55 research outputs found
IRAC Full-Scale Flight Testbed Capabilities
Overview: Provide validation of adaptive control law concepts through full scale flight evaluation in a representative avionics architecture. Develop an understanding of aircraft dynamics of current vehicles in damaged and upset conditions Real-world conditions include: a) Turbulence, sensor noise, feedback biases; and b) Coupling between pilot and adaptive system. Simulated damage includes 1) "B" matrix (surface) failures; and 2) "A" matrix failures. Evaluate robustness of control systems to anticipated and unanticipated failures
A framework for the local information dynamics of distributed computation in complex systems
The nature of distributed computation has often been described in terms of
the component operations of universal computation: information storage,
transfer and modification. We review the first complete framework that
quantifies each of these individual information dynamics on a local scale
within a system, and describes the manner in which they interact to create
non-trivial computation where "the whole is greater than the sum of the parts".
We describe the application of the framework to cellular automata, a simple yet
powerful model of distributed computation. This is an important application,
because the framework is the first to provide quantitative evidence for several
important conjectures about distributed computation in cellular automata: that
blinkers embody information storage, particles are information transfer agents,
and particle collisions are information modification events. The framework is
also shown to contrast the computations conducted by several well-known
cellular automata, highlighting the importance of information coherence in
complex computation. The results reviewed here provide important quantitative
insights into the fundamental nature of distributed computation and the
dynamics of complex systems, as well as impetus for the framework to be applied
to the analysis and design of other systems.Comment: 44 pages, 8 figure
Emergency resuscitative thoracotomy performed in European civilian trauma patients with blunt or penetrating injuries: a systematic review
Continuous-time modeling of cell fate determination in Arabidopsis flowers
<p>Abstract</p> <p>Background</p> <p>The genetic control of floral organ specification is currently being investigated by various approaches, both experimentally and through modeling. Models and simulations have mostly involved boolean or related methods, and so far a quantitative, continuous-time approach has not been explored.</p> <p>Results</p> <p>We propose an ordinary differential equation (ODE) model that describes the gene expression dynamics of a gene regulatory network that controls floral organ formation in the model plant <it>Arabidopsis thaliana</it>. In this model, the dimerization of MADS-box transcription factors is incorporated explicitly. The unknown parameters are estimated from (known) experimental expression data. The model is validated by simulation studies of known mutant plants.</p> <p>Conclusions</p> <p>The proposed model gives realistic predictions with respect to independent mutation data. A simulation study is carried out to predict the effects of a new type of mutation that has so far not been made in <it>Arabidopsis</it>, but that could be used as a severe test of the validity of the model. According to our predictions, the role of dimers is surprisingly important. Moreover, the functional loss of any dimer leads to one or more phenotypic alterations.</p
Computational mechanics and information measures in food webs
In this study we reconstruct predator-prey relationships from biomass time series of a simulated system of interacting species. To overcome the shortcomings of a static food webs representation we introduce a new model which accounts for both population and interaction dynamics. It is a derived version of the light-cone model from special relativity theory. To identify the existence of predator–prey relationships in the system we quantify the notion of distance in a food web. We use known measures from information theory, namely mutual information and transfer entropy, and we introduce a new measure based on causal states of point and patch predictors. To evaluate our results we compare the distances measured with a minimum distance measure from the underlying food web, and examine the accuracy of the measures in inferring the existence of the actual predator–prey relationships. First results show that our new measure based on causal states of point and patch predictors together with the transfer entrop
Deterministic inference for stochastic systems using multiple shooting and a linear noise approximation for the transition probabilities
Corporate Social Responsibilities among Oil Extracting Multinational Companiess in Least Developing Countries: Helping but Not Developing or Helping and Developing?
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