Principal alarms in multivariate statistical process control

This paper describes a methodology for the simulation of multivariate out of control situations using in-control data. The method is based on finding the independent factors of the variability of the process, and shifting these factors one by one. These shifts are then translated in terms of the observed variables. The shifts provoked by the most important factors are called principal alarms. The principal alarms are plotted, visualizing the main deviations of the process. Also, a resampling procedure for ARL estimation using principal alarms is proposed. An application using a real industrial process, illustrates the usefulness of the methodology

Pibok-pb: A collaborative framework to improve software development productivity through projects and process assets reuse and measurement with six sigma techniques

The Software Engineering Lab (SEL-UC3M) is aimed to develop solutions to software projects processes related problems having an accessible, collaborative, practiced and manageable focus. We are interested to collaborate with research centers and universities worldwide that share our philosophy as well as with enterprises and public administrations interested in our novel methods

Large-scale analysis of Zipf's law in English texts

Despite being a paradigm of quantitative linguistics, Zipf's law for words suffers from three main problems: its formulation is ambiguous, its validity has not been tested rigorously from a statistical point of view, and it has not been confronted to a representatively large number of texts. So, we can summarize the current support of Zipf's law in texts as anecdotic. We try to solve these issues by studying three different versions of Zipf's law and fitting them to all available English texts in the Project Gutenberg database (consisting of more than 30000 texts). To do so we use state-of-the art tools in fitting and goodness-of-fit tests, carefully tailored to the peculiarities of text statistics. Remarkably, one of the three versions of Zipf's law, consisting of a pure power-law form in the complementary cumulative distribution function of word frequencies, is able to fit more than 40% of the texts in the database (at the 0.05 significance level), for the whole domain of frequencies (from 1 to the maximum value) and with only one free parameter (the exponent)

La provision voluntaria de bienes publicos: Resultados Experimentales

¿Es o no relevante la tendencia al escaqueo de los individuos que se plantean la provisión de un bien público? ¿Qué tests empíricos pueden emplearse con suficiente rigor para contrastar esta hipótesis? Como resulta difícil aislar con datos de campo la incidencia del fenómeno del polizón (free rider hypothesis), al no poder controlar las particularidades estructurales e institucionales de cada situación, se puede analizar evidencia empírica alternativa, complementaria con la anterior, generada experimentalmente. La metodología experimental crea entornos controlados simples en los que poder contrastar las hipótesis económicas y analizar su robustez ante cambios en los parámetros y en las reglas del juego. Este articulo comenta la literatura experimental que analiza mas directamente la relevancia de la hipótesis del polizón, en contextos en que la provisión del bien publico se financia exclusivamente en base a contribuciones voluntarias. Parece que en los entornos experimentales propuestos, cuando los individuos tienen la oportunidad de familiarizarse con las reglas del juego y de repetir el proceso de decisión suficiente número de veces, sí que aparece de forma persistente el fenómeno del polizón. Sin embargo, este comportamiento no es tan claro como a priori la teoria haría pensar. Se presentan algunas hipótesis que se han barajado para justificar las desviaciones observadas dentro de los canones de la racionalidad que los economistas acostumbran a imponer en sus modelos. A pesar de que estas hipótesis explican en parte estas anomalías, no parecen suficientes para reconciliar por completo la evidencia empírica con las predicciones teóricas

An Analysis of Global Research Trends on Greenhouse Technology: Towards a Sustainable Agriculture

Greenhouse farming is an agricultural management system that has demonstrated its efficiency in intensifying food production. These systems constitute a feasible alternative for ensuring food supply, which is one of the greatest challenges faced by humankind in the twenty-first century. Technology has been able to meet the challenges related to greenhouse farming in both contributing to overcoming its limitations, correcting adverse impacts and ensuring system sustainability. The objective of this article is to analyse the global research trends in greenhouse technology over the last two decades, in order to identify the main driving agents, the most outstanding research lines and possible gaps in the literature. Different methodologies have been used for the analysis; both quantitative and qualitative. The principal results show that there are different relevant lines of research related to different aspects of greenhouse farming: the use of water for irrigation, the design of the optimum structure of the greenhouse, conserving the soil in the best growing conditions, energy consumption of the system as a whole, climate control within the facility and pest control. The research is characterized by the being composed largely of ad hoc studies, which hinders the international collaboration between researchers and institutions. The research approach has shifted from being focused on increasing production and cost savings to aspects related to resource conservation and sustainability

Wild edible plants as potential antioxidant or nutritional supplements for beverages minimally processed

Wild edible plants (WEP) with high antioxidant capacity, Rosa canina fruits, Quercus ballota acorns and Sanguisorba minor (young leaves and stems), were added to orange and kiwifruit juices for increase the nutritional properties. The addition of WEP to orange juice (OJ) and kiwifruit cremogenate (KC) does not affect, or it can even improve, some parameters of consumer's acceptance, although the mixtures increasing sweetness and intensifying the matrix colour without changing the tone are the best valued. The beverages minimally processed with higher TSS were the matrices fortified with Q. ballota, the same that were considered sweetest by the judges. The addition of WEP to OJ did not significantly change the levels of vitamin C (ascorbic acid plus dehydroascorbic acid). The addition of R. canina and S. minor increased the content of phenolic compounds and antioxidant capacity in both matrices (OJ and KC) in more than 30%. Beverages with a high interest for consumers and with high antioxidant properties have been obtained