On the specification and testing of inverters for stand-alone PV systems

Inverter features are reviewed from a PV systems perspective, with a view to contributing to possible codes, procurement specifications and testing procedures, in order to assure the technical quality of these systems. A laboratory testing campaign has been carried out on a representative set of sixteen currently available inverters and a set of the most common AC appliances. The results of the tests are discussed with the aim of divulging the particular features of operating AC appliances in PV systems and the provisions to be taken into account in PV system design. The development of testing procedures has followed the motto ?keep it as simple as possible?, in order to make their application easier in conventional laboratories in developing countries.

Field analysis of solar PV-based collective systems for rural electrification.

This article analyses the long-term performance of collective off-grid photovoltaic (PV) systems in rural areas. The use of collective PV systems for the electrification of small medium-size villages in developing countries has increased in the recent years. They are basically set up as stand-alone installations (diesel hybrid or pure PV) with no connection with other electrical grids. Their particular conditions (isolated) and usual installation places (far from commercial/industrial centers) require an autonomous and reliable technology. Different but related factors affect their performance and the energy supply; some of them are strictly technical but others depend on external issues like the solar energy resource and users’ energy and power consumption. The work presented is based on field operation of twelve collective PV installations supplying the electricity to off-grid villages located in the province of Jujuy, Argentina. Five of them have PV generators as unique power source while other seven include the support of diesel groups. Load demand evolution, energy productivity and fuel consumption are analyzed. Besides, energy generation strategies (PV/diesel) are also discussed.

On the Extension of the Analytic Nodal Diffusion Solver ANDES to Sodium Fast Reactors

Within the framework of the Collaborative Project for a European Sodium Fast Reactor, the reactor physics group at UPM is working on the extension of its in-house multi-scale advanced deterministic code COBAYA3 to Sodium Fast Reactors (SFR). COBAYA3 is a 3D multigroup neutron kinetics diffusion code that can be used either as a pin-by-pin code or as a stand-alone nodal code by using the analytic nodal diffusion solver ANDES. It is coupled with thermalhydraulics codes such as COBRA-TF and FLICA, allowing transient analysis of LWR at both fine-mesh and coarse-mesh scales. In order to enable also 3D pin-by-pin and nodal coupled NK-TH simulations of SFR, different developments are in progress. This paper presents the first steps towards the application of COBAYA3 to this type of reactors. ANDES solver, already extended to triangular-Z geometry, has been applied to fast reactor steady-state calculations. The required cross section libraries were generated with ERANOS code for several configurations. The limitations encountered in the application of the Analytic Coarse Mesh Finite Difference (ACMFD) method –implemented inside ANDES– to fast reactors are presented and the sensitivity of the method when using a high number of energy groups is studied. ANDES performance is assessed by comparison with the results provided by ERANOS, using a mini-core model in 33 energy groups. Furthermore, a benchmark from the NEA for a small 3D FBR in hexagonal-Z geometry and 4 energy groups is also employed to verify the behavior of the code with few energy groups.

Fiabilidad de los sistemas fotovoltaicos autónomos

Los sistemas fotovoltaicos autónomos, es decir, sistemas que carecen de conexión a la red eléctrica, presentan una gran utilidad para poder llevar a cabo la electrificación de lugares remotos donde no hay medios de acceder a la energía eléctrica. El continuo avance en el número de sistemas instalados por todo el mundo y su continua difusión técnica no significa que la implantación de estas instalaciones no presente ninguna problemática. A excepción del panel fotovoltaico que presenta una elevada fiabilidad, el resto de elementos que forman el sistema presentan numerosos problemas y dependencias, por tanto el estudio de las fiabilidades de estos elementos es obligado. En este proyecto se pretende analizar y estudiar detalladamente la fiabilidad de los sistemas fotovoltaicos aislados. Primeramente, el presente documento ofrece una introducción sobre la situación mundial de las energías renovables, así como una explicación detallada de la energía fotovoltaica. Esto incluye una explicación técnica de los diferentes elementos que forman el sistema energético (módulo fotovoltaico, batería, regulador de carga, inversor, cargas, cableado y conectores). Por otro lado, se hará un estudio teórico del concepto de fiabilidad, con sus definiciones y parámetros más importantes. Llegados a este punto, el proyecto aplica la teoría de fiabilidad comentada a los sistemas fotovoltaicos autónomos, profundizando en la fiabilidad de cada elemento del sistema así como evaluando el conjunto. Por último, se muestran datos reales de fiabilidad de programas de electrificación, demostrando la variedad de resultados sujetos a los distintos emplazamientos de las instalaciones y por tanto distintas condiciones de trabajo. Se destaca de esta forma la importancia de la fiabilidad de los sistemas fotovoltaicos autónomos, pues normalmente este tipo de instalaciones se localizan en emplazamientos remotos, sin personal cualificado de mantenimiento cercano ni grandes recursos logísticos y económicos. También se resalta en el trabajo la dependencia de la radiación solar y el perfil de consumo a la hora de dimensionar el sistema. Abstract Stand-alone photovoltaic systems which are not connected to the utility grid. These systems are very useful to carry out the electrification of remote locations where is no easy to access to electricity. The number increased of systems installed worldwide and their continued dissemination technique does not mean that these systems doesn´t fails. With the exception of the photovoltaic panel with a high reliability, the remaining elements of the system can to have some problems and therefore the study of the reliabilities of these elements is required. This project tries to analyze and study the detaila of the reliability of standalone PV systems. On the one hand, this paper provides an overview of the global situation of renewable energy, as well as a detailed explanation of photovoltaics. This includes a technical detail of the different elements of the energy system (PV module, battery, charge controller, inverter, loads, wiring and connectors). In addition, there will be a theoricall study of the concept of reliability, with the most important definitions and key parameters. On the other hand, the project applies the reliability concepts discussed to the stand-alone photovoltaic systems, analyzing the reliability of each element of the system and analyzing the entire system. Finally, this document shows the most important data about reliability of some electrification programs, checking the variety of results subject to different places and different conditions. As a conclussion, the importance of reliability of stand-alone photovoltaic systems because usually these are located in remote locations, without qualified maintenance and financial resources.These systems operate under dependence of solar radiation and the consumption profile.

The ciao prolog system

Ciao is a public domain, next generation multi-paradigm programming environment with a unique set of features: Ciao offers a complete Prolog system, supporting ISO-Prolog, but its novel modular design allows both restricting and extending the language. As a result, it allows working with fully declarative subsets of Prolog and also to extend these subsets (or ISO-Prolog) both syntactically and semantically. Most importantly, these restrictions and extensions can be activated separately on each program module so that several extensions can coexist in the same application for different modules. Ciao also supports (through such extensions) programming with functions, higher-order (with predicate abstractions), constraints, and objects, as well as feature terms (records), persistence, several control rules (breadth-first search, iterative deepening, ...), concurrency (threads/engines), a good base for distributed execution (agents), and parallel execution. Libraries also support WWW programming, sockets, external interfaces (C, Java, TclTk, relational databases, etc.), etc. Ciao offers support for programming in the large with a robust module/object system, module-based separate/incremental compilation (automatically -no need for makefiles), an assertion language for declaring (optional) program properties (including types and modes, but also determinacy, non-failure, cost, etc.), automatic static inference and static/dynamic checking of such assertions, etc. Ciao also offers support for programming in the small producing small executables (including only those builtins used by the program) and support for writing scripts in Prolog. The Ciao programming environment includes a classical top-level and a rich emacs interface with an embeddable source-level debugger and a number of execution visualization tools. The Ciao compiler (which can be run outside the top level shell) generates several forms of architecture-independent and stand-alone executables, which run with speed, efficiency and executable size which are very competive with other commercial and academic Prolog/CLP systems. Library modules can be compiled into compact bytecode or C source files, and linked statically, dynamically, or autoloaded. The novel modular design of Ciao enables, in addition to modular program development, effective global program analysis and static debugging and optimization via source to source program transformation. These tasks are performed by the Ciao preprocessor ( ciaopp, distributed separately). The Ciao programming environment also includes lpdoc, an automatic documentation generator for LP/CLP programs. It processes Prolog files adorned with (Ciao) assertions and machine-readable comments and generates manuals in many formats including postscript, pdf, texinfo, info, HTML, man, etc. , as well as on-line help, ascii README files, entries for indices of manuals (info, WWW, ...), and maintains WWW distribution sites.

Airport Taxi Planning: Lagrangian Decomposition

The airport taxi planning (TP) module is a decision tool intended to guide airport surface management operations. TP is defined by a flow network optimization model that represents flight ground movements and improves aircraft taxiing routes and schedules during periods of aircraft congestion. TP is not intended to operate as a stand‐alone tool for airport operations management: on the contrary, it must be used in conjunction with existing departing and arriving traffic tools and overseen by the taxi planner of the airport, also known as the aircraft ground controller. TP must be flexible in order to accommodate changing inputs while maintaining consistent routes and schedules already delivered from past executions. Within this dynamic environment, the execution time of TP may not exceed a few minutes. Classic methods for solving binary multi‐commodity flow networks with side constraints are not efficient enough; therefore, a Lagrangian decomposition methodology has been adapted to solve it. We demonstrate TP Lagrangian decomposition using actual data from the Madrid‐Barajas Airport

The NACIR Project: New Applications for CPV'S: A fast way to improve reliability and Technology progress

The main goal of this proposal is to join together the owners of the most advanced CPV technology, with respect to the state of the art, in order to research from its leading position new applications for CPV systems. In addition to opening up new markets, it will unveil possible sources of failure in new environments outside Europe, in order to assure component reliability. The proposed project will also try to improve the current technology of the industrial partners (ISOFOTON and CONCENTRIX) by accelerating the learning curve that CPV must follow in order to reach the competitive market, and lowering the cost under the current flat panel PV significantly within 3-4 years. The use of CPV systems in remote areas, together with harsher radiation, ambient and infrastructure conditions will help to increase the rate of progress of this technology. In addition, the ISFOC s contribution, which brings together seven power plants from seven CPV technologies up to 3 MWpeak, will allow creating the most complete database of components and systems performance to be generated as well as the effects of radiation and meteorology on systems operations. Finally, regarding the new applications for CPV subject, the project will use a CPV system sized 25 kWp in a stand-alone station in Egypt (NWRC) for the first time for water pumping and irrigation purposes. In a similar way ISOFOTON will connect up to 25 kWp CPV to the Moroccan ONE utility grid. From the research content point of view of this project, which is directly addressed by the scope of the call, the cooperative research between UPM, FhG-ISE and the two companies will be favoured by the fact that all are progressing in similar directions: developing two-stage optics CPV systems. In addition to these technology improvements the UPM is very interested in developing a new concept of module, recently patented, which will fulfil all required characteristics of a good CPV with less components and reducing cost.

Modifications in the Dynamic Properties of a Structure due to Human Actions

The interest for modelling of human actions acting on structures has been recurrent since the first accidents on suspension bridges in the nineteenth century such as Broughton (1831) in the U.K. or Angers (1850) in France. Stadiums, gymnasiums are other types of structure where human induced vibration is very important. In these structures a particular phenomenon appears such as the interaction personstructure (lock-in), the person-person synchronization, and the influence of the mass and damping of the people in the structural behaviour. This paper focuses on the latter topic. In order to evaluate these property modifications several tests have been carried out on a stand-alone building. For the test an electro-dynamic shaker was installed at a fixed point of the gym slab and different groups of people were located around the shaker. The dynamic characteristics of the structure without people inside have been calculated by two methods: using a three-dimensional finite element model of the building and by operational modal analysis. These calculated experimental and numerical values are the reference values used to evaluate the modifications in the dynamic properties of the structure.

Desarrollo e implementación de un sistema robótico aéreo con programación tridimensional orientado al recorrido de rutas

En la actualidad se estudia en numerosos campos cómo automatizar distintas tareas ejecutadas por aeronaves con tripulación humana. Estas tareas son en todos los casos muy costosos, debido al gran consumo de combustible, gran coste de adquisición y mantenimiento de la propia aeronave, todo ello sin contar el riesgo para los mismos tripulantes. Como ejemplo de estas tareas se puede incluir la vigilancia policial y fronteriza, revisiones de tendidos de alta tensión, la alerta temprana de incendios forestales y la medición de parámetros contaminantes. El objetivo de este proyecto es el diseño y la construcción de un prototipo electrónico empotrado basado en microcontrolador con núcleo C8051 de Silicon labs, que sea capaz de gobernar una aeronave de radiocontrol de forma transparente, de manera que en un futuro se pueda sustituir el propio aeromodelo, con la modificación de algunos parámetros, para poder incorporar sistemas de video o distintos medios de detección de variables. El prototipo seguirá una ruta confeccionada y transferida como un archivo de texto con un formato determinado que contendrá los datos necesarios para poder navegar mediante GPS. El trabajo con los modelos de motorización térmica (motores de combustión interna tipo glow, en este caso) resulta peligroso debido a la gran energía que son capaces de alcanzar. A fin de mantener la máxima seguridad durante la evolución del proyecto, se ha diseñado un proceso de tres partes independientes que permitan la correcta familiarización de los distintos componentes que se emplearán. Las fases son las siguientes: 1. Test y modelado de todos los componentes mediante pequeños montajes con protoboard de inserción y programas individuales. Se realizará mediante una tarjeta multipropósito que contendrá un microcontrolador similar en características, aunque de menor complejidad, al del prototipo final. 2. Integración de todos los componentes mediante una tarjeta especialmente diseñada que servirá de interfaz entre la tarjeta multipropósito y todo el hardware necesario para el control de un vehículo terrestre de iguales características (actuadores y motorización) al aeromodelo. 3. Diseño de un sistema embebido que concentre todos los subsistemas desarrollados en las fases anteriores y que integre todos los componentes necesarios para el gobierno de una aeronave de ala fija. ABSTRACT. Nowadays, the way of automating different tasks done by manned vehicles is studied. These tasks are any case very expensive, due to large fuel consumption, costs of aircraft buying, without taking into account the risk for human crew. As an example of these tasks, we can include policing or border surveillance, maintenance of high voltage lines, early warning of forest fire and measuring of pollution parameters. The target of this project is the design and construction of an embedded electronic prototype, based on a microcontroller with C8051 core from Silicon labs, and it will be able to controlling an aircraft transparently, in order that in the future the flying model could be changed with the modification of some parameters, and video or any variables detection systems could be added. The prototype will follow a designed and transferred path as an plain text file with a given format, that will contain all the necessary data for GPS navigation. Working with heat engine models (internal combustion engine, glow type, in this case) becomes dangerous due to the large energy that can be able to acquire. In order to keep the maximum safety level during the project evolution a three independent stages process have been designed, this allows familiarizing properly with the parts that will be used. The stages are as follows: 1. Test and modeling of all of the parts by little assemblies with through-hole protoboard and stand alone programs. It will be done with a multipurpose card which contains a microcontroller of similar characteristics, although less complex, of the final prototype. 2. Integrating of all of parts through a dedicated design card that will serve as interface between multipurpose card and all the necessary hardware for controlling a ground vehicle with the same characteristics (actuators and engine) of the flying model. 3. Embedded system designing that contains all the developed subsystems in the previous stages and integrates all the necessary parts for controlling a fixed-wing aircraft.

Soil compaction and vegetation cover in a Scots pine stand at the Mediterranean rangelands

Right development of ROOT SYSTEMS is essential to ensure seedling survival in the initial stages of natural regeneration processes. Soil compaction determines this development both because of its influence on soil Tª & moisture dynamics and for its direct effect on soil mechanical impedance to root growth. All this effects can be assessed as a whole through soil penetration resistance (Soil Strength) measurements. SOIL STRENGTH has been usually evaluated in forest research in connection with severe disturbances derived from heavy machinery works during forest operations. Nevertheless, undisturbed soils are also expected to show different levels of compaction for root development. Organic matter modifies soil structure and so on porosity, compaction and resultant soil resistance to penetration. Its concentration in surface layers is rather related to vegetation cover composition and density. So within forest stands, a relationship is expected to be found between VEGETATION COVER density and compaction measured as resistance to penetration (soil strength)

Local variability of serotinous cones in a Canary Island pine (Pinus canariensis) stand

The endemic Canary Island pine (Pinus canariensis) has an effective strategy to counteract fire disturbance in the short term. It has a mixed strategy that combines the presence of serotinous cones and thick barks with the ability to re-sprout from the trunk after a fire, a rare trait in pine species. High frequency of fires in the Canary Islands is related to human action, as natural fires by lightning or vulcan activity have very low frequency; hence, the how and whys of the presence of serotinous cones in the species is still a topic of debate. Previous studies showed that the frequency of serotinous cones varies from stand to stand. Here, we analyzed the presence of serotinous cones at a local scale. We selected a Canary Island pine stand in the transition zone between dry and humid forests in the south of Tenerife. Branches were pruned from 20 trees in order to evaluate the presence of serotinous vs. non-serotinous cones by direct verticile counting on the branches. The opening temperature of serotinous cones was assessed in the laboratory. Percentages of serotinous vs. non-serotinous cones varied from 0 to 93 %, showing high variability between trees. Opening temperatures were very high (above 65 ºC) as compared to other Mediterranean pine species with serotinous cones

Divided we stand: Parallel distributed stack memory management

We present an overview of the stack-based memory management techniques that we used in our non-deterministic and-parallel Prolog systems: &-Prolog and DASWAM. We believe that the problems associated with non-deterministic and-parallel systems are more general than those encountered in or-parallel and deterministic and-parallel systems, which can be seen as subsets of this more general case. We develop on the previously proposed "marker scheme", lifting some of the restrictions associated with the selection of goals while keeping (virtual) memory consumption down. We also review some of the other problems associated with the stack-based management scheme, such as handling of forward and backward execution, cut, and roll-backs.

Mixing effect on volume growth of Fagus sylvatica and Pinus sylvestris is modulated by stand density

Despite the increasing relevance of mixed stands due to their potential benefits; little information is available with regard to the effect of mixtures on yield in forest systems. Hence, it is necessary to study inter-specific relationships, and the resulting yield in mixed stands, which may vary with stand development, site or stand density, etc. In Spain, the province of Navarra is considered one of the biodiversity reservoirs; however, mixed forests occupy only a small area, probably as a consequence of management plans, in which there is an excessive focus on the productivity aspect, favoring the presence of pure stands of the most marketable species. The aim of this paper is to study how growth efficiencies of beech (Fagus sylvatica) and pine (Pinus sylvestris) are modified by the admixture of the other species and to determine whether stand density modifies interspecific relationships and to what extent. Two models were fitted from Spanish National Forest Inventory data, for P. sylvestris and F. sylvatica respectively, which relate the growth efficiency of the species, i.e. the volume increment of the species divided by the species proportion by area, with dominant height, quadratic mean diameter, stocking degree, and the species proportions by area of each species. Growth efficiency of pine increased with the admixture of beech, decreasing this positive effect when stocking degree increased. However, the positive effect of pine admixture on beech growth was greater at higher stocking degrees. Growth efficiency of beech was also dependent on stand dominant height, resulting in a net negative mixing effect when stand dominant heights and stocking degrees were simultaneously low. There is a relatively large range of species proportions and stocking degrees which results in transgressive overyielding: higher volume increments in mixed stands than that of the most productive pure pine stands. We concluded that stocking degree is a key factor in between-species interactions, being the effects of mixing not always greater at higher stand densities, but it depends on species composition.

Pibamarmi Stand, Verona (2009)

TRAPPING SUNLIGHT IN MOTION. The assignment was to design the stand for the prestigious Italian marble company Pibamarmi at the Marmocacc 2009 Fair = ATRAPAR LA LUZ DEL SOL EN MOVIMIENTO. Se trata de diseñar el pabellón para la prestigiosa empresa de mármoles italiana PIBAMARMI, en la Feria Marmomacc 2009.

Carbon dioxide emissions from semi-arid soils amended with biochar alone or combined with mineral and organic fertilizers

Semi-arid soils cover a significant area of Earth s land surface and typically contain large amounts of inorganic C. Determining the effects of biochar additions on CO2 emissions fromsemi-arid soils is therefore essential for evaluating the potential of biochar as a climate change mitigation strategy. Here, we measured the CO2 that evolved from semi-arid calcareous soils amended with biochar at rates of 0 and 20 t ha?1 in a full factorial combination with three different fertilizers (mineral fertilizer, municipal solid waste compost, and sewage sludge) applied at four rates (equivalent to 0, 75, 150, and 225 kg potentially available N ha?1) during 182 days of aerobic incubation. A double exponential model, which describes cumulative CO2 emissions from two active soil C compartments with different turnover rates (one relatively stable and the other more labile), was found to fit verywell all the experimental datasets. In general, the organic fertilizers increased the size and decomposition rate of the stable and labile soil C pools. In contrast, biochar addition had no effects on any of the double exponential model parameters and did not interact with the effects ascribed to the type and rate of fertilizer. After 182 days of incubation, soil organic and microbial biomass C contents tended to increase with increasing the application rates of organic fertilizer, especially of compost, whereas increasing the rate of mineral fertilizer tended to suppress microbial biomass. Biochar was found to increase both organic and inorganic C contents in soil and not to interactwith the effects of type and rate of fertilizer on C fractions. As a whole, our results suggest that the use of biochar as enhancer of semi-arid soils, either alone or combined with mineral and organic fertilizers, is unlikely to increase abiotic and biotic soil CO2 emissions.