122 research outputs found
Modifying Is Better Than Deleting: A New Approach To Base Revision
We present three approaches to belief base revision, which are examined also in the case in which the sentences in the base are partitioned between those which can and those which cannot be changed; the approaches are shown to be semantically equivalent. A new approach is then presented, based on the modification of individual rules, instead of deletion. The resulting base is semantically equivalent to that generated by the other approaches, in the sense that it has the same models, but the rule part alone has less models, that is, is subjected to a smaller change
Analytic Modal Revision For Multi-Agent Systems
We present two models of hierarchical structured multi-agents, and we describe how to obtain a modal knowledge base from distributed sources. We then propose a computationally oriented revision procedure for modal knowledge bases. This procedure is based on a labelled tableaux calculi supplemented with a formalism to record the dependencies of the formulae. The dependencies are then used to reconstruct the minimal inconsistent sets, and the sub-formulae responsible for the inconsistencies are revised according to well-defined chains of modal functions
How Aerospace and Transportation Design Challenges can be addressed from Simulation-based Virtual Prototyping for Distributed Safety Critical Automotive Applications
International audienceThe reduction of development and product costs for distributed and software dominated safety-critical automotive applications can only be achieved via novel methodologies and tool sets that address fault injection/analysis and integration testing via simulation-based virtual prototyping. In fact, earlier discovery of design errors and initial proof of safety in critical conditions should be addressed earlier using a system virtual prototype, before hardware and software implementations are available. In this paper, we propose a methodology that allows evaluating fault-tolerant system architectures in the presence of errors caused by faults of hardware elements or interferences. We illustrate how the paradigm shift from physical to virtual integration platforms can be applied to Aerospace and Transportation domains effectively
Understanding the Impact of Cutting in Quantum Circuits Reliability to Transient Faults
Quantum Computing is a highly promising new computation paradigm. Unfortunately, quantum bits (qubits) are extremely fragile and their state can be gradually or suddenly modified by intrinsic noise or external perturbation. In this paper, we target the sensitivity of quantum circuits to radiation-induced transient faults. We consider quantum circuit cuts that split the circuit into smaller independent portions, and understand how faults propagate in each portion. As we show, the cuts have different vulnerabilities, and our methodology successfully identifies the circuit portion that is more likely to contribute to the overall circuit error rate. Our evaluation shows that a circuit cut can have a 4.6x higher probability than the other cuts, when corrupted, to modify the circuit output. Our study, identifying the most critical cuts, moves towards the possibility of implementing a selective hardening for quantum circuits
Carbon nitride thin films as all-in-one technology for photocatalysis
Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of dis..
Understanding the Effect of Transpilation in the Reliability of Quantum Circuits
Transpiling is a necessary step to map a logical quantum algorithm to a circuit executed on a physical quantum machine, according to the available gate set and connectivity topology. Different transpiling approaches try to minimize the most critical parameters for the current transmon technology, such as Depth and CNOT number. Crucially, these approaches do not take into account the reliability of the circuit. In particular, transpilation can modify how radiation-induced transient faults propagate. In this paper, we aim at advancing the understanding of transpilation impact on fault propagation by investigating the low-level reliability of several transpiling approaches. We considered 4 quantum algorithms transpiled for 2 different architectures, increasing the number of qubits, and all possible logical-to-physical qubit mapping, adding to a total of 4, 640 transpiled circuits. We inject a total of 202, 124 faults and track their propagation. Our experiments show that by simply choosing the proper transpilation, the reliability of the circuit can improve by up to 14%
Colorimetric Detection of Perfluorinated Compounds by All-Polymer Photonic Transducers
We report on the highly sensitive optical and
colorimetric detection of perfluorinated compounds in the
vapor phase achieved by all-polymer dielectric mirrors. High
optical quality and uniformly distributed Bragg reflectors were
fabricated by alternating thin films of poly(N-vinylcarbazole)
and Hyflon AD polymers as high and low refractive index
medium, respectively. A new processing procedure has been
developed to compatibilize the deposition of poly(N-vinylcarbazole)
with the highly solvophobic Hyflon AD polymer
layers to achieve mutual processability between the two
polymers and fabricate the devices. As a proof of principle,
sensing measurements were performed using the Galden
HT55 polymer as a prototype of the perfluorinated
compound. The Bragg stacks show a strong chromatic response upon exposure to this compound, clearly detectable as both
spectral and intensity variations. Conversely, Bragg mirrors fabricated without fluorinated polymers do not show any detectable
response, demonstrating that the Hyflon AD polymer acts as the active and selective medium for sensing perfluorinated species.
These results demonstrate that organic dielectric mirrors containing perfluorinated polymers can represent an innovative
colorimetric monitoring system for fluorinated compounds, suitable to improve both environmental safety and quality of life
QuFI: a Quantum Fault Injector to Measure the Reliability of Qubits and Quantum Circuits
Quantum computing is a new technology that is expected to revolutionize the
computation paradigm in the next few years. Qubits exploit the quantum physics
proprieties to increase the parallelism and speed of computation.
Unfortunately, besides being intrinsically noisy, qubits have also been shown
to be highly susceptible to external sources of faults, such as ionizing
radiation. The latest discoveries highlight a much higher radiation sensitivity
of qubits than traditional transistors and identify a much more complex fault
model than bit-flip. We propose a framework to identify the quantum circuits
sensitivity to radiation-induced faults and the probability for a fault in a
qubit to propagate to the output. Based on the latest studies and radiation
experiments performed on real quantum machines, we model the transient faults
in a qubit as a phase shift with a parametrized magnitude. Additionally, our
framework can inject multiple qubit faults, tuning the phase shift magnitude
based on the proximity of the qubit to the particle strike location. As we show
in the paper, the proposed fault injector is highly flexible, and it can be
used on both quantum circuit simulators and real quantum machines. We report
the finding of more than 285M injections on the Qiskit simulator and 53K
injections on real IBM machines. We consider three quantum algorithms and
identify the faults and qubits that are more likely to impact the output. We
also consider the fault propagation dependence on the circuit scale, showing
that the reliability profile for some quantum algorithms is scale-dependent,
with increased impact from radiation-induced faults as we increase the number
of qubits. Finally, we also consider multi qubits faults, showing that they are
much more critical than single faults. The fault injector and the data
presented in this paper are available in a public repository to allow further
analysis
Ultraviolet Radiation inside Interstellar Grain Aggregates. II. Field Depolarization
We study the polarization of the UV light within the cavities of interstellar grain aggregates modeled as homo- geneous spheres containing several spherical voids. The incident field is a linearly polarized plane wave. We found that field depolarization occurs in all examined cases so that the field within the cavities has the features of an ellip- tically polarized wave. The depolarization of the field does not depend on the material of the grains but on the geometry of the problem only. The implications of this result for the interstellar photochemistry are briefly discussed
Ultraviolet Radiation inside Interstellar Grain Aggregates. I. The Density of Radiation
We study the distribution of energy density inside dust grain aggregates through an approach based on the multipole expansion of the electromagnetic fields. A significant fraction of the energy of the impinging wave is found throughout the interiors of grains. Implications for extraterrestrial prebiotic chemistry are discussed
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