A fractional frequency divider based on phase switching and negative feedback delta-sigma modulator(NF-DSM) is presented. The phase switching circuit, realized by switching 8 signals generated by a divider-by-4 circui...A fractional frequency divider based on phase switching and negative feedback delta-sigma modulator(NF-DSM) is presented. The phase switching circuit, realized by switching 8 signals generated by a divider-by-4 circuit, is adopted to reduce the frequency division step. The NF-DSM, which can obtain smooth output spectra, is proposed to generate the fractional part of the division ratio, moreover, the integer part of the division ratio is realized by a divider-by-2/3 circuit chain. Fabricated in TSMC 0.18 μm RF CMOS technology, the fractional frequency divider achieves a measured operation frequency from 0.5 GHz to 8 GHz. With a 1.8 V supply voltage, the maximum current consumption of the whole divider is 17.5 mA, and the chip area is 0.58 mm^2, including the pads.展开更多
The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the ...The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the finite-difference timedomain method,which is used to directly solve Maxwell＇s equations,can consider the lateral variation of the refractive index and obtain an accurate convergence effect.The simulation results show that e-rays and o-rays bend in different directions when the in-plane switching blue phase liquid crystal display is driven by the operating voltage.The finitedifference time-domain method should be used when the distribution of the liquid crystal in the liquid crystal display has a large lateral change.展开更多
A new type of large\|displacement actuator called RAINBOW (Reduced And Internally Biased Oxide Wafer) was fabricated by a chemical reduction of PSZT antiferroelectric ceramic. It is found that PSZT was easily reduced ...A new type of large\|displacement actuator called RAINBOW (Reduced And Internally Biased Oxide Wafer) was fabricated by a chemical reduction of PSZT antiferroelectric ceramic. It is found that PSZT was easily reduced and the optimal conditions for producing RAINBOW samples were determined to be 870℃ for 2~3 h. The AFE\|FE phase transitions occur at lower field strength in RAINBOWs compared with normal PSZT. Larger axial displacement (about 190μm) was obtained from the RAINBOWs by application of electric ...展开更多
A new type of large-displacement actuator called reduced and internally biased oxide wafer(RAINBOW)is fabricated by chemical reduction of Pb(Sn,Zr,Ti)O3(PSZT)antiferroelectric ceramics and its properties are investiga...A new type of large-displacement actuator called reduced and internally biased oxide wafer(RAINBOW)is fabricated by chemical reduction of Pb(Sn,Zr,Ti)O3(PSZT)antiferroelectric ceramics and its properties are investigated.It is found that PSZT is easily reduced and the optimal conditions for producing RAINBOW samples are determined to be 870℃for 2-3 h.The antiferroelectrics-ferroelectrics phase transitions occur at lower field strength in RAINBOW actuators compared with normal PSZT actuators.Large axial displacements are also obtained from the RAINBOW actuator by application of electric fields exceeding the phase switching level.However,the field-induced displacement of the RAINBOW actuator is dependent on the manner of applying load on the samples.展开更多
Equatorial central Pacific precipitation experienced a prominent decline in the late 1990 s.This change was previously attributed to a La Nina-like mean sea surface temperature(SST)change in the Pacific Ocean associat...Equatorial central Pacific precipitation experienced a prominent decline in the late 1990 s.This change was previously attributed to a La Nina-like mean sea surface temperature(SST)change in the Pacific Ocean associated with a phase switch of the Interdecadal Pacific Oscillation.Here,using a series of model experiments,the authors reveal that the El Nino-related interannual SST anomalies contributed largely to the precipitation decrease over the equatorial central Pacific.This El Nino SST effect was due to the change in the amplitude of El Nino events in the late 1990 s.The 1980-98 decade had more large-amplitude El Nino events than the 1999-2014 decade.The nonlinear precipitation response to SST anomalies resulted in a larger decadal mean precipitation in the 1980-98 decade than in the 1999-2014 decade.The results highlight the importance of El Nino amplitude change in future climate change related to global warming.展开更多
Implementation of robot-based motion control in optical machining demonstrably enhances the machining quality.The introduction of motion-copying method enables learning and replicating manipulation from experienced te...Implementation of robot-based motion control in optical machining demonstrably enhances the machining quality.The introduction of motion-copying method enables learning and replicating manipulation from experienced technicians.Nevertheless,the location uncertainties of objects and frequent switching of manipulated spaces in practical applications impose constraints on their further advancement.To address this issue,a motion-copying system with a symbol-sequence-based phase switch control(SSPSC)scheme was developed by transferring the operating skills and intelligence of technicians to mechanisms.The manipulation process is decomposed,symbolised,rearranged,and reproduced according to the manufacturing characteristics regardless of the change in object location.A force-sensorless adaptive sliding-mode-assisted reaction force observer(ASMARFOB),wherein a novel dual-layer adaptive law was designed for high-performance fine force sensing,was established.The uniformly ultimate boundedness(UUB)of the ASMARFOB is guaranteed based on the Lyapunov stability theory,and the switching stability of the SSPSC was examined.Validation simulations and experiments demonstrated that the proposed method enables better motion reproduction with high consistency and adaptability.The findings of this study can provide effective theoretical and practical guidance for high-precision intelligent optical manufacturing.展开更多
With the rapid evolution of wireless communication technology, integrating various communication modes in a mobile terminal has become the popular trend. Because of this, multi-standard wireless technology is one of t...With the rapid evolution of wireless communication technology, integrating various communication modes in a mobile terminal has become the popular trend. Because of this, multi-standard wireless technology is one of the hot spots in current research. This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications. High-speed divider-by-2 with traditional source- coupled-logic is designed for very wide band usage. Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step. The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider. A-E modulator is achieved by an improved MASH 1-1-1 structure. This structure has excellent performance in many ways, such as noise, spur and input dynamic range. Fabricated in TSMC 0.18/tin CMOS process, the fractional-N frequency divider occupies a chip area of 1130 × 510μm^2 and it can correctly divide within the frequency range of 0.8-9 GHz. With 1.8 V supply voltage, its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.展开更多
The wake induced vibration(WIV)of a one-and two-degree-of-freedom(1DOF,2DOF)downstream wave-cone cylinder(WCC)behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically inve...The wake induced vibration(WIV)of a one-and two-degree-of-freedom(1DOF,2DOF)downstream wave-cone cylinder(WCC)behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically investigated at subcritical Reynolds number of 3900 by using shear stressed transfer(SST)k-ωturbulence model.The streamwise pitch ratios(P/Dm)vary from 4 to 6 with a fixed incident angleα=8°.Experimental measurements were also performed for the validation of the present numerical models.It is found that the largest vibration amplitude in crossflow direction occurred at P/Dm=4,Ur=8 with small difference of streamwise vibration at P/Dm=4,6.Different from single wavy-cone cylinder(SWCC),the downstream flexible one of a pair staggered WCCs got larger vibration amplitude during phase switching stage instead of in-phase stage.The upstream wake will suppress the triple frequency of main frequency in the power spectra density(PSD)functions of Cl but stimulate the double one of that.An intriguing vibration mechanism happened in all 2DOF cases where the trajectory of downstream WCC is a significant ellipse rather than a figure of 8.The transformation of phase switching and the variation of the main frequency of drag coefficient(Cd)can be explained by the vortex-shedding modes of downstream WCC.展开更多
基金Supported by the National Natural Science Foundation of China(No.61674037)National Key Research and Development Program of China(No.2016YFC0800400)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A fractional frequency divider based on phase switching and negative feedback delta-sigma modulator(NF-DSM) is presented. The phase switching circuit, realized by switching 8 signals generated by a divider-by-4 circuit, is adopted to reduce the frequency division step. The NF-DSM, which can obtain smooth output spectra, is proposed to generate the fractional part of the division ratio, moreover, the integer part of the division ratio is realized by a divider-by-2/3 circuit chain. Fabricated in TSMC 0.18 μm RF CMOS technology, the fractional frequency divider achieves a measured operation frequency from 0.5 GHz to 8 GHz. With a 1.8 V supply voltage, the maximum current consumption of the whole divider is 17.5 mA, and the chip area is 0.58 mm^2, including the pads.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304074,61475042,and 11274088)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2015202320 and GCC2014048)the Key Subject Construction Project of Hebei Province University,China
文摘The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the finite-difference timedomain method,which is used to directly solve Maxwell＇s equations,can consider the lateral variation of the refractive index and obtain an accurate convergence effect.The simulation results show that e-rays and o-rays bend in different directions when the in-plane switching blue phase liquid crystal display is driven by the operating voltage.The finitedifference time-domain method should be used when the distribution of the liquid crystal in the liquid crystal display has a large lateral change.
基金National Natural Science F oundation of China(5 990 2 0 0 2 ) Aeronautical Science F oundation(99G5 2 0 65 )
文摘A new type of large\|displacement actuator called RAINBOW (Reduced And Internally Biased Oxide Wafer) was fabricated by a chemical reduction of PSZT antiferroelectric ceramic. It is found that PSZT was easily reduced and the optimal conditions for producing RAINBOW samples were determined to be 870℃ for 2~3 h. The AFE\|FE phase transitions occur at lower field strength in RAINBOWs compared with normal PSZT. Larger axial displacement (about 190μm) was obtained from the RAINBOWs by application of electric ...
基金This project is supported by National Natural Science Foundation of China(No.50135030)Aeronautical Science Foundation of China(No.04G52042)Pre-research fund of Weapons&Equipments of China(No.51412010505HK0208).
文摘A new type of large-displacement actuator called reduced and internally biased oxide wafer(RAINBOW)is fabricated by chemical reduction of Pb(Sn,Zr,Ti)O3(PSZT)antiferroelectric ceramics and its properties are investigated.It is found that PSZT is easily reduced and the optimal conditions for producing RAINBOW samples are determined to be 870℃for 2-3 h.The antiferroelectrics-ferroelectrics phase transitions occur at lower field strength in RAINBOW actuators compared with normal PSZT actuators.Large axial displacements are also obtained from the RAINBOW actuator by application of electric fields exceeding the phase switching level.However,the field-induced displacement of the RAINBOW actuator is dependent on the manner of applying load on the samples.
基金supported by the National Key Research and Development Program of China [grant number2016YFA0600603]the National Natural Science Foundation of China [grant numbers 41775080,41530425,41721004,and 41475081]
文摘Equatorial central Pacific precipitation experienced a prominent decline in the late 1990 s.This change was previously attributed to a La Nina-like mean sea surface temperature(SST)change in the Pacific Ocean associated with a phase switch of the Interdecadal Pacific Oscillation.Here,using a series of model experiments,the authors reveal that the El Nino-related interannual SST anomalies contributed largely to the precipitation decrease over the equatorial central Pacific.This El Nino SST effect was due to the change in the amplitude of El Nino events in the late 1990 s.The 1980-98 decade had more large-amplitude El Nino events than the 1999-2014 decade.The nonlinear precipitation response to SST anomalies resulted in a larger decadal mean precipitation in the 1980-98 decade than in the 1999-2014 decade.The results highlight the importance of El Nino amplitude change in future climate change related to global warming.
基金supported in part by the National Science Foundation of China,under grant numbers T2122001 and 12203049in part by the Key Research Program of Frontier Sciences,CAS,under grant number ZDBS-LY-JSC044in part by the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant number 2023230.
文摘Implementation of robot-based motion control in optical machining demonstrably enhances the machining quality.The introduction of motion-copying method enables learning and replicating manipulation from experienced technicians.Nevertheless,the location uncertainties of objects and frequent switching of manipulated spaces in practical applications impose constraints on their further advancement.To address this issue,a motion-copying system with a symbol-sequence-based phase switch control(SSPSC)scheme was developed by transferring the operating skills and intelligence of technicians to mechanisms.The manipulation process is decomposed,symbolised,rearranged,and reproduced according to the manufacturing characteristics regardless of the change in object location.A force-sensorless adaptive sliding-mode-assisted reaction force observer(ASMARFOB),wherein a novel dual-layer adaptive law was designed for high-performance fine force sensing,was established.The uniformly ultimate boundedness(UUB)of the ASMARFOB is guaranteed based on the Lyapunov stability theory,and the switching stability of the SSPSC was examined.Validation simulations and experiments demonstrated that the proposed method enables better motion reproduction with high consistency and adaptability.The findings of this study can provide effective theoretical and practical guidance for high-precision intelligent optical manufacturing.
文摘With the rapid evolution of wireless communication technology, integrating various communication modes in a mobile terminal has become the popular trend. Because of this, multi-standard wireless technology is one of the hot spots in current research. This paper presents a wideband fractional-N frequency divider of the multi-standard wireless transceiver for many applications. High-speed divider-by-2 with traditional source- coupled-logic is designed for very wide band usage. Phase switching technique and a chain of divider-by-2/3 are applied to the programmable frequency divider with 0.5 step. The phase noise of the whole frequency synthesizer will be decreased by the narrower step of programmable frequency divider. A-E modulator is achieved by an improved MASH 1-1-1 structure. This structure has excellent performance in many ways, such as noise, spur and input dynamic range. Fabricated in TSMC 0.18/tin CMOS process, the fractional-N frequency divider occupies a chip area of 1130 × 510μm^2 and it can correctly divide within the frequency range of 0.8-9 GHz. With 1.8 V supply voltage, its division ratio ranges from 62.5 to 254 and the total current consumption is 29 mA.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11972268,12372232).
文摘The wake induced vibration(WIV)of a one-and two-degree-of-freedom(1DOF,2DOF)downstream wave-cone cylinder(WCC)behind a stationary equal-size upstream wave-cone cylinder in the staggered arrangement is numerically investigated at subcritical Reynolds number of 3900 by using shear stressed transfer(SST)k-ωturbulence model.The streamwise pitch ratios(P/Dm)vary from 4 to 6 with a fixed incident angleα=8°.Experimental measurements were also performed for the validation of the present numerical models.It is found that the largest vibration amplitude in crossflow direction occurred at P/Dm=4,Ur=8 with small difference of streamwise vibration at P/Dm=4,6.Different from single wavy-cone cylinder(SWCC),the downstream flexible one of a pair staggered WCCs got larger vibration amplitude during phase switching stage instead of in-phase stage.The upstream wake will suppress the triple frequency of main frequency in the power spectra density(PSD)functions of Cl but stimulate the double one of that.An intriguing vibration mechanism happened in all 2DOF cases where the trajectory of downstream WCC is a significant ellipse rather than a figure of 8.The transformation of phase switching and the variation of the main frequency of drag coefficient(Cd)can be explained by the vortex-shedding modes of downstream WCC.
