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Search Results: 1 - 10 of 344751 matches for " Carlos J. "
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Using Neural Networks for Simulating and Predicting Core-End Temperatures in Electrical Generators: Power Uprate Application  [PDF]
Carlos J. Gavilán Moreno
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.31001
Abstract: Power uprates pose a threat to electrical generators due to possible parasite effects that can develop potential failure sources with catastrophic consequences in most cases. In that sense, it is important to pay close attention to overheating, which results from excessive system losses and cooling system inefficiency. The end region of a stator is the most sensitive part to overheating. The calculation of magnetic fields, the evaluation of eddy-current losses and the determination of loss-derived temperature increases, are challenging problems requiring the use of simulation methods. The most usual methodology is the finite element method, or linear regression. In order to address this methodology, a calculation method was developed to determine temperature increases in the last stator package. The mathematical model developed was based on an artificial intelligence technique, more specifically neural networks. The model was successfully applied to estimate temperatures associated to 108% power and used to extrapolate temperature values for a power uprate to 113.48%. This last scenario was also useful to test extrapolation accuracy. The method is applied to determine core-end temperature when power is uprated to 117.78%. At that point, the temperature value will be compared to with the values obtained using finite elements method and multivariate regression.
Quantitative Modeling of Currents from a Voltage Gated Ion Channel Undergoing Fast Inactivation
Carlos J. Camacho
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0003342
Abstract: Ion channels play a central role in setting gradients of ion concentration and electrostatic potentials, which in turn regulate sensory systems and other functions. Based on the structure of the open configuration of the Kv1.2 channel and the suggestion that the two ends of the N-terminal inactivating peptide form a bivalent complex that simultaneously blocks the channel pore and binds to the cytoplasmic T1 domain, we propose a six state kinetic model that for the first time reproduces the kinetics of recovery of the Drosophila Shaker over the full range of time scales and hyperpolarization potentials, including tail currents. The model is motivated by a normal mode analysis of the inactivated channel that suggests that a displacement consistent with models of the closed state propagates to the T1 domain via the S1-T1 linker. This motion stretches the bound (inactivating) peptide, hastening the unblocking of the pore. This pulling force is incorporated into the rates of the open to blocked states, capturing the fast recovery phase of the current for repolarization events shorter than 1 ms. If the membrane potential is hyperpolarized, essential dynamics further suggests that the T1 domain returns to a configuration where the peptide is unstretched and the S1-T1 linker is extended. Coupling this novel hyperpolarized substate to the closed, open and blocked pore states is enough to quantitatively estimate the number of open channels as a function of time and membrane potential. A straightforward prediction of the model is that a slow ramping of the potential leads to very small currents.
The graph bisection minimization problem
Luz,Carlos J.;
Investiga??o Operacional , 2003,
Abstract: a method of determining a lower bound for the graph bisection minimization problem is described. the bound is valid for weigthed graphs with edge and node weights. the approach is based on lagrangian relaxation and was previously used for determining an upper bound on the independence number of a graph. the determination of the lower bound is done by solving a quadratic programming problem. a characterization of the solutions of this problem is proved which allows to approximate the optimal solution of the graph bisection minimization problem. some computational experiments are reported.
El miedo al crimen en México: Estructura lógica, bases empíricas y recomendaciones iniciales de política pública
Vilalta Perdomo, Carlos J.;
Gestión y política pública , 2010,
Abstract: a logical structure and the empirical bases for the study of fear of crime are proposed. a theoretical framework is tested via ordinal regression model on the results of the fourth survey onvictimization and institutional efficacy (envei) of 2006. the main finding is that fear of crime at the neighborhood level is dependent upon the experience of being a crime victim, the levels of trust in local police and the content of the media news. these findings are partially different from previous studies in other countries. a discussion of the results, some ideas for further research and public security policy recommendations are included.
Alternativas, responsabilidad y respuesta a razones
Ideas y Valores , 2009,
Abstract: this paper is intended to defend the principle of alternative possibilities (ppa) against two recent putative counterexamples to it, inspired by the one that harry frankfurt designed forty years ago. the first three sections provide a summary of the state of the art. in the remaining sections, the counterexamples to pap of widerker's (?brain-malfunction-w?) and pereboom's (?tax evasion?) are successively presented and discussed. we hold that both examples breach at least one of two conditions that are required in order to refute pap, namely, (1) that the agent is morally responsible for his/her decision and (2) that s/he lacks any morally significant (?robust?) alternatives to it. regarding (1), the examples face several problems concerning the ?reasons-responsiveness? of the agent's mechanism of deliberation and decision making, which throws doubts upon his/her moral responsibility. regarding (2), we try to show that the respective agents have robust alternatives within their reach. we conclude, then, that pap is not refuted by these examples.
O histórico de caso e a insuficiência da trama
Escars, Carlos J.;
ágora: Estudos em Teoria Psicanalítica , 2002, DOI: 10.1590/S1516-14982002000100003
Abstract: starting from the question on the relation between the transmission of psychoanalysis and the structure of case histories two views on the nature of case histories are presented. one maintains that these texts must point to the transparent transmission of the facts that arise during the analysis, and the other emphasizes its narrative dimension as a report, with a plot which would provide coherence. this paper propounds that for psychoanalysis the plot is always inaccurate, and refers to the freudian ways of making it evident: the emphasis on the fragmentary and a peculiar way of enunciation. the paper ends with a question about the strategies which every analyst must pursue to include in the narrative of cases what is irreducible to it.
Chain control sets and fiber bundles
Barros, Carlos J. Braga;
Computational & Applied Mathematics , 2003,
Abstract: let s be a semigroup of homeomorphisms of a compact metric space m and suppose that is a family of subsets of s. this paper gives a characterization of the -chain control sets as intersection of control sets for the semigroups generated by the neighborhoods of the subsets in . we also study the behavior of -chain control sets on principal bundles and their associated bundles.
Más allá de los 240*
Novoa M,Carlos J;
Revista Colombiana de Psiquiatría , 2008,
Abstract: anorexia nervosa (an) has an etiology where there are different factors, one of them relevant: taking some female corporal figure like the absolute of woman’s existence. this false stereotype pushes many women to absurd diets without any medical control, which causes an. to change the dominant consumer society which alienates us, it is without doubt one of the best preventive therapies against an.
El costo social de la incertidumbre macroeconómica. Venezuela, 1968-2004. Una perspectiva
Carlos J. Pe?a
Perfil de Coyuntura Económica , 2007,
Abstract: la incertidumbre macroeconómica tiene efectos negativos sobre el desempe o económico. Especialmente, las decisiones de inversión se ven afectadas, implicando esto una postergación en dicha inversión y una reducción importante de la misma. Sin embargo, esta situación acarrea otros costos, como son los sociales. Así, un incremento en la incertidumbre genera una pérdida de bienestar, que está asociada a la caída de la inversión privada y la volatilidad del crecimiento económico. Este trabajo tiene como propósito aproximarse al estudio de la pérdida de bienestar que el incremento en la incertidumbre macroeconómica generó para Venezuela en el lapso 1968-2004. Para ello, se construyó un índice de incertidumbre macroeconómica, utilizando un conjunto de variables, entre las cuales están: inflación, tipo de cambio real, tasa de interés real, términos de intercambio, déficit/superávit fiscal primario no petrolero y la liquidez monetaria.
Choques petroleros, incertidumbre e inversión privada. Venezuela, 1968-2007
Carlos J. Pe?a
Perfil de Coyuntura Económica , 2008,
Abstract: Venezuela es una economía peque a y abierta, en consecuencia los shocks externos tienen una significativa importancia en su evolución, dinamismo y comportamiento. En particular, los shocks sobre los términos de intercambio, juegan un papel determinante en la explicación del comportamiento del crecimiento económico. En este trabajo se presenta la dinámica de la inversión privada en Venezuela ante los choques petroleros. La inversión es afectada por los niveles de incertidumbre macroeconómica, lo que genera reducciones importantes en la inversión privada. Pero la incertidumbre se incrementa a partir de las variaciones en los términos de intercambio y en el tipo de cambio real y éstas variables son afectadas por la volatilidad en los precios petroleros. En este contexto, el propósito del trabajo es determinar el impacto de los choques petroleros sobre la incertidumbre y la inversión privada en Venezuela para el periodo de tiempo 1968-2007, utilizando para ello la metodología de las funciones impulso respuesta, las cuales se obtienen de un modelo denominado vector de mecanismo de corrección de error (VECM).
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