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| 2. |
- Bryllert, Tomas, 1974, et al.
(författare)
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220-GHz imaging radar with 1 Hz frame rate using an array of homodyne transceivers
- 2018
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 10634
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Konferensbidrag (refereegranskat)abstract
- We present a 220 GHz imaging radar prototype that has been developed in the European Defense Agency (EDA) project TIPPSI. The purpose of the development was to demonstrate short-range high-resolution 3D imaging for security applications at checkpoints, and to guide the development of stand-off real-time millimeter wave and sub-millimeter wave imaging systems for detection of larger objects at greater distances. An additional goal was to experimentally verify simulation techniques for active (sub)-mmw imaging systems, the verified simulation techniques can then be used to explore different system architectures. The 220 GHz imaging radar prototype consist of a flexible, mechanically scanned optical system that can support linear arrays of transmit/receive (TxRx) units up to 150 mm in length. The optical system is divided into two parts: A compact Dragonian system including the mechanical scanner that can be used as a stand-alone imager at reduced target distance and resolution, and a confocal system that can be added to achieve the full resolution of 1 cm x 1 cm x 1 cm at 4.5 m target distance. The field of view of the full resolution system is 70 cm x 70 cm. The front-end is currently populated by 4 TxRx units that are sparsely distributed along the 150 mm focal plane. The TxRx units operate in frequency modulated continuous wave (FMCW) mode and have a bandwidth of 24 GHz. Each TxRx unit use a single horn antenna and the transmit- and receive signals are generated and received using the same circuits which avoids the need of a duplexer. We will demonstrate high resolution 3D videos taken at 1 Hz frame rate and compare the individual images with simulations using electromagnetic simulators and character/clothes animation.
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| 3. |
- Giles, Tim, et al.
(författare)
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Cost Drivers and Deployment Scenarios for Future Braodband Wireless Networks - Key research problems and directions for research
- 2004
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Ingår i: VTC2004-SPRING. - New York : IEEE. - 0780382552 ; , s. 2042-2046
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Konferensbidrag (refereegranskat)abstract
- The most prominent problem in providing anywhere, anytime wideband mobile access is the towering infrastructure cost as it is basically proportional to the bandwidth provided. In this paper, we provide a simple, initial, analysis of the various infrastructure cost factors. This analysis shows that, contrary to what one may expect, the infrastructure cost is not dominated by electronic equipment, but rather by other deployment related costs (towers, wiring, building, network connections) and maintenance costs. In the paper some novel architectural approaches for future wideband mobile access focusing on these dominant cost factors are described and the related key research issues are discussed.
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| 5. |
- Karlsson, Martin, et al.
(författare)
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Rotor dynamical analysis of a hydroelectric generator for active power
- 2006
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Ingår i: Proceedings. - Singapore : Aqua-Media International.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Asymmetry of the magnetic field in a synchronous generator will induce a magnetic unbalance pull. In this paper, a hydropower rotor system is modelled and the influence of electro-mechanical forces due to different amounts of real power is analysed. The electromagnetic field is solved with the finite element method and coupled with mechanical system as a magnetic stiffness. The mechanical model of the generator consists of a four degree of freedom rigid disc connected to an elastic shaft supported by two bearings with linear properties. It has been found that the unbalance magnetic pull increases for a lover amount of real power leading to a decrease of natural frequencies and an increase of unbalance response. Since many hydropower units are used for both part and full load it becomes important to model the electro-mechanical interaction when developing new generators, in order to improve the mechanical design.
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| 7. |
- Ahlström, Christer, 1977-, et al.
(författare)
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Assessment of Suspected Aortic Stenosis by Auto Mutual Information Analysis of Murmurs
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. - 9781424407873 ; , s. 1945-1948
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Konferensbidrag (refereegranskat)abstract
- Mild sclerotic thickening of the aortic valve affects 25% of the population, and the condition causes aortic valve stenosis (AS) in 2% of adults above 65 years. Echocardiography is today the clinical standard for assessing AS. However, a cost effective and uncomplicated technique that can be used for decision support in the primary health care would be of great value. In this study, recorded phonocardiographic signals were analyzed using the first local minimum of the auto mutual information (AMI) function. The AMI method measures the complexity in the sound signal, which is related to the amount of turbulence in the blood flow and thus to the severity of the stenosis. Two previously developed phonocardiographic methods for assessing AS severity were used for comparison, the murmur energy ratio and the sound spectral averaging technique. Twenty-nine patients with suspected AS were examined with Doppler echocardiography. The aortic jet velocity was used as a reference of AS severity, and it was found to correlate with the AMI method, the murmur energy ratio and the sound spectral averaging technique with the correlation coefficient R = 0.82, R = 0.73 and R = 0.76, respectively.
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| 8. |
- Aidanpää, Jan-Olov, et al.
(författare)
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Developments in rotor dynamical modeling of hydropower units
- 2009
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Ingår i: Proceedings of the IUTAM Symposium on Emerging Trends in Rotor Dynamics. - Dordrecht : Encyclopedia of Global Archaeology/Springer Verlag. - 9789400700192
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Konferensbidrag (refereegranskat)
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| 9. |
- Alpenberg, Jan, 1964-, et al.
(författare)
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Municipal managers and the use of capital investment methods in decision-making
- 2019
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Ingår i: Presented at the 15th Asia Pacific Management Accounting Association Annual Conference, Doha, Qatar, November 2-5, 2019. - : Asia Pacific Management Accounting Association.
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Konferensbidrag (refereegranskat)abstract
- Capital investments in the public sector counts for large amount of spending every year and municipalities have a responsibility to allocate resources both cost effective and efficiently in order to achieve societal benefit for the citizens. Well-prepared assessment data and a structured and stable project routine should therefore be expected to form an important basis for investment project assessment. Based on previous studies however, uniform investment assessment decision logic has not been clearly identified and thoroughly explained. Previous research on municipality organizations shows even the existence of parallel, sometimes contradicting decision logics. Capital investments in municipal organizations can therefore be concluded as a still relatively undiscovered, but important knowledge area within the investment field, both from a theoretical and practical viewpoint.This study can thus be seen as an in depth case study trying to further line out and explain investment practice documented in the previous research and focus on how investment decisions are conducted and related to how the propulsion process of new investments are organized in Swedish municipal organizations. The overall purpose with the study is to increase the understanding and explanations on how Swedish municipalities use assessment data for initiation, integration and decision making of large projects, in the light of the different decision logics that seem to be prevalent in the investments practice of municipal organizations.
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