检索结果-南通市图书馆

Effects of post annealing on the microstructure,precipitation behavior,and mechanical property of a(CoCrNi)_(94)Al_(3)Ti_(3)medium-entropy alloy fabricated by laser powder bed fusion

引用

Journal of Materials Science & Technology 2023年第4期135卷 142-155页

作者： Zhuang Li Pengcheng Zhao Tiwen Lu kai Feng Yonggang tong Binhan sun Ning Yao Yu Xie Bolun Han Xiancheng Zhang Shantung Tu Key Laboratory of Pressure Systems and Safety Ministry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China College of Automobile and Mechanical Engineering Changsha University of Science and TechnologyChangsha 410114China

The additive manufacturing of multi-principal element alloys has remarkable potential for industrial *** this study,a(CoCrNi)_(94)Al_(3)Ti_(3)medium-entropy alloy(MEA)with adequate strength-ductility synergy was prepared via laser powder bed *** microstructural evolution,mechanical property,and deformation mechanisms of the MEA were investigated after post annealing for a short period(0.5 h)at a temperature range of 773-1373 K using various microstructural characterization techniques and quantitative *** static recrystallization temperature of the(CoCrNi)_(94)Al_(3)Ti_(3)MEA ranged from 973 to 1073 *** average grain size first decreased and then increased,while the dislocation den-sity persistently decreased and texture gradually weakened with increasing annealing ***-richσ-phase precipitates formed after 1073 K and then gradually dissolved at 1373 K,while Ni,Al,and Ti elements were aggregated to form a small amount of fine L1_(2)coherent precipitates with an aver-age diameter of approximately 70 nm at 1373 *** evolution of the dislocation density,grain size,and precipitates significantly influenced the propensity of deformation twins and stacking faults,which consequently affected the strain hardening behavior and mechanical *** quantitative calcu-lation of strengthening mechanisms showed that dislocation strengthening played a dominant role at annealing temperatures below 1073 K,and it significantly weakened at 1373 *** and grain boundary strengthening both markedly increased owing to the formation of precipitation particles and recrystallization-induced grain refinement after annealing at 1073 K.

关键词： Medium-entropy alloy Additive manufacturing Heat treatment Strengthening mechanism Microstructural evolution

来源：

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

Dynamics Analysis of Water Ditching of Deformable Helicopter

引用

Transactions of Nanjing University of Aeronautics and Astronautics 2017年第6期34卷 720-732页

作者： sun Xuan tong Mingbo Wang Zhengzhong Ministerial Key Discipline Laboratory of Advanced Design Technology of Aircraft Nanjing University of Aeronautics and Astronautics Science and Technology on Rotorcraft Aeromechanics Laboratory China Helicopter Research and Development Institute

To understand the effect of attitude angle on helicopter water ditching,a finite element model(FEM)of helicopter water ditching was established via the nonlinear finite element *** on the LS-DYNA software,the finite element model of the helicopter was *** attitude of helicopter water ditching was simulated and *** pressure measuring points were arranged in the aircraft belly *** pressure curves were provided ***,the effects of attitude on helicopter water ditching was discussed,particularly the stability and the overload of *** the contours of stress,it can be figured out that the maximum pressure locates at the position of aircraft belly where stiffness is *** simulation and experimental results were *** difference of peak acceleration along the Z direction was ***,this method is feasible and helpful for the design of helicopter water ditching.

关键词： water ditching helicopter LS-DYNA SPH method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Positive Solutions for Second-Order m-Point Boundary Value Problems on Time Scales

引用

Acta Mathematica Sinica,English Series 2006年第6期22卷 1797-1804页

作者： Wan tong LI Hong Rui sun School of Mathematics and Statistics Lanzhou University Lanzhou 730000 P. R. China

Let T be a time scale such that 0, T ∈ T. By means of the Schauder fixed point theorem and analysis method, we establish some existence criteria for positive solutions of the m-point boundary value problem on time scales where α ∈ Ctd（（O,T,[0,∞））,f∈ Ckd（[0,∞）×[0,∞））,β,γ ∈[0,∞）,ξi ∈（0,p（T）.b,ai∈ （0,∞）（for i = 1,..., m - 2） are given constants satisfying some suitable hypotheses. We show that this problem has at least one positive solution for sufficiently small b 〉 0 and no solution for sufficiently large b. Our results are new even for the corresponding differential equation （T = R） and difference equation （T = Z）.

关键词： time scales positive solution Schauder fixed point theorem

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Kinematics of Chinese toad Bufo gargarizans

引用

Science China(Technological Sciences) 2010年第11期53卷 2936-2941页

作者： WANG ChaoFei tong Jin sun JiYu Key Laboratory of Engineering Bionics Ministry of EducationJilin UniversityChangchun 130022China College of Biological and Agricultural Engineering Jilin UniversityChangchun 130022China

A three-dimensional motion force tester for animal was used to measure the reaction forces of the feet of a Chinese toad (B. gargarizans) against a horizontal solid surface on which it crawled. The motion behavior of the Chinese toad was recorded by a high-speed camera on line. The motor function of every foot was analyzed. It was found that the lateral force represents the control ability of side-to-side locomotion, controls the lateral movement, and maintains a stable state for the sustainable creeping gesture. The forefeet play the assistant role and the hind feet play the main role in driving. The normal force of the forefeet is significantly greater than that of the hind feet, so the forefeet play the main role in supporting the body and the hind feet play the assistant role. The normal force is significantly greater than the lateral force and the driving force as well. There is little change for the friction force and the support angle of the all four feet. The average value of the support angle is 70°–80°. The Chinese toad’s vola friction coefficient of the forefeet is less than that of the hind feet. The above results indicate that the difference in kinematics and the material characteristic of the contact skin of the Chinese toad. The results could be useful to the structure design and gait optimization of some robots.

关键词： Chinese toad Bufo gargarizans kinematics 3-D motion force

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Novel method of ordinal bearing estimation for more sources based on oblique projector

引用

Journal of Systems Engineering and Electronics 2009年第3期20卷 445-449页

作者： sun Wei Bai Jianlin Wang kai Missile Inst. Air Force Engineering Univ. Sanyuan 713800 P. R. China Aviation Equipment Academy Beijing 100085 P. R. China

A novel direction of arrival （DOA） estimation method is proposed when uncorrelated, correlated, and coherent sources coexist under color noise field. The uncorrelated and correlated sources are firstly estimated using the conventional spatial spectrum estimation method, then the noise and uncorrelated sources in Toeplitz structure are eliminated using differencing, finally by exploiting the property of oblique projection, the contributions of correlated sources are then eliminated from the covariance matrix and only the coherent sources remain. So the coherent sources can be estimated by the technique of modified spatial smoothing. The number of sources resolved by this approach can exceed the number of array elements without repeatedly estimating correlated sources. Simulation results demonstrate the effectiveness and efficiency of our proposed method.

关键词： spatial differencing oblique projector Toeplitz property direction of arrival estimation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Metal-free tetra-n-butylammonium bromide-mediated aerobic oxidative synthesis of β-ketosulfones from styrenes

引用

Science China Chemistry 2017年第3期60卷 353-357页

作者： Xin Wan kai sun Guisheng Zhang College of Chemistry and Chemical Engineering Anyang Normal University School of Chemistry and Chemical Engineering Henan Normal University

An efficient and broadly applicable protocol for the aerobic coupling of styrenes with sulfonylhydrazides has been developed that affords P-ketosulfones bearing various functional groups in moderate to excellent *** preliminary experimental results support the involvement of active benzyl radical species,and a radical pathway was therefore proposed for the reaction.

关键词： styrenes aerobic difunctionalization ketosulfones transition metal-free conditions

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Distance Distribution and Reliability of Small-World Networks

引用

Chinese Physics Letters 2001年第3期18卷 452-454页

作者： sun kai OUYANG Qi Department of Physics and Mesoscopic Physics Laboratory Peking UniversityBeijing 100871

We have studied the distribution of distances in small-world network by computer *** found that in a small world network,the longest distance between two vertices is just slightly longer than the average distance,indicating that the efficiency of the network is absolute rather than in *** also investigated the robustness of a small-world network by randomly cutting some long paths in the *** results show that the network is reliable against random cutting.

关键词： absolute slightly Reliability

来源：

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

Copper-catalyzed arenes amination with saccharins

引用

Science China Chemistry 2015年第8期58卷 1354-1358页

作者： kai sun Yan Li Qian Zhang College of Chemistry and Chemical Engineering Anyang Normal University Department of Chemistry Northeast Normal University

A novel copper-catalyzed direct C–N formation reaction of simple arenes with cheap and pharmacological saccharin derivatives under relatively mild conditions was developed with arenes as limiting *** work provided a ... 详细信息

关键词： aromatic amines C-N bond formation arenes saccharins arenes as limiting reagents

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Laguerre Isopararmetric Hypersurfaces in R^4

引用

Acta Mathematica Sinica,English Series 2012年第6期28卷 1179-1186页

作者： tong Zhu LI Hua Fei sun Department of Mathematics Beijing Institute of Technology

Let x ： M →R^n be an umbilical free hypersurface with non-zero principal curvatures. Then x is associated with a Laguerre metric g, a Laguerre tensor L, a Laguerre form C, and a Laguerre second fundamental form B which are invariants of x under Laguerre transformation group. A hypersurface x is called Laguerre isoparametric if its Laguerre form vanishes and the eigenvalues of B are constant. In this paper, we classify all Laguerre isoparametric hypersurfaces in R^4.

关键词： Laguerre transformation group Laguerre isoparametric hypersurface Laguerre second fundamental form

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Anti-miRNA-221 sensitizes human colorectal carcinoma cells to radiation by upregulating PTEN

引用

World Journal of Gastroenterology 2013年第48期19卷 9307-9317页

作者： Qi Xue kai sun Hai-Jun Deng Shang-tong Lei Jing-Qing Dong Guo-Xin Li Department of General Surgery Nanfang Hospital of Southern Medical University

AIM:To investigate the regulative effect of miRNA(miR)-221 on colorectal carcinoma(CRC)cell radiosensitivity and the underlying ***:A human CRC-derived cell line was cultured conventionally and exposed to different doses of X-rays(0,2,4,6 and 8 Gy).The total RNA and protein of the cells were extracted 24 h after irradiation,and the alteration of miR-221 and phosphatase and tensin homolog deleted on chromosome 10(PTEN)gene mRNA expression was detected by real-time reverse transcriptase polymerase chain reaction(PCR).The protein alteration of PTEN in the cells was detected by Western ***2 cells were pretreated with or without anti-PTEN-siRNA prior to the addition of premiR-221 or anti-miR-221 using Lipofectamine *** formation assay and flow cytometry analysis were used to measure the surviving cell fraction and the sensitizing enhancement ratio after ***-ditionally,PTEN 3′-untranslated region fragment was PCR amplified and inserted into a luciferase reporter *** luciferase reporter plasmid construct was then transfected into CRC cells together with premiR-221 or anti-miR-221,and the luciferase activity in the transfected cells was ***:The X-ray radiation dose had a significant effect on the expression of miR-221 and PTEN protein in human Caco2 cells in a dose-dependent *** miR-221 expression level improved gradually with the increase in irradiation dose,while the PTEN protein expression level reduced ***-221 expression was significantly reduced in the anti-miR-221 group compared with the pre-miR-221 and negative control groups(P<0.01).Anti-miR-221 upregulated expression of PTEN protein and enhanced the radiosensitivity of Caco2 cells(P<0.01).Moreover,the inhibitory effect was dramatically abolished by pretreatment with anti-PTEN-siRNA,suggesting that the enhancement of radiosensitivity was indeed mediated by PTEN.A significant increase of luciferase activity was detected in CRC cells tha

关键词： Colorectal carcinoma miR-221 Phosphatase and tensin homolog deleted on chromosome 10 Radiosensitivity

来源：

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

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

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

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

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：