Water harvesting for young trees using Peltier modules powered by photovoltaic solar energy

Young trees transplanted from nursery into open field require a minimum amount of soil moisture to successfully root in their new location, especially in dry-climate areas. One possibility is to obtain the required water from air moisture. This can be achieved by reducing the temperature of a surface below the air dew point temperature, inducing water vapor condensation on the surface. The temperature of a surface can be reduced by applying the thermoelectric effect, with Peltier modules powered by electricity. Here, we present a system that generates electricity with a solar photovoltaic module, stores it in a battery, and finally, uses the electricity at the moment in which air humidity and temperature are optimal to maximize water condensation while minimizing energy consumption. Also, a method to reduce the evaporation of the condensed water is proposed. The objective of the system is to sustain young plants in drier periods, rather than exclusively irrigating young plants to boost their growth.

Mechanical properties of wood from Pinus sylvestris L. treated with Light Organic Solvent Preservative and with waterbone Copper Azole

El objetivo del estudio es determinar el efecto de tratamiento de la madera de Pinus sylvestris con sustancias protectoras en las propiedades mecánicas. Para ello se utilizan 40 muestras de madera libre de defectos de Pinus sylvestris L. tratándose con protectores orgánicos (Vacsol Azure WR 2601) 50 con protectores hidrosolubles (Tanalith E 3492) y 40 muestras de control sin tratamiento. Se evaluó la resistencia mecánica a la flexión estática, módulo de elasticidad y la fuerza de compresión paralela a la fibra fueron comparados con madera no tratada. El análisis de regresión entre la penetración y la fuerza de compresión paralela se realizó con las muestras tratadas con conservante a base de agua. Resultados principales: Los resultados indican que la madera tratada (con cualquiera de los productos) presenta un aumento estadísticamente significativo de la resistencia mecánica en todas las tres características mecánicas. Los resultados obtenidos difieren de estudios anteriores llevada a cabo por otros autores. No hubo correlación entre la resistencia a la compresión en paralelo y el grado de impregnación de la madera con base de agua de cobre azoles. La explicación más probable para estos resultados se refiere a cambios en la presión durante el tratamiento. El uso de muestras de control no tratadas en lugar de las muestras tratadas sólo con agua es más probable para producir resultados significativos en los estudios de resistencia mecánica . La investigación pone de relieve que la madera tratada presenta un aumento estadísticamente significativo en el Modulo de Elasticidad, módulo de rotura a la flexión estática y resistencia a la compresión paralela. No hubo correlación entre la resistencia a la compresión en paralelo y el grado de impregnación con conservante hidrosoluble.

Effect of reservoir tillage on rainwater harvesting and soil erosion control under a developed rainfall simulator.

Soil erosion is a serious environmental threat in the Mediterranean region due to torrential rainfalls, and it contributes to the degradation of agricultural land. Techniques such as rainwater harvesting may improve soil water storage and increase agricultural productivity, which could result in more effective land usage. Reservoir tillage is an effective system of harvesting rainwater, but it has not been scientifically evaluated like other tillage systems. Its suitability for the conditions in Spain has not been determined. To investigate and quantify water storage from reservoir tillage and how it could be adapted to improve infiltration of harvested rainwater, a laboratory-scale rainfall simulator was developed. Rainfall characteristics, including rainfall intensity, spatial uniformity and raindrop size, confirm that natural rainfall conditions are simulated with sufficient accuracy. The simulator was auto-controlled by a solenoid valve and three pressure nozzles were used to spray water corresponding to five rainfall intensities ranging from 36 to 112 mm h-1 for 3 to 101-year return period with uniformity coefficients between 83 and 94%. In order to assess the reservoir tillage method under surface slopes of 0, 5, and 10%, three soil scooping devices with identical volume were used to make depressions in the following forms: a) truncated square pyramid, b) triangular prism, and c) truncated cone. These depressions were compared to a control soil surface with no depression. For the loam soil used in this study, results show that reservoir tillage was able to reduce soil erosion and surface runoff and significantly increase infiltration. There was significant difference between the depressions and the control. Compared to the control, depression (a) reduced surface runoff by about 61% and the sediment yield concentration by about 79%.

Tuning the current ratio of a CPV system to maximize the energy harvesting in a particular location

A method based on experimental data is proposed to optimize the energy harvesting of a silicone-on-glass Fresnel-lens based CPV system. It takes into account the spectral variations along the year in a particular location as well as the thermal and spectral sensitivities of the optics and solar cell. In addition, different alternatives to tune the top/middle subcells current ratio in a CPV module are analyzed and their capacity to maximize the annually produced energy is quantified.

Variation throughout the tree stem in the physical-mechanical properties of the wood of Abies alba Mill. from the Spanish Pyrenees

This study analyses the variation of main physical-mechanical properties of wood along the longitudinal and radial directions of the tree for Abies alba Mill. growing in the Spanish Pyrenees. Small clear specimens were used to study the properties of volumetric shrinkage (VS), density (?), hardness (H), bending strength (MOR), modulus of elasticity (MOE), maximum compressive strength parallel to the grain (MCS) and impact strength (K). Several models of properties variation in the longitudinal and radial directions were analyzed. Main trends of variation of properties throughout the tree stem were identified although none of them could be fitted to predictive statistical models. Along the longitudinal direction, the properties studied followed a downward trend from the base to the crown, which was not significant in all cases, indicating that no differences in quality existed. Throughout the radial direction the trend is upward for the first 40-50 growth rings, after which it slopes downwards, more gently at first until rings 70-75 and then more steeply. This behaviour is related to variation in wood structure from the pith to the bark, depending on whether the wood is juvenile, sapwood or heartwood, and to wood maturity and microfibril angle. Authors encourage carrying further studies on other populations of A. alba in the Spanish Pyrenees to check if the trends found in this study apply to other provenances.

Safety and health in forest harvesting operations. Diagnosis and preventive actions. A review

Aim of study: to review the present state of the art in relation to the main labour risks and the most relevant results of recent studies evaluating the safety and health conditions of the forest harvesting work and better ways to reduce accidents. Area of study: It focuses mainly on developed Countries, where the general concern about work risks prevention, together with the complex idiosyncrasy of forest work in forest harvesting operations, has led to a growing interest from the forest scientific and technical community. Material and Methods: The main bibliographic and Internet references have been identified using common reference analysis tools. Their conclusions and recommendations have been comprehensively summarized. Main results: Collection of the principal references and their most important conclusions relating to the main accident risk factors, their causes and consequences, the means used towards their prevention, both instrumental as well as in the aspects of training and business management, besides the influence of the growing mechanization of logging operations on those risks. Research highlights: Accident risk is higher in forest harvesting than in most other work sectors, and the main risk factors such as experience, age, seasonality, training, protective equipment, mechanization degree, etc. have been identified and studied. The paper summarizes some relevant results, one of the principal being that the proper entrepreneurial risk management is a key factor leading to the success in minimizing labour risks..

Effect of conservation tillage on soil physical properties, in-situ rainwater harvesting, and erosion control in arid and semi-arid regions

La escasez del agua en las regiones áridas y semiáridas se debe a la escasez de precipitaciones y la distribución desigual en toda la temporada, lo que hace de la agricultura de secano una empresa precaria. Un enfoque para mejorar y estabilizar el agua disponible para la producción de cultivos en estas regiones es el uso de tecnologías de captación de agua de lluvia in situ y su conservación. La adopción de los sistemas de conservación de la humedad del suelo in situ, tales como la labranza de conservación, es una de las estrategias para mejorar la gestión de la agricultura en zonas áridas y semiáridas. El objetivo general de esta tesis ha sido desarrollar una metodología de aplicación de labranza de depósito e investigar los efectos a corto plazo sobre las propiedades físicas del suelo de las diferentes prácticas de cultivo que incluyen labranza de depósito: (reservoir tillage, RT), la laboreo mínimo: (minimum tillage, MT), la no laboreo: (zero tillage, ZT) y laboreo convencional: (conventional tillage, CT) Así como, la retención de agua del suelo y el control de la erosión del suelo en las zonas áridas y semiáridas. Como una primera aproximación, se ha realizado una revisión profunda del estado de la técnica, después de la cual, se encontró que la labranza de depósito es un sistema eficaz de cosecha del agua de lluvia y conservación del suelo, pero que no ha sido evaluada científicamente tanto como otros sistemas de labranza. Los trabajos experimentales cubrieron tres condiciones diferentes: experimentos en laboratorio, experimentos de campo en una región árida, y experimentos de campo en una región semiárida. Para investigar y cuantificar el almacenamiento de agua a temperatura ambiente y la forma en que podría adaptarse para mejorar la infiltración del agua de lluvia recolectada y reducir la erosión del suelo, se ha desarrollado un simulador de lluvia a escala de laboratorio. Las características de las lluvias, entre ellas la intensidad de las precipitaciones, la uniformidad espacial y tamaño de la gota de lluvia, confirmaron que las condiciones naturales de precipitación son simuladas con suficiente precisión. El simulador fue controlado automáticamente mediante una válvula de solenoide y tres boquillas de presión que se usaron para rociar agua correspondiente a diferentes intensidades de lluvia. Con el fin de evaluar el método de RT bajo diferentes pendientes de superficie, se utilizaron diferentes dispositivos de pala de suelo para sacar un volumen idéntico para hacer depresiones. Estas depresiones se compararon con una superficie de suelo control sin depresión, y los resultados mostraron que la RT fue capaz de reducir la erosión del suelo y la escorrentía superficial y aumentar significativamente la infiltración. Luego, basándonos en estos resultados, y después de identificar la forma adecuada de las depresiones, se ha diseñado una herramienta combinada (sistema integrado de labranza de depósito (RT)) compuesto por un arado de una sola línea de chisel, una sola línea de grada en diente de pico, sembradora modificada, y rodillo de púas. El equipo fue construido y se utiliza para comparación con MT y CT en un ambiente árido en Egipto. El estudio se realizó para evaluar el impacto de diferentes prácticas de labranza y sus parámetros de funcionamiento a diferentes profundidades de labranza y con distintas velocidades de avance sobre las propiedades físicas del suelo, así como, la pérdida de suelo, régimen de humedad, la eficiencia de recolección de agua, y la productividad de trigo de invierno. Los resultados indicaron que la RT aumentó drásticamente la infiltración, produciendo una tasa que era 47.51% más alta que MT y 64.56% mayor que la CT. Además, los resultados mostraron que los valores más bajos de la escorrentía y pérdidas de suelos 4.91 mm y 0.65 t ha-1, respectivamente, se registraron en la RT, mientras que los valores más altos, 11.36 mm y 1.66 t ha-1, respectivamente, se produjeron en el marco del CT. Además, otros dos experimentos de campo se llevaron a cabo en ambiente semiárido en Madrid con la cebada y el maíz como los principales cultivos. También ha sido estudiado el potencial de la tecnología inalámbrica de sensores para monitorizar el potencial de agua del suelo. Para el experimento en el que se cultivaba la cebada en secano, se realizaron dos prácticas de labranza (RT y MT). Los resultados mostraron que el potencial del agua del suelo aumentó de forma constante y fue consistentemente mayor en MT. Además, con independencia de todo el período de observación, RT redujo el potencial hídrico del suelo en un 43.6, 5.7 y 82.3% respectivamente en comparación con el MT a profundidades de suelo (10, 20 y 30 cm, respectivamente). También se observaron diferencias claras en los componentes del rendimiento de los cultivos y de rendimiento entre los dos sistemas de labranza, el rendimiento de grano (hasta 14%) y la producción de biomasa (hasta 8.8%) se incrementaron en RT. En el experimento donde se cultivó el maíz en regadío, se realizaron cuatro prácticas de labranza (RT, MT, ZT y CT). Los resultados revelaron que ZT y RT tenían el potencial de agua y temperatura del suelo más bajas. En comparación con el tratamiento con CT, ZT y RT disminuyó el potencial hídrico del suelo en un 72 y 23%, respectivamente, a la profundidad del suelo de 40 cm, y provocó la disminución de la temperatura del suelo en 1.1 y un 0.8 0C respectivamente, en la profundidad del suelo de 5 cm y, por otro lado, el ZT tenía la densidad aparente del suelo y resistencia a la penetración más altas, la cual retrasó el crecimiento del maíz y disminuyó el rendimiento de grano que fue del 15.4% menor que el tratamiento con CT. RT aumenta el rendimiento de grano de maíz cerca de 12.8% en comparación con la ZT. Por otra parte, no hubo diferencias significativas entre (RT, MT y CT) sobre el rendimiento del maíz. En resumen, según los resultados de estos experimentos, se puede decir que mediante el uso de la labranza de depósito, consistente en realizar depresiones después de la siembra, las superficies internas de estas depresiones se consolidan de tal manera que el agua se mantiene para filtrarse en el suelo y por lo tanto dan tiempo para aportar humedad a la zona de enraizamiento de las plantas durante un período prolongado de tiempo. La labranza del depósito podría ser utilizada como un método alternativo en regiones áridas y semiáridas dado que retiene la humedad in situ, a través de estructuras que reducen la escorrentía y por lo tanto puede resultar en la mejora de rendimiento de los cultivos. ABSTRACT Water shortage in arid and semi-arid regions stems from low rainfall and uneven distribution throughout the season, which makes rainfed agriculture a precarious enterprise. One approach to enhance and stabilize the water available for crop production in these regions is to use in-situ rainwater harvesting and conservation technologies. Adoption of in-situ soil moisture conservation systems, such as conservation tillage, is one of the strategies for upgrading agriculture management in arid and semi-arid environments. The general aim of this thesis is to develop a methodology to apply reservoir tillage to investigate the short-term effects of different tillage practices including reservoir tillage (RT), minimum tillage (MT), zero tillage (ZT), and conventional tillage (CT) on soil physical properties, as well as, soil water retention, and soil erosion control in arid and semi-arid areas. As a first approach, a review of the state of the art has been done. We found that reservoir tillage is an effective system of harvesting rainwater and conserving soil, but it has not been scientifically evaluated like other tillage systems. Experimental works covered three different conditions: laboratory experiments, field experiments in an arid region, and field experiments in a semi-arid region. To investigate and quantify water storage from RT and how it could be adapted to improve infiltration of harvested rainwater and reduce soil erosion, a laboratory-scale rainfall simulator was developed. Rainfall characteristics, including rainfall intensity, spatial uniformity and raindrop size, confirm that natural rainfall conditions are simulated with sufficient accuracy. The simulator was auto-controlled by a solenoid valve and three pressure nozzles were used to spray water corresponding to different rainfall intensities. In order to assess the RT method under different surface slopes, different soil scooping devices with identical volume were used to create depressions. The performance of the soil with these depressions was compared to a control soil surface (with no depression). Results show that RT was able to reduce soil erosion and surface runoff and significantly increase infiltration. Then, based on these results and after selecting the proper shape of depressions, a combination implement integrated reservoir tillage system (integrated RT) comprised of a single-row chisel plow, single-row spike tooth harrow, modified seeder, and spiked roller was developed and used to compared to MT and CT in an arid environment in Egypt. The field experiments were conducted to evaluate the impact of different tillage practices and their operating parameters at different tillage depths and different forward speeds on the soil physical properties, as well as on runoff, soil losses, moisture regime, water harvesting efficiency, and winter wheat productivity. Results indicated that the integrated RT drastically increased infiltration, producing a rate that was 47.51% higher than MT and 64.56% higher than CT. In addition, results showed that the lowest values of runoff and soil losses, 4.91 mm and 0.65 t ha-1 respectively, were recorded under the integrated RT, while the highest values, 11.36 mm and 1.66 t ha -1 respectively, occurred under the CT. In addition, two field experiments were carried out in semi-arid environment in Madrid with barley and maize as the main crops. For the rainfed barley experiment, two tillage practices (RT, and MT) were performed. Results showed that soil water potential increased quite steadily and were consistently greater in MT and, irrespective of the entire observation period, RT decreased soil water potential by 43.6, 5.7, and 82.3% compared to MT at soil depths (10, 20, and 30 cm, respectively). In addition, clear differences in crop yield and yield components were observed between the two tillage systems, grain yield (up to 14%) and biomass yield (up to 8.8%) were increased by RT. For the irrigated maize experiment, four tillage practices (RT, MT, ZT, and CT) were performed. Results showed that ZT and RT had the lowest soil water potential and soil temperature. Compared to CT treatment, ZT and RT decreased soil water potential by 72 and 23% respectively, at soil depth of 40 cm, and decreased soil temperature by 1.1 and 0.8 0C respectively, at soil depth of 5 cm. Also, ZT had the highest soil bulk density and penetration resistance, which delayed the maize growth and decreased the grain yield that was 15.4% lower than CT treatment. RT increased maize grain yield about 12.8% compared to ZT. On the other hand, no significant differences among (RT, MT, and CT) on maize yield were found. In summary, according to the results from these experiments using reservoir tillage to make depressions after seeding, these depression’s internal surfaces are consolidated in such a way that the water is held to percolate into the soil and thus allowing time to offer moisture to the plant rooting zone over an extended period of time. Reservoir tillage could be used as an alternative method in arid and semi-arid regions and it retains moisture in-situ, through structures that reduce runoff and thus can result in improved crop yields.

Gestión de la fertilidad de suelos y la nutrición de plantaciones de teca (Tectona grandis L.f.) en América Central

La teca (Tectona grandis L.f.) ha sido tradicionalmente considerada como una madera preciosa en los países del SE Asiático, de donde es originaria, pero durante las últimas décadas ha alcanzado especial relevancia en el sector internacional de las maderas tropicales duras de buena calidad. La especie ha sido ampliamente establecida en América Central, donde tiene una gran importancia socioeconómica, tanto por el impacto de las grandes empresas multinacionales que gestionan grandes plantaciones en la región, como por el gran número de pequeños y medianos propietarios que han elegido esta especie para reforestar sus tierras. Pese a la gran importancia de esta especie, se ha desarrollado relativamente poca investigación acerca de su nutrición y de la gestión del suelo necesaria para su establecimiento y mantenimiento en condiciones sostenibles y productivas. En la presente Tesis Doctoral, tras realizar una amplia revisión bibliográfica, se caracterizan los suelos y la nutrición de las plantaciones de teca en América Central y se proponen varias herramientas para la mejora de su gestión. Las plantaciones de teca de América Central presentan habitualmente deficiencias de K y P, además de algunos problemas de acidez ocasionales. Estos se originan, principalmente, por la mala selección de sitio que se realizó en las últimas dos décadas del siglo XX y por el establecimiento de plantaciones de teca por pequeños propietarios en terrenos que no tienen características propicias para la especie. Además, estos problemas comunes relativos a la baja disponibilidad de P y de K en el suelo son causantes de las relativamente bajas concentraciones foliares de estos elementos (0,88±0,07% K y 0,16±0,04% P) encontradas en plantaciones de teca características de la región. Se presentan varios modelos estadísticos que permiten a los gestores: (a) usarlos como referencia para la interpretación de análisis foliares, ya que ofrecen valores que se consideran característicos de plantaciones de teca con un buen estado nutricional; (b) estimar la cantidad de nutrientes acumulados en la biomasa aérea de sus plantaciones y, sobre todo, su extracción a través de la madera en un aprovechamiento forestal, bien sea una clara o la corta final. La gran acumulación de N, P y K en plantaciones de teca ha de ser considerada como un factor fundamental en su gestión. Además, P y K adquieren mayor relevancia aún ya que su extracción del sistema a través de la madera y su escasa disponibilidad en los suelos hacen que se presente un importante desequilibrio que pone en riesgo la sostenibilidad del sistema. En ese sentido, cambiar la época de cosecha, de la actual (en Enero-Mayo) a Septiembre o Diciembre, puede reducir entre un 24 y un 28% la salida de N asociada a la extracción de madera, un 29% la de P y entre un 14 y un 43% la de K. Se estima que la concentración foliar de P es un factor limitante de la productividad de plantaciones de teca en América Central, proponiéndose un nivel crítico de 0,125%. Además, la teca presenta una tolerancia muy baja a suelos salinos, tendencia que no había sido señalada hasta el momento, siendo muy alta la probabilidad de que la plantación tenga un crecimiento lento o muy lento cuando la Saturación de Na es mayor de 1,1%. Por otro lado, se confirma que K es uno de los elementos clave en la nutrición de las plantaciones de teca en la región centroamericana, proponiéndose un nivel crítico provisional de 3,09% para la Saturación de K, por encima del cual es muy probable que la plantación tenga un crecimiento muy alto. Se ha comprobado que las técnicas estadísticas de análisis multivariante pueden ser usadas como herramientas para agrupar los rodales en base a sus similitudes en cuanto a la fertilidad del suelo y mejorar así el diseño de planes de fertilización en plantaciones con una superficie relativamente grande. De esta manera, se pueden ajustar planes de fertilización más eficientes a escala de grupos de rodales, como un primer paso hacia la selvicultura de precisión, intensificando y diversificando la gestión en función de las diferencias edáficas. Finalmente, aunque los análisis foliares y de suelos indiquen la existencia de deficiencias nutricionales, la fertilización de las plantaciones no siempre va a producir efectos positivos sobre su crecimiento si no se diseña adecuadamente teniendo en cuenta varios factores que pueden estar influyendo negativamente en dicha respuesta, como la densidad de las plantaciones (sinergias con la programación de los clareos y claras) y la elección de la dosis y del producto a aplicar (habitualmente dosis bajas de N-P-K en lugar de incluir otros nutrientes como Mg, B y Zn o usar otros productos como micorrizas, biofertilizantes etc…). ABSTRACT Teak (Tectona grandis L.f.) has been traditionally considered as a precious wood in SE Asia, where it is indigenous. However, during recent decades the species has reached worldwide relevance in the tropical high quality hardwood sector. Teak has been widely established in Central America, where it has become a key species in the forest sector due to its socioeconomic impact, either because of the big-scale plantations of transnational companies and the abundant small-scale plantations established by many farmers. Despite the relevance of the species, little research has been carried out regarding its soil fertility and nutrition management, a key issue both for sustainability and productivity. The present Thesis performs a literature review to this respect, characterize the soil fertility and the nutrition of teak plantations of Central America and propose several management tools. Soil deficiencies of K and P are usually found in teak plantations in Central America, in addition to occasional acidity problems. These problems are mainly derived of (a) a poor site selection performed during 80s and 90s; and (b) small-scale plantations by farmers in sites which are not adequate for the species. These common soil fertility problems related with P and K soil availability are probably the cause of the relatively low P and K foliar concentration (0,88±0,07% K y 0,16±0,04% P) found in representative teak plantations of the region. Several statistical models are proposed, which allow forest managers to: (a) use them as a reference for foliar analysis interpretation, as they show values considered as representative for teak plantations with an adequate nutritional status in the region; (b) estimate the amount of nutrients accumulated in the aerial biomass of the plantations and, especially, the amount of them which are extracted from the systems as wood is harvested in thinning or final clearcuts. The accumulation of N, P and K result in a key factor for teak management in the region. This turns out to be especially relevant for the P and K because their high output rate by timber extraction and the low soil availability result in an important unbalance which constitutes a risk regarding the sustainability of the system. To this respect, modifying the harvesting time from the usual right now (January-May, business as usual scenario) to September or December (proposed alternatives) can reduce between 24 and 28% the N output associated to timber extraction, 29% the P output and between 14 and 43% the K. Foliar P concentration is a main limiting factor for teak plantations productivity in Central America and a 0.125% critical level is proposed. In addition, the results show a very low tolerance for soil salinity, tendency which was not previously reported. Hence, the probability of teak plantations to have low or very low Site Index is high when Na Saturation is higher than 1.1%. On the other hand, K is confirmed as one of the key nutrients regarding teak nutrition in Central America and a 3.09% provisional critical level is proposed for K Saturation; when values are above this level the probability of having very high Site Index is high. Multivariate statistical analyses have been successfully tested to be used as tools to group forest stands according to their soil fertility similarities. Hence, more efficient fertilization plans can be designed for each group of stands, intensifying and diversifying nutritional management according to soil fertility differences. This methodology, which is considered as a first step towards precision forestry, is regarded as helpful tool to design fertilization plans in big scale plantations. Finally, even though foliar and soil analysis would point out some nutritional deficiencies in a forest stand, the results show how the fertilization is not always going to have a positive effect over forest growth if it is not adequately designed. Some factors have been identified as determinants of tree response to fertilization: density (synergisms between fertilization and thinning scheduling) and the appropriate selection of dosages and product (usually low dosages are applied and N-P-K is preferred instead of applying other nutrients such as Mg, B or Zn or using other alternatives such as mycorrhizas or biofertilizers).

Effect of integrated reservoir tillage for in-situ rainwater harvesting and other tillage practices on soil physical properties

There is a need for in-situ soil moisture conservation in arid and semi-arid regions due to insufficient rainfall for agriculture. For this purpose, a combination implement [integrated reservoir tillage system (RT)] comprised of a single-row chisel plow, single-row spike tooth harrow, modified seeder, and spiked roller was developed and compared to the popular tillage practices, viz., minimum tillage (MT) and conventional tillage (CT) in an arid Mediterranean environment in Egypt. The different tillage practices were conducted at tillage depths of 15, 20, and 25 cm and forward speeds of 0.69, 1, 1.25, and 1.53 m s-1. Some soil physical properties, runoff, soil loss, water harvesting efficiency and yield of wheat were evaluated. The different tillage practices caused significant differences in soil physical properties as the RT increased soil infiltration, producing a rate of 48% and 65% higher than that obtained in MT and CT, respectively. The lowest values of runoff and soil loss were recorded under RT as 4.91 mm and 0.65 t ha-1, whereas the highest values were recorded under CT as 11.36 mm and 1.66 t ha-1, respectively. In conclusion, the RT enhanced the infiltration rate, increased water harvesting efficiency, reduced runoff and achieved the highest yield of wheat. The best tillage operating parameters appeared to be at a tillage depth of 20 cm and speed between 1.00 and 1.25 m s-1.

NDT to identify biological damage in wood

Nondestructive techniques are widely used to assess existing timber structures. The models proposed for these methods are usually performed in the laboratory using small clear wood specimens. But in real situations many anomalies, defects and biological damage are found in wood. In these cases the existing models only indicate that the values are outside normality without providing any other information. To solve this problem, a study of non-destructive probing methods for wood was performed, testing the behaviour of four different techniques (penetration resistance, pullout resistance, drill resistance and chip drill extraction) on wood samples with different biological damage, simulating an in-situ test. The wood samples were obtained from existing Spanish timber structures with biotic damage caused by borer insects, termites, brown rot and white rot. The study concludes that all of the methods offer more or less detailed information about the degree of deterioration of wood, but that the first two methods (penetration and pullout resistance) cannot distinguish between pathologies. On the other hand, drill resistance and chip drill extraction make it possible to differentiate pathologies and even to identify species or damage location. Finally, the techniques used were compared to characterize their advantages and disadvantages.

Definición de los procedimientos e indicadores de la cadena de custodia de la industria de pasta y papel vinculados a la normativa ISO 9000/14000

En el trabajo se ha reflejado la génesis del término „desarrollo sostenible‟ y la preocupación social y de los gobiernos hacia la sostenibilidad de los recursos, generando una política forestal a escala internacional, cuyo hito inicial desempeña la Cumbre de Rio y otros procesos, donde surge el término „sostenibilidad‟ - procesos gubernamentales que ponen su atención en los bosques,entre ellos el Proceso paneuropeo del que emanan los Criterios e indicadores de la gestión forestal sostenible, así como otros foros donde aparece la vinculación entre los productos y la sostenibilidad de los bosques de donde proceden. A partir de esos conceptos aparecen los sistemas de certificación, primero FSC, promovido por las ONG ambientalistas, y en respuesta a ello, el sistema PEFC de los propietarios forestales privados con las industrias forestales. En su introducción, el trabajo recoge como surge y evoluciona esta preocupación y como se sucede y desarrollan los sistemas de certificación en España, orientados tanto a la superficie forestal como a sus productos derivados. Tratando de ser una herramienta técnica, en estos últimos quince años, se han ido planteando metodologías y propuestas técnicas que puedan garantizar el origen sostenible del bosque de donde procede la materia prima. Aunque la persistencia de la masa forestal como término tiene importancia, no considera numerosos aspectos incluidos en el concepto “gestión forestal sostenible”. El trabajo manifiesta qué es y cómo se origina la Gestión Forestal Sostenible y muy ligado con ello, el origen de la certificación como herramienta, explicando cómo se incardina la certificación forestal española con las estructuras internacionales y se construyen nuevas estructuras a escala española y autonómica. Se expone el dominio y alcance técnico de la certificación, sus inicios y un análisis de la diversidad de sistemas y etiquetas existentes -como ha ido evolucionando a escala internacional y nacional, por sistemas, sectores y continentes, con especial atención en España, recopilando lo sucedido relevante para el sector forestal, industrias forestales y sistemas de certificación en los años de estudio de elaboración de la tesis. Se refleja la relevancia que adquiere la certificación forestal y de la cadena de custodia para la industria del papel, tanto por las regulaciones, normativas y legislación que involucran al producto derivado del bosque como por ser herramienta que enlaza el bosque sostenible con el consumidor. La aplicación de todas esas especificaciones técnicas que muestran la sostenibilidad del bosque y al trazabilidad en el proceso productivo comporta una carga administrativa de recopilación de información, de control para el seguimiento asociado con los registros necesarios, y de archivo de documentos, conforme a las exigencias que plantean los sistemas de certificación forestal. Por tanto, es importante definir un método y procedimientos genéricos para los correspondientes sistemas de gestión preexistentes en las empresas del sector de pasta y papel (de calidad/ de medio ambiente/integrados), para implantar un Sistema de Cadena de Custodia genérico (común a FSC y PEFC) en una instalación de celulosa y papel y un sistema de diligencia debida. Para ello, ha sido necesario analizar la línea de producción y establecer los puntos de su diagrama en los que se requiere el control de la trazabilidad, puntos en los que se procede al seguimiento y registro de la materia prima, materia semielaborada y producto, y de ahí proceder a redactar o retocar los procedimientos de gestión calidad/ medioambiental, en su caso, para incluir los campos de registro. Según determinen los procedimientos, se efectuará un seguimiento y registro de los, derivados que configuran una característica y se determinará una serie de indicadores del sistema de trazabilidad de la madera en la industria de celulosa y papel, es decir, un conjunto de parámetros cuantitativos y descriptivos, sujetos al seguimiento de forma periódica, que muestren el cambio y permitan observar la evaluación y control del Sistema de Cadena de Custodia. Además de asegurar la trazabilidad de la madera y fibra en la industria de pasta y papel y con ello la sostenibilidad del bosque del que procede, se avalará la legalidad de los aprovechamientos que proporcionan ese recurso maderable, cumpliendo así no sólo la legislación vigente sino también ambos sistemas de certificación FSC y PEFC. El sistema de cadena de custodia de la pasta y papel se caracteriza por los indicadores de seguimiento que permite el control de la trazabilidad. ABSTRACT This paper traces the origins of the term „Sustainable Development‟ and of both citizen and institutional concern for the sustainability of resources, leading to the enactment of a forestry policy at international level, of which the initial milestones are the Rio Summit and other processes in which the term „Sustainability‟ was born. Those forestfocused institutional initiatives include the pan-European process that led to the publication of Sustainable Forest Management Criteria and Indicators, and other forums that highlight the link between finished wood-based products and the sustainability of the forests from which that wood is sourced. Those concepts were the culture in which forest certification systems were engendered, first FSC, promoted by environmental NGOs, and subsequently PEFC, fostered in response to FSC by private forest owners and forest-based industries. In its Introduction, this paper looks at how such concern arose and has evolved and how certification systems came into existence in Spain and developed to encompass both forest lands and forest-based products. As part of a mission to provide an applicable technical tool, new methodologies and technical proposals have been put forward over the past fifteen years aimed at guaranteeing the sustainable origin of the forest from which raw material is sourced. Although the maintenance of forest stands as a term in its own right is important, it does not take many of the aspects included in the concept of “sustainable forest management” into account. This thesis describes what SFM is and how it was born, underlying the close link between SFM and the origin of certification as a tool, explaining how Spanish forest certification is embodied in international structures, while new structures are built here in Spain on both the national and regional scale. This work also details the domain and scope of forest certification from the technical standpoint, explains its beginnings, and assesses the various systems and labels that exist - how certification has evolved internationally and nationally across systems, sectors and continents, with special emphasis on Spain. It provides a compilation of events relevant to forestry, forest industries and forest certification systems that have taken place during the years this thesis has been in preparation. It reflects on the relevance that forest and chain of custody certification holds for the paper industry, in view not only of the regulations, policies and legislation that affect forest-based products but also of its role as a tool that bonds the sustainable forest with the consumer. Implementing the range of technical specifications to demonstrate forest sustainability and traceability throughout the production process entails the administrative burden of collecting information and providing controls to process the relevant records and documents to be kept on file in compliance with the requirements made by forest certification schemes. It is therefore important to define a generic method, together with its relevant procedures,that fits the management systems (quality / environmental / integrated)existing today in pulp and paper companies, in order to implement a generic Chain of Custody scheme (common to FSC and PEFC) in a pulp and paper mill, and a due diligence system. To achieve that, it has first been necessary to analyse the production line and establish points along the route where traceabilitycontrols need to be implemented and points where raw material, semi-finished goods and end products should be monitored and recorded. Subsequently, the procedures in quality / environmental management systems need to be drafted or amended as required to include fields that reflect those records. As required by the procedures, forest-based products that have a specific characteristic shall be monitored and recorded, and a number of indicators identified in the traceability system of wood for pulp & paper, i.e.createa set of quantitative and descriptive parameters subject to regular monitoringthat reveal changes and enable the Chain of Custody system to be assessed and controlled. In addition to ensuring the traceability of wood and fibre in the pulp and paper industry -and so the sustainability of the forest from which it is sourced -, the legality of the harvesting that produces that timber will also be enhanced, thus fulfilling not only the law but also both FSC and PEFC certification schemes. The chain of custody system for pulp and paper is characterised by monitoring indicators that enable traceability to be controlled.

A resistance emulation approach to optimize the wave energy harvesting for a direct drive point absorber

In general, a major challenge for the exploitation of renewable energies is to improve their efficiency. In electricity generation from the energy of ocean waves, not unlike other technologies, the converter must be optimized to make the energy harvesting economically feasible. This paper proposes a passive tuning control strategy of a point absorber in which the power captured is maximized by controlling the electromagnetic force of the generator with a resistance emulation approach. The proposed strategy consists of mapping the optimal values for regular waves and applying them to irregular waves. This strategy is tested in a wave energy converter in which the generator is connected to a boost rectifier converter whose controller is designed to emulate a resistance. The power electronics system implemented is validated by comparing its performance with the case in which the generator is directly connected to a resistive load. The simulation results show the effectiveness of the proposed strategy as the maximum captured power is concentrated around the optimal values previously calculated and with the same behavior for both excitations.