133,269 research outputs found
Screen-shots of the TSP-H (top) and GEO-H (bottom) problem instances.
No full textScreen-shots of the TSP-H (top) and GEO-H (bottom) problem instances.</p
Making interactive TV easier to use : interface design for a second screen approach
No full textInteractive television (iTV) has the potential to revolutionize the way we consume broadcast media, but users still find both the notion of iTV and the services currently available problematic. This paper describes a project that investigates a representative group of users' aspirations, and barriers to iTV service engagement in the UK. This primary research informed the development of new User Interface (UI) and service solutions that addressed these barriers. Specifically, a second screen solution was developed to remove the need for iTV services to use on-screen graphics, dramatically improving the possibilities for effective interaction and navigation for iTV interfaces and services. The effectiveness of these solutions was evaluated through the testing of these new iTV services in a representative group of family homes
Axial Variations and Entry Effects in a Pressure Screen
No full textPressure screens are used for contaminant removal and fibre length fractionation in the production of pulp and paper products. Axial variations and entry effects in the screen are known to occur and these variations have not been adequately quantified. This thesis describes a fundamental study of the axial variations of several factors that occur within an industrial pressure screen; namely, pulp consistency, fibre length distribution, rotor pressure pulse, and feed annulus tangential velocity.
Axial variations of pulp consistency in the screen annulus and the accept chamber of the screen were studied using an internal radial sampling method. Localised pulp samples were taken and evaluated and common measures of screen performance such as fibre passage ratio and fractionation efficiency were calculated along the screen. Consistency generally increased along the length of the screen although under certain conditions the consistency toward the front of the screen was lower than the feed consistency. A two passage ratio model that incorporated forward and reverse passage ratio was derived to elucidate the flow of both fibre and fluid through the screen and their effects on overall screen performance. The passage of fibre through the screen decreased with screen length which generally had a positive effect on the fractionation efficiency toward the back of the screen. The passage of individual fibre length fractions was also studied and it was found that long fibre had a much lower passage than short fibre which caused the average fibre length in the annulus to increase.
Rotor induced pressure pulse variations along the screen length were also investigated. The magnitude of the pressure pulse was significantly lower (up to 40 %) at the rear of the screen. The variation in pressure caused by the rotor is due to a Venturi effect and the shape of the rotor. The relative velocity of the fluid and the rotor, called the slip factor, also directly affects the size of the pressure pulse in the annulus. The slip factor decreases along the length of the screen due to the increase in tangential velocity of the fluid. Pressure pulse data was also used to estimate the instantaneous aperture velocity and back-flush ratio. The instantaneous aperture velocity was calculated to vary considerably from the superficial aperture velocity by up to 5 m/s in the forward direction and 10 m/s in the reverse direction.
Computational Fluid Dynamics (CFD) was used to model tangential velocity changes in simplified screen annuli with axial through flow. For a smooth screen rotor the mean tangential velocity increased over the entire length of the annulus without reaching a maximum value. A step and bump rotor were modelled and the shape of the pressure pulses showed good agreement with experimentally measured pulses. The mean tangential velocity and the entrance length were found to be heavily dependant on the screen rotor used
The principles of screen design for computer-based learning materials.
No full textThe critical interface between learners and computer-based learning materials is the
screen. If the display of learning is not effective then learning will be hindered.
Screen design is therefore an important element in the design of computer-based
learning.
This research investigated the three fundamental screen design elements of
text, colour and graphics. A review of literature, experimental design and a limited
survey of computer-based learning materials provided the background for this
research. The experimental materials reflected the results of the review and survey
by using representative subjects, providing a learning focus and employing computerbased materials. Two experiments were undertaken. The Colour and Graphics
experiments considered the effects of a number of variables on learners' behaviour
which included: the use of colour; the size and type of graphics; the learner's prior
knowledge of tutorial subject; and the complexity of the display.
The results of this research showed that colour is a powerful motivating force
as long as it is not used excessively. This was identified as the use of more than
seven colours. Graphics can be used more extensively in current computer-based
learning materials and users preferred representational graphics occupying a quarter
to a half of the screen. However, learners were not prepared to make the effort to
either use analogical graphics to make links with their prior knowledge or to extract
information contained in the structure and form of logical graphics. Subjects were
motivated by representational graphics.
Learners' behaviour in relation to the various screen displays they
encountered was affected by their prior knowledge of the tutorial content. This was
apparent in their choice of options (additional modules) within the tutorial, their
methods of interacting with the material and their responses to individual displays
Electrochemical characterization of commercial and home-made screen-printed carbon electrodes
No full textScreen-printing technology is widely used for the mass-production of
disposable electrochemical sensors. The practical utility of carbon
screen-printed electrodes has been exploited, despite the fact that
little is known about the nature of the electrode reactions.
(Wang, J.; Pedrero, M.; Sakslumd, H.; Hammerich, O.; Pingarron, J.
Electrochemical activation of screenprinted carbon strips. The
Analyst 1996, 121 (3), 345–350). Given the complexity of carbon
electrodesin general, and differences in the composition of commercial
carbon inks, the question arises as to how such differences and
complexity affect their electrochemical reactivity. The aim of this work wasto compare the electroactivity of both commercial electrodesand
electrodes fabricated in-house from various commercial
inks, in order to find the electrode most suited to amperometric
sensor work. Methods of analysis include cyclic voltammetry,
amperometry and linear sweep voltammetry. It was found that the
commercial working electrodeswere not suited to the high current
work of interest, due to their poor charge transfer properties. The
in-house electrode had less resistive properties, and was more suited
for high current amperometric sensing. Utilizing this electrode
configuration, an optimal carbon paste was chosen for the working
electrode
Screen printed layers of cds for solar cells
No full textIt is generally accepted nowadays that a significant cost reduction in terrestrial solar cell application could be brought about by investigating alternative fabrication techniques for solar cells. It is believed that screen printing (or the so called thick film technique) is one such technique which promises a potentially low cost method for fabricating flexible, large area solar energy conversion cells. The active research on this technique started in 1976 in Japan. However, it was not until 1983, that wide interest developed when the Matsushita group in Japan reported an efficiency of 12.8% for their entirely screen printed CdS/CdTe solar cells. This was the highest reported efficiency for any thin film solar cell. However, the details of the fabrication processes of these cells were not reported and several scientific groups in the world started to explore this technique. The first published report was in 1985. In the last few years these groups have reported results on various aspects of this technique. Nevertheless there are still major parameters to be investigated. This thesis represents a concise reference for the application of the screen printing technique to solar cells. In the course of this study many new investigations have been made which supplement the previous work by other groups. Starting with a pure CdS powder with suitable grain size and distribution is a prerequisite for achieving the best morphological and electrical behaviour of screen printed layers of CdS. Careful paste mixing is of uppermost importance which can override any other parameters involved in the fabrication processes. It is essential to impose restricted sintering conditions for adequate utilization of the doping and fluxing function of the CdCl(_2) material. Standardization of the printing, preparation and sintering conditions involved in the fabrication processes were necessary to ensure reproducible CdS layers. Good quality screen printed layers were fabricated on soda lime substrates. The significance of other substrate materials for CdS preparation was also investigated and optimum substrate choice is suggested. The properties of the CdS screen printed layers were investigated by forming simple Schottky devices and more complicated heterojunction solar cells. Good rectification behaviour of the Schottky diodes was achieved. The CdS/CdTe solar cells revealed a wide spectral response. However, the photovoltaic behaviour was relatively poor largely due to the high resistivity of the CdTe part of the cell structure
Screen Printed PZT Composite Thick Films
No full textComposite film (ComFi) technology has been developed as an alternative technique to achieve thick (5–100 ?m) films at temperatures compatible with silicon processing. The technique entails producing a composite slurry consisting of PZT powder and a PZT producing sol. The slurry is then deposited onto the substrate, dried and fired at 710°C. Intermediate sol infiltration and pyrolysis can be used to increase the density and improve the functional properties of the films. A slurry suitable for screen printing has been developed and used to print PZT thick films. The dielectric and piezoelectric properties of the screen printed material are presented. Material properties of the screen printed ComFi material were found to be comparable to, or exceeded, those observed in traditional screen printed materials
Screen reading habits among university students
No full textAbstractAmong the numerous areas of education which have been impacted by technology, the growth of reading texts from computer screens is one of the most widespread. This trend is perhaps most evident at universities with academic journal articles increasing being stored and accessed in this format. As with any technological changes, the spread of screen reading presents educators and students with a range of challenges and opportunities. This paper seeks to examine the general preferences and habits of university students when reading academic articles, specifically their use of annotations and other means of interacting with a text. An on-line survey was conducted and the views of 630 students analyzed. The data reveals several tensions in the preferences and habits of these students and suggests that a knowledge gap may exist which could hamper their ability to interact with digital texts. The article ends with a syllabus outline for an academic reading course for non-native speakers (NNS) and suggestions for further research in the area
Development and application of the phase-screen seismic modelling code
No full textAs a consequence of the aims of this project, this thesis is divided into two distinct sections. Initially, the computationally efficient phase-screen forward modelling technique is extended to allow investigation of non-normal ray paths. The code is developed to accommodate all diffracted and converted phases up to critical angle, building on a geometrical construction method previously developed with a narrow-angle approximation. The new approach relies upon pre-scanning the model space to assess the complexity of each screen. The propagating wavefields are then divided as a function of horizontal wavenumber, and each subset is transformed to the spatial domain separately, carrying with it angular information. This allows both locally accurate 3D phase corrections and Zoeppritz reflection and transmission coefficients to be applied. The phase-screen code is further developed to handle simple anisotropic media. During phase-screen modelling, propagation is undertaken in the wavenumber domain where exact expressions for anisotropic phase velocities are incorporated. Extensive testing of the enhanced phase-screen technique includes simple analytical models to justify the inclusion of multiple energy alongside synthetic examples from models commonly used to test numerical modelling techniques. Additionally the code is tested with real models from a producing field in a marine sedimentary location where an exhaustive range of geophysical techniques were used to constrain the VTI parameters. Secondly within this thesis, the narrow angle version of the phase-screen method is used to generate a comprehensive pre-stack seismic reflection dataset for our industrial partners. Current exploration within the European oil and gas community is heavily focused on regions where the targets for production are positioned beneath plateau basalts oh the north west European margin. These environments produce a complex seismic response due to the scattering generated by the internal composition of the basalt flows. This study generates a large subsurface volume, derived from geological mapping projects in the Hold-with-Hope region of north east Greenland, and synthetically acquires a realistic 3-D reflection study across it. The basalt is uniquely generated as a single random volume with distinct correlation lengths in each orthogonal direction and a novel approach to determine seismic attenuation through basalts is developed. Initial results from this data set are presented after careful optimisation of the modelling code and parameters
Bronze Screen Chicana and Chicano Film Culture
No full textExplores Chicana and Chicano popular culture through contemporary representations in both Hollywood commercial and independent cinema.Rosa Linda Fregoso's The Bronze Screen opens the way for international debate on the new critical field of Chicano/a cinema. Fregoso provides an incisive articulation of the ways in which narrative codes in film can telescope complex versions of Mexican and American culture and history. The often violent impact of 'first' (U.S.) and 'third' (Mexico) world cultures and geographies is channeled through the very term Chicano/a as well as its cinematic representation. Fregoso's masterful critique brings out with great clarity the irony, paradox, and contradictions of such historical collisions. --Norma Alarcón, University of California, Berkeley.Intro -- Contents -- List of Photographs -- Acknowledgments -- Introduction: The Bronze Screen: Looking at Us Looking -- 1 Actos of "Imaginative Re-discovery -- 2 Intertextuality and Cultural Identity in Zoot Suit (1981) and La Bamba (1987) -- 3 Humor as Subversive De-construction: Born in East L.A. (1987) -- 4 From Il(l)egal to Legal Subject: Border Construction and Re-construction -- 5 Nepantla in Gendered Subjectivity -- 6 Conclusion: Eastside Story Re-visited -- Notes -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- U -- V -- W -- Y -- ZExplores Chicana and Chicano popular culture through contemporary representations in both Hollywood commercial and independent cinema.Rosa Linda Fregoso's The Bronze Screen opens the way for international debate on the new critical field of Chicano/a cinema. Fregoso provides an incisive articulation of the ways in which narrative codes in film can telescope complex versions of Mexican and American culture and history. The often violent impact of 'first' (U.S.) and 'third' (Mexico) world cultures and geographies is channeled through the very term Chicano/a as well as its cinematic representation. Fregoso's masterful critique brings out with great clarity the irony, paradox, and contradictions of such historical collisions. --Norma Alarcón, University of California, Berkeley.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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