On Resilient Behaviors in Computational Systems and Environments

The present article introduces a reference framework for discussing resilience of computational systems. Rather than a property that may or may not be exhibited by a system, resilience is interpreted here as the emerging result of a dynamic process. Said process represents the dynamic interplay between the behaviors exercised by a system and those of the environment it is set to operate in. As a result of this interpretation, coherent definitions of several aspects of resilience can be derived and proposed, including elasticity, change tolerance, and antifragility. Definitions are also provided for measures of the risk of unresilience as well as for the optimal match of a given resilient design with respect to the current environmental conditions. Finally, a resilience strategy based on our model is exemplified through a simple scenario.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s40860-015-0002-6 The paper considerably extends the results of two conference papers that are available at http://ow.ly/KWfkj and http://ow.ly/KWfgO. Text and formalism in those papers has been used or adapted in the herewith submitted pape

A model for trustworthy orchestration in the internet of things

Embedded systems such as Cyber-Physical Systems (CPS) are typically designed as a network of multiple interacting elements with physical input (or sensors) and output (or actuators). One aspect of interest of open systems is fidelity, or the compliance between physical figures of interest and their internal representation. High fidelity is defined as a stable mapping between actions in the physical domain and intended or expected values in the system domain and deviations from fidelity are quantifiable over time by some appropriate informative variable. In this paper, we provide a model for designing such systems based on a framework for trustworthiness monitoring and we provide a Jason implementation to evaluate the feasibility of our approach. In particular, we build a bridge between a standard publish/subscribe framework for CPS called MQTT and Jason to enable automatic reasoning about trustworthines

Physics-Informed Neural Networks for 2nd order ODEs with sharp gradients

In this work, four different methods based on Physics-Informed Neural Networks (PINNs) for solving Differential Equations (DE) are compared: Classic-PINN that makes use of Deep Neural Networks (DNNs) to approximate the DE solution;Deep-TFC improves the efficiency of classic-PINN by employing the constrained expression from the Theory of Functional Connections (TFC) so to analytically satisfy the DE constraints;PIELM that improves the accuracy of classic-PINN by employing a single-layer NN trained via Extreme Learning Machine (ELM) algorithm;X-TFC, which makes use of both constrained expression and ELM. The last has been recently introduced to solve challenging problems affected by discontinuity, learning solutions in cases where the other three methods fail. The four methods are compared by solving the boundary value problem arising from the 1D Steady-State Advection–Diffusion Equation for different values of the diffusion coefficient. The solutions of the DEs exhibit steep gradients as the value of the diffusion coefficient decreases, increasing the challenge of the problem

Heavy Metal Levels in Dog Liver and Kidney in Naples (Campania, Italy)

The aim of the current study was to carry out a retrospective analysis of heavy metal (Pb, Cd, and Hg) levels in liver and kidney of 38 dogs living in an urban habitat (city of Naples). Tissues were homogenized, digested in a microwave digestion system, and analyzed by atomic absorption spectrometry. The results of this study showed generally low levels of heavy metals in tissues of all examined dogs; only mercury concentrations in kidneys of pet dogs were higher than in stray dogs, and no significant age-dependent differences in metal levels were shown between the two groups. In conclusion, these results suggest the involvement of ad hoc-formulated pet food exposure to heavy metals in domestic animals

Levels of heavy metals in liver and kidney of dogs from urban environment

Lead, cadmium and mercury were detected in liver and kidney tissue of dogs from an urban habitat. Samples were digested in a microwave system and analyzed by atomic absorption spectroscopy. Results of the current study showed that at least one of the three heavy metals was detected in tissues of all examined dogs. These findings make us suppose that humans are exposed to the same heavy metals similar to those of dogs that are exposed since they share the same environment. Mercury concentrations detected in kidney of household dogs were higher than stray dogs, therefore the involvement of pet food in exposure to mercury can be supposed

AUTONOMOUS FORMATION KEEPING AND RECONFIGURATION FOR REMOTE SENSING SPACECRAFT

ABSTRACT This paper is devoted to the realistic demonstration of a complete Guidance, Navigation and Control (GNC) system for formation flying spacecraft in Low Earth orbit (LEO). Numerous technical novelties in the areas of formation flying guidance, GPS-based relative navigation, and impulsive relative orbit control have made this possible, but the primary contribution of this research work stems from the design and implementation of a comprehensive formation flying system through the successful integration of various techniques. This research has led to the full development, testing and validation of the GNC flight code to be embedded in the on-board computer of the Main spacecraft of the Swedish PRISMA technology demonstration. Furthermore key guidance and control algorithms presented here are going to be demonstrated for the first time on-board the German TanDEM-X formation flying mission. Overall this paper focuses on realistic application cases closely related to upcoming formation flying missions. The intention is to realize a practical and reliable way to a technology which is discussed and studied since decades but is still confined in research laboratories. Hardwarein-the-loop real-time simulations including flight computers show that simple techniques, which exploit the natural orbit motion to full extent, can meet the demanding requirements of the long-term close formation flying

The morphology and clinical importance of the axillary arch

The axillary arch is the main variation of the axillary muscle. It was first described by Ramsay in 1795. In its classical form, it arises from the latissimus dorsi muscle and extends from this towards the pectoralis major, crossing the base of the axilla and creating a close relationship with the elements of the axillary neurovascular bundle. We describe the finding of 9 axillary arches, including one case of a bilateral arrangement. We develop a searching and finding technique for the axillary arch, essential for the safe and successful development of surgical procedures in the axillary region. Knowledge of this muscle variation and the possibility of finding it during axillary procedures is crucial for lymph node staging and lymphadenectomy and is also important for differential diagnosis in compressive pathologies of the axillary vessels and brachial plexus