147,793 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
New Sufficient Conditions for the g-maximumInequality
No full textIn this paper, we give new sufficient conditions for the existence of a solution of theg-maximum equality. As an application, we prove a new fixed point theorem.Ky Fan inequality, g-maximum equality, fixed point.
On the Ky Fan Inequality
No full textSome inequalities related to the Ky Fan and C.-L. Wang inequalities for weighted arithmetic and geometric means are given
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
Ky Fan Inequality and Bounds for Differences of Means
No full textWe prove an equivalent relation between Ky Fan-typed inequalities and certain bounds for the differences of means. We also generalize a result of H. Alzer, S. Ruscheweyh and L. Salinas
On Some Analogues of Ky Fan-type Inequalities
No full textWe study the behavior of means under equal increments of their variables and we apply the results to Ky Fan-type inequalities and certain bounds for the differences of means. We also give a sharpening of Sierpiński’s inequality and prove a Rado-type inequality
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
Design of a low speed vaneaxial fan
No full textThe ventilation of industrial areas and tunnels is a safety requirement and
characterizes the quality of a working environment. Low speed fans are used to
achieve the required ventilation level. An attempt to design a low speed
vaneaxial fan, meeting the specifications of a given fan that is already in the
market takes place in this Thesis. The project was conducted with the support of
the Fläkt-Woods Company and the main target is to design a ventilation fan,
meeting the requirements for pressure rise, volume flow and size, of an existing
model. The efficiency improvement is driven in part by the new national and
international legislation concerning the operation of electrical equipment.
Companies require higher efficiencies without compromising safety features of
the fan and the fan capability to operate at high temperatures.
A low speed fan design procedure is established based on the available
literature and design tools. The free vortex approach is employed, which provides
acceptable efficiency and relatively simpler design. The design procedure can be
used to design a fan given a set of customer requirements. Many software tools
are used to design the fan. A Matlab code for the blade design is developed and
other codes are used to establish the final fan design. The effectiveness of the
design procedure is verified with CFD simulations carried out as part of this
project. Three new designs that are developed with the established design
procedure are presented in this Thesis. The new designs differ in the hub to tip
ratio, the rotational speed and the number of the blades and the vanes. The
experience acquired from the analysis of the performance of the first new design
is used to improve the performance of the following designs in order to achieve
the best efficiency possible. The effect of tip clearance is investigated thoroughly
in the new designs because the tip clearance has a major impact on the fan
performance and safe operation of the fan at high temperatures. The mechanical
integrity of the fan is examined last to verify that the fan can operate in high
temperature.
The target of improved efficiency (higher than 79%) is achieved in one of
the fan designs attempted and it was calculated 82%. The off design
performance of the new fan is satisfactory as well. This new design can be
further optimized, since the modification of minor design features is in itself a
methodology that can incrementally improve the efficiency of a low speed fan.
The new fan can operate at high temperatures (400°C), however the safety factor
at this temperature is 1.25 for combined steady mechanical and thermal loading
and it can be further improved either through the use of materials with better
resistance in thermal loading or with an increased tip clearance
On a Class of Ky Fan-Type Inequalities
No full textIn this paper, we study one class of Ky Fan-type inequalities, which has ties with the
original Ky Fan inequality. Our result extends the known ones
A New Approach to Ky Fan-type Inequalities
No full textThe study of the behavior of means under equal increments of their variables provides a new approach to Ky Fan-type inequalities. Via this new approach we are able to prove some new results on Ky Fan-type inequalities
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