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Application and Optimization of Monte Carlo Method for Simulation of Light Propagation in Biological Tissue

Zhongguo Jiguang/Chinese Journal of Lasers 2025年第9期52卷

作者： Zhang, Hao Liu, Yifeng Wu, Wenjuan Li, Dong Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Objective The Monte Carlo (MC) method has become a cornerstone for simulation of light propagation in biological tissues, particularly for applications in laser therapy and medical imaging. However, traditional voxel-based Monte Carlo (VMC) methods often exhibit significant errors when dealing with complex curved surfaces due to the inherent limitations of structured grid discretization. By contrast, tetrahedron-based Monte Carlo (TMC) methods, based on unstructured meshes, offer better adaptability to complex geometries but incur higher computational cost. This study aims to address the trade-off between computational efficiency and accuracy in light propagation simulations by proposing a novel correction method to improve the performance of VMC in handling curved interfaces with large refractive index differences. The objective is to enhance the accuracy of VMC while maintaining its computational efficiency, making it more viable for practical biomedical applications, such as laser treatment and optical diagnosis. Methods This study compares the performance of VMC and TMC in light propagation simulations under different refractive index conditions. We propose a coordinate transformation-based correction method to reduce the errors in VMC caused by the inaccurate handling of reflection and refraction at curved interfaces. The simulations were carried out on a multi-layer skin tissue model with varying refractive index conditions;the laser light was directed at blood vessels embedded within the dermis. The correction method involves transforming the photon direction vector in a way that accounts for the curvature of the interface, thereby improving the accuracy of light photon interactions at the tissue boundaries. Simulations were conducted using MATLAB, and the results were validated through experimental cases, such as diabetic retinopathy laser treatment. The computational setup included an Intel i7-9700K processor and an NVIDIA GTX 3080 graphics card (GPU). Resu

关键词： Laser surgery

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Understanding Copper Corrosion in Bentonite-Enriched Environments: Insights from the Point Defect Model

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SSRN 2024年

作者： Ning, Zhiyuan Zhou, Qulan Li, Na Macdonald, Digby D. Zhou, Jie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States Xi’an Aerospace Propulsion Institution Xi’an China

The laboratory simulated copper corrosion in a bentonite/groundwater solution, analyzing the kinetics of metal passivation through potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy experiments. Corrosion development patterns were inferred from morphological characterization, and the mechanisms by which bentonite affects copper corrosion were comprehensively elucidated based on the point defect model. The research revealed that bentonite affects copper corrosion resistance through Donnan exclusion, cation adsorption, and hydrolysis of salts. Based on the point defect model, the study elucidated the microscopic mechanism of pitting corrosion induced by bentonite hydrolysis salts, calculating the polarizability of the passive layer/outer layer interface as α = 0.1. The reliability of the cation adsorption and adsorption-desorption mechanisms was confirmed through experimental data fitting, point defect model fitting, and theoretical analysis. © 2024, The Authors. All rights reserved.

关键词： Hydrolysis

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X-ray computed tomography (XCT) study of jetting in a fluidized bed: Effects of two-component fluidization

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Particuology 2025年 102卷 264-274页

作者： Xiang, Zhong Chen, Xi Liu, Shuguang Heindel, Theodore J. School of Energy and Environment Southeast University Nanjing210096 China State Key Laboratory of Low-carbon Smart Coal-fired Power Generation and Ultra-clean Emission Southeast University Nanjing210096 China Center for Multiphase Flow Research and Education and Department of Mechanical Engineering Iowa State University AmesIA50011 United States

Fluidization of non-spherical particles is commonly found in the biomass and solid waste processing industry, and the jetting characteristic above the aeration plate is critical to the fluidization performance of these particles. In this study, cylindrical particles are used as typical non-spherical particles and co-fluidized with small bed material particles. X-ray computed tomography (XCT) is used to reconstruct the 3D structure of the aeration plate region, allowing for the identification of individual aeration jets. The effects of jet velocity (Uj), cylindrical particle mass fraction (ω), cylindrical particle density (ρi), and the cylindrical particle sphericity () on jet shape and volume are investigated. The experimental results indicate that decreasing the cylindrical particle mass fraction (ω) and particle density (ρi) increases the jet length (L), maximum jet diameter (D), and maximum jet volume (V), but have little effect on the jet half angle (θ). The cylindrical particle density (ρi) is the most sensitive factor for jet shape, while the effect of cylinder particle sphericity () on jet shape is insignificant. A correlation of jet length (L) in a two-component fluidized bed with cylindrical particles and bed material is proposed based on all the experimental results. © 2025 Chinese Society of Particuology and Institute of Process engineering, Chinese Academy of Sciences

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Mild Combustion of a Premixed Nh3/Air Jet Flame in Hot Coflow Versus its Ch4/Air Counterpart

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SSRN 2023年

作者： Li, Pengfei Wang, Guochang Liu, Xiangtao Shi, Guodong Cai, Xiao Liu, Zhaohui Mi, Jianchun State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China College of Engineering Peking University Beijing100871 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Dalian Maritime University China

MILD combustion is very suitable for solving the problems of unstable flame and high NOx emission (ENOx ) for ammonia fuel, but the related studies are rare. This work numerically investigates the MILD combustion characteristics of a premixed NH3/air jet flame in hot coflow (JHC) under different jet equivalence ratio (ΦJ), coflow temperature (TC) and oxygen level (XO2,C). For comparison, the similar CH4/air MILD-JHC flames are also calculated. Results show that the NH3 flame generally has lower temperature rise and heat release as well as larger reaction zone than CH4. This may suggest that the former flame can develop to the MILD regime more easily. ENOx is two orders higher from the NH3 than CH4 flame at all TC and XO2,C for ΦJ 1. ENOx of the NH3 flame quickly drops to near zero, but ENH3 and EH2 are very high (~1.00 ppm) and the combustion efficiency is low. Moreover, ENOx increases quickly (slowly) with XO2,C (TC) while ENH3 and EH2 are quite low at TC ≥ 1.00 K and XO2,C ≥ 1. for the NH3 flame. ENOx mainly comes from NO but N2O is also important at low ΦJ and TC. Therefore, considering all ENOx , ENH3, EH2 and the burning efficiency, the optimal conditions for NH3 MILD combustion are ΦJ =1. TC ≥ 1.00 K and XO2,C =1.-3%. In addition, compared to the conventional flame, the NH3 MILD combustion can reduce ENOx by 1.2 orders. © 2023, The Authors. All rights reserved.

关键词： Ammonia

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Effect of Fuel System on the Heat Releasing Method and flow-Path Design of Rocket-Based Combined Cycle Engine

Effect of Fuel System on the Heat Releasing Method and Flow-...

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International Conference on Mechanical and Aerospace engineering (ICMAE)

作者： Xiao Liu Yinhu Wang Yiyan Yang Lei Shi Dekun Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Beijing Institute of Long March Vehicle Beijing China Science and Technology on Combustion Internal Flow and Thermal-structure Laboratory Northwestern Polytechnical University Xi’an China

Multi-components rocket-based combined cycle (RBCC) engine is widely applied in most two-stage-to-orbit program due to stable operation performance under variable flight conditions. Present researches numerically compared RBCC’s performance under ramjet mode and scramjet mode, respectively, by using two fuel system, hydrogen and kerosene together with a $\mathrm{k}-\omega$ SST turbulence model. Researches showed that the combustor area ratio should be increased to keep stable pressure difference balance between inflow and flame because of higher caloric value using hydrogen. Distributed heat addition method is benifit for overall performance improvement when using hydrogen. Different from using kerosene, head should be delayedly added in combustor downtream under scramjet mode. Moreover, the advanced heat addition amount should be decreased under ramjet mode to ensure effective isolator operation.

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Uncertainty and Sensitivity Analysis of Containment Aerosol Removal Under Severe Accident

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SSRN 2025年

作者： Ou, Pingwen Chen, Yongzheng Chen, Peng Ouyang, Yong Guo, Chao Su, Guanghui China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China State Key Laboratory of Nuclear Power Safety Technology and Equipment China Nuclear Power Technology Research Institute Co. Ltd. Shenzhen518000 China School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

This study focuses on the uncertainty and sensitivity analysis of containment aerosol removal under severe accident conditions using the severe accident integral code ASTEC, validated by experiments carried by CNPRI, and the coupled uncertainty and sensitivity tool SUNSET. A "separated" methodology is introduced, which distinguishes between thermal-hydraulic and aerosol boundary conditions to highlight the impact of containment aerosol mechanisms. Eleven uncertainty input parameters related are selected for uncertainty propagation and the Spearman correlation coefficient is utilized to describe sensitivity. The removal factor exhibits significant variation, with peaks due to temporary enhancement of diffusiophoresis deposition caused by corium relocation and subsequent steam generation. Uncertainty in the removal factor is substantial before aerosol release termination and narrows afterward. The gravitational settling and the diffusiophoresis deposition are the most important contributors with approximately 70% and 20% deposited aerosol mass, respectively. The initial mass medium diameter, the gravitational shape factor and the agglomeration shape factor are the most influential input parameters in aerosol removal, including in-containment deposition and environmental release, and they should be considered discreetly with conservatism in source term estimation and radioactive consequence evaluation in nuclear engineering. © 2025, The Authors. All rights reserved.

关键词： Sensitivity analysis

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Life-Cycle-Based Multi-Objective Optimal Design and Analysis of Distributed Multi-Energy Systems for Data Centers

SSRN

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SSRN 2023年

作者： Ren, Xiaoxiao Han, Zijun Ma, Jinpeng Xue, Kai Chong, Daotong Wang, Jinshi Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China China Energy Construction Group Shaanxi Electric Power Design Institute Co. Ltd Xi’an710043 China

The widespread deployment of data centers has contributed to a dramatic increase in energy consumption and carbon emissions. To solve this problem, this study proposes a distributed multi-energy system (DMES) driven by solar, wind, geothermal and natural gas and its life-cycle-based multi-objective optimization model considered energy, economy and environment. This model employs an improved multi-objective grasshopper optimization algorithm (IMOGOA) based on the population variation mechanism and a novel operation strategy depending on load characteristics. On this basis, the effects of carbon tax, life span and indoor temperature set-point determined by improved predicted mean vote (PMV) on the system are further explored. Case studies are conducted on a practical data center in Qinghai, China. The results show that the IMOGOA is more suitable for the optimization of DMES than the commonly used algorithms. Besides, the supply of cooling, heating and electricity can meet the needs of the data center, and more than 30% of electricity is generated from renewable sources. Finally, the carbon tax, life span and indoor temperature set-points affect the optimization of the system. The methodology and results can be expected to be of great technical interest for the energy supply systems of data centers. © 2023, The Authors. All rights reserved.

关键词： Life cycle

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Experimental Study on the flow Characteristics of a Plate with a Mechanically Choked Orifice

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Fluid Dynamics & Materials Processing 2021年第1期17卷 97-107页

作者： Ming Liu Xingkai Zhang Dong Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Petroleum Engineering Technology Research Institute of Shengli Oilfield Company SINOPECDongying257000China Shandong Key Laboratory of Heavy Oil Production Technology Shengli Oilfield CompanySINOPECDongying257000China Petroleum Engineering College Yangtze UniversityWuhan430100China

The mechanically choked orifice plate (MCOP) is a new type of device for flow control by which choking conditionsfor incompressible fluids can be obtained with relatively small pressure losses. Given the lack of relevant results anddata in the literature, in the present study, we concentrate on the experimental determination of the flow coefficientfor the annular orifice, the pressure distribution in the MCOP, and the characteristics of the choked flow itself. Asconfirmed by the experimental results, the Reynolds number, the orifice plate thickness, the plug taper, and theeccentricity have an obvious influence on the aforementioned flow coefficient. The pressure drop in the MCOPis mainly generated near the orifice plate, and the pressure upstream of the orifice plate is slightly reduced in theflow direction, while the pressure downstream of the orifice plate displays a recovery trend. The choked flow rateof the MCOP can be adjusted by replacing the spring with a maximum flow control deviation of 4.91..

关键词： Mechanical choked orifice plate flow control flow coefficient flow characteristics

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Hydrodynamic Characteristics Prediction Models for Water-Cooled Wall Under Different Loads Based on Artificial Neural Network

SSRN

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SSRN 2024年

作者： Yang, Jiahui Zhang, Yong Li, Ruiyu Han, Lei Yue, Yang Wang, Jin Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Yantai Longyuan Power Technology Co. Ltd Yantai264000 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China

Real-time monitoring of hydrodynamic characteristics in water-cooled wall is crucial for boiler safety. Comprehensive numerical simulations are employed in this study to determine the heat flux distribution on the water-cooled wall across 38 different operating conditions. The heat flux results are applied to calculate hydrodynamic characteristics. Subsequently, the hydrodynamic characteristics results, along with the corresponding operating parameters, form the dataset for the Artificial Neural Network (ANN) models. The proposed methodology generates high-quality datasets, with a maximum root mean square error (RMSE) of only 6.8 K when comparing the results of working fluid temperature to the measured values. Two dataset partitioning methods are compared. Compared with random partitioning (control group), Considering each working condition as a whole during dataset partitioning (experimental group) reduces the average RMSE of predicted results in the test set by 47.6%, along with a 31.8% decrease in average number of neurons. The developed models exhibit excellent agreement with four working conditions in the test set, both in trends and absolute values, with acceptable error ranges. On the validation and test sets, the maximum RMSEs between the predicted and calculated values for flow rate, pressure, temperature and enthalpy are 0.033 kg s-1. 0.49 MPa, 5.7 K and 89.5 kJ kg-1. respectively, underscoring the reliability and practicality of the predictive models. © 2024, The Authors. All rights reserved.

关键词： Hydrodynamics

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Experimental Study on Deliquification with Atomizing Nozzle in Gas Well

Experimental Study on Deliquification with Atomizing Nozzle ...

引用

2020 International Conference on Green Energy, Environment and Sustainable Development, GEESD 2020

作者： Gao, Yutang Li, Xiaobai Chang, Peng Liu, Lei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Shaanxi710049 China

Gas is a clean energy resource in comparison with oil and coal. Liquid-loading problem is frequently encountered in the process of gas production. It would directly cause the production of gas wells decreasing, even off production. A number of deliquification techniques have been suggested for solving this kind of problem, but the available techniques are not yet widely applicable. Based on the analysis, the method of deliquification with atomizing nozzle in gas wells was put forward. The test bench was designed for studying the atomization of nozzles and the liquid entrainment of gas flow. The size distribution of atomized droplets was measured by Malvern laser grain size analyzer. The Sauter mean diameters of atomized droplets were analysed under different two-phase flow conditions. The results indicate that the designed nozzles have good atomization performances and show potential application for reducing liquid loading in gas wells. © Published under licence by IOP Publishing Ltd.

关键词： Two phase flow

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