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.

Problem??tica de la formaci??n profesional espec??fica

Se presenta experiencia educativa que propone la creaci??n de un grupo de trabajo para analizar la problem??tica de la formaci??n profesional y proponer mejoras. Se realiza en el IES Padre P??veda en Guadix, Granada. Los objetivos son: seguimiento del cat??logo nacional de las cualificaciones profesionales y de los nuevos t??tulos de formaci??n profesional que afecta directamente a nuestro alumnado; estudiar la necesidad de implantar nuevos ciclos formativos en nuestra comunidad relacionados con la demanda de alumnado; estudiar el equilibrio o desequilibrio entre los distintos subsistemas de formaci??n profesional, e intentar evitar un estancamiento en la formaci??n profesional espec??fica; impulsar el establecimiento de los centros integrados en Andaluc??a; estudiar y analizar la legislaci??n vigente, difundi??ndola a toda nuestra comunidad escolar; analizar el plan Andaluz de formaci??n profesional; elaborar informes donde se reflejen los resultados de nuestro trabajo y darle la mayor difusi??n posible.

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.

The Logical Problem of Language Change

This paper considers the problem of language change. Linguists must explain not only how languages are learned but also how and why they have evolved along certain trajectories and not others. While the language learning problem has focused on the behavior of individuals and how they acquire a particular grammar from a class of grammars ${cal G}$, here we consider a population of such learners and investigate the emergent, global population characteristics of linguistic communities over several generations. We argue that language change follows logically from specific assumptions about grammatical theories and learning paradigms. In particular, we are able to transform parameterized theories and memoryless acquisition algorithms into grammatical dynamical systems, whose evolution depicts a population's evolving linguistic composition. We investigate the linguistic and computational consequences of this model, showing that the formalization allows one to ask questions about diachronic that one otherwise could not ask, such as the effect of varying initial conditions on the resulting diachronic trajectories. From a more programmatic perspective, we give an example of how the dynamical system model for language change can serve as a way to distinguish among alternative grammatical theories, introducing a formal diachronic adequacy criterion for linguistic theories.

Hierarchical Mixtures of Experts and the EM Algorithm

We present a tree-structured architecture for supervised learning. The statistical model underlying the architecture is a hierarchical mixture model in which both the mixture coefficients and the mixture components are generalized linear models (GLIM's). Learning is treated as a maximum likelihood problem; in particular, we present an Expectation-Maximization (EM) algorithm for adjusting the parameters of the architecture. We also develop an on-line learning algorithm in which the parameters are updated incrementally. Comparative simulation results are presented in the robot dynamics domain.

Electrical Design: A Problem for Artificial Intelligence Research

This report outlines the problem of intelligent failure recovery in a problem-solver for electrical design. We want our problem solver to learn as much as it can from its mistakes. Thus we cast the engineering design process on terms of Problem Solving by Debugging Almost-Right Plans, a paradigm for automatic problem solving based on the belief that creation and removal of "bugs" is an unavoidable part of the process of solving a complex problem. The process of localization and removal of bugs called for by the PSBDARP theory requires an approach to engineering analysis in which every result has a justification which describes the exact set of assumptions it depends upon. We have developed a program based on Analysis by Propagation of Constraints which can explain the basis of its deductions. In addition to being useful to a PSBDARP designer, these justifications are used in Dependency-Directed Backtracking to limit the combinatorial search in the analysis routines. Although the research we will describe is explicitly about electrical circuits, we believe that similar principles and methods are employed by other kinds of engineers, including computer programmers.

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.

Alternative ways to estimate change points in multinomial sequences. An application to an authorship attribution problem

The statistical analysis of literary style is the part of stylometry that compares measurable characteristics in a text that are rarely controlled by the author, with those in other texts. When the goal is to settle authorship questions, these characteristics should relate to the author’s style and not to the genre, epoch or editor, and they should be such that their variation between authors is larger than the variation within comparable texts from the same author. For an overview of the literature on stylometry and some of the techniques involved, see for example Mosteller and Wallace (1964, 82), Herdan (1964), Morton (1978), Holmes (1985), Oakes (1998) or Lebart, Salem and Berry (1998). Tirant lo Blanc, a chivalry book, is the main work in catalan literature and it was hailed to be “the best book of its kind in the world” by Cervantes in Don Quixote. Considered by writters like Vargas Llosa or Damaso Alonso to be the first modern novel in Europe, it has been translated several times into Spanish, Italian and French, with modern English translations by Rosenthal (1996) and La Fontaine (1993). The main body of this book was written between 1460 and 1465, but it was not printed until 1490. There is an intense and long lasting debate around its authorship sprouting from its first edition, where its introduction states that the whole book is the work of Martorell (1413?-1468), while at the end it is stated that the last one fourth of the book is by Galba (?-1490), after the death of Martorell. Some of the authors that support the theory of single authorship are Riquer (1990), Chiner (1993) and Badia (1993), while some of those supporting the double authorship are Riquer (1947), Coromines (1956) and Ferrando (1995). For an overview of this debate, see Riquer (1990). Neither of the two candidate authors left any text comparable to the one under study, and therefore discriminant analysis can not be used to help classify chapters by author. By using sample texts encompassing about ten percent of the book, and looking at word length and at the use of 44 conjunctions, prepositions and articles, Ginebra and Cabos (1998) detect heterogeneities that might indicate the existence of two authors. By analyzing the diversity of the vocabulary, Riba and Ginebra (2000) estimates that stylistic boundary to be near chapter 383. Following the lead of the extensive literature, this paper looks into word length, the use of the most frequent words and into the use of vowels in each chapter of the book. Given that the features selected are categorical, that leads to three contingency tables of ordered rows and therefore to three sequences of multinomial observations. Section 2 explores these sequences graphically, observing a clear shift in their distribution. Section 3 describes the problem of the estimation of a suden change-point in those sequences, in the following sections we propose various ways to estimate change-points in multinomial sequences; the method in section 4 involves fitting models for polytomous data, the one in Section 5 fits gamma models onto the sequence of Chi-square distances between each row profiles and the average profile, the one in Section 6 fits models onto the sequence of values taken by the first component of the correspondence analysis as well as onto sequences of other summary measures like the average word length. In Section 7 we fit models onto the marginal binomial sequences to identify the features that distinguish the chapters before and after that boundary. Most methods rely heavily on the use of generalized linear models

Application of discriminant function analysis and change-point problem in dating volcanic ashes

The application of Discriminant function analysis (DFA) is not a new idea in the study of tephrochrology. In this paper, DFA is applied to compositional datasets of two different types of tephras from Mountain Ruapehu in New Zealand and Mountain Rainier in USA. The canonical variables from the analysis are further investigated with a statistical methodology of change-point problems in order to gain a better understanding of the change in compositional pattern over time. Finally, a special case of segmented regression has been proposed to model both the time of change and the change in pattern. This model can be used to estimate the age for the unknown tephras using Bayesian statistical calibration

Educaci??n ambiental para la acci??n ciudadana : concepciones del profesorado en formaci??n sobre la problem??tica de la energ??a

Determinar el alcance de los objetivos y la naturaleza de las concepciones que tienen los-as estudiantes y los materiales did??cticos, sobre la tem??tica de la energ??a, se formula los siguientes problemas: 1. ??Cu??les son las concepciones de los-las estudiantes de Magisterio sobre los modelos de Educaci??n Ambiental? 2. ??Cu??les son las concepciones de los-las estudiantes sobre los problemas socioambientales que consideran m??s importantes y la idea de riesgo asociada a los mismos? 3. ??Cu??les son las concepciones de los-las estudiantes sobre el papel que juega la participaci??n en el proceso de Educaci??n Ambiental? 4. ??Cu??les son las concepciones de los-las estudiantes sobre la energ??a y el papel que juega la energ??a como problema socioambiental? 5. ??Cu??les son las concepciones did??cticas dominantes de los-las estudiantes sobre el tratamiento did??ctico de la energ??a? 6. ??Cu??les son las concepciones did??cticas dominantes de los materiales seleccionados sobre el tratamiento de la energ??a? 7. ??Existe alguna correspondencia entre las concepciones de los-las estudiantes y las concepciones did??cticas de los materiales seleccionados sobre el tratamiento did??ctico de la energ??a? 8. ??Existen diferencias en las concepciones de los-las estudiantes sobre algunos aspectos de la Educaci??n Ambiental y de la energ??a dependiendo del momento de la investigaci??n? 9. ??Existe coherencia en las concepciones de los-las estudiantes y de los materiales?. El paradigma metodol??gico elegido se ubica en la definici??n del paradigma interpretativo, denominado tambi??n naturalista, de enfoque ecol??gico o etnogr??fico, a trav??s de un estudio de caso. Se selecciona un grupo de estudiantes de la Facultad de Ciencias de la Educaci??n de la Universidad de Sevilla, de las modalidades de Educaci??n Primaria y Especial, que cursan la asignatura optativa de Educaci??n Ambiental (EA). La muestra se compone de 12 hombres y 38 mujeres, sumando un total de 50 personas, solo se tiene materiales escritos de forma individual de 45 personas, se agrupan para trabajar de forma conjunta formando 12 grupos. Dentro del planteamiento metodol??gico adoptado, se utiliza diferentes t??cnicas e instrumentos: la b??squeda y an??lisis de materiales de EA desde un punto de vista did??ctico. Observaci??n externa y recogida de informaci??n en el diario de clase. Cuestionarios y documentos de trabajo. Grabaciones de algunas sesiones de clase. Grupo de discusi??n. Para el tratamiento de los datos se dise??a un sistema de categor??as que sistematizara las respuestas. Las respuestas m??s encontradas, sobre el modelo de EA y el car??cter interdisciplinar, se encuentran en los valores m??s simples respecto a los valores considerados en el sistema de categor??as creados, los cuales mayoritariamente vinculan la EA con un modelo conservacionista y con actividades puntuales, lo cual indica que lo que entiende los-as educadores-as ambientales sobre EA, suele estar 'identificado con el amor a la naturaleza, con las salidas fuera del aula, generalmente 'al campo', con la recogida de muestras o la realizaci??n de an??lisis o reciclado de papel' y 'ven la Educaci??n Ambiental como algo ajeno a las dem??s materias que se lleva a cabo en algunas determinadas fechas y que debe tener un curr??culo establecido y diferente del de otras materias, a excepci??n de las ciencias naturales, con las que de alguna manera se liga la Educaci??n Ambiental y aparece una alta relaci??n entre esta visi??n de la EA y la corriente inductivista del aprendizaje'.

Multicast extension of unicast charging for QoS Services

In order to successfully deploy multicast services in QoS-aware networks, pricing architectures must take into account the particular characteristics of multicast sessions. With this objective, we propose a charging scheme for QoS multicast services, assuming that the unicast cost of each interconnecting link is determined and that such cost is expressed in terms of quality of service (QoS) parameters. Our scheme allows determining the cost distribution of a multicast session along a cost distribution tree (CDT), and basing such distribution in those pre-existing unicast cost functions. The paper discusses in detail the main characteristics of the problem in a realistic interdomain scenario and how the proposed scheme would contribute to its solution

On the use of QoS requirements as base of multicast charging

We propose a charging scheme for cost distribution along a multicast tree when cost is the responsibility of the receivers. This scheme focuses on QoS considerations and it does not depend on any specific type of service. The scheme has been designed to be used as a bridge between unicast and multicast services, solving the problem of charging multicast services by means of unicast charging and existing QoS routing mechanisms. We also include a numerical comparison and discussions of the case of non-numerical or relative QoS and on the application to some service examples in order to give a better understanding of the proposal

La escuela rural en Catalu??a : problem??ticas, propuestas y retos de futuro

Resumen tomado de la publicaci??n

??Formaci??n en la empresa? problem??tica, perspectivas

Resumen del autor. Res??menes en espa??ol e ingl??s