An experimental study of pressures on 60 deg Delta wings with leading edge vortex flaps

An experimental study was conducted in the Virginia Tech Stability Wind Tunnel to determine surface pressures over a 60 deg sweep delta wing with three vortex flap designs. Extensive pressure data was collected to provide a base data set for comparison with computational design codes and to allow a better understanding of the flow over vortex flaps. The results indicated that vortex flaps can be designed which will contain the leading edge vortex with no spillage onto the wing upper surface. However, the tests also showed that flaps designed without accounting for flap thickness will not be optimum and the result can be oversized flaps, early flap vortex reattachment and a second separation and vortex at the wing/flap hinge line

Pressure investigation of NASA leading edge vortex flaps on a 60 deg Delta wing

Pressure distributions on a 60 deg Delta Wing with NASA designed leading edge vortex flaps (LEVF) were found in order to provide more pressure data for LEVF and to help verify NASA computer codes used in designing these flaps. These flaps were intended to be optimized designs based on these computer codes. However, the pressure distributions show that the flaps wre not optimum for the size and deflection specified. A second drag-producing vortex forming over the wing indicated that the flap was too large for the specified deflection. Also, it became apparent that flap thickness has a possible effect on the reattachment location of the vortex. Research is continuing to determine proper flap size and deflection relationships that provide well-behaved flowfields and acceptable hinge-moment characteristics

Investigation of an aircraft trailing vortex using a tuft grid

With the increasing capacity of airport terminal areas, and the use of the new large jet transports, it has become important to understand the turbulent wake created by these aircraft. A study of the trailing vortex of a wing has been made using a tuft grid in a 6 foot wind tunnel. The study included an investigation of the use of mass injection at the wing tip as a means of destroying the vortex. Test results show that a fully developed, stable, vortex exists at least a distance of thirty chord lengths downstream of the wing, and that the swirl of the vortex can be reduced or eliminated by mass injection at the wing tip

PyPhi: A toolbox for integrated information theory

Integrated information theory provides a mathematical framework to fully characterize the cause-effect structure of a physical system. Here, we introduce PyPhi, a Python software package that implements this framework for causal analysis and unfolds the full cause-effect structure of discrete dynamical systems of binary elements. The software allows users to easily study these structures, serves as an up-to-date reference implementation of the formalisms of integrated information theory, and has been applied in research on complexity, emergence, and certain biological questions. We first provide an overview of the main algorithm and demonstrate PyPhi's functionality in the course of analyzing an example system, and then describe details of the algorithm's design and implementation. PyPhi can be installed with Python's package manager via the command 'pip install pyphi' on Linux and macOS systems equipped with Python 3.4 or higher. PyPhi is open-source and licensed under the GPLv3; the source code is hosted on GitHub at https://github.com/wmayner/pyphi . Comprehensive and continually-updated documentation is available at https://pyphi.readthedocs.io/ . The pyphi-users mailing list can be joined at https://groups.google.com/forum/#!forum/pyphi-users . A web-based graphical interface to the software is available at http://integratedinformationtheory.org/calculate.html .Comment: 22 pages, 4 figures, 6 pages of appendices. Supporting information "S1 Calculating Phi" can be found in the ancillary file

Multiple determinants of the productive use of the regular past tense suffix

We offer evidence that the productive use of English regular past tense morphology (e.g., drived) results from competitions among lexical-level features within a single mechanism associative system. W e present error data from: (1) on-line elicited productions by adult native speakers (N = 51), and (2) cormectionist back-propagation networks trained to map stems and past tenses of 552 English verbs. The frequency of regularizations is analyzed in terms of item frequency, stem final alveolar consonant, and similarity in past tense mapping across "friends" and "enemies" in phonologically defined neighborhoods. All items were compiled from a lexicon of 1,191 verbs which represents a near-exhaustive listing of monosyllabic stem-past tense pairs in current American English. Results revealed striking similarities between the hiunan and simulation data. Regularizations were significantly correlated with item frequency, as well as phonological attributes of the stem. Crucially, regularization was a function of phonological similarity to frequent suffixed items, especially for irregulars that normally undergo a vowel-change. These results are incompatible with the view that regularization applies by default, independently of inter-item similarities which support the acquisition and processing of lexical items in associative systems

Token Frequency and Phonological Predictability in a Pattern Association Network: Implications for Child Language Acquisition

The degree to which the behavior of PDP models of pattern associations (Rumelhart &McClelland, 1986; 1987) approximates children's acquisition of inflectional morphology has recently been highlighted in discussions of the applicability of P D P to the study of human cognition and language (Pinker & Mehler, 1988). In this paper, we attempt to eliminate many of the limitations of the R & M model, adopting an empirical approach to the analysis of learning(hit rate and error type) in two sets of simulations in which vocabulary structure (token frequency)and the presence of phonological subregularities are manipulated. A 3-layer back propagation network is used to implement a pattern association task with strings that are analogous to four types of present and past tense English verbs. W e overview resulting"competitions" when strings are randomly assigned to verb classes, in particular, the conditions under which different overgeneralization errors (both " pure" and " blended") are produced.In a second set of simulations, identical type and token frequencies are used, but strings are assigned to the identity and vowel change classes on the basis of phonological shape of the stem. Phonological cues are exploited by the system leading to overall improved performance.However, overgeneralizations continue to be observed in similar conditions. Token frequency works together with phonological subregularities to determine patterns of learning,including the conditions under which " rule-like"behavior will and will not emerge. The results are discussed with reference to behavioral data on children's acquisition of the English past tense

How much exposure to English is necessary for a bilingual toddler to perform like a monolingual peer in language tests?

Background Bilingual children are under-referred due to an ostensible expectation that they lag behind their monolingual peers in their English acquisition. The recommendations of the Royal College of Speech and Language Therapists (RCSLT) state that bilingual children should be assessed in both the languages known by the children. However, despite these recommendations, a majority of speech and language professionals report that they assess bilingual children only in English as bilingual children come from a wide array of language backgrounds and standardized language measures are not available for the majority of these. Moreover, even when such measures do exist, they are not tailored for bilingual children. Aims It was asked whether a cut-off exists in the proportion of exposure to English at which one should expect a bilingual toddler to perform as well as a monolingual on a test standardized for monolingual English-speaking children. Methods & Procedures Thirty-five bilingual 2;6-year-olds exposed to British English plus an additional language and 36 British monolingual toddlers were assessed on the auditory component of the Preschool Language Scale, British Picture Vocabulary Scale and an object-naming measure. All parents completed the Oxford Communicative Development Inventory (Oxford CDI) and an exposure questionnaire that assessed the proportion of English in the language input. Where the CDI existed in the bilingual's additional language, these data were also collected. Outcomes & Results Hierarchical regression analyses found the proportion of exposure to English to be the main predictor of the performance of bilingual toddlers. Bilingual toddlers who received 60% exposure to English or more performed like their monolingual peers on all measures. K-means cluster analyses and Levene variance tests confirmed the estimated English exposure cut-off at 60% for all language measures. Finally, for one additional language for which we had multiple participants, additional language CDI production scores were significantly inversely related to the amount of exposure to English. Conclusions & Implications Typically developing 2;6-year-olds who are bilingual in English and an additional language and who hear English 60% of the time or more, perform equivalently to their typically developing monolingual peers

Associated reading skills in children with a history of Specific Language Impairment (SLI)

A large cohort of 200 eleven-year-old children with Specific Language Impairment (SLI) were assessed on basic reading accuracy and on reading comprehension as well as language tasks. Reading skills were examined descriptively and in relation to early language and literacy factors. Using stepwise regression analyses in which age and nonverbal IQ were controlled for, it was found that a single word reading measure taken at 7 years was unsurprisingly a strong predictor of the two different types of reading ability. However, even with this measure included, a receptive syntax task (TROG) entered when reading accuracy score was the DV. Furthermore, a test of expressive syntax/narrative and a receptive syntax task completed at 7 years entered into the model for word reading accuracy. When early reading accuracy was excluded from the analyses, early phonological skills also entered as a predictor of both reading accuracy and comprehension at 11 years. The group of children with a history of SLI were then divided into those with no literacy difficulties at 11 and those with some persisting literacy impairment. Using stepwise logistic regression, and again controlling for IQ and age, 7 years receptive syntax score (but not tests of phonology, expressive vocabulary or expressive syntax/narrative) entered as a positive predictor of membership of the ‘no literacy problems’ group regardless of whether early reading accuracy was controlled for in step one. The findings are discussed in relation to the overlap of SLI and dyslexia and the long term sequelae of language impairment