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- Brage, Tomas, et al.
(författare)
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Hyperfine induced transitions as diagnostics of isotopic composition and densities of low-density plasmas
- 1998
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 500:1, s. 507-521
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Tidskriftsartikel (refereegranskat)abstract
- The J = 0 --> J' = 0 radiative transitions, usually viewed as allowed through two-photon decay, may also be induced by the hyperfine (HPF) interaction in atoms or ions having a nonzero nuclear spin. We compute new and review existing decay rates for the nsnp P-3(J)0 --> nS(2 1)S(J'= 0) transitions in ions of the Be (n = 2) and Mg (n = 3) isoelectronic sequences. The HPF induced decay rates for the J = 0 --> J' = 0 transitions are many orders of magnitude larger than those for the competing two-photon processes, and when present are typically 1 or 2 orders of magnitude smaller than the decay rates of the magnetic quadrupole (J = 2 --> J' = 0) transitions for these ions. Several HPF induced transitions are potentially of astrophysical interest in ions of C, N, Na, Mg, Al, Si, K, Cr, Fe, and Ni. We highlight those cases that may be of particular diagnostic value for determining isotopic abundance ratios and/or electron densities from UV or EUV emission-line data. We present our atomic data in the form of scaling laws so that, given the isotopic nuclear spin and magnetic moment, a simple expression yields estimates for HPF induced decay rates. We examine some UV and EUV solar and nebular data in light of these new results and suggest possible applications for future study. We could not find evidence for the existence of HPF induced lines in the spectra we examined, but we demonstrate that existing data have come close to providing interesting upper limits. For the planetary nebula SMC N2, we derive an upper limit of 0.1 for C-13/C-12 from Goddard High-Resolution Spectrograph data obtained by Clegg. It is likely that more stringent limits could be obtained using newer data with higher sensitivities in a variety of objects.
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- Engström, Tomas, 1950, et al.
(författare)
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Alternatives to Line Assembly: Some Swedish examples
- 1996
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Ingår i: International Journal of Industrial Ergonomics. - 1872-8219 .- 0169-8141. ; 17:3, s. 235-245
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, some criticism of Lean production has occurred, focusing among other things on the working conditions and the susceptibility of traditional assembly work in a society upgrading the demands for a more humanized work. Recently, this criticism has also concerned the technical aspects of this type of manufacturing. Because of this, alternatives to line assembly merit some attention. Experiences from some innovative production systems operated in the Swedish automotive industry during the last two decades are of particular interest. These unconventional production systems feature autonomous work groups and extended work cycles. These types of production systems are elucidated in detail by means of e.g nuance the concept of utilising buffers, i.e. there are different types of buffers (or buffer functions) as is classified (or clarified) in this publications.
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- Engström, Tomas, 1950, et al.
(författare)
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Automotive Industry
- 1997
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Ingår i: The Workplace – Major industries and occupations, Vol. 2, Brune, D., Gerhardsson, G., Crockford, G. W. and Norbäck, D. (eds.), International Occupational Safety and Health Information Centre (CIS), International Labour Office Geneva, Scandinavian Science Publisher, Oslo. ; , s. 548-565
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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- Engström, Tomas, 1950, et al.
(författare)
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Developments in Assembly System Design: The Volvo Experience
- 1999
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Ingår i: Coping with Variety: Flexible Production Systems for Product Variety in the Automobile Industry; Lung, Y., Chanaron, J. J., Fujimoto, T. and Raff, D. (eds.); Ashgate, Aldershot. - : Routledge. - 9780429839931 ; , s. 192-223
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on experiences concerning the development of assembly systems within the Volvo Corporation. It provides research and development work within the Swedish automotive industry. The chapter considers a specific trajectory concerning assembly system design in the Swedish automobile industry, generalising the Volvo Kalmar and Volvo Uddevalla experiences. During 1988–1990, the managers at Volvo were planning the manufacturing of the new 800 model at the main Volvo Torslanda plant, as well as looking for a total redesign of the plant. The average product quality in the Uddevalla plant was high–in fact better than in Volvo's line assembly plants–but the product quality varied considerably. Productivity and flexibility proved to be superior to traditional serialassembly systems. Two ways of decreasing the time losses are to introduce parallel flow assembly systems–that is assembly systems consisting of many, short, unpaced flows–or to introduce buffers between work-stations.
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- Engström, Tomas, 1950, et al.
(författare)
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Empirical Evaluation of the Reformed Assembly Work at the Volvo Uddevalla Plant. Psychosocial effects and performance aspects
- 1995
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 1872-8219 .- 0169-8141. ; 16:16, s. 293-308
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports on the innovative, now defunct, Volvo Uddevalla final assembly plant. Theoretical frames of reference, the design process and empirical data on workgroup characteristics and working conditions are focused upon. Information regarding the Uddevalla plant has been gathered during a long-term co-operation project with the Volvo Corporation. During the closing-down period, we obtained full access to all the production engineering data and personnel files available. We also had the opportunity of studying the responses to a questionnaire distributed to a random sample of blue-collar workers. Working conditions in Uddevalla in the form of psychosocial job factors are compared with industrial blue-collar workers in general as well as with assembly workers in the closed down Volvo Kalmar final assembly plant, which had a different, more traditional, production system. The paper also compares the psychosocial job factors, performance measures and work-group characteristics in the five assembly workshops in the Uddevalla plant. In comparing assembly workshops, the paper contrasts two approaches to competence development and work structuring used in Uddevalla, namely (1) giving priority to the individual in-depth training of a specific task or (2) giving priority to a large competence overlap between individuals in a workgroup. Relevance to the industry. This paper reports and explains some results from a multidisciplinary evaluation of shop-floor work in the Volvo Uddevalla plant, a full-scale assembly plant with a parallelized flow and long cycle time, using autonomous work groups. These experiences should be of general interest to industries searching for the factory of the future.
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