Fakultet for naturvitenskap og teknologi
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Fakultet for naturvitenskap og teknologi
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- EISCAT [14]
- Institutt for fysikk og teknologi [120]
- Institutt for geologi [45]
- Institutt for informatikk [105]
- Institutt for ingeniørvitenskap og sikkerhet [1]
- Institutt for kjemi [26]
- Institutt for matematikk og statistikk [63]
- Tromsø geofysiske observatorium [15]
Collections in this community
Recent additions
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Paulsen, Britt (Master thesis; Mastergradsoppgave, 15-Nov-2011)[+][-]
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Andberg, Tor Arne Heim (Master thesis; Mastergradsoppgave, 15-Nov-2011)[+][-]
Abstract: Absolute binding free energies for the third domain of the turkey ovomucoid inhibitor in complex with Streptomyces griseus proteinase B and porcine pancreatic elastase has been calculated using the linear interaction energy method. URI: http://hdl.handle.net/10037/3820 File(s) in this item: 1
thesis.pdf (2.515Mb) -
Klemetsen, Øystein (Doctoral thesis; Doktorgradsavhandling, 01-Feb-2012)[+][-]
Abstract: The topic covered in this thesis is medical temperature measurement of subcutaneous parts of human tissue with use of microwave radiometry. Radiometry is a completely non-invasive, non-toxic and relatively inexpensive sensing modality. The radiometric technique is based on the measurement of electromagnetic noise power emitted by lossy materials. The method has explicit low investment costs and low technological complexity, but relatively low spatial resolution. Still the method can be useful for some dedicated medical applications. Fundamental radiometric theory and dielectrical properties of biological tissues are derived. The process to realize a miniaturized radiometer is going from active antenna configuration to a complete miniaturized radiometer and finally to a modular radiometer, that is used \textsl{in-vivo} on humans. Different radiometers were designed, simulated, built and tested on realistic human phantoms. \textit{In vivo} experiments were also conducted to verify the prototype radiometer and to test the ability to be used in tailored medical diagnostics. The primary application covered is temperature gradient measurement during microwave hyperthermia and in pediatric vesicouretaral reflux (VUR) detection. Hyperthermia is a therapeutic technique in which cancerous tissue is heated to 40-45$^\circ$C, inducing vascular and cellular changes that improve the therapeutic effectiveness when used in conjunction with chemotherapy or radiation therapy. VUR is abnormal flow of urine from the bladder back to the upper urinary tract. Another application where this radiometer can be of great interest is in breast cancer diagnostic. Breast cancer is a type of cancer that forms in tissues of the breast; usually in the ducts and lobules and can occur in both men and woman. We present results from radiometric measurement on human phantoms during a hyperthermia heating sequence. Experimental evidence shows that radiometry can be used for temperature quality assurance of the heated volume in depth. In VUR detection, the first step is to heat the bladder prior to detection of the reflux. We present results from measurements \textsl{in-vivo} with a water filled balloon in the human mouth, that mimics pediatric bladder heating. Results show that the radiometer can be used as the first step in the novel VUR detection. Radiometry antennas are one of the most critical components in a radiometer system. An elliptical printed circuit board antenna is designed and matched to the human body. Further, an antenna with suction, with use of negative pressure to mount the antenna onto the human body for improved radiometric performance, was also proposed and built. The simple and elegant solution for the coupling of the antenna with use of negative pressure, documents improved performance in estimating the true temperature as well as exhibiting smaller fluctuation in the radiometric signal. Description: The papers of this thesis are not available in Munin:
1. Ø. Klemetsen, Y. Birkelund, and S. K. Jacobsen: 'Design of medical radiometer front-end for improved performance', Progress In Electromagnetics Research B (2011) Vol. 27, 289–306. Available at http://www.jpier.org/PIERB/pier.php?paper=10101204
2. Øystein Klemetsen, Svein Jacobsen and Yngve Birkelund: 'Radiometric temperature reading of a hot ellipsoidal object inside the oral cavity by a shielded microwave antenna put flush to the cheek' (paper in review)
3. Øystein Klemetsen and Svein Jacobsen: 'Improved Radiometric Performance Attained by an Elliptical Microwave Antenna With Suction', IEEE transactions on biomedical engineering (2012)59(1):263-271. Available at http://dx.doi.org/10.1109/TBME.2011.2172441
4. Yngve Birkelund, Øystein Klemetsen, Svein K. Jacobsen, Kavitha Arunachalam, Paolo Maccarini, and Paul R. Stauffer: 'Vesicoureteral Reflux in children : a phantom study of microwave heating and radiometric thermometry of pediatric bladder', IEEE transactions on biomedical engineering (2011)58(11):3269-3278. Available at http://dx.doi.org/10.1109/TBME.2011.2167148
5. Svein Jacobsen and Øystein Klemetsen: 'Improved detectability in medical microwave radio-thermometers as obtained by active antennas', IEEE transactions on biomedical engineering (2008)55(12):2778-2785. Available at http://dx.doi.org/10.1109/TBME.2008.2002156URI: http://hdl.handle.net/10037/3818 File(s) in this item: 1
thesis.pdf (6.930Mb) -
Viken Valvåg, Steffen (Doctoral thesis; Doktorgradsavhandling, 30-Jan-2012)[+][-]
Abstract: MapReduce has become a widely employed programming model for large-scale data-intensive computations. Traditional MapReduce engines employ dynamic routing of data as a core mechanism for fault tolerance and load balancing. An alternative mechanism is static routing, which reduces the need to store temporary copies of intermediate data, but requires a tighter coupling between the components for storage and processing. The initial intuition motivating our work is that reading and writing less temporary data could improve performance, while the tight coupling of storage and processing could be leveraged to improve data locality. We therefore conjecture that a high-performance MapReduce engine can be based on static routing, while preserving the non-functional properties associated with traditional engines. To investigate this thesis, we design, implement, and experiment with Cogset, a distributed MapReduce engine that deviates considerably from the traditional design. We evaluate the performance of Cogset by comparing it to a widely used traditional MapReduce engine using a previously established benchmark. The results confirm our thesis that a high-performance MapReduce engine can be based on static routing, although analysis indicates that the reasons for Cogset's performance improvements are more subtle than expected. Through our work we develop a better understanding of static routing, its benefits and limitations, and its ramifications for a MapReduce engine. A secondary goal of our work is to explore how higher-level abstractions that are commonly built on top of MapReduce will interact with an execution engine based on static routing. Cogset is therefore designed with a generic, low-level core interface, upon which MapReduce is implemented as a relatively thin layer, as one of several supported programming interfaces. At its core, Cogset provides a few fundamental mechanisms for reliable and distributed storage of data, and parallel processing of statically partitioned data. While this dissertation mainly focuses on how these capabilities are leveraged to implement a distributed MapReduce engine, we also demonstrate how two other higher-level abstractions were built on top of Cogset. These may serve as alternative access points for data-intensive applications, and illustrate how some of the lessons learned from Cogset can be applicable in a broader context. Description: The papers of this thesis are not available in Munin:
1. Steffen Viken Valvåg and Dag Johansen: 'Oivos : simple and efficient distributed data processing' (2008). In Proceedings of the 2008 Tenth IEEE International Conference on High Performance Computing and Communications (HPCC 2008), pages 113– 122. IEEE Computer Society. Available at http://dx.doi.org/10.1109/HPCC.2008.105
2. Steffen Viken Valvåg and Dag Johansen: 'Update Maps : a new abstraction for High-Throughput Batch processing' (2009). In Proceedings of the 2009 IEEE International Conference on Networking, Architecture, and Storage (NAS 2009), pages 431–438. IEEE Computer Society. Available at http://dx.doi.org/10.1109/NAS.2009.73
3. Steffen Viken Valvåg and Dag Johansen: 'Cogset : a unified engine for reliable storage and parallel processing' (2009). In Proceedings of the 2009 Sixth IFIP International Conference on Network and Parallel Computing (NPC 2009), pages 174– 181. IEEE Computer Society. Available at http://dx.doi.org/10.1109/NPC.2009.23
4. Steffen Viken Valvåg, Dag Johansen, and Åge Kvalnes: 'Cogset vs. Hadoop : measurements and analysis', (2010). In Proceedings of the 2010 Second IEEE International Conference on Cloud Computing Technology and Science (CloudCom 2010), pages 768–775. IEEE Computer Society. Available at http://dx.doi.org/10.1109/CloudCom.2010.103URI: http://hdl.handle.net/10037/3817 File(s) in this item: 1
thesis.pdf (948.7Kb) -
Haaland, Silje Sanderud (Master thesis; Mastergradsoppgave, Jun-2011)[+][-]
Abstract: Icing on wind turbines are known to lower their performance, but the exact relationship between wind, ice and power production is not known. In this thesis power loss due to icing on turbine blades at Aapua wind park is investigated for the winter season 2009-2010. The total loss is found to be 30%, whereof 25% is concluded being due to icing. Three different methods are presented to estimate a power output model P(V,I), based on empirical data of wind speed, ice load and power production from a wind turbine. The models estimate power output from wind speed and ice load observations. Their performance are compared using correlation and root mean square error (RMSE), and the kriging method, using a weighted mean to calculate power output, is found best. A comparison of the proposed kriging model to an existing model show a 10% increase in performance for the kriging method. Testing shows that kriging works well for low wind speeds and low ice loads, but tends to overestimate production during high ice loads. For the season as a whole, the modelled power output underestimates the power production with 1%. Time series of modelled, measured and expected power output, together with ice load and temperature measurements, are investigated. Results show that sublimation, shedding, melting and accretion processes on the turbine wings, are not fully captured by the model. Mismatch between ice loads on measuring equipment compared to turbine blades, together with insufficient number of observation data, are found to be the main reasons for inaccuracy in the model. URI: http://hdl.handle.net/10037/3814 File(s) in this item: 1
thesis.pdf (2.709Mb)
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