A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedu...A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedure.Itis found that there are three different typies of stochastic resonance in the model:the conventional form of stochasticresonance,the stochastic resonance in the broad sense,and the bona fide SR.展开更多
A novel method to partially compensate sigma-delta shaped noise is proposed. By injecting the compensation current into the passive loop filter during the delay time of the phase frequency detector（PFD）,a maximum re...A novel method to partially compensate sigma-delta shaped noise is proposed. By injecting the compensation current into the passive loop filter during the delay time of the phase frequency detector（PFD）,a maximum reduction of the phase noise by about 16dB can be achieved. Compared to other compensation methods,the technique proposed here is relatively simple and easy to implement. Key building blocks for realizing the noise cancellation,including the delay variable PFD and compensation current source, are specially designed. Both the behavior level and circuit level simulation results are presented.展开更多
Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both ...Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both operation modes.The interior flow-borne noise and structure modal were verified through experiments.The flow-borne noise was calculated by the acoustic boundary element method(ABEM),and the flow-induced structure noise was obtained by the coupled acoustic boundary element method(ABEM)/structure finite element method(SFEM).The results show that in pump mode,the pressure fluctuation in the volute is comparable to that in the outlet pipe,but in turbine mode,the pressure fluctuation in the impeller is comparable to that in the draft tube.The main frequency of interior flow-borne noise lies at blade passing frequency(BPF)and it shifts to the 9th BPF for interior flow-induced structure noise.The peak values at horizontal plane appear at the 5th BPF,and at axial plane,they get the highest sound pressure level(SPL)at the 8th BPF.Comparing with interior noise,the SPL of exterior flow-induced structure noise is incredibly small.At the 5th BPF,the pump body,cover and suspension show higher SPL in both modes.The outer walls of turbine generate relatively larger SPL than those of the pump.展开更多
A two-dimensional single-mode laser model with cross-correlation between the real and imaginary parts of the colored quadric pump noise is investigated. A novel laser amplitude Langevin equation is obtained, in which ...A two-dimensional single-mode laser model with cross-correlation between the real and imaginary parts of the colored quadric pump noise is investigated. A novel laser amplitude Langevin equation is obtained, in which the cross-correlation λp between the real and imaginary parts of the pump noise appears. The mean, variance, and skewness of first-passage-time are calculated. It is shown that the mean, variance, and skewness of first-passage-time are strongly affected by λp.展开更多
Pressure ratio is one of the important parameters for evaluating a thermoacoustic heat en- gine. A so-called acoustical pump, which is capable of significantly increasing pressure ratio of a ther- moacoustic heat engi...Pressure ratio is one of the important parameters for evaluating a thermoacoustic heat en- gine. A so-called acoustical pump, which is capable of significantly increasing pressure ratio of a ther- moacoustic heat engine, is proposed. Its operating principle is given. Also, a verification experiment is done with nitrogen gas in the energy-focused ther- moacoustic heat engine, showing that the pressure ratio increased from 1.25 to 1.47.展开更多
Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled ...Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.展开更多
After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerica...After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others'.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.展开更多
A new receiver is proposed, which uses the fiber optical parametric amplifier(FOPA) in optical code division multiple access(OCDMA) over free space optic(FSO) communication system. The noise tolerance as the performan...A new receiver is proposed, which uses the fiber optical parametric amplifier(FOPA) in optical code division multiple access(OCDMA) over free space optic(FSO) communication system. The noise tolerance as the performance index in this receiver is derived. The receiver can not only improve the noise tolerance but also change the pump data conveniently for adapting to the length variation of the coding sequence under a complex and fast-changing weather condition. The influence of different factors on the noise tolerance is analyzed, and a significant improvement of about 18.77 d B for the noise tolerance can be achieved when the pump power and the length of coding sequence are 5 W and 256, respectively.展开更多
基金Supported by National Natural Science Foundation of China under Grant No.10275025
文摘A single-mode laser noise model driven by quadratic colored pump noise and biased amplitude modulationsignal is proposed.The analytic expression of signal-to-noise ratio is calculated by using a new linearized procedure.Itis found that there are three different typies of stochastic resonance in the model:the conventional form of stochasticresonance,the stochastic resonance in the broad sense,and the bona fide SR.
文摘A novel method to partially compensate sigma-delta shaped noise is proposed. By injecting the compensation current into the passive loop filter during the delay time of the phase frequency detector（PFD）,a maximum reduction of the phase noise by about 16dB can be achieved. Compared to other compensation methods,the technique proposed here is relatively simple and easy to implement. Key building blocks for realizing the noise cancellation,including the delay variable PFD and compensation current source, are specially designed. Both the behavior level and circuit level simulation results are presented.
基金Project (51509111) supported by the National Natural Science Foundation of ChinaProject (2017M611721) supported by the China Postdoctoral Science Foundation+4 种基金Project (BY2016072-01) supported by the Association Innovation Fund of Production,Learning,and Research,ChinaProjects (GY2017001,GY2018025) supported by Zhenjiang Key Research and Development Plan,ChinaProjects (szjj2015-017,szjj2017-094) supported by the Open Research Subject of Key Laboratory of Fluid and Power Machinery,ChinaProject (GK201614) supported by Sichuan Provincial Key Lab of Process Equipment and Control,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China
文摘Investigations regarding the relation of noise performance for centrifugal pump operating in pump and turbine modes continue to be inadequate.This paper presents a series of comparisons of flow-induced noise for both operation modes.The interior flow-borne noise and structure modal were verified through experiments.The flow-borne noise was calculated by the acoustic boundary element method(ABEM),and the flow-induced structure noise was obtained by the coupled acoustic boundary element method(ABEM)/structure finite element method(SFEM).The results show that in pump mode,the pressure fluctuation in the volute is comparable to that in the outlet pipe,but in turbine mode,the pressure fluctuation in the impeller is comparable to that in the draft tube.The main frequency of interior flow-borne noise lies at blade passing frequency(BPF)and it shifts to the 9th BPF for interior flow-induced structure noise.The peak values at horizontal plane appear at the 5th BPF,and at axial plane,they get the highest sound pressure level(SPL)at the 8th BPF.Comparing with interior noise,the SPL of exterior flow-induced structure noise is incredibly small.At the 5th BPF,the pump body,cover and suspension show higher SPL in both modes.The outer walls of turbine generate relatively larger SPL than those of the pump.
基金The project supported by National Natural Science Foundation of China under Grant No. 10275025 and the Education Foundation of Hebei Province under Grant No. 2004D006.
文摘A two-dimensional single-mode laser model with cross-correlation between the real and imaginary parts of the colored quadric pump noise is investigated. A novel laser amplitude Langevin equation is obtained, in which the cross-correlation λp between the real and imaginary parts of the pump noise appears. The mean, variance, and skewness of first-passage-time are calculated. It is shown that the mean, variance, and skewness of first-passage-time are strongly affected by λp.
基金supported by the Chinese Academy of Sciences(Grant No.KJCX2-SW12-12-0)National Natural Science Foundation of China(Grant No 50536040).
文摘Pressure ratio is one of the important parameters for evaluating a thermoacoustic heat en- gine. A so-called acoustical pump, which is capable of significantly increasing pressure ratio of a ther- moacoustic heat engine, is proposed. Its operating principle is given. Also, a verification experiment is done with nitrogen gas in the energy-focused ther- moacoustic heat engine, showing that the pressure ratio increased from 1.25 to 1.47.
基金supported by the National Basic Research Program of China (973 Program) (No.2010CB328304)
文摘Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier （FOPA） is investigated. Taking the Raman effect into account, the modified coupled amplitude equations are fh-stly built, then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed. Besides, the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure （NF）.
基金supported by the National Natural Science Foundation of China (Nos.60907041,61003256 and 61071117)the Natural Science Foundation of CQ CSTC (No.2010BB2409)
文摘After the coupling equations of co-pumping,counter-pumping and bidirectional-pumping distributed Raman amplifiers(DRAs) are theoretically analyzed,the power distributions of these three DRAs are acquired with numerical analysis.The performance factors,such as net gain(NG),amplified spontaneous emissions(ASE) noise,double Rayleigh backscattering(DRB) noise,noise figure(NF) and optical signal noise ratio(OSNR),are discussed in depth.It can be found that the NGs of the three DRAs are almost equal.The counter-pumping scheme will induce higher ASE.And the co-pumping DRA has greater DRB noise,but its NF and OSNR are both better than the others'.Furthermore,the relations between signal power and NG,NF,OSNR are also investigated.It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power.The above conclusions can play a very important role in guiding the optimum design of DRA.
基金supported by the National Key Basic Research Special Foundation(Nos.2010CB327605 and 2010CB328300)the National Natural Science Foundation of China(No.61307109)+2 种基金the National High Technology Research and Development Program of China(Nos.2013AA031501 and 2013AA013303)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20120005120021)the Fundamental Research Funds for the Central Universities(No.2013RC1202)
文摘A new receiver is proposed, which uses the fiber optical parametric amplifier(FOPA) in optical code division multiple access(OCDMA) over free space optic(FSO) communication system. The noise tolerance as the performance index in this receiver is derived. The receiver can not only improve the noise tolerance but also change the pump data conveniently for adapting to the length variation of the coding sequence under a complex and fast-changing weather condition. The influence of different factors on the noise tolerance is analyzed, and a significant improvement of about 18.77 d B for the noise tolerance can be achieved when the pump power and the length of coding sequence are 5 W and 256, respectively.
