The measurement of underground medium variation using a repeated artificial source has gradually become an important goal to pursue. In recent years,we have developed and improved a technology system with large capaci...The measurement of underground medium variation using a repeated artificial source has gradually become an important goal to pursue. In recent years,we have developed and improved a technology system with large capacity airguns excited in land reservoirs by transplanting marine seismic exploration technology. The excitation effect has a close relationship to airgun capacity,water environment,and excitation conditions. In view that large capacity airgun must be excited without a water environment,we expand the system to use in downhole. Based on the BHS-2200 LL downhole airgun with a capacity of250in3,this paper carries out a comparative analysis on the characteristics of an airgun source excited in 0. 2m- and 5. 0m-diameter wells,and the results show that:( 1) The dominant frequency of the airgun signal excited in a 5. 0m well is mainly from 10 Hz to40Hz,lower than that in a 0. 2m well,and the larger body of water is good for bubble oscillation.( 2) In terms of exciting energy,the signal excited in a 5. 0m well has stronger energy than in a 0. 2m well,with a difference of 1 order in magnitude,and the signal can be detected up to 9km excited in a 5. 0m well with a single shot.( 3) The airgun signal has good repeatability in both excitation wells. The downhole airgun excitation technology system has potential application in dynamic monitoring near a fault zone with a small scale range, exploration of oil and mineral resources, and modern urban geophysical environment.展开更多
In this paper an attempt has been made to find the aperture field distribution in a rectangular waveguide for non-sinusoidal, periodic excitations using Multiple Cavity Modeling Technique. The excitation functions, co...In this paper an attempt has been made to find the aperture field distribution in a rectangular waveguide for non-sinusoidal, periodic excitations using Multiple Cavity Modeling Technique. The excitation functions, considered, are square, trapezoidal and clipped sine wave in nature. In the present analysis these time domain excitation functions have been represented in terms of a truncated Fourier series consisting of the fundamental frequency and its higher harmonics. Within the waveguide the fundamental frequency will give rise to a dominant mode excitation whereas the higher order modes will excite dominant as higher order modes. If the higher harmonics are assumed suppressed then the waveguide is subjected only to a dominant mode excitation. Results for dominant mode reflection coefficient (magnitude), VSWR and complex transmission coefficient have been computed and compared with theoretical data. The excellent agreement between them validates the analysis.展开更多
The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, ...The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value.展开更多
Language education centers primarily on fostering linguistic skills and language communication skills for students. In the process of teaching Chinese language, it is in the classroom that is the place tofoster studen...Language education centers primarily on fostering linguistic skills and language communication skills for students. In the process of teaching Chinese language, it is in the classroom that is the place tofoster student’s linguistic competence and language communication capacity. Therefore, classroom teaching becomes the main place tofoster the language ability and language communication capacity for students while the extracurricular activities are the place for students to apply the knowledge they have learned in the classroom in to the real world. Conducting a survey to investigate extracurricular activities for Chinese language majors at Thai Nguyen University, School of Foreign Languages, the paper proposes solutions to improve the effectiveness of extracurricular activities for students and create excitement for students in learning.展开更多
为获取运行中的特高压交流输电线路无线电干扰水平及其特性,在特高压交流试验示范工程沿线的湖北枣阳建立了一处电磁环境长期观测站,对历时1 a得到的14.4万组有效数据进行了统计分析,获取了我国特高压交流输电线路无线电干扰的主要特性...为获取运行中的特高压交流输电线路无线电干扰水平及其特性,在特高压交流试验示范工程沿线的湖北枣阳建立了一处电磁环境长期观测站,对历时1 a得到的14.4万组有效数据进行了统计分析,获取了我国特高压交流输电线路无线电干扰的主要特性。研究表明:1 000 kV特高压交流输电线路无线电干扰好天气和雨天的长期测试数据基本符合正态分布,频谱特性和横向分布规律与CISPR研究结果基本一致,得到了无线电干扰不同天气条件下的统计值和累积概率曲线。0.5 MHz无线电干扰全天候80%、95%值分别为55.06、65.37 d B,好天气平均值为48.22 d B。采用CISPR激发函数法计算我国特高压交流单回路无线电干扰时,大雨到好天气下平均值的差值可取中值20.5 d B。展开更多
基金jointly funded by the Natural Science Foundation of China(41204047,41574052)Academician Chen Yong Workstation Project of Yunnan Province
文摘The measurement of underground medium variation using a repeated artificial source has gradually become an important goal to pursue. In recent years,we have developed and improved a technology system with large capacity airguns excited in land reservoirs by transplanting marine seismic exploration technology. The excitation effect has a close relationship to airgun capacity,water environment,and excitation conditions. In view that large capacity airgun must be excited without a water environment,we expand the system to use in downhole. Based on the BHS-2200 LL downhole airgun with a capacity of250in3,this paper carries out a comparative analysis on the characteristics of an airgun source excited in 0. 2m- and 5. 0m-diameter wells,and the results show that:( 1) The dominant frequency of the airgun signal excited in a 5. 0m well is mainly from 10 Hz to40Hz,lower than that in a 0. 2m well,and the larger body of water is good for bubble oscillation.( 2) In terms of exciting energy,the signal excited in a 5. 0m well has stronger energy than in a 0. 2m well,with a difference of 1 order in magnitude,and the signal can be detected up to 9km excited in a 5. 0m well with a single shot.( 3) The airgun signal has good repeatability in both excitation wells. The downhole airgun excitation technology system has potential application in dynamic monitoring near a fault zone with a small scale range, exploration of oil and mineral resources, and modern urban geophysical environment.
文摘In this paper an attempt has been made to find the aperture field distribution in a rectangular waveguide for non-sinusoidal, periodic excitations using Multiple Cavity Modeling Technique. The excitation functions, considered, are square, trapezoidal and clipped sine wave in nature. In the present analysis these time domain excitation functions have been represented in terms of a truncated Fourier series consisting of the fundamental frequency and its higher harmonics. Within the waveguide the fundamental frequency will give rise to a dominant mode excitation whereas the higher order modes will excite dominant as higher order modes. If the higher harmonics are assumed suppressed then the waveguide is subjected only to a dominant mode excitation. Results for dominant mode reflection coefficient (magnitude), VSWR and complex transmission coefficient have been computed and compared with theoretical data. The excellent agreement between them validates the analysis.
基金supported by the Science and Technology Plan of Hunan Province,China(Grant No.2010FJ3148)the National Natural Science Foundation of China(Grant No.11374096)
文摘The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value.
文摘Language education centers primarily on fostering linguistic skills and language communication skills for students. In the process of teaching Chinese language, it is in the classroom that is the place tofoster student’s linguistic competence and language communication capacity. Therefore, classroom teaching becomes the main place tofoster the language ability and language communication capacity for students while the extracurricular activities are the place for students to apply the knowledge they have learned in the classroom in to the real world. Conducting a survey to investigate extracurricular activities for Chinese language majors at Thai Nguyen University, School of Foreign Languages, the paper proposes solutions to improve the effectiveness of extracurricular activities for students and create excitement for students in learning.
文摘为获取运行中的特高压交流输电线路无线电干扰水平及其特性,在特高压交流试验示范工程沿线的湖北枣阳建立了一处电磁环境长期观测站,对历时1 a得到的14.4万组有效数据进行了统计分析,获取了我国特高压交流输电线路无线电干扰的主要特性。研究表明:1 000 kV特高压交流输电线路无线电干扰好天气和雨天的长期测试数据基本符合正态分布,频谱特性和横向分布规律与CISPR研究结果基本一致,得到了无线电干扰不同天气条件下的统计值和累积概率曲线。0.5 MHz无线电干扰全天候80%、95%值分别为55.06、65.37 d B,好天气平均值为48.22 d B。采用CISPR激发函数法计算我国特高压交流单回路无线电干扰时,大雨到好天气下平均值的差值可取中值20.5 d B。
