25,995 research outputs found
Using performance assessment in secondary school mathematics: an empirical study in a Singapore classroom
No full textThis article reports an exploratory study on using performance assessment in mathematics instruction in a high-performing secondary school in Singapore. An intact mathematics class participated in the study, and received chapter-based performance tasks as intervention during regular mathematics lessons for about one and a half school years. The performance tasks used included authentic and/or open-ended tasks. The students’ academic achievements and attitudes in mathematics were compared with a comparison class that did not receive the intervention. Both quantitative and qualitative data were collected, mainly through questionnaire surveys, performance task tests, conventional school exams, and interviews with students and teachers. The results suggest that the students receiving the intervention performed significantly better than their counterparts in solving conventional exam problems, and in general they also showed more positive changes in attitudes towards mathematics and mathematics learning. The students from the experimental class also expressed positive views about the benefits of using performance tasks in promoting their ability in higher order thinking, though no statistically significant difference was detected between the two classes of students in solving unconventional tasks before and after intervention. Overall, the results appear to support teachers’ using contextualised problems in real life situations and open-ended investigations in students’ learning of mathematic
Apocaligonellidus nom. nov. for Echinopsis Fan & Chen, 1996, preoccupied (Acari: Prostigmata: Raphignathoidea: Xenocaligonellididae)
No full textFAN, Q.-H., CHEN, Y. (2008): Apocaligonellidus nom. nov. for Echinopsis Fan & Chen, 1996, preoccupied (Acari: Prostigmata: Raphignathoidea: Xenocaligonellididae). Zootaxa 1717 (1): 68, DOI: 10.11646/zootaxa.1717.1.6, URL: http://dx.doi.org/10.11646/zootaxa.1717.1.
Richardson, Barbauld, and the construction of an early modern fan club
No full textMPhilMuch has been written about the life and long works of the eighteenth century epistolary novelist, Samuel Richardson, but the prospect of his position as the first celebrity novelist – responsible for courting his own fame as well as initiating his own fan club – has largely been ignored. The body of manuscripts housed at the National Art Library in the Victoria and Albert Museum in London provides the modern scholar with evidence of the skeletal beginnings of an early fan club. This thesis aims to show how these manuscripts were turned into a saleable commodity by the publisher and entrepreneur Richard Phillips, while under the guiding hand of another, slightly later, literary celebrity, Anna Laetitia Barbauld. In order to restore Richardson’s reputation amongst a new nineteenth century audience, Barbauld was required to construct her own idea of him as an eighteenth century celebrity author, and in doing so the insecurities of a self-professed, apparently diffident man, are revealed. Barbauld’s capacious, but heavily edited selection of letters is analyzed in this thesis, providing ample evidence that Richardson’s correspondents were more than just eager letter writers. By using Barbauld’s biography of Richardson this thesis aims to show how she manipulates the genre of life writing in her construction of him.
This thesis offers an alternative reading of how the Richardson manuscripts are viewed, redefining them as not simply a collection of letters, but as a collective entity, deliberately selected and archived as evidence of an early modern fan club, and its celebrity managing director
Going beyond on-pitch success: fan engagement as a catalyst for growth
No full textThis research investigates the case of fan engagement as a strategy for long-term growth for football clubs. Through an exploratory methodology this study gains a
valuable insight into the current perceptions and usage of fan engagement, with a particular focus on social media.
Whilst the subject of social media is
growing in academic journals, there is very
little understanding of how sport organisations are
using this platform. 14 semi-structured interviews with key industry personnel and a fan focus group in addition to a content analysis of the Twitter feeds of 10 Premier
League football clubs was undertaken to offer new insight to the academic conversation in this subject area. The research findings suggest that
clubs need to develop ways to build and create long-term loyalty through fan engagement in
preference to unsustainable growth strategies based exclusively on winning and on-pitch performance.
Since winning is only possible for a select few every season, a strategy that places the fan at the centre of the club will prove beneficial to most clubs at all levels in the long term.
With the incoming financial controls being
implemented across the English football leagues in addition to UEFA’s Financial Fair Play legislation, the
significance of developing long-term profitability has never been more evident.
Those clubs which place Customer Relationship Management (CRM) as an overriding philosophy throughout the organisation and develop social media platforms effectively as part of a CRM strategy are best placed to improve their
understanding of fans and adapt their marketing strategies
to build loyalty and advocacy to the brand, which in time will deliver profitability and long-term growth
Development of a rotor model for the numerical simulation of helicopter exterior flow-fields
No full textIncludes bibliographical references (leaves 84-85).A numerical methodology is developed to model the effect of a rotor on the surrounding flow-field. The model calculates the time-averaged aerodynamic forces exerted on the air by the fan blades within the blade-swept region, and permits the user to specify blade properties such as cross-sectional profile and orientation at a particular radial and azimuthal location. The calculated forces are included as source terms within the Reynolds-averaged Navier-Stokes equations for an incompressible fluid, which are solved by the commercial CFD solver, FLUENT. The effects of turbulence are incorporated through the use of Launder and Spalding's k-g turbulence model. This method is selected as being the most efficient use of the resources available, giving the economic advantages of a steady simulation, while allowing radial and azimuthal variations of rotor characteristics. In order to validate the accuracy of the numerical model for both aligned and non-aligned inflow conditions, results are compared with experimental data reported for an axial flow fan. Agreement between experimental and numerical results is excellent to good. Fan static pressure rise is closely predicted by the numerical solution, while fan power consumption and fan static efficiency are under and over-predicted respectively. This error may be attributed to frictional losses not accounted for in the numerical model. These include physical rotational instabilities, leading to increased mechanical losses, and tip effects due to the clearance between the fan blade tips and the fan casing. Trends are nevertheless consistently predicted by the numerical model for inflow angles up to 45°, and for the range of blade pitch settings used. The adverse effect of off-axis inflow on the fan static pressure rise is numerically predicted, while fan power consumption is found to remain independent of inflow angle, as had been experimentally observed. The rotor model is finally integrated with the fuselage of the CIRSTEL (Combined Infra-Red Suppression and Tail rotor Elimination) prototype in an analysis of the helicopter exterior flow-field. No experimental data for this configuration was available for validation purposes. However, the model is used in the simulation of several common helicopter flight conditions. Results are presented graphically, and generally indicate good agreement with physically observed phenomena
A Q-learning based multi-strategy integrated artificial bee colony algorithm with application in unmanned vehicle path planning
No full textArtificial bee colony (ABC) is a prominent algorithm that offers great exploration capabilities among various meta-heuristic algorithms. However, its monotonous and one-dimensional search strategy limits its searching performance in the solving process. Thus, to address this issue, a Q-learning based multi-strategy integrated ABC algorithm (QMABC) is proposed. In the QMABC, multiple search strategies are proposed to utilize different individual experiences and search approaches for solution updates. Then, Q-learning is employed for strategy selection. In comparison to previous studies, this paper introduces more effective state and action configurations within the framework of Q-learning. To evaluate the performance of the QMABC, CEC 2017 benchmark functions are adopted to compare it to different meta-heuristic algorithms including ABC based and non-ABC based algorithms. Moreover, applications in path planning are implemented to further verify the effectiveness of the QMABC. Overall, it should be highlighted that the proposed QMABC demonstrates superiority in both numerical and practical experiments.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Discrete Mathematics and Optimizatio
The performance and application of cross flow fans for automotive engine cooling systems
No full textThe work reported centres on the application of cross flow fan units to provide forced air flow over the radiator used for engine cooling. It is shown that a cooling system in which the airflow is ducted through the vehicle would lead to a significant reduction in vehicle drag. A ducted system allows more exact prediction of performance, and can be more easily designed in conjunction with across flow fan, that has rectangular inlet and outlet sections, and an ability to form 'S', 'L' and 'U' airflow geometries. This shape advantage of the cross flow fan also allows the use of radiators with a higher aspect ratio that could in turn permit lower bonnet lines on vehicles with a further reduction in aerodynamic drag. At higher vehicle speeds adequate cooling is usually provided by ram airflow through the cooling system. An airflow by-pass arrangement controlled by a balance valve has been devised and tested. The operation of this valve was found to be stable and smooth, and extremely beneficial in reducing the total system resistance and increasing fan performance under ram airflow conditions. A computer model has been developed and a programme produced to facilitate matching of the air circuit, fan and motor. Examples illustrate the use of this in the design of a system for a 1,6 litre passenger vehicle, with maximum b.h.p. in second gear being taken as the most critical engine condition for cooling performance
Fan Noise Boundary Layer Ingestion Installation Effects for NOVA Aircraft Configuration
No full textAim of this paper is to investigate the effects of the turbulent flow developing over a fuselage on fan noise for Boundary Layer Ingestion (BLI) embedded propulsion systems. Such engine configurations can suffer from inlet flow distortions and ingestion of turbulence at the fan plane with consequent impact on both broadband and tonal fan noise. The analysis is performed by considering a modified version of the Low-Noise configuration of the NASA Source Diagnostic Test (SDT) integrated into the Nextgen ONERA Versatile Aircraft (NOVA) fuselage in order to reproduce the NOVA BLI configuration. The numerical flow solution is obtained by solving the explicit, transient and compressible lattice-Boltzmann equation implemented in the high-fidelity CFD/CAA solver Simulia PowerFLOW R®. The acoustic far-field is computed by using the Ffwocs-Williams & Hawkings integral solution applied to a permeable surface encompassing the fan-stage. Simulations are performed for an operating condition representative of a take-off with power cutback. Installation effects due to the BLI configuration are quantified by comparison with an isolated configuration of the modified Low-Noise SDT fan-stage geometry at same operating conditions. Comparisons are carried out in terms of fan-stage intake/interstage velocity fields, fan blades section air-loads and far-field noise; correlations between the fan-stage velocity field and noise emission for the BLI configuration are outlined. It is found that the BLI fan-stage is characterized by strong azimuthal fan blade loading unsteadiness, less periodic and coherent rotor wake tangential velocity variations and higher levels of in-plane velocity fluctuations compared to the isolated engine, resulting in far-field noise spectra with no distinct tonal components and higher broadband levels. This study represents the first high-fidelity CFD/CAA simulation of a full-scale aircraft geometry comprehensive of a BLI fan/Outlet Guide Vane (OGV) stage. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Wind Energ
Passive Q-switched mode locking of double-clading Yb : fiber laser with ion-implanted GaAs
No full textWe report the technique of the ion-implanted semi-insulating GaAs wafer used for passive Q-switched mode locking in double-cladding Yb:fiber laser. The wafer was implanted with 400-keV energy, 10(16)/cm(2) dose As+ ions, and was annealed at 600degreesC for 20 min. At the pump power of 5W, we achieved output power of 200mW. The repetition rate of envelope of Q-switched mode locking is 50-kHz with a FWHM envelope of 4mus. The repetition rate of mode locked pulse train was found to be 15-MHz. This is the first report of such a kind of laser to the best of our knowledge
- …
