| 1. |
- Abbes, Yacine
(författare)
-
Educational studies in heat and power technology : how students learn with multimedia tools and problem-based learning
- 2005
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Higher education is undergoing continuous changes and new learning tools and methods are implemented. Researchers in education do not always agree upon the effectiveness of some of the methods introduced into engineering education. The present thesis consists of two case studies on educational methods introduced at the Department of Energy Technology, at Royal Institute of Technology (KTH), Sweden. The qualitative research methodology has been used in case one and a combination of qualitative and quantitative methodology has been used in the second case. The sources of evidences consisted of: unstructured interviews, analysis of video recording, questionnaires, and analysis of a variety of documents. In the first case, an educational program in heat and power technology was analysed. The second case consists in an in-depth study of group dynamics in a Problem –Based Learning course. These studies showed that the learning approach adopted by students depends strongly on the way they view the particular learning tool or method. The first case study revealed the existence of two types of learners. Surfacelearners follow the structure suggested by the designers of the multimedia program. This category of learners focuses only on the material available in the program. Deep-learners go beyond the information and the structure suggested in the program and combine different learning tools in their learning. These students do not follow the structure of the tutorials’ of the multimedia program. This study showed that students who had a strong view how to learn with a multimedia program or a learning method benefited less from the learning tools available. Students with weak views on how to learn from educational program or leaning tool benefit less from the presentation and engage in more surface learning. Self-motivated learners use the multimedia presentation in novel ways and crosscheck the information given with other material. The second study showed that students have unclear and weak views on how to learn with student-directed Problem- Based Learning model. Four types of learners were identified in Problem-Based Learning project: Leaders, Key Actors, Common Students and Social Loafers. Leaders and Key Actors are self-motivated individuals and participate most in the projects. Students who viewed themselves or were viewed as leaders were held responsible to take most of the decisions and students expected them to work more than the average student. Students who viewed themselves as common team members expected a lower workload than leaders’. Key Actors are self-motivated students who do not view themselves as separate from other group members but who participate more than others. Leaders learned more group and social processes, that they did not fully take part in, while common students learned more from the project management aspects that they did not take part in. The study also found that Problem-Based Learning groups can become very cohesive, and can develop distorted views on how to learn with Problem-Based Learning, and un-common group dynamics phenomena such as groupthink can occur in Problem-Based Learning setting.
|
|
| 2. |
- Erlich, Catharina, et al.
(författare)
-
Thermochemical characteristics of sugar cane bagasse pellets
- 2005
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 84:5, s. 569-575
-
Tidskriftsartikel (refereegranskat)abstract
- Pelletisation facilitates utilisation of sugar cane bagasse as a fuel and storage for year-round electricity generation. The present work determines thermochemical characteristics of bagasse pellets of different sizes and origins, using various temperatures (600, 750 and 900 degrees C) and gas flow rates (4, 7 and 10 L/min) with varying concentrations of oxygen (5, 10 and 15 %) in mixtures with nitrogen. Of major interest are the effects of raw material, origin and size of pellets, and the treatment conditions on the rate of pyrolysis and the structure and reactivity of char in combustion. The char yield of the larger pellets of high-ash content bagasse was practically independent of treatment conditions. Smaller pellets gave better mechanical stability of the char but lower reactivity.
|
|
| 3. |
- Fedulov, Vitali
(författare)
-
Educational evaluation of an interactive multimedia learning platform : computerized educational platform in heat and power technology
- 2005
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Learning materials have multiple forms, such as books, overhead slides, computer files, blackboard notes by teachers, narration to the notes, video/audio tapes etc. Since the forms are highly inhomogeneous, it becomes difficult to collect and practically use them by a particular learner for individual study at home. Such multiple media are also expensive in management, since human resources are needed to keep the material repositories in order. One solution of the problem lies in centralized active digital repositories. Such repositories aim to simplify the learner’s work and boost learning efficiency. With introduction of interactivity and live communication tools such repositories become learning platforms exceeding the functionality of “passive” digital libraries. Such learning platforms could be easily used both for on-campus and distance education. This dissertation presents an evaluation of a digital repository of interactive multimedia content in the field of Heat and Power Technology: Computerized Educational Platform (CompEdu HPT). The platform evaluation consisted of integration of the tool into the university curriculum and then collection of feedback from students and teachers. The evaluation concerned usefulness of the platform for learning, aspects of instruction improvement, collecting observations about how the platform is used by students, as well as their opinions about the IT application direction chosen. The methods included: online feedback forms, questionnaires, interviews, discussions and observations. The evaluation demonstrated that the main strength of the platform is the integration of learning materials in one portable package. The students appreciated structured and logically arranged information that was available for easy access. Coverage of a broad area of knowledge related to heat and power technology was also pointed out as an advantage with reflection on the very low price of acquisition of the materials. The most popular elements of the content in use included: simulations, lecture notes, the print function, the glossary, and calculation exercises. A major part of the students declared the high value of CompEdu in facilitating home study. Nevertheless, not all the students had a positive impression: around one-fifth of them did not find the platform useful and expressed preference for more traditional learning media. The majority of the negative opinions concerned content quality, which directly related to weaknesses of the content production and review process. The evaluation emphasized the importance of material quality and amount as the key issue for a good learning platform with relatively smaller importance of presentation forms. The evaluation also considered aspects of functionality from the user point of view. Differentiation between popularity of simulations showed that simulations used by teachers during lectures have higher educational value than those for individual use only. The popularity of the printing option indicated a need for adaptation of digital materials for paper publishing. The general conclusion for practical use of multimedia tools in education was that high usability and simplicity of information access should be the focus point of any chosen approach in the direction. The CompEdu evaluation suggested that after thorough content review and addition of an efficient search mechanism the platform can successfully deliver rich learning content. The platform gave an extensive real-case illustration of how multimedia can be used in educational practice. Due to the evaluation, the CompEdu e-learning group has collected rich experience and know-how in the field of active knowledge repositories. The experience will be used for development of a more sophisticated learning platform working in the global Internet environment with major focus on information accessibility by easy search.
|
|
| 4. |
- Fransson, Christer, 1956, et al.
(författare)
-
Prevalence of subjects with progressive bone loss at implants.
- 2005
-
Ingår i: Clinical oral implants research. - : Wiley. - 0905-7161. ; 16:4, s. 440-6
-
Tidskriftsartikel (refereegranskat)abstract
- AIM: The aim of the present study was to assess the prevalence of subjects with progressive bone loss at implants with a function time of at least 5 years. MATERIAL AND METHODS: Radiographs of 1346 patients who had attended annual follow-up visits at the Brånemark Clinic, Public Dental Services, Gothenburg, Sweden were retrieved. Six hundred and sixty-two subjects fulfilled the inclusion criteria. Thus, they all had been provided with implant-supported (Brånemark System) Nobel BioCare, Gothenburg, Sweden) fixed partial or complete dentures or single-tooth replacements with a documented function time in radiographs of at least 5 years. Implants that demonstrated progressive bone loss to a level of > or =3 threads of an implant were detected. The number of subjects who exhibited one or more implants with progressive bone loss to the threshold level was recorded. RESULTS: Twenty-eight percent of 662 included subjects had one or more implants with progressive bone loss. A logistic regression analysis revealed that the individuals in this group carried a significantly larger number of implants than the subjects in whom no implants with progressive loss were detected (6 vs. 4.8). Furthermore, >30% of the subjects in the group with progressive bone loss had > or =3 identified implants and that about 33% of all such implants in this group exhibited extensive bone loss. Out of the total 3413 implants included in the study, 423 implants (12.4%) demonstrated progressive bone loss. CONCLUSION: It is suggested that the prevalence of progressive bone loss at implants assessed from subject-based data is higher than that evaluated from implant-based data.
|
|
| 5. |
|
|
| 6. |
- Kessar, Alexandros, et al.
(författare)
-
Flow Measurements for Low Engine order Excitations in a High Pressure Turbine stage
- 2005
-
Konferensbidrag (refereegranskat)abstract
- This paper demonstrates and evaluates unique flow measurement results obtained in a high pressure test turbine, in order to analyze the effect of Low Engine Order (LEO) excitations. A stator was modified to induce LEO flow variations by either imposing a throat width variation or a blockage of the trailing edge cooling flow from some of the vanes. Laser Two Focus (L2F) and pressure probe measurements were performed at subsonic and transonic flow conditions, without and with the rotor installed and operated. Time resolved velocity data was obtained in front and inside of rotor passages covering the Low Engine Order variation period. The presented results evaluation focuses only on L2F measurements and show that the LEO variation of flow velocity and turbulence intensity is most visible in the gap between stator and rotor and at the first measurement location inside the rotor passage. The overall trend is that stator exit flow Mach numbers are higher behind the passages with smaller pitch and vice versa.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Mårtensson, H., et al.
(författare)
-
Assessment of a 3D Linear Flutter Prediction Tool using Sector Cascade Test Data
- 2005
-
Ingår i: Proceedings of the ASME Turbo Expo 2005, Vol 4. - : ASME Press. - 0791847276 ; , s. 613-623
-
Konferensbidrag (refereegranskat)abstract
- An assessment and validation of a numerical prediction tool for flutter are made using new experimental data from experiments on turbine blades in a sector cascade. The 3D geometry is that of a low-pressure (LP) turbine blade with twist and a profile that changes along span in an annular sector cascade. The numerical model is a linear harmonic Euler equation solver. Rig results are obtained for the blade by oscillating I blade out of 7 in the annular sector cascade. The blade is oscillated in the rig using a mechanical type of actuator to control the mode. The mode shapes in the rig consist of torsion and bending modes around a pivot mechanism fixed inside the hub end wall. The frequencies obtained in the rig are in the range up to 219 Hz, or reduced frequency based on full chord k=0.5, which covers the range of useful reduced frequencies typically found in turbine designs. Under reference running conditions the unsteady pressure responses are found qualitatively in line with the experiment. The test case is shown to be challenging to the numerical tool in terms of effects of tip clearance as well as off-design effects. In order to improve results tip clearance modeling and inclusion of viscous terms are identified as key factors.
|
|
| 10. |
- Persson, Katarina, et al.
(författare)
-
Supported palladium-platinum catalyst for methane combustion at high pressure
- 2005
-
Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 100, s. 479-483
-
Tidskriftsartikel (refereegranskat)abstract
- Catalytic combustion of methane over a supported bimetallic Pd-Pt catalyst and a monometallic Pd catalyst has been investigated experimentally. Two different reactor configurations were used in the study, i.e. a tubular lab-scale reactor working at atmospheric pressure and a high-pressure reactor working at up to 15 bar. The results showed that the bimetallic catalyst has a clearly more stable activity during steady-state operation compare to the palladium only catalyst. The activity of the bimetallic catalyst was slightly higher than for the palladium catalyst. These results were established in both test facilities. Further, the impact of pressure on the combustion activity has been studied experimentally. The tests showed that the methane conversion decreases with increasing pressure. However, the impact of pressure is more prominent at lower pressures and levels out for pressures above 10 bar
|
|
