检索结果-南通市图书馆

Simulation of space heavy-ion induced primary knock-on atoms in bipolar devices

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第1期33卷 573-580页

作者：张彬姜昊徐晓东应涛刘中利李伟奇杨剑群李兴冀 School of Physics Harbin Institute of TechnologyHarbin 150001China School of Material Science and Engineering Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi'an 710024China

Bipolar junction transistors(BJTs) are often used in spacecraft due to their excellent working characteristics. However,the complex space radiation environment induces primary knock-on atoms(PKAs) in BJTs through collisions, resulting in hard-to-recover displacement damage and affecting the performance of electronic components. In this paper, the properties of PKAs induced by typical space heavy ions(C, N, O, Fe) in BJTs are investigated using Monte Carlo simulations. The simulated results show that the energy spectrum of ion-induced PKAs is primarily concentrated in the low-energy range(17eV–100eV) and displays similar features across all tested ions. The PKAs induced by the collision of energetic ions have large forward scattering angles, mainly around 88°. Moreover, the distribution of PKAs within a transistor as a function of depth displays a peak characteristic, and the peak position is linearly proportional to the incident energy at a certain energy range. These simulation outcomes serve as crucial theoretical support for long-term semiconductor material defect evolution and ground testing of semiconductor devices.

关键词： Monte Carlo simulation primary knock-on atom(PKA) space-heavy ion radiation damage

Symmetric and Asymmetric Rolling Pure Copper Foil: Crystal Plasticity Finite Element Simulation and Experiments

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2015年第8期28卷 1024-1033页

作者： Shou-Dong Chen Xiang-Hua liu li-zhong liu State Key Laboratory of Rolling and Automation Northeastern University School of Materials and Metallurgy Northeastern University

A systematic study has been conducted aiming to attain an insight into the influence of coefficient of roll speed asymmetry, crystal orientation and structure on the deformation behavior, and crystallographic orientation development during foil rolling. Simulations were successfully carried out by using crystal plasticity finite element method（CPFEM）,and a novel computational framework is presented for the representation of virtual polycrystalline grain structures. It has been found that asymmetric rolling（ASR） is more efficient in producing plastic deformation since it develops additional shear strain and activity of slip system compared with symmetric rolling（SR）. For ASR, increase in the length of the shear zone, and decrease in the amount of the pressure and roll force would lead to further reduction. The shear strain path in SR and ASR is strictly influenced by the misorientation of neighbor grains, and corresponding {1 1 1} pole figures offer direct evidence of the spread of crystallographic orientation around the normal direction. The activity of slip systems was examined in detail and found that the predicted results are consistent with the surface layer model. The accuracy of the developed CPFEM model is verified by the fact that the simulated results of roll force coincide well with the experimental results.

关键词： Foil rolling Shear deformation Polycrystals model Finite element analysis

Photochemical Selective Desilylation of t-Butyldimethylsilyl Ethers

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2001年第2期12卷 95-98页

作者： Mei zhong JIN li YANG Long Ming WU You Cheng liu zhong li liu National Laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000

A photochemical desilylation reaction with nearly quantilative yield and excellent selectivity between silyl alkyl ether and silyl enol ether is reported.

关键词： photoinduced electron transfer selective desilylation

Photochemical Reduction of Aromatic Imines by 2-Phenyl-N, N-dimethylbenzimidazoline

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2001年第4期12卷 307-308页

作者： Mei zhong JIN li YANG Long Ming WU You Chen liu zhong li liu National Laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000

A series of aromatic imines were reduced to corresponding amines in excellent yields by 2-phenyl-N. N-dimethylbenzimidazoline (PDMBI) photochemically in the presence of magnesium perchloride (Mg(ClO4)(2)). A Mg2+ medi... 详细信息

关键词： Photoinduced electron transfer selective reduction imine PDMBI

ZrCl_4/Hantzsch 1,4-dihydropyridine as a new and efficient reagent combination for the direct reductive amination of aldehydes and ketones with weakly basic amines

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2007年第4期18卷 458-460页

作者： Zhen Gang liu Nan li li Yang zhong li liu Wei Yu State Key Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000 China

ZrCl4/Hantzsch 1,4-dihydropyridine is a mild and highly efficient reagent combination for the direct reductive amination. Weakly basic amines such as anilines substituted by electron-withdrawing group and heteroaromatic amines can be reductively alkylated with electron rich aldehydes and ketones under mild conditions to form the secondary amines in excellent yields.

关键词： Zirconium tetractfloride Hantzsch 1,4-dihydropyfidine Reductive amination

Ferric Chloride Catalyzed Isomerization and Cyclization of Geraniol, linalool and Nerol

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2002年第6期13卷 495-496页

作者： Wei YU Miao WEN li YANG zhong li liu National Laboratory of Applied Organic Chemistry Lanzhou UniversityLanzhou 730000

Ferric chloride catalyzes the isomerization and cyclization of geraniol, linalool and nerol in acetonitrile giving a-terpineol in good to high yields.

关键词： FeCl3 catalysis cyclization geraniol linalool nerol a-terpineol.

Different thermal fatigue behaviors between gray cast iron and vermicular graphite cast iron

在线全文

学校读者我要写书评

暂无评论

China Foundry 2022年第3期19卷 245-252页

作者： Gui-quan Wang zhong-li liu Yan-xiang li Xiang Chen School of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005ShandongChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationTsinghua UniversityBeijing 100084China

The initiation and propagation of thermal fatigue cracks in gray cast iron and vemicular graphite cast iron were investigated by Uddeholm method to reveal the complex thermal fatigue behaviors of cast *** of thermal fatigue behaviors of gray cast iron and vemicular graphite cast iron were observed and *** is found that the observed differences are related to the combination of graphite morphology and the oxidization of *** oxidized matrix is observed in gray cast iron due to its large specific surface *** brittle oxidized matrix facilitates the propagation of microcracks along the oxidization *** contrast,the radial microcracks are formed in vermicular graphite at the edge of graphite due to fewer oxidization *** indicates that the thermal fatigue resistance of gray cast iron is dominated by graphite content and morphology while that of vermicular graphite cast iron strongly relates to the strength of the matrix.

关键词： thermal fatigue gray cast iron vermicular graphite cast iron oxidization cracking propagation

Effects of alloying elements on thermal conductivity of pearlitic gray cast iron

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第9期26卷 1022-1030页

作者： Gui-quan Wang Xiang Chen Yan-xiang li Yuan liu Hua-wei Zhang zhong-li liu School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China School of Nuclear Equipment and Nuclear Engineering Yantai UniversityYantai 264005ShandongChina Key Laboratory for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084China

A quantitative model is proposed to describe the thermal conductivity of alloyed pearlitic gray cast iron. The model is built by combining the computational thermodynamics and effective medium theory. The volume fractions and concentrations of precipitated phases in as-cast structure are estimated in consideration of partial and para-equilibrium. The conductivity of alloyed ferrite is calculated, taking into account the electronic and vibrational contributions of alloying elements. The model provides a good agreement with microstructure analysis and measured thermal conductivity. The influence of common alloying elements was discussed from the viewpoint of precipitation of phases and scattering of alloying atoms. This model can also be used as a numerical tool for designing the pearlitic gray cast irons with high thermal conductivity and high tensile strength.

关键词： Thermal conductivity Thermodynamic model Gray cast iron Alloying element

Pd/C-catalyzed selective reduction of aromatic azides with Hantzsch 1,4-dihydropyridine

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2008年第8期19卷 885-888页

作者： Zhen Gang liu Xiu Qin Niu Wei Yu li Yang zhong li liu State Key Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 730000 China

The reagent combination of Hantzsch 1,4-dihydropyridine and Pd/C was found to be an efficient reducing system for the selective reduction of aromatic azides.

关键词： Reduction Hantzsch 1,4-dihydropyridine Pd/C Aromatic azides