54,412 research outputs found
Message Flow Analysis with Complex Causal Links for Distributed ROS 2 Systems
Distributed robotic systems rely heavily on the publish-subscribe
communication paradigm and middleware frameworks that support it, such as the
Robot Operating System (ROS), to efficiently implement modular computation
graphs. The ROS 2 executor, a high-level task scheduler which handles ROS 2
messages, is a performance bottleneck. We extend ros2_tracing, a framework with
instrumentation and tools for real-time tracing of ROS 2, with the analysis and
visualization of the flow of messages across distributed ROS 2 systems. Our
method detects one-to-many and many-to-many causal links between input and
output messages, including indirect causal links through simple user-level
annotations. We validate our method on both synthetic and real robotic systems,
and demonstrate its low runtime overhead. Moreover, the underlying intermediate
execution representation database can be further leveraged to extract
additional metrics and high-level results. This can provide valuable timing and
scheduling information to further study and improve the ROS 2 executor as well
as optimize any ROS 2 system. The source code is available at:
https://github.com/christophebedard/ros2-message-flow-analysis.Comment: 14 pages, 12 figure
Civil aircraft advanced avionics architectures - an insight into saras avionics, present and future perspective
Traditionally, the avionics architectures being implemented are of federated nature, which means that each avionics function has its own independent, dedicated fault-tolerant computing resources. Federated architecture has great advantage of inherent fault containment and at the same time envelops a potential risk of massive use of resources resulting in increase in weight, looming, cost and maintenance as well. With the drastic advancement in the computer and software technologies, the aviation industry is gradually moving towards the use of Integrated Modular Avionics (IMA) for civil transport aircraft, potentially leading to multiple avionics functions housed in each hardware platform. Integrated Modular Avionics is the most important concept of avionics architecture for next generation aircrafts. SARAS avionics suite is purely federated with almost glass cockpit architecture complying to FAR25. The Avionics activities from the inception to execution are governed by the regulations and procedures under the review of Directorate General of Civil Aviation (DGCA). Every phase of avionics activity has got its own technically involvement to make the system perfect. In addition the flight data handling, monitoring and analysis is again a thrust area in the civil aviation industry leading to safety and reliability of the machine and the personnel involved. NAL has been in this area for more than two decades and continues to excel in these technologies
Do you see what I mean?
Visualizers, like logicians, have long been concerned with meaning. Generalizing from MacEachren's overview of cartography, visualizers have to think about how people extract meaning from pictures (psychophysics), what people understand from a picture (cognition), how pictures are imbued with meaning (semiotics), and how in some cases that meaning arises within a social and/or cultural context. If we think of the communication acts carried out in the visualization process further levels of meaning are suggested. Visualization begins when someone has data that they wish to explore and interpret; the data are encoded as input to a visualization system, which may in its turn interact with other systems to produce a representation. This is communicated back to the user(s), who have to assess this against their goals and knowledge, possibly leading to further cycles of activity. Each phase of this process involves communication between two parties. For this to succeed, those parties must share a common language with an agreed meaning. We offer the following three steps, in increasing order of formality: terminology (jargon), taxonomy (vocabulary), and ontology. Our argument in this article is that it's time to begin synthesizing the fragments and views into a level 3 model, an ontology of visualization. We also address why this should happen, what is already in place, how such an ontology might be constructed, and why now
Numerical simulation of the stress-strain state of the dental system
We present mathematical models, computational algorithms and software, which
can be used for prediction of results of prosthetic treatment. More interest
issue is biomechanics of the periodontal complex because any prosthesis is
accompanied by a risk of overloading the supporting elements. Such risk can be
avoided by the proper load distribution and prediction of stresses that occur
during the use of dentures. We developed the mathematical model of the
periodontal complex and its software implementation. This model is based on
linear elasticity theory and allows to calculate the stress and strain fields
in periodontal ligament and jawbone. The input parameters for the developed
model can be divided into two groups. The first group of parameters describes
the mechanical properties of periodontal ligament, teeth and jawbone (for
example, elasticity of periodontal ligament etc.). The second group
characterized the geometric properties of objects: the size of the teeth, their
spatial coordinates, the size of periodontal ligament etc. The mechanical
properties are the same for almost all, but the input of geometrical data is
complicated because of their individual characteristics. In this connection, we
develop algorithms and software for processing of images obtained by computed
tomography (CT) scanner and for constructing individual digital model of the
tooth-periodontal ligament-jawbone system of the patient. Integration of models
and algorithms described allows to carry out biomechanical analysis on
three-dimensional digital model and to select prosthesis design.Comment: 19 pages, 9 figure
Scientific Visualization Using the Flow Analysis Software Toolkit (FAST)
Over the past few years the Flow Analysis Software Toolkit (FAST) has matured into a useful tool for visualizing and analyzing scientific data on high-performance graphics workstations. Originally designed for visualizing the results of fluid dynamics research, FAST has demonstrated its flexibility by being used in several other areas of scientific research. These research areas include earth and space sciences, acid rain and ozone modelling, and automotive design, just to name a few. This paper describes the current status of FAST, including the basic concepts, architecture, existing functionality and features, and some of the known applications for which FAST is being used. A few of the applications, by both NASA and non-NASA agencies, are outlined in more detail. Described in the Outlines are the goals of each visualization project, the techniques or 'tricks' used lo produce the desired results, and custom modifications to FAST, if any, done to further enhance the analysis. Some of the future directions for FAST are also described
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