Fault Tolerance Analysis and Self-Healing Strategy of Autonomous, Evolvable Hardware Systems

This paper presents an analysis of the fault tolerance achieved by an autonomous, fully embedded evolvable hardware system, which uses a combination of partial dynamic reconfiguration and an evolutionary algorithm (EA). It demonstrates that the system may self-recover from both transient and cumulative permanent faults. This self-adaptive system, based on a 2D array of 16 (4×4) Processing Elements (PEs), is tested with an image filtering application. Results show that it may properly recover from faults in up to 3 PEs, that is, more than 18% cumulative permanent faults. Two fault models are used for testing purposes, at PE and CLB levels. Two self-healing strategies are also introduced, depending on whether fault diagnosis is available or not. They are based on scrubbing, fitness evaluation, dynamic partial reconfiguration and in-system evolutionary adaptation. Since most of these adaptability features are already available on the system for its normal operation, resource cost for self-healing is very low (only some code additions in the internal microprocessor core)

Comparative Analysis of Tolerances Allocation in Mechanical Assemblies based on Cost-tolerance Curves

El presente trabajo propone un método para la determinación de los valores de las tolerancias individuales de las piezas que forman un conjunto ensamblado a partir de valores de tolerancias especificados en el conjunto final, optimizando el coste total de fabricación de las piezas individuales a partir de funciones de coste-tolerancia basadas en el proceso de fabricación de cada una de ellas. Para ello se parte de los principales trabajos desarrollados en la línea de asignación de tolerancias y se realiza la propuesta del modelo de trabajo, basado en la optimización de costes a partir de la aplicación del método de los multiplicadores de Lagrange a diversas curvas de coste-tolerancia

Caracterización molecular del mutante riso 1508 de cebada : modificaciones transcripcionales y posttranscripcionales en el desarrollo de la semilla

La semilla es el principal órgano reproductivo de las plantas espermatofitas, permitiendo la dispersión de las poblaciones y asegurando su supervivencia gracias a su tolerancia a la desecación y a su capacidad para germinar bajo condiciones ambientales óptimas. El rendimiento y valor económico de los cereales, que constituyen la primera cosecha mundial, depende, en buena medida, de la eficacia con que se acumulan en la semilla sustancias de reserva: proteínas, carbohidratos y lípidos. El principal carbohidrato acumulado en la semilla de cebada es el almidón y la fracción mayoritaria de proteínas es la de las prolaminas (solubles en etanol al 70%); estas proteínas tienen muy bajo contenido en lisina, un aminoácido esencial en la dieta de animales monogástricos. Con el fin de mejorar el valor nutricional de la semilla de cebada, se han obtenido diferentes mutantes con un mayor contenido en este aminoácido. Riso 1508 es un mutante de cebada rico en lisina cuya mutación lys3a, de efectos pleiotrópicos, segrega como un único gen mendeliano. Entre otros, presenta una reducción drástica de la expresión de algunos genes que codifican proteínas de reserva de tipo prolamina, en concreto, presenta reducida la expresión de los genes que codifican B-, C- y ϒ-Hordeínas y del inhibidor de tripsina CMe, pero no tiene alterada la expresión del gen que codifica las D-Hordeínas. Este último gen carece en su promotor del motivo GLM (5’‐(G/A)TGA(G/C)TCA(T/C)‐3’), que es reconocido por factores transcripcionales bZIP. En este trabajo, el mutante de cebada Riso 1508 se ha utilizado como herramienta para profundizar en el conocimiento de la regulación génica en semillas durante las fases de la maduración y la germinación. Para ello, en una primera aproximación, se llevó a cabo un análisis transcriptómico comparando el genotipo mutante con el silvestre durante la maduración de la semilla. Además de confirmar variaciones en los genes que codifican proteínas de reserva, este análisis indicó que también estaban afectados los genes relacionados con metabolismo de carbohidratos. Por ello se decidió caracterizar la familia multigénica de sacarosas sintasa (SUSy) en cebada. Se anotaron dos nuevos genes, HvSs3 y HvSs4, cuya expresión se comparó con la de los genes HvSs1 y HvSs2, previamente descritos en el laboratorio. La expresión de los cuatro genes en tejidos diferentes y su respuesta a estreses abióticos se analizó mediante RT-qPCR. HvSs1 y HvSs2 se expresaron preferencialmente durante el desarrollo del endospermo, y HvSs1 también fue un tránscrito abundante durante la germinación. HvSs1 se indujo en hojas en condiciones de anoxia y HvSs3 por estrés hídrico, y ambos genes se indujeron por tratamientos de frío. La localización subcelular de las cuatro isoformas no fue sólo citoplásmica, sino que también se localizaron en zonas próximas a retículo endoplásmico y en la cara interna de la membrana plasmática; además, se observó una co-localización de HvSS1 con el marcador de mitocondrias. Estos datos sugieren un papel distinto aunque parcialmente solapante de las cuatro Sacarosa Sintasas de cebada, descritas hasta la fecha. Las cinéticas de expresión de los genes que codifican los TFs más importantes implicados en la regulación génica durante el desarrollo del endospermo de cebada, se analizaron por RT-qPCR en ambos genotipos, demostrando que los TFs de la clase DOF aparecieron desregulados durante todo el proceso en Riso 1508 comparado con el cv. Bomi, aunque también se observaron diferencias significativas en algunos de los que codifican bZIPs. Estudios previos indicaban que el ortólogo de BLZ2 en maíz, O2, se regula post-traduccionalmente mediante un mecanismo de fosforilación/defosforilación reversible, y que la forma defosforilada es la fisiológicamente activa. En este trabajo se demostró que BLZ2 está sujeto a este tipo de regulación y que la proteín-fosfatasa HvPP2C2 está implicada en el proceso. La interacción de HvPP2C2 y BLZ2 tiene lugar en el núcleo celular únicamente en presencia de 100 μM ABA. En el mutante Riso 1508, BLZ2 se encuentra en un estado hiperfosforilado tanto durante la maduración como durante la germinación de la semilla, lo que dificultaría la unión de BLZ2 a las secuencias GLM en los promotores de los genes que codifican B-, C-,y ϒ- Hordeínas y CMe. Summary The seed is the main reproductive organ of spermatophyte plants allowing the spread of populations and ensuring their survival through its desiccation tolerance and because of their ability to germinate under optimum environmental conditions. Yield and economic value of cereal crops, that constitute the first world crop, depend largely on the efficiency with which they accumulate in the seed reserve substances: proteins, carbohydrates and lipids. The main carbohydrate accumulated in the barley seed is starch and the major protein fraction is that of prolamins (soluble in 70% ethanol); these proteins have a very low lysine content, an essential amino-acid for the diet of monogastric animals. In order to improve the nutritional value of the barley seed, different mutants have been obtained with a higher content of this amino-acid. Riso 1508 is one lysine-rich mutant whose mutation (lys3a) segregates as a single Mendelian gene with pleiotropic effects, such as a drastic reduction of genes encoding the trypsin inhibitor CMe and the B-, C-and ϒ-hordeins, but has not altered the expression of the gene encoding the D-hordeins. This latter gene lacks in its promotor the GLM motif (5’‐(G/A)TGA(G/C)TCA(T/C)‐3’), that is recognised by bZIP transcription factors In this work we have used the barley mutant Riso 1508 as a tool for better understanding gene regulation in seeds during the maturation and germination phases. To this aim, a transcriptomic analysis was performed comparing wild and mutant genotypes during seed maturation. Besides confirming variations in the expression of genes encoding reserve proteins, this analysis indicated that some genes related with carbohydrate metabolism were also affected. It was therefore decided to characterize the multigene family of sucrose synthases (SUSy) in barley. Two new genes were annotated, HvSs3 and HvSs4, and its expression was compared with that of genes HvSs1 and HvSs2, previously described in our laboratory. The expression of the four genes in different tissues and in response to abiotic stresses was analyzed by RTqPCR. HvSs1 and HvSs2 were preferentially expressed during the development of the endosperm, and the HvSs1 transcript was also abundant upon germination. HvSs1 was induced in leaves by anoxic conditions, HvSs3 by water stress, and both genes were induced by cold treatments. The subcellular localization of all four isoforms was not only cytoplasmic, but they could be found along the endoplasmic reticulum and at the inner side of the cell membrane; HvSS1, was also associated with the mitochondrial marker. These data suggest a distinct but partially overlapping roles for the barley sucrose synthases, described so far. The expression kinetics of the genes encoding the most important TFs involved in gene regulation during barley endosperm development was analyzed by RT-qPCR in both genotypes. These data show that the genes encoding DOF TFs were mis-regulated throughout the process in Riso 1508, although significant differences were also found among some of those encoding bZIPs. Previous studies indicated that the BLZ2 orthologue in maize, O2, was post-translationally regulated by reversible phosphorylation/dephosphorylation and that the dephosphorylated protein is the physiologically active form. In this work we demostrate that BLZ2 is under a similar regulation and that the proteinphosphatase HvPP2C2 is implicated in the process. The interaction between HvPP2C2 and BLZ2 takes place in the cell nucleus only in the presence of 100 μM ABA. In the Riso 1508 mutant, BLZ2 is found in a hyperphosphorylated state in the maturation phase and upon seed germination; because of this, the BLZ2 binding to the GLM promoter sequences of genes encoding B-, C- y ϒ- Hordeins and CMe would be decreased in the mutant.

Damage tolerance of cold drawn ferritic-austenitic stainless steels wires for prestressed concrete

Damage tolerance of high strength cold-drawn ferritic–austenitic stainless steel wires is assessed by means of tensile fracture tests of cracked wires. The fatigue crack is transversally propagated from the wire surface. The damage tolerance curve of the wires results from the empirical failure load when given as a function of crack depth. As a consequence of cold drawing, the wire microstructure is orientated along its longitudinal axis and anisotropic fracture behaviour is found at macrostructural level at the tensile failure of the cracked specimens. An in situ optical technique known as video image correlation VIC-2D is used to get an insight into this failure mechanism by tensile testing transversally fatigue cracked plane specimens extracted from the cold-drawn wires. Finally, the experimentally obtained damage tolerance curve of the cold-drawn ferritic–austenitic stainless steel wires is compared with that of an elementary plastic collapse model and existing data of two types of high strength eutectoid steel currently used as prestressing steel for concrete.

Design and Development of 35 % Efficient and lOOOX CPV Module with Sufficient Optical Alignment Tolerance

Modules are an important part of the CPV system. By pursing, in our objective of a 35% efficiency module, we need to look forward a significant improvement in the state of the art of CPV modules since no commercial module is capable of achieving that efficiency. Achieving this efficiency will require high efficiency cells, progress in the optics lenses that are implemented in these modules, and also integration into module. Basic design of 35% CPV module is presented considering for practical and rapid industry application. The output is 385 W while its weight is only 18 kg. In spite of its high concentration ratio reaching 1,000 X, it acceptance angle is as high as 1.1 degree.

Molecular basis of salt tolerance in Physcomitrella Patens model plant: potassium homeostasis and physiological roles of chx transporters

El suelo salino impone un estrés abiótico importante que causa graves problemas en la agricultura ya que la mayoría de los cultivos se ven afectados por la salinidad debido a efectos osmóticos y tóxicos. Por ello, la contaminación y la escasez de agua dulce, la salinización progresiva de tierras y el aumento exponencial de la población humana representan un grave problema que amenaza la seguridad alimentaria mundial para las generaciones futuras. Por lo tanto, aumentar la tolerancia a la salinidad de los cultivos es un objetivo estratégico e ineludible para garantizar el suministro de alimentos en el futuro. Mantener una óptima homeostasis de K+ en plantas que sufren estrés salino es un objetivo importante en el proceso de obtención de plantas tolerantes a la salinidad. Aunque el modelo de la homeostasis de K+ en las plantas está razonablemente bien descrito en términos de entrada de K+, muy poco se sabe acerca de los genes implicados en la salida de K+ o de su liberación desde la vacuola. En este trabajo se pretende aclarar algunos de los mecanismos implicados en la homeostasis de K+ en plantas. Para ello se eligió la briofita Physcomitrella patens, una planta no vascular de estructura simple y de fase haploide dominante que, entre muchas otras cualidades, hacen que sea un modelo ideal. Lo más importante es que no sólo P. patens es muy tolerante a altas concentraciones de Na+, sino que también su posición filogenética en la evolución de las plantas abre la posibilidad de estudiar los cambios claves que, durante el curso de la evolución, se produjeron en las diversas familias de los transportadores de K+. Se han propuesto varios transportadores de cationes como candidatos que podrían tener un papel en la salida de K+ o su liberación desde la vacuola, especialmente miembros de la familia CPA2 que contienen las familias de transportadores KEA y CHX. En este estudio se intenta aumentar nuestra comprensión de las funciones de los transportadores de CHX en las células de las plantas usando P. patens, como ya se ha dicho. En esta especie, se han identificado cuatro genes CHX, PpCHX1-4. Dos de estos genes, PpCHX1 y PpCHX2, se expresan aproximadamente al mismo nivel que el gen PpACT5, y los otros dos genes muestran una expresión muy baja. La expresión de PpCHX1 y PpCHX2 en mutantes de Escherichia coli defectivos en el transporte de K+ restauraron el crecimiento de esta cepa en medios con bajo contenido de K+, lo que viii sugiere que la entrada de K+ es energizada por un mecanismo de simporte con H+. Por otra parte, estos transportadores suprimieron el defecto asociado a la mutación kha1 en Saccharomyces cerevisiae, lo que sugiere que podrían mediar un antiporte en K+/H+. La proteína PpCHX1-GFP expresada transitoriamente en protoplastos de P. patens co-localizó con un marcador de Golgi. En experimentos similares, la proteína PpCHX2-GFP localizó aparentemente en la membrana plasmática y tonoplasto. Se construyeron las líneas mutantes simples de P. patens ΔPpchx1 y ΔPpchx2, y también el mutante doble ΔPpchx2 ΔPphak1. Los mutantes simples crecieron normalmente en todas las condiciones ensayadas y mostraron flujos de entrada normales de K+ y Rb+; la mutación ΔPpchx2 no aumentó el defecto de las plantas ΔPphak1. En experimentos a largo plazo, las plantas ΔPpchx2 mostraron una retención de Rb+ ligeramente superior que las plantas silvestres, lo que sugiere que PpCHX2 promueve la transferencia de Rb+ desde la vacuola al citosol o desde el citosol al medio externo, actuando en paralelo con otros transportadores. Sugerimos que transportadores de K+ de varias familias están involucrados en la homeostasis de pH de orgánulos ya sea mediante antiporte K+/H+ o simporte K+-H+.ix ABSTRACT Soil salinity is a major abiotic stress causing serious problems in agriculture as most crops are affected by it. Moreover, the contamination and shortage of freshwater, progressive land salinization and exponential increase of human population aggravates the problem implying that world food security may not be ensured for the next generations. Thus, a strategic and an unavoidable goal would be increasing salinity tolerance of plant crops to secure future food supply. Maintaining an optimum K+ homeostasis in plants under salinity stress is an important trait to pursue in the process of engineering salt tolerant plants. Although the model of K+ homeostasis in plants is reasonably well described in terms of K+ influx, very little is known about the genes implicated in K+ efflux or release from the vacuole. In this work, we aim to clarify some of the mechanisms involved in K+ homeostasis in plants. For this purpose, we chose the bryophyte plant Physcomitrella patens, a nonvascular plant of simple structure and dominant haploid phase that, among many other characteristics, makes it an ideal model. Most importantly, not only P. patens is very tolerant to high concentrations of Na+, but also its phylogenetic position in land plant evolution opens the possibility to study the key changes that occurred in K+ transporter families during the course of evolution. Several cation transporter candidates have been proposed to have a role in K+ efflux or release from the vacuole especially members of the CPA2 family which contains the KEA and CHX transporter families. We intended in this study to increase our understanding of the functions of CHX transporters in plant cells using P. patens, in which four CHX genes have been identified, PpCHX1-4. Two of these genes, PpCHX1 and PpCHX2, are expressed at approximately the same level as the PpACT5 gene, but the other two genes show an extremely low expression. PpCHX1 and PpCHX2 restored growth of Escherichia coli mutants on low K+-containing media, suggesting they mediated K+ uptake that may be energized by symport with H+. In contrast, these genes suppressed the defect associated to the kha1 mutation in Saccharomyces cerevisiae, which suggest that they might mediate K+/H+ antiport. PpCHX1-GFP protein transiently expressed in P. patens protoplasts co-localized with a Golgi marker. In similar experiments, the PpCHX2-GFP protein appeared to localize to tonoplast and plasma x membrane. We constructed the ΔPpchx1 and ΔPpchx2 single mutant lines, and the ΔPpchx2 ΔPphak1 double mutant. Single mutant plants grew normally under all the conditions tested and exhibited normal K+ and Rb+ influxes; the ΔPpchx2 mutation did not increase the defect of ΔPphak1 plants. In long-term experiments, ΔPpchx2 plants showed a slightly higher Rb+ retention than wild type plants, which suggests that PpCHX2 mediates the transfer of Rb+ from either the vacuole to the cytosol or from the cytosol to the external medium in parallel with other transporters. We suggest that K+ transporters of several families are involved in the pH homeostasis of organelles by mediating either K+/H+ antiport or K+-H+ symport.

Frost tolerance of eight olive cultivars

En este trabajo se estudia la relacion entre la resistencia al frio de 8 variedades de olivo observada en campo y la medida en laboratorio, a partir de la temperatura de congelacion letal. Se observo una correlacion entre el porcentaje de brotes helado y la temperatura de congelacion letal 50%. Las variedades mas resistentes fueron Cornicabra, Arbequina y Picual. Las mas sensibles fue Empeltre.

Thermographic imaging: assessment of drought and heat tolerance in Spanish germplasm of Brachypodium distachyon.

The annual grass Brachypodium distachyon has been recently recognized as the model plant for functional genomics of temperate grasses, including cereals of economic relevance like wheat and barley. Sixty-two lines of B. distachyon were assessed for response to drought stress and heat tolerance. All these lines, except the reference genotype BD21, derive from specimens collected in 32 distinct locations of the Iberian Peninsula, covering a wide range of geo- climatic conditions. Sixteen lines of Brachypodium hybridum, an allotetraploid closely related to B. distachyon were used as reference of abiotic-stress well-adapted genotypes. Drought tolerance was assessed in a green-house trial. At the rosette-stage, no irrigation was applied to treated plants whereas their replicates at the control were maintained well watered during all the experiment. Thermographic images of treated and control plants were taken after 2 and 3 weeks of drought treatment, when stressed plants showed medium and extreme wilting symptoms. The mean leaf temperature of stressed (LTs) and control (LTc) plants was estimated based upon thermographic records from selected pixels (183 per image) that strictly correspond to leaf tissue. The response to drought was based on the analysis of two parameters: LTs and the thermal difference (TD) between stressed and control plants (LTs – LTc). The response to heat stress was based on LTc. Comparison of the mean values of these parameters showed that: 1) Genotypes better adapted to drought (B. hybridum lines) presented a higher LTs and TD than B. distachyon lines. 2) Under high temperature conditions, watered plants of B. hybridum lines maintained lower LTc than those of B. distachyon. Those results suggest that in these species adaptation to drought is linked to a more efficient stomata regulation: under water stress stomata are closed, increasing foliar temperature but also water use efficiency by reducing transpiration. With high temperature and water availability the results are less definite, but still seems that opening stomata allow plants to increase transpiration and therefore to diminish foliar temperature.

Effects of hydrogen assisted stress corrosion on damage tolerance of a high-strength duplex stainless steel wire for prestressing concrete

The study brings new insights on the hydrogen assisted stress corrosion on damage tolerance of a high-strength duplex stainless steel wire which concerns its potential use as active reinforcement for concrete prestressing. The adopted procedure was to experimentally state the effect of hydrogen on the damage tolerance of cylindrical smooth and precracked wire specimens exposed to stress corrosion cracking using the aggressive medium of the standard test developed by FIP (International Prestressing Federation). Stress corrosion testing, mechanical fracture tests and scanning electron microscopy analysis allowed the damage assessment, and explain the synergy between mechanical loading and environment action on the failure sequence of the wire. In presence of previous damage, hydrogen affects the wire behavior in a qualitative sense, consistently to the fracture anisotropy attributable to cold drawing, but it does not produce quantitative changes since the steel fully preserves its damage tolerance.