48,816 research outputs found
Collaborative Verification-Driven Engineering of Hybrid Systems
Hybrid systems with both discrete and continuous dynamics are an important
model for real-world cyber-physical systems. The key challenge is to ensure
their correct functioning w.r.t. safety requirements. Promising techniques to
ensure safety seem to be model-driven engineering to develop hybrid systems in
a well-defined and traceable manner, and formal verification to prove their
correctness. Their combination forms the vision of verification-driven
engineering. Often, hybrid systems are rather complex in that they require
expertise from many domains (e.g., robotics, control systems, computer science,
software engineering, and mechanical engineering). Moreover, despite the
remarkable progress in automating formal verification of hybrid systems, the
construction of proofs of complex systems often requires nontrivial human
guidance, since hybrid systems verification tools solve undecidable problems.
It is, thus, not uncommon for development and verification teams to consist of
many players with diverse expertise. This paper introduces a
verification-driven engineering toolset that extends our previous work on
hybrid and arithmetic verification with tools for (i) graphical (UML) and
textual modeling of hybrid systems, (ii) exchanging and comparing models and
proofs, and (iii) managing verification tasks. This toolset makes it easier to
tackle large-scale verification tasks
Approaching the ultimate capacity limit in deep-space optical communication
The information capacity of an optical channel under power constraints is
ultimately limited by the quantum nature of transmitted signals. We discuss
currently available and emerging photonic technologies whose combination can be
shown theoretically to enable nearly quantum-limited operation of a noisy
optical communication link in the photon-starved regime, with the information
rate scaling linearly in the detected signal power. The key ingredients are
quantum pulse gating to facilitate mode selectivity, photon-number-resolved
direct detection, and a photon-efficient high-order modulation format such as
pulse position modulation, frequency shift keying, or binary phase shift keyed
Hadamard words decoded optically using structured receivers.Comment: 9 pages, 4 figures. Presented at Free-Space Laser Communications
XXXI, 4-6 February 2019, San Francisco, C
Microfluidics-based approaches to the isolation of African trypanosomes
African trypanosomes are responsible for significant levels of disease in both humans and animals. The protozoan parasites are free-living flagellates, usually transmitted by arthropod vectors, including the tsetse fly. In the mammalian host they live in the bloodstream and, in the case of human-infectious species, later invade the central nervous system. Diagnosis of the disease requires the positive identification of parasites in the bloodstream. This can be particularly challenging where parasite numbers are low, as is often the case in peripheral blood. Enriching parasites from body fluids is an important part of the diagnostic pathway. As more is learned about the physicochemical properties of trypanosomes, this information can be exploited through use of different microfluidic-based approaches to isolate the parasites from blood or other fluids. Here, we discuss recent advances in the use of microfluidics to separate trypanosomes from blood and to isolate single trypanosomes for analyses including drug screening
A Top-Down Approach to Managing Variability in Robotics Algorithms
One of the defining features of the field of robotics is its breadth and
heterogeneity. Unfortunately, despite the availability of several robotics
middleware services, robotics software still fails to smoothly handle at least
two kinds of variability: algorithmic variability and lower-level variability.
The consequence is that implementations of algorithms are hard to understand
and impacted by changes to lower-level details such as the choice or
configuration of sensors or actuators. Moreover, when several algorithms or
algorithmic variants are available it is difficult to compare and combine them.
In order to alleviate these problems we propose a top-down approach to
express and implement robotics algorithms and families of algorithms so that
they are both less dependent on lower-level details and easier to understand
and combine. This approach goes top-down from the algorithms and shields them
from lower-level details by introducing very high level abstractions atop the
intermediate abstractions of robotics middleware. This approach is illustrated
on 7 variants of the Bug family that were implemented using both laser and
infra-red sensors.Comment: 6 pages, 5 figures, Presented at DSLRob 2013 (arXiv:cs/1312.5952
End-to-End Tracking and Semantic Segmentation Using Recurrent Neural Networks
In this work we present a novel end-to-end framework for tracking and
classifying a robot's surroundings in complex, dynamic and only partially
observable real-world environments. The approach deploys a recurrent neural
network to filter an input stream of raw laser measurements in order to
directly infer object locations, along with their identity in both visible and
occluded areas. To achieve this we first train the network using unsupervised
Deep Tracking, a recently proposed theoretical framework for end-to-end space
occupancy prediction. We show that by learning to track on a large amount of
unsupervised data, the network creates a rich internal representation of its
environment which we in turn exploit through the principle of inductive
transfer of knowledge to perform the task of it's semantic classification. As a
result, we show that only a small amount of labelled data suffices to steer the
network towards mastering this additional task. Furthermore we propose a novel
recurrent neural network architecture specifically tailored to tracking and
semantic classification in real-world robotics applications. We demonstrate the
tracking and classification performance of the method on real-world data
collected at a busy road junction. Our evaluation shows that the proposed
end-to-end framework compares favourably to a state-of-the-art, model-free
tracking solution and that it outperforms a conventional one-shot training
scheme for semantic classification
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