Optimization of modular wiring harnesses by means of regression models for temperature prediction of wire bundles

Automotive wiring harnesses have become heavier and more complex due to their increasing number of electrical components. It is now desired to reduce their mass of copper. For this purpose, experimentation can be partially replaced by simulation, but it is still impossible to exhaustively simulate all of the combinations of modular wiring harness. This proposed approach consists of carrying out simulations using the FEM method and using their results to create regression models. Polynomial formulae can give the same information as simulations within a clearly reduced time and satisfying accuracy. An optimization algorithm introduced in this study will use them to assign new cable cross-sections of harnesses considering their currents and the ambient temperature.Postprint (author's final draft

Custom integer optimization method for wire bundle dimensioning

Automotive wiring harnesses have gained weight and complexity through the last decades due to the increasing number of electrical components, which has raised the interest on its weight optimization. For this purpose, it is essential to know at least the maximum amount of steady current that either single wires or bundles can carry. However, the large amount of combinations of the customer-speci¿c wire harnesses makes it impossible to exhaustively simulate all of the combinations that would allow for a reliable analysis and optimization of the network. The proposed approach consists of achieving accurate predictions of the wire thermal behaviour using fast on-line polynomial functions, which have been created as regression models using data from off-line worst-case ¿nite element sim- ulations. These regression models provide good accuracy for the critical dimensions of wire bundles in a much shorter time than simulations, so that they can be used on-line in optimiza- tion algorithms. Two different approaches of optimization are presented here in order to assign discrete values of available wire cross-section to the wire bundles: The ¿rst one uses integer linear programming, and the second one consists of a recently created custom algorithm whose objective is to reduce the computation time of the integer linear programming approach. This latter objective is satisfactorily accomplished. Results of both optimization approaches are validated by means of ¿nal ¿nite element simulations, and they promisingly ful¿ll the objectives of this study.Peer ReviewedPostprint (author's final draft

Vía Aérea Difícil Desconocida en pacientes obstétricas

La Vía Aérea Difícil (VAD) supone un auténtico desafío en las pacientes obstétricas no habiéndose establecido un consenso para su manejo o un algoritmo universalmente aceptado. La “causa anestésica” permanece en la lista de primeras causas de mortalidad materna, y el manejo de la vía aérea lidera esta categoría. La dificultad de intubación en estas pacientes llega a ser hasta 10 veces mayor que en la población general, por lo que la altísima morbi-mortalidad tanto materna como fetal asociada a un manejo deficiente la vía aérea desconocida en la paciente obstétrica exige más atención

Determinantes de la relación entre el precio y el valor contable de las acciones

La teoría financiera predice que la relación entre el precio y el valor contable de las acciones (el ratio PB) será tanto mayor cuanto mayor sean las expectativas de rentabilidad y crecimiento de los recursos propios, y cuanto menor sea la rentabilidad exigida por los accionistas. Este trabajo contrasta estas relaciones a partir de una muestra de empresas cotizadas en la Bolsa de Madrid durante el período 1986-2000. Nuestros resultados confirman la existencia de una relación positiva entre los valores contemporáneos del ratio PB y la rentabilidad financiera de las empresas. Al mismo tiempo, la rentabilidad financiera muestra una elevada persistencia, que se traduce en una relación positiva entre el ratio PB actual y las rentabilidades financieras futuras. Sin embargo, las rentabilidades observadas en cada año permiten predecir las rentabilidades a corto plazo mejor que el propio ratio PB, mientras que a muy largo plazo el ratio PB es una variable predictiva mejor de las rentabilidades. Por último, también constatamos una relación positiva del ratio PB con el crecimiento futuro de los recursos propios, y negativa con respecto al riesgo medido por el coeficiente B del modelo de mercado.In a efficient market, financial theory predicts that price-to-book (PB) ratios should depend on expected future return on equity (ROE), the related growth in book value of equity, and the required rate of return. This paper presents the results of an empirical analysis of those relations using a sample of firms listed in the Madrid stock exchange during the period 1986–2000. The evidence presented here is consistent with the results of previous studies in that it suggests that current PB and ROE are positively correlated. Additionally, the persistence in ROE drives a positive relationship between the PB ratio and the future ROEs, and current PB ratio have explanatory power for future ROEs in the long term beyond current ROE. Finally, we found a positive relationship between the PB ratio and the future growth in book values, and a negative relationship between the PB ratio and the risk when it is measured using the β coefficient of the market model

Relaciones interindustriales y difusión de la innovación: una aproximación desde la Teoría de Redes

El análisis input-output es una herramienta de gran potencialidad que permite profundizar en el conocimiento de la estructura productiva de un espacio económico. Por otro lado, el entramado sectorial constituye uno de los posibles factores determinantes en la capacidad de innovación de un territorio. En este trabajo, desde la óptica de la teoría de redes, se estudian algunas características estructurales de la red productiva de la economía andaluza relevantes en la difusión de la innovación y la tecnología. En particular, se exponen y calculan diversos indicadores relacionados con el concepto topológico de centralidad.graphs theory, input output analysis, innovation

Determinantes fundamentales del ratio PER: análisis teórico y evidencia empírica

Este trabajo presenta una discusión teórica sobre los fundamentos de la utilización del ratio PER en el análisis de inversiones, así como los resultados de un análisis empírico de la persistencia del ratio, sus factores determinantes y su capacidad para explicar el crecimiento futuro de los resultados, a partir de una muestra de empresas cotizadas en la Bolsa de Madrid. La evidencia hallada indica que el ratio tiene un comportamiento persistente en el tiempo, de modo que al agrupar a las empresas en carteras, buena parte de las diferencias entre los valores correspondientes a las carteras extrremas se mantienen en el tiempo. Además, encontramos que los valores extremos del ratio están asociados a importantes reversiones en el crecimiento de los resultados, lo que sugiere que el PER es un buen indicador de la existencia de componentes transitorios en el resultado. Finalmente, el análisis de los factores determinantes del ratio puso de manifiesto que ni el coeficiente beta ni el crecimiento de los resultados observado en los ejercicios futuros permiten explicar las diferencias observadas en los valores actuales del PER. Esto puede interpretarse como una muestra de la incapacidad del mercado para predecir el comportamiento futuro de los resultados, de la incapacidad de la beta para reflejar adecuadamente el riesgo asociado a los títulos, o bien de la existencia de factores determinantes de la relación resultado-precio que nada tienen que ver con el crecimiento futuro de los resultados.This paper presents a theoretical discussion on the foundation of the use of the P/E ratio in investment analysis and presents the reasults of an empirical analysis of its persistence, fundamental determinants and explanatory ability of future earnings growth on the basis of a sample of firms listed in the Madrid Stock Exchange. We found that the P/E ratio has a high degree of time-series persistence, as when firms are grouped in protfolios, a large amount of the difference between the median values of the ratio for the extreme portfolios persists up to 10 years after formation. Our results also indicate that extreme values of the P/E ratio are asociated to signifiicant earnings, and therefore, that the ratio ias a good indicator of the existence of transitory components in earnings. Finally, the analysis if the determinants of the P/E ratio revealed that neither the CAPM beta nor subsequent observed earnings growth account for the cross-sectional differences in the values of the ratio. This may be interpreted as a proof of the market¿s lack of ability to predict future earnings from historic information, of the lack of validity of beta as a proxy for risk, or of the existence of certain determinants ot the earnings-price relationship that hace nothing to do with future earnings growth

An improved class of estimators in RR surveys

This work proposes a general class of estimators for the population total of a sensitive variable using auxiliary information. Under a general randomized response model, the optimal estimator in this class is derived. Design‐based properties of proposed estimators are obtained. A simulation study reflects the potential gains from the use of the proposed estimators instead of the customary estimators.Ministerio de Educación y CienciaConsejería de Economía, Innovación, Ciencia y Emple

RRTCS: An R Package for Randomized Response Techniques in Complex Surveys

Randomized response (RR) techniques may be used to compile more reliable data, to protect the respondent's confidentiality, and to avoid an unacceptable rate of nonresponse when the information requested is sensitive (e.g., concerning racism, drug use, abortion, delinquency, AIDS, or academic cheating). Standard RR methods are used primarily in surveys that require a binary response to a sensitive question, and seek to estimate the proportion of people presenting a given (sensitive) characteristic. Nevertheless, some studies have addressed situations in which the response to a sensitive question results in a quantitative variable. RR methods are usually developed assuming that the sample is obtained using simple random sampling. However, in practice, most surveys are complex and involve stratification, clustering, and an unequal probability of selection of the sample. Data from complex survey designs require special consideration with regard to the estimation of finite population parameters and to the corresponding variance estimation procedures, due to the reality of significant departures from the simple random sampling assumption. In such a complex survey design, unbiased variance estimation is not easy to calculate, because of clustering and the involvement of (generally complex) second-order inclusion probabilities. In view of these considerations, a new computer program has been developed to provide a method for estimating the parameters of sensitive characteristics under a variety of complex sampling designs

Regression Models in Complex Survey Sampling for Sensitive Quantitative Variables

Randomized response (RR) techniques are widely used in research involving sensitive variables, such as drugs, violence or crime, especially when a population mean or prevalence must be estimated. However, they are not generally applied to examine relationships between a sensitive variable and other characteristics. This type of technique was initially applied to qualitative variables, and studies later showed that a logistic regression may be performed with RR data. Since many of the variables considered in this context are quantitative, RR techniques were extended to these cases to estimate the values required. Regression analysis is a valuable statistical tool for exploring relationships among variables and for establishing associations between responses and covariates. In this article, we propose a design-based regression analysis for complex sample designs based on the unified RR approach. We present estimators of the regression coefficients, study their theoretical properties and consider different ways to estimate their variance. The properties of these estimation techniques were simulated using various quantitative randomized models. The method proposed was also used to analyse the findings from a real-world survey.Ministerio de Ciencia e Innovación of Spai

Patología de Cabeza y Cuello: NAP4

Debemos obtener toda la información preoperatoria posible sobre la VA. Salvo por la presencia de estridor, que deberemos considerar como señal de alarma, en el resto de los casos hay que explorar la VA de forma conjunta con el cirujano, mediante las imágenes de CT, RM o una fibroendoscopia nasal y conocer el nivel de la obstrucción (cavidad oral, base de la lengua, región supraglótica, glótica o infraglótica) de gran influencia en la eficacia de las técnicas que luego vayamos a utilizar. Para un manejo seguro de la VA es necesario establecer una estrategia, con un plan 1º, habitualmente dirigido a una meta concreta (p.ej. la intubación traqueal), y un plan 2º o de rescate dirigido a esa misma meta o a otra diferente (p.ej. oxigenación efectiva o despertar al paciente). El plan de rescate es igual o más importante que la estrategia 1ª y es fundamental no retrasar su puesta en marcha cuando es necesario