Alley cropping of willows and grassland for bioenergy provision: productivity, tree-crop interactions and energy balance

The demand for biomass for bioenergy has increased rapidly in industrialized countries in the recent years. Biogenic energy carriers are known to reduce CO2 emissions. However, the resource-inefficient production of biomass often caused negative impacts on the environment, e.g. biodiversity losses, nitrate leaching, and erosion. The detrimental effects evolved mainly from annual crops. Therefore, the aim of modern bioenergy cropping systems is to combine yield stability and environmental benefits by the establishment of mixed-cropping systems. A particular emphasis is on perennial crops which are perceived as environmentally superior to annual crops. Agroforestry systems represent such mixed perennial cropping systems and consist of a mix of trees and arable crops or grassland within the same area of land. Agroforestry practices vary across the globe and alley cropping is a type of agroforestry system which is well adapted to the temperate zone, with a high degree of mechanization. Trees are planted in rows and crops are planted in the alleyways, which facilitates their management by machinery. This study was conducted to examine a young alley cropping system of willows and two grassland mixtures for bioenergy provision under temperate climate conditions. The first part of the thesis identified possible competition effects between willows and the two grassland mixtures. Since light seemed to be the factor most affecting the yield performance of the understory in temperate agroforestry systems, a biennial in situ artificial shade experiment was established over a separate clover-grass stand to quantify the effects of shade. Data to possible below- and aboveground interactions among willows and the two grassland mixtures and their effects on productivity, sward composition, and quality were monitored along a tree-grassland interface within the alleys. In the second part, productivity of the alley cropping system was examined on a triennial time frame and compared to separate grassland and willow stands as controls. Three different conversion technologies (combustion of hay, integrated generation of solid fuel and biogas from biomass, whole crop digestion) were applied to grassland biomass as feedstock and analyzed for its energetic potential. The energetic potential of willow wood chips was calculated by applying combustion as conversion technique. Net energy balances of separate grassland stands, agroforestry and pure willow stands evaluated their energy efficiency. Results of the biennial artificial shade experiment showed that severe shade (80 % light reduction) halved grassland productivity on average compared to a non-shaded control. White clover as heliophilous plant responded sensitively to limited radiation and its dry matter contribution in the sward decreased with increasing shade, whereas non-leguminous forbs (mainly segetal species) benefited. Changes in nutritive quality could not be confirmed by this experiment. Through the study on interactions within the alleys of the young agroforestry system it was possible to outline changes of incident light, soil temperature and sward composition of clover-grass along the tree-grassland interface. Nearly no effects of trees on precipitation, soil moisture and understory productivity occurred along the interface during the biennial experiment. Considering the results of the productivity and the net energy yield alley cropping system had lower than pure grassland stands, irrespective of the grassland seed mixture or fertilization, but was higher than that for pure willow stands. The comparison of three different energetic conversion techniques for the grassland biomass showed highest net energy yields for hay combustion, whereas the integrated generation of solid fuel and biogas from biomass (IFBB) and whole crop digestion performed similarly. However, due to the low fuel quality of hay, its direct combustion cannot be recommended as a viable conversion technique, whereas IFBB fuels were of a similar quality to wood chip from willow.

Fat-Tree Routing for Transit

The Transit network provides high-speed, low-latency, fault-tolerant interconnect for high-performance, multiprocessor computers. The basic connection scheme for Transit uses bidelta style, multistage networks to support up to 256 processors. Scaling to larger machines by simply extending the bidelta network topology will result in a uniform degradation of network latency between all processors. By employing a fat-tree network structure in larger systems, the network provides locality and universality properties which can help minimize the impact of scaling on network latency. This report details the topology and construction issues associated with integrating Transit routing technology into fat-tree interconnect topologies.

FastAero – A Precorrected FFT – Fast Multipole Tree Steady and Unsteady Potential Flow Solver

In this paper a precorrected FFT-Fast Multipole Tree (pFFT-FMT) method for solving the potential flow around arbitrary three dimensional bodies is presented. The method takes advantage of the efficiency of the pFFT and FMT algorithms to facilitate more demanding computations such as automatic wake generation and hands-off steady and unsteady aerodynamic simulations. The velocity potential on the body surfaces and in the domain is determined using a pFFT Boundary Element Method (BEM) approach based on the Green’s Theorem Boundary Integral Equation. The vorticity trailing all lifting surfaces in the domain is represented using a Fast Multipole Tree, time advected, vortex participle method. Some simple steady state flow solutions are performed to demonstrate the basic capabilities of the solver. Although this paper focuses primarily on steady state solutions, it should be noted that this approach is designed to be a robust and efficient unsteady potential flow simulation tool, useful for rapid computational prototyping.

Modeling of hybrid systems by piecewise decomposition

Piecewise linear models systems arise as mathematical models of systems in many practical applications, often from linearization for nonlinear systems. There are two main approaches of dealing with these systems according to their continuous or discrete-time aspects. We propose an approach which is based on the state transformation, more particularly the partition of the phase portrait in different regions where each subregion is modeled as a two-dimensional linear time invariant system. Then the Takagi-Sugeno model, which is a combination of local model is calculated. The simulation results show that the Alpha partition is well-suited for dealing with such a system

ALPS Workshop 2 p2 Mentoring tree

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Oaxaca-Blinder type counterfactual decomposition methods for duration outcomes

Los métodos disponibles para realizar análisis de descomposición que se pueden aplicar cuando los datos son completamente observados, no son válidos cuando la variable de interés es censurada. Esto puede explicar la escasez de este tipo de ejercicios considerando variables de duración, las cuales se observan usualmente bajo censura. Este documento propone un método del tipo Oaxaca-Blinder para descomponer diferencias en la media en el contexto de datos censurados. La validez de dicho método radica en la identificación y estimación de la distribución conjunta de la variable de duración y un conjunto de covariables. Adicionalmente, se propone un método más general que permite descomponer otros funcionales de interés como la mediana o el coeficiente de Gini, el cual se basa en la especificación de la función de distribución condicional de la variable de duración dado un conjunto de covariables. Con el fin de evaluar el desempeño de dichos métodos, se realizan experimentos tipo Monte Carlo. Finalmente, los métodos propuestos son aplicados para analizar las brechas de género en diferentes características de la duración del desempleo en España, tales como la duración media, la probabilidad de ser desempleado de largo plazo y el coeficiente de Gini. Los resultados obtenidos permiten concluir que los factores diferentes a las características observables, tales como capital humano o estructura del hogar, juegan un papel primordial para explicar dichas brechas.

Tree frogs.

La selva es el hogar de más de la mitad de los animales del mundo desde diminutos insectos a los grandes mamíferos pretende enseñar a los niños el ciclo de vida de las ranas arbóreas y la forma en que interactúan con su entorno, sus hábitos , su estilo de vida y las amenazas a los que se enfrenta por la actuación de los hombres al modificar las condiciones ambientales. La obra contiene un mapa de distribución de su hábitat, glosario y bibliografía.

Tree trogs.

Examina las características distintivas, ciclo de vida, la caza y la conducta de alimentación, hibernación, mecanismos de defensa de diferentes tipos de ranas de árboles. Incluye un glosario.

The dragon tree.

Pertenece a un amplio programa infantil de lectura que abarca distintos niveles de edad y, por tanto, de conocimientos. Se abordan las necesidades de lectura en los niños y la amplia variedad de habilidades que necesitan adquirir para su aprendizaje y, se destaca, también, la importancia de la narración en las historias. Los niños protagonistas viven una aventura fantástica con un dragón que vive en un árbol.

Oxford reading tree. Teacher's guide 5 : robins and jackdaws stages 6-11.

Guía del profesor con recursos fotocopiables, para proporcionar más posibilidades a los niños con una capacidad por encima de la media y que pueden hacer frente a una mayor complejidad narrativa. Ofrece más de un género literario y un texto más maduro. Nuevas actividades, incluidas la comprensión, gramática, puntuación, y escritura creativa. Lista de libros para la lectura adicional.

Oxford reading tree. Teacher's guide 4 : woodpeckers : stages 3-9.

Da explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo linguístico. Contiene actividades de apoyo a una serie de estrategiás de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 3 : owls and magpies : stages 6-9.

Da explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo linguístico. Contiene actividades de apoyo a una serie de estrategiás de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 2 : stages 4-5.

Explicaciones detalladas de cómo sacar el máximo provecho de cada etapa. Las ideas y sugerencias de esta guía mantienen y amplían la filosofía de la lectura, y el programa, según la propuesta de métodos de enseñanza establecidos en la guía del primer nivel, que ayudarán a dar a los niños la confianza, y las habilidades necesarias para hacer frente a historias con textos más extensos y complejos. Contiene actividades de apoyo a una serie de estrategias de lectura, recursos fotocopiables, actividades tranversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Oxford reading tree. Teacher's guide 1 : stages 1-3.

Explicaciones detalladas para ayudar a los niños a aprender a leer en las primeras etapas. Facilita al profesor una serie de estrategias para la enseñanza de la lectura y una amplia variedad de recursos y materiales de apoyo lingüístico. Contiene actividades de apoyo a una serie de estrategias de lectura, recursos fotocopiables, actividades transversales de los contenidos curriculares, evaluación con hojas de registro. También incluye material adicional.

Two complementary molecular energy decomposition schemes: the Mayer and Ziegler-Rauk methods in comparison

In the present paper we discuss and compare two different energy decomposition schemes: Mayer's Hartree-Fock energy decomposition into diatomic and monoatomic contributions [Chem. Phys. Lett. 382, 265 (2003)], and the Ziegler-Rauk dissociation energy decomposition [Inorg. Chem. 18, 1558 (1979)]. The Ziegler-Rauk scheme is based on a separation of a molecule into fragments, while Mayer's scheme can be used in the cases where a fragmentation of the system in clearly separable parts is not possible. In the Mayer scheme, the density of a free atom is deformed to give the one-atom Mulliken density that subsequently interacts to give rise to the diatomic interaction energy. We give a detailed analysis of the diatomic energy contributions in the Mayer scheme and a close look onto the one-atom Mulliken densities. The Mulliken density ρA has a single large maximum around the nuclear position of the atom A, but exhibits slightly negative values in the vicinity of neighboring atoms. The main connecting point between both analysis schemes is the electrostatic energy. Both decomposition schemes utilize the same electrostatic energy expression, but differ in how fragment densities are defined. In the Mayer scheme, the electrostatic component originates from the interaction of the Mulliken densities, while in the Ziegler-Rauk scheme, the undisturbed fragment densities interact. The values of the electrostatic energy resulting from the two schemes differ significantly but typically have the same order of magnitude. Both methods are useful and complementary since Mayer's decomposition focuses on the energy of the finally formed molecule, whereas the Ziegler-Rauk scheme describes the bond formation starting from undeformed fragment densities