Rational development and utilization of hilly land is an effective measure for raising land productivity, developing countryside economy, increasing peasants＇ income, conserving soil and water, and improving eco-envi...Rational development and utilization of hilly land is an effective measure for raising land productivity, developing countryside economy, increasing peasants＇ income, conserving soil and water, and improving eco-environment. The growth and root distribution of mulberry trees were studied. Various indexes including soil physical characters and hydrological status, water infiltration rate, water and soil loss and soil erosion amount were tested. The results indicated that mulberry trees had the effects of intercepting rainfall, improving soil infiltration rate, decreasing soil erosion amount, and conserving water and soil展开更多
A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) la...A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.展开更多
基金Supported by Financial Innovation Ability Improving Engineering Project in Sichuan Province(2016TSCY-006)Technological Innovation Fund for Small and Medium Technology-based Enterprises of Nanchong City(15C0009)~~
文摘Rational development and utilization of hilly land is an effective measure for raising land productivity, developing countryside economy, increasing peasants＇ income, conserving soil and water, and improving eco-environment. The growth and root distribution of mulberry trees were studied. Various indexes including soil physical characters and hydrological status, water infiltration rate, water and soil loss and soil erosion amount were tested. The results indicated that mulberry trees had the effects of intercepting rainfall, improving soil infiltration rate, decreasing soil erosion amount, and conserving water and soil
基金supported by the National Natural Science Foundation of China(No.61475015)
文摘A cost-effective ultra-dense wavelength-division-multiplexed passive optical network(UD-WDM PON) with speed of 12.5 Gbit/s and channel spacing of 12.5 GHz is proposed and demonstrated. The distributed feedback(DFB) lasers modulated in 4-level pulse amplitude modulation(4-PAM) format are used for downstream links, and the reflective semiconductor optical amplifiers(RSOAs) together with an optical frequency comb modulated in quadrature phase shift keying(QPSK) format are used for upstream links. We can achieve the error-free transmission of the upstream signals with speed of 12.5 Gbit/s even after 20 km single-mode fiber(SMF). The power penalty obtained by using the frequency comb generator instead of a tunable laser is around 0.5 d B. By using 11 DFB lasers and a set of intensity and phase modulators, it is possible to provide the seed light for 297 optical network units(ONUs) within the C-band.
