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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Algorithmica 13 (1995), S. 266-282 
    ISSN: 1432-0541
    Keywords: Graph minors ; NP-completeness ; Planar graphs ; Matching problems ; Treewidth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The computational complexity of a number of problems concerning induced structures in graphs is studied, and compared with the complexity of corresponding problems concerning non-induced structures. The effect on these problems of restricting the input to planar graphs is also considered. The principal results include: (1) Induced Maximum Matching and Induced Directed Path are NP-complete for planar graphs, (2) for every fixed graphH, InducedH-Minor Testing can be accomplished for planar graphs in time0(n), and (3) there are graphsH for which InducedH-Minor Testing is NP-complete for unrestricted input. Some useful structural theorems concerning induced minors are presented, including a bound on the treewidth of planar graphs that exclude a planar induced minor.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 69 (1999), S. 503-527 
    ISSN: 1432-0681
    Keywords: Key words Unilateral contact ; multibody dynamics ; complementarity ; friction ; impact
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary Contact processes may be described by local discretizations, by rigid representation or by mixed methods incorporating both ideas. A rigid body approach is proposed for the dynamics of mechanical systems, achieving good results also for multiple-contact problems. Contacts in multibody systems are mainly considered, with the corresponding contact constraints varying with time, thus generating structure-variant systems. The equations of motion for dynamical systems with such unilateral behavior are discussed, solution methods and applications are presented.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archive of applied mechanics 70 (2000), S. 479-488 
    ISSN: 1432-0681
    Keywords: Key words Traction drive ; friction ; contact ; rheology ; thermal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Summary  In automotive traction drives, power is transmitted by friction forces. The friction forces result from the shear stresses developed in lubricated and highly loaded contacts between rolling bodies. Due to the kinematics of a traction drive, shear velocities occur in both the rolling direction and perpendicular to it. Due to these shear velocities and by normal pressure, the lubricant is forced to build up shear stresses. The increase of the shear stresses may be modelled by a nonlinear viscous element. The describing differential equations are coupled by the equivalent shear stress, which defines the nonlinear behaviour of the element. A fast method is described to evaluate the coupled differential equations. By using a known analytical approximation for the equivalent shear stress, the differential equations are decoupled and can be solved analytically. In an iterative procedure the equivalent shear stress is updated, and the complete solution is found. The iterative method is extended to account for thermal effects in the contact.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Nonlinear dynamics 3 (1992), S. 245-259 
    ISSN: 1573-269X
    Keywords: Unilateral contacts ; constrained motion ; friction ; impacts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In the following a percussion drilling machine is examined as an example for mechanical systems with unilateral contacts. It is characteristic for such systems that the number of degrees of freedom changes during motion. To avoid a description of each possible system state using different sets of minimal coordinates, the constrained motion is taken into account by algebraic relations. This method has the advantage that the motion of the system and simultaneously the constraint forces are available, which is necessary to obtain conditions for a change in the state of the system. Furthermore different combinations of constraints can be easily taken into consideration in this way.
    Type of Medium: Electronic Resource
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