| 1. |
- Alavian Ghavanini, Farzan, 1978, et al.
(författare)
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Vertically aligned carbon based varactors
- 2011
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 110:2
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Tidskriftsartikel (refereegranskat)abstract
- This paper gives an assessment of vertically aligned carbon based varactors and validates their potential for future applications. The varactors discussed here are nanoelectromechanical devices which are based on either vertically aligned carbon nanofibers or vertically aligned carbon nanotube arrays. A generic analytical model for parallel plate nanoelectromechanical varactors based on previous works is developed and is used to formulate a universal expression for their voltage-capacitance relation. Specific expressions for the nanofiber based and the nanotube based varactors are then derived separately from the generic model. This paper also provides a detailed review on the fabrication of carbon based varactors and pays special attention to the challenges in realizing such devices. Finally, the performance of the carbon based varactor is assessed in accordance with four criteria: the static capacitance, the tuning ratio, the quality factor, and the operating voltage. Although the reported performance is still far inferior to other varactor technologies, our prognosis which stems from the analytical model shows a promise of a high quality factor as well as a potential for high power handling for carbon based varactors.
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| 2. |
- Bengtsson, Stefan, 1961, et al.
(författare)
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Carbon-based nanoelectromechanical devices
- 2011
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Ingår i: International Journal of High Speed Electronics and Systems. - 1793-6438. ; 20:1, s. 195-204
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-based nanoelectromechanical devices are approaching applications in electronics. Switches based on individual carbon nanotubes deliver record low off-state leakage currents. Arrays of vertically aligned carbon nanotubes or nanofibers can be fabricated to constitute varactors. Very porous, low density arrays of quasi-vertically aligned arrays of carbon nanotubes behave mechanically as a single unit with very unusual material properties.
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| 3. |
- Bengtsson, Stefan, et al.
(författare)
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Importance of soil type on internal distribution of radiocaesium and radiostrontium in barley, oat and wheat.
- 2012
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Ingår i: 13th International Congress of the International Radiation Protection Association (IRPA) in Glasgow, 13-18 May 2012.
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Konferensbidrag (refereegranskat)abstract
- The release of radionuclides to the atmosphere can result in deposition of the radionuclides directly to terrestrial ecosystems. Following deposition, uptake from soil will also contribute to the activity that is internalized in plants and further transported in the terrestrial ecosystems. These two processes are of concern in the nutrition chains, cereals-bread-human and in feeding stuffs-cow-milk-human. The aim of this study was to quantify the internal distribution of (1) direct wet deposited 134Cs and 85Sr in wheat and (2) root uptake of 137Cs, from Chernobyl accident, in barley and oats, as well as the dependence of distribution on soil type. Wheat crop was grown at the Ultuna meteorological and agricultural field station (Uppsala County) and land management was in accordance with regional agricultural practice. The trial had a randomized block design with 1 × 1 m2 parcels with three replicates. 134Cs and 85Sr were deposited on wheat at three different growth stages by a rainfall simulator. Barley crops was grown at Helganbo (Uppsala County) and Möjsjövik (Uppsala County) and oat crops was grown at Björke (Gävle County), Hille (Gävle County) and Möjsjövik (Uppsala County) all places were in Sweden. Both crops were grown in accordance with regional agricultural practices. Sampling was made in the last growing stage from an area of 1 m2 and the different plant compartments (stem, head, husk and grain) for all crops were dried. Samples were placed in plastic jars and the activity was measured by High Purity Germanium (HPGe) detectors, calibrated for this sample geometry. The preliminary results indicate that the lowest distribution of 137Cs was found to the head and grains of barley and oat grown on loamy clay soil type. There is an indication that the distribution of 134Cs to the head and grains in wheat is not related to the time from the deposition of 134Cs to harvest. It was found to that the distribution of 134Cs to head was higher in the husks then to the grains. For 85Sr it was seen that at a deposition at harvest the highest amount was distributed to the husks compared to the grains. However, at a deposition at the growing stage “flowering” a higher amount was distributed to the head. Factors that influenced distribution of radionuclides were the soil type, type of radionuclide and time interval between deposition and harvest.
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| 4. |
- Bengtsson, Stefan, 1961
(författare)
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Wafer bonding: A retrospective
- 2010
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Ingår i: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781566778237 ; 33:4, s. 429-439
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Konferensbidrag (refereegranskat)abstract
- Wafer bonding has become well-known and widely used as the process of adhesion of two flat mirror-polished wafers without the use of any intermediate adhesive layer. Today, it is used as a versatile tool in a wide variety of scientific fields and the technique has reach industrial maturity in particular for the manufacturing of Silicon-On-Insulator (SOI) materials, but also in other fields, such as for sensors, microsystems, optics and photonics. The early development of wafer bonding is reviewed and a retrospective view is taken on wafer bonding, addressing some of the critical research achievements and breakthroughs over the last three decades. The focus is limited to wafer bonding without the use of adhesive layers or electrostatic fields, and will hence not discuss related techniques, such as anodic bonding.
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| 5. |
- Högman, Ulf, 1961, et al.
(författare)
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Requirements on New Technology and the Technology Implementation Process
- 2010
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Ingår i: 8th International NordDesign Conference, NordDesign 2010; Goteborg; Sweden; 25 August 2010 through 27 August 2010. ; 2, s. 289-300
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Konferensbidrag (refereegranskat)abstract
- In literature, many authors have pointed to the importance of technology and technology development for company competitiveness. In this study we aim to study the technology in more detail and attempt to develop an understanding on the requirements and needs on “technology” from the perspective of product development. The research question which we aim to answer in this study is:“What are the requirements on maturity of technology when this technology is about to enter into the product development process?“A qualitative research strategy, based on three study cases involving 17 interviewees, has been chosen. All three cases come from one single company, Volvo Aero Corporation (VAC) in Sweden, in the context of the aero engine industry. The study contributes with a broad mapping of requirements and how they relate to different categories of technologies, showing big differences both regarding content and timing. It is concluded that attention should be payed both to how the organization builds new capabilities and to the capabilities of the technology itself. A surprisingly complicated picture on the requirements relating to the implementation of new technologies has emerged in the study. This contributes to the understanding regarding the difficulties of developing new technology and integrating it into an application.
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