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- Filla, Reno, 1973-
(författare)
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Operator and Machine Models for Dynamic Simulation of Construction Machinery
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- VIRTUAL PROTOTYPING has been generally adopted in product development in order to minimise the traditional reliance on testing of physical prototypes. It thus constitutes a major step towards solving the conflict of actual increasing development cost and time due to increasing customer demands on one side, and the need to decrease development cost and time due to increasing competition on the other. Particularly challenging for the off-road equipment industry is that its products, working machines, are complex in architecture. Tightly coupled, non-linear sub-systems of different technical domains make prediction and optimisation of the complete system’s dynamic behaviour difficult.Furthermore, in working machines the human operator is essential for the performance of the total system. Properties such as productivity, fuel efficiency, and operability are all not only dependent on inherent machine properties and working place conditions, but also on how the operator uses the machine. This is an aspect that is traditionally neglected in dynamic simulations, because the modelling needs to be extended beyond the technical system.The research presented in this thesis focuses on wheel loaders, which are representative for working machines. The technical system and the influence of the human operator is analysed, and so-called short loading cycles are described in depth. Two approaches to rule-based simulation models of a wheel loader operator are presented and used in simulations. Both operator models control the machine model by means of engine throttle, lift and tilt lever, steering wheel, and brake only – just as a human operator does. Also, only signals that a human operator can sense are used in the models. It is demonstrated that both operator models are able to adapt to basic variations in workplace setup and machine capability. Thus, a “human element” can be introduced into dynamic simulation of working machines, giving more relevant answers with respect to operator-influenced complete-machine properties such as productivity, fuel efficiency, and operability already in the concept phase of the product development process.
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- Larsson, K, et al.
(författare)
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Inhalation of cold air increases the number of inflammatory cells in the lungs in healthy subjects
- 1998
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Ingår i: The European respiratory journal. - : European Respiratory Society (ERS). - 0903-1936 .- 1399-3003. ; 12:4, s. 825-830
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Tidskriftsartikel (refereegranskat)abstract
- Prolonged exposure to cold air may induce a chronic asthma-like condition in healthy subjects as has been demonstrated in cross-country skiers. In the present controlled study, our aim was to elucidate further the link between cold air exposure and airway inflammation by assessing the cellular influx and mediator levels within the airways following acute exposure to cold air. Bronchoalveolar (BAL) and nasal lavages were performed after exposure to cold air (-23 degrees C) and normal indoor air (+22 degrees C) during a light, intermittent work for 2 h in a cross-over design in eight healthy, nonsmoking, subjects. Analyses of inflammatory cell number, cell activation markers, pro-inflammatory cytokines, albumin and interleukin (IL)-8 in lavage fluids were performed. The number of granulocytes and of alveolar macrophages in BAL fluid was significantly higher after cold air exposure (p<0.05). No increase in BAL fluid lymphocytes and no signs of lymphocyte activation in BAL fluid were found. The concentration of IL-8 was unchanged. There were no signs of granulocyte activation (myeloperoxidase, eosinphilic cationic protein) in BAL fluid. Cold air did not influence the number of inflammatory cells or the concentration of albumin and IL-8 in nasal lavage fluid. In conclusion, exposure to cold air induces an increased number of granulocytes and macrophages in the lower airways in healthy subjects without influencing other inflammatory indices such as cellular activation, plasma leakage and pro-inflammatory cytokines. These findings support the hypothesis that cold air could be of pathogenetic importance in the asthma-like condition previously found in cross-country skiers.
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