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MARCHING CUBES BASED FRONT TRACKING METHOD AND ITS APPLICATION TO SOME INTERFACE INSTABILITY PROBLEMS

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Journal of Hydrodynamics 2011年第5期23卷 580-588页

作者： wang Jing-yi ZOU Jian-feng ZHENG Yao REN An-lu 不详 Department of Engineering Mechanics School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China

A front tracking method based on a marching cubes isosurface extractor, which is related filter generating isosurfaces from a structured point set, is provided to achieve sharp resolution for the simulation of non-diffusive interfacial flow. Compared with the traditional topology processing procedure, the current front tracking method is easier to be implemented and presents high performance in terms of computational resources. The numerical tests for 2-D highly-shearing flows and 3-D bubbles merging process are conducted to numerically examine the performance of the current methodology for tracking interfaces between two immiscible fluids The Rayleigh-Taylor （RT） and Richtmyer-Meshkov （RM） instability problems are successfully investigated with the present marching cubes based front tracking method.

关键词： interracial flow front tracking marching cubes bubbles merging process Rayleigh-Taylor (RT) instability Richtmyer- Meshkov (RM) instability

The influence of stress-dependent overpotential on dendrite growth in all-solid-state battery with cracks

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Science china(Technological Sciences) 2024年第8期67卷 2493-2504页

作者： ZHANG ZhenHua ZHANG Yong LIU Chang HOU Xu wang jie Department of Engineering Mechanics School of Aeronautics and AstronauticsZhejiang UniversityHangzhou 310027China zhejiang Laboratory Hangzhou 311100China Key Laboratory of Soft Machines and Smart Devices of zhejiang Province Zhejiang UniversityHangzhou 310027China school of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China

Dendrite growth is one of the main challenges in maintaining the service life of all-solid-state lithium-ion *** stress has been reported to significantly affect dendrite *** this study,to explain the effect of mechanical stress on electrochemical reactions in all-solid-state batteries,a modified phase-field model for dendrite growth is proposed by considering the stress-dependent *** growth under different mechanical loadings in an all-solid-state battery is investigated using the proposed *** with previous experimental results,the current result shows that compressive stress inhibits dendrite *** the stress concentration at the tips of processing-induced microcracks,the effects of the number and distribution of microcracks on dendrite growth are *** results show that the stress-concentration field induced at the tips of cracks or voids can change the morphology of dendrites and decrease their growth *** study provides a new perspective for explaining Li dendrite growth under mechanical stress and offers inspiration for prolonging the service life of all-solid-state batteries based on defect and stress regulation,which may be further realized in experiments by filling solid electrolytes with different types of nanofillers.

关键词： Butler–Volmer equation stress-dependent overpotential microcracks all-solid-state battery phase-field simulation

Method for determining effective flame emissivity in a rotary kiln incinerator burning solid waste

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Journal of zhejiang university-Science A(Applied Physics & Engineering) 2012年第12期13卷 969-978页

作者： Jin-cai DU1,2,Qun-xing HUANG1,Jian-hua YAN1 (1State Key Laboratory of Clean Energy Utilization,zhejiang university,hangzhou 31002.,china) (2school of aeronautics and astronautics,zhejiang university,hangzhou 31002.,china) 1. State Key Laboratory of Clean Energy Utilization Zhejiang University Hangzhou 310027 China 2. school of aeronautics and astronautics Zhejiang University Hangzhou 310027 China

Temperature is the most important parameter for the improvement of combustion efficiency and the control of *** order to obtain accurate flame temperatures in a rotary kiln incinerator using non-intrusive thermographic method,the effective flame emissivity was studied.A combined narrow-and wide-band model and Mie scattering method were used to calculate the radiative properties for gases and fly-ash particles under different combustion *** effects of the air/waste ratio and fly-ash particles on the effective flame emissivity were *** results of numerical calculations showed that the effective emissivity decreased from 0.90 to 0.80 when the air/waste ratio increased from 1.0 to 1.8,and the effect of the fly-ash particles was ignorable under the conditions discussed in this *** measurement results indicated that the accuracy of the thermographic temperature measurements improved significantly if the setting of the flame emissivity was adjusted according to the air/waste ratio.

关键词： Thermographic temperature measurement Effective flame emissivity Rotary kiln incinerator Air/waste equivalenceratio

Numerical investigation of the effect of sub-grid scale eddies on the dispersed particles by LES/FDF model

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Science china(Technological Sciences) 2010年第5期53卷 1304-1308页

作者： JIN HanHui1,CHEN SuTao1,CHEN LiHua1 & FAN JianRen2 1 school of aeronautics and astronautics,zhejiang university,hangzhou 31002.,china 2 State Key Lab of Clean Energy Utilization,zhejiang university,hangzhou 31002.,china 1. school of aeronautics and astronautics Zhejiang University Hangzhou 310027 China2. State Key Lab of Clean Energy Utilization Zhejiang University Hangzhou 310027 China

An LES/FDF model was developed by the authors to investigate the SGS effect on the particle motion in the gas-particle two-phase plane wake *** simulation results of dispersion rate for different particles were compared with the results without using the FDF *** was shown that the large eddy structure is the dominant factor influencing the particle diffu-sion in space for small particles(small Stokes-number particles),but for intermediate or large diameter particles,the influence of the sub-grid scale eddies on the dispersion rate is in the same order as that of the large *** sub-grid scale eddies increase the particle dispersion rate in most time,but sometimes they decrease the dispersion *** sub-grid scale particle dispersion rate is decided not only by the intensity of sub-grid scale eddies and the Stokes number of the particles,but also by the large eddy structure of the flow *** the particles in isotropic turbulence,the dispersion rate decreases as the particle diameter increases.

关键词： multiphase flow large eddy simulation filtered density function turbulence sub-grid

MULTI-MODE OF VORTEX-INDUCED VIBRATION OF A FLEXIBLE CIRCULAR CYLINDER

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Journal of Hydrodynamics 2011年第4期23卷 483-490页

作者： XIE Fang-fang DENG Jian ZHENG Yao school of aeronautics and astronautics Zhejiang University Hangzhou 310027 China

The vortex-induced vibration of a flexible circular cylinder is investigated at a constant Reynolds number of 1000. The finite-volume method on moving meshes is applied for the fluid flow, and the Euler-Bernoulli beam theory is used to model the dynamic response of a flexible cylinder. The relationship between the reduced velocity and the amplitude response agrees well with the experimental results. Moreover, five different vibrating modes appear in the simulation. From the comparisons of their vortex structures, the strength of the wake flow is related to the exciting vibrating mode and different vortex patterns arise for different vibrating modes. Only 2P pattern appears in the first vibrating mode while 2S-2P patterns occur in the other vibrating modes if monitoring at different sections along the length of the cylinder. The vibration of the flexible cylinder can also greatly alter the three-dimensionality in the wake, which needs further studies in our future work, especially in the transition region for the Reynolds number from 170 to 300.

关键词： multi-mode Vortex-Induced Vibration (VIV) three-dimensional instability flexible cylinders Euler-Bemoulli beam

移动容迟网络中基于改进随机路点模型的移动连接路由

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吉林大学学报（工学版） 2011年第S1期41卷 297-303页

作者：李晖浙江大学航空航天学院杭州310027

在移动容迟网络中,考虑到稀疏网络节点混存长时间被无效消息占用情况,将移动连接路由算法与倒数计时器和快速缓存释放策略相结合,提出了加速缓存释放的移动连接路由算法,并研究了节点移动速率、通信距离、节点数量、消息有效时间、场景... 详细信息

在移动容迟网络中,考虑到稀疏网络节点混存长时间被无效消息占用情况,将移动连接路由算法与倒数计时器和快速缓存释放策略相结合,提出了加速缓存释放的移动连接路由算法,并研究了节点移动速率、通信距离、节点数量、消息有效时间、场景尺寸等对算法性能的影响。结果表明:该路由算法在保证传输可靠性的前提下能够提高网络的传输效率。

关键词：通信技术移动延迟网络随机路点模型路由缓存释放

Significantly enhanced performance and conductivity mechanism in Nb/Mn co-doped CaBi_(4)Ti_(4)O_(15)ferroelectrics

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Journal of Materiomics 2024年第3期10卷 652-669页

作者： Jiageng Xu Shaoxiong Xie Qian Xu jie Xing Qingyuan wang Jianguo Zhu school of aeronautics and astronautics Sichuan UniversityChengdu610000China Institute for Advanced Study Chengdu UniversityChengdu610106China Department of Mechanical Engineering Kyushu UniversityFukuoka819-0395Japan College of Architecture and Environment Sichuan UniversityChengdu610065China College of Material Science and Engineering Sichuan UniversityChengdu610065China

With the rapid development of high-end industries,the demand for high-temperature piezoelectric materials is significantly ***,realizing the ultra-high performance to meet more ap-plications still faces major scientific and engineering challenges of our ***,a new Nb/Mn co-doped CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric material system of CaBi_(4)Ti_(4-x)(Nb_(2/3)Mn_(1/3))_(x)O_(15)was synthesized by the conventional solid-state sintering *** results show that the addition of the dopants tends to break the long-range ferroelectric chain and soften the flexibility of polarization,resulting in more distorted crystal structure and better ferroelectric properties of CBT *** ultra-high piezoelectric constant(d_(33)=26.8 pC/N)is thus attained in CBT-based ceramics with x=0.12,which is about several times larger than that of pure CBT ***,numerous nano-sized layered domain structures that lie on the lateral plane of grains are observed in ceramics,with lower domain wall energy and better dynamic features under electric fields,mainly responsible for the origin of enhanced ***,excess dopants could make the conductivity mechanism of CBT ceramics transform from p-type to n-type,and also result in a shift of conduction relaxation mechanism from defect dipole rotation polarization to electron relaxation *** work not only provides a promising candidate for high-temperature piezoelectric materials,but also opens a window for opti-mizing performance by tailoring domain structures using chemical modification.

关键词： CaBi_(4)Ti_(4)O_(15) Lattice distortion Electrical performance Domain structure Conductivity mechanism

An oblivious fragile watermarking scheme for images utilizing edge transitions in BTC bitmaps

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Science china(Information Sciences) 2012年第11期55卷 2570-2581页

作者： ZHANG Yong1,LU ZheMing2 & ZHAO DongNing1 1ATR National Defense Technology Key Laboratory,College of Information Engineering,Shenzhen university,Shenzhen 518060,china 2school of aeronautics and astronautics,zhejiang university,hangzhou 31002.,china 1. ATR National Defense Technology Key Laboratory College of Information Engineering Shenzhen University Shenzhen 518060 China2. School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China

As one of the famous block-based image coding schemes,block truncation coding(BTC) has been also applied in digital *** BTC-based watermarking or hiding schemes usually embed secret data by modifying the BTC encoding stage or BTC-compressed data,obtaining the watermarked image with poorer quality than the BTC-compressed *** paper presents a new oblivious image watermarking scheme by exploiting BTC *** the traditional schemes,our approach does not really perform the BTC compression on images during the embedding process but utilizes the parity of the number of horizontal edge transitions in each BTC bitmap to guide the watermark embedding and extraction *** embedding process starts by partitioning the original cover image into non-overlapping 4×4 blocks and performing BTC on each block to obtain its BTC *** watermark bit is embedded in each block by modifying at most three pixel values in the block to make sure that the parity of the number of horizontal edge transitions in the bitmap of the modified block is equal to the embedded watermark *** the extraction stage,the suspicious image is first partitioned into non-overlapping 4×4 blocks and BTC is performed on each block to obtain its ***,by checking the parity of the number of horizontal edge transitions in the bitmap,we can extract one watermark bit in each *** results demonstrate that the proposed watermarking scheme is fragile to various image processing operations while keeping the transparency very well.

关键词： fragile image watermarking oblivious watermarking block truncation coding data hiding image authentication

Convenient room-temperature synthesis of sulfur and nitrogen co-doped NiCo-LDH coupled with CNTs on NiCo foam as battery-type electrode for high performance hybrid supercapacitor

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Rare Metals 2024年第9期43卷 4286-4301页

作者： Li Song Xiao-Hong Zhong Fang-Lin wang Zhi-Hui Huang Zhe Hong Yun-Fang Gao Hai-Dong wang Jian-Wei Ren Sheng-jie Peng Lei Li College of Biological Chemical Sciences and EngineeringJiaxing UniversityJiaxing 314001China College of Chemical Engineering Zhejiang University of TechnologyHangzhou 310014China College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Research and Development Department Jiangxi Ganfeng LiEnergy Technology Co.Ltd.Xinyu 338000China Department of Mechanical Engineering Science University of JohannesburgAuckland ParkJohannesburg 2092South Africa

The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is ***,the carbon nanotubes(CNTs)coupled with lowcrystalline sulfur and nitrogen co-doped Ni Co-LDH(denoted as SN-Ni Co-LDH)nanosheets array are grown on Ni Co foam(NCF)substrate by two convenient steps of metal induced self-assembly and corrosion engineering,which present the advantages of operating at roomtemperature and low preparation *** from the S–N co-doping and low-crystallinity of Ni Co-LDH,the prepared SN-Ni Co-LDH@CNTs@NCF electrode presents a topping charge capacity of 2470 C·g^(-1)(4.94 C·cm^(-2))at 5 m A·cm^(-2).Furthermore,the fabricated asymmetry supercapacitor(ASC)achieves an extraordinary energy density of 77 Wh·kg^(-1)(0.617 m Wh·cm^(-2))at a power density of 438 W·kg^(-1)(3.5 m W·cm^(-2))and outstanding stability(91%capacity retention after 5000 cycles at20 m A·cm^(-2)).Impressively,the structure evolution of Ni Co-LDH during the charge/discharge processes has been thoroughly elucidated by in-situ Raman ***,this work verifies a powerful strategy and practical value for preparing composite electrodes with high supercapacitance performance,and also provides guidance for the rational design of the smart electrodes.

关键词： Supercapacitor NiCo-LDH Carbon nanotubes Sulfur and nitrogen co-doped Convenient synthesis