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论电子信件的表现形式与价值定位 被引量:1
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作者 李惠娟 《海南广播电视大学学报》 2009年第1期40-43,共4页
电子邮件是在互联网中发展起来的书信形态,与网络写作的多元性、众声喧哗性和非权威性等有诸多相似之处,然而电子邮件时代的信件被大众接受及其写作状态的转变却显得顺利与自然得多。网络使得个体化书信得到了最大的表现平台和绝对自由... 电子邮件是在互联网中发展起来的书信形态,与网络写作的多元性、众声喧哗性和非权威性等有诸多相似之处,然而电子邮件时代的信件被大众接受及其写作状态的转变却显得顺利与自然得多。网络使得个体化书信得到了最大的表现平台和绝对自由的发送的机会和场所。网络信件和传统信件一起构成了时代书信的整体,并且使当代书信书写的传统观念得以改变,同时也揭示了书信形式"多层面"的具体内涵。 展开更多
关键词 电子信件 播散方式 价值导向
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Scholte wave dispersion and particle motion mode in ocean and ocean crust 被引量:1
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作者 Xu Xin Wan Yong-Ge +1 位作者 Li Zhen-Yue Sheng Shu-Zhong 《Applied Geophysics》 SCIE CSCD 2022年第1期132-142,146,共12页
The dispersion equation of the Scholte wave was reviewed using the homogeneous elastic half-space covered by a liquid layer,and the range of the Scholte wave propagation velocity was examined using the dispersion equa... The dispersion equation of the Scholte wave was reviewed using the homogeneous elastic half-space covered by a liquid layer,and the range of the Scholte wave propagation velocity was examined using the dispersion equation.The displacement expressions of the Scholte waves in liquid and solid were derived.Additionally,the mode of motion of Scholte waves in liquid and solid and their variation with depth was studied.The following results were obtained:The dispersion equation shows that the propagation velocity of the fundamental Scholte wave was greater than the P-wave in liquid and less than that of the Scholte wave in homogeneous elastic half-space.In contrast,the velocity of higher-order Scholte waves was greater than that of P waves in liquid and S-waves in solid.Only the fundamental Scholte wave has no cutoff frequency.The Scholte wave at the liquid surface moved only vertically,while the particles inside the liquid medium moved elliptically.The amplitude variation with depth in the solid medium caused the particle motion to change from a retrograde ellipse to a prograde ellipse.The above results imply the study of Scholte waves in the ocean and oceanic crust and help estimate ocean depths. 展开更多
关键词 Scholte waves in the ocean and oceanic crust dispersion equation propagation velocity amplitude mode of motion
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Unknown parameter’s variance-covariance propagation and calculation in generalized nonlinear least squares problem 被引量:6
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作者 陶华学 郭金运 《Journal of Coal Science & Engineering(China)》 2005年第1期52-55,共4页
The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. Th... The unknown parameter’s variance-covariance propagation and calculation in the generalized nonlinear least squares remain to be studied now, which didn’t appear in the internal and external referencing documents. The unknown parameter’s vari- ance-covariance propagation formula, considering the two-power terms, was concluded used to evaluate the accuracy of unknown parameter estimators in the generalized nonlinear least squares problem. It is a new variance-covariance formula and opens up a new way to evaluate the accuracy when processing data which have the multi-source, multi-dimensional, multi-type, multi-time-state, different accuracy and nonlinearity. 展开更多
关键词 generalized nonlinear least squares problem unknown parameter vari- ance-covariance propagation
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