In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called n...In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called no phase slipping adaptive bandwidth（NPS-AB） is proposed, which can adjust the loop bandwidth adaptively for different working conditions. As a result, both the tracking precision and the dynamic performance can be achieved concurrently. NPS-AB has two features to keep the loop stable： one is the capability of quick response to dynamics; the other is a series of additional constraints when the bandwidth is switched. Compared with other methods, there is no phase slipping during the adjustment process for NPS-AB. The phase integer ambiguity can be avoided and the phase value is kept valid. It is meaningful for carrier ranging systems. Simulation results show that NPS-AB can deal with sudden dynamics and keep the pseudo-range value stable in the entire dynamic process.展开更多
The resolution of the multistatic passive radar imaging system(MPRIS)is poor due to the narrow bandwidth of the signal transmitted by illuminators of opportunity.Moreover,the inaccuracies caused by the inaccurate trac...The resolution of the multistatic passive radar imaging system(MPRIS)is poor due to the narrow bandwidth of the signal transmitted by illuminators of opportunity.Moreover,the inaccuracies caused by the inaccurate tracking system or the error position measurement of illuminators or receivers can deteriorate the quality of an image.To improve the performance of an MPRIS,an imaging method based on the tomographic imaging principle is presented.Then the compressed sensing technique is extended to the MPRIS to realize high-resolution imaging.Furthermore,a phase correction technique is developed for compensating for phase errors in an MPRIS.Phase errors can be estimated by iteratively solving an equation that is derived by minimizing the mean recovery error of the reconstructed image based on the principle of fixed-point iteration technique.The technique is nonparametric and can be used to estimate phase errors of any form.The effectiveness and convergence of the technique are confirmed by numerical simulations.展开更多
We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio hi...We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.展开更多
石灰石-石膏湿法烟气脱硫(wet flue gas desulfurization,WFGD)工艺具有吸收剂来源广、成本低、脱硫效率高等优点,成为应用最广泛的烟气脱硫工艺。湿法脱硫过程中,燃煤烟气在喷淋浆液的洗涤作用下不仅能高效脱除SO2而且可以协同去除细...石灰石-石膏湿法烟气脱硫(wet flue gas desulfurization,WFGD)工艺具有吸收剂来源广、成本低、脱硫效率高等优点,成为应用最广泛的烟气脱硫工艺。湿法脱硫过程中,燃煤烟气在喷淋浆液的洗涤作用下不仅能高效脱除SO2而且可以协同去除细颗粒物,但同时存在石灰浆液夹带导致出口颗粒物浓度增加的问题。本文首先综述了湿法脱硫的应用现状,对比了湿法脱硫系统前后细颗粒物物性变化,然后概述了应用于湿法脱硫协同去除细颗粒物的新方法,包括脱硫塔内部结构调整以及促进细颗粒物凝聚长大,同时分析了湿法脱硫工艺中采用荷电细水雾吸附细颗粒物并增益脱除SO2的可行性,以期为燃煤电厂细颗粒物排放控制提供借鉴。最后指出未来湿法脱硫技术不仅要实现高脱硫效率,而且能有效脱除未被静电除尘器脱除的细颗粒物,湿法脱硫技术的发展趋势是多种技术耦合实现多污染物的协同脱除。展开更多
文摘In a system based on the phase lock loop（PLL）, a trade-off must be made between the tracking precision and the dynamic performance if constant parameters are adopted. To overcome this drawback, a new method called no phase slipping adaptive bandwidth（NPS-AB） is proposed, which can adjust the loop bandwidth adaptively for different working conditions. As a result, both the tracking precision and the dynamic performance can be achieved concurrently. NPS-AB has two features to keep the loop stable： one is the capability of quick response to dynamics; the other is a series of additional constraints when the bandwidth is switched. Compared with other methods, there is no phase slipping during the adjustment process for NPS-AB. The phase integer ambiguity can be avoided and the phase value is kept valid. It is meaningful for carrier ranging systems. Simulation results show that NPS-AB can deal with sudden dynamics and keep the pseudo-range value stable in the entire dynamic process.
基金Project supported by the National Natural Science Foundation of China(No.61401526)the Innovative Research Team in University,China(No.IRT0954)the Foundation of National Ministries,China(No.9140A07020614DZ01)
文摘The resolution of the multistatic passive radar imaging system(MPRIS)is poor due to the narrow bandwidth of the signal transmitted by illuminators of opportunity.Moreover,the inaccuracies caused by the inaccurate tracking system or the error position measurement of illuminators or receivers can deteriorate the quality of an image.To improve the performance of an MPRIS,an imaging method based on the tomographic imaging principle is presented.Then the compressed sensing technique is extended to the MPRIS to realize high-resolution imaging.Furthermore,a phase correction technique is developed for compensating for phase errors in an MPRIS.Phase errors can be estimated by iteratively solving an equation that is derived by minimizing the mean recovery error of the reconstructed image based on the principle of fixed-point iteration technique.The technique is nonparametric and can be used to estimate phase errors of any form.The effectiveness and convergence of the technique are confirmed by numerical simulations.
文摘We theoretically investigated laser trimming to adjust grating offset in phase-shifted fiber grating coupler (FGC) for all-optical switching application. It was clarified that the trimming made the extinction ratio higher in all-optical FGC switch.
文摘石灰石-石膏湿法烟气脱硫(wet flue gas desulfurization,WFGD)工艺具有吸收剂来源广、成本低、脱硫效率高等优点,成为应用最广泛的烟气脱硫工艺。湿法脱硫过程中,燃煤烟气在喷淋浆液的洗涤作用下不仅能高效脱除SO2而且可以协同去除细颗粒物,但同时存在石灰浆液夹带导致出口颗粒物浓度增加的问题。本文首先综述了湿法脱硫的应用现状,对比了湿法脱硫系统前后细颗粒物物性变化,然后概述了应用于湿法脱硫协同去除细颗粒物的新方法,包括脱硫塔内部结构调整以及促进细颗粒物凝聚长大,同时分析了湿法脱硫工艺中采用荷电细水雾吸附细颗粒物并增益脱除SO2的可行性,以期为燃煤电厂细颗粒物排放控制提供借鉴。最后指出未来湿法脱硫技术不仅要实现高脱硫效率,而且能有效脱除未被静电除尘器脱除的细颗粒物,湿法脱硫技术的发展趋势是多种技术耦合实现多污染物的协同脱除。
