The influence of the wavelength dispersion on the temperature accuracy of the Raman distributed temperature sensor system （RDTS） is analyzed in detail, and a simple correction algorithm is proposed to compensate the...The influence of the wavelength dispersion on the temperature accuracy of the Raman distributed temperature sensor system （RDTS） is analyzed in detail, and a simple correction algorithm is proposed to compensate the fiber position error caused by the wavelength dispersion. The principle of the proposed algorithm is described theoretically, and the correction on each point along the entire fiber is realized. Temperature simulation results validate that the temperature distortion is corrected and the temperature accuracy is effectively improved from ＋5 ℃ to ±1 ℃.展开更多
It is still argued whether we measure phase or group velocities using acoustic logging tools. In this paper, three kinds of models are used to investigate this problem by theoretical analyses and numerical simulations...It is still argued whether we measure phase or group velocities using acoustic logging tools. In this paper, three kinds of models are used to investigate this problem by theoretical analyses and numerical simulations. First, we use the plane-wave superposition model containing two plane waves with different velocities and able to change the values of phase velocity and group velocity. The numerical results show that whether phase velocity is higher or lower than group velocity, using the slowness-time coherence （STC） method we can only get phase velocities. Second, according to the results of the dispersion analysis and branch-cut integration, in a rigid boundary borehole model the results of dispersion curves and the waveforms of the first-order mode show that the velocities obtained by the STC method are phase velocities while group velocities obtained by arrival time picking. Finally, dipole logging in a slow formation model is investigated using dispersion analysis and real-axis integration. The results of dispersion curves and full wave trains show similar conclusions as the borehole model with rigid boundary conditions.展开更多
在研究0.14 THz折叠波导行波管中,提出一种三段相速跳变的设计,使得电子能够在输出段与行波场发生速度再同步,从而提高了电子工作效率。根据色散公式,找到一种影响相速变化的结构因素。通过优化设计进行大信号程序计算,在电压14.95 k V...在研究0.14 THz折叠波导行波管中,提出一种三段相速跳变的设计,使得电子能够在输出段与行波场发生速度再同步,从而提高了电子工作效率。根据色散公式,找到一种影响相速变化的结构因素。通过优化设计进行大信号程序计算,在电压14.95 k V、工作电流30 m A时,与未采用相速变化的结构相比,140 GHz时功率提高了0.84 W,效率提高了9.13%;在142 GHz时功率提高了0.88 W,效率提高了10.4%;-1 d B带宽由原来的5 GHz提高到7 GHz,扩展了行波管的带宽,提高了电子与波的互作用效率。展开更多
In common sense,the chemical reaction between Cu2+ and S2-ions produces black precipitation of CuS.However,if they are separated by an eggshell,they produce copper with trace amount of CuS on the surface of the eggshe...In common sense,the chemical reaction between Cu2+ and S2-ions produces black precipitation of CuS.However,if they are separated by an eggshell,they produce copper with trace amount of CuS on the surface of the eggshell at the side of copper chloride solution within one week.Such an unexpected phenomenon strongly indicated that Cu2+ is able to be reduced into metal copper when S2-diffuses throughout the porous eggshell.The produced copper was verified by reacting with nitric acid to generate red-brown nitrogen dioxide at ambient temperature,as well as by the powder X-ray diffraction(XRD) and energy dispersive analysis of X-rays(EDS).展开更多
基金This work was supported by Natural Science Foundation of China （60977058）, Science Fund for Distinguished Young Scholars of Shandong Province of China （JQ200819）, Independent Innovation Foundation of Shandong University （IIFSDU2010JC002＆2012JC015）, and promotive research fund for excellent young and middle-aged scientists of Shandong Province （BS2010DX028）.
文摘The influence of the wavelength dispersion on the temperature accuracy of the Raman distributed temperature sensor system （RDTS） is analyzed in detail, and a simple correction algorithm is proposed to compensate the fiber position error caused by the wavelength dispersion. The principle of the proposed algorithm is described theoretically, and the correction on each point along the entire fiber is realized. Temperature simulation results validate that the temperature distortion is corrected and the temperature accuracy is effectively improved from ＋5 ℃ to ±1 ℃.
基金supported by the National Natural Science Foundation of China (Grant No. 40774099, 10874202 and 11134011)National 863 Program of China (Grant No. 2008AA06Z205)
文摘It is still argued whether we measure phase or group velocities using acoustic logging tools. In this paper, three kinds of models are used to investigate this problem by theoretical analyses and numerical simulations. First, we use the plane-wave superposition model containing two plane waves with different velocities and able to change the values of phase velocity and group velocity. The numerical results show that whether phase velocity is higher or lower than group velocity, using the slowness-time coherence （STC） method we can only get phase velocities. Second, according to the results of the dispersion analysis and branch-cut integration, in a rigid boundary borehole model the results of dispersion curves and the waveforms of the first-order mode show that the velocities obtained by the STC method are phase velocities while group velocities obtained by arrival time picking. Finally, dipole logging in a slow formation model is investigated using dispersion analysis and real-axis integration. The results of dispersion curves and full wave trains show similar conclusions as the borehole model with rigid boundary conditions.
文摘在研究0.14 THz折叠波导行波管中,提出一种三段相速跳变的设计,使得电子能够在输出段与行波场发生速度再同步,从而提高了电子工作效率。根据色散公式,找到一种影响相速变化的结构因素。通过优化设计进行大信号程序计算,在电压14.95 k V、工作电流30 m A时,与未采用相速变化的结构相比,140 GHz时功率提高了0.84 W,效率提高了9.13%;在142 GHz时功率提高了0.88 W,效率提高了10.4%;-1 d B带宽由原来的5 GHz提高到7 GHz,扩展了行波管的带宽,提高了电子与波的互作用效率。
基金supported by the National Natural Science Foundation of China (20773109)
文摘In common sense,the chemical reaction between Cu2+ and S2-ions produces black precipitation of CuS.However,if they are separated by an eggshell,they produce copper with trace amount of CuS on the surface of the eggshell at the side of copper chloride solution within one week.Such an unexpected phenomenon strongly indicated that Cu2+ is able to be reduced into metal copper when S2-diffuses throughout the porous eggshell.The produced copper was verified by reacting with nitric acid to generate red-brown nitrogen dioxide at ambient temperature,as well as by the powder X-ray diffraction(XRD) and energy dispersive analysis of X-rays(EDS).
基金Supported in part by the the Ministerio de Ciencia e Innovación(FPA2011-25948)the Ministerio de Econom'ia y Competitividad(CICYT-FEDER-FPA 2014-55613-P,SEV-2012-0234)+1 种基金the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya(2014SGR 1450)the Spanish ConsoliderIngenio 2010Programme CPAN(CSD2007-00042)
