2,137 research outputs found
A Note on the Ky Fan Inequality
No full textThe Ky Fan inequality is essentially the assertion that t/(1−t) is log-concave. We study its weighted form in the context of signed weights
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
Learning of algorithms: a theoretical model with focus on cognitive development
No full textTaking a broad perspective on algorithm in mathematics, the author presents a theoretical model about the learning and teaching of algorithm with focus on students’ cognitive development. The model consists of three cognitive levels: 1. Knowledge and Skills, 2. Understanding and Comprehension, and 3. Evaluation and Construction. The model suggests that teaching and learning of algorithm does not simply mean routine learning, memorization, or lead to a low level of cognition. The paper also discusses different teaching strategies and activities that can be used to support students’ cognitive development at different cognitive levels
Análisis y caracterización temporo-espacial de la morfología Fan-Delta en la localidad de Huinay, Fiordo Comau, región de Los Lagos
No full textMemoria para optar al título de GeógrafoA partir del análisis geomorfológico se estudia la morfología fan-delta asociada a la desembocadura
de los ríos Huinay y Lloncochaigua, en la localidad de Huinay, fiordo Comau, región de Los Lagos.
Se analizó el contexto especifico territorial y geográfico del ambiente periglacial inserto en cuencas
norpatagonicas, con el propósito de caracterizar la morfología deltaica a través de imágenes y
fotografías aéreas de las últimas tres decadas desde 1982, analizando la morfología y los cambios
internos en las formas deltaicas de Huinay-Lloncochaigua. Se realizó cartografías geomorfológicas
bajo las diferentes condiciones de marea, identificando la dinámica subaérea y subacuática de las
formas estudiadas. El trabajo de terreno realizado en enero y junio 2016, permitió definir la naturaleza
del fan-delta, debido a la marcada impronta aluvial de los lóbulos deltaicos, el patrón braided
característico de flujos con abundante carga sedimentaria y bancos compuestos por gravas de origen
fluvial. Los resultados obtenidos revelan los patrones de cambio y tendencia evolutiva de la
morfología asociada al litoral cercano, los cuales indican que el fan-delta Huinay actualmente se
encuentra en procesos de acumulación, acreción y progradación de material. Se plantea la necesidad
de avanzar en la investigación de estas formas, más aún en escenarios de cambio ambiental asociados
a la disminución de las precipitaciones y aumento de las temperaturas durante el presente siglo
Aerodynamic design and evaluation of a ducted fan lift system for vertical takeoff and landing flying cars
No full textUrban air mobility is a relatively new concept that has been proposed in recent years as a means of transporting passengers and goods in urban areas. It encompasses a diverse range of Vertical TakeOff and Landing (VTOL) vehicles that function more like passenger-carrying drones for on-demand transportation. Among them, the car-like VTOL is advantageous due to its compact configuration, safe rotors, high user affinity, and technological fashion. These characteristics are frequently derived from the flying car’s Ducted Fan Lift System (DFLS). This study aims to develop a method for the rapid design and the evaluation of the aerodynamic performance of the DFLS, to support the preliminary scheme demonstration of the ducted fan flying car. The proposed method uses blade element theory to design the unducted fan and applies momentum theory to calculate the aerodynamic thrust of the DFLS. The DFLS of a 1:3 scale verifier for a flying car scheme was designed and evaluated using the proposed method and a numerical method, respectively. To validate the proposed method, a prototype of the scale DFLS was manufactured and tested, and the result was compared with those of the proposed theoretical method and the numerical method. This study demonstrates that while both the theoretical and numerical methods are capable of designing an unducted fan accurately, the theoretical method is simpler and faster. Compared to the DFLS test results, the theoretical method’s average difference is approximately 1.9%. When evaluating the DFLS, the accuracy of the numerical calculation is reduced, and the difference is greater than 30% at low power. The theoretical method presented in this paper can be used to improve the aerodynamic design and evaluation efficiency of the DFLS and to aid in the configuration evaluation of VTOLs equipped with ducted fans.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.Control & Simulatio
Spectrums of investment in Doctor Who fandom
No full textThis thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Drawing upon a significant weight of empirical data, collected in the field, this thesis proposes a set of four spectrums of investment engaged in by cult media fans: the spectrum of financial investment; the spectrum of what is here termed 'participatory investment'; the spectrum of investment in the idea of textual authenticity; and the spectrum of multiple investments. The spectrum model allows the individual members of the research sample to be located within specific regions of each spectrum and correlations to be drawn between the distinct spectrums, in order for any patterns which emerge to be examined. The thesis also reviews a number of relevant theoretical concerns such as fan studies, ethnography and social psychology
Soft power: Power of attraction or confusion?
No full textDespite its popularity soft power remains power of confusion. The paper examines the concept, with a special focus on the nature and sources of soft power. Nye’s notion of soft power is largely ethnocentric and based on the assumption that there is a link between attractiveness and the ability to influence others in international relations. This poses two problems: Firstly, a country has many different actors. Some of them like the attraction and others don’t. Whether the attraction will lead to the ability to influence the policy of the target country depends on which groups in that country find it attractive and how much control they have on policymaking. Secondly, policymaking at the state level is far more complicated than at the personal level; and has different dynamics that emphasise the rational considerations. This leaves little room for emotional elements thus significantly reducing the effect of soft power. Given the nature of soft power being uncontrollable and unpredictable, it would be impossible to wield soft power in any organised and coordinated fashion as Nye suggested. Furthermore, the relationship between two countries is shaped by many complex factors. It is ultimately decided by the geopolitics and strategic interests of nations, in which soft power may play only a limited role. The paper also discusses the link between soft power and nation branding as both concepts are concerned with a nation’s influence on the world stage. Public diplomacy is a subset of nation branding that focuses on the political brand of a nation; whereas nation branding is about how a nation as whole to reshape the international opinions. A successful nation branding campaign will help create a more favourable and lasting image among the international audience thus further enhancing a country’s soft power
Consumption outside the market: an ethnography of consumer resistance among football fans
No full textThis study analysed football fandom utilising an ethnographic approach. Football fandom was selected as a research site for the study because it offered scope to explore for the presence of non-traditional forms of cultural capital (Bourdieu 1984).
It also offered scope to explore the extent to which fandom was a form of sacred consumption (Belk et a1 1989). Ethnography was selected as an appropriate methodology for several reasons. It provided the opportunity to develop a holistic perspective on fandom and it further provided scope to utilise an emergent design approach in the development of a conceptual understanding of fandom. What emerged fiom the ethnographic investigation of two separate football fan communities was that consumers experience and maintain a sense of the sacred by operating their own unofficial markets in competition with the official market in fanrelated goods and services. They also maintain localised systems of cultural capital which allow them to socially construct and maintain a sense of hierophany within their own communities (Belk et a1 1989), in opposition to the homogenised fan identity proffered by the official market. These systems of cultural capital not only allow fans to experience the sacred but also facilitate their sense of relationship with like-minded others in self-selecting communities of shared taste
Design of a crushing and agglomeration process for manufacturing bagasse charcoal
No full textThesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 33-34).In Haiti, wood and wood charcoal are common fuels for cooking. This practice has contributed to deforestation, leading to erosion and fatal floods. The availability of charcoal made from a different source other than wood, such as agricultural waste, might provide Haitians with an alternative, more sustainable fuel, which in turn may reduce fuel prices. MIT students have developed various methods for producing charcoal out of simple inexpensive devices. In a current manufacturing process, carbonized bagasse is crushed to a powder, then mixed and agglomerated with yucca binder into balls. A novel method may reduce operator exposure and inhalation of charcoal fines by keeping primary manufacturing phases in the oil drum and reducing the operational steps of transferring the material from one location to another. The goal of this thesis was to understand, test, and optimize the parameters of this novel crushing and agglomeration process. The final prototype was found to effectively crushing charcoal and mix charcoal with binder to some extent, while being an inexpensive alternative to reduce overall charcoal exposure. However, the mixing and agglomeration was not sufficiently uniform and further designs should be considered to increase uniformity of mixing of binder and charcoal.by Victoria Y. Fan.S.B
A Computational Study on the Aerodynamics of a 90 mm Ducted Contra-Rotating Lift Fan
No full textIn this paper, a steady 3D numerical study has been conducted on a 90 mm counter rotating lift fan to investigate its aerodynamic performance. The effect of axial distance between the fans and rotor speed are studied. A low thrust generation has been revealed from the simulation results due to the unfavourable working condition for the upstream rotor. Subsequently, an inlet guide vane (IGV) is geometrically designed to cause a preswirl effect at the inlet. Results show that the pressure ratio and total thrust are significantly improved at 10% by the IGV with a little sacrificing in efficiency. Such work can be a guidance in the further design and optimization
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