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Mechanical Evaluation of AZ80 Magnesium Alloy in Cast Wrought Form
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作者 Peilin Ying Anita Hu +1 位作者 Wutian Shen Henry Hu 《Journal of Materials Science and Chemical Engineering》 2024年第4期119-125,共7页
Wrought magnesium alloy AZ80 with a thick section of 20 mm was prepared by squeeze casting (SC) and permanent steel mold casting (PSMC). The porosity measurements of the SC and PSMC depicted that SC AZ80 had a pore co... Wrought magnesium alloy AZ80 with a thick section of 20 mm was prepared by squeeze casting (SC) and permanent steel mold casting (PSMC). The porosity measurements of the SC and PSMC depicted that SC AZ80 had a pore content of 0.52%, which was 77% lower than 2.21% of PSMC AZ80 counterpart. The YS, UTS, e<sub>f</sub>, E and strengthening rate of cast AZ80 were determined by mechanical pulling. The engineering stress versus strain bended lines showed that SC AZ80 had a YS of 84.7 MPa, a UTS of 168.2 MPa, 5.1% in e<sub>f</sub>, and 25.1 GPa in modulus. But, the YS, UTS and e<sub>f</sub> of the PSMC AZ80 specimen were only 71.6 MPa, 109.0 MPa, 1.9% and 21.9 GPa. The findings of the mechanical pulling evidently depicted that the YS, UTS, e<sub>f</sub> and E of SC AZ80 were 18%, 54%, 174% and 15% higher than PSMC counterpart. The computed resilience and toughness suggested that the SC AZ80 exhibited greater resistance to tensile loads during elastic deformation and possessed higher capacity to absorb energy during plastic deformation compared to the PSMC AZ80. At the beginning of permanent change, the strengthening rate of SC AZ80 was 10,341 MPa, which was 9% greater than 9489 MPa of PSMC AZ80. The high mechanical characteristics of SC AZ80 should be primarily attributed to its low porosity level. . 展开更多
关键词 Squeeze Casting Wrought Magnesium Alloy AZ80 POROSITY Tensile Prop-erties
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Explanation of Ball Lightning by Plasma Oscillations
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作者 Auguste Meessen 《Journal of Modern Physics》 2023年第11期1355-1381,共27页
Ball Lightning (BL) is a “plasma bubble” that has very remarkable properties. Its membrane contains a higher density of charged particles than the ambient medium. They are held together by mutually attracting surfac... Ball Lightning (BL) is a “plasma bubble” that has very remarkable properties. Its membrane contains a higher density of charged particles than the ambient medium. They are held together by mutually attracting surface charges, generated by collective oscillations of all unbound electrons inside the membrane. Energy losses by collisions and emission of radiation, as well as losses of charged particles by recombination, are compensated by extracting other ones from atmospheric air. Since that occurs in a special rhythmic way, this leads to “parametric amplification” of the oscillations of all unbound electrons in the plasma membrane. Moreover, BL is attracted by higher concentrations of charged particles in atmospheric air. Too much of them leads to explosion and too few to extinction of visible BL. Since the electric charge of BL is oscillating, it is also attracted by metals, water and glass. It can then heat, melt and vaporize these materials without stored energy. BL is even able to pass through window panes in 3 different ways, but that can also be explained. 展开更多
关键词 Ball Lightning Electronic Plasma Oscillations Parametric Amplification Prop-erties of Ball Lightning
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关于矩阵方程AX+YB=C反问题的极小Frobenius范数对称解 被引量:2
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作者 李杰红 赵华敏 《天津科技大学学报》 CAS 2006年第3期63-65,69,共4页
在线性约束下矩阵束最佳逼近问题中,对给定的条件做一改变,解决了一个矩阵束最佳逼近问题。设A、B、C都是m×n阶矩阵,当A和B满足同时奇异值分解(SSVD)时,解决了一个关于X,Y的矩阵方程AX+YB=C的反问题:即求X∈SRn×n,Y∈SRm×... 在线性约束下矩阵束最佳逼近问题中,对给定的条件做一改变,解决了一个矩阵束最佳逼近问题。设A、B、C都是m×n阶矩阵,当A和B满足同时奇异值分解(SSVD)时,解决了一个关于X,Y的矩阵方程AX+YB=C的反问题:即求X∈SRn×n,Y∈SRm×m,使得满足||AX+YB-C||F=min,得到了其Frobenius范数对称解。 展开更多
关键词 反问题 奇异值分解 FROBENIUS范数 对称解
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良性对称性脂肪瘤病 被引量:1
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作者 樊华 李敏 +3 位作者 覃泰杰 瞿申红 叶林松 李凤提 《中国耳鼻咽喉头颈外科》 CSCD 2017年第8期425-426,共2页
1.1临床资料。2012年11月-2016年8月广西壮族自治区人民医院耳鼻咽喉科颈部脂肪瘤患者9例,年龄43-67岁,均为中老年男性,病史为10个月-30年不等。9例患者病变区均无疼痛、压痛,无呼吸困难、吞咽困难,无咽喉疼痛,无声音嘶哑,无咳嗽、咳痰... 1.1临床资料。2012年11月-2016年8月广西壮族自治区人民医院耳鼻咽喉科颈部脂肪瘤患者9例,年龄43-67岁,均为中老年男性,病史为10个月-30年不等。9例患者病变区均无疼痛、压痛,无呼吸困难、吞咽困难,无咽喉疼痛,无声音嘶哑,无咳嗽、咳痰。查体:肿物大小约4 cm×4.5 cm×6 cm-18 cm×12 cm×9 cm,质软,表面光滑,无红肿、破溃,包绕颈部,上至下颌骨,下达甲状软骨, 展开更多
关键词 脂肪瘤样病 多发性对称性(Lipomatosis Multiple symetrical) 外科手术(Surgical Procedures Operative)
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基于最小离差准则的自适应滤波器设计 被引量:1
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作者 郑慧民 谢丹 +1 位作者 杨扬 林品兴 《信号处理》 CSCD 1998年第1期43-46,42,共5页
实际系统中存在大量的具有脉冲性质的非高斯噪声,本文介绍利用实数维低阶矩理论,根据最小离差准则设计自适应滤波器,去除一类服从稳定分布的噪声,并给出了基于LMAD算法的自适应滤波器.实验表明,这种滤波器去除SaS分布噪声的性能... 实际系统中存在大量的具有脉冲性质的非高斯噪声,本文介绍利用实数维低阶矩理论,根据最小离差准则设计自适应滤波器,去除一类服从稳定分布的噪声,并给出了基于LMAD算法的自适应滤波器.实验表明,这种滤波器去除SaS分布噪声的性能比基于LMS算法的滤波器优越。 展开更多
关键词 最小绝对误差 自适应滤波器 设计
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完全图的路分解与因子对称群 被引量:1
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作者 曾伟 《华东交通大学学报》 2007年第5期151-152,共2页
F.Harary在[1]中提出如下一个未解决问题:那些有限置换群是完全图同构分解的因子对称群?本文证明了偶数阶完全图的路分解的因子对称群是循环群.
关键词 完全图 对称群 因子分解
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数控单点金刚石切削非轴对称光学镜面
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作者 任要正 廖月明 +1 位作者 朱派龙 孙伟 《北京理工大学学报》 EI CAS CSCD 1998年第1期119-124,共6页
目的切削加工非轴对称光学镜面.方法用压电陶瓷微位移伺服刀架作执行机构,以金刚石为切削刀具,在自行设计的微机控制加工系统上进行单点切削加工实验.工件材料为黄铜,所加工的曲面满足光学成像系统中的像差补偿反射镜面(非轴对称... 目的切削加工非轴对称光学镜面.方法用压电陶瓷微位移伺服刀架作执行机构,以金刚石为切削刀具,在自行设计的微机控制加工系统上进行单点切削加工实验.工件材料为黄铜,所加工的曲面满足光学成像系统中的像差补偿反射镜面(非轴对称光学镜面)——Zernike方程.结果在工件端面上实现了满足Zernike面形方程的光学反射镜面加工,面形精确度为71.6%.结论用数控单点金刚石切削法加工非轴对称光学镜面可行,所设计的控制加工软硬件系统具有极大的柔性,可靠性较高. 展开更多
关键词 非轴对称 光学镜面 数控加工 单点金刚石切削
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关于局部对称空间中子流形的截面曲率的Pinching问题 被引量:1
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作者 宣满友 《绍兴文理学院学报(哲学社会科学版)》 2000年第6期1-5,53,共6页
讨论了局部对称空间N^n+p中具有平行平均曲率向量的紧致子流形M^n,得到了这类子流形的截面曲率的一个拼挤定理,纠正和推广了[1]中的结论。
关键词 局部对称空间 平行平均曲率向量 全脐点超曲面 子流形 截面曲率 PinChing问题
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多元正态分布与椭球等高对称分布有关概率的计算
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作者 王丽燕 《辽宁师范大学学报(自然科学版)》 CAS 1998年第3期205-208,共4页
得到遵从多元正态分布和遵从椭球等高对称分布的随机向量在n维空间Rn中的第一象限的概率积分值相等.
关键词 多元正态分布 椭球 等高对称分布 概率积分值
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关于Sym(S)=Aut(S)的半群的性质
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作者 张敏 《吉林师范大学学报(自然科学版)》 2004年第4期34-35,共2页
本文通过两个引理,讨论了具有Sym(S)=Aut(S)条件的半群的若干性质.
关键词 半群 引理 性质 条件
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关于局部对称空间中具有平行平均曲率向量的子流形
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作者 宣满友 《绍兴文理学院学报》 2001年第7期19-23,共5页
研究局部对称空间中具有平行平均曲率向量的紧致等距浸入子流形,推广了局部对称空间中极小子流形的一个分类结果.
关键词 局部对称空间 平行平均曲率向量 全测地子流形
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Fuzzy集合的差运算和对称差运算
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作者 郑亚林 张文修 《聊城师院学报(自然科学版)》 1998年第2期5-10,共6页
定义了Fuzzy集合的点式差运算和对称差运算以及格论的差运算和对称差运算,讨论其基本性质,证明两种差运算都拥有deMorgan对偶律.
关键词 点式差运算 差运算 对称差运算 模糊集合 格论
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一类实对称矩阵反问题的最小二乘解
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作者 张宗标 《西昌学院学报(自然科学版)》 2011年第2期21-22,37,共3页
本文讨论一类实对称矩阵反问题及其最佳逼近。通过这类矩阵的一些性质给出了反问题解存在的条件和解的一般表达式,不仅证明了最小二乘解的存在唯一性,而且给出了这个解的具体表达式。
关键词 对称矩阵 最小二乘解 反问题 最佳逼近
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RIGIDITY OF COMPACT MINIMAL SUBMANIFOLDS IN A LOCALLY SYMMETRIC AND CONFORMALLY FLAT RIEMANN MANIFOLD 被引量:4
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作者 陈广华 徐森林 《Acta Mathematica Scientia》 SCIE CSCD 1996年第1期89-97,共9页
The compact minimal submanifold in a locally symetric and conformally flat Riemann manifold is discussed in this paper.We get the Pinching constant for scalar curvature.The result of Li[2]is generallied,but the method... The compact minimal submanifold in a locally symetric and conformally flat Riemann manifold is discussed in this paper.We get the Pinching constant for scalar curvature.The result of Li[2]is generallied,but the method is completely different. Meanwhile,we get better conclusion than that of [3].We also research the Pinching problem for sectional curvature on compact minimal submanifolds in a unit sphere, partially improving the results of S.T.Yan[4]. 展开更多
关键词 Locally symetric conformally flat minimal submanifold scalar curvature sectional curvature.
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REVIEW AND PROSPECT OF HIGH STRENGTH LOW ALLOY TRIP STEEL 被引量:13
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作者 L.Li P.Wollants +3 位作者 Y.L.He B.C.DeCooman X.C.Wei Z.Y.Xu 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2003年第6期457-465,共9页
Research status of high strength low alloy TRIP (transformation induced plasticity) steels for automobile structural parts is briefly described. Composition and microstruc-ture factors especially the morphology, size ... Research status of high strength low alloy TRIP (transformation induced plasticity) steels for automobile structural parts is briefly described. Composition and microstruc-ture factors especially the morphology, size and volume fraction of retained austenite, which largely influence the strength and ductility of the steel, are reviewed and discussed one after another. Modelling of the inter-critical annealing and martempering processes as well as the designing of the TRIP steel aided by commercial software are introduced. Some special aspects of the dynamic mechanical properties of TRIP steel are firstly reported. 展开更多
关键词 HSLA TRIP steel retained austenite dynamic mechanical prop-erty THERMODYNAMICS KINETICS
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基于微多普勒特性的旋转对称进动目标的ISAR干扰技术 被引量:2
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作者 李征 王超 袁乃昌 《航天电子对抗》 2017年第4期46-50,共5页
从旋转对称进动目标运动特性出发,给出了一种生成逆合成孔径雷达(ISAR)欺骗式干扰信号的新方法。干扰机根据这种旋转对称进动目标模型实时计算目标的微动量和强散射点的RCS,并依次对接收到的雷达信号在频率域进行调制转发,生成具有微多... 从旋转对称进动目标运动特性出发,给出了一种生成逆合成孔径雷达(ISAR)欺骗式干扰信号的新方法。干扰机根据这种旋转对称进动目标模型实时计算目标的微动量和强散射点的RCS,并依次对接收到的雷达信号在频率域进行调制转发,生成具有微多普勒特征的虚假目标,实现对敌方雷达系统的欺骗干扰。根据旋转进动目标模型,实时计算干扰机和虚假目标的位置,产生具有真实运动轨迹平面虚假目标,从而实现对基于轨迹平面识别真假目标雷达的有效对抗。仿真结果表明,该方法能够逼真地生成ISAR欺骗式干扰信号。 展开更多
关键词 空中进动目标 微多普勒特性 ISAR RCS
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Direct evidence of high temperature superconductivity in one-unit-cell FeSe films on SrTiO_3 substrate by transport and magnetization measurements 被引量:2
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作者 邢颖 王健 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第11期15-22,共8页
Zero resistance and Meissner effect are two crucial experimental evidences of superconductivity in determining a new kind of superconductor, which can be detected by transport and diamagnetic measurements. In this pap... Zero resistance and Meissner effect are two crucial experimental evidences of superconductivity in determining a new kind of superconductor, which can be detected by transport and diamagnetic measurements. In this paper, we briefly review the main transport and magnetization results on the one unit cell (1-UC) FeSe films grown on SrTiO3 (STO) substrates from our team in recent years, which identify the high temperature superconductivity in 1-UC FeSe films. 展开更多
关键词 two-dimensional superconductivity one-unit-cell FeSe transport measurement diamagnetic prop-erty
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Investigation of mechanical properties of twin gold crystal nanowires under uniaxial load by molecular dynamics method 被引量:1
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作者 张国伟 杨在林 罗刚 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第8期279-283,共5页
Twin gold crystal nanowires, whose loading direction is parallel to the twin boundary orientation, are simulated.We calculate the nanowires under tensile or compressive loads, different length nanowires, and different... Twin gold crystal nanowires, whose loading direction is parallel to the twin boundary orientation, are simulated.We calculate the nanowires under tensile or compressive loads, different length nanowires, and different twin boundary nanowires respectively. The Young modulus of nanowires under compressive load is about twice that under tensile load.The compressive properties of twin gold nanowires are superior to their tensile properties. For different length nanowires,there is a critical value of length with respect to the mechanical properties. When the length of nanowire is greater than the critical value, its mechanical properties are sensitive to length. The twin boundary spacing hardly affects the mechanical properties. 展开更多
关键词 molecular dynamics twinned crystal boundary gold nanowires uniaxial load mechanical prop-erties
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二阶矩随机Hilbert边值问题
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作者 姚村 林峰 《华侨大学学报(自然科学版)》 CAS 北大核心 2011年第6期714-717,共4页
通过对称扩张的方法,把二阶矩随机Hilbert边值问题转化为二阶矩随机Riemann边值问题,最终求解二阶矩随机Hilbert边值问题.
关键词 边值问题 Hilbert问题 RIEMANN问题 二阶矩 对称扩张 随机过程
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Synthesis of nano crystalline spatulae of lead zirconate titanate (PbZr0.52Ti0.48O3) 被引量:1
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作者 S. S. Bhatt S. C. Chaudhry +1 位作者 Neeraj Sharma Sonia Gupta 《Natural Science》 2010年第1期12-17,共6页
A simple and effective method for the synthesis of nano-crystalline PZT spatulae has been re-ported near MPB via a new Solution-Ignition Synthesis route and has been characterized by FT-IR, XRD, TG/DTG/DTA and SEM tec... A simple and effective method for the synthesis of nano-crystalline PZT spatulae has been re-ported near MPB via a new Solution-Ignition Synthesis route and has been characterized by FT-IR, XRD, TG/DTG/DTA and SEM techniques. X-ray line broadening and Scherrer formula show crystallite size to be^20 nm. Densities of nano-crystalline spatulae of PZT in pellet form made by using 2% PVA and without PVA have been found to be 5.35 and 7.51 gm/cm3 respec-tively compared to the theoretical value of 7.78 gm/cm3. Dielectric constants of 83 and 227 of these spatulae with dielectric loss 0.118 and 0.0609 at 1 MHz and a high resistivity value of 3.043 * 107 Ω cm for PZT pellets made without PVA suggest these nano-crystalline PZT spatu-lae to be the potential candidates for high fre-quency applications. 展开更多
关键词 NANOSTRUCTURES Chemical Synthesis INFRARED Spectroscopy X-RAY DIFFRACTION DIELECTRIC Prop-erties
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