131 research outputs found
Modelado Tridimensional y Análisis Funcional de una Cabria para la extracción del mineral
No full textQ3. Dyna. JCI(2023)=0.2En el presente artículo se analiza en detalle un ejemplo del patrimonio industrial minero del antiguo distrito minero de Linares-La Carolina (Jaén, España), como es una cabria de mampostería con su castillete metálico, utilizada en la extracción del mineral de plomo, concretamente de galena o sulfuro de plomo. En particular, se ha realizado el modelado tridimensional con ayuda de software paramétrico
gracias a técnicas empíricas de cada uno de los elementos que componen el conjunto. Asimismo, una vez obtenido el modelo 3D, se ha realizado un análisis funcional mediante técnicas de Ingeniería Asistida por Ordenador, basadas en el análisis tensional y el análisis de desplazamientos, comprobando que las mayores concentraciones de tensiones se producen en la parte media e inferior de los muros, que los
mayores valores de tensión se producen en los alrededores de los huecos de los muros, y que la mayor concentración de desplazamientos de la cabria de mampostería se encuentran en los muros en la parte media y superior, y del castillete en las correas de la cubierta.Nuestro agradecimiento más sincero al Ministerio de Economía y Competitividad, como organismo fi nanciador del Proyecto de Investigación del Plan Nacional de I+D+i titulado ‘El patrimonio histórico industrial minero: un estudio integral para su puesta en valor y difusión desde la ingeniería gráfica” (HAR2012-30723), así como al Programa Nacional de Formación del Profesorado Universitario (FPU) del Ministerio de Educación, Cultura y Deporte, ambos del Gobierno de España
Electrostrictive Deformations in Small Carbon Clusters, Hydrocarbon Molecules and Carbon Nanotubes
No full textCould [18]F-fluorodeoxyglucose PET/CT change the therapeutic management of stage IV thyroid cancer with positive (131)I whole body scan?
No full textStage-IV differentiated thyroid cancer (DTC) patients may present elevated serum thyroglobulin (Tg) levels associated with positive [(131)I] whole-body-scan (WBS). Nevertheless some patients in whom WBS does not reveal new sites of disease show increased Tg levels. This finding prompts thorough restaging in order to exclude the presence of metastases unable to concentrate iodine. The aim of our study was to evaluate the impact of [(18)F]FDG-PET/CT in both the assessment of overall extent of the disease and the therapeutic management in a group of stage-IV DTC patients
Does China plan and evaluate foreign aid projects like traditional donors
No full textThe original publication is available at http://www.sun.ac.za/ccsThis Discussion Paper focuses on a relatively less analysed question regarding the Chinese foreign aid system. Firstly I examine the basic features of the planning and evaluation system of the Development Assistance Committee members of the Organisation for Economic Cooperation and Development. This study is useful as it provides a basis for comparison in order to be able to explore the methodologies and features pertaining to the planning and evaluation systems of the Chinese. I start this exploration path by analysing the principles that form the foundation of Chinese foreign aid and compare them with those of traditional donors. This comparison gives us an idea of the strong cultural, political and economical differences that exist between the traditional donors and China. Moreover I define the identity of the two main aid channels, and survey the main planning and assessing features connected to them. For both aid channels I analyse the design and evaluation system separately, observing the presence or lack of information about actors, methodologies, features and criteria. To better present the results of this research, and to make easier comparisons of similarities and differences, the results disclosure is made, where possible, through illustrative graphs and explicative tables.Publishers' versio
Grand canonical Monte Carlo simulations of the hydrogen and methane storage capacities of novel but MOFs at room temperature
No full textProducción CientíficaHydrogen Fuel Cell Electric Vehicles (HFCEVs) and Natural Gas Vehicles (NGVs) are cleaner alternatives to present oil-based vehicles. The main problem of these technologies is the on-board storage. Metal-organic frameworks (MOFs) is one of the main groups of solid porous materials that can be used to store hydrogen or methane on-board these vehicles at room temperature and low or moderate pressures. The synthesis of these materials is usually expensive. Recently a group of eleven new BUT MOFs (BUT: Beijing University of Technology) has been synthesized using cheap organic precursors. Grand Canonical Monte Carlo simulations (GCMC) of the hydrogen and methane storage capacities and isosteric heats of these BUTs have been carried out and analyzed at 298.15 K and at pressures in the range 0.5–50 MPa. The correlations between the storage capacities and the porosity, the density, the pore size and the isosteric heat of the MOFs are analyzed. According to the simulations, three of the newly developed BUTs demonstrated high storage capacities for both hydrogen and methane. BUT-104 and 105 exhibited useable hydrogen volumetric and gravimetric capacities of approximately 0.023–0.027 kg/L and 4 wt % at 50 MPa. Additionally, they showcased useable methane volumetric and gravimetric capacities of 0.16–0.21 kg/L and 25 wt % at 25–35 MPa. Moreover, BUT-107 achieved the U.S. Department of Energy (DOE) hydrogen target for 2025, with a useable hydrogen gravimetric capacity of 5.5 wt % at 27 MPa. Furthermore, BUT-107 met the corresponding DOE methane targets, with useable methane volumetric and gravimetric capacities of 0.25 kg/L and 33.33 wt % at 50 MPa.Ministerio de Ciencia e Innovación y Ministerio de Universidades (Beca PGC2018-093745-B-I00)Junta de Castilla y León (Beca VA124G18
Modelling physical characteristics of river habitats
No full textThe physical characteristics of river habitats constitute the setting in which fluvial biota dwell and thrive. Determining the spatial and temporal patterns of physical habitat characteristics and the main factors that control them is extremely important to increase the efficiency of river management, conservation, and restoration. This study determined spatial patterns of physical habitat characteristics for Atlantic and Mediterranean rivers in northern Spain and developed a river classification based on hydromorphological characteristics. Data gathered from almost 600 sites following a modified version of the River Habitat Survey methodology were used. In addition to the usual River Habitat Survey variables, the sequence of hydromorphologic units (i.e., areas exhibiting similar hydraulic characteristics, in terms of water velocity and depth), water depths, and widths were recorded. Unmodified reaches were selected computing the Habitat Modification Score. Multiple Linear Regression models were employed to test relationships between Principal Component Analyses that summarized physical river habitat characteristics with ecological relevance and environmental variables (i.e., climate, topography, land cover, and geology) at different spatial scales and used to predict physical habitat attributes for all river reaches. The density of hydromorphologic units, flow turbulence, substrate size, and channel dimensions were able to discriminate river classes within the river network, with topography being the main environmental driver of habitat characteristics (although climate, geology, and land cover were also relevant). This classification scheme could constitute a useful tool to restore physical habitat conditions in modified river reaches.info:eu-repo/semantics/acceptedVersio
Development of a PWM based transmitter for P-band SAR applications
No full textIn this paper, authors present the preliminary measurements of a PWM-based transmitter. It is realised by cascading a pulse width modulator and a driver stage (PWCD), with a high efficiency Class E switched mode power amplifier (SMPA). The PWCD was realized by using 250nm BiCMOS process from IHP (SGB25V GD), while the SMPA was realized by using a packaged GaN device from UMS (CHK040A-SOA). The preliminary results showed output power levels higher than 40W with efficiency close to 70 %
Assumpció Estivill i Rius, L'Escola de Bibliotecàries. 1915-1939. Barcelona, Diputació de Barcelona arnb la col.laboració de la Universitat de Barcelona, 1992. 508 ps.
No full textNo costa gaire de constatar que, dins l'àmbit de la historiografia catalana, n'és la vessant més desatesa la de la història de les institucions. Per a explicar-nos una tal precarietat, cabria especular potser amb la instintiva reacció de rebuig dels catalans a heure-se- les, fins i tot en el plano1 purament teòric i retrospectiu, amb uns organismes d'ordenació social esdevinguts majoritàriament aliens i hostils a partir de la data infausta del 1714. Però aquesta suposició no bastaria ni de molt a donar raó del fet que una tal negligència hagi afectat també l'estudi d'institucions inequívocament catalanes i, doncs, sovint creades per gent del país ben al marge de les directament vinculades al poder d'estat
Design and test of a pulse-width modulator and driver for space-borne GaN switch mode power amplifiers in P-band
No full textIn this paper, the design and test of a single-chip RF pulse-width modulator and driver (PWMD) aimed at exciting a high-power class-E GaN high-power stage at 435 MHz is described. For the required buffer size, avoiding potential ringing of the pulses within the buffer structure presents a major challenge in the design process. Therefore, a smaller test chip capable of driving capacitive loads of up to 5 pF was initially designed, fabricated, and tested. An approach based on three-dimensional electromagnetic simulations was used to validate the test results and offers excellent simulation accuracy. Based on the results obtained for test chip an enlarged PWMD chip capable of driving a 40 W high-power stage has been designed and tested on passive loads representing the targeted final stage
PET/CT imaging in neuroblastoma.
No full text123Iodine-metaiodobenzylguanidine (123I-MIBG) scintigraphy is currently the tracer of choice for neuroblastoma (NB). It has high diagnostic accuracy and prognostic value for the assessment of patients after chemotherapy. A positive 123I-MIBG scan is also used for the basis of targeted radionuclide therapy with 131I-MIBG. I-123 MIBG scan however has some limitations which should be taken into account. Moreover the reasons for false negative MIBG results have not been entirely elucidated. Meticulous correlation with radiological examinations and recognition of the normal distribution pattern of 123I-MIBG in children is vital to obtain optimal results. With its technical superiorities, positron emission tomography/computed tomography (PET/CT) can be successfully introduced into the diagnostic workup of NB. Different PET tracers have been offered for imaging in patients with NB, and the efficacy of this modality has been compared with that of 123I-MIBG scan. Our review aims to analyze the present role of PET/CT imaging and radiopharmaceuticals in NB
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