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result(s) for
"蒙特卡罗模拟"
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Can Flory-Stockmayer theory be applied to predict conventional free radical polymerization of multivinyl monomers? A study via Monte Carlo simulations
by
Jing Lyu;Yongsheng Gao;Zidan Zhang;Udo Greiser;Hongyun Tai;Wenxin Wang
in
Chemistry
,
Chemistry and Materials Science
,
Chemistry/Food Science
2018
The conventional free radical polymerization(FRP) of multivinyl monomers(MVMs) inevitably leads to gelation even at low monomer conversion resulting in difficulties to control and monitor the reaction process. Flory and Stockmayer(F-S theory)studied it based on two fundamental assumptions:(1) independent and equivalent vinyl groups;(2) no intramolecular cyclization.However, until now its applicability to FRP of MVMs(especially regarding the extent of intramolecular cyclization) is still controversial. In this paper, Monte Carlo simulations are used to study FRP of divinyl monomers by two kinetic models:with/without cyclization models. The results of the simulations are compared with the calculated gel points based on F-S theory and the experimental data. It is found that the intramolecular cyclization has a negligible impact on the polymerization process and the gel point before gelation, which are in agreement with the prediction by F-S theory, but the effect becomes significant above the gel points.
Journal Article
Fuzzy stochastic long-term model with consideration of uncertainties for deployment of distributed energy resources using interactive honey bee mating optimization
2014
This paper presents a novel modified interactive honey bee mating optimization (IHBMO) base fuzzy stochastic long-term approach for determining optimum location and size of distributed energy resources (DERs). The Monte Carlo simulation method is used to model the uncertainties associated with long-term load forecasting. A proper combination of several objectives is considered in the objective function. Reduction of loss and power purchased from the electricity market, loss reduction in peak load level and reduction in voltage deviation are considered simultaneously as the objective functions. First, these objectives are fuzzified and designed to be comparable with each other. Then, they are introduced into an IHBMO algorithm in order to obtain the solution which maximizes the value of integrated objective function. The output power of DERs is scheduled for each load level. An enhanced economic model is also proposed to justify investment on DER. An IEEE 30-bus radial distribution test system is used to illustrate the effectiveness of the proposed method.
Journal Article
Low-frequency E-field Detection Array(LFEDA)—Construction and preliminary results
by
SHI DongDong ZHENG Dong ZHANG Yang ZHANG YiJun HUANG ZhiGang LU WeiTao CHEN ShaoDong YAN Xu
in
中国气象科学研究院
,
人工触发闪电
,
低频电场
2017
In recent years, locating total lightning at the VLF/LF band has become one of the most important directions in lightning detection. The Low-frequency E-field Detection Array(LFEDA) consisting of nine fast antennas was developed by the Chinese Academy of Meteorological Sciences in Guangzhou between 2014 and 2015. This paper documents the composition of the LFEDA and a lightning-locating algorithm that applies to the low-frequency electric field radiated by lightning pulse discharge events(LPDEs). Theoretical simulation and objective assessment of the accuracy and detection efficiency of LFEDA have been done using Monte Carlo simulation and artificial triggered lightning experiment, respectively. The former results show that having a station in the network with a comparatively long baseline improves both the horizontal location accuracy in the direction perpendicular to the baseline and the vertical location accuracy along the baseline. The latter results show that detection efficiencies for triggered lightning flashes and return strokes are 100% and 95%, respectively. The average planar location error for return strokes of triggered lightning flashes is 102 m. By locating LPDEs in thunderstorms, we find that LPDEs are consistent with convective regions as indicated by strong reflectivity columns, and present a reasonable distribution in the vertical direction.In addition, the LFEDA can reveal an image of lightning development through mapping the channels of lightning. Based on three-dimensional locations, the vertical propagation speed of the preliminary breakdown and the changing trend of the leader's speed in an intra-cloud and a cloud-to-ground flash are investigated. The research results show that the LFEDA has the capability for three-dimensional location of lightning, which provides a new technique for researching lightning development characteristics and thunderstorm electricity.
Journal Article
The effect of poor compliance on the pharmacokinetics of carbamazepine and its epoxide metabolite using Monte Carlo simulation
by
Jun-jie DING Yun-jian ZHANG Zheng JIAO Yi WANG
in
Anticonvulsants - administration & dosage
,
Anticonvulsants - pharmacokinetics
,
Anticonvulsants - therapeutic use
2012
Aim: To study the effects of delayed and missed doses (poor compliance) on the pharmacokinetics of carbamazepine (CBZ) and its main active metabolite carbamazepine-10,11-epoxide (CBZE) in Chinese epilepsy patients using Monte Carlo simulation. Methods: CBZ and CBZE time-concentration profiles in various scenarios were generated based on a population pharmacokinetic study in Chinese epilepsy patients using Monte Carlo simulation. The scenarios included patients given multiple doses of CBZ that ranged from 100 to 300 mg three times daily or from 200 to 300 mg every 12 h. The therapeutic range of CBZ and CBZE for each scenario was estimated to assess the effect of delayed or missed doses and to design corresponding rescue regimens. Moreover, the impact of body weight, absorption rate and co-therapy with other antiepileptic drugs (phenytoin, phenobarbital and valproic acid) on the dosage recommendation was investigated in the event of poor compliance. Results: The risk for a sub-therapeutic range of CBZ and CBZE was increased in a dose-dependent manner in both two and three times daily regimens when delayed or missed doses occurred. The effects of poor compliance was less prominent on the lower daily doses compared with those on the higher daily doses. The dose recommendations, in the event of poor compliance, were time related and dose dependent. Patient body weight, absorption rate and co-therapy with phenytoin, phenobarbital and valproic acid had no significant impact on the dose recommendation. Conclusion; Patients with epilepsy should take the delayed doses as soon as they remember, and partial missed doses may need to be taken near or at the next scheduled time.
Journal Article
The geometric factor of high energy protons detector on FY-3 satellite
by
ZHANG ShenYi ZHANG XianGuo WANG ChuiQin SHEN GuoHong JIN Tao ZHANG BinQuan SUN YueQiang ZHU GuangWu LIANG JinBao ZHANG XiaoXin LI JiaWei HUANG Cong HAN Ying
in
Artificial satellites
,
Astrophysics
,
Channels
2014
Geometric factor is the key parameter for inversion of particle spectrum in space particle detection. Traditional geometric factor is obtained through the method of numerical calculation with the actual structure of the detector as the input condition. The degree of accuracy for data inversion is reduced since traditional geometric factor fails to take into account the physical process of interaction between the particle and substance as well as the influence of factors such as the particle interference between different energy channels on the measurement result. Here we propose an improved geometrical factor calculation method, the concept of which is to conduct actual structural modelling of the detector in the GEANT4 program, consider the process of interaction between the particle and substance, obtain the response function of the detector to particles of different energy channels through the method of Monte Carlo simulation, calculate the influence of contaminated particle on the geometrical factor, and finally get the geometrical factors for different energy channels of the detector. The imrpoved geometrical factor obtained through the method has carried out inversion for the data of high energy protons detector on China's FY-3 satellite, the energy spectrum after which is more in line with the power law distribution recognized by space physics. The comparison with the measured result of POES satellite indicates that the FY-3 satellite data are in good accordance with the satellite data, which shows the method may effectively improve the quality of data inversion.
Journal Article
Optimization design of GaN betavoltaic microbattery
2012
Betavoltaic radioisotope microbatteries have gradually become the research direction of micro-power sources because of their several advantages, including small scale, stable output performance, long service life, high energy density, strong anti-jamming capability, and so on. Based on the theory of semiconductor physics, the current paper presented a design scheme of isotope microbattery with wide-gap semiconductor material GaN and isotope 147Pm. In consideration of the isotope’s self-absorption effect, the current paper studied and analyzed the optimization thickness of semiconductor and isotope source, junction depth, depletion region thickness, doping concentration, and the generation and collection of electron hole pairs with simulation of transport process of beta particles in semiconductor material using Monte Carlo simulation program MCNP. In the proposed design scheme, for a single decay, an average energy of 28.2 keV was deposited in the GaN, and the short circuit current density, open circuit voltage, and efficiency of a single device were 1.636 μA/cm2, 3.16 V, and 13.4%, respectively.
Journal Article
Flip-flops soft error rate evaluation approach considering internal single-event transient
The internal single-event transient (SET) induced upset in flip-flops is becoming significant with the increase of the operating frequency. However, the conventional soft error rate (SER) evaluation approach could only produce an approximate upset prediction result caused by the internal SET. In this paper, we propose an improved SER evaluation approach based on Monte Carlo simulation. A novel SET-based upset model is implemented in the proposed evaluation approach to accurately predict upsets caused by the internal SET. A test chip was fabricated in a commercial 65 nm bulk process to validate the accuracy of the improved SER evaluation approach. The predicted single-event upset cross-sections are consistent with the experimental data.
Journal Article
Distribution Patterns of Medicinal Plants along an Elevational Gradient in Central Himalaya, Nepal
by
Maan B. ROKAYA Zuzana MUNZBERGOVA Mani R. SHRESTHA Binu TIMSINA
in
Altitude
,
Dispersal
,
Distribution patterns
2012
This study aimed to compare the distribution patterns and trends of plant parts used among different groups of medicinal plants, geographical regions,and between medicinal plants and all vascular plants.We used the published sources for elevation records of 2,331 medicinal plant species to interpolate presence between minimum and maximum elevations and estimated medicinal plant richness for each 100-m elevational band. Monte Carlo simulations were used to test whether differences in elevational distribution between different groups of medicinal plants were significant. Total number of medicinal plants as well as different groups showed unimodal relationship with elevation. The elevational distributions of medicinal plants significantly differ between regions and between medicinal plant groups.When comparing the richness of all medicinal plants to all vascular plants,Monte Carlo simulations indicated that the numbers of medicinal plants are higher than expected at low elevations.The highest richness of medicinal plants at low elevation could be possibly due to favorable environmental factors such as high temperature, rainfall,sunlight or due to higher density of human population and thus higher pressure on use of any plants in lower elevations.
Journal Article
Reliability analysis of supporting pressure in tunnels based on three-dimensional failure mechanism
2016
Based on nonlinear failure criterion, a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory. Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem. It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass. The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism. Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure. The reliability indexes calculated by two methods are in good agreement. Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed. It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter, and that small changes occurring in the coefficient of variation would make great influence of reliability index. Thus, significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.
Journal Article
Estimation of Partially Specified Spatial Panel Data Models with Random-Effects
by
Yuan Qing ZHANG Guang Ren YANG
in
Asymptotic methods
,
Asymptotic properties
,
Computer simulation
2015
In this article, we study estimation of a partially specified spatial panel data linear regression with random-effects. Under the conditions of exogenous spatial weighting matrix and exogenous regressors, we give an instrumental variable estimation. Under certain sufficient assumptions, we show that the proposed estimator for the finite dimensional parameter is root-N consistent and asymptotically normally distributed and the proposed estimator for the unknown function is consistent and asymptotically distributed. Consistent estimators for the asymptotic variance-covariance matrices of both the parametric and unknown components are provided. The Monte Carlo simulation results verify our theory and suggest that the approach has some practical value.
Journal Article