Papers by Keyword: Monte-Carlo Simulation

Abstract: A procedure to calculate the transient response of optimal controlled stochastic Van Der Pol oscillator is proposed. The stochastic averaging method is employed to obtain a partially averaged Itô equation for the amplitude process. The dynamical programming equation is adopted to minimize the system response. An optimal control law with a control constraint is established. The completed averaged Itô equation is obtained. The transient probability density function is solved from Fokker-Planck-Kolmogorov equation by Galerkin method. Results obtained show the proposed method is accurate. The effective of the control strategy is significant.

Abstract: A statistics method was carried out to characterize the fatigue strength distribution of GF/PP composites. Based on the stress of yarn bundles, the Weibull distribution parameters were determined. Also, we had presented an expression of interfacial shear stress between yarn tows and matrix. A Monte-Carlo simulation with 2D shear-lag equation had been used to analyze the tensile strength and simulate the failure process of unidirectional stretch of composites. Good agreements were obtained between the predicted results and experimental data.

Abstract: The CAN bus scheduling performance can be very important for the design of CAN bus system, it is related to the normal operation of the bus system. The CAN bus scheduling performance is studied and calculated using the classical first order second moment method based on EDF scheduling method; an example of the bus system scheduled by EDF method is used to calculate the stability by this method. MONTE-CARLO simulation is imitated using software programming; by comparing the results above the formula proves correct.

Abstract: Chloride ingress is a major factor affecting durability of reinforced concrete structures. In the present study, service life of a RC flexural member in chloride environments is predicted. First, model for service life is established considering model error and the coupling effects of loading condition and environmental factors on the chloride penetration. Then, service life is predicted in probabilistic framework of Monte Carlo simulation. The results show that the use of a lognormal distribution for the service life seems relevant; the service life shows a great scatterings.

Abstract: Precise determination of diffraction peak positions is of particular importance for the evaluation of residual strains. Neutrons are commonly used to probe residual strains from material volumes in depths of several millimetres under the sample surface. However, neutron strain analyses are critical for the near surface region. When scanning close to a sample surface, aberration peak shifts arise, which can be of the same order as the peak shifts related to residual strains [1]. Series of Monte Carlo (M.C.) simulations using the software package RESTRAX/SIMRES [2] were carried out to simulate the peak shift as a function of gauge volume depth, monochromator curvature and other instrumental parameters, which can be used to quickly optimise the experimental setup for direct measuring residual strains near the sample surface at an arbitrary surface orientation. The M.C. simulations were compared and agree very well with the experimental data, not only for a stress free steel sample but as well for a deep rolled steel sample, measured at the STRESS-SPEC diffractometer at the research reactor FRM II, Garching (Germany).

Abstract: It is convenient and effective to use Monte Carlo simulation (MCS) technique in project schedule risk analysis and assessment, but at the same time, the indexes put forward by scholars up to now is quite few, leaving construction schedule risk assessment still difficult to carry out. Therefore, based on PERT network assumption, the shortcomings of current project schedule risk indexes are summarized and new project schedule risk index is put forward to estimate the criticality of each activity and path to provide more information for project schedule controllers. In the case studied, with the application of the new index, the critical index of each activity is given and divided into five levels, and the new index put forward in this paper shows great superiority over the classic indexes.

Abstract: This work studies the temperature-driven ferroelectric phase transition of ferroelectric polarization under the absence of electric field. The modified Heisenberg model in three dimensions was considered and simulated via Monte Carlo simulation. The Metropolis algorithm and the periodic boundary condition were employed. The dependence of electric polarization on temperature was investigated to define the ferroelectric phases and their structural phase transitions. From the results, with well-defined set of relevant temperature parameters, the phase dependent polarization-behavior was found with a sudden change in its behaviors at the transition points. The structure factors were also considered and supported these phase changes. This conclusively pinpointed the important of temperature-dependent parameters in modeling ferroelectric materials.

Abstract: This work used Monte Carlo simulation to investigate the effect of lattice strain on critical temperature of the ferromagnetic Ising ultra-thin-film. Using Bethe-Slater interpretation, exchange interaction was assumed Lennard-Jones (LJ) potential function, and becomes functions of interatomic distance. The cluster flip algorithm was used to update the spin configuration, where energy and magnetization were measure to extract critical temperature via the fourth order cumulant of the magnetization. Results show that initial interatomic distance and strain have strong effect on magnetic critical point behavior. The critical point can be enhanced or suppressed depending on how exchange interaction is modified by the values of initial interatomic distance and strain. A scaling function in predicting critical temperatures is also given in this work. Results agree well with previous applicable works, which confirms the reliability of the reported results.

Abstract: The true trajectory of spacecraft disperses from the nominal due to kinds of errors and perturbations, including environment, actuator and sensor uncertainties. This paper studies the error analysis problem of closed-loop control for spacecraft orbital transfer via Monte Carlo method. At first, errors that affect the true state are introduced and a navigation-target-correction loop system for Monte Carlo simulation is built. A dynamical model for orbital transfer is established, based on which both the extended Kalman filter (EKF) algorithm and correction maneuver control algorithm are developed. Precision analysis is studied of high eccentric orbital (HEO) transfer under open-loop and closed-loop control respectively. The simulation results prove the validity of the proposed method.

Abstract: Water distribution systems (WDS) are important urban infrastructures which are designed for safely conveying potable water from treatment plant to users tap with adequate quantity and desired quality. The water quality reliability evaluation of WDS has positive and critical meanings for ensuring water supply security, reliability and maintaining a high level of service. In this paper, firstly the evaluation index of water quality reliability of municipal water distribution systems has been set up which is characterized by the residual chlorine availability. Then, taking into account the random nature of component failures, the variation of water demand through the 24 hours of a day and the chlorine variation of the treated water in water plant through the 24 hours of a day, the Monte Carlo-based reliability model are established based on the dynamic link library toolkit provided by EPANET 2.0 for the hydraulic and water quality calculation engine. Finally, the water quality reliability of each node and system is evaluated taking water network of some region in Tianjin Binhai High-tech Area (BHA) as example. The research results can be applied to the whole process from planning and design to operation of WDS, and the theoretical basis and decision support for optimal design and operation of WDS are provided for designers and decision-makers.