Systematic Method to Assess Small-Signal Stability of DC-Distributed Power-System-Architecture

The objective of this paper is to present a simplified method to analyze small-signal stability of a power system and provide performance metrics for stability assessment of a given power-system-architecture. The stability margins are stated utilizing a concept of maximum peak criteria (MPC), derived from the behavior of an impedance-based sensitivity function that provides a single number to state the robustness of the stability of a well-defined minor-loop gain. For each minor-loop gain, defined at every system interface, the robustness of the stability is provided as a maximum value of the corresponding sensitivity function. Typically power systems comprise of various interfaces and, therefore, in order to compare different architecture solutions in terms of stability, a single number providing an overall measure of the whole system stability is required. The selected figure of merit is geometric average of each maximum peak value within the system, combined with the worst case value of system interfaces.

A semantic middleware architecture focused on data and heterogeneity management within the Smart Grid

There is an increasing tendency of turning the current power grid, essentially unaware of variations in electricity demand and scattered energy sources, into something capable of bringing a degree of intelligence by using tools strongly related to information and communication technologies, thus turning into the so-called Smart Grid. In fact, it could be considered that the Smart Grid is an extensive smart system that spreads throughout any area where power is required, providing a significant optimization in energy generation, storage and consumption. However, the information that must be treated to accomplish these tasks is challenging both in terms of complexity (semantic features, distributed systems, suitable hardware) and quantity (consumption data, generation data, forecasting functionalities, service reporting), since the different energy beneficiaries are prone to be heterogeneous, as the nature of their own activities is. This paper presents a proposal on how to deal with these issues by using a semantic middleware architecture that integrates different components focused on specific tasks, and how it is used to handle information at every level and satisfy end user requests.

A framework for goal-oriented discovery of resources in the RESTful architecture

One of the challenges facing the current web is the efficient use of all the available information. The Web 2.0 phenomenon has favored the creation of contents by average users, and thus the amount of information that can be found for diverse topics has grown exponentially in the last years. Initiatives such as linked data are helping to build the Semantic Web, in which a set of standards are proposed for the exchange of data among heterogeneous systems. However, these standards are sometimes not used, and there are still plenty of websites that require naive techniques to discover their contents and services. This paper proposes an integrated framework for content and service discovery and extraction. The framework is divided into several layers where the discovery of contents and services is made in a representational stateless transfer system such as the web. It employs several web mining techniques as well as feature-oriented modeling for the discovery of cross-cutting features in web resources. The framework is used in a scenario of electronic newspapers. An intelligent agent crawls the web for related news, and uses services and visits links automatically according to its goal. This scenario illustrates how the discovery is made at different levels and how the use of semantics helps implement an agent that performs high-level tasks.

Climatic analysis methodology of vernacular architecture

Vernacular architecture has demonstrated its perfect environmental adaptation through its empirical development and improvement by generations of user-builders. Nowadays, the sustainability of vernacular architecture is the aim of some research projects in which the same method should be applied in order to be comparable. Hence, we propose a research method putting together various steps. Through the analysis of geographical, lithology, economic, cultural and social influence as well as materials and constructive systems, vernacular architecture is analyzed. But, all this information is put together with the natural landscape (topography and vegetation) and the climatic data (temperature, winds, rain and sun exposure). In addition, the use of bioclimatic charts, such as Olgyay or Givoni’s, revealed the necessities and strategies in urban and building design. They are satisfied in the vernacular architecture by the application of different energy conservation mechanisms, some of them are shown by different examples in this paper.

Modelling spatial decisión support systems focused on the development of a data warehouse: applying software engineering

Nowadays, organizations have plenty of data stored in DB databases, which contain invaluable information. Decision Support Systems DSS provide the support needed to manage this information and planning médium and long-term ?the modus operandi? of these organizations. Despite the growing importance of these systems, most proposals do not include its total evelopment, mostly limiting itself on the development of isolated parts, which often have serious integration problems. Hence, methodologies that include models and processes that consider every factor are necessary. This paper will try to fill this void as it proposes an approach for developing spatial DSS driven by the development of their associated Data Warehouse DW, without forgetting its other components. To the end of framing the proposal different Engineering Software focus (The Software Engineering Process and Model Driven Architecture) are used, and coupling with the DB development methodology, (and both of them adapted to DW peculiarities). Finally, an example illustrates the proposal.

MAIA: an event-based modular architecture for intelligent agents

Online services are no longer isolated. The release of public APIs and technologies such as web hooks are allowing users and developers to access their information easily. Intelligent agents could use this information to provide a better user experience across services, connecting services with smart automatic. behaviours or actions. However, agent platforms are not prepared to easily add external sources such as web services, which hinders the usage of agents in the so-called Evented or Live Web. As a solution, this paper introduces an event-based architecture for agent systems, in accordance with the new tendencies in web programming. In particular, it is focused on personal agents that interact with several web services. With this architecture, called MAIA, connecting to new web services does not involve any modification in the platform.

The historical heritage of domestic architecture is a reliable model for a satisfactory design. The case of the Mediterranean region

The purpose of this paper is to expose the importance of observing cultural systems present in a territory as a reference for the design of urban infrastructures in the new cities and regions of rapid development. If we accept the idea that architecture is an instrument or cultural system developed by man to act as an intermediary to the environment, it is necessary to understand the elemental interaction between man and his environment to meet a satisfactory design. To illustrate this purpose, we present the case of the Eurasian Mediterranean region, where the architectural culture acts as a cultural system of adaptation to the environment and it is formed by an ancient process of selection. From simple observation of architectural types, construction systems and environmental mechanisms treasured in mediterranean historical heritage we can extract crucial information about this elemental interaction. Mediterranean architectural culture has environmental mechanisms responding to the needs of basics habitability, ethnics and passive conditioning. These mechanisms can be basis of an innovative design without compromising the diversity and lifestyles of human groups in the region. The main fundament of our investigation is the determination of the historical heritage of domestic architecture as holder of the formation process of these mechanisms. The result allows us to affirm that the successful introduction of new urban infrastructures in an area need a reliable reference and it must be a cultural system that entailing in essence the environmental conditioning of human existence. The urban infrastructures must be sustainable, understood and accepted by the inhabitants. The last condition is more important when the urban infrastructures are implemented in areas that are developing rapidly or when there is no architectural culture.

Performance evaluation of database replication systems.

One of the most demanding needs in cloud computing is that of having scalable and highly available databases. One of the ways to attend these needs is to leverage the scalable replication techniques developed in the last decade. These techniques allow increasing both the availability and scalability of databases. Many replication protocols have been proposed during the last decade. The main research challenge was how to scale under the eager replication model, the one that provides consistency across replicas. In this paper, we examine three eager database replication systems available today: Middle-R, C-JDBC and MySQL Cluster using TPC-W benchmark. We analyze their architecture, replication protocols and compare the performance both in the absence of failures and when there are failures.

Evolving a core Banking enterprise architecture: leveraging business events exploitation

Business information has become a critical asset for companies and it has even more value when obtained and exploited in real time. This paper analyses how to integrate this information into an existing banking Enterprise Architecture, following an event-driven approach, and entails the study of three main issues: the definition of business events, the specification of a reference architecture, which identifies the specific integration points, and the description of a governance approach to manage the new elements. All the proposed solutions have been validated with a proof-of-concept test bed in an open source environment. It is based on a case study of the banking sector that allows an operational validation to be carried out, as well as ensuring compliance with non-functional requirements. We have focused these requirements on performance.

Emergency management in the highways of the future. A performance-based multilayered ITS architecture design proposal

Emergency management is one of the key aspects within the day-to-day operation procedures in a highway. Efficiency in the overall response in case of an incident is paramount in reducing the consequences of any incident. However, the approach of highway operators to the issue of incident management is still usually far from a systematic, standardized way. This paper attempts to address the issue and provide several hints on why this happens, and a proposal on how the situation could be overcome. An introduction to a performance based approach to a general system specification will be described, and then applied to a particular road emergency management task. A real testbed has been implemented to show the validity of the proposed approach. Ad-hoc sensors (one camera and one laser scanner) were efficiently deployed to acquire data, and advanced fusion techniques applied at the processing stage to reach the specific user requirements in terms of functionality, flexibility and accuracy.

Memory isolation in many-core embedded systems

The current approach to developing mixed-criticality sys- tems is by partitioning the hardware resources (processors, memory and I/O devices) among the different applications. Partitions are isolated from each other both in the temporal and the spatial domain, so that low-criticality applications cannot compromise other applications with a higher level of criticality in case of misbehaviour. New architectures based on many-core processors open the way to highly parallel systems in which each partition can be allocated to a set of dedicated proces- sor cores, thus simplifying partition scheduling and temporal separation. Moreover, spatial isolation can also benefit from many-core architectures, by using simpler hardware mechanisms to protect the address spaces of different applications. This paper describes an architecture for many- core embedded partitioned systems, together with some implementation advice for spatial isolation.

Cooperative ITS communications architecture: the FOTsis project approach and beyond

With the continuous development in the fields of sensors, advanced data processing and communications, road transport oriented intelligent applications and services have reached a significant maturity and complexity. Cooperative ITS services, based on the idea of sharing accurate information among road entities, are currently being tested on a large scale by different initiatives. The field operational test (FOTsis) project contributes to the deployment environment with services that involve a significant number of entities out of the vehicle. This made necessary the specification of an architecture which, based on the ISO ITS station reference architecture for communications, could support the requirements of the services proposed in the project. During the project, internal implementation tests and external interoperability tests have resulted in the validation of the proposed architecture. At the same time, these tests have had as a result the awareness of areas in which the FOTsis architecture could be completed, mainly to take full advantage of all the emerging and foreseeable data sources which may be relevant in the road environment. In this study, the authors will outline an approach that, based on the current cooperative ITS architecture and the SmartCities and Internet Of Things (IoT) architectures, can provide a common convergence platform to maximise the information available for ITS purposes.

High brightness semiconductor lasers as transmitters for space lidar systems

High brightness semiconductor lasers are potential transmitters for future space lidar systems. In the framework of the European Project BRITESPACE, we propose an all-semiconductor laser source for an Integrated Path Differential Absorption lidar system for column-averaged measurements of atmospheric CO2 in future satellite missions. The complete system architecture has to be adapted to the particular emission properties of these devices using a Random Modulated Continuous Wave approach. We present the initial experimental results of the InGaAsP/InP monolithic Master Oscillator Power Amplifiers, providing the ON and OFF wavelengths close to the selected absorption line around 1572 nm.

Fault management techniques for systems with SRAM-based FPGAs

Las Field-Programmable Gate Arrays (FPGAs) SRAM se construyen sobre una memoria de configuración de tecnología RAM Estática (SRAM). Presentan múltiples características que las hacen muy interesantes para diseñar sistemas empotrados complejos. En primer lugar presentan un coste no-recurrente de ingeniería (NRE) bajo, ya que los elementos lógicos y de enrutado están pre-implementados (el diseño de usuario define su conexionado). También, a diferencia de otras tecnologías de FPGA, pueden ser reconfiguradas (incluso en campo) un número ilimitado de veces. Es más, las FPGAs SRAM de Xilinx soportan Reconfiguración Parcial Dinámica (DPR), la cual permite reconfigurar la FPGA sin interrumpir la aplicación. Finalmente, presentan una alta densidad de lógica, una alta capacidad de procesamiento y un rico juego de macro-bloques. Sin embargo, un inconveniente de esta tecnología es su susceptibilidad a la radiación ionizante, la cual aumenta con el grado de integración (geometrías más pequeñas, menores tensiones y mayores frecuencias). Esta es una precupación de primer nivel para aplicaciones en entornos altamente radiativos y con requisitos de alta confiabilidad. Este fenómeno conlleva una degradación a largo plazo y también puede inducir fallos instantáneos, los cuales pueden ser reversibles o producir daños irreversibles. En las FPGAs SRAM, los fallos inducidos por radiación pueden aparecer en en dos capas de arquitectura diferentes, que están físicamente superpuestas en el dado de silicio. La Capa de Aplicación (o A-Layer) contiene el hardware definido por el usuario, y la Capa de Configuración contiene la memoria de configuración y la circuitería de soporte. Los fallos en cualquiera de estas capas pueden hacer fracasar el sistema, lo cual puede ser ás o menos tolerable dependiendo de los requisitos de confiabilidad del sistema. En el caso general, estos fallos deben gestionados de alguna manera. Esta tesis trata sobre la gestión de fallos en FPGAs SRAM a nivel de sistema, en el contexto de sistemas empotrados autónomos y confiables operando en un entorno radiativo. La tesis se centra principalmente en aplicaciones espaciales, pero los mismos principios pueden aplicarse a aplicaciones terrenas. Las principales diferencias entre ambas son el nivel de radiación y la posibilidad de mantenimiento. Las diferentes técnicas para la gestión de fallos en A-Layer y C-Layer son clasificados, y sus implicaciones en la confiabilidad del sistema son analizados. Se proponen varias arquitecturas tanto para Gestores de Fallos de una capa como de doble-capa. Para estos últimos se propone una arquitectura novedosa, flexible y versátil. Gestiona las dos capas concurrentemente de manera coordinada, y permite equilibrar el nivel de redundancia y la confiabilidad. Con el objeto de validar técnicas de gestión de fallos dinámicas, se desarrollan dos diferentes soluciones. La primera es un entorno de simulación para Gestores de Fallos de C-Layer, basado en SystemC como lenguaje de modelado y como simulador basado en eventos. Este entorno y su metodología asociada permite explorar el espacio de diseño del Gestor de Fallos, desacoplando su diseño del desarrollo de la FPGA objetivo. El entorno incluye modelos tanto para la C-Layer de la FPGA como para el Gestor de Fallos, los cuales pueden interactuar a diferentes niveles de abstracción (a nivel de configuration frames y a nivel físico JTAG o SelectMAP). El entorno es configurable, escalable y versátil, e incluye capacidades de inyección de fallos. Los resultados de simulación para algunos escenarios son presentados y comentados. La segunda es una plataforma de validación para Gestores de Fallos de FPGAs Xilinx Virtex. La plataforma hardware aloja tres Módulos de FPGA Xilinx Virtex-4 FX12 y dos Módulos de Unidad de Microcontrolador (MCUs) de 32-bits de propósito general. Los Módulos MCU permiten prototipar Gestores de Fallos de C-Layer y A-Layer basados en software. Cada Módulo FPGA implementa un enlace de A-Layer Ethernet (a través de un switch Ethernet) con uno de los Módulos MCU, y un enlace de C-Layer JTAG con el otro. Además, ambos Módulos MCU intercambian comandos y datos a través de un enlace interno tipo UART. Al igual que para el entorno de simulación, se incluyen capacidades de inyección de fallos. Los resultados de pruebas para algunos escenarios son también presentados y comentados. En resumen, esta tesis cubre el proceso completo desde la descripción de los fallos FPGAs SRAM inducidos por radiación, pasando por la identificación y clasificación de técnicas de gestión de fallos, y por la propuesta de arquitecturas de Gestores de Fallos, para finalmente validarlas por simulación y pruebas. El trabajo futuro está relacionado sobre todo con la implementación de Gestores de Fallos de Sistema endurecidos para radiación. ABSTRACT SRAM-based Field-Programmable Gate Arrays (FPGAs) are built on Static RAM (SRAM) technology configuration memory. They present a number of features that make them very convenient for building complex embedded systems. First of all, they benefit from low Non-Recurrent Engineering (NRE) costs, as the logic and routing elements are pre-implemented (user design defines their connection). Also, as opposed to other FPGA technologies, they can be reconfigured (even in the field) an unlimited number of times. Moreover, Xilinx SRAM-based FPGAs feature Dynamic Partial Reconfiguration (DPR), which allows to partially reconfigure the FPGA without disrupting de application. Finally, they feature a high logic density, high processing capability and a rich set of hard macros. However, one limitation of this technology is its susceptibility to ionizing radiation, which increases with technology scaling (smaller geometries, lower voltages and higher frequencies). This is a first order concern for applications in harsh radiation environments and requiring high dependability. Ionizing radiation leads to long term degradation as well as instantaneous faults, which can in turn be reversible or produce irreversible damage. In SRAM-based FPGAs, radiation-induced faults can appear at two architectural layers, which are physically overlaid on the silicon die. The Application Layer (or A-Layer) contains the user-defined hardware, and the Configuration Layer (or C-Layer) contains the (volatile) configuration memory and its support circuitry. Faults at either layers can imply a system failure, which may be more ore less tolerated depending on the dependability requirements. In the general case, such faults must be managed in some way. This thesis is about managing SRAM-based FPGA faults at system level, in the context of autonomous and dependable embedded systems operating in a radiative environment. The focus is mainly on space applications, but the same principles can be applied to ground applications. The main differences between them are the radiation level and the possibility for maintenance. The different techniques for A-Layer and C-Layer fault management are classified and their implications in system dependability are assessed. Several architectures are proposed, both for single-layer and dual-layer Fault Managers. For the latter, a novel, flexible and versatile architecture is proposed. It manages both layers concurrently in a coordinated way, and allows balancing redundancy level and dependability. For the purpose of validating dynamic fault management techniques, two different solutions are developed. The first one is a simulation framework for C-Layer Fault Managers, based on SystemC as modeling language and event-driven simulator. This framework and its associated methodology allows exploring the Fault Manager design space, decoupling its design from the target FPGA development. The framework includes models for both the FPGA C-Layer and for the Fault Manager, which can interact at different abstraction levels (at configuration frame level and at JTAG or SelectMAP physical level). The framework is configurable, scalable and versatile, and includes fault injection capabilities. Simulation results for some scenarios are presented and discussed. The second one is a validation platform for Xilinx Virtex FPGA Fault Managers. The platform hosts three Xilinx Virtex-4 FX12 FPGA Modules and two general-purpose 32-bit Microcontroller Unit (MCU) Modules. The MCU Modules allow prototyping software-based CLayer and A-Layer Fault Managers. Each FPGA Module implements one A-Layer Ethernet link (through an Ethernet switch) with one of the MCU Modules, and one C-Layer JTAG link with the other. In addition, both MCU Modules exchange commands and data over an internal UART link. Similarly to the simulation framework, fault injection capabilities are implemented. Test results for some scenarios are also presented and discussed. In summary, this thesis covers the whole process from describing the problem of radiationinduced faults in SRAM-based FPGAs, then identifying and classifying fault management techniques, then proposing Fault Manager architectures and finally validating them by simulation and test. The proposed future work is mainly related to the implementation of radiation-hardened System Fault Managers.

Feo, inútil, inestable: pensamiento crítico contemporáneo y procesos proyectivos en arquitectura = Ugly, useless, unstable: contemporary critical thought and projective processes in architecture

La presente tesis doctoral persigue dos objetivos simultáneos: Determinar el alcance de los criterios clásicos para la evaluación de arquitectura y poner en crisis la prevalencia de esos mismos criterios dentro del marco crítico y productivo actual. En concreto, esta tesis se interroga sobre la posible contribución de determinadas corrientes del pensamiento post-estructuralista y neo-materialista a las tareas de expansión y transformación de los criterios clásicos antes mencionados. Asimismo, se plantea la oportunidad de formalizar estas incorporaciones conceptuales como metodologías para el proyectar arquitectónico. La tesis emplea un análisis pormenorizado de las cualidades implícitas en la triada Firmitas, Utilitas, Venustas elaborada por Vitruvio como vehículo para calibrar la influencia de los paradigmas de pensamiento clásico en nuestras posiciones críticas contemporáneas. Como reacción al carácter dominante de dichos paradigmas, y con la ayuda de una compilación selectiva de ejemplos procedentes de los campos artístico y arquitectónico, la presente tesis procede a examinar y clasificar diversas estrategias arquitectónicas basadas en la no conformidad con los criterios clásicos de evaluación de la disciplina. A la hora de realizar esta tarea, y con el objetivo de superar el dualismo trascendental que caracteriza la gran mayoría de dichos criterios clásicos, se propone un modelo analítico y multidimensional que formula las instancias arquitectónicas como posibles posiciones dentro de un extenso continuo combinatorio de cualidades formales, estructurales y organizativas. Este modelo conceptual permite replantear el aparente antagonismo entre los principios de Vitruvio y sus opuestos, estableciendo en su lugar un dominio operativo continuo de producción arquitectónica. Esta operación abre una ventana de oportunidad para expandir los límites del marco crítico actual más allá de las fronteras establecidas por nuestra herencia clásica. En consecuencia con esta voluntad, la presente tesis pretende habilitar un ámbito para el análisis crítico de las estrategias que caracterizan ciertas corrientes del proyectar contemporáneo, pero también contribuir a informar nuevas aproximaciones metodológicas al proceso de proyecto, desplazando progresivamente su foco desde lo descriptivo hacia lo proyectivo. ABSTRACT This doctoral thesis attempts to simultaneously determine the scope of the classical criteria for the evaluation of architecture and challenge their prevalence within the current framework of architectural production and criticism. It examines how specific strands of post-structuralism and neo-materialism may contribute to both the expansion and the transformation of these criteria and, in doing so, sets itself the goal of mobilising these conceptual incorporations as explicit design methodologies. A detailed analysis of the formal, structural and organisational qualities implicit in Vitruvius’ triad Firmitas, Utilitas, Venustas is used as a starting point to determine the influence of classical paradigms in our current critical positions. As a reaction to this critical pervasiveness, and supported by a curated collection of artistic and architectural works, diverse approaches to non-compliance with the classical criteria of assessment are examined and classified. In order to facilitate this endeavour -and to overcome the transcendental dualism of most classical critical approaches in architecture- this thesis puts forward an analytical, multidimensional model that formulates architectural instances as possible positions within a larger combinatory continuum of formal, structural and organisational qualities. Using this conceptual model, the apparent antagonism between Vitruvius’ principles and its non-compliant opposites is reframed as a continuous operative domain of architectural production, which in turn opens up a window of opportunity to expand the limits of our critical framework beyond the boundaries of classical paradigms. In doing so, this thesis attempts not only to foster a better understanding of some of the strategic approaches that characterise contemporary systems of architectural production, but also to inform future methodological approaches to architectural design, hence situating itself beyond the domain of the descriptive and moving towards the projective.