Results 271 to 280 of about 8,002,154 (311)

Variational Methods for Periodic Lattices

Physical Review, 1952
The problem of finding the propagating solutions of the Schr\"odinger equation in periodic lattices is formulated as a variational principle. This may be used as a starting point to establish the general properties of bands. Furthermore it is shown that by introducing various approximations into the variational principle, the chief existing ...
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Periodic variations in micropulsation dominant period

Physics of the Earth and Planetary Interiors, 1969
Abstract Power density spectra of consecutive hourly values of the dominant period of micropulsations in the period range 10 seconds to 200 seconds have been computed in order to detect periodic variations in the dominant period. Three magnetic field variation components and three Earth current components recorded for an interval of 336 hours were ...
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New period and period variations of DX Aquarii

Astrophysics and Space Science, 1986
The new period (P=0.d461700) of the eclipsing binary system DX Aqr has been presented, which is based on available times of minima. O−C diagram of DX Aqr has been presented for the first time, and the period variations present in the system have been analysed.
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Periodic solutions of arbitrary period, variational methods

2006
We have constructed by a rapidly convergent variational method the periodic solutions, analytic in the time t and with “arbitrary” (long) period, of the well known Henon-Heiles System, described by the Hamiltonian: \(H = \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/\kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} (\dot x^2 + \dot y^2 + x^2 + y^2 ) + x^2 y -
Robert H. G. Helleman, Tassos Bountis
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Periodic variation of preloading in ball screws

Production Engineering, 2010
The preloading is a main characteristic for the functionality of a ball screw. The path of preloading during operation with no thrust load is an indicator for the actual inner forces, the friction produced by the ball screw and finally for the quality of the unit.
Siegfried Frey, Michael Walther, Alexander Verl   +2 more
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[Periodic breathing with periodic oxygen variation in infancy].

Wiener medizinische Wochenschrift (1946), 1997
Oxycardiorespirographies, recording arterial oxygen saturation (SaO2), breathing movements, heart rate and ECG with a mean recording time of 22.3 hours, were performed on 85 preterm (mean postconceptional age: 38 weeks) and 81 term infants (mean postconceptional age 42.4 weeks).
G, von Czettritz, R T, Bax, T, Eckardt, S, Springer, P, Emmrich   +4 more
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ON QUASI-PERIODIC VARIATIONS OF COSMIC RAYS

2012
Selected results of experimental studies of quasi-periodic variations of cosmic rays obtained from ground based measurements, especially from neutron monitor Climax, are reviewed. At high frequencies the dominant periodicity is the solar diurnal variation and its higher harmonics.
Kudela, K, Bobik, P, BOELLA, GIULIANO FILIPPO, Boschini, MJ, CONSOLANDI, CRISTINA, Della Torre, S, GERVASI, MASSIMO, Grandi, D, PENSOTTI, SIMONETTA, Rancoita, PG, TACCONI, MAURO   +10 more
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The period variation of DY Hercules

Astrophysics and Space Science, 2007
In this paper the researchers collected 28 times of maximum light including 4 times of those observed at the Xinglong station, the National Astronomical Observation of China between May 27, 2004 and June 1, 2004 and 1 time of maximum light from a 60 cm telescope on May 4, 1984.
Chayan Boonyarak, Shi Yang Jiang
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Non Stationary Bandits with Periodic Variation

International Joint Conference on Autonomous Agents and Multiagent Systems
In numerous real-world scenarios, we encounter periodic patterns in the dynamics of non-stationary data. Unfortunately, current approaches to addressing non-stationary bandit problems overlook the valuable potential offered by the presence of periodicity. In response, we introduce SW-PUCB, a novel sliding window algorithm explicitly designed to exploit
Titas Chakraborty, Parth Shettiwar
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Expectation and Variation in Multi-Period Decisions

Econometrica, 1989
Multi-period decisions are decisions which determine an individual's payoffs in several periods in the future. This paper examines the theoretical foundations of the prevalent weighted average assumption. More specifically, we use a multi-period interpretation of the famous Ellsberg paradox in decision under uncertainty to show that in many cases of ...
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