A continuous time delay-difference model(CTDDM) has been established that considers continuous time delays of biological processes.The southern Atlantic albacore(Thunnus alalunga) stock is the one of the commercially ...A continuous time delay-difference model(CTDDM) has been established that considers continuous time delays of biological processes.The southern Atlantic albacore(Thunnus alalunga) stock is the one of the commercially important tuna population in the marine world.The age structured production model(ASPM) and the surplus production model(SPM) have already been used to assess the albacore stock.However,the ASPM requires detailed biological information and the SPM lacks the biological realism.In this study,we focus on applying a CTDDM to the southern Atlantic albacore(T.alalunga) species,which provides an alternative method to assess this fishery.It is the first time that CTDDM has been provided for assessing the Atlantic albacore(T.alalunga) fishery.CTDDM obtained the 80%confidence interval of MSY(maximum sustainable yield) of(21 510 t,23 118 t).The catch in 2011(24 100 t) is higher than the MSY values and the relative fishing mortality ratio(F_(2011)/F_(MSY)) is higher than 1.0.The results of CTDDM were analyzed to verify the proposed methodology and provide reference information for the sustainable management of the southern Atlantic albacore stock.The CTDDM treats the recruitment,the growth,and the mortality rates as all varying continuously over time and fills gaps between ASPM and SPM in this stock assessment.展开更多
A generalized continuous time random walk model which is dependent on environmental damping is proposed in which the two key parameters of the usual random walk theory： the jumping distance and the waiting time, are ...A generalized continuous time random walk model which is dependent on environmental damping is proposed in which the two key parameters of the usual random walk theory： the jumping distance and the waiting time, are replaced by two new ones： the pulse velocity and the flight time. The anomalous diffusion of a free particle which is characterized by the asymptotical mean square displacement （x^2（t）） - t^a is realized numerically and analysed theoretically, where the value of the power index a is in a region of 0 〈 a 〈 2. Particularly, the damping leads to a sub-diffusion when the impact velocities are drawn from a Gaussian density function and the super-diffusive effect is related to statistical extremes, which are called rare-though-dominant events.展开更多
The generalized master equation for the space-time coupled continuous time random walk is derived analytically, in which the space-time coupling is considered through the correlated function 9（t） ～ t^γ, 0 ≤ γ 〈...The generalized master equation for the space-time coupled continuous time random walk is derived analytically, in which the space-time coupling is considered through the correlated function 9（t） ～ t^γ, 0 ≤ γ 〈 2, and the probability density function ω（t） of a particle＇s waiting time t follows a power law form for large t： ω（t） ～t^-（1＋α）, 0 〈 α 〈 1. The results indicate that the expressions of the generalized master equation are determined by the correlation exponent 7 and the long-tailed index α of the waiting time. Moreover, the diffusion results obtained from the generalized master equation are in accordance with the previous known results and the numerical simulation results.展开更多
The goal of this paper is to propose a unique control method that permits the evolution of both timed continuous Petri net （TCPN） and T-timed discrete Petri net （T-TDPN） from an initial state to a desired one. Mod...The goal of this paper is to propose a unique control method that permits the evolution of both timed continuous Petri net （TCPN） and T-timed discrete Petri net （T-TDPN） from an initial state to a desired one. Model predictive control （MPC） is a robust control scheme against perturbation and a consistent real-time constraints method. Hence, the proposed approach is studied using the MPC. However, the computational complexity may prevent the use of the MPC for large systems and for large prediction horizons. Then, the proposed approach provides some new techniques in order to reduce the high computational complexity; among them one is taking constant control actions during the prediction.展开更多
Dear Editor,This letter proposes a reinforcement learning-based predictive learning algorithm for unknown continuous-time nonlinear systems with observation loss.Firstly,we construct a temporal nonzero-sum game over p...Dear Editor,This letter proposes a reinforcement learning-based predictive learning algorithm for unknown continuous-time nonlinear systems with observation loss.Firstly,we construct a temporal nonzero-sum game over predictive control input sequences,deriving multiple optimal predictive control input sequences from its solution.展开更多
A dissipative time crystal is an emergent phase in driven-dissipative quantum many-body systems,characterized by sustained oscillations that break time-translation symmetry spontaneously.Here,we explore nonequilibrium...A dissipative time crystal is an emergent phase in driven-dissipative quantum many-body systems,characterized by sustained oscillations that break time-translation symmetry spontaneously.Here,we explore nonequilibrium phase transitions in a dissipative Rydberg system driven by a microwave(MW)field and demonstrate their critical sensitivity to high-precision MW sensing.Distinct dynamical regimes are identified,including monostable,bistable,and oscillatory phases under mean-field coupling.Unlike single-particle detection—where the beating signal decays linearly with MW field strength—the time crystalline phase exhibits high sensitivity to MW perturbations,with rapid,discontinuous frequency switching near the monostable-oscillatory boundary.The abrupt transition is rooted in spontaneous symmetry breaking in time and is fundamentally insensitive to the background noise.On this basis,a minimum detectable MW field strength on the order of 1 nV/cm is achieved by leveraging this sensitivity.Our results establish a framework for controlling time crystalline phases with external fields and advance MW sensing through many-body effects.展开更多
A wide bandwidth continuous time sigma delta ADC is implemented in 130 nm CMOS. A detailed nonidealities analysis （excess loop delay, clock jitter, finite gain and GBW, comparator offset and DAC mismatch） is perform...A wide bandwidth continuous time sigma delta ADC is implemented in 130 nm CMOS. A detailed nonidealities analysis （excess loop delay, clock jitter, finite gain and GBW, comparator offset and DAC mismatch） is performed developed in Matlab/Simulink. This design is targeted for wide bandwidth applications such as video or wireless base-stations. A third-order continuous time sigma delta modulator comprises a third-order RC operational- amplifier-based loop filter and 3-bit internal quantizer operated at 512 MHz clock frequency. The sigma delta ADC achieves 60 dB SNR and 59.3 dB SNDR over a 16-MHz signal band at an OSR of 16. The power consumption of the CT sigma delta modulator is 22 mW from the 1.2-V supply.展开更多
Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(C...Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(CBI process)converges almost surely.If an x log(x)moment condition on the branching mechanism does not hold,then the limit is zero.If this x log(x)moment condition holds,then we prove L1 convergence as well.The projection of the limit on any left non-Perron eigenvector of the branching mean matrix is vanishing.If,in addition,a suitable extra power moment condition on the branching mechanism holds,then we provide the correct scaling for the projection of a CBI process on certain left non-Perron eigenvectors of the branching mean matrix in order to have almost sure and L1 limit.Moreover,under a second order moment condition on the branching and immigration mechanisms,we prove L2 convergence of an appropriately scaled process and the above-mentioned projections as well.A representation of the limits is also provided under the same moment conditions.展开更多
A new mixed-integrator-based bi-quad cell is proposed. An alternative synthesis mechanism of complex poles is proposed compared with source-follower-based bi-quad cells which is designed applying the positive feedback...A new mixed-integrator-based bi-quad cell is proposed. An alternative synthesis mechanism of complex poles is proposed compared with source-follower-based bi-quad cells which is designed applying the positive feedback technique. Using the negative feedback technique to combine different integrators, the proposed bi-quad cell synthesizes complex poles for designing a continuous time filter. It exhibits various advantages including compact topology, high gain, no parasitic pole, no CMFB circuit, and high capability. The fourth-order Butterworth lowpass filter using the proposed cells has been fabricated in 0.18μm CMOS technology. The active area occupied by the filter with test buffer is only 200 × 170 μm^2. The proposed filter consumes a low power of 201 μW and achieves a 68.5 dB dynamic range.展开更多
We study the asymptotic relation among the maximum of continuous weakly and strongly dependent stationary Gaussian process, the maximum of this process sampled at discrete time points, and the partial sum of this proc...We study the asymptotic relation among the maximum of continuous weakly and strongly dependent stationary Gaussian process, the maximum of this process sampled at discrete time points, and the partial sum of this process. It is shown that these two extreme values and the sum are asymptotically independent if the grid of the discrete time points is sufficiently sparse and the Gaussian process is weakly dependent, and asymptotically dependent if the grid points are Pickands grids or dense grids.展开更多
A continuous time random walk is a random walk subordinated to a renewal process used in physics to model anomalous diffusion. In this paper, we establish a Chung-type law of the iterated logarithm for continuous time...A continuous time random walk is a random walk subordinated to a renewal process used in physics to model anomalous diffusion. In this paper, we establish a Chung-type law of the iterated logarithm for continuous time random walk with jumps and waiting times in the domains of attraction of stable laws.展开更多
For the continuous time Markov chain with transition function P（t） on Z d ＋ , we give the necessary and sufficient conditions for the existence of its Siegmund dual with transition function P - （t）. If Q, the q-m...For the continuous time Markov chain with transition function P（t） on Z d ＋ , we give the necessary and sufficient conditions for the existence of its Siegmund dual with transition function P - （t）. If Q, the q-matrix of P（t）, is uniformly bounded, we show that the Siegmund dual relation can be expressed directly in terms of q-matrices, and a sufficient condition under which the Q-function is the Siegnmnd dual of some Q-function is also given.展开更多
The present paper aims to show the impact of continuous time calculation on life insurance pricing and reserving in the Algerian context. The discrete time approach allows insurance companies to facilitate calculation...The present paper aims to show the impact of continuous time calculation on life insurance pricing and reserving in the Algerian context. The discrete time approach allows insurance companies to facilitate calculation process but with less accuracy. This approach implies constancy of death quotients during a year. However, the death risk is a continuous function in time. For more accuracy and equity in pricing, calculation needs to consider the exact dates of different payments and also a continuous capitalization process. This gives more adequate premium with fewer hypotheses. This work shows how insurers can propose more adequate pricing using the same actuarial life table.展开更多
This paper deals with the continuous time Markov decision programming (briefly CTMDP) withunbounded reward rate.The economic criterion is the long-run average reward. To the models withcountable state space,and compac...This paper deals with the continuous time Markov decision programming (briefly CTMDP) withunbounded reward rate.The economic criterion is the long-run average reward. To the models withcountable state space,and compact metric action sets,we present a set of sufficient conditions to ensurethe existence of the stationary optimal policies.展开更多
This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random ...This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random walk with a log-normal jump distribution and a time-waiting distribution following a tempered a-stable probability law. Based on the random walk model, a fractional Fokker-Planck equation （FFPE） with tempered a-stable waiting times was obtained. Through the comparison of observed data and simulated results from the random walk model and FFPE model with tempered a-stable waiting times, it can be concluded that the behavior of the rainfall process is globally reproduced, and the FFPE model with tempered a-stable waiting times is more efficient in reproducing the observed behavior.展开更多
In this paper, we set up continuous time model with Poisson Process to analyze demand of investment-oriented life insurance. Individual life time is assumed random, and he is received fixed income, investment-oriented...In this paper, we set up continuous time model with Poisson Process to analyze demand of investment-oriented life insurance. Individual life time is assumed random, and he is received fixed income, investment-oriented life insurance is an important financial asset under this model. Dynamic programming is applied to analyze this problem. The optimal explicit solutions are obtained in the case of CRRA utilities, and draw its demand curve with numerical simulation.展开更多
BACKGROUND Stroke is the leading cause of adult lifelong disability worldwide.A stroke is an acute cerebrovascular disease with a variety of causes and corresponding clinical symptoms.Around 75%of surviving stroke pat...BACKGROUND Stroke is the leading cause of adult lifelong disability worldwide.A stroke is an acute cerebrovascular disease with a variety of causes and corresponding clinical symptoms.Around 75%of surviving stroke patients experience impaired nerve function,and some suffer from traumatic fractures,which can lead to special care needs.AIM To determine the effect of timing theory continuous care,with resistance training,on the rehabilitation and mental health of caregivers and stroke patients with traumatic fractures.METHODS Between January 2017 to March 2021,we selected 100 hospital admissions with post-stroke hemiplegia complicated with a traumatic fracture.Two participant groups were created:(1)Control group:given resistance training;and(2)Observation group:given timing theory continuous care combined with resistance training.The degree of satisfaction and differences in bone and phosphorus metabolism indexes between the two groups were compared.The self-perceived burden scale(SPBS)and caregiver burden questionnaire were used to evaluate the psychological health of patients and caregivers.The Harris hip function score,ability of daily living(ADL)scale,and global quality of life questionnaire(GQOL-74)were used to evaluate hip function,ability of daily living,and quality of life.RESULTS Data were collected prior to and after intervention.Alkaline phosphatase(ALP),osteocalcin,and vitamin D3 in the observation group and control group increased after intervention(P<0.05),and carboxy-terminal peptide of type I collagenβSpecial sequence(β-CTX)decreased(P<0.05).ALP and osteocalcin in the observation group were higher than in the control group(P<0.05).There was no significant difference inβ-CTX and vitamin D3 between the two groups(P>0.05).The SPBS score of the observation group was lower and the ADL score was higher than the control group.The burden score was lower and the Harris hip function and GQOL-74 scores were higher than that of the control group(P<0.05).The observation group’s satisfaction rating was 94.00%,which was higher than the rating from the control group(P<0.05).CONCLUSION Timing theory continuous nursing with resistance training can reduce hip dysfunction in stroke patients with a traumatic fracture and enhance quality of life and mental health of patients and caregivers.展开更多
Mediterranean forest communities are particularly diverse but at risk due to their sensitivity to global warming.Understanding the long-term vulnerability of Mediterranean vegetation to climate change is crucial for c...Mediterranean forest communities are particularly diverse but at risk due to their sensitivity to global warming.Understanding the long-term vulnerability of Mediterranean vegetation to climate change is crucial for conservation and management purposes.Studies on past changes of forest communities in response to climate change at ecologically meaningful resolutions(i.e.,decadal time scales) are therefore essential,but still very rare.The Holocene thermal maximum(HTM;ca.10,000-5,000 cal years before the present(BP)) may be used to study species and community responses to warmer conditions than during recent decades.We performed highresolution multiproxy palaeoecological analyses on sediments from crater Lake Mezzano in central Italy to reconstruct vegetation,diversity,and fire dynamics between 8,450 and 7,050 cal years BP.Ordination,crosscorrelation,and species-response analyses were used to investigate the response of Mediterranean forest communities to HTM climate warming,human impact,and fire.Vegetational changes prior to 7,450 cal years BP were driven by climate.Fagus sylvatica spread into mixed deciduous oak forests during the Early Holocene in response to declining seasonality(cooler summers and warmer winters).Subsequently,Fagus sylvatica declined and evergreen Quercus ilex expanded after 8,200 cal years BP when the climate became warmer.Although reduced,Fagus sylvatica remained important together with deciduous oaks.The co-existence of Fagus sylvatica and evergreen Quercus forests is extremely rare today.Human impact significantly affected forest vegetation after7,450 cal years BP,when Neolithic agricultural activities became important,ultimately extirpating these special communities but fostering the overall biodiversity.However,their past occurrence in several central Italian calderas during the HTM suggests that these environments provided habitats that permitted the thriving of cooltemperate forests of Fagus sylvatica under mesomediterranean conditions,with summers ca.1-2℃ warmer than today.Cool and moist calderas may thus become increasingly important for maintaining Mediterranean mesophilous forest species under global warming conditions.展开更多
In the analysis and design for linear systems in the form of state space,it is undisputed that state responses play a fundamentally important role.For continuous-time linear time-invariant(CT-LTI)systems,the well-know...In the analysis and design for linear systems in the form of state space,it is undisputed that state responses play a fundamentally important role.For continuous-time linear time-invariant(CT-LTI)systems,the well-known result is that the state responses are given in terms of matrix exponential functions[1].For discrete-time linear time-invariant(DT-LTI)systems,the state responses are expressed in terms of matrix power functions[1].展开更多
The polaron problem is a very old problem in condensed matter physics that dates back to the thirties,but still remains largely unsolved today,especially when electron–electron interaction is taken into consideration...The polaron problem is a very old problem in condensed matter physics that dates back to the thirties,but still remains largely unsolved today,especially when electron–electron interaction is taken into consideration.The presence of both electron–electron and electron–phonon interactions in the problem invalidates most existing numerical methods,which are either computationally too expensive or simply intractable.The continuous-time quantum Monte Carlo(CTQMC)methods could tackle this problem,but they are only effective on the imaginarytime axis.In this work,we present a method based on tensor networks and the path integral formalism to solve polaron impurity problems.As both the electron and phonon baths can be integrated out via the Feynman–Vernon influence functional in the path integral formalism,our method is free of bath discretization error.It can also flexibly work on imaginary time,Keldysh contour,and L-shaped Kadanoff contour.In addition,our method can naturally resolve several long-existing challenges:(i)non-diagonal hybridization function;(ii)measuring multi-time correlations beyond single-particle Green’s functions.We demonstrate the effectiveness and accuracy of our method with extensive numerical examples against analytic solutions,exact diagonalization,and CTQMC.We also perform full-fledged real-time calculations that have never been done before to our knowledge,which could serve as a benchmarking baseline for future method developments.展开更多
基金Supported by the Special Fund of Chinese Central Government for Basic Scientific Research Operations in Commonweal Research Institutes(No.201022001)
文摘A continuous time delay-difference model(CTDDM) has been established that considers continuous time delays of biological processes.The southern Atlantic albacore(Thunnus alalunga) stock is the one of the commercially important tuna population in the marine world.The age structured production model(ASPM) and the surplus production model(SPM) have already been used to assess the albacore stock.However,the ASPM requires detailed biological information and the SPM lacks the biological realism.In this study,we focus on applying a CTDDM to the southern Atlantic albacore(T.alalunga) species,which provides an alternative method to assess this fishery.It is the first time that CTDDM has been provided for assessing the Atlantic albacore(T.alalunga) fishery.CTDDM obtained the 80%confidence interval of MSY(maximum sustainable yield) of(21 510 t,23 118 t).The catch in 2011(24 100 t) is higher than the MSY values and the relative fishing mortality ratio(F_(2011)/F_(MSY)) is higher than 1.0.The results of CTDDM were analyzed to verify the proposed methodology and provide reference information for the sustainable management of the southern Atlantic albacore stock.The CTDDM treats the recruitment,the growth,and the mortality rates as all varying continuously over time and fills gaps between ASPM and SPM in this stock assessment.
基金supported by the Scientific Research Foundation of Sichuan University for Young Teachers,China (GrantNo. 2009SCU11120)
文摘A generalized continuous time random walk model which is dependent on environmental damping is proposed in which the two key parameters of the usual random walk theory： the jumping distance and the waiting time, are replaced by two new ones： the pulse velocity and the flight time. The anomalous diffusion of a free particle which is characterized by the asymptotical mean square displacement （x^2（t）） - t^a is realized numerically and analysed theoretically, where the value of the power index a is in a region of 0 〈 a 〈 2. Particularly, the damping leads to a sub-diffusion when the impact velocities are drawn from a Gaussian density function and the super-diffusive effect is related to statistical extremes, which are called rare-though-dominant events.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11605003 and 11547231
文摘The generalized master equation for the space-time coupled continuous time random walk is derived analytically, in which the space-time coupling is considered through the correlated function 9（t） ～ t^γ, 0 ≤ γ 〈 2, and the probability density function ω（t） of a particle＇s waiting time t follows a power law form for large t： ω（t） ～t^-（1＋α）, 0 〈 α 〈 1. The results indicate that the expressions of the generalized master equation are determined by the correlation exponent 7 and the long-tailed index α of the waiting time. Moreover, the diffusion results obtained from the generalized master equation are in accordance with the previous known results and the numerical simulation results.
基金supported by the region Haute-Normandie Project(Nos.CPER-SER-DDSMRI 2013,2014 and CPER-SER-SEL 2015)
文摘The goal of this paper is to propose a unique control method that permits the evolution of both timed continuous Petri net （TCPN） and T-timed discrete Petri net （T-TDPN） from an initial state to a desired one. Model predictive control （MPC） is a robust control scheme against perturbation and a consistent real-time constraints method. Hence, the proposed approach is studied using the MPC. However, the computational complexity may prevent the use of the MPC for large systems and for large prediction horizons. Then, the proposed approach provides some new techniques in order to reduce the high computational complexity; among them one is taking constant control actions during the prediction.
基金supported by the National Natural Science Foundation of China(62433014,62373287,62573324,62333005,62273255)in part by the International Exchange Program for Graduate Students of Tongji University(4360143306)+3 种基金in part by the Fundamental Research Funds for Central Universities(22120230311)supported by DeutscheForschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy(EXC 2075390740016,468094890)support by the Stuttgart Center for Simulation Science(SimTech)the International Max Planck Research School for Intelligent Systems(IMPRS-IS)for supporting Y.Xie。
文摘Dear Editor,This letter proposes a reinforcement learning-based predictive learning algorithm for unknown continuous-time nonlinear systems with observation loss.Firstly,we construct a temporal nonzero-sum game over predictive control input sequences,deriving multiple optimal predictive control input sequences from its solution.
基金supported by the National Natural Science Foundation of China(Grant Nos.12274131,12347102,12174184)the Natural Science Foundation of Jiangsu Province(Grant No.BK20233001)the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300101)。
文摘A dissipative time crystal is an emergent phase in driven-dissipative quantum many-body systems,characterized by sustained oscillations that break time-translation symmetry spontaneously.Here,we explore nonequilibrium phase transitions in a dissipative Rydberg system driven by a microwave(MW)field and demonstrate their critical sensitivity to high-precision MW sensing.Distinct dynamical regimes are identified,including monostable,bistable,and oscillatory phases under mean-field coupling.Unlike single-particle detection—where the beating signal decays linearly with MW field strength—the time crystalline phase exhibits high sensitivity to MW perturbations,with rapid,discontinuous frequency switching near the monostable-oscillatory boundary.The abrupt transition is rooted in spontaneous symmetry breaking in time and is fundamentally insensitive to the background noise.On this basis,a minimum detectable MW field strength on the order of 1 nV/cm is achieved by leveraging this sensitivity.Our results establish a framework for controlling time crystalline phases with external fields and advance MW sensing through many-body effects.
基金Project supported by the National Science and Technology Major Projects,China(No.2010ZX03006-003-02)
文摘A wide bandwidth continuous time sigma delta ADC is implemented in 130 nm CMOS. A detailed nonidealities analysis （excess loop delay, clock jitter, finite gain and GBW, comparator offset and DAC mismatch） is performed developed in Matlab/Simulink. This design is targeted for wide bandwidth applications such as video or wireless base-stations. A third-order continuous time sigma delta modulator comprises a third-order RC operational- amplifier-based loop filter and 3-bit internal quantizer operated at 512 MHz clock frequency. The sigma delta ADC achieves 60 dB SNR and 59.3 dB SNDR over a 16-MHz signal band at an OSR of 16. The power consumption of the CT sigma delta modulator is 22 mW from the 1.2-V supply.
基金supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciencessupported by the Royal Society Newton International Fellowship and the EU-funded Hungarian(Grant No.EFOP-3.6.1-16-2016-00008)。
文摘Under a first order moment condition on the immigration mechanism,we show that an appropriately scaled supercritical and irreducible multi-type continuous state and continuous time branching process with immigration(CBI process)converges almost surely.If an x log(x)moment condition on the branching mechanism does not hold,then the limit is zero.If this x log(x)moment condition holds,then we prove L1 convergence as well.The projection of the limit on any left non-Perron eigenvector of the branching mean matrix is vanishing.If,in addition,a suitable extra power moment condition on the branching mechanism holds,then we provide the correct scaling for the projection of a CBI process on certain left non-Perron eigenvectors of the branching mean matrix in order to have almost sure and L1 limit.Moreover,under a second order moment condition on the branching and immigration mechanisms,we prove L2 convergence of an appropriately scaled process and the above-mentioned projections as well.A representation of the limits is also provided under the same moment conditions.
文摘A new mixed-integrator-based bi-quad cell is proposed. An alternative synthesis mechanism of complex poles is proposed compared with source-follower-based bi-quad cells which is designed applying the positive feedback technique. Using the negative feedback technique to combine different integrators, the proposed bi-quad cell synthesizes complex poles for designing a continuous time filter. It exhibits various advantages including compact topology, high gain, no parasitic pole, no CMFB circuit, and high capability. The fourth-order Butterworth lowpass filter using the proposed cells has been fabricated in 0.18μm CMOS technology. The active area occupied by the filter with test buffer is only 200 × 170 μm^2. The proposed filter consumes a low power of 201 μW and achieves a 68.5 dB dynamic range.
基金The authors would like to thank the referees for their careful reading and helpful comments that improved the quality of the paper. This work was supported by the National Natural Science Foundation of China （Grant No. 11326175）, the Natural Science Foundation of Zhejiang Province （Nos. LQ14A010012, LY15A010019）, the Natural Science Foundation of 3iangsu Higher Education Institution of China （No. 14KJB110023）, and the Research Foundation of SUST.
文摘We study the asymptotic relation among the maximum of continuous weakly and strongly dependent stationary Gaussian process, the maximum of this process sampled at discrete time points, and the partial sum of this process. It is shown that these two extreme values and the sum are asymptotically independent if the grid of the discrete time points is sufficiently sparse and the Gaussian process is weakly dependent, and asymptotically dependent if the grid points are Pickands grids or dense grids.
基金Supported in part by the National Natural Science Foundation of China under Grant No.11671115 the Natural Science Foundation of Zhejiang Province under Grant No.LY14A010025
文摘A continuous time random walk is a random walk subordinated to a renewal process used in physics to model anomalous diffusion. In this paper, we establish a Chung-type law of the iterated logarithm for continuous time random walk with jumps and waiting times in the domains of attraction of stable laws.
基金Supported by NSFC(Grant Nos.11626245 and 11571043)
文摘For the continuous time Markov chain with transition function P（t） on Z d ＋ , we give the necessary and sufficient conditions for the existence of its Siegmund dual with transition function P - （t）. If Q, the q-matrix of P（t）, is uniformly bounded, we show that the Siegmund dual relation can be expressed directly in terms of q-matrices, and a sufficient condition under which the Q-function is the Siegnmnd dual of some Q-function is also given.
文摘The present paper aims to show the impact of continuous time calculation on life insurance pricing and reserving in the Algerian context. The discrete time approach allows insurance companies to facilitate calculation process but with less accuracy. This approach implies constancy of death quotients during a year. However, the death risk is a continuous function in time. For more accuracy and equity in pricing, calculation needs to consider the exact dates of different payments and also a continuous capitalization process. This gives more adequate premium with fewer hypotheses. This work shows how insurers can propose more adequate pricing using the same actuarial life table.
基金This paper was prepared with the support of the National Youth Science Foundation
文摘This paper deals with the continuous time Markov decision programming (briefly CTMDP) withunbounded reward rate.The economic criterion is the long-run average reward. To the models withcountable state space,and compact metric action sets,we present a set of sufficient conditions to ensurethe existence of the stationary optimal policies.
文摘This paper deals with a stochastic representation of the rainfall process. The analysis of a rainfall time series shows that cumulative representation of a rainfall time series can be modeled as a non-Gaussian random walk with a log-normal jump distribution and a time-waiting distribution following a tempered a-stable probability law. Based on the random walk model, a fractional Fokker-Planck equation （FFPE） with tempered a-stable waiting times was obtained. Through the comparison of observed data and simulated results from the random walk model and FFPE model with tempered a-stable waiting times, it can be concluded that the behavior of the rainfall process is globally reproduced, and the FFPE model with tempered a-stable waiting times is more efficient in reproducing the observed behavior.
文摘In this paper, we set up continuous time model with Poisson Process to analyze demand of investment-oriented life insurance. Individual life time is assumed random, and he is received fixed income, investment-oriented life insurance is an important financial asset under this model. Dynamic programming is applied to analyze this problem. The optimal explicit solutions are obtained in the case of CRRA utilities, and draw its demand curve with numerical simulation.
文摘BACKGROUND Stroke is the leading cause of adult lifelong disability worldwide.A stroke is an acute cerebrovascular disease with a variety of causes and corresponding clinical symptoms.Around 75%of surviving stroke patients experience impaired nerve function,and some suffer from traumatic fractures,which can lead to special care needs.AIM To determine the effect of timing theory continuous care,with resistance training,on the rehabilitation and mental health of caregivers and stroke patients with traumatic fractures.METHODS Between January 2017 to March 2021,we selected 100 hospital admissions with post-stroke hemiplegia complicated with a traumatic fracture.Two participant groups were created:(1)Control group:given resistance training;and(2)Observation group:given timing theory continuous care combined with resistance training.The degree of satisfaction and differences in bone and phosphorus metabolism indexes between the two groups were compared.The self-perceived burden scale(SPBS)and caregiver burden questionnaire were used to evaluate the psychological health of patients and caregivers.The Harris hip function score,ability of daily living(ADL)scale,and global quality of life questionnaire(GQOL-74)were used to evaluate hip function,ability of daily living,and quality of life.RESULTS Data were collected prior to and after intervention.Alkaline phosphatase(ALP),osteocalcin,and vitamin D3 in the observation group and control group increased after intervention(P<0.05),and carboxy-terminal peptide of type I collagenβSpecial sequence(β-CTX)decreased(P<0.05).ALP and osteocalcin in the observation group were higher than in the control group(P<0.05).There was no significant difference inβ-CTX and vitamin D3 between the two groups(P>0.05).The SPBS score of the observation group was lower and the ADL score was higher than the control group.The burden score was lower and the Harris hip function and GQOL-74 scores were higher than that of the control group(P<0.05).The observation group’s satisfaction rating was 94.00%,which was higher than the rating from the control group(P<0.05).CONCLUSION Timing theory continuous nursing with resistance training can reduce hip dysfunction in stroke patients with a traumatic fracture and enhance quality of life and mental health of patients and caregivers.
基金funded by the Swiss National Science Foundation(SNF 200020_182084).
文摘Mediterranean forest communities are particularly diverse but at risk due to their sensitivity to global warming.Understanding the long-term vulnerability of Mediterranean vegetation to climate change is crucial for conservation and management purposes.Studies on past changes of forest communities in response to climate change at ecologically meaningful resolutions(i.e.,decadal time scales) are therefore essential,but still very rare.The Holocene thermal maximum(HTM;ca.10,000-5,000 cal years before the present(BP)) may be used to study species and community responses to warmer conditions than during recent decades.We performed highresolution multiproxy palaeoecological analyses on sediments from crater Lake Mezzano in central Italy to reconstruct vegetation,diversity,and fire dynamics between 8,450 and 7,050 cal years BP.Ordination,crosscorrelation,and species-response analyses were used to investigate the response of Mediterranean forest communities to HTM climate warming,human impact,and fire.Vegetational changes prior to 7,450 cal years BP were driven by climate.Fagus sylvatica spread into mixed deciduous oak forests during the Early Holocene in response to declining seasonality(cooler summers and warmer winters).Subsequently,Fagus sylvatica declined and evergreen Quercus ilex expanded after 8,200 cal years BP when the climate became warmer.Although reduced,Fagus sylvatica remained important together with deciduous oaks.The co-existence of Fagus sylvatica and evergreen Quercus forests is extremely rare today.Human impact significantly affected forest vegetation after7,450 cal years BP,when Neolithic agricultural activities became important,ultimately extirpating these special communities but fostering the overall biodiversity.However,their past occurrence in several central Italian calderas during the HTM suggests that these environments provided habitats that permitted the thriving of cooltemperate forests of Fagus sylvatica under mesomediterranean conditions,with summers ca.1-2℃ warmer than today.Cool and moist calderas may thus become increasingly important for maintaining Mediterranean mesophilous forest species under global warming conditions.
基金supported by the Preeminent Youth Team Project of Guangdong Provincial Natural Science Foundation(Grant No.2024B1515040008)the National Natural Science Foundation of China(Grant No.62173112)+3 种基金the Shenzhen Science and Technology Program(Grant No.RCJC20210609104400005)the Science Center Program of National Natural Science Foundation of China(Grant No.62188101)the Joint Funds of the National Natural Science Foundation of China(Grant No.U2013203)the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2023051)。
文摘In the analysis and design for linear systems in the form of state space,it is undisputed that state responses play a fundamentally important role.For continuous-time linear time-invariant(CT-LTI)systems,the well-known result is that the state responses are given in terms of matrix exponential functions[1].For discrete-time linear time-invariant(DT-LTI)systems,the state responses are expressed in terms of matrix power functions[1].
基金supported by the National Natural Science Foundation of China(Grant No.12104328)。
文摘The polaron problem is a very old problem in condensed matter physics that dates back to the thirties,but still remains largely unsolved today,especially when electron–electron interaction is taken into consideration.The presence of both electron–electron and electron–phonon interactions in the problem invalidates most existing numerical methods,which are either computationally too expensive or simply intractable.The continuous-time quantum Monte Carlo(CTQMC)methods could tackle this problem,but they are only effective on the imaginarytime axis.In this work,we present a method based on tensor networks and the path integral formalism to solve polaron impurity problems.As both the electron and phonon baths can be integrated out via the Feynman–Vernon influence functional in the path integral formalism,our method is free of bath discretization error.It can also flexibly work on imaginary time,Keldysh contour,and L-shaped Kadanoff contour.In addition,our method can naturally resolve several long-existing challenges:(i)non-diagonal hybridization function;(ii)measuring multi-time correlations beyond single-particle Green’s functions.We demonstrate the effectiveness and accuracy of our method with extensive numerical examples against analytic solutions,exact diagonalization,and CTQMC.We also perform full-fledged real-time calculations that have never been done before to our knowledge,which could serve as a benchmarking baseline for future method developments.
