We propose a method that uses linear chirp modulated Gaussian functions as the elementary functions, by adaptively adjusting variances, time frequency centers and sweep rates, to decompose signals. By taking WVD, an ...We propose a method that uses linear chirp modulated Gaussian functions as the elementary functions, by adaptively adjusting variances, time frequency centers and sweep rates, to decompose signals. By taking WVD, an improved adaptive time frequency distribution is developed, which is non negative, free of cross term interference, and of better time frequency resolution. The paper presents an effective numerical algorithm to estimate the optimal parameters of the basis. Simulations indicate that the proposed approach is effective in analyzing signal's time frequency behavior.展开更多
Background SCN1A is the most well-recognized and commonly mutated gene related to epilepsy.This study analyzed the characteristic spatial and frequency distributions of SCN1A mutations,aiming to provide important insi...Background SCN1A is the most well-recognized and commonly mutated gene related to epilepsy.This study analyzed the characteristic spatial and frequency distributions of SCN1A mutations,aiming to provide important insight into the mutagenesis etiopathology of SCN1A-associated epilepsy.Methods Epilepsy-associated SCN1A variants were retrieved from the SCN1A mutation database,the HGMD database,and literature reviews.The base substitutions,mutation frequencies in CpG dinucleotides,and spatial distributions of mutations in terms of exons and structural domains were analyzed.Results A total of 2621 SCN1A variants were identifed in 5106 unrelated cases.The most common type was missense mutation,followed by frameshift mutations and splice site mutations.Among the missense mutations,transitions within CpG dinucleotides were much more recurrently identifed than transitions within non-CpG dinucleotides,and the most common type was the G>A transition.Among the nonsense mutations,the most predominant type of single-base substitution was the C>T transition,among which 75.3%(235/312)were within CpG sites.The most common“hotspot”codons for missense mutations were codons 101,946,and 1783;while for nonsense mutations it was codon 712.One-base deletion or insertion was the most common type of frameshift mutation,causing protein truncation.The three most common frameshift mutations were c.5536_5539delAAAC,c.4554dupA,and c.5010_5013delGTTT.Splice mutations were the most frequently identifed in exon 4 with a hotspot site c.602+1G>A.The spatial distribution of missense mutations showed that exons 22 and 4 had the highest mutation density(111 and 84 mutations per 100 bp,respectively),and exon 12 had the lowest mutation density,with 4 mutations per 100 bp.Further distribution analysis of the protein domains revealed that missense mutations were more common in the pore region and voltage sensor(231 mutations per 100 amino acids,respectively),and the protein truncation mutations were distributed evenly among the domains.Conclusions SCN1A mutations tend to cluster at distinct sites,depending on the characteristic CpG dinucleotides,exons,and functional domains.Higher mutation density in particular regions,such as exon 22 and exon 4,ofers promising targets for therapeutic genetic interventions.展开更多
Staff attendance information has always been an important part of corporate management.However,some opportunistic employees may consign others to punch their time cards,which hampers the authenticity of attendance and...Staff attendance information has always been an important part of corporate management.However,some opportunistic employees may consign others to punch their time cards,which hampers the authenticity of attendance and effectiveness of record keeping.Hence,it is necessary to develop an innovative anti-cheating system for office attendance.Radio-Frequency IDentification(RFID)offers new solutions to solve such problems because of its strong anti-interference capability and non-intrusiveness.In this paper,we present a smart attendance system that extracts distinguishable phase characteristics of individuals to enable recognition of various targets.A frequency distribution histogram is extracted as a fingerprint for recognition and the K-means clustering method is utilized for more fine-grained recognition of targets with similar features.Compared with traditional attendance mechanisms,RFID-based attendance systems are based on living biological characteristics,which greatly reduces the possibility of false records.To evaluate the performance of our system,we conducted extensive experiments.The results of which demonstrate the efficiency and accuracy of our system with an average accuracy of 92%.Moreover,the system evaluation shows that our design is robust against differences in the clothing worn and time of day,which further verifies the successful performance of our system.展开更多
In order to research possible influences of the adjustment of plant distribution on the development frequency of thunderstorms over the Leizhou Peninsula, mathematic statistic methods, including correlation analyses, ...In order to research possible influences of the adjustment of plant distribution on the development frequency of thunderstorms over the Leizhou Peninsula, mathematic statistic methods, including correlation analyses, 11 kinds of fitting models and all-variable regression methods, were used for analyses and research. The results show that the average trend of the number of annual thunderstorm days is descending obviously, and there are thunderstorms in all seasons, in which warm post-midday thunderstorms have taken up the most part, and high frequency is found from May to September, and the starting and ending dates of thunderstorms have a great annual discrepancy. The vegetation structure has been improved along with the reduction of rice fields and the area increment of sugarcane and fruits planting, which results in the decrease of the number of thunderstorm days; the change in the characteristics of winter spare fields, which is caused by the planting of vegetables, limits the formation of thunderstorms in early winter and late spring. Meanwhile, the area adjustment of peanut planting has little influence on the variation of thunderstorm days. The adjustment of principal crop distribution, such as rice, sugarcane, fruits and vegetables, may have obvious influence on the formation of thunderstorms, and sugarcane has the largest effect, followed in turn by rice, vegetables and fruits, and the adjustment of crop distribution has little influence on the starting and ending dates of thunderstorms.展开更多
We investigate the distribution of the switching current of a current-biased Josephson junction （CBJJ） and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum traject...We investigate the distribution of the switching current of a current-biased Josephson junction （CBJJ） and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current.展开更多
The study of synonyms based on corpus has become a hot topic in recent years,and the task of differentiating synonyms has always been a complex issue.The current study made an attempt to investigate the differences am...The study of synonyms based on corpus has become a hot topic in recent years,and the task of differentiating synonyms has always been a complex issue.The current study made an attempt to investigate the differences among English noun synonyms“opposition”,“resistance”and“defiance”from the perspective of frequency distribution,collocation and semantic prosody based on COCA.This research shows that in terms of frequency distribution,“opposition”and“resistance”are more frequently used than“defiance”.Both of the two are most commonly used in academic journals while“defiance”is most frequently used in fiction.All of these three words rarely appear in TV and movie subtitles.Second,from the perspective of collocation,“opposition”often collocates with words about politics and personal state,“resistance”usually appears with words concerning politics and medicine,and“defiance”mainly shows up in the fields of military,medicine,personal state and others.Third,from the dimension of semantic prosody,“opposition”presents negative semantic prosody,“resistance”has neutral semantic prosody,and“defiance”indicates mixed semantic prosody.The present study is able to enrich the relevant study on synonym differentiation,and highlight the importance of understanding the subtle differences among synonyms.展开更多
The estimation of model parameters is an important subject in engineering.In this area of work,the prevailing approach is to estimate or calculate these as deterministic parameters.In this study,we consider the model ...The estimation of model parameters is an important subject in engineering.In this area of work,the prevailing approach is to estimate or calculate these as deterministic parameters.In this study,we consider the model parameters from the perspective of random variables and describe the general form of the parameter distribution inference problem.Under this framework,we propose an ensemble Bayesian method by introducing Bayesian inference and the Markov chain Monte Carlo(MCMC)method.Experiments on a finite cylindrical reactor and a 2D IAEA benchmark problem show that the proposed method converges quickly and can estimate parameters effectively,even for several correlated parameters simultaneously.Our experiments include cases of engineering software calls,demonstrating that the method can be applied to engineering,such as nuclear reactor engineering.展开更多
Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, ...Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, and 12）. It is found that these statistical features of nearest neighboring nucleotides in human genome： （i） the frequency distribution is a linear function, and （ii） the correlation distribution is an inverse function. The coefficients of the linear function and inverse function depend on the GC content. It proposes the correlation distribution of nearest neighboring nucleotides for the first time and extends the descriptor about nearest neighboring nueleotides.展开更多
This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surf...This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.展开更多
By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "af...By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas nearby.It shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress change.The study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit magnitude.The duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above ML3.5.In this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress changes.It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases.展开更多
Aim To find an effective and fast algorithm to analyze undersampled signals. Methods\ The advantage of high order ambiguity function(HAF) algorithm is that it can analyze polynomial phase signals by phase rank reduct...Aim To find an effective and fast algorithm to analyze undersampled signals. Methods\ The advantage of high order ambiguity function(HAF) algorithm is that it can analyze polynomial phase signals by phase rank reduction. In this paper, it was first used to analyze the parameters of undersampled signals. When some conditions are satisfied, the problem of frequency confusion can be solved. Results and Conclusion\ As an example, we analyze undersampled linear frequency modulated signal. The simulation results verify the effectiveness of HAF algorithm. Compared with time frequency distribution, HAF algorithm reduces computation burden to a great extent, needs weak boundary conditions and doesn't have boundary effect.展开更多
Integrating distributed ultra-low-frequency vibration sensing and high-speed fiber optical communication can provide additional functionality under the current submarine telecommunication network,such as ocean seismic...Integrating distributed ultra-low-frequency vibration sensing and high-speed fiber optical communication can provide additional functionality under the current submarine telecommunication network,such as ocean seismic monitoring and geological exploration。展开更多
Bulk power systems show increasingly significant frequency spatial distribution characteristics(FSDCs),leading to a huge difference in the frequency response between regions.Existing uniform-frequency models based on ...Bulk power systems show increasingly significant frequency spatial distribution characteristics(FSDCs),leading to a huge difference in the frequency response between regions.Existing uniform-frequency models based on analytical methods are no longer applicable.This paper develops a reduced-order bus frequency response(BFR)model to preserve the FSDC and describe the frequency response of all buses.Its mathematical equation is proved to be isomorphic to the forced vibration of a mass-spring-damper system,and the closed-form solution(CFS)of the BFR model is derived by the modal analysis method and forced decoupling method in vibration mechanics.The correla tion between its mathematical equation and the state equation for small-signal stability analysis is discussed,and related pa rameters in the CFS are defined by the eigen-analysis method without any additional devices or tools.Case studies show that the proposed reduced-order BFR model and its CFS can im prove the solution accuracy while keeping the solution speed within milliseconds,which can preserve the significant FSDC of bulk power systems and represent a normalized mathematical description of distinct-frequency models.展开更多
The dynamic frequency control processes and economic operations of the large-scale power grids are separately applied.However,for the small inertia microgrids(MGs),the operating conditions tend to be more volatile due...The dynamic frequency control processes and economic operations of the large-scale power grids are separately applied.However,for the small inertia microgrids(MGs),the operating conditions tend to be more volatile due to relatively more uncontrollable entities being integrated.Hence,the frequency control solution of MGs should take the economic operation of MGs at a time-scale that is much shorter than the traditional economic dispatch of the large power grids.To this end,this paper proposes a two-layer coordinated frequency control strategy for MGs with enhanced economic operation consideration.For the upper optimal power-sharing layer,the distributed bisection algorithm is applied to obtain the optimal power sharing among heterogeneous resources.For the lower control layer,an autonomous control strategy that integrates both primary control and secondary control reference is applied by adopting the event-trigger mechanism.The proposed control approach can realize integrated active power control of MGs by simultaneously taking primary control,secondary control,and economic operation into consideration.Simulation studies with a heterogeneous resources-powered MG demonstrate its effectiveness.展开更多
Islanded microgrids(IMGs)offer a viable and efficient energy self-sustaining solution for distributed resources in remote areas.While without utility grid support,the frequency of IMG is susceptible to mismatches betw...Islanded microgrids(IMGs)offer a viable and efficient energy self-sustaining solution for distributed resources in remote areas.While without utility grid support,the frequency of IMG is susceptible to mismatches between demand and generation.Moreover,IMGs encounter uncertain and nonlinear load disturbances together with system parameter perturbation,which further compromises frequency stability.To this aim,this paper proposes a robust multi-virtual synchronous generators(multi-VSGs)coordinated control strategy for distributed secondary frequency regulation(DSFR)in IMGs,which exhibits minimal model dependency and avoids reliance on global information.Two critical methods are developed:(1)a robust VSG control framework that incorporates the linear active disturbance rejection control(LADRC)technique,which enables the estimation and effective elimination of uncertain load disturbances and system's parameter perturbations;(2)a novel secondorder consensus algorithm-based control law for robust secondary frequency regulation,which is featured with proper power sharing among different participants,suppressed power oscillation caused by response disparities,and reduced reliance on complex communication system.Building on methods(1)and(2),a novel multi-VSGs coordinated control strategy is proposed,providing a robust solution for IMG's frequency restoration,and its dynamic characteristics are explored in detail.The correctness and effectiveness of the proposal are verified by both simulation and the hardware-in-the-loop(HIL)experiment results across typical scenarios.展开更多
Stress-associated protein （SAP） has functions in maintaining plant cell elongation, embryo development and response to abiotic stresses. TaSAP1-A1, one of the Triticum aestivum SAP1 （TaSAP1） members located on whe...Stress-associated protein （SAP） has functions in maintaining plant cell elongation, embryo development and response to abiotic stresses. TaSAP1-A1, one of the Triticum aestivum SAP1 （TaSAP1） members located on wheat chromosome 7A was isolated for polymorphism analysis. HaplII of TaSAP1-A1 was found significantly associated with thousand-grain weight （TGW） in multiple environments. In this study, HaplII also made a positive contribution to TGW in Population 2. The distribution of TaSAP1-A1 HapIII was tracked among varieties released in different years and geographical environments of China. The frequency of HapIII showed an increasing trend during the breeding process in two different populations. The ItapIII was gradually selected and applied from 6.36% in landraces to 13.50% in modem varieties. These results exhibited that TaSAP1-A1 HapIII was positively selected during wheat breeding, which is beneficial for grain-yield improvement. The preferred HapIIl was initially selected and applied in the higher latitude areas of China in accord with the long day season and longer grain filling stage in these areas. Moreover, the frequency of HaplII in recent modem varieties was still quite low （19.29-26.67%）. It indicated a high application potential of TaSAP1-A 1 HapIII for improving grain yield in wheat breeding.展开更多
In order to analyze the composition and frequency distribution of acceleration signal in the process of projectile penetrating,this paper uses wavelet transform to decompose penetration acceleration signal to get the ...In order to analyze the composition and frequency distribution of acceleration signal in the process of projectile penetrating,this paper uses wavelet transform to decompose penetration acceleration signal to get the distribution of penetration acceleration signal in different frequency bands.Compared with the ideal acceleration signal curve and its characteristics,it can be concluded that the frequency range of the acceleration signal in the axis of the projectile and the vibration frequency range of the projectile are 31.25-62.5kHz and 62.5-125 kHz,respectively.Finally,the penetration acceleration signal curve is obtained by Simulink.展开更多
An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measur...An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measuring Mission(TRMM) sea surface temperature(SST) data,a relatively high resolution data for space.This phenomenon only shows up in boreal summer(June to September),and becomes obvious when WPWP SST is higher than 29℃.As observed,East Asian summer monsoon(EASM) impinges on Philippine Islands in July,which has an important impact on the formation and maintenance of the "sandwich structure".Winds affect the distribution of SST in two ways:one by increasing the local latent heat flux and the other by transporting cold water towards the southeast of Philippine Islands.展开更多
An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the l...An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.展开更多
文摘We propose a method that uses linear chirp modulated Gaussian functions as the elementary functions, by adaptively adjusting variances, time frequency centers and sweep rates, to decompose signals. By taking WVD, an improved adaptive time frequency distribution is developed, which is non negative, free of cross term interference, and of better time frequency resolution. The paper presents an effective numerical algorithm to estimate the optimal parameters of the basis. Simulations indicate that the proposed approach is effective in analyzing signal's time frequency behavior.
基金funded by Research Foundation of China Association Against Epilepsy(CU-2024-042)Medical Scientifc Research Foundation of Guangdong Province(A2024536)+1 种基金the National Natural Science Foundation of China(Grant No.82071548,Grant No.82301639 and Grant No.82201609)Guangzhou Medical University Student Innovation Ability Promoting Program(Grant No.2022A045 and Grant No.02-408-240603131135).
文摘Background SCN1A is the most well-recognized and commonly mutated gene related to epilepsy.This study analyzed the characteristic spatial and frequency distributions of SCN1A mutations,aiming to provide important insight into the mutagenesis etiopathology of SCN1A-associated epilepsy.Methods Epilepsy-associated SCN1A variants were retrieved from the SCN1A mutation database,the HGMD database,and literature reviews.The base substitutions,mutation frequencies in CpG dinucleotides,and spatial distributions of mutations in terms of exons and structural domains were analyzed.Results A total of 2621 SCN1A variants were identifed in 5106 unrelated cases.The most common type was missense mutation,followed by frameshift mutations and splice site mutations.Among the missense mutations,transitions within CpG dinucleotides were much more recurrently identifed than transitions within non-CpG dinucleotides,and the most common type was the G>A transition.Among the nonsense mutations,the most predominant type of single-base substitution was the C>T transition,among which 75.3%(235/312)were within CpG sites.The most common“hotspot”codons for missense mutations were codons 101,946,and 1783;while for nonsense mutations it was codon 712.One-base deletion or insertion was the most common type of frameshift mutation,causing protein truncation.The three most common frameshift mutations were c.5536_5539delAAAC,c.4554dupA,and c.5010_5013delGTTT.Splice mutations were the most frequently identifed in exon 4 with a hotspot site c.602+1G>A.The spatial distribution of missense mutations showed that exons 22 and 4 had the highest mutation density(111 and 84 mutations per 100 bp,respectively),and exon 12 had the lowest mutation density,with 4 mutations per 100 bp.Further distribution analysis of the protein domains revealed that missense mutations were more common in the pore region and voltage sensor(231 mutations per 100 amino acids,respectively),and the protein truncation mutations were distributed evenly among the domains.Conclusions SCN1A mutations tend to cluster at distinct sites,depending on the characteristic CpG dinucleotides,exons,and functional domains.Higher mutation density in particular regions,such as exon 22 and exon 4,ofers promising targets for therapeutic genetic interventions.
基金supported in part by the National Key Basic Research and Development (973) Program of China (No.2018YFB0803400)the Nature Science Foundation of Jiangsu for Distinguished Young Scientist (No.BK20170039)the National Natural Science Foundation of China (Nos.61702283,61873131,and 61872196)
文摘Staff attendance information has always been an important part of corporate management.However,some opportunistic employees may consign others to punch their time cards,which hampers the authenticity of attendance and effectiveness of record keeping.Hence,it is necessary to develop an innovative anti-cheating system for office attendance.Radio-Frequency IDentification(RFID)offers new solutions to solve such problems because of its strong anti-interference capability and non-intrusiveness.In this paper,we present a smart attendance system that extracts distinguishable phase characteristics of individuals to enable recognition of various targets.A frequency distribution histogram is extracted as a fingerprint for recognition and the K-means clustering method is utilized for more fine-grained recognition of targets with similar features.Compared with traditional attendance mechanisms,RFID-based attendance systems are based on living biological characteristics,which greatly reduces the possibility of false records.To evaluate the performance of our system,we conducted extensive experiments.The results of which demonstrate the efficiency and accuracy of our system with an average accuracy of 92%.Moreover,the system evaluation shows that our design is robust against differences in the clothing worn and time of day,which further verifies the successful performance of our system.
文摘In order to research possible influences of the adjustment of plant distribution on the development frequency of thunderstorms over the Leizhou Peninsula, mathematic statistic methods, including correlation analyses, 11 kinds of fitting models and all-variable regression methods, were used for analyses and research. The results show that the average trend of the number of annual thunderstorm days is descending obviously, and there are thunderstorms in all seasons, in which warm post-midday thunderstorms have taken up the most part, and high frequency is found from May to September, and the starting and ending dates of thunderstorms have a great annual discrepancy. The vegetation structure has been improved along with the reduction of rice fields and the area increment of sugarcane and fruits planting, which results in the decrease of the number of thunderstorm days; the change in the characteristics of winter spare fields, which is caused by the planting of vegetables, limits the formation of thunderstorms in early winter and late spring. Meanwhile, the area adjustment of peanut planting has little influence on the variation of thunderstorm days. The adjustment of principal crop distribution, such as rice, sugarcane, fruits and vegetables, may have obvious influence on the formation of thunderstorms, and sugarcane has the largest effect, followed in turn by rice, vegetables and fruits, and the adjustment of crop distribution has little influence on the starting and ending dates of thunderstorms.
基金Supported by the National Basic Research Program of China under Grant Nos 2011CBA00107,2011CB922104 and2011CBA00202the National Natural Science Foundation of China under Grant Nos 61371036,11234006,11227904 and 11474154+3 种基金the Natural Science Foundation of Jiangsu Province under Grant No BK2012013the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No 20120091110030the Dengfeng Project B of Nanjing University,Jiangsu Key Laboratory of Advanced Manipulating Techniques of Electromagnetic Wavesthe Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘We investigate the distribution of the switching current of a current-biased Josephson junction （CBJJ） and its dependence on the microwave frequency using two theoretical methods, one of which is the quantum trajectory method and the other is the master equation method. Both the methods show that the distribution of the switching current of CBJJ will exhibit double peaks in a certain range of microwave frequency if proper microwave power is given, and the gap between the two peaks will increase with the microwave frequency. The obtained results can be used to identify the energy difference of the ground and first excited states in a Josephson junction for any bias current.
文摘The study of synonyms based on corpus has become a hot topic in recent years,and the task of differentiating synonyms has always been a complex issue.The current study made an attempt to investigate the differences among English noun synonyms“opposition”,“resistance”and“defiance”from the perspective of frequency distribution,collocation and semantic prosody based on COCA.This research shows that in terms of frequency distribution,“opposition”and“resistance”are more frequently used than“defiance”.Both of the two are most commonly used in academic journals while“defiance”is most frequently used in fiction.All of these three words rarely appear in TV and movie subtitles.Second,from the perspective of collocation,“opposition”often collocates with words about politics and personal state,“resistance”usually appears with words concerning politics and medicine,and“defiance”mainly shows up in the fields of military,medicine,personal state and others.Third,from the dimension of semantic prosody,“opposition”presents negative semantic prosody,“resistance”has neutral semantic prosody,and“defiance”indicates mixed semantic prosody.The present study is able to enrich the relevant study on synonym differentiation,and highlight the importance of understanding the subtle differences among synonyms.
基金partially sponsored by the Natural Science Foundation of Shanghai(No.23ZR1429300)the Innovation Fund of CNNC(Lingchuang Fund)。
文摘The estimation of model parameters is an important subject in engineering.In this area of work,the prevailing approach is to estimate or calculate these as deterministic parameters.In this study,we consider the model parameters from the perspective of random variables and describe the general form of the parameter distribution inference problem.Under this framework,we propose an ensemble Bayesian method by introducing Bayesian inference and the Markov chain Monte Carlo(MCMC)method.Experiments on a finite cylindrical reactor and a 2D IAEA benchmark problem show that the proposed method converges quickly and can estimate parameters effectively,even for several correlated parameters simultaneously.Our experiments include cases of engineering software calls,demonstrating that the method can be applied to engineering,such as nuclear reactor engineering.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20173023 and No.90203012） and the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Zipf＇s approach in linguistics is utilized to analyze the statistical features of frequency and correlation of 16 nearest neighboring nucleotides （AA, AC, AG, …, TT） in 12 human chro- mosomes （Y, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, and 12）. It is found that these statistical features of nearest neighboring nucleotides in human genome： （i） the frequency distribution is a linear function, and （ii） the correlation distribution is an inverse function. The coefficients of the linear function and inverse function depend on the GC content. It proposes the correlation distribution of nearest neighboring nucleotides for the first time and extends the descriptor about nearest neighboring nueleotides.
基金supported by the National High Technology Research and Development Program (‘863’ Program) of China under contract No. 2012AA091701the Fundamental Research Fund for the Central University of China under the contract No. 2012212020211
文摘This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.
基金funded by the special project of the National Science&Technology Pillar Program during the Twelfth "Five-year Plan" Period(2012BAK19B02-05-02)
文摘By the aftershock frequency estimation method based on the calculation of coseismic static Coulomb stress changes and rate-and state-dependent fault constitutive law,we calculate the frequency of "direct "aftershocks of the Wenchuan earthquake related to coseismic static Coulomb stress changes in its aftershock zone and the areas nearby.It shows that the frequency is significantly lower than the truth in the main rupture zone,especially in the southern rupture zone,due to the decrease of stress level on the rupture plane of the main shock resulting from coseismic Coulomb stress change.The study also shows that the effect of the Coulomb stress change on the duration of aftershock activity is associated with the lower limit magnitude.The duration is about 15-16 months for aftershocks above ML4.0,and close to 60 months for aftershocks above ML3.5.In this period,the ratio of the"direct"aftershocks caused by coseismic Coulomb stress change ranges between 44.7% to48.6%,which suggests that,even in the "effective"period of coseismic Coulomb stress changes,about half of the aftershocks on the main shock rupture plane are independent of coseismic Coulomb stress changes.It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation,which are time dependent cases.
文摘Aim To find an effective and fast algorithm to analyze undersampled signals. Methods\ The advantage of high order ambiguity function(HAF) algorithm is that it can analyze polynomial phase signals by phase rank reduction. In this paper, it was first used to analyze the parameters of undersampled signals. When some conditions are satisfied, the problem of frequency confusion can be solved. Results and Conclusion\ As an example, we analyze undersampled linear frequency modulated signal. The simulation results verify the effectiveness of HAF algorithm. Compared with time frequency distribution, HAF algorithm reduces computation burden to a great extent, needs weak boundary conditions and doesn't have boundary effect.
基金National Natural Science Foundation of China(62435004,U22A2087,U21A20506,62475051)Guangdong Introducing Innovative and Entrepreneurial Teams of the Pearl River Talent Recruitment Program(2021ZT09X044).
文摘Integrating distributed ultra-low-frequency vibration sensing and high-speed fiber optical communication can provide additional functionality under the current submarine telecommunication network,such as ocean seismic monitoring and geological exploration。
基金supported in part by the National Natural Science Foundation of China(No.U22A20223).
文摘Bulk power systems show increasingly significant frequency spatial distribution characteristics(FSDCs),leading to a huge difference in the frequency response between regions.Existing uniform-frequency models based on analytical methods are no longer applicable.This paper develops a reduced-order bus frequency response(BFR)model to preserve the FSDC and describe the frequency response of all buses.Its mathematical equation is proved to be isomorphic to the forced vibration of a mass-spring-damper system,and the closed-form solution(CFS)of the BFR model is derived by the modal analysis method and forced decoupling method in vibration mechanics.The correla tion between its mathematical equation and the state equation for small-signal stability analysis is discussed,and related pa rameters in the CFS are defined by the eigen-analysis method without any additional devices or tools.Case studies show that the proposed reduced-order BFR model and its CFS can im prove the solution accuracy while keeping the solution speed within milliseconds,which can preserve the significant FSDC of bulk power systems and represent a normalized mathematical description of distinct-frequency models.
文摘The dynamic frequency control processes and economic operations of the large-scale power grids are separately applied.However,for the small inertia microgrids(MGs),the operating conditions tend to be more volatile due to relatively more uncontrollable entities being integrated.Hence,the frequency control solution of MGs should take the economic operation of MGs at a time-scale that is much shorter than the traditional economic dispatch of the large power grids.To this end,this paper proposes a two-layer coordinated frequency control strategy for MGs with enhanced economic operation consideration.For the upper optimal power-sharing layer,the distributed bisection algorithm is applied to obtain the optimal power sharing among heterogeneous resources.For the lower control layer,an autonomous control strategy that integrates both primary control and secondary control reference is applied by adopting the event-trigger mechanism.The proposed control approach can realize integrated active power control of MGs by simultaneously taking primary control,secondary control,and economic operation into consideration.Simulation studies with a heterogeneous resources-powered MG demonstrate its effectiveness.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22B20104,52407080,52277090,52207097)the International Science and Technology Cooperation Program of China(Grant No.2022YFE0129300)+2 种基金the Science and Technology Innovation Program of Hunan Province(Grant No.2023RC3102)the Excellent Innovation Youth Program of Changsha of China(Grant No.kq2209010)the Key Research and Development Program of Hunan Province(Grant No.2023GK2007)。
文摘Islanded microgrids(IMGs)offer a viable and efficient energy self-sustaining solution for distributed resources in remote areas.While without utility grid support,the frequency of IMG is susceptible to mismatches between demand and generation.Moreover,IMGs encounter uncertain and nonlinear load disturbances together with system parameter perturbation,which further compromises frequency stability.To this aim,this paper proposes a robust multi-virtual synchronous generators(multi-VSGs)coordinated control strategy for distributed secondary frequency regulation(DSFR)in IMGs,which exhibits minimal model dependency and avoids reliance on global information.Two critical methods are developed:(1)a robust VSG control framework that incorporates the linear active disturbance rejection control(LADRC)technique,which enables the estimation and effective elimination of uncertain load disturbances and system's parameter perturbations;(2)a novel secondorder consensus algorithm-based control law for robust secondary frequency regulation,which is featured with proper power sharing among different participants,suppressed power oscillation caused by response disparities,and reduced reliance on complex communication system.Building on methods(1)and(2),a novel multi-VSGs coordinated control strategy is proposed,providing a robust solution for IMG's frequency restoration,and its dynamic characteristics are explored in detail.The correctness and effectiveness of the proposal are verified by both simulation and the hardware-in-the-loop(HIL)experiment results across typical scenarios.
基金supported by the National Basic Research Program of China(2010CB951501)the National High-Tech R&D Program of China(2011AA100501)
文摘Stress-associated protein （SAP） has functions in maintaining plant cell elongation, embryo development and response to abiotic stresses. TaSAP1-A1, one of the Triticum aestivum SAP1 （TaSAP1） members located on wheat chromosome 7A was isolated for polymorphism analysis. HaplII of TaSAP1-A1 was found significantly associated with thousand-grain weight （TGW） in multiple environments. In this study, HaplII also made a positive contribution to TGW in Population 2. The distribution of TaSAP1-A1 HapIII was tracked among varieties released in different years and geographical environments of China. The frequency of HapIII showed an increasing trend during the breeding process in two different populations. The ItapIII was gradually selected and applied from 6.36% in landraces to 13.50% in modem varieties. These results exhibited that TaSAP1-A1 HapIII was positively selected during wheat breeding, which is beneficial for grain-yield improvement. The preferred HapIIl was initially selected and applied in the higher latitude areas of China in accord with the long day season and longer grain filling stage in these areas. Moreover, the frequency of HaplII in recent modem varieties was still quite low （19.29-26.67%）. It indicated a high application potential of TaSAP1-A 1 HapIII for improving grain yield in wheat breeding.
文摘In order to analyze the composition and frequency distribution of acceleration signal in the process of projectile penetrating,this paper uses wavelet transform to decompose penetration acceleration signal to get the distribution of penetration acceleration signal in different frequency bands.Compared with the ideal acceleration signal curve and its characteristics,it can be concluded that the frequency range of the acceleration signal in the axis of the projectile and the vibration frequency range of the projectile are 31.25-62.5kHz and 62.5-125 kHz,respectively.Finally,the penetration acceleration signal curve is obtained by Simulink.
基金National Natural Science Foundation of China (40975038, 40830106)National Basic Research Program of China (973 Program:2012CB955604)+1 种基金Program from China Meteorological Administration (GYHY200906008)Project 111 (B07036)
文摘An inconsecutive high frequency distribution with a"sandwich structure"pattern for high temperature warm water warmer than 29℃ in the western Pacific warm pool(WPWP) was found using Tropical Rainfall Measuring Mission(TRMM) sea surface temperature(SST) data,a relatively high resolution data for space.This phenomenon only shows up in boreal summer(June to September),and becomes obvious when WPWP SST is higher than 29℃.As observed,East Asian summer monsoon(EASM) impinges on Philippine Islands in July,which has an important impact on the formation and maintenance of the "sandwich structure".Winds affect the distribution of SST in two ways:one by increasing the local latent heat flux and the other by transporting cold water towards the southeast of Philippine Islands.
基金supported by the Special Scientific Research Projects for Public Interest(No.GYHY201006021 and GYHY201106016)the National Natural Science Foundation of China(No.41205040 and 40930952)
文摘An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.
