Una propiedad de las álgebras de Lie semisimples con forma de killing indefinida

The real connected Lie Groups may be or not the reunion of their uniparametric subgroups. The aim of this note is to study a characterization of the Lie Groups such that are the reunion of their uniparametric subgroups . To begin with, it is proved that if G is a real connected semisimple Lie Group and the Killing form on the Lie Algebra of G is an indefinide form, G is not the reunion of their uniparametric subgroups. It is proved the next result : "Let G be a real connected Lie Group . G is the reunion of their uniparametric subgroups if and only if rad(G) is exponential and the Killing form on the Lie Algebra of G/rad(G) is a definide form (positive or negative)

Suitability of Blackboard as Learning Management System to assess oral competence: Students’ perceptions and results

[EN] Learning a foreign language involves the practice and development of linguistic competencies through a series of communicative activities. Assessing each of these competencies face to face can provide an accurate profile of the student’s level of language proficiency. But assessing them online, particularly oral skill, poses a challenge for both students and professors. The change of scenario and use of digital tools may intimidate students and deprive the interview from naturality and warmth. In this paper, the suitability of Blackboard Collaborate as Learning Management System to assess English speaking skill is studied together with other factors influencing students’ online performance. 81 students from 5 different undergraduate programs in Engineering and Applied Sciences were assessed, following the threefold pattern of IELTS speaking test questions. Their results and responses to a final survey are contrasted so as to check the positive of negative effect of online testing on the students’ state of mind and eventual achievement. Blackboard platform proves to be as a suitable online framework for optimal performance, and the examiner’s attitude is equally a conditioning factor in students’success.Muñoz Alcón, AI.; Trullén Galve, F. (2021). Suitability of Blackboard as Learning Management System to assess oral competence: Students’ perceptions and results. En 7th International Conference on Higher Education Advances (HEAd'21). Editorial Universitat Politècnica de València. 983-991. https://doi.org/10.4995/HEAd21.2021.12929OCS98399

Social desirability bias in the environmental economic valuation: An inferred valuation approach

Environmental economic valuation allows to derive values from individuals’ behaviour in hypothetical markets, but it is not exempt from certain biases. this work aims to evidence the existence of social desirability bias (sdb) in the use of the stated preference method for environmental valuation. sdb is due to the consideration that, when interviewed, people provide responses to match the interviewer’s expectations or to be consistent with social norms. the inferred valuation approach (iva) was used to identify and quantify the social desirability bias in a choice experiment survey conducted to estimate the benefit of protecting a coastal natura 2000 site. the results revealed the existence of a sdb that increases by 2.8-fold the benefits of the valued environmental assets. it is also found greater differences between use and non-use values when the iva is used.This work was carried out under the project AGRISERVI funded by the Spanish Ministry of Science, Innovation and Universities under the European Regional Development Fund (ERDF) [AGL2015-64411-R (MINECO/FEDER, UE)], and the 20912/PI/18 project (Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia). Useful comments provided by Faustino Martínez, Ramón Ballester and Juana Guirao from OISMA are gratefully acknowledge

Analysis of the waste selective collection at drop-off systems: Case study including the income level and the seasonal variation

There are several factors which have an influence in the selective collection of the municipal waste. To define a selective collection system, the waste generation pattern should be firstly determined and these factors should be analyzed in depth. This paper tries to analyze the economic income level and the seasonal variation on the collection and the purity of light-packaging waste to determine actions to improve the waste management plan of a town. In the first stage of the work, waste samples of the light-packaging containers were collected in two zones of the town with different economic characteristics in different seasons during one year. In the second stage, the samples were characterized to analyze the composition and purity of the waste. They were firstly separated into four fractions: metals; plastic; beverage cartons; and misplaced materials. The misplaced fraction was in its turn separated into cardboard, rubber and leather, inert waste, organic matter, paper, hazardous waste, clothes and shoes, glass and others. The plastic fraction was separated into five types of plastics and the metal fraction into three. In the third stage, the data have been analyzed and conclusions have been extracted. The main result is that the quality of the light-packaging fraction collected in these zones during both seasons were similar. This methodology can be extrapolated to towns with similar characteristics. It will be useful when implementing a system to collect the waste selectively and to develop actions to achieve a good participation in the selective collection of the waste

Assessment of Irrigation Pricing Policies: A Data Envelopment Analysis Approach

The European Water Framework Directive encourages pricing policy reforms in order to protect the environmental quality of water and promote its efficient use. This paper deals with two aspects of efficiency, namely economic and environmental efficiency, analyzed for different pricing methods. Volumetric pricing methods are compared with other indirect schemes (‘per area’, on ‘input’, on ‘output’ and ‘quota’) under three different water saving scenarios. The Data Envelopment Analysis (DEA) technique is used to assess the eco-efficiency of an eventual water pricing reform in the irrigated agricultural system of Capitanata, in Italy. Overall, findings point out that a pricing system based on ‘per area’ and ‘output’ will lead to the highest eco-efficiency, although this is not valid under any water pricing charge. The enforcement of water saving via pricing does not imply a higher eco-efficiency, mainly in the case of environmental efficiency. The use of the DEA approach appears useful in the assessment of water pricing policies where conflictive economic and environmental goals arise. It provides a methodology to support policy makers in the design of water policy pricing aimed at the enhancement of efficiency, both economic and environmenta

Adoption and diffusion of irrigation technologies: Application on the agriculture of Murcia

[SPA] Las innovaciones llegan al mercado en forma de técnica, tecnología o método de gestión, contribuyendo a un uso más eficiente de los factores de producción, a la diferenciación de los productos de las entidades que las adoptan y, por consiguiente, al logro de ventajas competitivas. El beneficio potencial derivado de su generación recae sobre la sociedad una vez que han sido adoptadas, siendo la velocidad con la que son difundidas entre sus miembros un determinante del crecimiento económico. A pesar de la importancia de la adopción de innovaciones, éstas no han sido difundidas con la velocidad deseada, tal y como recoge la amplia literatura existente, aunque escasa en cuanto a tecnologías de riego se refiere. Entre los numerosos riesgos a los que se enfrentan los gestores de las empresas agrarias se encuentra la disposición y uso del agua. Este problema adquiere especial relevancia en la Región de Murcia, donde la escasez de recursos hídricos es de las más acusadas de toda Europa. Por ello, la adopción de tecnologías ahorradoras de agua es uno de los objetivos de la política de regadíos en España, cuyas directrices establecidas en el Plan Nacional de Regadíos están orientadas al uso sostenible y racional de los recursos. También es uno de los fines de la Directiva Marco de Aguas de la Unión Europea, cuyos objetivos comprenden el buen estado de las aguas, la protección del medio ambiente y la recuperación de los costes de los servicios relacionados con el agua. En este contexto, el objetivo de esta tesis es analizar la adopción y difusión de tecnologías de riego que aumentan la eficiencia del uso del agua, reducen su consumo y promueven su conservación, dentro del ámbito de actuación que abarca a las comunidades de regantes de la Región de Murcia y a los agricultores de una de las más grandes y tecnificadas de Europa, la comunidad de regantes del Campo de Cartagena. Además, se analiza la disposición a pagar por el agua de riego de los agricultores de esta comunidad. Como la literatura sobre adopción y difusión de innovaciones es amplia y variada, se ha realizado una clarificación de los conceptos y una clasificación de modelos, así como de los factores que afectan a la adopción de innovaciones, diferenciando entre: características del agricultor, factores económicos, características de la explotación, características de la innovación y factores del entorno. El trabajo empírico realizado, tras la revisión de la literatura, se centra en la adopción y difusión de las tecnologías de distribución y control que utilizan las comunidades de regantes para gestionar el agua de riego, y la tecnología de riego por goteo empleada por los agricultores. Bajo la teoría de la utilidad esperada y en un marco de análisis temporal, se han desarrollado modelos de duración que explican el proceso de adopción seguido por las comunidades de regantes de la Región de Murcia y los agricultores de la comunidad de regantes del campo de Cartagena. También se han aplicado modelos teóricos explicativos del proceso de difusión en ambas unidades de decisión y se ha empleado un método de preferencias establecidas que permite inferir la disposición a pagar por el agua de riego de los agricultores de la citada comunidad. Los resultados obtenidos demuestran que las variables que definen una mayor garantía de suministro, y una mejor organización en la gestión del agua, influyen positivamente en la adopción de tecnología de riego por las comunidades de regantes. También se confirma que el acceso a la información de la tecnología, a través de la acumulación de aquella procedente de las fuentes de comunicación interpersonales, afecta al proceso temporal de difusión. Las características de los individuos (edad, estudios, cooperativas, aversión al riesgo, preferencias y percepciones), los factores económicos de la explotación (precio del agua y tamaño empresarial), el origen del agua y su disponibilidad, influyen en la probabilidad de adoptar tecnología de riego por goteo. Además, el empleo de metodologías que consideran los aspectos temporales del carácter subyacente del proceso de aprendizaje revela la influencia que, sobre el proceso de adopción, ejercen variables no significativas con el empleo de metodologías tradicionales. Por otra parte, se observa que los agricultores que utilizan el agua subterránea en sus explotaciones presentan una mayor disposición a pagar por la procedente de la comunidad de regantes, respecto a los que no la utilizan, así como los que están al frente de explotaciones de mayor superficie, existiendo una gran variabilidad en esta disposición y una elevada aversión al riesgo asociada al precio del agua.%&/Estos resultados son de gran utilidad para las Administraciones Públicas y las comunidades de regantes en el establecimiento de políticas agrarias, y la toma de decisiones dirigidas a un mejor aprovechamiento de los recursos hídricos y la reducción de externalidades ambientales.[ENG] Innovations reach the market as techniques, technologies or management methods, contributing to a more effective use of productive factors. They help differentiate the products of companies that adopt these innovations, with resulting competitive advantages. Once they have been adopted, the benefits derived from innovations are reflected in society, as fast as they are spread among its members. Farmers face a great deal of risks; among those is water availability and price. This problem is especially relevant in the Region of Murcia, where the scarcity of water resources is the most highly noted in Europe. This is why the adoption of water saving technology is one of the goals of the Spanish irrigation policy and the European Union Water Framework. In this context, the aim of this thesis is to analyse the adoption and diffusion of irrigation technology that increases the effectiveness of water use, and reduces its consumption within the scope of irrigation communities and farmers. Furthermore, the farmers’ willingness to pay for irrigation water is analyzed. To achieve these aims, the empirical work carried out focuses on the adoption and diffusion in two levels: irrigation communities, which adopt distributing and controlling technology and grower, who adopt drip irrigation technology. Duration models, diffusion models, and established preferences were analysed in a temporary analysis framework. The results obtained show that the variables that define a greater guarantee of provision, better organization in water management, access to information and its quality, positively influence the adoption of irrigation technologies. Individuals’ features (age, education, cooperatives, aversion to risk, preferences and perceptions), economical factors of the farm (water price and farm size), and origin of the water and its availability influence the probability of adopting drip irrigation technology. On the other hand, those farmers who use underground water in their farms are more willing to pay for the water from the irrigation community, and so are those with bigger acreages. Thus, a great variability exists in this willingness, and a high aversion to the risk is also associated with the water price.Universidad Politécnica de CartagenaPrograma de doctorado en Gestión de Empresa

The economic value of flood risk regulation by agroecosystems at semiarid areas

Agroecosystems are anthropized ecosystems that provide food and other benefits to society known as ecosystem services (ES). Among these services is the Ecosystem Service for Flood Regulation (ESFR). This regulation service has been scarcely studied in the scientific literature, which has mainly focused on factors such as land use patterns and intermediate indicators. This implies that key physical aspects that condition the development of floods and their impact on society have been ignored. The aim of this work is to develop a methodological proposal for accurate economic valuation of the ESFR provided by agroecosystems. To this end, the avoided damage method is used, carrying out hydrological and two-dimensional hydraulic modeling combined with cadastral cartography and a depth-damage function. The model thus constructed allows the quantification of the damage reduction associated with different levels of agroecosystem ESFR provision. The urban settlement composed mainly of the municipality of Los Alcázares, and also the Bahia Bella housing estate, from the municipality of Cartagena (Murcia, south-eastern Spain), is used as a case study, as it is located downstream of a predominantly agricultural area recurrently affected by floods. The results show that the value of the ESFR provided by the service-maximizing agroecosystem in the area, citrus crops, is 22.51 € ha-1 year-1 in the case study area, which is comparable with that of natural ecosystems. Furthermore, relationships were established between intermediate indicators and economic losses which, in addition to facilitating the valuation process, show a limit in the flood regulation provisioning of agroecosystems in the face of the most extreme events. This work shows the magnitude of the ESFR that can be provided by agriculture and enables its valuation in areas with similar characteristics. The information obtained can be incorporated into the decision-making process of land and risk management organizations, enabling them to rationalize agricultural spatial planning.This work was supported by the Spanish Ministry of Science and Education: AgriCambio project (Grant PID2020-114576RB-I00 funded by MCIN/AEI/ 10.13039/501100011033). Víctor Martínez-García acknowledge the financial support from the Spanish Ministry of Education and Personal Training (FPU19/05143)

Review. The evolution of research regarding the economics of irrigation water

This work analyses the main research trends (subjects, methodology used, countries of the authors and data) in the economics of irrigation water during the last 10 years (2000-2009). For this purpose, a quantitative methodology has been used which is new to this sphere, based on the review of a representative sample of 332 papers published in the 15 most important journals focused on this field of science indexed in the databases of the Institute for Scientific Information (ISI), the Science Citation Index (SCI) and the Social Science Citation Index (SCCI). The results obtained confirm: a) the notable growth in the number of papers published, especially in the last three years, b) the high degree of collaboration between authors, including those of different origin, for their performance c) the prominence of the USA, Australia, India and Spain as the countries of the first authors and origin of the data, d) the greater attention given to subjects related with «investment project analysis», «production planning» and, especially, «production function and productivity of water», and e) the predominance of empirical studies that use basic analysis approaches (cost analysis, investment evaluation, etc.).El presente trabajo analiza las principales tendencias de investigación (temáticas, metodologías utilizadas, países de los autores y de los datos) en economía del agua de riego en los últimos 10 años (2000-2009). Para ello, se ha utilizado una metodología cuantitativa, novedosa en este ámbito, basada en la revisión de una muestra representativa de 332 artículos publicados en las 15 revistas más importantes en este ámbito científico, indexadas en las bases de datos del Institute for Scientific Information (ISI), el Science Citation Index (SCI) y el Social Science Citation Index (SCCI). Los resultados obtenidos confirman: a) el notable crecimiento del número de artículos publicados, sobre todo, en los tres últimos años, b) la elevada colaboración entre los autores para su realización, incluso de diferente procedencia, c) el protagonismo de EEUU, Australia, India y España como países de los primeros autores y de procedencia de los datos, d) la mayor atención prestada a los temas relacionados con el «análisis de proyectos de inversión», la «planificación de la producción» y, especialmente, a las «funciones de producción y la productividad del agua», y e) el predominio de los trabajos empíricos que utilizan técnicas de análisis básicas (análisis de costes, evaluación de inversiones, etc.)

Multiple Sensor Monitoring of CFRP Drilling to Define Cutting Parameters Sensitivity on Surface Roughness, Cylindricity and Diameter

Machining parameters affects the final quality of components made in carbon fiber reinforced plastic (CFRP) composite materials. In this framework, the work here presented aims at studying the right combination of cutting speed (v(c)) and feed rate (v(f)), for dry drilling of carbon fiber reinforced plastic composite materials, which obtained better results regarding roughness, hole cylindricity, and diameter. A series of experimental tests were carried out under different drilling conditions (v(c)/v(f)), monitoring the thrust force (Fz), torque (T), and electric power (EP), to define which one can help more for industrial daily life production. Results validation was carried out using the analysis of variance, in order to relate main machining parameters cutting speed and linear feed, with thrust force, drilling torque, main spindle electric power and hole quality parameters (average roughness, cylindricity and diameter). The conclusions show that thrust force is not proportional to the cutting speed and the best combinations of cutting speed and feed were found out around the average values of tested parameters. Spindle electric power is an interesting element to take into account because it is easy to consider in real production