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| 4. |
- Andersson, Sören, et al.
(författare)
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A Study of Adaptive Arrays for Mobile Communication Systems
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The application of adaptive antenna techniques to increase the channel capacity in mobile radio communication is discussed. Directional sensitivity is obtained by using an antenna array at the base station, possibly both in receiving and transmitting mode. A scheme for separating several signals at the same frequency is proposed. The method is based on high-resolution direction finding following by optimal combination of the antenna outputs. Comparisons to a method based on reference signals are made. Computer simulations are carried out to test the applicability of the technique to scattering scenarios that typically arise in urban areas. The proposed scheme is found to have great potential in rejecting cochannel interference, albeit at the expense of high computational requirements.
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| 6. |
- Forsgren, Mats, et al.
(författare)
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Internationalization of division management in Swedish international firms
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- An important issue in the divisionalized firm are the relationsships between the three levels; topmanagement, divisional management and the operational level. In the international firm thephysical location of the divisional management level becomes especially problematic because ofthis level’s strategic role concerning the links to the top management and the foreign subsidiariesrespectively.Most literature on international business leaves no doubt that the parent company, the “centre”,designs the organization and controls the subsidiaries, the “periphery”. However, the relevance ofthis perspective is dependent on the stage of the internationalization process. In later phases ofthis process the subsidiaries can extend their operations to markets outside their own and becomestrong enough to play a strategic role in the group’s total operations within a certain product areaor function. Thus a situation can arise with a firm consisting of several centres located in differentgeographic areas, rather than one centre and a periphery. In the paper this is labeled multi-centrestructure.In a political perspective such centres are expected to have considering influence on the formalorganization structure including the location of the divisional management.In the paper the relation between the internationalization of divisional management and the existence of multi-centre structures in 22 Swedish firms is analysed.
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| 8. |
- Hjalmarsson, Håkan, et al.
(författare)
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How to Estimate Model Uncertainty in the Case of Under-Modelling
- 1990
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Ingår i: Proceedings of the 1990 American Control Conference. - Linköping : Linköping University. ; , s. 323-324
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In System Identification, traditionally, the uncertainty estimate provided with the model is based on the assumption that the model structure used is capable of achieving a correct system description. This estimate is however not correct unless the parameter estimate is close to a "true" model parameter, that yields white noise residuals. The correct expression is known but more complex. The main difficulty, though, is that it is not easily estimated. We suggest a simple and explicit method for estimating the model uncertainty, applicable also to severe under-modelling. The method is illustrated by an example.
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- Kallinikos, Jannis
(författare)
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Techniques of notation and behaviour : remarks on elementary forms of organization
- 1990
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The paper accords signification or representation a decisive role in the context ofinstrumental action. It is argued that the diverse practices subsumed under thenotion of organizing are but varied manifestations of the basic operative schemaof representation: something for something else. Representation is therebyposited as “consubstantial” with the mundane notion of organization. Bothrepresentation and organization imply the institution of diverse systems ofnotation whose mobile, stable and combinable elements enable the making, andby the same token, also the unmaking and remaking of the world. The vicariousand rehearsable character of the representing elements renders the worldmanipulable in the sense of imposing on the sheer flow of experience itscontrived schemata of temporality and distance and its encoded versions ofobjects, states and processes. It establishes the proto-conditions of socialdifferentiation, and hierarchy as it appears in its modern version, by creating in abipolar fashion differences in perspective and knowledge between a centre, i.e.those that encode, accumulate and control combinations of these encodedversions of the world, and a periphery, i.e. local sources of knowledge that arebeing encoded or controlled. However, these ways of worldmaking obey, at leastpartly, the logic enfolded in the forms by means of which a representing universeorganizes and structures its elements. An attempt is made to reveal this logic bydistinguishing different organizing principles falling within the categories ofnumerical, verbal and pictorial representation, and to connect these principles withthe bureaucratic ideal of accountable and calculable behaviour.
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| 10. |
- Ljung, Lennart, 1946-, et al.
(författare)
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Influence of Model Order on Change Detection in Noise-Free Complex Systems
- 1990
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Ingår i: Proceedings of the 1990 American Control Conference. - Linköping : Linköping University. ; , s. 2388-2393
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In all adaptation problems it is essential to estimate the system's (or signal's) characteristics as quickly as possible. There are several design variables that effect this ability. Forgetting factors in recursive algorithms, band-pass filtering to select interesting frequency ranges, and similar, are of major importance for this problem. Also the model order will affect the speed of adaptation since it influences both the "noise" level arising from unmodelled dynamics and the "variance" that depends on the number of estimated parameters. We discuss in this contribution the role of the model order for adaptation. The conclusion is that provided appropriate regularization is applied there are no disadvantages in the use of (very) high order models other than the computational burden.
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