• Title/Summary/Keyword: periodic chain

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Stochastic simulation based on copula model for intermittent monthly streamflows in arid regions

  • Lee, Taesam;Jeong, Changsam;Park, Taewoong
    • Proceedings of the Korea Water Resources Association Conference
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    • 2015.05a
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    • pp.488-488
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    • 2015
  • Intermittent streamflow is common phenomenon in arid and semi-arid regions. To manage water resources of intermittent streamflows, stochactic simulation data is essential; however the seasonally stochastic modeling for intermittent streamflow is a difficult task. In this study, using the periodic Markov chain model, we simulate intermittent monthly streamflow for occurrence and the periodic gamma autoregressive and copula models for amount. The copula models were tested in a previous study for the simulation of yearly streamflow, resulting in successful replication of the key and operational statistics of historical data; however, the copula models have never been tested on a monthly time scale. The intermittent models were applied to the Colorado River system in the present study. A few drawbacks of the PGAR model were identified, such as significant underestimation of minimum values on an aggregated yearly time scale and restrictions of the parameter boundaries. Conversely, the copula models do not present such drawbacks but show feasible reproduction of key and operational statistics. We concluded that the periodic Markov chain based the copula models is a practicable method to simulate intermittent monthly streamflow time series.

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ON THE LIMIT SETS AND THE BASIC SETS OF CHAIN RECURRENT SETS

  • Koo, Ki-Shik
    • Journal of applied mathematics & informatics
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    • v.7 no.3
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    • pp.1029-1038
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    • 2000
  • In this paper, we show that if x is a positively Lyapunov stable point of an expansive homeomorphism with the pseudo-orbit-tracing-property, then x is a periodic point or its positive limit set consists of only one periodic orbit, and their periods are predictable. We give a necessary and sufficient condition that a basic set is to be a sink or source. Also, we consider some dynamical properties of basic sets.

Preparation of Periodic Mesoporous Organosilica/Polymer Composite (주기적인 메조포러스 유기실리카/고분자 복합재료 제조)

  • Dun, Li;Sur, Gil-Soo
    • Polymer(Korea)
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    • v.34 no.4
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    • pp.289-293
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    • 2010
  • Periodic mesoporous organosilicas (PMO) were synthesized using bis(triethoxy silyl) ethane (BTEE) as the precursor and dodecyl trimethyl ammonium bromide(DTMA), cetyl trimethyl ammonium bromide(CTMA), and octadecyl trimethyl ammonium bromide(ODTMA) as the templating agents. The surface area and pore volume of PMO decrease with the increasing of chain length of templating agents. However, the chain length of templating agents almost has no effect on the pore diameter of PMO. From the XRD and the DSC experiments, we found that the chain length of surfactants using as the templating agents has an effect on the melting transition of polyethylene. But it has no effect on the melting transition of poly(ethylene oxide). The results of TGA prove that the thermal decomposition temperature of polymer which was penetrated into PMO was increased.

A Study on the Fatigue Reliability of Structures by Markov Chain Model (Markov Chain Model을 이용한 구조물의 피로 신뢰성 해석에 관한 연구)

  • Y.S. Yang;J.H. Yoon
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.2
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    • pp.228-240
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    • 1991
  • Many experimental data of fatigue crack propagation show that the fatigue crack propagation process is stochastic. Therefore, the study on the crack propagation must be based on the probabilistic approach. In the present paper, fatigue crack propagation process is assumed to be a discrete Markov process and the method is developed, which can evaluate the reliability of the structural component by using Markov chain model(Unit step B-model) suggested by Bogdanoff. In this method, leak failure, plastic collapse and brittle fracture of the critical component are taken as failure modes, and the effects of initial crack distribution, periodic and non-periodic inspection on the probability of failure are considered. In this method, an equivalent load value for random loading such as wave load is used to facilitate the analysis. Finally some calculations are carried out in order to show the usefulness and the applicability of this method. And then some remarks on this method are mentioned.

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DYNAMICS OF AN IMPULSIVE FOOD CHAIN SYSTEM WITH A LOTKA-VOLTERRA FUNCTIONAL RESPONSE

  • Baek, Hun-Ki
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.12 no.3
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    • pp.139-151
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    • 2008
  • We investigate a three species food chain system with Lotka-Volterra type functional response and impulsive perturbations. We find a condition for the local stability of prey or predator free periodic solutions by applying the Floquet theory and the comparison theorems and show the boundedness of this system. Furthermore, we illustrate some examples.

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ON THE BIGTH OF PB-CHAINS FOR GENERAL AREA-PRESERVING MAPS

  • Kim, Yong-In
    • Communications of the Korean Mathematical Society
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    • v.9 no.4
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    • pp.857-872
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    • 1994
  • A PB-chain(Poincare-Birkhoff chain) is by definition a pair of elliptic and hyperbolic n-periodic orbits for a mapping and its existence has been well established numerically or analytically in many particular occasions such as in standard maps or twist maps [1, 8, 9] or Henon maps [1, 2, 12]. This paper gives focus on the investigaton of the appearance of such a PB-chain in a one-parameter family of general area-preserving maps and is in fact a generalization of the results given in [12] for a one-parameter family of specific area-preserving maps, so called Henon maps.

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