979 resultados para flash welding


Relevância:

20.00% 20.00%

Publicador:

Resumo:

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PURPOSE. To establish the optimal flash settings for retinal vessel oxygen saturation parameters using dual-wavelength imaging in a multiethnic group. METHODS. Twelve healthy young subjects (mean age 32 years [SD 7]; three Mediterranean, two South Asian, and seven Caucasian individuals) underwent retinal vessel oxygen saturation measurements using dual-wavelength oximetry, noncontact tonometry, and manual sphygmomanometry. In order to evaluate the impact of flash intensity, we obtained three images (fundus camera angle 30°, ONH centered) per flash setting. Flash settings of the fundus camera were increased in steps of 2 (initial setting of 6 and the final of 22), which reflect logarithmic increasing intensities from 13.5 to 214 Watt seconds (Ws). RESULTS. Flash settings below 27 Ws were too low to obtain saturation measurements, whereas flash settings of more than 214 Ws resulted in overexposed images. Retinal arteriolar and venular oxygen saturation was comparable at flash settings of 27 to 76 Ws (arterioles' range: 85%-92%; venules' range: 45%-53%). Higher flash settings lead to increased saturation measurements in both retinal arterioles (up to 110%) and venules (up to 92%), with a more pronounced increase in venules. CONCLUSIONS. Flash intensity has a significant impact on retinal vessel oxygen saturation measurements using dual-wavelength retinal oximetry. High flash intensities lead to supranormal oxygen saturation measurements with a magnified effect in retinal venules compared with arteries. In addition to even retinal illumination, the correct flash setting is of paramount importance for clinical acquisition of images in retinal oximetry. We recommend flash settings between 27 to 76 Ws. © 2013 The Association for Research in Vision and Ophthalmology, Inc.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper investigates distortions and residual stresses induced in butt joint of thin plates using Metal Inert Gas welding. A moving distributed heat source model based on Goldak's double-ellipsoid heat flux distribution is implemented in Finite Element (FE) simulation of the welding process. Thermo-elastic-plastic FE methods are applied to modelling thermal and mechanical behaviour of the welded plate during the welding process. Prediction of temperature variations, fusion zone and heat affected zone as well as longitudinal and transverse shrinkage, angular distortion, and residual stress is obtained. FE analysis results of welding distortions are compared with existing experimental and empirical predictions. The welding speed and plate thickness are shown to have considerable effects on welding distortions and residual stresses. © 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A successful and useful treatment for end-stage heart failure is Left ventricular assist device (LVAD). An important part - a hydrodynamically suspended impeller exposed to corrosive conditions, required to sealed hermetically into micro packages. Laser beam welded (LBW) Ti6Al4V alloy has been adopted in anti-corrosion micro packages for the impeller of a (LVAD). Thin and narrow welds were required for such medical equipment. Pulsed Nd:YAG welding was successfully adopted as sealing method for the impeller. ©2011 IEEE.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Currently the data storage industry is facing huge challenges with respect to the conventional method of recording data known as longitudinal magnetic recording. This technology is fast approaching a fundamental physical limit, known as the superparamagnetic limit. A unique way of deferring the superparamagnetic limit incorporates the patterning of magnetic media. This method exploits the use of lithography tools to predetermine the areal density. Various nanofabrication schemes are employed to pattern the magnetic material are Focus Ion Beam (FIB), E-beam Lithography (EBL), UV-Optical Lithography (UVL), Self-assembled Media Synthesis and Nanoimprint Lithography (NIL). Although there are many challenges to manufacturing patterned media, the large potential gains offered in terms of areal density make it one of the most promising new technologies on the horizon for future hard disk drives. Thus, this dissertation contributes to the development of future alternative data storage devices and deferring the superparamagnetic limit by designing and characterizing patterned magnetic media using a novel nanoimprint replication process called "Step and Flash Imprint lithography". As opposed to hot embossing and other high temperature-low pressure processes, SFIL can be performed at low pressure and room temperature. Initial experiments carried out, consisted of process flow design for the patterned structures on sputtered Ni-Fe thin films. The main one being the defectivity analysis for the SFIL process conducted by fabricating and testing devices of varying feature sizes (50 nm to 1 μm) and inspecting them optically as well as testing them electrically. Once the SFIL process was optimized, a number of Ni-Fe coated wafers were imprinted with a template having the patterned topography. A minimum feature size of 40 nm was obtained with varying pitch (1:1, 1:1.5, 1:2, and 1:3). The Characterization steps involved extensive SEM study at each processing step as well as Atomic Force Microscopy (AFM) and Magnetic Force Microscopy (MFM) analysis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study focused object a steam generation system, steam distribution and condensate return a textile plant located in Rio Grande do Norte. The work was based on the following objectives: Knowing the use of saturated water vapor in the dyeing and finishing processes in a textile plant; To study the various aspects of a steam distribution system to identify the ways in which energy losses occur; Obtain quantitative information of the main loss in steam generation system and steam distribution and to measure the losses, water and steam system; Using the flash steam as a means of cost reduction. For it was made use of the calculation of financial gains made in their respective improvements. As a database for the development of working registers are used in industrial processes, data from utility systems, laboratory data analysis and on-line analyzers, covering the period 2013. Using the principles set conservation laws mass and energy, those data showed that the loss of water and energy in the steam system are significant and that the environmental and economic gains to be obtained with improvement actions are quite significant. Based on the data and results suggest that future studies deem the continuity approach to steam generation systems, distribution and mainly condensate return.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Google Docs (GD) is an online word processor with which multiple authors can work on the same document, in a synchronous or asynchronous manner, which can help develop the ability of writing in English (WEISSHEIMER; SOARES, 2012). As they write collaboratively, learners find more opportunities to notice the gaps in their written production, since they are exposed to more input from the fellow co-authors (WEISSHEIMER; BERGSLEITHNER; LEANDRO, 2012) and prioritize the process of text (re)construction instead of the concern with the final product, i.e., the final version of the text (LEANDRO; WEISSHEIMER; COOPER, 2013). Moreover, when it comes to second language (L2) learning, producing language enables the consolidation of existing knowledge as well as the internalization of new knowledge (SWAIN, 1985; 1993). Taking this into consideration, this mixed-method (DÖRNYEI, 2007) quasi-experimental (NUNAN, 1999) study aims at investigating the impact of collaborative writing through GD on the development of the writing skill in English and on the noticing of syntactic structures (SCHMIDT, 1990). Thirtyfour university students of English integrated the cohort of the study: twenty-five were assigned to the experimental group and nine were assigned to the control group. All learners went through a pre-test and a post-test so that we could measure their noticing of syntactic structures. Learners in the experimental group were exposed to a blended learning experience, in which they took reading and writing classes at the university and collaboratively wrote three pieces of flash fiction (a complete story told in a hundred words), outside the classroom, online through GD, during eleven weeks. Learners in the control group took reading and writing classes at the university but did not practice collaborative writing. The first and last stories produced by the learners in the experimental group were analysed in terms of grammatical accuracy, operationalized as the number of grammar errors per hundred words (SOUSA, 2014), and lexical density, which refers to the relationship between the number of words produced with lexical properties and the number of words produced with grammatical properties (WEISSHEIMER, 2007; MEHNERT, 1998). Additionally, learners in the experimental group answered an online questionnaire on the blended learning experience they were exposed to. The quantitative results showed that the collaborative task led to the production of more lexically dense texts over the 11 weeks. The noticing and grammatical accuracy results were different from what we expected; however, they provide us with insights on measurement issues, in the case of noticing, and on the participants‟ positive attitude towards collaborative writing with flash fiction. The qualitative results also shed light on the usefulness of computer-mediated collaborative writing in L2 learning.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Este trabalho propõe o estudo comparativo do uso de infográficos multimídia pelos sites Clarín.com, da Argentina e Folha.com, do Brasil. A pesquisa tem como objetivo verificar e analisar como esses dois importantes veículos de comunicação online da América Latina têm utilizado a tecnologia HTML5 para avançar nas possibilidades interativas do gênero jornalístico. Para tanto, a análise comparada trata da infografia multimídia, que tem passado por profundas mudanças tecnológicas, alterando o formato e o conteúdo da notícia. Além da conceituação teórica e revisão de literatura sobre infografia, newsgame, narrativa transmídia, jornalismo online, interatividade e as linguagens de programação voltadas para a produção de infografia multimídia, o trabalho realizou análise comparativa das seções Infográficos, veiculada pela Folha.com, e Especiales Multimedia, do Clarín.com. O estudo, quantitativo e qualitativo, verificou os recursos narrativos e informativos, ferramentas e tecnologias de linguagem de programação para Internet que são empregadas pelos dois meios de comunicação, com base no modelo de análise proposto por Alberto Cairo em Infografia 2.0 – visualización interactiva de información en prensa. A pesquisa demonstrou que ainda que o Clarín.com tenha utilizado a tecnologia Flash na maioria dos infográficos multimídia analisados, os resultados da análise comparada mostram que os infográficos do jornal online argentino possibilitaram níveis mais elevados de interatividade do que os infográficos multimídia da Folha.com, desenvolvidos majoritariamente em HTML5.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM), a promising electrolyte material for intermediate temperature solid oxide fuel cells, can be sintered to a fully dense state by a flash-sintering technique. In this work, LSGM is sintered by the current-limiting flash-sintering process at 690°C under an electric field of 100 V cm-1, in comparison with up to 1400°C or even higher temperature in conventional furnace sintering. The resultant LSGM samples are investigated by scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The SEM images exhibit well-densified microstructures while XRD results show that the perovskite structure after flash-sintering does not changed. EIS results show that the conductivity of LSGM sintered by the current-limiting flash-sintering process increases with sintering current density value. The conductivity of samples sintered at 120 mA mm-2 reaches 0.049 σ cm-1 at 800°C, which is approximate to the value of conventional sintered LSGM samples at 1400°C. Additionally, the flash-sintering process is interpreted by Joule heating theory. Therefore, the current-limiting flash-sintering technique is proved to be an energy-efficient and eligible approach for the densification of LSGM and other materials requiring high sintering temperature.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Lo scopo di questo lavoro di tesi è stato quello di studiare l’efficacia e l’applicabilità dello strumento HERACLES II Flash Gas Chromatography Electronic Nose mediante l’analisi di un set molto ampio di campioni di oli d’oliva vergini reperiti presso un concorso nazionale. Nello specifico, mediante elaborazioni di statistica multivariata dei dati, è stata valutata sia la capacità discriminante del metodo per campioni caratterizzati da un diverso profilo sensoriale, sia la correlazione esistente tra l’intensità delle sensazioni percepite per via sensoriale ed i dati ottenuti mediante l’analisi strumentale. La valutazione delle caratteristiche sensoriali dei campioni è stata realizzata in occasione dello stesso concorso da parte di un gruppo di giudici esperti e secondo le modalità stabilite dai regolamenti comunitari. Ogni campione è stato valutato da almeno 8 assaggiatori che hanno determinato l’intensità di caratteristiche olfattive (eventuali difetti, fruttato e note secondarie positive) e gustative (amaro e piccante). La determinazione dei composti volatili, invece, è stata condotta mediante lo strumento HERACLES II Electronic Nose (AlphaMOS), dotato di due colonne cromatografiche caratterizzate da diversa polarità (MXT-5 con fase stazionaria apolare e MXT-WAX con fase stazionaria polare), ciascuna collegata ad un rivelatore di tipo FID. L’elaborazione multivariata dei dati è stata realizzata mediante il software in dotazione con lo strumento.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The XML-based specification for Scalable Vector Graphics (SVG), sponsored by the World Wide Web consortium, allows for compact and descriptive vector graphics for the Web. SVG s domain of discourse is that of graphic primitives whose optional attributes express line thickness, fill patterns, text size and so on. These primitives have very different properties from those of traditional document components (e.g. sections, paragraphs etc.) that XML is normally called upon to express. This paper describes a set of three tools for creating SVG, either from first principles or via the conversion of existing formats. The ab initio generation of SVG is effected from a server-side CGI script, using a PERL library of drawing functions; later sections highlight the problems of converting Adobe PostScript and Macromedia s Shockwave format (SWF) into SVG.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In shipbuilding industry welding of primer coated and tack welded steel products cause different issues. Primer coated steel products are commonly used at shipyards to ensure corrosion free storage of products in outdoor conditions. However usage of primer can cause imperfections to welds. To prevent porosity primed steel products are usually welded with tubular welding wires. Tack welds cause commonly interferences in mechanized welding when over welded, which increases costs related to welding due to increased need of preparing and repairing. The aim of this study is to research possibilities of advanced solid wire MAG-welding processes to deal with these two previously mentioned problems. This study concentrates to examine possibilities of MAG-welding, pulse MAG-welding, double pulse MAG-welding, RapidArc and ForceArc processes. Large amount of experiments were made to find out the produced porosity and the ability to over weld tack welds with each process in different circumstances. In welding of primed steel products porosity is caused mainly by hydrogen, CO, CO2, nitrous gases and zinc fumes. It was found in experiments that porosity of MAG-welding can be greatly decreased by using pulse MAG-welding instead. Also reduction of welding speed, usage of air gap and usage of solid wire product with higher amount of alloying elements reduces porosity. Researched advanced MAG-welding processes did not have an improvement into over welding of tack welds. With studied throat thicknesses and welding positions conventional MAG-welding managed better over welding of tack welds than the four studied advanced MAG-welding processes. Studied solid wire MAG-welding processes would be best suited at shipyard for mechanized welding in welding position PB. In welding positions PD and PG tubular welding wires are clearly more productive.