The effects of optical losses oil a directly-modulated radio-over-fiber （RoF） system used for distributed antenna networks are determined. The results show that with a properly designed bidirectional amplifier, the ...The effects of optical losses oil a directly-modulated radio-over-fiber （RoF） system used for distributed antenna networks are determined. The results show that with a properly designed bidirectional amplifier, the RoF link can tolerate over 20 and 16 dB of optical losses for down- and up-links, respectively. Simulation results are also consistent with the experimental data. These findings can contribute to tile design of RoF distributed antenna systems with different topologies.展开更多
The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appro...The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appropriate medium in rectangular holes can enhance transmission. The NRI and frequency bandwidth of NRI decrease with increased relative permittivity of the filling medium. A stronger magnetic response that contributes to the dual NRI metamaterials is found.展开更多
The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated usin...The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated using the transfer matrix method.On the basis of the theoretical simulation,we determine that the quality of the resonant transmission peak of this epitaxially grown FPF （EG-FPF） deteriorates through splitting when the substrate is taken into account.Rapid periodic oscillation of peak-transmittivity along with the alteration of substrate thickness is also observed in the simulation results.Finally,a remarkably improved transmission performance of the EG-FPF is obtained by thinning the substrate down to a suitable thickness range through well-controlled grinding and polishing.展开更多
More and more oilfields are using acoustic technology to enhance oil recovery.In order to know the mechanism of acoustic oil recovery technology,the sound radiator of a new downhole vibration device is modeled and ana...More and more oilfields are using acoustic technology to enhance oil recovery.In order to know the mechanism of acoustic oil recovery technology,the sound radiator of a new downhole vibration device is modeled and analyzed.Based on the theoretical background,this paper firstly analyzes the acoustic mechanism for the oil reservoir and then makes a acoustic response analysis on the sound radiator model for frequency and time-domain investigation by using professional acoustic simulation softwareeLMS Virtual.lab Acoustics,finally calculates the acoustic transmission loss in the downhole oil reservoir.The research reveals that firstly,acoustic waves have influences on the oil&water fluidity in the oil reservoir,the oil pressure gradient and the interfacial tension of capillary;secondly,the acoustic radiation power and sound pressure of field point attain a peak on the natural frequency of the sound radiator;thirdly,with the acoustic impact,the sound pressure of oil reservoir would fluctuate so as to improve the oil recovery ratio;the last but not the least one is both the sound pressure of oil reservoir point and the transmission loss of rock have a positive correlation with the vibration frequency.Therefore,it is of great importance for the research of vibration frequency and structure optimization of sound radiator.展开更多
基金supported by the National "863" Program of China(No.2011AA010306)the National "973" Program of China(No.2012CB315705)+2 种基金the National Natural Science Foundation of China(Nos.61107058,61120106001,60932004,61001121,and 60837004)the Beijing Excellent Doctoral Thesis Project(No.YB20101001301)the Cooperation Project between Province and Ministries(No.2011A090200025)
文摘The effects of optical losses oil a directly-modulated radio-over-fiber （RoF） system used for distributed antenna networks are determined. The results show that with a properly designed bidirectional amplifier, the RoF link can tolerate over 20 and 16 dB of optical losses for down- and up-links, respectively. Simulation results are also consistent with the experimental data. These findings can contribute to tile design of RoF distributed antenna systems with different topologies.
基金supported by the National Natural Science Foundation of China(No.60778041)the Graduate Education Innovation Project of Jiangsu Province(No.CXLX13_39)
文摘The transmission and negative refractive index(NRI) of metal–dielectric–metal sandwiched metamaterials perforated with di?erent filling media of holes are numerically studied. Results indicate that filling the appropriate medium in rectangular holes can enhance transmission. The NRI and frequency bandwidth of NRI decrease with increased relative permittivity of the filling medium. A stronger magnetic response that contributes to the dual NRI metamaterials is found.
基金supported by the National "973" Program of China (No. 2010CB327600)the National "863" Program of China (No. 2007AA03Z418)+3 种基金the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0609)the Fundamental Research Funds for the Central University (No. BUPT2011RC0403)the National Natural Science Foundation of China (No. 61020106007)the "111" Project of China (No. B07005)
文摘The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated using the transfer matrix method.On the basis of the theoretical simulation,we determine that the quality of the resonant transmission peak of this epitaxially grown FPF （EG-FPF） deteriorates through splitting when the substrate is taken into account.Rapid periodic oscillation of peak-transmittivity along with the alteration of substrate thickness is also observed in the simulation results.Finally,a remarkably improved transmission performance of the EG-FPF is obtained by thinning the substrate down to a suitable thickness range through well-controlled grinding and polishing.
基金Fund Project:The Graduate Fund of Southwest Petroleum University(CX2014SY02).
文摘More and more oilfields are using acoustic technology to enhance oil recovery.In order to know the mechanism of acoustic oil recovery technology,the sound radiator of a new downhole vibration device is modeled and analyzed.Based on the theoretical background,this paper firstly analyzes the acoustic mechanism for the oil reservoir and then makes a acoustic response analysis on the sound radiator model for frequency and time-domain investigation by using professional acoustic simulation softwareeLMS Virtual.lab Acoustics,finally calculates the acoustic transmission loss in the downhole oil reservoir.The research reveals that firstly,acoustic waves have influences on the oil&water fluidity in the oil reservoir,the oil pressure gradient and the interfacial tension of capillary;secondly,the acoustic radiation power and sound pressure of field point attain a peak on the natural frequency of the sound radiator;thirdly,with the acoustic impact,the sound pressure of oil reservoir would fluctuate so as to improve the oil recovery ratio;the last but not the least one is both the sound pressure of oil reservoir point and the transmission loss of rock have a positive correlation with the vibration frequency.Therefore,it is of great importance for the research of vibration frequency and structure optimization of sound radiator.
