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- Näsman, Olof, 1943-
(författare)
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Samhällsmuseum efterlyses : Svensk museiutveckling och museidebatt 1965–1990
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A new cultural policy developed in Sweden in the 1960’s in order to renew the activities of mseums in a more socially relevant direction. The dissertation examines whether the museums adopted the new policy and to what extent the objectives were achieved. The thesis analyses three main areas: the new cultural policy and the attempts to implement it; activities in selected museums along with different intellectual trends that shaped their activities; and the debate between different “thought collectives” (L. Fleck) regarding museums’ missions and objectives as well as expectations within the museum sector. How did the various “actors” relate to the objectives of the new cultural policy? The thesis confirms the potential of the museums as generators for renewal and innovation in terms of democracy and development of the society. There was a clear shift in attitudes from values associated with the “Cultural heritage museum” towards the in this thesis introduced idea of the “Community museum”. The study shows how museums tried to introduce activities relating to current political and social issues, which supports the principal hypothesis in the study, that the museums became more socially relevant during the investigated period. However, during the 1980s, there could be seen a clear recurrence back to the idea of “Cultural heritage museum”. The movement in opposite directions illustrates the museums’ strong ties to the earlier traditional ”styles of thought” (Fleck) and their role as cultural guardians, which severely restricted their capacity for innovation and new ways of thinking.Nevertheless, the Swedish Exhibition Agency (Riksutställningar) performed a role as a searhead for the new cultural policy, corresponding with the heterodoxy and new style of thinking represented by the “Community museum”. A number of persons dominating the debate within the museum sector had a crucial importance in the shift towards the concept of “Community museums”. A revitalisation of the exhibitions, pedagogy and content was accomplished, often as a result of the Swedish Exhibition Agency’s efforts to develop the medium. During the period 1965–1990 Swedish museum exhibitions moved towards a temporary and more socially oriented content. According to Steven Conn’s principal thesis “Do museums still need objects?” the importance of objects gradually declined during the last century. In line with this development, the new Museum of Work had no objects/collections of its own. Furthermore, the arrival of new technology in the late 1980’s gave preconditions for reshaping knowledge and contributed to new attitudes towards communication. Museums were now seen as centres for social contact and communication.The role of museology as an academic discipline in the reprogramming of the museums towards a more socially oriented approach is another important issue. Museology has been criticized by those who – int the debate – questioned the entire idea of “Community museum”.
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- Westerling, Lars, 1943-
(författare)
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Interaction of Cylindrical Penetrators with Ceramic and Electromagnetic Armour
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Armoured vehicles have traditionally used steel armour as protection against penetrators such as projectiles and shaped charge jets. The latter produce a thin stretching metal jet, usually of copper, with a tip velocity of about 7-8 km/s. In order to obtain more weight-efficient solutions, there is a search for lighter materials and other protection techniques. In this thesis, ceramic and electromagnetic armours are studied. Ceramic materials are lighter than steel, and their high compressive strength makes them useful as armour materials. Electromagnetic armour consists of two metal plates connected to an electric power supply capable of delivering a strong current pulse. A conductive penetrator passing through both plates is destroyed by the effects of the resulting current.Tests of the ceramic armour materials alumina and boron carbide were performed with reverse impact technique, which signifies that a target assembly (ceramic confined in a metal cylinder) was launched by a gun towards a projectile placed in front of the gun barrel. By this technique yaw was eliminated, but the geometric scale had to be very small. Therefore, we studied scaling laws for ceramic armour through a series of tests with direct impact technique and projectile diameters from 2 to 10 mm. The small scale has the advantage that flash X-ray photography can be used to photograph the projectile inside the ceramic target. The phenomenon of interface defeat or dwell was also demonstrated. It signifies that the ceramic, at least for a short time, can withstand the impact pressure so that the projectile just flows out onto the target surface. A transition velocity, above which dwell does not occur, was determined. Simulations were performed with the continuum-dynamic code Autodyn and by use of a model for the brittle ceramic materials by Johnson and Holmquist. The simulations reasonably well represented the penetration behaviour above the transition velocity. They also did below, if under this condition the ceramic model was forced to remain undamaged.The performance of electromagnetic armour was tested against a shaped charge jet. The jet was registered with shadowgraph flash X-ray photography between the plates and after passing through the plates. The current through the jet and the voltage over the plates were also registered. The current caused heating leading to melting and even vaporization. The magnetic Lorentz force compressed the jet radially, and as this effect increases with decreasing jet radius, instability may arise. Explosions in the compressed regions resulted in a fragmented jet with disk-shaped fragments which are less effective penetrators than the elongated fragments obtained in the absence of current. We also performed a theoretical study, in which the penetrator was subjected to small elastic strains only and the current was constant. The magnetic field was determined by FFT, and the stresses due to the Lorentz force were calculated with a semi-analytical method. The velocity skin effect was demonstrated.
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