Monte Carlo Numerical Simulation Method Research Articles

The Return Period Wind Speed Prediction of Beijing Urban Area Based on Short-Term Measured Wind Speed

To predict and explore the return period wind speed distribution in Beijing urban area, based on the short-term measured wind speed record, the measured independent storm peak samples are extracted and the Monte–Carlo numerical simulation method is used to randomly generate pseudo-independent storm peak samples with the same distribution as the independent storm peak samples. In addition, the appropriate threshold is used to select and extract the over-threshold independent storm peak samples from the measured samples. And, then, the return period wind speed of the whole wind direction is predicted. Further, the traditional Cook method is used to predict and analyze the return period wind speed of each wind direction according to the measured wind speed data. The results show that the return period wind speed prediction results of the whole wind direction corresponding to the simulated pseudo samples and the measured over-threshold samples are basically close to each other, and the maximum relative deviation is less than 7%. The mean relative deviation of the return period wind speed prediction results is about 10.6% between each wind direction and the whole wind direction, and the mean relative deviation is about 9.4% between the RPWS prediction result of each wind direction and the design value of the code. In addition, the return period wind speed prediction values of the west by southwest, northwest and north by northeast wind directions exceed the design value of the code, while the predicted values of the other wind directions are within the envelope range of the design value of the code. Finally, the research content of this paper can provide some reference for the wind resistance design analysis of building structures in Beijing area.

Coupled Parametric Vibration Model and Response Analysis of Single Beam and Double Cable Under Deterministic Harmonic and Random Excitation

In order to reveal the coupling parametric vibration characteristics of stay cables under combined excitation, considering the effects of cable geometric nonlinearity, inclination and the cooperative vibration of adjacent cables and bridge deck beams, a single-beam–double-cable coupled parametric vibration model excited by Gaussian white noise and deterministic harmonic excitation is established, and the coupled motion equations are derived. The Milstein–Platen method is used to directly obtain the coupled random vibration time history of the single-beam–double-cable structure, and an iterative method is proposed to counter the influence of the parametric diffusion coefficient on the numerical format. By comparing with the finite element method and the Monte Carlo numerical simulation method, the accuracy of the Milstein–Platen method in solving the vibration time history of cable–beam coupling parameters under combined excitation is first verified. Then the random displacement, power spectral density and probability density variation of the cable and beam under the combined excitation of different intensities are analyzed from the angle of random orbit. The results show that under the joint action of deterministic harmonics and random excitation, the time–domain, frequency, and probability characteristics of the single-beam–double-cable coupling system are greatly affected by the Gaussian white noise excitation proportion coefficient, and the degree of influence is different. In addition, compared with the single cable model, the vibration analysis results of the coupling model considering multiple stay cables are more reasonable.

Simulation of radiative transfer in gas-liquid foams

The results of the radiation light transfer in the gas-liquid foams are presented. To study the probing light transfer in gas-liquid foam-like media at different stages of aging, a Monte Carlo numerical simulation method is proposed. To take into account the re-reflections at the phase interfaces, the approach based on the Fresnel formula is applied. Kelvin cells structures are considered as a model medium, imitating gas bubbles in a liquid matrix during aging (coarsening), which represents the transition of a foam-like medium from “wet” to “dry”. Such transition is caused by the slow liquid flow along the gas cells walls and Plateau-Gibbs channels due to the influence of the gravitational force in an isolated system. During the evolution process, the volume fraction of the liquid phase decreases and the average size of the gas cells of the foam-like medium increases. The three-dimensional cellular structure at different evolution stages is represented as a system of close-packed ordered spheres or tetradecahedrons of various geometric sizes depending on the aging process duration. The Monte Carlo modeling of the radiation light transfer in scattering two-phase foam-like media, taking into account the redistribution at the interfaces of two phases by use of Fresnel formulas at different coursing stages, is presented. The transmittance and backscattering coefficients of a probing light are obtained using the Monte Carlo numerical simulations and Fresnel formulas for the gas-liquid foams. The obtained results are well correlated with the spectrometric measurements of the foamed liquid produced by Gillete (Gillete shaving cream). The influence of the anisotropy factor on the optical length of the probing light was carried out. The development of the theoretical approaches to the diagnostics of the two-phase foam-like materials makes it possible to synthesize foamed materials with established rheological and structural properties to increase and improve the efficiency of evaluating of the functional characteristics for such materials.

Research on Evolutionary Game Analysis of Spatial Cooperation for Social Governance of Basin Water Pollution

Given that the two institutional arrangements of government regulation and market allocation cannot effectively solve the conflict between individual and collective interests in the process of water pollution control, this work presents a useful attempt on the third institutional arrangement of environmental governance—social governance—to overcome the dilemma. Based on common pool resource theory and multi-person prisoner game analysis framework, it incorporates environmental damage function, spatial network structure, and strategy update based on a learning mechanism into the analysis framework. In addition, it constructs a set of spatial cooperative evolution game models of basin water pollution social governance, so as to test the guarantee effect of the spontaneous collective action conditions of basin polluters on the long-term survival of the new system. This work adopts the Monte Carlo numerical simulation method to conduct the simulation experiment research. The experimental results show it is possible to successfully form collective actions entirely dependent on emitters, which yet requires a large initial scale of cooperation, that is, a majority of the emitter group autonomously abides by credible commitments. In this process, transparent full information and active organizational mobilization have a positive effect on the collective action development. The organic combination can better guide emitters to abide by credible commitments to achieve the optimal collective interests. The study results can provide a theoretical and practical reference for the social governance mechanism at a large-scale basin.

Study on the Effect of Two Uncertainty Parameters on Scramjet Engine Using Monte Carlo Simulation

Today, aerospace engines are developing rapidly, these engines are divided into two groups of gas turbines and without gas turbines. In this thesis, the thermodynamic performance of the scramjet engine is examined. This study is carried out with consideration of uncertainty parameters. Two parameters of the combustion chamber efficiency and heating value of fuel are considered as uncertainty parameters. Using Monte Carlo numerical simulation method, the functional curves of the scramjet engine were investigated, and Analysis is done. According to the use of uncertainty parameters, first, a brief explanation of the uncertainty illustrates according to calculate using their functions and the Monte Carlo method. Also, the uncertain effects on the functional charts are analyzed considering the variable taking into account each of the uncertainty parameters. According to the obtained results, it was determined that the uncertain effect of the combustion chamber is negligible compared to the heating value of the fuel, the number of different points of 100,200 and 300 is similar to each other, and according to the extracted functional charts With regard to the uncertainties, it was observed that the least compression efficiency and special fuel consumption would have the greatest effect from the uncertainties.

Analysis of polarization characteristics of backscattered light and reflected light of underwater active light source

The analysis of the polarization characteristics of reflected light and backscattered light can provide theoretical support for the research on key technologies of underwater active light source polarization imaging. The influence of the parameters of different light sources, environments, and reflective targets on the characteristics of the reflected light was analyzed. The difference in the degree of polarization between the reflected light and the backscattered light was also determined. A Monte Carlo numerical simulation method based on a combination of Mie scattering theory and polarimetric bidirectional reflectance distribution function was used to establish underwater photon scattering and reflection-tracking models. Through simulation and analysis of the influence of the underwater environment system on the polarization characteristics of the backscattered photons and the reflected photons of different polarization types of the incident light, the following conclusions are drawn. First, in the same condition, the difference in polarization characteristics of backscattered and reflected light of circularly polarized light was larger than linearly polarized light. This is due to the better polarization-maintaining ability of circularly polarized light than linearly polarized light. Second, when various types of materials were used as reflective targets, the difference in their complex refractive indices changed the polarization of the reflected photons. And the complex refractive index had varying effects on the two types of polarized light.

On the possibility of indirect measurement of the thin carbon films thickness using energy-dispersive analysis

The article describes theoretical feasibility of a technique for indirect measurement of the thin carbon films thickness using energy dispersive x-ray spectroscopy. The method is based on measuring the ratio of the characteristic radiation from the substrate material below the analyzed carbon film and from the material of the additional covering layer. The technique was compared with a well-known method based on measuring the characteristic substrate material radiation. The possibilities and limits of applicability of the energy dispersive spectroscopy for the thickness determination of thin carbon films were qualitatively determined by Monte Carlo numerical simulation method of characteristic x-ray spectra.

A Bistatic Analytical Approximation Model for Doppler Rate Estimation Error from Real-Time Spaceborne SAR Onboard Orbit Determination Data

Real-time spaceborne bistatic SAR imaging could significantly reduce the whole processing time and can enhance the spaceborne SAR mission availability. Onboard real-time SAR imaging relies on the Doppler parameters estimated from the real-time onboard orbit determination system (OODS) measurement, whose accuracy level is not comparable to the orbit ephemeris data in ground-based SAR processing. The investigation of the impact of error in real-time OODS measurements on bistatic SAR image quality is necessary, and it can help to clarify the key parameter limits of the real-time OODS. The monostatic analytical approximation model (MonoAAM) for spaceborne SAR reduces simulation complexity and processing time compared to the widely used numerical simulation method. However, due to the different configurations between spaceborne bistatic and monostatic SAR, simply applying the MonoAAM on spaceborne bistatic SAR cannot guarantee the desired result. A bistatic analytical approximation model (BiAAM) for Doppler rate estimation error from real-time OODS measurement in real-time spaceborne bistatic SAR imaging is proposed for characterizing the estimation error. Selecting quadratic phase error (QPE) as an evaluation variable, the proposed BiAAM model can provide QPE estimation results for each position of the satellite in its orbit and the maximum QPE estimation for the whole orbit, while revealing the different process of OODS measurement error transferring to QPE in spaceborne bistatic SAR. The correctness and reliability of BiAAM are evaluated by comparing the result with a Monte Carlo numerical simulation method. With the supporting result from BiAAM, the concept and early-stage development of a real-time onboard bistatic SAR imaging mission could be possibly benefited.

Statistical Linearization Method for the Piecewise Nonlinear Systems

The Monte-Carlo numerical simulation method is applied to obtain the approximate probability distributions of the response of the piecewise nonlinear systems to random excitation. The expression of the equivalent linearization parameters for the piecewise nonlinear system is derived by the proposed statistical linearization method. To illustrate the accuracy of the linearization method, the present paper has compared the statistical characteristic value obtained by both the Monte Carlo numerical simulation method and the Statistical linearization method, while the time history analysis also shows a good agreement. Linearization of piecewise stiffness nonlinear model is displayed.

Cyclic virtual test on wood furniture by Monte Carlo simulation: from compression behavior to connection modeling

Prediction of durability of wood product is a major challenge and an important goal for furniture industry. Numerical simulation based on approximation methods such as the finite element method (FEM) is an efficient and powerful tool to address this challenge while avoiding expensive experimental testing campaigns. Nevertheless, the strong heterogeneity of wood-based materials, the specific geometrical characteristics of wood-based structures (such as furniture that can often be represented as an assembly of beams, plates and/or shells) and the complex nonlinear 3D local behavior near the connections between structural parts may induce some difficulties in the numerical modeling and virtual testing of furniture for robust design purposes. Especially, when cyclic loading occurs, the behavior of junctions in furniture involves a local permanent strain that increases with the number of cycles and that can lead to an important gap potentially affecting the structural integrity of furniture. In this paper, we present an experimental campaign of cyclic compression tests carried out on spruce specimens. Theses specimens are cut out from a bunk bed and loaded under cyclic compression. The cyclic compression loading applied to the specimens leads to an evolution of the permanent strain during cycles that is modeled using a simple law describing the displacement gap as a function of the number of cycles. Considering the strong dispersion in the mechanical properties of wood-based materials and the variabilities induced by the experimental configuration, a stochastic modeling of the gap is proposed by having recourse to the maximum entropy (MaxEnt) principle in order to take into account the random uncertainties on the experimental setup and between the test specimens. The random mechanical response of a complex corner junction in a bunk bed under cyclic loading is then numerically simulated by using a Monte Carlo numerical simulation method as stochastic solver. This provides independent realizations of the random gap evolution (with respect to the number of cycles) in the bunk bed corner, allowing probabilistic quantities of interest related to the random gap, such as first- and second-order statistical moments (mean value, standard deviation) as well as confidence regions (with a given probability level), to be estimated.

Determining age of high-explosive to support nuclear warhead dismantlement verification

The future international nuclear disarmament may involve the dismantlement of nuclear warheads. After the dismantlement of a nuclear warhead, the separated explosive needs authentication that it comes from the dismantled nuclear warhead. In this paper, the Monte Carlo numerical simulation method was used to study the feasibility and result of determining the source of the explosive by analyzing the nuclide abundances of the explosive and determining the age of the explosive (calculated since the explosive was placed in the nuclear warhead). First, the JMCT software was used to analyze the nuclei produced by the neutron reactions in the explosive of the nuclear warhead. As a result, it was found that 14C is the most promising to be used to determine the source of the explosive. Second, the relationships between the average abundance of 14C and the age of the explosive, the spatial distribution of the 14C abundance in the explosive were calculated by using the JMCT software. Finally, it is found that, compared to the WgPu warheads (nuclear warheads with weapons-grade plutonium cores), the 14C abundances of the explosives of the WgU warheads (nuclear warheads with weapons-grade uranium cores) are much lower (the ages of the explosives are the same), and it is more difficult to measure the latter; for the WgPu warheads with the structures based on Model 3 and Model 4 (the warhead models employed were proposed by Steve Fetter), it can be determined that whether the separated explosives come from the dismantled nuclear warheads or are common ones (or the fake ones prepared by the verified party) after the dismantlement of the nuclear warheads by measuring the 14C abundances in the explosives (including the average abundances and the spatial distributions of the abundances) and determining the ages of the explosives, which realizes the source authentication of the explosives.

A method for evaluating gas saturation with pulsed neutron logging in cased holes

Tight gas reservoirs have been one of the most important field of gas exploration and development, and the dynamic monitoring of gas saturation is of great significance to the adjustment of oilfield development scheme. Pulsed neutron logging technology plays an important role in the evaluation of gas saturation in cased holes. The low porosity of tight gas reservoir presents a new challenge to the application of pulsed neutron logging technology. In order to further investigate the measurement information of pulsed neutron logs to improve the performance of gas saturation measurement, the Monte Carlo numerical simulation method is used to study the gas saturation responses of different parameters obtained by the pulsed neutron-gamma logging instrument with an extra gamma-ray detector added. The results show that the capture count ratio measured by the instrument is mainly affected by changes in the hydrogen index of the formation. The ratio of pure inelastic gamma rays is more sensitive to the variation of formation density. When the porosity of the reservoir is fixed, the gas layer has a low hydrogen index and low density relative to the water layer. By combining the response characteristics of the two ratios, a new gas saturation evaluation parameter (GSEP) is proposed to evaluate gas saturation. The new method displays a higher gas sensitivity compared with the conventional ratio method and macroscopic capture cross section (Sigma) method. In addition, the response characteristics of GSEP in different well logging environments are also studied. It displays GSEP is less affected by the variation of the formation water salinity and clay contents compared with the Sigma method. At last, field examples are presented to validate the effectiveness of the proposed method.

Structure Earthquake Demand Importance Analysis Based on Variance Importance Analysis

Under the action of Taft ground motion records, the dynamic nonlinear time history analysis of the reinforced concrete frame structure were carried out. The earthquake demands of the reinforced concrete frame structure were given, the importance index of each random variable was obtained by variance importance analysis method of this reinforced concrete frame structure which was solved by Monte Carlo numerical simulation method. The results show that: The importance sorting of random variables, such as yield strength, damping ratio and structural quality was ahead and elasticity modulus of concrete was in the end for most earthquake demands. When analyzing the earthquake demand of reinforced concrete frame structure, we can consider the influence of several random variables, such as the yield strength of steel bar, the damping ratio and the structural quality. The calculation and analysis above may be helpful for improving the calculation efficiency of the analysis of earthquake demands.

Prediction of arrival flow profile of transit stream on link

Abstract It is essential in coordinated control to analyses the relationship of vehicular stream between upstream and downstream on arterial, and the arrival flow profile of section is a useful tool to describe the relationship. The arrival flow profile of transit stream is variable because of lower speed and stopping service. The objective of this paper is analyzing the relationship and characteristic of the transit stream, and predicting the arrival flow profile of transit stream on link. According the road conditions, some critical sections on arterial were defined. Simulation detected data were collected, the arriving vehicles at different signal periods were summarized and counted according to the smaller intervals, and the arrival flow profiles on critical sections were drawn. The impact of arrival flow profile by segment dispersion and stopping service was analyzed. On the basis of the speed cumulative probability distribution, transfer matrix which considers segment dispersion was built. The postpone time of transit vehicle was computed with Monte Carlo numerical simulation method. On the basis of postpone time cumulative frequency curve, postpone transition rate of interval was obtained by shifting the curve and calculating the areas, and the transfer matrix which considers stopping service was built. The arrival flow rate of upstream section multiplied by the transfer matrix made the arrival flow rate of downstream section on link. The results show that Monte Carlo numerical simulation method is feasible, and the relative error of predicted distribution of arrival flow rate is small. The prediction methods of arrival flow rate based on transfer matrix is effective.

The Improvement of the Design Standard of Overloaded Highway

With the development of the transportation industry, the trend of overload is obviously, design load of highway bridges needs to be improved. Based on the field investigation and data analysis, this study modifies the design standers of highway. The regularities on characteristics of models, vehicle weight and the distribution of axle load and spacing were studied. Using the Matlab programming language and the Monte Carlo numerical simulation method to simulate a random traffic model, then loaded on simple bridges and continuous bridges with different span in order to calculate bending effect. The data were compared with the first level in highway load code and proposed the load increase parameters: when the span is less than 20 m, then use 1.2 times the standard specification in bridge design; in other situation, use 1.3 times the standard factor. Analyzing the characteristic of the vehicle load, can not only give technical parameters for the quantitative analysis of overloading traffic effects on the fatigue damage of bridge, but also provide a reference for bridge design units and the operation management department. So it has great realistic significance and research value.

The Method for Estimating the Time to Failure in Accelerated Life Test

Accelerated life test was an important means to obtain storage reliability index of missile-borne photoelectric system. Because of difficulty to continuously test, the number of failure samples in the test range could be only got. Whether distribution intervals, logarithmic distribution or new failure time estimation method proposed in this paper such as range median distribution and the uniform distribution of the index had their applicable limitations. On the basis of comparison to Monte Carlo numerical simulation method, the characteristics of the applicability of the estimation method based on Weibull distribution were explored.

Applications of the Phase Transition Theory in Visual Recognition and Classifications

Total discrimination is a measure of information defined by Kullback. It has been shown that total discrimination is useful in measurements of performance and optimization of classifications in visual recognition. Using the Monte Carlo numerical simulation method, we studied some of these behaviors in a system of data, which were generated from visual diagnoses of cell preparations in medicine, of different sample sizes N. The processes categorize cell abnormalities into m classes. Our study suggests that there is a "data structural change" or possibly a "phase transition" in the data system, as the number of classes m in the classification changes through the previously identified optimal classification number m C. We found that the total discrimination peaked at m C and seemed to diverge at the optimization point as N → ∞, based on finite-size scaling analysis technique from the phase transition theory. Using the finite-size analysis method, we calculated the "thermal" exponent v for the data system and the "critical" exponent φ for total discrimination, and the calculation gave v = 3.33 ± 1.00 and φ = 0.40 ± 0.10. An order parameter 〈 n〉 which differentiated an "ordered" phase (below m C) from a "disordered" phase (above m C ) was also defined. The behaviors of 〈 n〉 near m C supports the hypothesis that there is a possible "phase transition" of the system taking place. Therefore, m C is both an optimization point in visual classification and a "critical point" in the context of the theory of phase transition. The connection of these two will not only provide the theoretical basis in the optimization in visual classification, but also widen the applications of the theory of phase transitions.