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  • Articles: DFG German National Licenses  (5)
  • 1990-1994  (5)
  • Muscle contraction  (3)
  • Maximin programming  (2)
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  • Articles: DFG German National Licenses  (5)
Material
Years
  • 1990-1994  (5)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Bounded knapsack sharing (1994)
    Springer
    Mathematical programming 67 (1994), S. 343-382 
    Details
    ISSN: 1436-4646
    Keywords: Maximin programming ; Knapsack sharing problems ; Lower and upper bounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A bounded knapsack sharing problem is a maximin or minimax mathematical programming problem with one or more linear inequality constraints, an objective function composed of single variable continuous functions called tradeoff functions, and lower and upper bounds on the variables. A single constraint problem which can have negative or positive constraint coefficients and any type of continuous tradeoff functions (including multi-modal, multiple-valued and staircase functions) is considered first. Limiting conditions where the optimal value of a variable may be plus or minus infinity are explicitly considered. A preprocessor procedure to transform any single constraint problem to a finite form problem (an optimal feasible solution exists with finite variable values) is developed. Optimality conditions and three algorithms are then developed for the finite form problem. For piecewise linear tradeoff functions, the preprocessor and algorithms are polynomially bounded. The preprocessor is then modified to handle bounded knapsack sharing problems with multiple constraints. An optimality condition and algorithm is developed for the multiple constraint finite form problem. For multiple constraints, the time needed for the multiple constraint finite form algorithm is the time needed to solve a single constraint finite form problem multiplied by the number of constraints. Some multiple constraint problems cannot be transformed to multiple constraint finite form problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01582227
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Solving knapsack sharing problems with general tradeoff functions (1991)
    Springer
    Mathematical programming 51 (1991), S. 55-73 
    Details
    ISSN: 1436-4646
    Keywords: Maximin programming ; knapsack sharing problems ; multiple-valued objective functions ; staircase objective functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A knapsack sharing problem is a maximin or minimax mathematical programming problem with one or more “knapsack” constraints (an inequality constraint with all non-negative coefficients). All knapsack sharing algorithms to date have assumed that the objective function is composed of single variable functions called tradeoff functions which are strictly increasing continuous functions. This paper develops optimality conditions and algorithms for knapsack sharing problems with any type of continuous tradeoff function including multiple-valued and staircase functions which can be increasing, decreasing, unimodal, bimodal, or even multi-modal. To do this, optimality conditions are developed for a special type of multiple-valued, nondecreasing tradeoff function called an ascending function. The optimal solution to any knapsack sharing problem can then be found by solving an equivalent problem where all the tradeoff functions have been transformed to ascending functions. Polynomial algorithms are developed for piecewise linear tradeoff functions with a fixed number of breakpoints. The techniques needed to construct efficient algorithms for any type of tradeoff function are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01586926
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Influence of muscle activation dynamics on reaction time in the elderly (1994)
    Springer
    European journal of applied physiology 69 (1994), S. 344-349 
    Details
    ISSN: 1439-6327
    Keywords: Aging ; Electromyography ; Reaction time ; Motor control ; Muscle contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this investigation was to determine whether age-related changes in the dynamics of muscle activation were, in part, responsible for longer reaction times (RT) in the elderly. A group of 12 young (mean age, 20.6 years) and 12 elderly (mean age, 64.3 years) women performed a series of ballistic forearm supination movements in response to an auditory stimulus while using a simple reaction time test. Surface electromyographic waveforms from biceps brachii (agonist) and pronator teres (antagonist) muscles were recorded, together with the angle-time curves representing the motion of the forearm, on to an IBM compatible microcomputer. The results showed that an age-related increase (P〈0.05) in motor reaction time (MRT) contributed to longer RT in the elderly. In addition, the longer (P〈0.05) MRTs in the elderly were associated with a significantly slower rate (P〈0.05) of biceps brachii muscle activation and a significantly increased proportion (P〈0.05) of the initial biceps brachii muscle burst required to initiate the movement. This data suggested that an important part of the slowing of motor behaviour, commonly observed with increasing age, may be due to either decreases in the ability of aged skeletal muscle to rapidly generate tension or to a reduction in motor drive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392041
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Transition from slow to ballistic movement: development of triphasic electromyogram patterns (1991)
    Springer
    European journal of applied physiology 63 (1991), S. 381-386 
    Details
    ISSN: 1439-6327
    Keywords: Motor control ; Electromyography ; Motor skill ; Triphasic electromyogram ; Muscle contraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this investigation was to determine how the triphasic electromyogram (EMG) pattern of muscle activation developed from the agonist muscle only pattern as movement time (t mov) decreased. Six adult women produced a series of 30° elbow extension movements in the horizontal plane at speeds ranging from ballistic (〈 400-ms t mov) to very slow (〉 800-ms t mov). Surface EMG from triceps brachii (agonist) and biceps brachii (antagonist) muscles were recorded, together with elbow angle, on a microcomputer. The results showed that triphasic EMG patterns developed systematically as t mov decreased from 1000 ms to 〈 200 ms. In trials with very long t mov, many elbow extension movements were produced by a single continuous activation of the agonist triceps brachii muscle. As t mov decreased however, agonist activation became predominantly burst-like and other components of the triphasic EMG pattern [activation of the antagonist (Ant) and second agonist activation (Ag2)] began to appear. At the fastest movement speeds, triphasic EMG patterns (Ag1-Ant-Ag2, Ag1 being first activation of agonist muscle) were always present. This data indicated that the triphasic pattern of muscle activation was not switched on when a particular t mov was achieved. Rather, each component systematically developed until all were present, as distinctive bursts of activity, in most trials with t mov less than 400 ms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00364466
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Electromyographic basis of inaccurate movement; its dependence upon the mode of muscle contraction (1991)
    Springer
    European journal of applied physiology 62 (1991), S. 162-170 
    Details
    ISSN: 1439-6327
    Keywords: Motor control ; Electromyography ; Muscle contraction ; Inaccurate movement ; Motor skill
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The electromyographic basis of inaccurate performance was investigated in two rapid precision-grip skills controlled by concentric and eccentric muscle contractions respectively. Surface electromyograms, recorded from the first dorsal interosseous (DI), adductor pollicis (AP) and abductor pollicis brevis, were utilised to identify changes in the timing and intensity of muscle activation which may be responsible for inaccurate performance. The results showed that when fast precision-grip skills were controlled by concentric DI and AP muscle contractions, variations in the intensity of muscle contraction were responsible for inaccurate performance. However, when these skills were controlled by eccentric DI and AP muscle contractions, inaccurate performance resulted from variations in the timing of muscle activation. It was concluded that the nature of the deficiency in the patterns of muscle activation resulting in inaccurate performance was dependent upon the type of muscle contraction used in the skill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00643736
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    Paper (German National Licenses)
    Fulltext
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