for " R. Mola "
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Fabrication and Microstructure of Layers Containing Intermetallic Phases on Magnesium
R. Mola
Archives of Foundry Engineering , 2013,
Abstract: Al- and Al/Zn-enriched layers containing intermetallic phases were deposited on the Mg substrate by heating the Mg specimens in contactwith the powdered materials in a vacuum furnace. The Al-enriched surface layers were produced using Al powder, whereas the Al/Znenriched layers were obtained from an 80 wt.% Al + 20 wt.% Zn powder mixture. The microstructure and composition of the layers wereanalyzed by optical microscopy, scanning electron microscopy and X-ray diffraction. The results showed that the Al-enriched layercomprised an Mg17Al12 intermetallic phase and a solid solution of Al in Mg. The layer obtained from the Al+Zn powder mixture wascomposed of Mg-Al-Zn intermetalic phases and a solid solution of Al and Zn in Mg. Adding 20% of Zn into the Al powder resulted in theformation of a considerably thicker layer. Moreover, the hardness of the surface layers was much higher than that of the Mg substrate.
Formation of magnesium-eutectic mixture layered composite
R. Mola,A. Dziadoń
Archives of Foundry Engineering , 2008,
Abstract: The work was started from study of the structural transformations, that in elevated temperatures, take place at the magnesium-aluminium interface. It was found experimentally that at temperature of 445oC solid state diffusion is followed by liquid phase appearance at the Mg-Al interface. For process passing with the liquid phase contribution thickness d of the reactions products against the time t can be expressed by the equation d=Atn with the time exponent value n>1. This process is very fast compared to solid state polyphase diffusion and can be controlled, therefore may be used for fabrication of layered composite. To obtain a composite, magnesium and aluminium sheets are formed alternately into a pocket and then heated at temperature of 445oC. Heating is prolonged for passing all the aluminium with part of the magnesium sheets into a liquid phase. During solidification liquid phase is transformed into eutectic mixture. So, composite that was formed consists of alternating magnesium and eutectic mixture layers. Using X-ray microprobe analysis and on the basis of Mg-Al binary phase diagram we were found that the eutectic mixture contains two phases: Mg17Al12 intermetallic compound and solid solution of aluminium in magnesium.
Analysis of the Inconel 600 alloy destruction process in the surrounding of oxygen, nitrogen and hydrogen
M. Gajewski,J. Kasińska,R. Mola
Archives of Foundry Engineering , 2010,
Abstract: This paper presents results of research, which was targeted to define reasons of the short life of sieves made from a 0.8mm diameter wireof the INCONEL 600 alloy. It was noticed that when the sieves were used in the device for the nitrogen acid production there appeared atotal loss of plastic properties of the wire. It was caused by the process of diffusion of oxygen, nitrogen and metal ions which was notstopped although the protective layer of the scale was produced. It resulted in the substantial decrease of the chromium contents (to ca1.5%) and in oxidation of the grain boundary in the wire outer layer. The diffusion of nitrogen to the wire core caused in turn theprecipitation of many Cr2N nitrides in the core.
Dendritic flux jumps in an organic superconducting crystal
M. M. Mola,R. Haddad,S. Hill
Physics , 2004,
Abstract: Angle dependent torque measurements have been carried out on the organic superconductor, kappa-(ET)2Cu(NCS)2 at extremely low temperatures (25 - 300 mK). Magneto-thermal instabilities are observed in the form of abrupt magnetization (flux) jumps for magnetic field sweeps of 0 - 20 tesla. A fractal analysis of the flux jumps indicates that the instabilities do show a self similar structure with a fractal dimension varying between 1.15 - 1.6. The fractal structure of the flux jumps in our sample shows a stricking similarity to that of MgB2 thin film samples, in which magneto-optical experiments have recently shown that the small flux jumps are due to the formation of dendritic flux structures. These smaller instabilities act to suppress the critical current density of these thin films. The similarity of the flux jump structure of our samples suggests that we are also observing the dendritic instability, but in a bulk sample rather than a thin film. This is the first observation of the dendritic instability in a bulk superconducing sample, and is likely due to the layered nature of kappa-(ET)2Cu(NCS)2, which results in a quasi-two dimensional flux structure over the majority of it's mixed state phase diagram.
Towards Cloud Management by Autonomic Manager Collaboration  [PDF]
Omid Mola, Michael A. Bauer
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.432097
Abstract: The management of clouds comprised of hundreds of hosts and virtual machines present challenging problems to administrators in ensuring that performance agreements are met and that resources are efficiently utilized. Automated approaches can help in managing such environments. Autonomic managers using policy-based management can provide a useful approach to such automation. We outline how collections of collaborating autonomic managers in cloud can be a step towards better management of clouds. We describe how a hierarchy of policy-based autonomic managers can collaborate using messages. The messages and when to communicate is inferred automatically from the policies given to the managers. We evaluate the approach via a prototype inspired by a cloud virtualized infrastructure and show how collaboration between managers in a hierarchy can improve the response time of a web server and avoid service level agreement violations. Results of three different scenarios shows the importance of collaboration between managers at different authority levels and how this collaboration can help to increase efficiency of current infrastructures.
Seasonal and spatial distribution of Brachionus (Pallas, 1966; Eurotatoria: Monogonanta: Brachionidae), a bioindicator of eutrophication in lake El-Manzalah, Egypt
HRA. Mola
Biology and Medicine , 2011,
Abstract: Rotifers, especially Brachionus sp., are the major component of zooplankton in Egyptian eutrophic lakes. Thesespecies play an important role as bioindicator in these aquatic environments. In present study, twenty-fourzooplankton samples were collected and investigated along six stations of southeastern sector of the lake fromAugust 2009 to May 2010. Brachionus sp. were the most abundant species constituting 74.8 % of the total rotifersand 59.87 % of the total zooplankton. It was represented by 7 species which are; Brachionus angularis, B.budapestinensis, B. calyciflorus, B. caudatus, B. plicatilis, B. urceolaris and B. quadridentatus. The highestabundance of Brachionus sp. was recorded at Ibn Salam Station (4227493 Org./m3) during summer due to the effectof water discharge rich in nutrients through 3 main drains in this area while the lowest abundance was recorded at El-Qaboti Station (333 Org./m3) during winter. Brachionus angularis and B. calyciflorus formed collectively (92.16 % ofthe total Brachionus sp.). The presence of these species of Brachionus in high composition indicates eutrophicationof Lake El-Manzalah.
Convergence to equilibria for a three-dimensional conserved phase-field system with memory
Gianluca Mola
Electronic Journal of Differential Equations , 2008,
Abstract: We consider a conserved phase-field system with thermal memory on a tridimensional bounded domain. Assuming that the nonlinearity is real analytic, we use a Lojasiewicz-Simon type inequality to study the convergence to steady states of single trajectories. We also give an estimate of the convergence rate.
Variaciones meióticas y evolución cromosómica en insectos y arácnidos con cromosomas holocinéticos
Mola,L. M; Rebagliati,P. J; Rodríguez Gil,S. G; Adilardi,R. S;
BAG. Journal of basic and applied genetics , 2011,
Abstract: cytogenetic studies in model groups of insects (odonata and heteroptera) and arachnids (dysderoidea and buthidae) with holokinetic chromosomes allowed us to identify differences in autosomes and sex chromosomes meiotic behaviour (pre-or post-reductional meiosis, chiasmatic or achiasmatic meiosis, telokinetic or holokinetic activity). also, we detected differences in the frequency and distribution of chromosomal mutations (fusions, fragmentations and translocations both in homozygosity or heterozygosity) in the karyotype evolution mechanisms.
Fantasia e conhecimento: um estudo crítico preliminar
Mola, Luis Guilherme Coelho;
Psicologia USP , 1999, DOI: 10.1590/S0103-65641999000200003
Abstract: the purpose of this article is to discuss the role played by imagination in the process of knowledge production. using as theoretical support the ideas of some philosophers of the frankfurt school, the text attempts to demonstrate that imagination has a critical function, denied by positivism, which could contribute for the questioning of the organization of society.
L'ús de la norma de qualitat ISO 9001 a les biblioteques d'institucions d'educació superior
Balagué Mola, Núria
BiD : Textos Universitaris de Biblioteconomia i Documentació , 2007,
Abstract: La norma ISO 9001 és un dels instruments de gestió que han estat adoptats per les biblioteques durant els darrers anys. En aquest article es presenten els trets principals de les biblioteques d'institucions d'ensenyament superior que han assolit la certificació dels seus sistemes de gestió de la qualitat amb la norma ISO 9001:2000, els motius que les han dut a certificar-se, i els avantatges i les dificultats que els ha comportat aplicar-la. Finalment, s'ofereix una visió prospectiva sobre el futur de la norma ISO 9001 a les biblioteques universitàries.Las norma ISO 9001 es uno de los instrumentos de gestión que han sido adoptados por las bibliotecas durante los últimos a os. En este artículo se presentan las principales características de las bibliotecas de instituciones de ense anza superior que han obtenido la certificación de su sistema de gestión de la calidad con la norma ISO 9001:2000, los motivos que las han llevado a certificarse, y las ventajas y dificultades que les ha supuesto su aplicación. Finalmente, se ofrece una visión prospectiva sobre el futuro de la norma ISO 9001 en las bibliotecas universitarias.ISO standard 9001 is one of a set of management tools that libraries have adopted in recent years. This article focuses on libraries in higher education institutions that have received ISO certification of their quality management systems (ISO standard 9001:2000). We examine their reasons for seeking certification and the advantages and difficulties they have encountered in applying this ISO standard. Finally, we consider the future prospects of ISO standard 9001 in university libraries.
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