13,549 research outputs found
Real-time support for high performance aircraft operation
The feasibility of real-time processing schemes using artificial neural networks (ANNs) is investigated. A rationale for digital neural nets is presented and a general processor architecture for control applications is illustrated. Research results on ANN structures for real-time applications are given. Research results on ANN algorithms for real-time control are also shown
A Smart Modular Wireless System for Condition Monitoring Data Acquisition
Smart sensors, big data, the cloud and distributed data processing are some of the most interning changes in the way we collect, manage and treat data in recent years. These changes have not significantly influenced the common practices in condition monitoring for shipping. In part this is due to the reduced trust in data security, data ownership issues, lack of technological integration and obscurity of direct benefit. This paper presents a method of incorporating smart sensor techniques and distributed processing in data acquisition for condition monitoring to assist decision support for maintenance actions addressing these inhibitors
Advanced avionics concepts: Autonomous spacecraft control
A large increase in space operations activities is expected because of Space Station Freedom (SSF) and long range Lunar base missions and Mars exploration. Space operations will also increase as a result of space commercialization (especially the increase in satellite networks). It is anticipated that the level of satellite servicing operations will grow tenfold from the current level within the next 20 years. This growth can be sustained only if the cost effectiveness of space operations is improved. Cost effectiveness is operational efficiency with proper effectiveness. A concept is presented of advanced avionics, autonomous spacecraft control, that will enable the desired growth, as well as maintain the cost effectiveness (operational efficiency) in satellite servicing operations. The concept of advanced avionics that allows autonomous spacecraft control is described along with a brief description of each component. Some of the benefits of autonomous operations are also described. A technology utilization breakdown is provided in terms of applications
Monte-Carlo methods make Dempster-Shafer formalism feasible
One of the main obstacles to the applications of Dempster-Shafer formalism is its computational complexity. If we combine m different pieces of knowledge, then in general case we have to perform up to 2(sup m) computational steps, which for large m is infeasible. For several important cases algorithms with smaller running time were proposed. We prove, however, that if we want to compute the belief bel(Q) in any given query Q, then exponential time is inevitable. It is still inevitable, if we want to compute bel(Q) with given precision epsilon. This restriction corresponds to the natural idea that since initial masses are known only approximately, there is no sense in trying to compute bel(Q) precisely. A further idea is that there is always some doubt in the whole knowledge, so there is always a probability p(sub o) that the expert's knowledge is wrong. In view of that it is sufficient to have an algorithm that gives a correct answer a probability greater than 1-p(sub o). If we use the original Dempster's combination rule, this possibility diminishes the running time, but still leaves the problem infeasible in the general case. We show that for the alternative combination rules proposed by Smets and Yager feasible methods exist. We also show how these methods can be parallelized, and what parallelization model fits this problem best
Advanced sensors technology survey
This project assesses the state-of-the-art in advanced or 'smart' sensors technology for NASA Life Sciences research applications with an emphasis on those sensors with potential applications on the space station freedom (SSF). The objectives are: (1) to conduct literature reviews on relevant advanced sensor technology; (2) to interview various scientists and engineers in industry, academia, and government who are knowledgeable on this topic; (3) to provide viewpoints and opinions regarding the potential applications of this technology on the SSF; and (4) to provide summary charts of relevant technologies and centers where these technologies are being developed
The integration of hazard evaluation procedures and requirements engineering for safety-critical embedded systems
Although much work has been done on assessing safety requirements in
programmable systems, one very important aspect, the integration of hazard
evaluation procedures and requirements engineering, has been somewhat neglected.
This thesis describes the derivation and application of a methodology, HAZAPS
(HAZard Assessment in Programmable Systems). The methodology assists at the
requirements stage in the development of safety-critical embedded systems. The
objectives are to identify hazards in programmable systems, construct and model the
associated safety requirements, and, finally, to assess these requirements. HAZAPS
integrates safety engineering and software modelling techniques. The analysis of
more than 300 computer related incidents provided the criteria used to identify, select
and modify safety engineering techniques. [Continues.
Programmable interactions with biomimetic DNA linkers at fluid membranes and interfaces
At the heart of the structured architecture and complex dynamics of
biological systems are specific and timely interactions operated by
biomolecules. In many instances, biomolecular agents are spatially confined to
flexible lipid membranes where, among other functions, they control cell
adhesion, motility and tissue formation. Besides being central to several
biological processes, \emph{multivalent interactions} mediated by reactive
linkers confined to deformable substrates underpin the design of
synthetic-biological platforms and advanced biomimetic materials. Here we
review recent advances on the experimental study and theoretical modelling of a
heterogeneous class of biomimetic systems in which synthetic linkers mediate
multivalent interactions between fluid and deformable colloidal units,
including lipid vesicles and emulsion droplets. Linkers are often prepared from
synthetic DNA nanostructures, enabling full programmability of the
thermodynamic and kinetic properties of their mutual interactions. The coupling
of the statistical effects of multivalent interactions with substrate fluidity
and deformability gives rise to a rich emerging phenomenology that, in the
context of self-assembled soft materials, has been shown to produce exotic
phase behaviour, stimuli-responsiveness, and kinetic programmability of the
self-assembly process. Applications to (synthetic) biology will also be
reviewed.Comment: 63 pages, revie
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