3,400 research outputs found
What can be inferred from surrogate data testing?
Surrogate data testing for linearity is frequently applied to confirm the
results of nonlinear time series analysis. We argue that this, in general, is
not possible.Comment: 1 pag
On robustness and dynamics in (un)balanced coalitional games
We build upon control theoretic concepts like robustness and dynamics to better accommodate all the situations where the coalitionsā values are uncertain and subject to changes over time. The proposed robust dynamic framework provides an alternative perspective on the study of sequences of coalitional games or interval valued games. For a sequence of coalitional games, either balanced or unbalanced, we analyze the key roles of instantaneous and average games. Instantaneous games are obtained by freezing the coalitionsā values at a given time and come into play when coalitionsā values are known. On the other hand, average games are derived from averaging the coalitionsā values up to a given time and are key part of our analysis when coalitionsā values are unknown. The main theoretical contribution of our paper is a design method of allocation rules that return solutions in the core and/or -core of the instantaneous and average games. Theoretical results are then specialized to a simulated example to shed light on the impact of the design method and on the performance of the resulting allocation rules
Cooperation in stochastic inventory models with continuous review
Consider multiple companies that continuously review their inventories and face Poisson demand. We study cooperation strategies for these companies and analyse if there exist allocations of the joint cost such that any company has lower costs than on its own; such allocations are called stable cost allocations. We start with two companies that jointly place an order for replenishment if their joint inventory position reaches a certain reorder level. This strategy leads to a simple expression of the joint costs. However, these costs exceed the costs for non-cooperating companies. Therefore, we examine another cooperation strategy. Namely, the companies reorder as soon as one of them reaches its reorder level. This latter strategy has lower costs than for non-cooperating companies. Numerical experiments show that the gametheoretical distribution rule ā a cost allocation in which the companies share the procurement cost and each pays its own holding cost ā is a stable cost allocation. These results also hold for situations with multiple companies
Cross-spectral analysis of physiological tremor and muscle activity. I. Theory and application to unsynchronized EMG
We investigate the relationship between the extensor electromyogram (EMG) and
tremor time series in physiological hand tremor by cross-spectral analysis.
Special attention is directed to the phase spectrum and the effects of
observational noise. We calculate the theoretical phase spectrum for a second
order linear stochastic process and compare the results to measured tremor data
recorded from subjects who did not show a synchronized EMG activity in the
corresponding extensor muscle. The results show that physiological tremor is
well described by the proposed model and that the measured EMG represents a
Newtonian force by which the muscle acts on the hand.Comment: 9 pages, 6 figures, to appear in Biological Cybernetic
Confirmation of the 62 Day X-Ray Periodicity from M82
Using 400 days of new X-ray monitoring of M82, we confirm the 62 day
periodicity previously reported. In the full data set spanning 1124 days, we
find a period of 62.0 +/- 0.3 days and a coherence, Q = 22.3, that is
consistent with a strictly periodic signal. We estimate that the probability of
chance occurrence of our observed signal is 6E-7. The light curve folded at
this period is roughly sinusoidal and has a peak to peak amplitude of (0.99 +/-
0.10) x 10^-11 erg cm^-2 s^-1. Confirmation of the periodicity strengthens our
previous suggestion that the 62 day modulation is due to orbital motion within
an X-ray binary.Comment: 4 pages, to appear in Ap
The approximate f-core and the utopia payoff for infinite assignment games
Assignment problems where both sets of agents are countably infinite, the so-called infinite assignment problems, are studied as well as the related assignment games. Further, two solutions for these games are studied. The first one is the approximate f-core for games with a finite value. This particular solution takes into account that due to organisational limitations only finite groups of agents can protest against proposals of profit distributions. Second, we study the utopia payoff, the perfect proposal in which each agent receives the maximal amount he can get. \u
The Effect of Various Deinking Solutions and Concentrations Upon the Strength of Fiber
Preliminary investigation produced limited information on the effect of various deinking solutions and concentrations upon the strength of fiber. Experimentation indicated that deinking does have a destructive effect upon the strength of fiber. This effect correlates to the temperature and the amount of chemical used. Also indicated is the fact that a mixture of Sodium hydroxide and Sodium carbonate has less of a destructive effect than either of these alone
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