检索结果-内蒙古大学图书馆

Estimation of particle depth from two defocused images using the Fourier transform

Particuology 2020年第2期18卷 48-54页

作者： Wu Zhou Xu Luo Benting Chen Yukun Zhang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Depth from defocus is one technology for depth *** estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging *** images are processed with the Fourier transform to obtain the characteristic parameter(i.e.,the standard deviation of the relative blur kernel of these two defocused images).First,we theoretically analyze the functional relationship between the object depth and the standard deviation or variation of the relative blur ***,we verify the relationship *** analyze the influence of particle size,window size and image noise on the calibration curves using both numerical simulations and *** obtain the depth range and accuracy of this measurement system *** the verification experiments,we use a sample of glass microbeads and the irregularly-shaped dust particles on a microscope *** of these experiments present a suitable depth measurement ***,we apply the measuring system to the depth estimation of drops from a small anti-fogging *** results show that our system and image processing algorithm are robust for different types of particles,facilitating the in-line three-dimensional positioning of particles.

关键词： Depth from two defocused images Fourier transform Standard deviation of relative blur kernel Drops depth measurement Sensitivity and accuracy analysis

来源：评论

学校读者我要写书评

暂无评论

Research on the Influence of Helical Strakes on Dynamic Response of Floating Wind Turbine Platform

引用

China Ocean engineering 2017年第2期31卷 131-140页

作者： DING Qin-wei LI Chun School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 China

The stability of platform structure is the paramount guarantee of the safe operation of the offshore floating wind turbine. The NREL 5MW floating wind turbine is established based on the OC3-Hywind Spar Buoy platform with the supplement of helical strakes for the purpose to analyze the impact of helical strakes on the dynamic response of the floating wind turbine Spar platform. The dynamic response of floating wind turbine Spar platform under wind, wave and current loading from the impact of number, height and pitch ratio of the helical strakes is analysed by the radiation and diffraction theory, the finite element method and orthogonal design method. The result reveals that the helical strakes can effectively inhibit the dynamic response of the platform but enlarge the wave exciting force; the best parameter combination is two pieces of helical strakes with the height of 15%D （D is the diameter of the platform） and the pitch ratio of 5; the height of the helical strake and its pitch ratio have significant influence on pitch response.

关键词： floating wind turbine platform helical strakes orthogonal design

来源：评论

学校读者我要写书评

暂无评论

Investigation on the Transient Thermal Performance of a Mini-Channel Cold Plate for Battery Thermal Management

引用

Journal of Thermal Science 2021年第3期30卷 914-925页

作者： FANG Yidong SHEN Jiali ZHU Yue YE Fei LI Kang SU Lin School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Cold plate is an important component for a liquid battery thermal management *** order to study the transient thermal performance of the cold plate under conditions with sharply increasing heat loads,the numerical model of a battery cold plate is *** validation experiment shows that the error between the simulation and experiment is around 2.5%to 5%.Effects of the coolant flow rate,the increase in heat flux,and the channel number are analyzed to study the transient thermal performance of the cold *** show that the average temperature of the cold plate at 540 s is lowered from 28.3℃ to 26.9℃ when the coolant flow rate is raised from 0.065 kg/s to 0.165 kg/*** temperature deviation is decreased when the coolant flow rate is increased from 0.065 kg/s to 0.115 kg/s;however,it is slightly increased if the coolant flow rate is further *** average temperature and temperature deviation are raised if the final heat flux is increased from11000 W/m^(2) to 16500 W/m^(2),which are 2 and 3 times of the initial,*** addition,increasing the channel number has slightly positive effect on the average temperature of the cold plate,while the temperature deviation is increased when the channel number is increased from 3 to 11 due to the non-uniform velocity distribution between each *** results of this study will be helpful during the design of cold plate for battery thermal management,especially for transient conditions with sudden rising heat loads like thermal runaway.

关键词： battery thermal management cold plate transient analysis temperature distribution mini-channel

来源：评论

学校读者我要写书评

暂无评论

3D particle streak velocimetry by defocused imaging

引用

Particuology 2023年第1期72卷 1-9页

作者： Xiangrui Dong Xiaoxiao Wang Wu Zhou Fangting Wang Xinran Tang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai 200093China

Particle streak velocimetry (PSV) has become one of the important branches of flow filed measurements. It extracts velocity information from particle trajectories captured by single frame long exposure images. Since the defocus of moving particle is inevitable during a long exposure time and under a large magnification, a novel three-dimensional (3D) velocity measurement method named defocusing particle streak velocimetry (DPSV) is proposed in this paper. On the one hand, an extension from two-dimensional (2D) to 3D velocity measurement with a monocular system is carried out. The depth information of the particle, which reflects the position in the third dimension, is indicated by the defocusing degree (characteristic parameter σ) of the particle images. The variation of σ along the trajectory is recognized by surface fitting of the gray value distribution of particle images, assuming that σ varies linearly along the trajectory. On the other hand, based on the linear fitting for the straight trajectory, an arc fitting model is developed for curved trajectories which are commonly captured in turbulent flow. The relationship between σ and the particle depth position z is experimentally calibrated using a LED light and a diaphragm. Finally, the DPSV method is verified in a submerged jet flow field as well as in a microchannel flow field to obtain the 3D velocity field with single monocular system.

关键词： Defocusing particle streak velocimetry Curve trajectory Three-dimensional velocity Gray value distribution

来源：评论

学校读者我要写书评

暂无评论

Enhancing thin film boiling heat transfer through electric field and surface Macro-Structure Synergy: Insights from bubble dynamics modulation

引用

International Journal of heat and Mass transfer 2025年 249卷

作者： He, Changqiu Tian, Jiameng Chen, Yiqi Zhu, Yuchen Liu, Xin Wang, Hai Wang, Zhentao Cai, Benan Wang, Changqing Wang, Junfeng Zhou, Zhifu Chen, Bin School of Energy and Power Engineering Jiangsu University Zhenjiang212013 China School of Energy and Power Engineering Chongqing University Chongqing 400044 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Laboratory of Thermo-fluid Science and Nuclear Engineering School of Energy and Power Engineering Northeast Electric Power University Jilin 132012 China National Key Laboratory of Marine Engine Science and Technology Shanghai 201108 China

Improving boiling heat transfer in thin liquid films by employing external electrical fields and macro-structured surfaces presents promising for tackling the growing difficulties related to high-heat-flux thermal management in electronic devices. In this study, six distinct macro-structured surfaces are designed and fabricated to gain insight into how liquid film thickness, structural parameters, and applied voltage affect the efficiency of boiling heat transfer with ethanol as the coolant. High-speed imaging and precise heat transfer measurements are employed to characterize the boiling performance, providing insights into the underlying fundamentals driving the observed enhancements. Results reveal that applying a 4-kV voltage increases departure frequency of bubble by 86 % and a 28 % reduction in diameter, causing a 20 % improvement in critical heat flux (CHF). CHF is positively correlated with liquid film thickness and pin height, but negatively with pin spacing, achieving a 139 % increase under optimal conditions. Liquid film thickness was found to have the most significant impact on CHF, followed by pin spacing and applied voltage. By simplifying the void fraction equation, a new CHF correlation is proposed that introduces a dimensionless characteristic length, representing the relative effects between bubble size and film thickness, while accounting for the synergy between the electric field and surface macro-structure. © 2025 Elsevier Ltd

关键词： Electric heating

来源：评论

学校读者我要写书评

暂无评论

Unsteady wall effects on hydrodynamics and energy absorption in a flexible traveling wave plate: Roles of dimensionless wall distance and wave speed

引用

Renewable Energy 2025年 252卷

作者： Cui, Zhifei Bai, Yang Cao, Peiyu Huang, Diangui University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

This study investigates the hydrodynamic and energy absorption characteristics of a two-dimensional flexible traveling wave plate in energy absorption mode, focusing on the impact of unsteady wall effects and their interaction with the wake vortex structure. Numerical simulations reveal that the wall effect significantly alters both the time-averaged and instantaneous force coefficients, with variations depending on the dimensionless wave speed(C) and wall distance(D). Specifically, the time-averaged transverse force coefficient decreases by 45.9 % at D = 0.2 and C = 0.4 compared to unbounded conditions, while the longitudinal force coefficient exhibits a complex trend, transitioning from a monotonic decrease to a decrease followed by an increase, influenced by wave speed. The wall effect also disrupts the symmetry of the instantaneous force coefficients, complicating the force curves. Furthermore, the wall increases the average differential pressure power, slightly enhancing energy absorption efficiency at D = 0.8–1.0, but reducing efficiency at D = 0.2–0.7. The wall also disturbs the wake vortex structure, causing premature dissipation of the positive vortex core and weakening energy harvesting near the wall. These findings highlight the wall's complex influence on hydrodynamic performance and energy absorption, offering insights for energy-harvesting device design near the wall. © 2025 Elsevier Ltd

关键词： Light absorption

来源：评论

学校读者我要写书评

暂无评论

Dynamic Response of Offshore Wind Turbine on 3×3 Barge Array Floating Platform under Extreme Sea Conditions

引用

China Ocean engineering 2021年第2期35卷 186-200页

作者： LIU Qing-song MIAO Wei-pao YUE Min-nan LI Chun WANG Bo DING Qingwei School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Offshore wind farm construction is nowadays state of the art in the wind power generation ***,deep water areas with huge amount of wind energy require innovative floating platforms to arrange and install wind turbines in order to harness wind energy and generate *** conventional floating offshore wind turbine system is typically in the state of force imbalance due to the unique sway characteristics caused by the unfixed foundation and the high center of gravity of the ***,a floating wind farm for 3×3 barge array platforms with shared mooring system is presented here to increase stability for floating *** NREL 5 MW wind turbine and ITI Energy barge reference model is taken as a basis for this ***,the unsteady aerodynamic load solution model of the floating wind turbine is established considering the tip loss,hub loss and dynamic stall correction based on the blade element momentum(BEM)*** second development of AQWA is realized by FORTRAN programming language,and aerodynamic-hydrodynamic-Mooring coupled dynamics model is established to realize the algorithm solution of the ***,the 6 degrees of freedom(DOF)dynamic response of single barge platform and barge array under extreme sea condition considering the coupling effect of wind and wave were observed and investigated in *** research results validate the feasibility of establishing barge array floating wind farm,and provide theoretical basis for further research on new floating wind farm.

关键词： Barge floating platform extreme sea conditions dynamic response stability

来源：评论

学校读者我要写书评

暂无评论

Insight into the interaction between water and surfactant aerosol particles based on molecular dynamics simulations

引用

Particuology 2023年第6期77卷 128-135页

作者： Chao Zhang Zhichao Zhang Longxiang Bu Yang Yang Wei Xiong Yueshe Wang School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and TechnologyShanghai200093China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an710049China

The ubiquitous surfactant significantly influences the hygroscopic growth of atmospheric aerosol ***,knowledge on the morphology of surfactant particles after the adsorption of water is *** this study,the interaction between water and particles composed of surface active malonic acid(MA)or adipic acid(AA)are simulated based on the molecular dynamics *** key point is the combined effect of temperature and water content on the structural properties of particles and the surface propensity of surfactants at the equilibrium *** show that demixed structure 1 with the adsorption of water clusters on acid grain,mixed structure and demixed structure 2 with acids coating on water droplet can be *** temperature increasing from 160 K to 330 K the surface propensity of MA and AA increases first and then *** the standard atmospheric temperature(280-330 K),the surface propensity of MA and AA increases with increasing water content and alkyl group,and its sensitivity to temperature and water content varies ***,all surfactants at the particle surface orient their hydrophobic groups toward the *** findings improve our insight into the surfactant partitioning and further assist in more accurate prediction of the particle hygroscopic growth.

关键词： Aerosol particles Surfactant Surface propensity Hygroscopic growth Molecular dynamics

来源：评论

学校读者我要写书评

暂无评论

Liutex identification on hairpin vortex structures in a channel based on msfle and moving-PIV

引用

Journal of Hydrodynamics 2021年第6期33卷 1119-1128页

作者： Xin-ran Tang Xiang-rui Dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

The spatiotemporal evolution of hairpin vortex structures in a fully developed turbulent boundary layer is investigated qualitatively and quantitatively by using two image *** this paper,the moving single-frame and long-exposure(MSFLE)image method is used to intuitively track the evolution process of a hairpin vortex,while the moving particle image velocimetry(moving-PIV)method is applied for obtaining a moving velocity field for quantitative *** to the structural characteristics of the hairpin vortex,an inclined light sheet with an appropriate inclination of 53°is arranged to capture the complete hairpin vortex structure at Re_(θ)=97–*** addition,the core size and the rotational strength of a hairpin vortex are further defined and quantified by the Liutex vector *** evolution process of a complete hairpin vortex structure observed by MSFLE shows that the shear along the normal direction leads to an increasing strength of the hairpin vortex,accompanied by a lifting vortex head and a distance decrease between two vortex legs during the dissipation *** combining moving-PIV with the Liutex identification,the spatiotemporal evolution of four typical regions of a hairpin vortex projecting into a 53°cross-section is *** results show that the process from the generation to the dissipation of a single hairpin vortex can be well characterized and recorded by the Liutex based on the core size and rotational intensity,and the evolution process is consistent with the MSFLE *** to the statistics of vortex core size and rotation intensity along time,the evolution of the hairpin vortex necks and legs can be described as a process of enhancement followed by *** the vortex head,its evolution maintains longer attributed to its far-from-wall position,which consists of an absolute enhancement process(stage 1)with an increasing rotation strength and a constant core size,and an absolute dissipation(stage 2)with a dec

关键词： Turbulent boundary layer hairpin vortex moving single-frame and long-exposure moving particle image velocimetry(PIV) Liutex vortex identification method

来源：评论

学校读者我要写书评

暂无评论

Two-dimensional self-adapting fast Fourier transform algorithm for nanoparticle sizing by ultrafast image-based dynamic light scattering

引用

Particuology 2018年第6期16卷 74-84页

作者： Dechuan Zhang Xiaoshu Cai Wu Zhou Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Sdence and TechnologyShanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering (University of Shanghai for Sdence and Technology)Shanghai 200093China

In nanoparticle sizing using the ultrafast image-based dynamic light scattering (UIDLS)method,larger impurities and dark noise from the complementary metal-oxide-semiconductor (CMOS)detector affect measurement *** solve this problem,a two-dimensional self-adapting fast Fourier transform (2D-SAFFT)algorithm is proposed for *** light scattering images of nanoparticles are processed using 2D fast Fourier transforms,and a high-frequency threshold and a low-frequency threshold are then set using the self-adapting algorithm to eliminate the effects of the dark noise of the CMOS detector and the *** signals caused by the dark noise of the CMOS detector and the impurities are cut off using the high-frequency threshold and the low-frequency *** signals without the high- and low-frequency components are then processed again using an inverse Fourier transform to obtain new images without the dark noise and impurities *** mean diameters of the measured nanoparticles can be obtained from images obtained using *** standard latex nanoparticles (46,100, 203,508,994nm)and commercial nanoparticles (antimony-doped tin oxide,indium tin oxide,TWEEN- 80,nano-Fe,and nano-Al2O3)were measured using this new *** show that 2D-SAFFT can effectively eliminate the effects of dark noise from the CMOS detector and the impurities.

关键词： Dynamic light scattering Nanoparticle size Fast Fourier transform algorithm Spectrum segmentation

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：