441 research outputs found
A dynamic thermoviscoelastic contact problem with the second sound effect
No full textThis paper deals with a contact problem describing the mechanical and thermal
evolution of a damped extensible thermoviscoelastic beam under the Cattaneo law,
relating the heat flux to the gradient of the temperature. The beam is rigidly
clamped at its left end whereas the right end of the beam moves vertically between
reactive stops like a nonlinear spring. Existence and uniqueness of the solution is
proved, as well as the exponential decay of the related energy. Then, fully discrete
approximations are introduced by using the classical finite element method and the
implicit Euler scheme to approximate the spatial variable and to discretize the time
derivatives, respectively. An a priori error estimates result is proved, from which the
linear convergence of the algorithm is deduced. The case where the two stops are
rigid is also studied from the point of view of the existence and longtime behavior
of the solutions. Finally, some numerical simulations are presented to demonstrate
the accuracy of the approximation and the behavior of the solutio
James Mim
No full textabstract: James left his home in 1988 and reached Etang in Ethiopia in 1989.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Region: BentiwThis picture and bio was donated to the "Lost Boys Found" oral history project from The Arizona Lost Boys Cente
Estudio de la influencia de la morfología y de la distribución de tamaños de partícula del polvo en la obtención de aleaciones base Cu y base Ni mediante la tecnología MIM
No full textEn las últimas dos décadas, el procesado mediante moldeo por inyección de polvos metálicos (MIM) ha sido una tecnología que ha experimentado un notable crecimiento año tras año debido a que constituye una alternativa rentable para la fabricación de piezas de pequeño tamaño y difícil geometría. Sin embargo, una de sus mayores limitaciones como tecnología es el alto coste que presentan los polvos metálicos con morfología esférica y pequeño tamaño de partícula que se utilizan normalmente en esta ruta de procesado. En el presente trabajo de investigación se ha estudiado la influencia de la morfología del polvo metálico y de la distribución de tamaños de partícula del mismo sobre cada una de las etapas que constituyen el procesado MIM. El objetivo principal es determinar la viabilidad de la sustitución total o parcial del tipo de polvo que se utiliza actualmente (atomizado en gas) por otros tipos de polvo más económicos. Para llevar a cabo este estudio, se seleccionaron dos materiales metálicos cuyo procesado mediante MIM presentara interés industrial. Se eligió un bronce (90Cu/10Sn) y una superaleación base níquel (Inconel 718). Ambos materiales fueron mezclados con un ligante formado por polietileno de alta densidad (HDPE) y cera parafínica utilizando además, en el caso del Inconel 718, ácido esteárico como agente surfactante. Este sistema ligante multicomponente es económicamente asequible y su abastecimiento está garantizado en el tiempo por lo que constituye una solución adecuada para su aplicación industrial. En la fabricación de las mezclas polvo-ligante se han utilizado polvos de diferente geometría y distribuciones de tamaño de partícula distinta. Por un lado se busca reducir el precio del “feedstock” (mezcla polvo-ligante) y, por otro, aumentar el empaquetamiento para reducir la viscosidad de las mezclas consiguiendo de este modo aumentar la carga sólida y mejorar el control dimensional sobre los componentes. Medidas reológicas y del par de torsión permitieron evaluar el contenido de polvo óptimo de cada mezcla polvoligante para llevar a cabo el proceso de moldeo del material. Además, el estudio de diferentes parámetros reológicos como la viscosidad, el índice de flujo, la energía de activación y el esfuerzo umbral ha permitido determinar cómo influye la morfología y distribución de tamaños de partícula del polvo sobre su procesabilidad. Una vez determinados los contenidos de polvo óptimos en cada caso, se procedió a la fabricación de componentes en verde (formados por el polvo metálico y el ligante) mediante moldeo por inyección de las diferentes mezclas. Para realizar una inyección satisfactoria fue necesario optimizar parámetros como la temperatura, el volumen, la presión y el flujo de inyección de modo que las piezas obtenidas no presentaran defectos de fabricación y fueran lo suficientemente resistentes para soportar la manipulación necesaria en las etapas posteriores. Al mismo tiempo, se estudió la facilidad de procesado de cada mezcla relacionándola con las características del polvo utilizado en cada caso. A continuación, se intentó determinar cuáles eran las técnicas de eliminación del ligante más convenientes teniendo en cuenta los materiales y los sistemas ligantes utilizados. A través de la caracterización térmica (TGA, DSC) del sistema ligante y de los “feedstocks” fabricados, se definieron las condiciones más adecuadas para llevar a cabo el proceso y, del mismo modo que en los casos anteriores, se estudió cómo influyen las características del polvo en el proceso de eliminación. Finalmente, se realizó la sinterización de los materiales, determinando las condiciones óptimas del proceso. Las piezas obtenidas fueron estudiadas evaluando algunas propiedades físicas y mecánicas como la densidad, porosidad y la dureza. Tanto el proceso de sinterización como las propiedades finales fueron relacionados con las características del polvo de partida. ________________________________________________In the present Ph. D thesis, the influence of particle morphology and size distribution
of the powder on the different stages of Powder Injection Moulding process (PIM) has
been investigated. The aim of this work is to determine the optimal powder characteristics
to carry out the process, just as to study the viability of the total or partial replacing of the
gas atomised powder, nowadays used in this technology, with other kinds of more
economical powders.
The study was performed using different bronze (90Cu/10Sn) and superalloy Inconel
718 powders in order to fabricate powder-binder mixtures employing different particle
morphologies and particle size distributions.
The rheological properties determination of the powder-binder mixtures allowed
knowing the optimal solids loading for the green components fabrication through injection
moulding. Next, the more convenient conditions to carry out the binder elimination process
were established and sintering of the materials was performed under different
atmospheres and thermal cycles. Finally, the sintered components were characterized and
the results were compared having into account the features of the powder used for their
fabrication
Uma leitura dos modos de vida e do trabalho fabril no romance De mim já nem se lembra, de Luiz Ruffato
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Literatura, Florianópolis, 2015.Esta dissertação tem como objetivo fazer uma leitura dos modos de vida e do trabalho fabril no romance De mim já nem se lembra (2007) de Luiz Ruffato. Entre os temas abordados por esse escritor estão questões relacionadas com a migração de trabalhadores do campo para a cidade em busca de uma melhor perspectiva de vida. É nesse contexto que os personagens de Ruffato irão se deparar com o trabalho fabril nas metalúrgicas das grandes metrópoles e, em função disso, terão sua cultura, identidade e modos de existência alterados em relação à vida que possuíam no interior. Pretendemos por meio do estudo da literatura, da história e da sociologia, abrir caminhos para uma melhor compreensão dessa narrativa de Luiz Ruffato.Abstract : This thesis aims to make a reading of livelihoods and factory work in the novel De mim já nem se lembra (2007) of Luiz Ruffato. Among the topics covered by this author are issues related to migration of rural workers to the city in search of a better outlook on life. In this context, the Ruffato characters will face the work on metallurgical factories in the big cities and, on that basis, will have their culture, identity and livelihoods changed in comparison to their earlier life in countryside. We intend through the study of literature, history and sociology, open ways for a better understanding of this Luiz Ruffato narrative
Methods of reliability assessment of heterogeneous redundant systems
No full textAccepted Author ManuscriptTransport Engineering and Logistic
Identification of radiolytic products of [C(4)mim][NTf2] and their effects on the Sr2+ extraction
No full textThe trace water-soluble radiolytic products of neat 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ([C(4)mim][NTf2]) were identified by analysing water-washed samples of.-ray irradiated ionic liquids. CF3SO2OH, CF3SOOH, CF3SO2NH2, HF and H2SO3 were confirmed as main radiolytic products of [C(4)mim][NTf2], and the total radiation chemical yields of the water-soluble radiolytic products (0.35 mu mol J(-1)) and that of hydrogen ions (0.46 +/- 0.02 mu mol J(-1)) were determined by using ion chromatography and neutralization titration, respectively. It was found that the water-soluble radiolytic products of [C(4)mim][NTf2] greatly reduced the extraction efficiency of Sr2+ from water to irradiated [C(4)mim][NTf2], while the waterinsoluble radiolytic products of [C(4)mim][NTf2] had a slight influence on the Sr2+ extraction.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000315351800026&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, Inorganic & NuclearSCI(E)EIPubMed11ARTICLE124299-43054
MIM Isa Valley, 1995 Gravity Survey, Qld (P199541), gravity point data
No full textMaintenance and Update Frequency: notPlannedStatement: This MIM Isa Valley, 1995 Gravity Survey, Qld (P199541), gravity point data contains ground gravity point data for the MIM Isa Valley, 1995 Gravity Survey, Qld (P199541) survey acquired for MIM Holdings Ltd. This dataset contains a total of 1600 point data values. The data is located in QLD and were acquired in 1995. The point located data were collected in irregular traverses layout at a station spacing between 50 and 2000 metres.
Terrain corrections were calculated using the INTREPID Geophysics software package. The processed data are checked by GA geophysicists using standard methods for assessing quality to ensure that the final data are fit-for-purpose.
All data are provided in EPSG:4283 coordinates, Australian Height Datum (AHD) and gravity datum of AAGD07. The units are degrees, meters, and micrometres per second squared, respectively.
Reference:
Intrepid Geophysics, http://www.intrepid-geophysics.com.Gravity data measures small changes in gravity due to changes in the density of rocks beneath the Earth's surface. The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose.<br/> This MIM Isa Valley, 1995 Gravity Survey, Qld (P199541) contains a total of 1600 point data values acquired at a spacing between 50 and 2000 metres. The data is located in QLD and were acquired in 1995, under project No. 199541 for MIM Holdings Ltd
MIM Mt Isa Inlier percent potassium grid geodetic
No full textMaintenance and Update Frequency: notPlannedStatement: This MIM Mt Isa Inlier percent potassium grid geodetic is an airborne-derived radiometric potassium grid for the MIM Data from Mt Isa Inlier, QLD. The survey was acquired under the project No. 1029 for the geological survey of QLD. The grid has a cell size of 0.00042 degrees (approximately 45m). A total of 676318 line-kilometres of data at a line spacing between 200m and 400m, and 80m terrain clearance were acquired to produce this grid. This radiometric potassium grid shows potassium element concentration of the MIM Data from Mt Isa Inlier, QLD in units of percent (or %). Noise-adjusted singular value decomposition (NASVD) has been applied to the data. NASVD is a spectral component analysis procedure for the removal of noise from gamma-ray spectra. Details of the specifications of individual airborne surveys can be found in the Fourteenth Edition of the Index of Airborne Geophysical Surveys (Percival, 2014). This Index is also available online at http://pid.geoscience.gov.au/dataset/79134.
Reference:
Percival, P.J., 2014. Index of airborne geophysical surveys (Fourteenth Edition).The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth's surface as the result of the natural radioactive decay of potassium (K), uranium (U) and thorium (Th). The data collected are processed via standard methods to ensure the response recorded is that due only to the rocks in the ground. The results produce datasets that can be interpreted to reveal the geological structure of the sub-surface. The processed data is checked for quality by GA geophysicists to ensure that the final data released by GA are fit-for-purpose.<br/>This radiometric potassium grid has a cell size of 0.00042 degrees (approximately 45m) and shows potassium element concentration of the MIM Data from Mt Isa Inlier, QLD in units of percent (or %). The data used to produce this grid was acquired in 1990 by the QLD Government, and consisted of 676318 line-kilometres of data at a line spacing between 200m and 400m, and 80m terrain clearance
gamma-Radiation effect on Th4+ extraction behaviour of TODGA/[C(2)mim][NTf2]: identification and extractability study of radiolytic products
No full textThe gamma-radiation effect on Th4+ extraction by N,N,N',N'-tetraoctyldiglycolamide (TODGA)/1-ethyl-3-methylimidazoliumbis (trifluoromethylsulfonyl)imide ([C(2)mim][NTf2]) and TODGA/dodecane was evaluated through the quantitative analysis of TODGA content and identification of the radiolytic products. In addition, the density functional theory (DFT) calculations of extractability for the first time. The Th4+ partitioning of TODGA/[C(2)mim][NTf2] from 0.01 M HNO3 was near 98.6% at 1000 kGy, which was much higher than that in TODGA/dodecane (16.3%). The content of TODGA in diluent after irradiation was quantified using UPLC-Q-TOF-MS. The results showed that the [C(2)mim][NTf2] did not have the ability to protect the TODGA molecular comparing with the dodecane. However, TODGA in [C(2)mim][NTf2] prefers to react with the [C(2)mim](+) radical under g-radiation, and that in dodecane prefers degradation according to radiolytic products identification. Moreover, the DFT calculations presented that the substituted compounds formed in TODGA/[C(2)mim][NTf2] was responsible for partially keeping the extraction ability for Th4+.Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning; National Natural Science Foundation of China [11475112, 91426302]; Innovation Foundation of Institute of Nuclear Physics and Chemistry [2015CX04]; Ph.D. Programs Foundation of Ministry of Education of China [20130073120051]SCI(E)[email protected]; [email protected]
High performance optical systems using mim based plasmonic structures
No full text© 2017 The Author(s). In this paper, the design of high performance optical systems based on MIM based plasmonic structures is proposed. Using a design methodology based on optimization functions, two novel components are proposed: demultiplexer and gas sensor. Further optimization of these plasmonic systems, high performance optical demultiplexer is maintained with a narrow line-width down to 4 nm with acceptable power level around 30%. On the other side, highly sensitive optical sensor is proposed with sensitivity up to 2000 nm and a limit of detection down to 10−4
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