7,053 research outputs found
Performance of a J85-13 compressor with clean and distorted inlet flow
The results presented are of a series of experimental tests in which a J85-13 turbojet engine was subjected to both distorted and undistorted inlet total pressure conditions. A distinctive feature of the data base obtained is that it includes compressor interstage information not previously recorded for a J85-13 engine. Each of the eight compressor stages was instrumented to obtain the characteristics of the individual stages for undistorted inlet conditions, and these data are documented in the report along with the undistorted compressor overall performance. Also included in the report is the overall performance of the compressor exposed to 14 different distorted-inlet conditions - 10 circumferential patterns and 4 radial patterns. The distortion patterns were introduced using screens that spoiled from 8 to 50 percent of the compressor face area; the distortion screen density, or the area blocked by the screen wire per unit area of screen, varied from 26 to 69 percent
Frequency response of an axial-flow compressor exposed to inlet pressure perturbations
Experimental results of a series of engine tests designed to obtain the stage dynamics of an eight-stage axial-flow compressor over the frequency range of 0.5 to 200 hertz are presented. The total pressure at the compressor face was varied by means of a secondary air jet system installed in the engine inlet and positioned to oppose the primary airflow. Total-pressure probes located at each compressor stage were used to obtain the frequency response of each compressor-stage total pressure to the average compressor-inlet total pressure. The engine operating conditions were chosen to illustrate the effects of changing the rotor speed, changing the exhaust nozzle area, and isolating the compressor discharge pressure perturbations from the fuel control and hence, the fuel flow
Embedding generic employability skills in an accounting degree: development and impediments
This paper explores and analyses the views of, and effects on, students of a project that integrated the development of employability skills within the small group classes of two compulsory courses in the first year of an accounting degree at a UK university. The project aimed to build, deliver and evaluate course materials designed to encourage the development of a broad range of employability skills: skills needed for life-long learning and a successful business career. By analysing students' opinions gathered from a series of focus groups spread throughout the year, three prominent skill areas of interest were identified: time management, modelling, and learning to learn. Further analysis highlighted the complex nature of skills development, and brought to light a range of impediments and barriers to both students' development of employability skills and their subject learning. The analysis suggests the need for accounting educators to see skills development as being an essential element of the path to providing a successful accounting education experience
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Systems and methods for altering visual acuity
Provided are systems operable to effect a temporary change in a modulation transfer function (MTF) of a target imaging system. The systems include a light source operable to produce light for transient propagation onto at least a portion of the target imaging system, a power source in operative communication with the light source and configured to effect the production of light from the light source, and a transmission unit in operative communication with the light source and configured to propagate the produced light onto at least a portion of the target imaging system. The propagated light is configured for absorbance by the portion of the target imaging system; the absorbance causes an increase in temperature and a change in a refractive index profile of at least the portion of the imaging system. The change in refractive index profile produces a temporary change in the MTF of the imaging system.Board of Regents, University of Texas Syste
Graphical Encoding of a Spatial Logic for the pi-Calculus
This paper extends our graph-based approach to the verification of spatial properties of π-calculus specifications. The mechanism is based on an encoding for mobile calculi where each process is mapped into a graph (with interfaces) such that the denotation is fully abstract with respect to the usual structural congruence, i.e., two processes are equivalent exactly when the corresponding encodings yield isomorphic graphs. Behavioral and structural properties of π-calculus processes expressed in a spatial logic can then be verified on the graphical encoding of a process rather than on its textual representation. In this paper we introduce a modal logic for graphs and define a translation of spatial formulae such that a process verifies a spatial formula exactly when its graphical representation verifies the translated modal graph formula
Effective representation of RT-LOTOS terms by finite time petri nets
The paper describes a transformational approach for the
specification and formal verification of concurrent and real-time systems. At upper level, one system is specified using the timed process algebra RT-LOTOS. The output of the proposed transformation is a Time Petri net (TPN). The paper particularly shows how a TPN can be automatically constructed from an RT-LOTOS specification using a compositionally defined mapping. The proof of the translation consistency is sketched in the paper and developed in [1]. The RT-LOTOS to TPN translation patterns formalized in the paper are being implemented. in a prototype tool. This enables reusing TPNs verification techniques and tools for the profit of RT-LOTOS
Higher physical fitness levels are associated with less language decline in healthy ageing
Healthy ageing is associated with decline in cognitive abilities such as
language. Aerobic fitness has been shown to ameliorate decline in some
cognitive domains, but the potential benefits for language have not been
examined. In a cross-sectional sample, we investigated the relationship between
aerobic fitness and tip-of-the-tongue states. These are among the most frequent
cognitive failures in healthy older adults and occur when a speaker knows a
word but is unable to produce it. We found that healthy older adults indeed
experience more tip-of-the-tongue states than young adults. Importantly, higher
aerobic fitness levels decrease the probability of experiencing
tip-of-the-tongue states in healthy older adults. Fitness-related differences
in word finding abilities are observed over and above effects of age. This is
the first demonstration of a link between aerobic fitness and language
functioning in healthy older adults
Process algebra modelling styles for biomolecular processes
We investigate how biomolecular processes are modelled in process algebras, focussing on chemical reactions. We consider various modelling styles and how design decisions made in the definition of the process algebra have an impact on how a modelling style can be applied. Our goal is to highlight the often implicit choices that modellers make in choosing a formalism, and illustrate, through the use of examples, how this can affect expressability as well as the type and complexity of the analysis that can be performed
BigraphER: rewriting and analysis engine for bigraphs
BigraphER is a suite of open-source tools providing an effi-
cient implementation of rewriting, simulation, and visualisation for bigraphs,
a universal formalism for modelling interacting systems that
evolve in time and space and first introduced by Milner. BigraphER consists
of an OCaml library that provides programming interfaces for the
manipulation of bigraphs, their constituents and reaction rules, and a
command-line tool capable of simulating Bigraphical Reactive Systems
(BRSs) and computing their transition systems. Other features are native
support for both bigraphs and bigraphs with sharing, stochastic reaction
rules, rule priorities, instantiation maps, parameterised controls, predicate
checking, graphical output and integration with the probabilistic
model checker PRISM
Linguistics
Contains reports on four research projects.National Institutes of Health (Grant MH-13390-01U. S. Air Force (Electronic Systems Division) under Contract AF 19(628)-248
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