2,171 research outputs found
Aunt Mag - 03
No full textPhotograph - Joe Irwin's Aunt Mag and other standing in front of a plane, likely the Gypsy Moth, [Calgary], Alberta. Left to right: Mrs. Emma Barton, Aunt Mag, Sister Jessie, Mrs. Bob Dingwall and her daughter, Grac
Aunt Mag
No full textPhotograph - Joe Irwin's Aunt Mag standing beside the Gypsy Moth, Great Western Airways, at Joe's first half hour dual instruction, Calgary, Albert
Mag and Agnes
No full textPhotograph - Joe Irwin's Aunt Mag and her oldest sister, Agnes. Vulcan, Albert
Space-Time Trellis and Space-Time Block Coding Versus Adaptive Modulation and Coding Aided OFDM for Wideband Channels
No full textAbstract—The achievable performance of channel coded spacetime trellis (STT) codes and space-time block (STB) codes transmitted over wideband channels is studied in the context of schemes having an effective throughput of 2 bits/symbol (BPS) and 3 BPS. At high implementational complexities, the best performance was typically provided by Alamouti’s unity-rate G2 code in both the 2-BPS and 3-BPS scenarios. However, if a low complexity implementation is sought, the 3-BPS 8PSK space-time trellis code outperfoms the G2 code. The G2 space-time block code is also combined with symbol-by-symbol adaptive orthogonal frequency division multiplex (AOFDM) modems and turbo convolutional channel codecs for enhancing the system’s performance. It was concluded that upon exploiting the diversity effect of the G2 space-time block code, the channel-induced fading effects are mitigated, and therefore, the benefits of adaptive modulation erode. In other words, once the time- and frequency-domain fades of the wideband channel have been counteracted by the diversity-aided G2 code, the benefits of adaptive modulation erode, and hence, it is sufficient to employ fixed-mode modems. Therefore, the low-complexity approach of mitigating the effects of fading can be viewed as employing a single-transmitter, single-receiver-based AOFDM modem. By contrast, it is sufficient to employ fixed-mode OFDM modems when the added complexity of a two-transmitter G2 scheme is affordable
Экологические проблемы при MIG/MAG-сварке
No full textВ данной статье рассматриваются основные экологические проблемы при проведении MIG/MAG-сварки. Дана характеристика сварочного процесса в зависимости от состава защитных газов. Автор приводит рекомендации по минимизации неблагоприятного воздействия MIG/MAG-сварки на здоровье сварщиков. This article discusses the main environmental problems when carrying out MIG/MAG welding. The characteristic of welding process depends on the composition of the protective gases. The author gives recommendations to minimize the adverse effects of MIG/MAG welding on the health of welders
Análise da influência dos gases de proteção no processo de soldagem mig/mag sobre distorções de chapas de aço
No full textTCC (graduação) – Universidade Federal de Santa Catarina. Centro de Engenharias da Mobilidade. Engenharia Naval.A indústria naval brasileira, devido aos crescentes investimentos principalmente no setor de petróleo e gás, encontra-se hoje em grande expansão com a construção de plataformas e embarcações de apoio a este setor. Os estaleiros brasileiros, para tornarem-se competitivos nesse cenário devem, portanto, apresentar constantes evoluções em seus processos. Visando ganho de produtividade, o processo de construção de embarcações é realizado pelo método de construção em blocos. Este consiste em montar a embarcação em várias partes, produzidas em suas oficinas para, posteriormente, serem unidos no picadeiro ou carreira para compor a embarcação como um todo. Estes blocos, em sua grande maioria, são fabricados a partir de chapas de aço enrijecidas reforçadas por vigas transversais e longitudinais, unidas por soldagem. Em estaleiros, o retrabalho durante a construção de embarcações é um fator a ser evitado, pois agrega custos adicionais e diminuição da produtividade. Uma grande fonte desses retrabalhos é, justamente, o problema de distorções nos painéis enrijecidos que compõem os blocos da embarcação. As distorções, causadas pelo aquecimento desigual dos painéis durante a soldagem, dificultam a posterior junção dos blocos devido à falta de alinhamento das partes. Deste modo, estes desvios na forma de projeto dos painéis necessitam ser corrigidos, implicando em maior tempo de trabalho. Desta forma, se torna pertinente o estudo dos efeitos que o processo de soldagem exerce sobre as distorções de estruturas metálicas. Neste contexto, o presente trabalho tem por intuito analisar a influência de diferentes composições de gases de proteção no processo MIG/MAG (Metal Inert Gas / Metal Active Gas) sobre as distorções de um modelo de corpo de prova em aço carbono ASTM A 569. Neste estudo foram realizados ensaios com as composições de gases de proteção Ar puro, Ar+5%O2, Ar+20%CO2+5%O2, Ar+15%CO2 e Ar+8%CO2. Os resultados indicaram a inexistência de qualquer efeito sobre as distorções oriundas da soldagem dentre os gases de proteção utilizados nos ensaios, evidenciando que a energia de soldagem é um fator determinante sobre estas.The Brazilian naval industry, mainly due to increasing investments in the oil and gas sector, is now booming with the construction of platforms and support vessels in this sector. To become competitive in this scenario, the Brazilian shipyards should therefore provide constant upgrades in it processes. In order gain in productivity, the vessel construction process is performed by the method of block building. This is, to assemble the craft in various parts, produced in their workshops, to later be joined in the drydock to render the vessel as a whole. These blocks, for the most part, are made from hardened steel plates reinforced by transverse and longitudinal beams, joined by welding. In shipyards, rework during construction vessels is a factor to be avoided because it adds additional costs and decreased productivity. A major source of these reworks is precisely the problem of distortions in stiff panels that make up the building blocks of the vessel. The distortions caused by uneven heating of the panels during welding, hinder the subsequent joining of the blocks due to misalignment of parts. Thus, these deviations in the design of the panels so need to be corrected, resulting in longer working time. Thus, it is pertinent to study the effects that the welding process has on the distortion of metal structures. In this context, this study is meant to examine the influence of different protective gas compositions in the MIG / MAG process (Metal Inert Gas / Metal Active Gas) on the distortions of a specimen model of carbon steel ASTM A 569. This study tests performed with the protective gas compositions of pure Ar, Ar+5%O2, Ar+20%CO2+5%O2, Ar+15%CO2 and Ar+8%CO2. The results indicated that there is no effect on the distortions arising from the welding shielding gases used in the tests, showing that the welding power is a determining factor on these
Improved productivity in fusion welding : executive summary
No full textThis document is an Executive Summary of individual submissions of work that the
author has submitted towards the degree of Engineering Doctorate. The work
comprises three main themes, which can be demonstrated in a broader sense as
contributing towards improved productivity in fusion welding:
i) The use of active fluxes for Tungsten Inert Gas (TIG) welding.
ii) An investigation into the reduction of porosity when Metal Active Gas (MAG)
welding galvanneal coated steel sheet used in the automotive industry.
iii) The use of high power Nd:YAG laser welding for the production of large
diameter, long distance land pipelines.
Active fluxes give improved productivity by increasing the penetration depth of the
TIG welding process by the simple addition of a flux applied to the surface.
Although the productivity benefits of the process had been proven through a joint
TWIIindustry project, the mechanism by which the fluxes produced this
improvement was not fully understood. The first theme investigated the mechanisms
at work in providing increased penetration and concluded that the primary
mechanism responsible for the action of the fluxes was not due to a change in the
flow of the molten pool but, as others had suggested, due to arc constriction. This
work contributed to a greater understanding of the welding process and,
furthermore, a greater understanding of the potential opportunities and limitations of
the process when designing new fluxes for other alloy systems.
MAG welds in coated steel sheet used in the automotive industry are prone to
porosity leading to high reject rates. The second phase of work reported here
determined welding procedures capable of delivering low porosity welds developed
through statistical experimental design. These procedures demonstrated how low
porosity welds could be made using conventional MAG welding techniques on
steels that had been galvanneal coated to provide corrosion resistance. The
procedures developed could be easily implemented at high production rates in an
industrial manufacturing environment to reduce defect levels, and thus costly repairs
or high scrap rates.
The third theme of the work demonstrated how Nd:YAG laser welding could
potentially be used to replace conventional arc welding techniques for land lay of
gas transmission pipelines. The application of a single laser fill pass, made at high
production rates, could replace the use of multiple MAG welding stations greatly
reducing the costs associated with pipeline fabrication. BP has claimed that half
pipeline cost savings of up to $300 million dollars are achievable through the
implementation of such a technique. The justification for the use of lasers in
pipelines is discussed in terms of both technical and economic suitability.
Preliminary experimental work showed that high power Nd:YAG laser welds could
achieve productivity targets, although in order to reduce defects and achieve the
necessary structural performance it would be necessary to combine laser welding
with a MAG welding process
Terminal suturing of Gondwana along the southern margin of South China Craton : evidence from detrital zircon U-Pb ages and Hf isotopes in Cambrian and Ordovician strata, Hainan Island
No full textThis work was supported by the National Natural Science Foundation of China (grants 41472086 and 41272120), “111” Project (B08030), the fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (CUG2012019240 and CUG2013019137). The first author also acknowledges China Scholarship Council (grant 201208420001) for supporting his research in the University of St. Andrews. Date of Acceptance: 20/11/2014Hainan Island, located near the southern end of mainland South China, consists of the Qiongzhong Block to the north and the Sanya Block to the south. In the Cambrian, these blocks were separated by an intervening ocean. U-Pb ages and Hf isotope compositions of detrital zircons from the Cambrian succession in the Sanya Block suggest that the unit contains detritus derived from late Paleoproterozoic and Mesoproterozoic units along the western margin of the West Australia Craton (e.g., Northampton Complex) or the Albany-Fraser-Wilkes orogen, which separates the West Australia and Mawson cratons. Thus, in the Cambrian the Sanya Block was not part of the South China Craton but rather part of the West Australian Craton and its environs. In contrast, overlying Late Ordovician strata display evidence for input of detritus from the Qiongzhong Block, which constituted part of the southeastern convergent plate margin of the South China Craton in the early Paleozoic. The evolving provenance record of the Cambrian and Ordovician strata suggests that the juxtaposition of South China and West Australian cratons occurred during the early to mid-Ordovician. The event was linked with the northern continuation of Kuungan Orogeny, with South China providing a record of final assembly of Gondwana.Peer reviewe
Molecular simulations on proteins of biomedical interest : A. Ligand-protein hydration B. Cytochrome P450 2D6 and 2C9 C. Myelin associated glycoprotein (MAG)
No full textTOPIC 1: Water molecules mediating polar interactions in ligand–protein complexes contribute to both binding affinity and specificity. To account for such water molecules in computer-aided drug discovery, we performed an extensive search in the Cambridge Structural Database (CSD) to identify the geometrical criteria defining interactions of water molecules with ligand and protein. In addition, ab initio calculations were used to derive the propensity of ligand hydration. Based on these information we developed an algorithm (AcquaAlta) to reproduce water molecules bridging polar interactions between ligand and protein moieties. This approach was validated using 20 crystal structures and yielded a match of 76% between experimental and calculated water positions. The solvation algorithm was then applied to the docking of oligopeptides to the periplasmic oligopeptide binding protein A (OppA), supported by a pharmacophore-based alignment tool.
TOPIC 2: Drug metabolism, toxicity, and interaction profile are major issues in the drug discovery and lead optimization processes. The Cytochromes P450 (CYPs) 2D6 and 2C9 are enzymes involved in the oxidative metabolism of a majority of the marketed drugs. By identifying the binding mode using pharmacophore pre-alignement and automated flexible docking, and quantifying the binding affinity by multi-dimensional QSAR, we validated a model family of 56 compounds (46 training, 10 test) and 85 (68 training, 17 test) for CYP2D6 and CYP2C9, respectively. The correlation with the experimental data (cross- validated r2 = 0.811 for CYP2D6 and 0.687 for CYP2C9) suggests that our approach is suited for predicting the binding affinity of compounds towards the CYP2D6 and CYP2C9. The models were challenged by Y-scrambling, and by testing an external dataset of binding compounds (15 compounds for CYP2D6 and 40 for CYP2C9) and not binding compounds (64 compounds for CYP2D6 and 56 for CYP2C9).
TOPIC 3: After injury, neurites from mammalian adult central nervous systems are inhibited to regenerate by inhibitory proteins such as the myelin-associated glycoprotein (MAG). The block of MAG with potent glycomimetic antagonists could be a fruitful approach to enhance axon regeneration. Libraries of MAG antagonists were derived and synthesized starting from the (general) sialic acid moiety. The binding data were rationalized by docking studies, molecular dynamics simulations and free energy perturbations on a homology model of MAG. The pharmacokinetic profile (i.e. stability in cerebrospinal fluid, logD, and blood-brain barrier permeation) of these compounds has been thoroughly investigated to evaluate the drug-likeness of the identified antagonists
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