925 resultados para evanescent-mode open-ended waveguide


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A novel sensing technique for the in situ monitoring of the rate of pulsed laser deposition (PLD) of metal thin films has been developed. This optical fibre based sensor works on the principle of the evanescent wave penetration of waveguide modes into the uncladded portion of a multimode fibre. The utility of this optical fibre sensor is demonstrated in the case of PLD of silver thin films obtained by a Q-switched Nd:YAG laser which is used to irradiate a silver target at the required conditions for the preparation of thin films. This paper describes the performance and characteristics of the sensor and shows how the device can be used as an effective tool for the monitoring of the deposition rate of silver thin films. The fibre optic sensor is very simple, inexpensive and highly sensitive compared with existing techniques for thin film deposition rate measurements

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A novel sensing technique for the in situ monitoring of the rate of pulsed laser deposition (PLD) of metal thin films has been developed. This optical fibre based sensor works on the principle of the evanescent wave penetration of waveguide modes into the uncladded portion of a multimode fibre. The utility of this optical fibre sensor is demonstrated in the case of PLD of silver thin films obtained by a Q-switched Nd:YAG laser which is used to irradiate a silver target at the required conditions for the preparation of thin films. This paper describes the performance and characteristics of the sensor and shows how the device can be used as an effective tool for the monitoring of the deposition rate of silver thin films. The fibre optic sensor is very simple, inexpensive and highly sensitive compared with existing techniques for thin film deposition rate measurements.

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With the recent progress and rapid increase in the field of communication, the designs of antennas for small mobile terminals with enhanced radiation characteristics are acquiring great importance. Compactness, efficiency, high data rate capacity etc. are the major criteria for the new generation antennas. The challenging task of the microwave scientists and engineers is to design a compact printed radiating structure having broadband behavior along with good efficiency and enhanced gain. Printed antenna technology has received popularity among antenna scientists after the introduction of planar transmission lines in mid-seventies. When we view the antenna through a transmission line concept, the mechanism behind any electromagnetic radiator is quite simple and interesting. Any electromagnetic system with a discontinuity is radiating electromagnetic energy. The size, shape and orientation of the discontinuities control the radiation characteristics of the system such as radiation pattern, gain, polarization etc. It can be either resonant or non-resonant. This thesis deals with antennas that are developed from a class of transmission lines known as coplanar strip-CPS, a planar analogy of parallel pair transmission line. The specialty of CPS is its symmetric structure compared to other transmission lines, which makes the antenna structures developed from CPS quite simple for design and fabrication. The structural modifications on either metallic strip of CPS results in different antennas. The first part of the thesis discusses a single band and dual band design derived from open ended slot lines which are very much suitable for 2.4 and 5.2 GHz WLAN applications. The second section of the study is vectored into the development of enhanced gain dipoles. A single band dipole and a wide band enhanced gain dipole suitable for 5.2/5.8 GHZ band and imaging applications are developed and discussed. Last part of the thesis discusses the development of directional UWBs. Three different types of ultra-compact UWBs are developed and almost all the frequency domain and time domain analysis of the structures are discussed.

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A compact coplanar waveguide (CPW)-fed uniplanar antenna with harmonic suppression characteristics is presented. The above characteristics are achieved by properly modifying the ground plane and adjusting the signal strip of an open-ended CPW-fed transmission line. The simulated and experimental characteristics of the antenna are presented, compared, and discussed.

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The data was collected to gauge Deakin University students' perceptions of the university's centralised learning management system, especially if it enhanced their learning experience. It identified the features that were most used and valued by the students and those they felt could be improved.

The dataset consists of a set of survey questions and the survey results in an electronic database. It comprises of 2908 responses from 2004 and 2526 responses from 2005; including approximately 1000 open-ended comments providing rich qualitative data.

The data includes the following categories of information:
• demographic and background information (including gender, mode of study);
• perception of importance of and satisfaction with a range of LMS functions;
• a number of overall LMS satisfaction measures; and
open-ended written comments about the LMS.

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The data was collected to guage Deakin University staff perceptions of the university's centralised learning management system, especially if it enhanced their teaching. It identified the features that were most used and valued by the teaching staff and those they felt could be improved.

The dataset is comprised of a set of survey questions and the survey results in an electronic database. It consists of 156 responses from 2004 and 120 responses from 2005; including approximately 100 open-ended comments providing rich qualitative data.

The data includes the following categories of information:
• demographic and background information (including gender, mode of study);
• perception of importance of and satisfaction with a range of LMS functions;
• a number of overall LMS satisfaction measures; and
open-ended written comments about the LMS.

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The temporal pattern of bone-level alterations in conventionally restored implants is dependent upon healing mode (open or submerged). This study examined the influence of healing on marginal bone levels at implants with a medium-rough surface including the implant collar and a clearance-fit implant-abutment connection restored according to a platform-switching concept.

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Moisture induced distresses have been the prevalent distress type affecting the deterioration of both asphalt and concrete pavement sections. While various surface techniques have been employed over the years to minimize the ingress of moisture into the pavement structural sections, subsurface drainage components like open-graded base courses remain the best alternative in minimizing the time the pavement structural sections are exposed to saturated conditions. This research therefore focuses on assessing the performance and cost-effectiveness of pavement sections containing both treated and untreated open-graded aggregate base materials. Three common roadway aggregates comprising of two virgin aggregates and one recycled aggregate were investigated using four open-ended gradations and two binder types. Laboratory tests were conducted to determine the hydraulic, mechanical and durability characteristics of treated and untreated open-graded mixes made from these three aggregate types. Results of the experimental program show that for the same gradation and mix design types, limestone samples have the greatest drainage capacity, stability to traffic loads and resistance to degradation from environmental conditions like freeze-thaw. However, depending on the gradation and mix design used, all three aggregate types namely limestone, natural gravel and recycled concrete can meet the minimum coefficient of hydraulic conductivity required for good drainage in most pavements. Tests results for both asphalt and cement treated open-graded samples indicate that a percent air void content within the range of 15-25 will produce a treated open-graded base course with sufficient drainage capacity and also long term stability under both traffic and environmental loads. Using the new Mechanistic and Empirical Design Guide software, computer simulations of pavement performance were conducted on pavement sections containing these open-graded base aggregate base materials to determine how the MEPDG predicted pavement performance is sensitive to drainage. Using three truck traffic levels and four climatic regions, results of the computer simulations indicate that the predicted performance was not sensitive to the drainage characteristics of the open-graded base course. Based on the result of the MEPDG predicted pavement performance, the cost-effectiveness of the pavement sections with open-graded base was computed on the assumption that the increase service life experienced by these sections was attributed to the positive effects of subsurface drainage. The two cost analyses used gave two contrasting results with the one indicating that the inclusion of open-graded base courses can lead to substantial savings.

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John Frazer's architectural work is inspired by living and generative processes. Both evolutionary and revolutionary, it explores informatin ecologies and the dynamics of the spaces between objects. Fuelled by an interest in the cybernetic work of Gordon Pask and Norbert Wiener, and the possibilities of the computer and the "new science" it has facilitated, Frazer and his team of collaborators have conducted a series of experiments that utilize genetic algorithms, cellular automata, emergent behaviour, complexity and feedback loops to create a truly dynamic architecture. Frazer studied at the Architectural Association (AA) in London from 1963 to 1969, and later became unit master of Diploma Unit 11 there. He was subsequently Director of Computer-Aided Design at the University of Ulter - a post he held while writing An Evolutionary Architecture in 1995 - and a lecturer at the University of Cambridge. In 1983 he co-founded Autographics Software Ltd, which pioneered microprocessor graphics. Frazer was awarded a person chair at the University of Ulster in 1984. In Frazer's hands, architecture becomes machine-readable, formally open-ended and responsive. His work as computer consultant to Cedric Price's Generator Project of 1976 (see P84)led to the development of a series of tools and processes; these have resulted in projects such as the Calbuild Kit (1985) and the Universal Constructor (1990). These subsequent computer-orientated architectural machines are makers of architectural form beyond the full control of the architect-programmer. Frazer makes much reference to the multi-celled relationships found in nature, and their ongoing morphosis in response to continually changing contextual criteria. He defines the elements that describe his evolutionary architectural model thus: "A genetic code script, rules for the development of the code, mapping of the code to a virtual model, the nature of the environment for the development of the model and, most importantly, the criteria for selection. In setting out these parameters for designing evolutionary architectures, Frazer goes beyond the usual notions of architectural beauty and aesthetics. Nevertheless his work is not without an aesthetic: some pieces are a frenzy of mad wire, while others have a modularity that is reminiscent of biological form. Algorithms form the basis of Frazer's designs. These algorithms determine a variety of formal results dependent on the nature of the information they are given. His work, therefore, is always dynamic, always evolving and always different. Designing with algorithms is also critical to other architects featured in this book, such as Marcos Novak (see p150). Frazer has made an unparalleled contribution to defining architectural possibilities for the twenty-first century, and remains an inspiration to architects seeking to create responsive environments. Architects were initially slow to pick up on the opportunities that the computer provides. These opportunities are both representational and spatial: computers can help architects draw buildings and, more importantly, they can help architects create varied spaces, both virtual and actual. Frazer's work was groundbreaking in this respect, and well before its time.

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This thesis reports the outcomes of an investigation into students’ experience of Problem-based learning (PBL) in virtual space. PBL is increasingly being used in many fields including engineering education. At the same time many engineering education providers are turning to online distance education. Unfortunately there is a dearth of research into what constitutes an effective learning experience for adult learners who undertake PBL instruction through online distance education. Research was therefore focussed on discovering the qualitatively different ways that students experience PBL in virtual space. Data was collected in an electronic environment from a course, which adopted the PBL strategy and was delivered entirely in virtual space. Students in this course were asked to respond to open-ended questions designed to elicit their learning experience in the course. Data was analysed using the phenomenographical approach. This interpretative research method concentrated on mapping the qualitative differences in students’ interpretations of their experience in the course. Five qualitatively different ways of experiencing were discovered: Conception 1: ‘A necessary evil for program progression’; Conception 2: ‘Developing skills to understand, evaluate, and solve technical Engineering and Surveying problems’; Conception 3: ‘Developing skills to work effectively in teams in virtual space’; Conception 4: ‘A unique approach to learning how to learn’; Conception 5: ‘Enhancing personal growth’. Each conception reveals variation in how students attend to learning by PBL in virtual space. Results indicate that the design of students’ online learning experience was responsible for making students aware of deeper ways of experiencing PBL in virtual space. Results also suggest that the quality and quantity of interaction with the team facilitator may have a significant impact on the student experience in virtual PBL courses. The outcomes imply pedagogical strategies can be devised for shifting students’ focus as they engage in the virtual PBL experience to effectively manage the student learning experience and thereby ensure that they gain maximum benefit. The results from this research hold important ramifications for graduates with respect to their ease of transition into professional work as well as their later professional competence in terms of problem solving, ability to transfer basic knowledge to real-life engineering scenarios, ability to adapt to changes and apply knowledge in unusual situations, ability to think critically and creatively, and a commitment to continuous life-long learning and self-improvement.

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This review article uses the work of Italian scholar Milly Buonanno to review the state and future of television scholarship, given that the ‘age of television’ has been overtaken by the age of computer-based media. In particular, it discusses the role of open-ended narrative through which we collectively explore the human condition.

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The standard of English as a Foreign Language (EFL) education has prompted calls for reform to preservice EFL teacher education. Field experiences are central to their professional development and for implementing reform measures. This study aims to examine preservice EFL teachers’ attitudes, needs, and experiences about learning to teach writing in English before their practicum in Vietnamese high schools. An open-ended questionnaire collected data from 97 preservice EFL teachers at the beginning of their final practicum. The data suggested that these preservice EFL teachers were motivated to learn to teach English in general and teaching writing in particular but required mentors to model effective teaching practices and share their teaching experiences. They also needed their mentors to be enthusiastic and supportive, and provide constructive feedback. These findings may assist teacher educators and school mentors for motivating and developing preservice EFL teachers’ practices.

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The middle schooling movement in Australia has gained momentum in the past 10 to 15 years (Pendergast & Bahr, 2005) with much of the literature recognising that preservice teachers need to graduate with theoretical and pedagogical knowledge to engage middle years students (Education Queensland, 2004). This qualitative study analysed the responses of preservice teachers towards their completion of a four-year Bachelor of Education primary degree that included a middle years pathway (or electives). The study aims to investigate the final years’ perceptions of their confidence and preparedness to teach in the middle-school context as a result of their university learning. Data were gathered using open-ended one-to-one interviews of approximately 45 minutes duration. Seven of the twenty-two final-year preservice teachers were involved in the study that represented 32% of the cohort. Results indicated the need for increased school-based units, the importance of pedagogical approaches employed by the lecturer and the preference for further linkages between middle school theories and middle school teaching practices. Those who provide teacher education courses need to consider the importance of how they deliver middle years courses as well as the content of the course. Furthermore, teacher education institutions need to evaluate and re-shape their courses to ensure preservice teachers are provided with real-world experiences related to both the literature and the profession.

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Previous research into the use of explicit and implicit conclusions in advertising has yet to demonstrate consistent effects for both brand attitudes and purchase intentions. While research has examined the role of involvement, this study contributes by examining the trait called need for cognition (NFC), which addresses a person’s propensity to engage in effortful thinking. In addition, this study introduces argument quality (AQ) as another potential moderator of conclusion explicitness effects. In a 2 × 2 experiment of 261 subjects, conclusion explicitness (explicit conclusion, implicit conclusion) and AQ (strong, weak) are manipulated, with NFC (high NFC, low NFC) as a third measured variable. Results indicate more favorable evaluations for implicit conclusions over explicit conclusions for high-NFC individuals. Further, implicit conclusions result in more favorable brand attitudes and purchase intentions when linked with strong AQ for high-NFC individuals. The findings confirm that conclusion explicitness does not differentially affect the evaluations of low-NFC subjects. Results suggest that NFC may represent an important moderating variable for future conclusion explicitness research.

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This book reports the outcomes of an investigation into discovering the qualitatively different ways that students experience Problem-based learning (PBL)in virtual space. PBL is increasingly being used in many fields including engineering education. At the same time, many engineering education providers are turning to online distance education. Unfortunately there is a dearth of research into what constitutes an effective learning experience for adult learners who undertake PBL instruction through online distance education. Data were collected from a course which adopted the PBL strategy and was delivered entirely in virtual space. Students were asked to respond to open-ended questions designed to elicit their learning experiences. Data were analysed using the phenomenographic approach. Five qualitatively different ways of experiencing PBL in virtual space were discovered. Results indicate that the design of students' online learning experience was responsible for making students aware of deeper ways of experienceing PBL in virtual space. The outcomes imply that pedagogical strategies can be devised for shifting students' focus as they engage in virtual PBL.