36 research outputs found

    Flexible Real-Time Linux a New Environment for Flexible Hard Real-Time Systems

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    [ES] La presente tesis propone un nuevo entorno general para la construcción de sistemas flexibles de tiempo real estricto, esto es, sistemas que necesitan de garantías de tiempo real estricto y de un comportamiento flexible. El entorno propuesto es capaz de integrar tareas con varios niveles de criticidad y diferentes paradigmas de planificación en el mismo sistema. Como resultado, el entorno permite proporcionar garantías de tiempo real estricto a las tareas críticas y además conseguir una planificación adaptativa e inteligente de las tareas menos críticas. El entorno se define en términos de un modelo de tareas, una arquitectura software y un conjunto de servicios. El modelo de tareas propone construir una aplicación flexible de tiempo real estricto como un conjunto de tareas, donde cada tarea se estructura en una secuencia de componentes obligatorios y opcionales. La arquitectura software propone separar la ejecución de las tareas en dos niveles de planificación interrelacionados, de manera que un nivel planifica los componentes obligatorios mediante una política de planificación de tiempo real estricto mientras que el otro nivel planifica los componentes opcionales mediante una política de planificación basada en la utilidad. El conjunto de servicios incluye, por una parte, un sistema de comunicación entre los componentes de las tareas (tanto obligatorios como opcionales) y, por otra, una serie de mecanismos para la detección y tratamiento de excepciones temporales producidas en ejecución. Por otra parte, la presente tesis muestra que el entorno teórico propuesto puede ser implementado realmente. En concreto, se presenta el diseño e implementación de un sistema de ejecución (es decir, un núcleo de sistema operativo) capaz de soportar las características de dicho entorno. Este sistema, denominado Flexible Real-Time Linux (FRTL), ha sido desarrollado a partir de un núcleo mínimo existente denominado Real-Time Linux (RT-Linux). Finalmente, esta tesis presenta una caracterización temporal completa del sistema FRTL y medidas reales de su sobrecarga. La caracterización temporal ha permitido el desarrollo de un test de garantía completo de todo el sistema (incluyendo la aplicación y el núcleo de FRTL), que puede ser utilizado para verificar las restricciones temporales de cualquier aplicación implementada sobre FRTL. Por su parte, las medidas de la sobrecarga de FRTL muestran que este núcleo ha sido diseñado e implementado de manera eficiente. En conjunto, se demuestra que el núcleo FRTL es a la vez predecible y eficiente, dos características que informan de su utilidad en la implementación real de aplicaciones flexibles de tiempo real estricto.[CA] Aquesta tesi proposa un nou entorn general per a la construcció de sistemes flexibles de temps real estricte, això és, sistemes que requereixen garanties de temps real estricte i un comportament flexible. L'entorn proposat és capaç d'integrar tasques amb diferentsnivells de criticitat i diferents paradigmes de planificació al mateix sistema. Com a resultat, l'entorn permet proporcionar garanties detemps real estricte a les tasques crítiques i a més aconseguir una planificació adaptativa i intel¿ligent de les tasques menys crítiques. L'entorn es defineix en termes d'un model de tasques, una arquitectura software i un conjunt de serveis. El model de tasques proposa la construcció d'una aplicació flexible de temps real estricte com a un conjunt de tasques on cadascuna és estructurada com una seqüència de components obligatòries i opcionals. L'arquitectura software proposa la separació de l'execució de les tasques en dos nivells de planificació interrelacionats, de manera que un nivel planifica les components obligatòries mitjançant una política de planificació de temps real estricte mentre que l'altre nivell planifica les components opcionals mitjançant una política de planificació basada en la utilitat. El conjunt de serveis inclou, per una part, un sistema de comunicació entre les components de les tasques (tant obligatòries com opcionals) i, per una altra, una sèrie de mecanismes per a la detecció i tractament d'excepcions temporals produïdes en execució. Per altra banda, la present tesi mostra que el proposat entorn teòric pot ésser implementat realment. En concret, es presenta el diseny i la implementació d'un sistema d'execució (es a dir, un nucli de sistema operatiu) capaç de suportar les característiques d'aquest entorn. Aquest sistema, anomenat Flexible Real-Time Linux (FRTL), ha sigut desenvolupat a partir d'un nucli mínim existent anomenat Real-Time Linux (RT-Linux). Finalment, aquesta tesi presenta una caracterització temporal completa del sistema FRTL i mesures reals de la seua sobrecàrrega. La caracterització temporal ha permés el desenvolupament d'un test de garantia complet de tot el sistema (incloent l'aplicació i el nucli FRTL), que pot ésser utilitzat per a verificar les restriccions temporals de qualsevol aplicació implementada sobre FRTL. Per la seua part, les mesures de la sobrecàrrega de FRTL mostren que aquest nucli ha sigut disenyat i implementat de manera eficient. En conjunt, es demostra que el nucli FRTL és al mateix temps predible i eficient, dos característiques que informen de la seua utilitat a la implementació real d'aplicacions flexibles de temps real estricte.Terrasa Barrena, AM. (2001). Flexible Real-Time Linux a New Environment for Flexible Hard Real-Time Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1806

    An evaluation and comparison of PLC programming techniques : innovation report

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    Few significant changes in Programmable Logic Controller (PLC) software design techniques have taken place since PLC's were first introduced in the 1960's. Programs written in the traditional language used in PLC's, ladder logic, are generally thought to be difficult to maintain and modify, and thus ill suited to the support of modem flexible manufacturing processes. This work demonstrates that the choice of PLC software structure used in a project has an impact on process flexibility with an appropriate choice providing significant cost savings in development time. An overview of work on formalised programming tools conducted in academia is provided together with a report on the PLC software structures used in industry. The factors influencing the choice of PLC and software structure are identified. Familiarity was found to be a major factor influencing selection. A method for comparing code structures, which allows the results to be expressed as a time saving (and consequently a cost) has been created. Implementation of this approach was used to show that the formalised programming tool under test provides a 33% increase in "right first time" rate together with an 80% time saving over traditional contact based ladder logic. Among experienced practitioners, performance with step-based ladder logic was found to be a close match to the formalised tool, demonstrating that the commonly perceived limitations are the result of the structure in which the language is used rather than a function of the programming tool itself. Further investigation of participant preferences among skilled PLC users showed a mismatch between their performance with a tool and their preference, with at least 25% selecting a tool based on their prior knowledge rather than performance. This highlights the need for the use of objective measures when conducting evaluations between products and technologies. With the information provided in this work, automation end users are provided with a mechanism for ensuring the selection of automation tools best suited to their business needs, whilst at the same time providing automation vendors with the ability to best demonstrate the strengths of the products

    Reusable Rocket Engine Operability Modeling and Analysis

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    This paper describes the methodology, model, input data, and analysis results of a reusable launch vehicle engine operability study conducted with the goal of supporting design from an operations perspective. Paralleling performance analyses in schedule and method, this requires the use of metrics in a validated operations model useful for design, sensitivity, and trade studies. Operations analysis in this view is one of several design functions. An operations concept was developed given an engine concept and the predicted operations and maintenance processes incorporated into simulation models. Historical operations data at a level of detail suitable to model objectives were collected, analyzed, and formatted for use with the models, the simulations were run, and results collected and presented. The input data used included scheduled and unscheduled timeline and resource information collected into a Space Transportation System (STS) Space Shuttle Main Engine (SSME) historical launch operations database. Results reflect upon the importance not only of reliable hardware but upon operations and corrective maintenance process improvements

    Iodine Status in Pregnant & Breastfeeding Women:A Danish Regional Investigation

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    Understanding the developmental basis of grain yield potential in bread wheat

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    Grain yield potential in wheat is a complex trait controlled by sub-traits like grain number, grain size, and assimilate partitioning. To achieve further understanding of grain yield potential, this thesis combines physiological and genetic dissection of wheat development. In particular, how the length of developmental phases can be optimized in favour of increased partitioning of assimilates to the spike, in order to reduce abortion rates of florets. The physiological section of the thesis (Chapter 2 and 3) comprises the in depth study of the CIMCOG panel (CIMMYT Core Germplasm). In this section the variation in patterns of floret and phenological development was determined, ascertaining how these differences affect the number of fertile florets. The differences in floret development were clear in the intermediate florets (floret primordia 3, 4, and 5 from the rachis). Floret survival was found to be positively related to the length of the period of floret development. Also fruiting efficiency, using the frontier concept, show a positive relationship with the stem elongation period. The genetic section (Chapter 4 and 5) involves the use of quantitative trait locus (QTL) analysis with a segregating population to determine the chromosomal locations affecting key developmental traits. A Buster x Charger doubled haploid population provided a crucial contrast between similar genetic background and differences in length of phenological phases. The results show that a QTL on chromosome 7A has an effect on the time to terminal spikelet phase, i.e. the onset of stem elongation, and QTL affecting time to heading was found on chromosomes 2D and 4A. Furthermore, this population also varies in lodging resistance. A major QTL was found on chromosome 2D affecting height and providing lodging resistance. These studies provide the basis to optimise wheat developmental patterns and, therefore, maximize spike fertility

    Analysis of Cell Signaling Perturbations in Response to Chronic Localized Infections

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    The tissue-level response to pathogens involves an intricate series of signal transduction events, influenced by immune and healing mediators that alert the host to danger and eliminate the infection. Disruptions to normal signaling events can compromise the host’s ability to respond and lead to the development of chronic infections that cannot be resolved without clinical intervention. Prolonged inflammation due to chronic infection can damage tissues and compromise healing processes, thus, the interactions of immune and healing mediators in signaling cascades are intimately linked to tissue health outcomes. Studying signaling networks relevant to these responses provided a more thorough understanding of localized tissue health to identify the drivers of disruptions to signaling cascades, and this knowledge can lead to the development of improved diagnostic and therapeutic biomarkers to combat chronic infections. The work presented here focused on elucidating the relationships between immune and wound healing factors in an in vivo rodent model and a clinical cohort to understand the tissue-level responses to chronic inflammation and infection. Specifically, extracellular inflammatory immune responses (i.e., cytokines and chemokines) related to intracellular signaling (i.e., phosphorylation of proteins) were investigated to identify alterations in native responses compared to those provoked by chronic inflammation and infection. Reponses in native tissues were compared to tissues with inflammatory and infectious stimuli to test if levels of immune related cytokines were elevated in response to chronic joint infections. Wound healing phosphoproteins were also included to look for shifts in wound healing-related processes across groups. Traditional statistical approaches and network analysis were used to dissect these complex biological datasets and identified drivers of network disruptions in response to inflammation and infection. The spatial analysis suggested that changes in biological responses were related to proximity to inflammation and infection, and the degree of response differed across spatial gradients, which demonstrated the ability for these chronic insults to affect disparate tissues in a clinically-relevant manner. The objective of this research and future related research is to facilitate new clinical strategies to combat chronic infection, and monitoring alterations to cell signaling pathways in this work highlighted the value of using network analysis to approach biological interrogation of signal disruptions related to these insults

    Verification of the C0 compiler implementation on the source code level

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    This thesis concerns practical application of two methods for program verification. The programming language we consider is a C dialect, called C0, which supports dynamic memory allocation, recursion, pointer types, etc. First, we verify a program using a formalization of small-step semantics of C0. The example we study is a small loop program, which allocates a linked list of the given length on the heap. Second, we describe the verification of a compiler implementation in a Hoare Logic in the sense of partial correctness. The source and implementation language of the compiler is C0. The correctness statement is divided into independent parts: i) the correctness of the compilation algorithm with respect to the target machine and ii) the correctness of the implementation with respect to the specified algorithm. This thesis considers the second task. We give the formal specification of the compilation algorithm and develop the connection of the implementation data structures to the abstract types used in the specification. Finally, we show the correctness of the compiler implementation with respect to the specification.Die vorliegende Arbeit befasst sich mit der praktischen Anwendung von zwei Methoden zur Programmverifikation. Die Programmiersprache, die dabei betrachtet wird, ist C0, ein C Dialekt, der unter anderem dynamische Allokation von Speicher, Rekursion und Pointer unterstützt. Zuerst beweisen wir die Korrektheit eines Programms mit Hilfe der formalen Small-Step Semantik von C0. Das Beispiel, das wir untersuchen, ist ein kleines Programm, das in einer Schleife eine gelinkte Liste gegebener Länge auf dem Heap alloziert. Danach beschreiben wir die Verifikation einer Compiler-Implementierung mittels einer Hoare Logik für partielle Korrektheit. Die Quell- und Implementierungssprache des Compilers ist C0. Die Korrektheitsaussage ist in unabhängige Aufgaben aufgeteilt: i) die Korrektheit des Compileralgorithmus bezüglich der Zielarchitektur und ii) die Korrektheit der Implementierung bezüglich dieses Algorithmus. Die vorliegende Arbeit beschäftigt sich mit der zweiten Aufgabe. Wir beschreiben die formale Spezifikation des Compileralgorithmus und entwickeln eine Verbindung zwischen den Datenstrukturen der Implementierung und den abstrakten Typen, die in der Spezifikation benutzt werden. Schließlich zeigen wir die Korrektheit der Compilerimplementierung bezüglich der Spezifikation

    Thyroid Hormone

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    Thyroid hormone is important for controlling metabolism and many other body functions. Changes in thyroid hormone physiology, its regulation and diseases thereof have been a concern for the mankind. Understanding of the thyroid hormone(s) has been continuously updated and revised. The contributions from different authors have been incorporated in this book for this purpose. The original work of these contributors will be especially useful in furthering the knowledge on thyroid and help in creating new vistas of research
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