| 1. |
- Berntsson, Thore, 1947, et al.
(författare)
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Towards Sustainabel Oil Refinery - Pre-study for larger co-operation project
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this report, the Chalmers EnergiCentrum (CEC) presents the results of a pre-study commissioned by Preem relating to the effective production of future vehicle fuels.This pre-study was made up of three studies focusing on energy streamlining, the utilisation of waste heat and carbon-dioxide separation and biorefinement relating to the gasification and hydration of vegetable oils. One of the common starting points for these studies was the current situation at the Preem refineries in Göteborg and Lysekil from where the measurement data were obtained and analysed. The report summarises the knowledge situation based on current research in the individual technical fields. The results present some interesting future opportunities for developing the sustainable production of future vehicle fuels. The sections vary, as the areas that have been examined differ and the sections have been written by different people. The reports ends with some joint conclusions and a number of questions which could be included and answered in a more extensive future main study, as part of a developed research partnership between Preem and the Chalmers University of Technology. The preliminary results of this work were analysed with the client at workshops on 1 October and 29 November 2007. The report is written in English combined with an extensive summary in Swedish including a proposal on a future main study. The study was conducted by the Chalmers EnergiCentrum (CEC), in collaboration with a number of researchers in the CEC’s network. They included Thore Berntsson, Jessica Algehed, Erik Hektor and Lennart Persson Elmeroth, all from Heat and Power Technology, Börje Gevert, Chemical and Biological Engineering, Tobias Richards, Forest Products and Chemical Engineering, Filip Johnsson and Anders Lyngfelt, Energy Technology, and Per-Åke Franck and Anders Åsblad, CIT Industriell Energianalys AB. The client, Preem, was represented by Bengt Ahlén, Sören Eriksson, Johan Jervehed, Bertil Karlsson, Gunnar Olsson, Ulf Kuylenstierna, Stefan Nyström, Martin Sjöberg and Thomas Ögren. Tobias Richards was responsible for compiling the report and Bertil Pettersson was the project manager.
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| 2. |
- Bryngelsson, David, 1981, et al.
(författare)
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The effect of food-price movements on African households - An investigation of food production and consumption patterns in four African countries
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The recent spike in world food prices has intensified the debate regarding the impact of food prices on poverty. In this paper we aim to assess households’ vulnerability to food-price increases in four countries in Sub-Saharan Africa. Using household data from the World Bank’s Living Standard Measurement Surveys in Ghana (2005–2006), Kagera region, Tanzania (2004), Malawi (2004–2005) and South Africa (1993) we analyze food production and consumption patterns in rural and urban populations. We use two established indicators of sensitivity to food price changes—one measuring the share of income spent on food, the other measuring net sales of food compared to total expenditures. We find that the shares of the populations spending more than half of their income on food ranges from 62–81% in rural areas and from 26–67% in urban areas. Further we find that in all regions studied, most households (74–99%) in rural areas are net buyers of food and stand to lose in the short term from higher food prices. As expected, for urban households this is true to an even higher extent. In contrast to earlier studies we look at all food items and not just one or a few staple foods, giving a better understanding of vulnerability to general food price changes. We find that the exclusion of non-staple foods has a significant impact on theresults.
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| 3. |
- Larsson, Bengt, et al.
(författare)
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Molecular oxygen in the rho Ophiuchi cloud
- 2007
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 466:3, s. 5-
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Tidskriftsartikel (refereegranskat)abstract
- Context: Molecular oxygen, O2, has been expected historically to be an abundant component of the chemical species in molecular clouds and, as such, an important coolant of the dense interstellar medium. However, a number of attempts from both ground and from space have failed to detect O2 emission.Aims: The work described here uses heterodyne spectroscopy from space to search for molecular oxygen in the interstellar medium. Methods: The Odin satellite carries a 1.1 m sub-millimeter dish and a dedicated 119 GHz receiver for the ground state line of O2. Starting in 2002, the star forming molecular cloud core ρ Oph A was observed with Odin for 34 days during several observing runs.Results: We detect a spectral line at v_LSR =+3.5 km s-1 with Δ v_FWHM=1.5 km s-1, parameters which are also common to other species associated with ρ Oph A. This feature is identified as the O2 (NJ = 11 - 1_0) transition at 118 750.343 MHz.Conclusions: The abundance of molecular oxygen, relative to H{2} , is 5 × 10-8 averaged over the Odin beam. This abundance is consistently lower than previously reported upper limits.Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Étude Spatiale (CNES). The Swedish Space Corporation has been the industrial prime contractor and also is operating the satellite. Appendix A is only available in electronic form at http://www.aanda.org
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| 4. |
- Melin, Jonas, et al.
(författare)
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Microreplication in a Silicon Processing Compatible Material
- 2005
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Ingår i: IEEE/LEOS Optical MEMS 2005: International Conference on Optical MEMS and Their Applications, Oulu, Finland, 1-4 August 2005. - 9780780392786 ; , s. 89-90
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Konferensbidrag (refereegranskat)abstract
- We present a novel fabrication process for the integration of polymer micro-optical elements on silicon. The process relies on a reverse order protocol based on embossing in an amorphous fluorocarbon polymer, Cytop™.
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| 6. |
- Persson, Anders, 1975, et al.
(författare)
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A unified analysis for coded DS-CDMA with equal-gain chip combining in the downlink of OFDM systems
- 2005
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Ingår i: IEEE Transactions on Communications. - 0090-6778 .- 1558-0857. ; 53:2, s. 289-298
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel unified analysis for the bit-error rate in the downlink of convolutionally coded and single-user detected multicarrier code-division multiple access (CDMA), multicarrier direct-sequence CDMA, time and frequency-domain spreading CDMA, and orthogonal frequency-division multiple access. Performance is analyzed under the assumption of Hadamard spreading codes, equal-gain chip combining, and a highly correlated frequency-selective Rayleigh-fading channel. Closed-form expressions are presented for the cumulative distribution function, probability distribution function, and moment-generating function for the signal-to-noise plus interference ratio after despreading. The presented results assume error-free channel estimates, a perfectly synchronized receiver, and are found to reasonably well agree with simulation results. © 2005 IEEE.
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| 9. |
- Persson, Martin, 1979, et al.
(författare)
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Computer Generated Holograms Designed to Reduce Intensity Fluctuations During SLM Update
- 2009
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Ingår i: Digital Holography and Three-Dimensional Imaging, OSA Technical Digest (CD). - Washington, D.C. : OSA. - 2162-2701. ; , s. DWC3-
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Konferensbidrag (refereegranskat)abstract
- We have investigated design criteria for calculation of computer generated holograms, aiming to reduce the deterioration of the spot pattern during SLM updates. A modified Gerchberg-Saxton algorithm that efficiently minimizes unwanted intensity fluctuations is introduced.
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