排序方式: 共有19条查询结果,搜索用时 15 毫秒
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为了分析冲击荷载作用下粘土的孔隙水压力的增长规律,为分析粘土介质的动态响应、动力固结加固提供理论依据,将冲击瞬态荷载简化为三角形荷载,通过编制瞬变动态弹塑性有限元程序,对冲击荷载作用下粘土孔隙水压的动态响应进行了模拟,得出了冲击荷载作用下粘土孔隙水压的增长规律,发现孔隙水压力峰值无论是随水平距离还是随深度的增加均呈指数形式衰减,和实际工程施工中孔隙水压的监测数据相吻合。 相似文献
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Gongqi Yu Bin XuJinming Xiong Xiangfei LiuLi Liu Songliu Yuan 《Journal of magnetism and magnetic materials》2011,323(15):1925-1928
The effect of Cr doping on magnetic and electrical properties in the bilayer manganites La1.4Sr1.6(Mn1−yCry)2O7 (y=0-0.1) has been investigated. When y≤0.025, Cr doping enhances the three-dimensional magnetic transition temperature TC and the insulator-metal transition temperature TIM as well as decreases the peak resistivity at TIM, and the saturated magnetization decreases slightly. When y≥0.035, TIM decreases gradually accompanied by the increase of peak resistivity, but TC remains nearly constant, and the saturated magnetization decreases heavily. In the whole doping region, the two-dimensional magnetic transition temperature T? monotonously decreases with an increasing of Cr doping level. These results can be explained by considering different magnetic (including ferromagnetic and antiferromagnetic) interactions between Mn ions and Cr ions. 相似文献
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J. Sun G. Yu Y. Jiang S. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(1):83-88
The additivity rule is employed to obtain the total (elastic+inelastic) cross-sections for positron scattering from molecules
including a number of diatomic, polyatomic molecules (H2, N2, HCl, CO2, NH3, SF6, CH4, C2H4 and C3H8) over an incident energy range of 10-1000 eV. The total cross-sections (TCS) of the constituent atoms of molecules are obtained
by employing a complex optical model potential (composed of static, polarization and absorption potential). The present results
are compared with experimental data and other theoretical calculations, good agreement is obtained in intermediate- and high-energy
region.
Received: 11 November 1997 / Revised: 23 March 1998 / Accepted: 16 June 1998 相似文献
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建立了气相色谱-串联质谱同时测定食用油中对苯二甲酸二(2-乙基己基)酯和偏苯三甲酸三(2-乙基己基)酯两种非邻苯二甲酸酯类增塑剂的方法。样品采用乙腈提取,于-20℃冷冻除脂净化,用气相色谱-串联质谱选择反应监测模式测定。两种化合物的检出限为0.03 mg/kg,定量限为0.1 mg/kg,线性范围为0.1~10 mg/kg。3个添加水平(0.1、0.3和1.0 mg/kg)下的回收率为81.04%~108.31%,相对标准偏差为0.70%~9.91%。该方法简便、准确,适用于食用油中对苯二甲酸二(2-乙基己基)酯和偏苯三甲酸三(2-乙基己基)酯的检测。 相似文献
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基于近红外光谱的淡水鱼新鲜度在线检测方法研究 总被引:1,自引:0,他引:1
新鲜度是反映鱼类品质以及可否食用的重要指标,在线检测直接关系到食品质量与安全的实施应用,因此对淡水鱼新鲜度进行在线无损检测具有重要意义。应用近红外光谱对淡水鱼新鲜度进行在线检测,试验装置采用自行搭建的淡水鱼近红外光谱在线采集装置,试验时样品在输送链上以0.5 m·s-1的速度运动,采集其近红外漫反射光谱(900~2 500 nm),并用支持向量机(support vector machine, SVM)建立淡水鱼新鲜度在线检测模型。采用光谱理化值共生距离(sample set partitioning based on joint X-Y distance algorithm, SPXY)算法对样本集进行划分,其中校正集111条(新鲜57条,变质54条)、测试集37条(新鲜19条,变质18条),通过对比不同的光谱预处理方法对预测结果的影响,明确了一阶导结合标准化预处理为最优光谱预处理方法,经过该方法预处理后所建模型对校正集的正确识别率为97.96%,对测试集的识别率为95.92%。为了提高模型运行速度对建模所用光谱变量进行优化,分别采用遗传算法(genetic algorithm, GA)、连续投影算法(successive projection algorithm, SPA)和竞争性自适应重加权算法(competitive adaptive reweighed sampling algorithm, CARS) 三种不同的特征变量选择方法对特征波长进行筛选,通过建模比较分析确定CARS为最优波长选择方法,以所选的10个特征波长建立淡水鱼新鲜度支持向量机检测模型,模型对校正集的正确识别率为100%,对测试集的识别率为93.88%。该研究可为近红外光谱用于淡水鱼新鲜度在线检测提供技术支持。 相似文献
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制导炸弹连续打击下混凝土重力坝的破坏效应 总被引:3,自引:0,他引:3
选取某制导炸弹作为研究对象,利用任意Lagrange-Euler计算方法,通过对大口径、高弹重武器的
侵彻爆炸的全过程三维数值仿真,针对连续打击作用下大坝破坏效应进行了研究。研究表明,侵彻引起的振
动很小,引起质点振动的主要是弹药的爆炸。由于相继打击间隔时间已远超过大坝动态响应时间,相继打击
引起的坝体振动基本上不存在叠加效应。但前枚制导炸弹侵彻爆炸的破坏效应为后继制导炸弹提供了“临空
面”,使得后继制导炸弹无论是侵彻深度还是爆炸破坏范围等破坏效应都有所增大。连续打击下,爆炸后形成
的破坏范围基本上互相连通,对大坝的正常运行及安全构成威胁。 相似文献
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Hu Chi 《International Journal of Infrared and Millimeter Waves》2003,24(11):1999-2006
Semicircular groove guide is a kind of waveguide for millimeter waves. In this paper, a conformal mapping technique is used to analyze it. Several semicircular groove guides are calculated with the method. It is shown that their cutoff wavelength calculated by the method are very close to those calculated by the transverse resonance method. 相似文献