14,809 research outputs found
A conceptual framework for using Doppler radar acquired atmospheric data for flight simulation
A concept is presented which can permit turbulence simulation in the vicinity of microbursts. The method involves a large data base, but should be fast enough for use with flight simulators. The model permits any pilot to simulate any flight maneuver in any aircraft. The model simulates a wind field with three-component mean winds and three-component turbulent gusts, and gust variation over the body of an aircraft so that all aerodynamic loads and moments can be calculated. The time and space variation of mean winds and turbulent intensities associated with a particular atmospheric phenomenon such as a microburst is used in the model. In fact, Doppler radar data such as provided by JAWS is uniquely suited for use with the proposed model. The concept is completely general and is not restricted to microburst studies. Reentry and flight in terrestrial or planetary atmospheres could be realistically simulated if supporting data of sufficient resolution were available
Biosignals as an Advanced Man-Machine Interface
As is known for centuries, humans exhibit an electrical profile. This profile is altered through various physiological processes, which can be measured through biosignals; e.g., electromyography (EMG) and electrodermal activity (EDA). These biosignals can reveal our emotions and, as such, can serve as an advanced man-machine interface (MMI) for empathic consumer products. However, such an MMI requires the correct classification of biosignals to emotion classes. This paper explores the use of EDA and three facial EMG signals to determine neutral, positive, negative, and mixed emotions, using recordings of 24 people. A range of techniques is tested, which resulted in a generic framework for automated emotion classification with up to 61.31% correct classification of the four emotion classes, without the need of personal profiles. Among various other directives for future research, the results emphasize the need for both personalized biosignal-profiles and the recording of multiple biosignals in parallel
Artificial Intellignce: Art or Science?
Computer programs are new kinds of machines with great potential for improving the quality of life. In particular, expert systems could improve the ability of the small, weak and poor members of society to access the information they need to solve their problems. However, like most areas of computing, expert systems design is currently practiced as an art. In order to realise its potential it must also become an engineering science: providing the kinds of assurances of reliability that are normal in other branches of engineering. The way to do this is to put the techniques used to build expert systems and other artificial intelligence programs onto a sound theoretical foundation. The tools of mathematical logic appear to be a good basis for doing this, but we need to be imaginative in their use-not restricting ourselves to the kind of deductive reasoning usually thought of as 'logical', but investigating other aspects of reasoning, including uncertain reasoning, making conjectures and the guidance of inference. Acknow ledgement
Feature subset selection: a correlation based filter approach
Recent work has shown that feature subset selection can have a position affect on the performance of machine learning algorithms. Some algorithms can be slowed or their performance adversely affected by too much data some of which may be irrelevant or redundant to the learning task. Feature subset selection, then, is a method of enhancing the performance of learning algorithms, reducing the hypothesis search space, and, in some cases, reducing the storage requirement. This paper describes a feature subset selector that uses a correlation based heuristic to determine the goodness of feature subsets, and evaluates its effectiveness with three common ML algorithms: a decision tree inducer (C4.5), a naive Bayes classifier, and an instance based learner(IBI). Experiments using a number of standard data sets drawn from real and artificial domains are presented. Feature subset selection gave significant improvement for all three algorithms; C4.5 generated smaller decision trees
Deriving consensus rankings via multicriteria decision making methodology
Purpose - This paper seeks to take a cautionary stance to the impact of the
marketing mix on customer satisfaction, via a case study deriving consensus
rankings for benchmarking on selected retail stores in Malaysia.
Design/methodology/approach - The ELECTRE I model is used in deriving
consensus rankings via multicriteria decision making method for benchmarking
base on the marketing mix model 4P's. Descriptive analysis is used to analyze
best practice among the four marketing tactics.
Findings - Outranking methods in consequence constitute a strong base on
which to found the entire structure of the behavioral theory of benchmarking
applied to development of marketing strategy.
Research limitations/implications - This study looks only at a limited part
of the puzzle of how consumer satisfaction translates into behavioral outcomes.
Practical implications - The study provides managers with guidance on how to
generate a rough outline of potential marketing activities that can be used to
take advantage of capabilities and convert weaknesses and threats.
Originality/value - The paper interestingly portrays the effective usage of
multicriteria decision-making and ranking method to help marketing managers
predict their marketing trends
Spatially Adiabatic Frequency Conversion in Optoelectromechanical Arrays
Faithful conversion of quantum signals between microwave and optical
frequency domains is crucial for building quantum networks based on
superconducting circuits. Optoelectromechanical systems, in which microwave and
optical cavity modes are coupled to a common mechanical oscillator, are a
promising route towards this goal. In these systems, efficient, low-noise
conversion is possible using a mechanically dark mode of the fields but the
conversion bandwidth is limited to a fraction of the cavity linewidth. Here, we
show that an array of optoelectromechanical transducers can overcome this
limitation and reach a bandwidth that is larger than the cavity linewidth. The
coupling rates are varied in space throughout the array so that the
mechanically dark mode of the propagating fields adiabatically changes from
microwave to optical or vice versa. This strategy also leads to significantly
reduced thermal noise with the collective optomechanical cooperativity being
the relevant figure of merit. Finally, we demonstrate that, quite surprisingly,
the bandwidth enhancement per transducer element is largest for small arrays;
this feature makes our scheme particularly attractive for state-of-the-art
experimental setups.Comment: 18 pages, 10 figures (including Supplemental Material
Amplitude variability and multiple frequencies in 44 Tau: 2000 - 2006
This study has three principal aims: (i) to increase the number of detected
pulsation modes of 44 Tau, especially outside the previously known frequency
ranges, (ii) to study the amplitude variability and its systematics, and (iii)
to examine the combination frequencies.
During the 2004/5 and 2005/6 observing seasons, high-precision photometry was
obtained with the Vienna Automatic Photoelectric Telescope in Arizona during 52
nights. Together with previous campaigns, a data base from 2000 to 2006 was
available for multifrequency analyses.
Forty-nine pulsation frequencies are detected, of which 15 are independent
pulsation modes and 34 combination frequencies or harmonics. The newly found
gravity mode at 5.30 c/d extends the known frequency range of instability.
Strong amplitude variability from year to year is found for the \ell = 1 modes,
while the two radial modes have essentially constant amplitudes. Possible
origins of the amplitude variability of the \ell = 1 modes, such as precession
of the pulsation axis, beating and resonance effects are considered. The
amplitudes of the combination frequencies, f_i + f_j, mirror the variations in
the parent modes. The combination parameter, which relates the amplitudes of
the combination frequencies to those of the parent modes, is found to be
different for different parents.Comment: 10 pages, 8 figures, 4 tables, accepted for publication in A&
Overview of NASA's programs
An overview of some of NASA's aviation related programs is presented. The areas discussed include: (1) severe storms; (2) clear air turbulence; (3) icing; (4) fog; and (5) landing systems
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