Idees per estalviar aigua

Idees per estalviar aigu

Una d'escarabats

Una d'escarabat

Comprenent els forats negres

Comprenent els forats negre

(Re)Considerant els neandertals

(Re)Considerant els neandertal

Desertificació i canvi climàtic

Desertificació i canvi climàti

Distance-Based Methods: Ripley’s K function vs. K density function

In this paper, we propose an analytical and methodological comparison between two of the most known distance-based methods in the evaluation of the geographic concentration of economic activity. These two methods are Ripley’s K function, a cumulative function popularised by Marcon and Puech (2003) that counts the average number of neighbours of each point within a circle of a given radius, and K density function, a probability density function of point-pair distances introduced by Duranton and Overman (2005), which considers the distribution of distances between pairs of points. To carry out this comparison, we first apply both methodologies to an exhaustive database containing Spanish manufacturing establishments and we evaluate the spatial location patterns obtained from both analysis. After an initial analysis, we realise that although these functions have always been treated as substitutes they should be considered as complementary, as both cumulative function and probability density function provide relevant and necessary information about the distribution of activity in space. Therefore, our next step will be to assess what are the advantages and disadvantages of each methodology from a descriptive and analytical way.

Thought Control Questionnaire (TCQ): psychometric properties of the Portuguese (Portugal) version

The Thought Control Questionnaire (TCQ) assesses the strategies to control intrusive thoughts. In the present study we evaluated the factorial structure using confirmatory factor analysis (CFA) to analyze its reliability. We also analyzed the convergent and divergent validity. A sample of 558 participants from the Portuguese community replied the TCQ, the Revised Intrusions Inventory, the White Bear Suppression Inventory, the Penn State Worry Questionnaire and the Maudsley Obsessive-Compulsive Inventory. The CFA showed that the original five-factor model (Wells and Davies, 1994) produced an acceptable fit. However, fifteen items obtained factor loadings less than .40, whereby its reformulation would be advisable. The TCQ provided adequate levels of reliability and validity

Capas finas de ZrO2 para mejorar la resistencia química de los vidriados mates de calcio

La resistencia al ataque químico de vidriados cerámicos susceptibles al mismo, concretamente formulados a partir de una frita mate de calcio, se ha mejorado depositando en la superficie una capa delgada de óxido de circonio. Un sol de circonio estabilizado es el precursor de la capa, el cual se deposita mediante aerografía sobre el vidriado cocido y con un tratamiento térmico suave (Tmax ≈ 400 ºC), es transformado en ZrO2 y anclado a la superficie. Los ensayos de resistencia química demuestran que el vidriado protegido no sufre un ataque apreciable visualmente por parte del ácido clorhídrico concentrado, condiciones en las que el mismo vidriado sin el recubrimiento resulta gravemente dañado. El precursor utilizado genera una capa de óxido de circonio que protege el vidriado subyacente, de modo que el ataque químico por parte del ácido clorhídrico queda confinado al entorno de las grietas y discontinuidades de la capa depositadaPeer reviewe

SiC JFET/P-MOSFET cascode for SSCB and inrush current limiter in 300V DC power systems

This work presents a solid-state distribution and protection switch based on the SiC JFET/P-MOSFET cascode structure. The concept is aimed for 300V applications, but it can be adapted easily to other voltages. Detailed circuit design and simulation is discussed, as well as the potential application in 300V bus voltage satellite

A stable anthraquinone-derivative cathode to develop sodium metal batteries: the role of ammoniates as electrolytes

Rechargeable sodium metal batteries constitute a cost-effective option for energy storage although sodium shows some drawbacks in terms of reactivity with organic solvents and dendritic growth. Here we demonstrate that an organic dye, indanthrone blue, behaves as an efficient cathode material for the development of secondary sodium metal batteries when combined with novel inorganic electrolytes. These electrolytes are ammonia solvates, known as liquid ammoniates, which can be formulated as NaI·3.3NH3 and NaBF4·2.5NH3. They impart excellent stability to sodium metal, and they favor sodium non-dendritic growth linked to their exceedingly high sodium ion concentration. This advantage is complemented by a high specific conductivity. The battery described here can last hundreds of cycles at 10 C while keeping a Coulombic efficiency of 99% from the first cycle. Because of the high capacity of the cathode and the superior physicochemical properties of the electrolytes, the battery can reach a specific energy value as high as 210 Wh kg−1IB, and a high specific power of 2.2 kW kg−1IB, even at below room temperature (4 °C). Importantly, the battery is based on abundant and cost-effective materials, bearing promise for its application in large-scale energy storage.This work has been developed in the context of project RTI2018–102061–B–I00 financed by FEDER/Ministerio de Ciencia e Innovación-Agencia Estatal de Investigación. The Generalitat Valenciana through project PROMETEO/2020/089 is also gratefully acknowledged