3,557 research outputs found
Investigation of electrical noise in selenium-immersed thermistor bolometers
The selenium immersed, thermistor bolometer, IR detector failed due to spurious and escalating electrical noise outburst as a function of time at elevated temperatures during routine ground based testing in a space simulated environment. Spectrographic analysis of failed bolometers revealed selenium pure zones in the insulating selenium arsenic (Se-As) glass film which surrounds the active sintered Mn, Ni, Co oxide flake. The selenium pure film was identified as a potentially serious failure mechanism. Significant changes were instituted in the manufacturing techniques along with more stringent process controls which eliminated the selenium pure film and successfully produced 22study bolometers
Towards a Semantic Gas Source Localization under Uncertainty
Towards a Semantic Gas Source Localization under Uncertainty.Communications in Computer and Information Science book series (CCIS, volume 855), doi:10.1007/978-3-319-91479-4_42This work addresses the problem of efficiently and coherently
locating a gas source in a domestic environment with a mobile
robot, meaning efficiently the coverage of the shortest distance as possible
and coherently the consideration of different gas sources explaining
the gas presence. The main contribution is the exploitation, for the
first time, of semantic relationships between the gases detected and the
objects present in the environment to face this challenging issue. Our
proposal also takes into account both the uncertainty inherent in the
gas classification and object recognition processes. These uncertainties
are combined through a probabilistic Bayesian framework to provide a
priority-ordered list of (previously observed) objects to check. Moreover
the proximity of the different candidates to the current robot location
is also considered by a cost function, which output is used for planning
the robot inspection path. We have conducted an initial demonstration
of the suitability of our gas source localization approach by simulating
this task within domestic environments for a variable number of objects,
and comparing it with an greedy approach.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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PPAR gamma pro12Ala polymorphism and type 2 diabetes: a study in a spanish cohort
Type 2 diabetes (T2D) is a disease whose occurrence is increasing prevalent in westernized civilizations and is responsible for the proliferation in the morbidity and total mortality of patients with cardiovascular diseases, worldwide. However, the complexity in the treatment and prevention of T2D arises from the intricacy of the many physical and biological factors involved in its etiology. Impaired pathways for insulin signaling have been implicated as one the many factors in the development of T2D Individual peroxisome proliferator-activated receptors (PPARs) have previously exhibited associations with alterations of lipid profiles, fat tissue and T2D and displayed complications derived from high levels of glucose. However, PPARgamma has not yet been associated with the development or developmental pathways of T2D. We performed an observational study a Spanish cohort in order to better understand the association between the SNP PPARgamma polymorphism Pro12Ala in our patients and the incidence of T2D and other cardiovascular complications. We study did not find a statistically significant relationship between the Pro12Ala and T2D development in our cohort, future observations will help us to know the association with vascular disease in patients with T2D
Plan prospectivo estrátegico 2012 de Napa -NTS : una visión prospectiva de la empresa NAPA NTS frente al TLC.
Tesis (Magíster en Administración de Empresas) -- Universidad del Norte. Programa de Maestría en Administración de Empresas, 2008.Teniendo en cuenta la permanente apertura de fronteras comerciales que se viene dando desde la década pasada, que ha llevado a la globalización de la economía, así como la gran dependencia de la empresa NAPA-NTS, de las relaciones comerciales binacionales entre Colombia Estados Unidos de América, por tener esta empresa el 85% de sus proveedores de repuestos originarios de ese país, se ha hecho necesario el análisis de los factores expuestos a cambios en la ecuación de negocios de NAPA-NTS, con la firma del tratado de libre comercio entre los dos países, mediante la realización de una prospectiva estratégica al año 2012. El objetivo principal de este trabajo es proponer un plan prospectivo para NAPA-NTS para el año 2012, mediante la metodología teórica para la construcción de prospectivas estratégicas y la utilización de los softwares MICMAC y MACTOR. El resultado obtenido en el proyecto fue el plan prospectivo de NAPA-NTS para el año 2012 con la suscripción del TLC entre Colombia y Estados Unidos de América, en el cual se consiguió la identificación de las variables claves del cambio, la descripción del eje estratégico de las variables claves del cambio, el Señalamiento de escenarios posibles prospectivos que puedan ser utilizados como la base del plan estratégico y la determinación de los actores claves que pueden generar un cambio en el nuevo ambiente de negocios de NAPA NTS con el TLC. Como conclusión del trabajo realizado, se determina la implementación de una estrategia de diferenciación, sobre la base de un producto de alta calidad apoyado sobre una cadena de distribución fortalecida y con territorios muy bien definidos y una estrategia de penetración del mercado consistente en incrementar la participación de la empresa con sus características de distribución comercial en los mercados en los que opera y con los productos actuales, es decir, en el desarrollo del negocio básico
Analysis of conventionally controlled PEMFC based on a distributed parameter model
Presentado al IV Iberian Symposium on Hydrogen, Fuel Cells and Advanced Batteries celebrado en Estoril (Portugal) del 26 al 28 de junio de 2013.The proton exchange membrane fuel cells (PEMFC) have been incorporated to a wide range of portable, stationary and automotive applications. However, PEMFC are still not accepted as a practical power generator. The key challenge is to reduce the cost and achieve a high performance and long life of the cells. Variations in the concentrations of reactants, as well as temperature, have significant effects on the performance and durability of PEMFC. All these variables exhibit spatial dependence along the channel, which needs to be taken into account in order to progress towards a PEMFC operation that is efficient and mitigates degradation. To this end, a controlled PEM fuel cell study is done through a distributed parameter simulation model. A conventional stoichiometry control objective is considered in order to analyze the behavior of spatial profiles of some important variables and, therefore, point out the importance of considering distributed parameter models in control design.Peer Reviewe
Modelling microbial exchanges between forms of soil nitrogen in contrasting ecosystems
Although nitrogen (N) is often combined with carbon (C) in organic
molecules, C passes from the air to the soil through plant photosynthesis,
whereas N passes from the soil to plants through a chain of microbial
conversions. However, dynamic models do not fully consider the
microorganisms at the centre of exchange processes between organic and
mineral forms of N. This study monitored the transfer of <sup>14</sup>C and
<sup>15</sup>N between plant materials, microorganisms, humified compartments, and
inorganic forms in six very different ecosystems along an altitudinal
transect. The microbial conversions of the <sup>15</sup>N forms appear to be
strongly linked to the previously modelled C cycle, and the same equations
and parameters can be used to model both C and N cycles. The only
difference is in the modelling of the flows between microbial and inorganic
forms. The processes of mineralization and immobilization of N appear to be
regulated by a two-way microbial exchange depending on the C : N ratios of
microorganisms and available substrates. The MOMOS (Modelling of Organic Matter of Soils) model has already been
validated for the C cycle and also appears to be valid for the prediction of
microbial transformations of N forms. This study shows that the hypothesis
of microbial homeostasis can give robust predictions at global scale.
However, the microbial populations did not appear to always be independent
of the external constraints. At some altitudes their C : N ratio could be
better modelled as decreasing during incubation and increasing with
increasing C storage in cold conditions. The ratio of potentially
mineralizable-<sup>15</sup>N/inorganic-<sup>15</sup>N and the <sup>15</sup>N stock in the
plant debris and the microorganisms was modelled as increasing with altitude,
whereas the <sup>15</sup>N storage in stable humus was modelled as decreasing with
altitude. This predicts that there is a risk that mineralization of organic
reserves in cold areas may increase global warming
Complete Coherent Control of a Quantum Dot Strongly Coupled to a Nanocavity
Strongly coupled quantum dot-cavity systems provide a non-linear
configuration of hybridized light-matter states with promising quantum-optical
applications. Here, we investigate the coherent interaction between strong
laser pulses and quantum dot-cavity polaritons. Resonant excitation of
polaritonic states and their interaction with phonons allow us to observe
coherent Rabi oscillations and Ramsey fringes. Furthermore, we demonstrate
complete coherent control of a quantum dot-photonic crystal cavity based
quantum-bit. By controlling the excitation power and phase in a two-pulse
excitation scheme we achieve access to the full Bloch sphere. Quantum-optical
simulations are in good agreement with our experiments and provide insight into
the decoherence mechanisms
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