Formal Design of Asynchronous Fault Detection and Identification Components using Temporal Epistemic Logic

Autonomous critical systems, such as satellites and space rovers, must be able to detect the occurrence of faults in order to ensure correct operation. This task is carried out by Fault Detection and Identification (FDI) components, that are embedded in those systems and are in charge of detecting faults in an automated and timely manner by reading data from sensors and triggering predefined alarms. The design of effective FDI components is an extremely hard problem, also due to the lack of a complete theoretical foundation, and of precise specification and validation techniques. In this paper, we present the first formal approach to the design of FDI components for discrete event systems, both in a synchronous and asynchronous setting. We propose a logical language for the specification of FDI requirements that accounts for a wide class of practical cases, and includes novel aspects such as maximality and trace-diagnosability. The language is equipped with a clear semantics based on temporal epistemic logic, and is proved to enjoy suitable properties. We discuss how to validate the requirements and how to verify that a given FDI component satisfies them. We propose an algorithm for the synthesis of correct-by-construction FDI components, and report on the applicability of the design approach on an industrial case-study coming from aerospace.Comment: 33 pages, 20 figure

Rod photoreceptors drive circadian photoentrainment across a wide range of light intensities.

In mammals, synchronization of the circadian pacemaker in the hypothalamus is achieved through direct input from the eyes conveyed by intrinsically photosensitive retinal ganglion cells (ipRGCs). Circadian photoentrainment can be maintained by rod and cone photoreceptors, but their functional contributions and their retinal circuits that impinge on ipRGCs are not well understood. Using mice that lack functional rods or in which rods are the only functional photoreceptors, we found that rods were solely responsible for photoentrainment at scotopic light intensities. Rods were also capable of driving circadian photoentrainment at photopic intensities at which they were incapable of supporting a visually guided behavior. Using mice in which cone photoreceptors were ablated, we found that rods signal through cones at high light intensities, but not at low light intensities. Thus, rods use two distinct retinal circuits to drive ipRGC function to support circadian photoentrainment across a wide range of light intensities

Effect of growth regulators and Physiological Gradients on the High frequency plant regeneration from the long-term callus cultures of different germplasms of Rice (Oryza sativa L.)

Callus cultures of rice were initiated from mature embryos of different cultivars on LS medium containing 2 mg/L 2,4-D. Increasing concentrations of 2,4-D and 2,4-5T also increased the frequency of callus initiation in all the cultivars tested. Of different cultivars, Tellahamsa was found to be superior for callus initiation. Genotypic differences for plant regeneration were also observed. Cultivar Tellahamsa showed the highest (65-75%) frequency of plant differentiation followed by DGWG, Yerragaluvadlu, Surekha, Basmati-370, Bala, Chakko amubi, Jaya and IR-8. Callus cultures of rice cultivar Bala grown on a shoot-forming medium (LS + 1 mg/L IAA + 4 mg/L KN + 2% sucrose) were exposed to gibberellic acid and abscisic acid for varying lengths of time and at different periods during culture. Gibberellic acid totally suppressed the organogenesis in callus cultures of rice. The results suggest that if the tissue accumulated sufficient gibberellic acid prior to the initiation of meristemoids and shoot primordia, repression of shoot formation occurred. This repression was not reversed by increasing the levels of IAA and KN in the medium, but abscisic acid could partially overcome the gibberellic acid repression of shoot formation in rice callus. It has been observed in rice that shoots usually emerge from the basal portions of callus. This observation suggested that perhaps physiological gradients of materials were operative during the organ initiation process. To test this hypothesis, starch content and the enzyme activity of malate dehydrogenase in upper and lower portions of shoot-forming and non-shoot-forming callus were determined. Starch began to accumulate in both upper and lower portions of the shoot forming tissues within 4 days of culture. The rate of accumulation however, was faster and more in the lower portion of the callus leading to a peak of accumulation on day 8 in culture, i.e., prior to shoot formation. Non-shoot-forming callus cultures accumulated little starch during the same period of culture. Malate dehydrogenase (MDH) activity was examined in order to know the overall rate of respiration. In the upper segment of shoot-forming callus, the activity of MDH was very high by day 4 but declined continuously thereafter. The rate of activity of the enzyme was significantly higher beyond four days in culture in case of the lower portion of the shoot forming callus. Enzyme activity was lower in the non-shoot-forming portions (both upper and lower) of the callus. The higher rate of enzyme activity for the upper portion of the tissue could be attributed to increased oxygen availability. Thus, the evidence for the idea that concentrations of gradients or physiological gradients of substances into the callus tissue may be the operative factors promoting organ initiation in vitro is presented

Effects of sea level rise on salinity and tidal flooding patterns in the Guadiana Estuary

Sea level rise is a worldwide concern as a high percentage of the population accommodates coastal areas. The focus of this study is the impact of sea level rise in the Guadiana Estuary, an estuary in the Iberian Peninsula formed at the interface of the Guadiana River and the Gulf of Cadiz. Estuaries will be impacted by sea level rise as these transitional environments host highly diverse and complex marine ecosystems. The major consequences of sea level rise are the intrusion of salt from the sea into fresh water and an increase in flooding area. As the physical, chemical, and biological components of estuaries are sensitive to changes in salinity, the purpose of this study is to further evaluate salt intrusion in the Guadiana Estuary caused by sea level rise. Hydrodynamics of the Guadiana Estuary were simulated in a two-dimensional numerical model with the MOHID water modeling system. A previously developed hydrodynamic model was implemented to further examine changes in salinity distribution in the estuary in response to sea level rise. Varying tidal amplitudes, freshwater discharge from the Guadiana River and bathymetries of the estuary were incorporated in the model to fully evaluate the impacts of sea level rise on salinity distribution and flooding areas of the estuary. Results show an overall increase in salinity and land inundation in the estuary in response to sea level rise.info:eu-repo/semantics/publishedVersio

Utilization of phosphorus for casein biosynthesis in the mammary gland. II. Incorporation of P<SUP>32</SUP> into free phosphopeptides of milk and of mammary gland

This article does not have an abstract

Analysis of thrust force in drilling cotton with bamboo blended fibre-reinforced composites using Box-Behnken methodology

267-273In this study, cotton/bamboo woven fabric reinforced composite has been subjected to drilling operation and thrust force is analysed for different combination of feed rate, cutting speed and drill geomentry. Box-Behnken experimental design is used to optimize the cutting parameters along with the input parameters, such as drill- bit geomentry, spindle speed and rate of feed. Further, a drill with standard twist is used for drilling operation. The results show that with the increase in thrust force, feed rate increases and cutting speed experiences decrease when drill diameter is increased. The SEM analysis is also done to reveal about various damages, like fibre pullout, peel off, uncut fibres and voids

Analysis of thrust force in drilling cotton with bamboo blended fibre-reinforced composites using Box-Behnken methodology

In this study, cotton/bamboo woven fabric reinforced composite has been subjected to drilling operation and thrust force is analysed for different combination of feed rate, cutting speed and drill geomentry. Box-Behnken experimental design is used to optimize the cutting parameters along with the input parameters, such as drill- bit geomentry, spindle speed and rate of feed. Further, a drill with standard twist is used for drilling operation. The results show that with the increase in thrust force, feed rate increases and cutting speed experiences decrease when drill diameter is increased. The SEM analysis is also done to reveal about various damages, like fibre pullout, peel off, uncut fibres and voids.