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Thermally Conductive Polyimide/Boron Nitride Composite Films with Improved Interfacial Compatibility Based on Modified Fillers by Polyimide Brushes

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Chinese Journal of Polymer Science 2023年第12期41卷 1921-1936,I0009页

作者： Meng-yan Gao Lei Zhai Song Mo yan jia Yi Liu Min-Hui He Lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics *** one of the key technical challenges to be solved,interfacial compatibility between filler and matrix plays an important role for composite ***,boron nitride was modified by grafting polyimide brushes via a twostep method,and a series of thermally conductive polyimide/boron nitride composite films were *** characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced,resulting in a significant reduction in defects and interfacial thermal *** interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler *** a result,composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine *** strength can reach up to 80 MPa even if the filler content is as high as 50 wt%.The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m^(-1)·K^(-1),*** addition,thermal and dielectric properties of composite films were also enhanced to some *** above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.

关键词： Polyimide Composite film Boron nitride Thermal conductivity Interfacial compatibility

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Ultrasound elastography for evaluating stiffness of the human lens nucleus with aging:a feasibility study

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International Journal of Ophthalmology(English edition) 2021年第2期14卷 240-244页

作者： Hai-yan Zhou Hong yan Wei-jia yan Xin-Chuan Wang Department of Ophthalmology Shanxi Provincial People’s HospitalThird Affiliated Hospital of the School of MedicineXi’an Jiaotong UniversityXi'an 710068Shanxi ProvinceChina Department of Ophthalmology Xi’an No.4 HospitalShanxi Eye HospitalAffiliated Guangren Hospital School of MedicineXi’an Jiaotong UniversityXi'an 710004Shanxi ProvinceChina Medical School the University of SheffieldWestern BankSheffield S102TNUK Shanxi Traditional Chinese Medicine Hospital Xi'an 710003Shanxi ProvinceChina

AIM:To investigate the significance of ultrasound elastography for evaluating stiffness of the human lens nucleus in volunteers with different ***:A total of 90 volunteers(lens transparency,uncorrected visual acuity≥0.5,intraocular pressure:14-19 mm Hg)were divided into 3 groups according to age:Group A(30 people,median age:82±3.5 y,mean axial lengths 23.7±0.5 mm);Group B(30 people,median age:46±2.1 y,mean axial lengths 23.9±0.4 mm);and Group C(30 people,median age:22±3.5 y,mean axial lengths 24.0±0.4 mm).Lens nuclear stiffness was measured by Free-hand qualitative elastography by independent *** gray scale and color-coded elastography maps were *** each case,three consecutive detections were performed and strain ratio was used for statistical ***:Elastography analysis showed excellent diagnostic performance for lens *** strain ratio was lowest(0.03±0.01)%in Group A and highest(2.03±0.43)%in Group *** strain ratio was moderate(0.64±0.10)%in Group *** were significant differences between these three groups(P<0.05).The lens nucleus strain rate changes with *** aging,the lens nucleus strain rate and resilience decrease,demonstrating harder ***:The relationship between human lens stiffness and age is demonstrated by ultrasound *** age is associated with lower strain ratio and less resilience of the lens.

关键词： ultrasound elastography human lens nucleus stiffness

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Static Recrystallization Kinetics Model After Hot Deformation of Low-Alloy Steel Q345B

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Journal of Iron and Steel Research International 2010年第8期17卷 61-66页

作者： MA Bo PENG yan jia Bin LIU Yun-fei State Key Laboratory of Metastable Materials Science and Technology Engineering Research Center of Rolling Equipmentand Complete Technology of Ministry of EducationYanshan UniversityQinhuangdao 066004HebeiChina

The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation *** results show that static recrystallization during the interpass time is *** the deformation temperature and strain increase,softening caused by static recrystallization is *** to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was ***,the error analysis of static recrystallization kinetics model proved that the model had good ***,this model provides a theoretical basis for static recrystallization（SRX）and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.

关键词： Gleeble-3500 low-alloy steel static recrystallization activation energy kinetics model

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Improved Bacterial Foraging Optimization Algorithm Based on Fuzzy Control Rule Base

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Journal of Electronic Science and Technology 2017年第3期15卷 283-288页

作者： Cui-Cui Du Xu-Gang Feng jia-yan Zhang School of Electrical and Information Engineering Anhui University of Technology Maanshan 243002

Manual construction of a rule base for a fuzzy system is the hard and time-consuming task that requires expert *** this paper we proposed a method based on improved bacterial foraging optimization（IBFO）,which simulates the foraging behavior of “***” bacterium,to tune the Gaussian membership functions parameters of an improved Takagi-Sugeno-Kang fuzzy system（C-ITSKFS） rule *** remove the defect of the low rate of convergence and prematurity,three modifications were produced to the standard bacterial foraging optimization（BFO）.As for the low accuracy of finding out all optimal solutions with multi-method functions,the IBFO was *** order to demonstrate the performance of the proposed IBFO,multiple comparisons were made among the BFO,particle swarm optimization（PSO）,and IBFO by MATLAB *** simulation results show that the IBFO has a superior performance.

关键词： Index Terms--Fuzzy control system Gaussian membership functions improved bacterial foraging optimization (IBFO) particle swarm optimization (PSO)

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2-D FLUID SIMULATION OF DUAL-FREQUENCY CAPACITIVELY COUPLED PLASMA

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Journal of Hydrodynamics 2009年第6期21卷 814-819页

作者： LU Yi-jia yan Da-qiang CHEN Yao-song LTCS and College of Engineering Peking University Beijing 100871 China

Dual-frequency aegon discharge at 100 m Torr is modeled with a 2-D fluid model in this study. The plate gap of the system is 20 ram, and discharges are modeled at High Frequency （HF） 40 MHz, 60 MHz, 80 MHz, Low Frequency （LF） 2 MHz, 5 MHz, 10 MHz, low-frequency voltage 50 V, 75 V, 100 V and high-frequency voltage 200 V, respectively. The spatial distribution of electron density and ion density and the periodic evolution of instantaneous electric potential in bulk plasma and sheath are discussed. The numerical results show that plasma density increases with HFs and LFs and LF voltage, while HFs has more effect on the density. It is concluded that improving the ratio of HFs/LFs and increasing LF voltages is a method to gain high density and high ion bombardment energy simultaneously based on the analysis of electric potential distribution.

关键词： dual frequency CCP discharge 2-D fluid model

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Anisotropy and Dissipation of Turbulence and Their Effects on Solar Models

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Chinese Journal of Astronomy and Astrophysics 2001年第1期1卷 66-76页

作者： yanLi jia－yanyang YunnanAstronomicalObservatoryandNAOCAS P.O.Box110Kunming650011 YunnanAstronomicalObservatoryandNAOCA

Based on a dynamic model for turbulent convection, we investigate the effects of dissipation and anisotropy of the turbulence on the convective energy transport. We introduce two time scales to describe the dissipation of the turbulence, and approximate the anisotropy of the turbulence by Rotta's proposal of 'return to isotropy'. The improved turbulence model results in an equation to determine the temperature gradient in the convection zone, which is of similar form as that of the MLT. We apply the improved MLT to solar models, and find that the increases of the anisotropy and decreases of the dissipation of the turbulence reduce the value of the convection parameter a, because these processes enhance the convective energy transfer rate. Compared with the observed solar p-mode frequencies, it is plausible that the dissipation of the turbulence in the solar convection zone should be fairly strong, while the degree of anisotropy of the turbulence plays a less significant role on the structure of the solar convection zone.

关键词： Sun: interior - turbulent convection - Sun: oscillations

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A robust compact least-squares reconstruction method for compressible turbulent flow simulations of complex configurations

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Chinese Journal of Aeronautics 2023年第12期36卷 113-138页

作者： jia yan Zhengyu NIU Xiaoquan yanG Jue DING Xiaolong TANG Peifeng WENG Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai 200072China School of Mechanics and Engineering Science Shanghai UniversityShanghai 200072China Shanghai University of Electric Power Shanghai 200090China

For the second-order finite volume method,implicit schemes and reconstruction methods are two main algorithms which influence the robustness and efficiency of the numerical simulations of compressible turbulent *** this paper,a compact least-squares reconstruction method is proposed to calculate the gradients for the distribution of flow field variables *** compactness of the new reconstruction method is reflected in the gradient calculation *** geometries of the face-neighboring elements are no longer utilized,and the weighted average values at the centroid of the interfaces are used to calculate the gradients instead of the values at the centroid of the face-neighboring ***,an exact Jacobian solving strategy is developed for implicit temporal *** accurate processing of Jacobian matrix can extensively improve the invertibility of the Jacobian matrix and avoid introducing extra numerical *** addition,a modified Venkatakrishnan limiter is applied to deal with the shock which may appear in transonic flows and the applicability of the mentioned methods is enhanced *** combination of the proposed methods makes the numerical simulations of turbulent flow converge rapidly and steadily with an adaptive increasing CFL *** numerical results of several benchmarks indicate that the proposed methods perform well in terms of robustness,efficiency and accuracy,and have good application potential in turbulent flow simulations of complex configurations.

关键词： Compact least-squares reconstruction method Exact Jacobian matrix Finite volume method Implicit schemes Turbulent flow

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Perturbative Influence on the Shockwave of Burgers Equation

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Chinese Physics Letters 2000年第3期17卷 157-158页

作者： TANG Yi yan jia-Ren ZHANG Kai-Wang Department of Physics Xiangtan UniversityXiangtan 411105 Department of Physics Hu Jnan Normal UniversityChangsha 410081

From the point of view of evolution equations with soliton solutions,we present a general way for the study of the shockwave of one-dimensional Burgers equation under the action of *** from the damping case which need... 详细信息

关键词： Burgers perturbations soliton

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Direct Approach Based on the Separation of Variables for the Soliton Study of Perturbed Sine-Gordon Equation

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Chinese Physics Letters 1997年第9期14卷 671-674页

作者： yan jia-ren TANG Yi CHEN Zhen-hua Department of Physics Hunan Normal UniversityChangsha 410081 Institute of Nonequilibrium Materials South-Central University of TechnologyChangsha 410083

A new direct approach based on the separation of variables for the study of soliton perturbations is *** an example,the effects of perturbation on a soliton(kink),i.e.,both the time-dependence of soliton parameters and the first-order correction are derived for perturbed sine-Gordon *** approach is very concise and easy to understand,and it can be extended directly to deal with other nonlinear evolution equations.

关键词： equation. equations. soliton

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Perturbation Theory for Optical Soliton

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Chinese Physics Letters 1998年第11期15卷 805-806页

作者： TANG Yi yan jia-ren ZHANG Kai-wang Department of Physics Xiangtan UniversityXiangtan 411105 Department of Physics Hu’nan Normal UnicersityChangsha 410081 Department of Scientific Research Xiangtan UniversityXiangtan 411105

Based on the main idea of the derivative expansion method,a perturbation approach is proposed for the investigation of single soliton propagating down a nonideal monomode optical *** approach is totally independent of inverse scattering theory,which has substantial difference from the past *** this scheme,the first-order correction is derived by the method of eigenfunction expansion,and the parameters change is directly obtained from the secularity conditions for some cases.

关键词： methods. expansion soliton

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