A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system ...A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system can be approximated by the solution of the simplified equations in the sense of mean square. An example is presented to illustrate the applications of the limit theorem.展开更多
Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described o...Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described on the basis of geometric singular perturbation theory. Then, the impact of time delay on the structure of the slow manifold of synchronized system is obtained by using the method of stability switch, and thus, time-delay effects on synchronization features are stated. It is shown the time delay cannot qualitatively affect the synchronization mechanism, however, it can result in the drift of the optimal coupling strength.展开更多
In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in te...In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in termsof mechanical properties were compared, and highly sig-nificant correlation between two systems were obtaineddespite some considerable differences in the measurementprinciples of KES - F and FAST systems.展开更多
BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effec...BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effectiveness of GLP-1RAs in these situations.AIM To evaluate the safety and efficacy of GLP-1RA in patients with T2DM fasting during Ramadan.METHODS Electronic databases were systematically searched for relevant studies that featured GLP-1RA in the intervention arm and other glucose-lowering medications in the control arm.The primary outcome was adverse events(AEs)during Ramadan for both groups;other outcomes included changes in glycemic and anthropometric measures during the peri-Ramadan period.RESULTS Four studies[three randomized-controlled trials with low risk of bias(RoB)and one prospective observational study with serious RoB]involving 754 subjects were analyzed.GLP-1RA group achieved greater glycated hemoglobin reduction than the non-GLP-1RA group[mean difference(MD):-0.31%,95%CI:-0.61 to-0.01,P=0.04,I2=77%]with a lower risk of documented symptomatic hypoglycemia(risk ratio=0.38,95%CI:0.16 to 0.88,P=0.02).Any AEs,serious AEs,or AEs that led to treatment discontinuation were comparable between the two groups.The GLP-1RA group experienced greater weight loss compared to the non-GLP-1RA group(MD:-2.0 kg,95%CI:-3.37 to-0.63,P=0.004,I2=95%).There were comparable changes in blood pressure and lipid profile between the two groups.GLP-1RA users experienced higher risks of gastrointestinal AEs,nausea,and vomiting;however,the risks of heartburn,abdominal pain,and diarrhea were similar in both groups.CONCLUSION Limited evidence suggests that GLP-1RAs are safe for T2DM management during Ramadan,offering modest benefits in blood sugar control and weight loss.Large multicenter trials are needed to confirm their safety and efficacy in at-risk populations,improving clinical practice decision-making.展开更多
With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter ...With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.展开更多
Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or ...Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.展开更多
A programmable high-accuracy system was proposed to collect and process telemetric fast varying signals,which consists of pre-circuit,analog-to-digital（A/D）conversion unit and signal collection and processing part.P...A programmable high-accuracy system was proposed to collect and process telemetric fast varying signals,which consists of pre-circuit,analog-to-digital（A/D）conversion unit and signal collection and processing part.Performance analysis demonstrates that this novel telemetry-acquisition method is a potential solution to rapidly process fast varying signals and efficiently utilize telemetry channel.展开更多
A fast version of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）/Institute of Atmospheric Physics （IAP） climate system model is briefly documented. Th...A fast version of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）/Institute of Atmospheric Physics （IAP） climate system model is briefly documented. The fast coupled model employs a low resolution version of the atmospheric component Grid Atmospheric Model of IAP/LASG （GAMIL）, with the other parts of the model, namely an oceanic component LASG/IAP Climate Ocean Model （LICOM）, land component Common Land Model （CLM）, and sea ice component from National Center for Atmospheric Research Community Climate System Model （NCAR CCSM2）, as the same as in the standard version of LASG/IAP Flexible Global Ocean Atmosphere Land System model （FGOALS_g）. The parameterizations of physical and dynamical processes of the atmospheric component in the fast version are identical to the standard version, although some parameter values are different. However, by virtue of reduced horizontal resolution and increased time-step of the most time-consuming atmospheric component, it runs faster by a factor of 3 and can serve as a useful tool for longterm and large-ensemble integrations. A 1000-year control simulation of the present-day climate has been completed without flux adjustments. The final 600 years of this simulation has virtually no trends in global mean sea surface temperatures and is recommended for internal variability studies. Several aspects of the control simulation＇s mean climate and variability are evaluated against the observational or reanalysis data. The strengths and weaknesses of the control simulation are evaluated. The mean atmospheric circulation is well simulated, except in high latitudes. The Asian-Australian monsoonal meridional cell shows realistic features, however, an artificial rainfall center is located to the eastern periphery of the Tibetan Plateau persists throughout the year. The mean bias of SST resembles that of the standard version, appearing as a ＂double ITCZ＂ （Inter-Tropical Convergence Zone） associated with a westward extension of the equatorial eastern Pacific cold tongue. The sea ice extent is acceptable but has a higher concentration. The strength of Atlantic meridional overturning is 27.5 Sv. Evidence from the 600-year simulation suggests a modulation of internal variability on ENSO frequency, since both regular and irregular oscillations of ENSO are found during the different time periods of the long-term simulation.展开更多
In actual power systems,most of the high-voltage buses of the transformers are zero injection buses without load or generation.Power injections into these buses are strictly 0,so based on Kirchhoff's current law(K...In actual power systems,most of the high-voltage buses of the transformers are zero injection buses without load or generation.Power injections into these buses are strictly 0,so based on Kirchhoff's current law(KCL),equality constraints should be used to handle these buses in a state estimation model.It is a challenge to ensure that these zero injection constraints can be strictly satisfied without losing computational efficiency.展开更多
This paper develops a fast filtering algorithm based on vibration systems theory and neural information exchange approach. The characters, including the derivation process and parameter analysis, are discussed and the...This paper develops a fast filtering algorithm based on vibration systems theory and neural information exchange approach. The characters, including the derivation process and parameter analysis, are discussed and the feasibility and the effectiveness are testified by the filtering performance compared with various filtering methods, such as the fast wavelet transform algorithm, the particle filtering method and our previously developed single degree of freedom vibration system filtering algorithm, according to simulation and practical approaches. Meanwhile, the comparisons indicate that a significant advantage of the proposed fast filtering algorithm is its extremely fast filtering speed with good filtering perfi^rmance. Further, the developed fast filtering algorithm is applied to the navigation and positioning system of the micro motion robot, which is a high real-time requirement for the signals preprocessing. Then, the preprocessing data is used to estimate the heading angle error and the attitude angle error of the micro motion robot. The estimation experiments illustrate the high practicality of the proposed fast filtering algorithm.展开更多
Changes in distribution density,morphology and secretory content of endocrine cells in the gastro-entero-pancreatic system of black-spotted frogs Rana nigromaculata before and after fasting were investigated using imm...Changes in distribution density,morphology and secretory content of endocrine cells in the gastro-entero-pancreatic system of black-spotted frogs Rana nigromaculata before and after fasting were investigated using immunohistochemistry and antisera to six gut hormones.Six types of endocrine cells were detected in the digestive tract of Rana nigromaculata,including 5-hydroxytryptamine(5-HT),gastrin(GAS),somatostatin(SOM),glucagon(GLU),pancreatic polypeptide(PP)and vasoactive intestinal polypeptide(VIP)cells.After fasting,the density of 5-HT cells in the esophagus,cardia and fundus,GAS cells in the fundus and pylorus,PP cells in the fundus decreased significantly(P<0.01),while SOM cells in the cardia,GLU cells in the rectum increased significantly(P<0.01).The cytoplasmic processes of 5-HT cells became shorter or not detectable.The secretory content of GAS cells reduced in the cardia.The positive immunostaining reaction in the perinuclear region of SOM cells in the cardia,fundus and pylorus became weaker,while the staining intensity in the periphery of these cells became stronger.VIP cells were not detectable in the whole digestive tract after fasting.Five types of endocrine cells were found in the pancreas of Rana nigromaculata,including 5-HT,GAS,SOM,GLU and PP cells.After fasting,the density of 5-HT cells decreased slightly(P>0.05),while SOM,GAS,GLU and PP cells increased significantly(P<0.01).Furthermore,the secretory content of GLU cells increased significantly.Considering their functionalities,our results indicate that the changes of GEP endocrine cells in Rana nigromaculata responded adaptively to starvation-induced stress.展开更多
This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems.Here the two delayed's have different meanings.The delayed bifurcation means that the bi...This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems.Here the two delayed's have different meanings.The delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious distance.In a time-delayed system,the evolution of the system depends not only on the present state but also on past states.In this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's theory.It shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.展开更多
This paper presents the design of an experimental battlefield dynamic scanning and staring imaging system based on a fast steering mirror(FSM), which is capable of real-time monitoring of hot targets and wide-area rec...This paper presents the design of an experimental battlefield dynamic scanning and staring imaging system based on a fast steering mirror(FSM), which is capable of real-time monitoring of hot targets and wide-area reconnaissance of hot regions. First,the working principle and working sequence of the FSM are briefly analyzed. The mathematical model of the FSM system is built by modeling its dynamic and electrical properties, and the rationality of the model is validated by means of model identification. Second,the influence of external sources of disturbance such as the carrier and moment on the control precision of the FSM is effectively suppressed by the jointly controlling of proportional integral(PI)and disturbance observer(DOB), thus realizing a high precision and strong robustness control of the FSM system. Then, this paper designs an experimental prototype and introduces a special optical structure to enable the infrared camera to share the FSM with the visible light camera. Finally, the influence of the velocity difference between the mirror of the FSM and the rotating platform on the imaging quality of the system is experimentally analyzed by using the image sharpness evaluation method based on point sharpness. A good dynamic scanning and staring imaging result is achieved when the velocity of these two components correspond.展开更多
A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequ...A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequency domains is given.The pilots in accordance with a novel random pilot matrix in both time and frequency domains are sent to measure the delay-Doppler sparsity channel.The relatively nonzero channel coefficients are tracked by random pilots at a sampling rate significantly below the Nyquist rate.The sparsity channels are estimated from a very limited number of channel measurements by the basis pursuit algorithm.The proposed algorithm can effectively improve the channel estimation performance when the number of pilot symbols is reduced with improvement of throughput efficiency.展开更多
We theoretically explore the tunability of magnomechanically induced transparency(MMIT) phenomenon and fastslow light effect in a hybrid cavity magnomechanical system in which a high-quality yttrium iron garnet(YIG) s...We theoretically explore the tunability of magnomechanically induced transparency(MMIT) phenomenon and fastslow light effect in a hybrid cavity magnomechanical system in which a high-quality yttrium iron garnet(YIG) sphere and an atomic ensemble are placed inside a microwave cavity. In the probe output spectrum, we can observe magnoninduced transparency(MIT) and MMIT due to the photon-magnon and phonon-magnon couplings. We further investigate the effect of atomic ensemble on the absorption spectrum. The results show that better transparency can be obtained by choosing appropriate atomic ensemble parameters. We give an explicit explanation for the mechanism of the Fano resonance phenomenon. Moreover, we discuss phenomena of slow-light propagation. The maximum group delay increases significantly with the increasing atom–cavity coupling strength, and the conversion between slow light and fast light can also be achieved by adjusting the atom–cavity coupling strength. These results may have potential applications for quantum information processing and high precision measurements.展开更多
This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The st...This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The stability and drift rate of the frequency standard are calculated using 1-year monitoring data.The UTC-NIM Disciplined Oscillator(NIMDO)system improves the system time accuracy and stability to the level of 5 ns.Pulsar timing observations were carried out for several months.The weighted RMS of timing residuals reaches the level of less than 3.0μs.展开更多
A novel real time fast electron bremsstrahlung (FEB) diagnostic system based on the lutetium yttrium oxyorthosilicate scintillators (LYSO) and silicon photomultipliers (SiPM) has been developed for tokamak.The diagnos...A novel real time fast electron bremsstrahlung (FEB) diagnostic system based on the lutetium yttrium oxyorthosilicate scintillators (LYSO) and silicon photomultipliers (SiPM) has been developed for tokamak.The diagnostic system is dedicated to study the FEB emission in the hard x-ray (HXR) energy range between 10 and 200 keV during the lower hybrid current drive.The system consists of a detection module and three data acquisition and processing (DAP)boards.The detection module consists of annulus LYSO-SiPM detector array and a 12-channel preamplifier module.The DAP boards upload the data to the host computer for displaying and storing through PXI bus.The time and space resolutions of the system are 10 ms and 4 cm,respectively.The experimental results can show the evolution over time and the spatial distribution of FEB.This paper presents the system performance and typical discharge results.展开更多
基金supported by the National Nature Science Foundation of China (11372247 and 11102157)Program for NCET, the Shaanxi Project for Young New Star in Science and TechnologyNPU Foundation for Fundamental Research and SRF for ROCS, SEM
文摘A limit theorem which can simplify slow–fast dynamical systems driven by fractional Brownian motion with the Hurst parameter H inside the（1/2, 1） interval has been proved. The slow variables of the original system can be approximated by the solution of the simplified equations in the sense of mean square. An example is presented to illustrate the applications of the limit theorem.
文摘Time-delay effects on synchronization features of delay-coupled slow-fast van der Pol systems are investigated in the present paper. The synchronization mechanism of “slow-manifold adjustment” is firstly described on the basis of geometric singular perturbation theory. Then, the impact of time delay on the structure of the slow manifold of synchronized system is obtained by using the method of stability switch, and thus, time-delay effects on synchronization features are stated. It is shown the time delay cannot qualitatively affect the synchronization mechanism, however, it can result in the drift of the optimal coupling strength.
文摘In order to clarify the connections and differences be.tween KES- F and FAST, fifteen polyester- based fab-rics were selected and the experiments were strictly mea-sured. The test results between the two systems in termsof mechanical properties were compared, and highly sig-nificant correlation between two systems were obtaineddespite some considerable differences in the measurementprinciples of KES - F and FAST systems.
基金thankful to Dr.Marina George Kudiyirickal MSc,MJDF-RCS,PhD for providing us the audio core tip of this article.
文摘BACKGROUND Data on the use of glucagon-like peptide-1 receptor agonists(GLP-1RAs)in individuals with type 2 diabetes mellitus(T2DM)during Ramadan fasting is limited.No meta-analysis has summarized the safety and effectiveness of GLP-1RAs in these situations.AIM To evaluate the safety and efficacy of GLP-1RA in patients with T2DM fasting during Ramadan.METHODS Electronic databases were systematically searched for relevant studies that featured GLP-1RA in the intervention arm and other glucose-lowering medications in the control arm.The primary outcome was adverse events(AEs)during Ramadan for both groups;other outcomes included changes in glycemic and anthropometric measures during the peri-Ramadan period.RESULTS Four studies[three randomized-controlled trials with low risk of bias(RoB)and one prospective observational study with serious RoB]involving 754 subjects were analyzed.GLP-1RA group achieved greater glycated hemoglobin reduction than the non-GLP-1RA group[mean difference(MD):-0.31%,95%CI:-0.61 to-0.01,P=0.04,I2=77%]with a lower risk of documented symptomatic hypoglycemia(risk ratio=0.38,95%CI:0.16 to 0.88,P=0.02).Any AEs,serious AEs,or AEs that led to treatment discontinuation were comparable between the two groups.The GLP-1RA group experienced greater weight loss compared to the non-GLP-1RA group(MD:-2.0 kg,95%CI:-3.37 to-0.63,P=0.004,I2=95%).There were comparable changes in blood pressure and lipid profile between the two groups.GLP-1RA users experienced higher risks of gastrointestinal AEs,nausea,and vomiting;however,the risks of heartburn,abdominal pain,and diarrhea were similar in both groups.CONCLUSION Limited evidence suggests that GLP-1RAs are safe for T2DM management during Ramadan,offering modest benefits in blood sugar control and weight loss.Large multicenter trials are needed to confirm their safety and efficacy in at-risk populations,improving clinical practice decision-making.
基金co-supported by the National Natural Science Foundation of China(No.52477063)the National Key Research and Development Program of China(No.2023YFF0719100)。
文摘With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.
基金supported by the National Natural Science Foundation of China(11032009 and 11272236)
文摘Flexible joints are usually used to transfer velocities in robot systems and may lead to delays in motion transformation due to joint flexibility. In this paper, a linkrotor structure connected by a flexible joint or shaft is firstly modeled to be a slow-fast delayed system when moment of inertia of the lightweight link is far less than that of the heavy rotor. To analyze the stability and oscillations of the slowfast system, the geometric singular perturbation method is extended, with both slow and fast manifolds expressed analytically. The stability of the slow manifold is investigated and critical boundaries are obtained to divide the stable and the unstable regions. To study effects of the transformation delay on the stability and oscillations of the link, two quantitatively different driving forces derived from the negative feedback of the link are considered. The results show that one of these two typical driving forces may drive the link to exhibit a stable state and the other kind of driving force may induce a relaxation oscillation for a very small delay. However, the link loses stability and undergoes regular periodic and bursting oscillation when the transformation delay is large. Basically, a very small delay does not affect the stability of the slow manifold but a large delay affects substantially.
文摘A programmable high-accuracy system was proposed to collect and process telemetric fast varying signals,which consists of pre-circuit,analog-to-digital（A/D）conversion unit and signal collection and processing part.Performance analysis demonstrates that this novel telemetry-acquisition method is a potential solution to rapidly process fast varying signals and efficiently utilize telemetry channel.
基金Acknowledgements. This work was jointly supported by the Chinese Academy of Sciences through the International Partnership Creative Group entitled ＂The Climate System Model Development and Application Studies＂, the Major State Basic Research Development Program of China （973 Program） under Grant No. 2005CB321703, and the National Natural Science Foundation of China （Grant Nos. 40675050, 40221503, 40625014）. The long-term integration of the coupled model was finished on the Lenovo DeepComp 6800 supercomputer at the Supercomputing Center of the Chinese Academy of Sciences, and the IBM SP690 at the Institute of Atmospheric Physics, Chinese Academy of Sciences. The authors appreciate the contribution of Drs. R. C. Yu, Y. Q. Yu, H. L. Liu, W. P. Zheng, J. Li, X. G Xin, and Mrs. H. Wan, H. M. Li in the model development and validations.
文摘A fast version of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）/Institute of Atmospheric Physics （IAP） climate system model is briefly documented. The fast coupled model employs a low resolution version of the atmospheric component Grid Atmospheric Model of IAP/LASG （GAMIL）, with the other parts of the model, namely an oceanic component LASG/IAP Climate Ocean Model （LICOM）, land component Common Land Model （CLM）, and sea ice component from National Center for Atmospheric Research Community Climate System Model （NCAR CCSM2）, as the same as in the standard version of LASG/IAP Flexible Global Ocean Atmosphere Land System model （FGOALS_g）. The parameterizations of physical and dynamical processes of the atmospheric component in the fast version are identical to the standard version, although some parameter values are different. However, by virtue of reduced horizontal resolution and increased time-step of the most time-consuming atmospheric component, it runs faster by a factor of 3 and can serve as a useful tool for longterm and large-ensemble integrations. A 1000-year control simulation of the present-day climate has been completed without flux adjustments. The final 600 years of this simulation has virtually no trends in global mean sea surface temperatures and is recommended for internal variability studies. Several aspects of the control simulation＇s mean climate and variability are evaluated against the observational or reanalysis data. The strengths and weaknesses of the control simulation are evaluated. The mean atmospheric circulation is well simulated, except in high latitudes. The Asian-Australian monsoonal meridional cell shows realistic features, however, an artificial rainfall center is located to the eastern periphery of the Tibetan Plateau persists throughout the year. The mean bias of SST resembles that of the standard version, appearing as a ＂double ITCZ＂ （Inter-Tropical Convergence Zone） associated with a westward extension of the equatorial eastern Pacific cold tongue. The sea ice extent is acceptable but has a higher concentration. The strength of Atlantic meridional overturning is 27.5 Sv. Evidence from the 600-year simulation suggests a modulation of internal variability on ENSO frequency, since both regular and irregular oscillations of ENSO are found during the different time periods of the long-term simulation.
文摘In actual power systems,most of the high-voltage buses of the transformers are zero injection buses without load or generation.Power injections into these buses are strictly 0,so based on Kirchhoff's current law(KCL),equality constraints should be used to handle these buses in a state estimation model.It is a challenge to ensure that these zero injection constraints can be strictly satisfied without losing computational efficiency.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60901074,51075092,61005076,and 61175107)the National High Technology Research and Development Program of China(Grant No.2007AA042105)the Natural Science Foundation of Heilongjiang Province,China(Grant No.E200903)
文摘This paper develops a fast filtering algorithm based on vibration systems theory and neural information exchange approach. The characters, including the derivation process and parameter analysis, are discussed and the feasibility and the effectiveness are testified by the filtering performance compared with various filtering methods, such as the fast wavelet transform algorithm, the particle filtering method and our previously developed single degree of freedom vibration system filtering algorithm, according to simulation and practical approaches. Meanwhile, the comparisons indicate that a significant advantage of the proposed fast filtering algorithm is its extremely fast filtering speed with good filtering perfi^rmance. Further, the developed fast filtering algorithm is applied to the navigation and positioning system of the micro motion robot, which is a high real-time requirement for the signals preprocessing. Then, the preprocessing data is used to estimate the heading angle error and the attitude angle error of the micro motion robot. The estimation experiments illustrate the high practicality of the proposed fast filtering algorithm.
基金supported by Open Fund of Key Laboratory of Bio-Macromolecular Evolution(No.2006B001)Foundation for outstanding academic team of Zoological Biology in Anhui Normal UniversitySpecial Foundation for Provincial Key Laboratories of Biotic Environment and Ecological Safety and Key Laboratory for Conservation and Use of Important Biological Resources of Anhui Province
文摘Changes in distribution density,morphology and secretory content of endocrine cells in the gastro-entero-pancreatic system of black-spotted frogs Rana nigromaculata before and after fasting were investigated using immunohistochemistry and antisera to six gut hormones.Six types of endocrine cells were detected in the digestive tract of Rana nigromaculata,including 5-hydroxytryptamine(5-HT),gastrin(GAS),somatostatin(SOM),glucagon(GLU),pancreatic polypeptide(PP)and vasoactive intestinal polypeptide(VIP)cells.After fasting,the density of 5-HT cells in the esophagus,cardia and fundus,GAS cells in the fundus and pylorus,PP cells in the fundus decreased significantly(P<0.01),while SOM cells in the cardia,GLU cells in the rectum increased significantly(P<0.01).The cytoplasmic processes of 5-HT cells became shorter or not detectable.The secretory content of GAS cells reduced in the cardia.The positive immunostaining reaction in the perinuclear region of SOM cells in the cardia,fundus and pylorus became weaker,while the staining intensity in the periphery of these cells became stronger.VIP cells were not detectable in the whole digestive tract after fasting.Five types of endocrine cells were found in the pancreas of Rana nigromaculata,including 5-HT,GAS,SOM,GLU and PP cells.After fasting,the density of 5-HT cells decreased slightly(P>0.05),while SOM,GAS,GLU and PP cells increased significantly(P<0.01).Furthermore,the secretory content of GLU cells increased significantly.Considering their functionalities,our results indicate that the changes of GEP endocrine cells in Rana nigromaculata responded adaptively to starvation-induced stress.
基金supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No.200430)in part by the National Natural Science Foundation of China (Grant Nos.10825207,10532050)
文摘This paper presents an investigation on the phenomenon of delayed bifurcation in time-delayed slow-fast differential systems.Here the two delayed's have different meanings.The delayed bifurcation means that the bifurcation does not happen immediately at the bifurcation point as the bifurcation parameter passes through some bifurcation point,but at some other point which is above the bifurcation point by an obvious distance.In a time-delayed system,the evolution of the system depends not only on the present state but also on past states.In this paper,the time-delayed slow-fast system is firstly simplified to a slow-fast system without time delay by means of the center manifold reduction,and then the so-called entry-exit function is defined to characterize the delayed bifurcation on the basis of Neishtadt's theory.It shows that delayed Hopf bifurcation exists in time-delayed slow-fast systems,and the theoretical prediction on the exit-point is in good agreement with the numerical calculation,as illustrated in the two illustrative examples.
基金supported by the National Defense Pre-research Project of China during the 12th Five-year Plan Period(4040570201)Innovation Project of Military Academy(ZYX14060014)
文摘This paper presents the design of an experimental battlefield dynamic scanning and staring imaging system based on a fast steering mirror(FSM), which is capable of real-time monitoring of hot targets and wide-area reconnaissance of hot regions. First,the working principle and working sequence of the FSM are briefly analyzed. The mathematical model of the FSM system is built by modeling its dynamic and electrical properties, and the rationality of the model is validated by means of model identification. Second,the influence of external sources of disturbance such as the carrier and moment on the control precision of the FSM is effectively suppressed by the jointly controlling of proportional integral(PI)and disturbance observer(DOB), thus realizing a high precision and strong robustness control of the FSM system. Then, this paper designs an experimental prototype and introduces a special optical structure to enable the infrared camera to share the FSM with the visible light camera. Finally, the influence of the velocity difference between the mirror of the FSM and the rotating platform on the imaging quality of the system is experimentally analyzed by using the image sharpness evaluation method based on point sharpness. A good dynamic scanning and staring imaging result is achieved when the velocity of these two components correspond.
基金supported by the National Natural Science Foundation of China(60972056)the Innovation Foundation of Shanghai Education Committee(09ZZ89)Shanghai Leading Academic Discipline Project and STCSM(S30108and08DZ2231100)
文摘A compressed sensing（CS） based channel estimation algorithm is proposed by using the delay-Doppler sparsity of the fast fading channel.A compressive basis expansion channel model with sparsity in both time and frequency domains is given.The pilots in accordance with a novel random pilot matrix in both time and frequency domains are sent to measure the delay-Doppler sparsity channel.The relatively nonzero channel coefficients are tracked by random pilots at a sampling rate significantly below the Nyquist rate.The sparsity channels are estimated from a very limited number of channel measurements by the basis pursuit algorithm.The proposed algorithm can effectively improve the channel estimation performance when the number of pilot symbols is reduced with improvement of throughput efficiency.
基金the National Natural Science Foundation of China (Grant No. 62061028)the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology (Grant No. ammt2021A4)+4 种基金the Foundation for Distinguished Young Scientists of Jiangxi Province (Grant No. 20162BCB23009)the Open Research Fund Program of the State Key Laboratory of LowDimensional Quantum Physics (Grant No. KF202010)the Interdisciplinary Innovation Fund of Nanchang University (Grant No. 9166-27060003-YB12)the Open Research Fund Program of Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of Education (Grant No. OEIAM202004)the Graduate Innovation Special Fund of Jiangxi Province (Grant No. YC2021-S054)。
文摘We theoretically explore the tunability of magnomechanically induced transparency(MMIT) phenomenon and fastslow light effect in a hybrid cavity magnomechanical system in which a high-quality yttrium iron garnet(YIG) sphere and an atomic ensemble are placed inside a microwave cavity. In the probe output spectrum, we can observe magnoninduced transparency(MIT) and MMIT due to the photon-magnon and phonon-magnon couplings. We further investigate the effect of atomic ensemble on the absorption spectrum. The results show that better transparency can be obtained by choosing appropriate atomic ensemble parameters. We give an explicit explanation for the mechanism of the Fano resonance phenomenon. Moreover, we discuss phenomena of slow-light propagation. The maximum group delay increases significantly with the increasing atom–cavity coupling strength, and the conversion between slow light and fast light can also be achieved by adjusting the atom–cavity coupling strength. These results may have potential applications for quantum information processing and high precision measurements.
基金supported by the Joint Research Fund in Astronomy(Grant Nos.U1931129,U1631115 and U1831117)under cooperative agreement between NSFC and Chinese Academy of Sciences(CAS)NSFC-STINT Grant 11611130023(CH2015-6360)the National Natural Science Foundation of China(NSFC,Grant No.11403054)
文摘This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The stability and drift rate of the frequency standard are calculated using 1-year monitoring data.The UTC-NIM Disciplined Oscillator(NIMDO)system improves the system time accuracy and stability to the level of 5 ns.Pulsar timing observations were carried out for several months.The weighted RMS of timing residuals reaches the level of less than 3.0μs.
基金National Natural Science Foundation of China (No. 11575184).
文摘A novel real time fast electron bremsstrahlung (FEB) diagnostic system based on the lutetium yttrium oxyorthosilicate scintillators (LYSO) and silicon photomultipliers (SiPM) has been developed for tokamak.The diagnostic system is dedicated to study the FEB emission in the hard x-ray (HXR) energy range between 10 and 200 keV during the lower hybrid current drive.The system consists of a detection module and three data acquisition and processing (DAP)boards.The detection module consists of annulus LYSO-SiPM detector array and a 12-channel preamplifier module.The DAP boards upload the data to the host computer for displaying and storing through PXI bus.The time and space resolutions of the system are 10 ms and 4 cm,respectively.The experimental results can show the evolution over time and the spatial distribution of FEB.This paper presents the system performance and typical discharge results.
