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Stochastic particle based models for suspended particle movement in surface flows

International Journal of Sediment Research 2014年第2期29卷 195-207页

作者： Christina W.TSAI Chuanjian MAN jungsun oh Department of Civil Structural and Environmental EngineeringState University of New York at BuffaloBuffaloNY 14051USA Assoc.Prof. Department of Civil and Environmental Engineering National Taiwan University

Modeling of suspended sediment particle movement in surface water can be achieved by stochastic particle tracking model *** this paper,different mathematical forms of particle tracking models are introduced to describe particle movement under various flow conditions,i.e.,the stochastic diffusion process,stochastic jump process,and stochastic jump diffusion *** the stochastic diffusion process can be used to represent the stochastic movement of suspended particles in turbulent flows,the stochastic jump and the stochastic jump diffusion processes can be used to describe suspended particle movement in the occurrences of a sequence of extreme *** extreme flow herein is defined as a hydrologic flow event or a hydrodynamic flow phenomenon with a low probability of occurrence and a high impact on its ambient flow *** this paper,the suspended sediment particle is assumed to immediately follow the extreme flows in the jump process(*** time lag between the flow particle and the sediment particle in extreme flows is considered negligible).In the proposed particle tracking models,a random term mainly caused by fluid eddy motions is modeled as a Wiener process,while the random occurrences of a sequence of extreme flows can be modeled as a Poisson *** frequency of occurrence of the extreme flows in the proposed particle tracking model can be explicitly accounted for by the Poisson process when evaluating particle *** ensemble mean and variance of particle trajectory can be obtained from the proposed stochastic models via *** ensemble mean and variance of particle velocity are verified with available *** of the proposed stochastic particle tracking models for sediment transport modeling is also discussed.

关键词： Suspended sediment Particle tracking model Stochastic modeling Diffusion process Poisson jump process Jump diffusion process Extreme flows

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Stochastic structural optimization using particle swarm optimization, surrogate models and Bayesian statistics

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Chinese Journal of Aeronautics 2013年第1期26卷 112-121页

作者： Jongbin Im jungsun Park Korea Aerospace Research Institute Department of Aerospace and Mechanical Engineering Korea Aerospace University

This paper focuses on a method to solve structural optimization problems using particle swarm optimization （PSO）, surrogate models and Bayesian statistics. PSO is a random/stochastic search algorithm designed to find the global optimum. However, PSO needs many evaluations compared to gradient-based optimization. This means PSO increases the analysis costs of structural optimization. One of the methods to reduce computing costs in stochastic optimization is to use approximation techniques. In this work, surrogate models are used, including the response surface method （RSM） and Kriging. When surrogate models are used, there are some errors between exact values and approximated values. These errors decrease the reliability of the optimum values and discard the realistic approximation of using surrogate models. In this paper, Bayesian statistics is used to obtain more reliable results. To verify and confirm the efficiency of the proposed method using surrogate models and Bayesian statistics for stochastic structural optimization, two numerical examples are optimized, and the optimization of a hub sleeve is demonstrated as a practical problem.

关键词： Bayesian statistics Kriging Particle swarm optimization (PSO) Response surface method (RSM)

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IMAGING OF ADENOVIRUS-MEDIATED GENE TRANSFER OF HUMAN SODIUM IODIDE SYMPORTER BY TC-99M PERTECHNETATE SCINTIGRAPHY IN MICE

IMAGING OF ADENOVIRUS-MEDIATED GENE TRANSFER OF HUMAN SODIUM...

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首届中日韩核医学会议

作者： Won Woo Lee Dae Hyuk Moon So Yeon Park jungsun Jin Sung Jin Kim Heuiran Lee Departments of Nuclear Medicine Asan Medical Center University of Ulsan College of MedicineSeoulKorea Departments of Nuclear Medicine Asan Medical Center University of Ulsan College of MedicineSeoulKorea Departments of Microbiology Asan Medical Center University of Ulsan College of MedicineSeoulKorea Departments of Microbiology Asan Medical Center University of Ulsan College of MedicineSeoulKorea Departments of Microbiology Asan Medical Center University of Ulsan College of MedicineSeoulKorea Departments of Microbiology Asan Medical Center University of Ulsan College of MedicineSeoulKorea

＜正＞Objectives: Human sodium iodide symporter （hNIS） is naturally present in the plasma membrane of human thyroid cells, which mediates the active transport of iodide. The aim of this study was to explore the possibility of imaging the adenovirus-mediated gene transfer of hNIS by Tc-99m pertechnetate （TcO4） scintigraphy in mice. Methods: Replication-defective recombinant adenovirus was prepared, which encoded either hNIS （Rad-hNIS） or LacZ （Rad-LacZ） gene expression cassette. hNIS gene expression was examined by western blotting in hNIS defective thyroid cancer cell line （FRO） infected with Rad-hNIS 48hr post-infection. The uptake of TcO4 was then evaluated by adding the tracer to culture media. To monitor hNIS expression in vivo, 9 to 12wk-old balb/c mice were injected with Tris buffer only, 2x108, 1x109 infectious particles （IP） of Rad-hNIS, or 1x109 IP of Rad-LacZ via tail vein （n=5-7 for each group）. Forty-eight hrs later, 3.7 MBq of TcO4 was injected intraperitoneally and whole body images were obtained for 1 hr. Then, mice were sacrificed for the biodistribution of TcO4 and the measurement of hNIS mRNA by RT-PCR. Results: hNIS protein was readily detected in the FRO cells infected with Rad-hNIS at 10 MOI. TcO4 uptake increased gradually as the cells were infected with increasing Rad-hNIS （96.5±51.4, 266.9±91.3, and 558.6±160.7-fold increase at MOI 5, 20, 100, respectively）. Sodium perchlorate inhibited the uptake completely. Scintigraphic and biodistribution studies clearly revealed high hepatic uptake of TcO4 （22.7□11.2 % injected dose/g） in mice injected with 1x109 IP of Rad-hNIS, which was significantly higher （p ＜ 0.01） than that in mice injected with Tris buffer （7.4 □0.5）, 2x108 IP of Rad-hNIS （8.5 □2.7）, or 1x109 IP of Rad-LacZ （5.8 □0.8）. Co-administration of sodium perchlorate inhibited the hepatic uptake of TcO4. hNIS mRNA was exclusively detected in the liver of Rad-hNIS groups, with much higher intensity in 1x109 Rad-hNIS group. Two mice injected wi

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