Single fiber pull-out testing was conducted to study the origin of the functional responses to loading of carbon fiber reinforced cement-based composites. The variation of electrical resistance with the bonding force ...Single fiber pull-out testing was conducted to study the origin of the functional responses to loading of carbon fiber reinforced cement-based composites. The variation of electrical resistance with the bonding force on the fiber-matrix interface was measured. Single fiber electromechanical testing was also conducted by measuring the electrical resistance under static tension. Comparison of the results shows that the resistance increasing during single fiber pull-out is mainly due to the changes at the interface. The conduction mechanism of the composite can be explained by the tunneling model. The interfacial stress causes the deformation of interfacial structure and the interfacial debonding, which have influences on the tunneling effect and result in the change of resistance.展开更多
For food chain system with three populations,direct predation is the basic interaction between species.Different species often have different predation functional responses,so a food chain system with Holling-II respo...For food chain system with three populations,direct predation is the basic interaction between species.Different species often have different predation functional responses,so a food chain system with Holling-II response for middle predator and Beddinton-DeAngelis response for top predator is proposed.Apart from direct predation,predator population can significantly impact the survival of prey population by inducing the prey's fear,but the impact often possesses a time delay.This paper is concentrated to explore how the fear and time delay affect the system stability and the species persistence.By use of Lyapunov functional method and bifurcation theory,the positiveness and boundedness of solutions,local and global behavior of species,the system stability around the equilibrium states and various kinds of bifurcation are investigated.Numerically,some simulations are carried out to validate the main findings and the critical values of the bifurcation parameters of fear and conversion rate are obtained.It is observed that fear and delay can not only stabilize,but also destabilize the system,which depends on the magnitude of the fear and delay.The system varies from unstable to stable due to the continuous increase of the prey's fear by middle predator.Small fear induced by top predator or small delay of the prey's fear can stabilize the system,while they are sufficiently large,the system stability is to be destroyed.Simultaneously,the conversion rate can also change the stability and even make the species to be extinct.Some rich dynamics like multiple stabilities and various types of bistability behaviors are also exhibited,which results in the convergence of the species from one stable equilibrium to another.展开更多
In this paper, we study a modified Leslie-Gower predator-prey model with Smith growth subject to homogeneous Neumann boundary condition, in which the functional response is the Crowley-Martin functional response term....In this paper, we study a modified Leslie-Gower predator-prey model with Smith growth subject to homogeneous Neumann boundary condition, in which the functional response is the Crowley-Martin functional response term. Firstly, for ODE model, the local stability of equilibrium point is given. And by using bifurcation theory and selecting suitable bifurcation parameters, we find many kinds of bifurcation phenomena, including Transcritical bifurcation and Hopf bifurcation. For the reaction-diffusion model, we find that Turing instability occurs. Besides, it is proved that Hopf bifurcation exists in the model. Finally, numerical simulations are presented to verify and illustrate the theoretical results.展开更多
The study of predator-prey interactions is commonly analyzed using functional responses to gain an understanding of predation patterns and the impact they have on prey populations.Despite this,little is known about pr...The study of predator-prey interactions is commonly analyzed using functional responses to gain an understanding of predation patterns and the impact they have on prey populations.Despite this,little is known about predator-prey systems with multiple prey species in sites near the equator.Here we studied the functional response of cougars(Puma concolor)in relation to their main prey,armadillo(Dasypus novemcinctus),coati(Nasua narica)and white-tailed deer(Odocoileus virginianus).Between 2004 and 2010,cougar scats were collected along 5 transects to estimate the consumption of different prey species.A relative abundance index(RAI)was calculated for each prey species and cougar using 18 camera traps.We compared Holling type I,II and III functional response models to determine patterns in prey consumption based on the relative abundance and biomass of each prey species consumed.The 3 main prey species comprised 55%(armadillo),17%(coati)and 8%(white-tailed deer)of the diet.Type I and II functional responses described consumption of the 2 most common prey species armadillos and coati similarly well,while a type I response best characterized consumption of white-tailed deer.A negative correlation between the proportions of armadillo versus coati and white-tailed deer biomass in cougar scats suggests switching to consume alternative prey,confirming high foraging plasticity of this carnivore.This work represents one of the few studies to compare functional responses across multiple prey species,combined with evidence for prey-switching at low densities of preferred prey.展开更多
In complex feed structures, there exist main chemical functional groups which are associated with nutrient utilization and availability and functionality. Each functional group has unique molecular structure therefore...In complex feed structures, there exist main chemical functional groups which are associated with nutrient utilization and availability and functionality. Each functional group has unique molecular structure therefore produce unique molecular vibration spectral profile. Feed processing has been used to improve nutrient utilization for many years. However, to date, there was little study on processing-induced changes of feed intrinsic structure and functional groups on a molecular basis within intact tissue. This is because limited research technique is available to study inherent structure on a molecular basis. Recently bioanalytical techniques： such as Synchrotron Infrared Microspectroscopy as well as Diffuse Reflectance Infrared Fourier Transform molecular spectroscopy have been developed. These techniques enable to detect molecular structure change within intact tissues. These techniques can prevent destruction or alteration of the intrinsic protein structures during processing for analysis. However, these techniques have not been used in animal feed and nutrition research. The objective of this review was show that with the advanced technique, sensitivity and responses of functional groups to feed processing on a molecular basis could be detected in my research team. These functional groups are highly associated with nutrient utilization in animals.展开更多
Allam and Tantawy [1] presented an analytical solu- tion for stress distribution and perturbations of the magnetic field vector in FGM hollow structures made from viscoelas- tic composite materials .While studying thi...Allam and Tantawy [1] presented an analytical solu- tion for stress distribution and perturbations of the magnetic field vector in FGM hollow structures made from viscoelas- tic composite materials .While studying this article, the dis- cusser noticed a confusion in regarding Maxwell＇s electro- magnetic stress expression展开更多
The main purpose of this paper is to explore the existence of positive periodic solutions to impulsive predator-prey systems with type IV functional responses. Sufficient criteria are obtained for the existence of str...The main purpose of this paper is to explore the existence of positive periodic solutions to impulsive predator-prey systems with type IV functional responses. Sufficient criteria are obtained for the existence of strictly positive periodic solutions. The approach is based on a continuation theorem in the coincidence degree theory as well as some prior estimates. This is also the first time that multiple positive periodic solutions are obtained using coincidence degree theory in impulsive ecological systems.展开更多
To investigate the effects of self-memory diffusion on predator-prey models, we consider a predator-prey model with Bazykin functional response of self- memory diffusion. The uniqueness, boundedness, positivity, exist...To investigate the effects of self-memory diffusion on predator-prey models, we consider a predator-prey model with Bazykin functional response of self- memory diffusion. The uniqueness, boundedness, positivity, existence and stability of equilibrium point of the model are studied. In this paper, the uniqueness of the solution is discussed under the non-negative initial function and Neumann boundary conditions satisfying a specific space. The boundness of the solution is proved by the comparison principle of parabolic equations, and the positivity of the solution is proved by the strong maximum principle of parabolic equations. Hurwitz criterion and Lyapunov function construction are used to analyze the local stability and global stability of feasible equilibrium points. The results show that the system solution is unique non-negative and bounded. The model is unstable at the trivial equilibrium point E0 and the boundary equilibrium point E1, and the condition of whether the positive equilibrium point E2 is stable under certain conditions is given.展开更多
A predator-prey model with linear capture term Holling-II functional response was studied by using differential equation theory. The existence and the stabilities of non-negative equilibrium points of the model were d...A predator-prey model with linear capture term Holling-II functional response was studied by using differential equation theory. The existence and the stabilities of non-negative equilibrium points of the model were discussed. The results show that under certain limited conditions, these two groups can maintain a balanced position, which provides a theoretical reference for relevant departments to make decisions on ecological protection.展开更多
Cement density monitoring plays a vital role in evaluating the quality of cementing projects,which is of great significance to the development of oil and gas.However,the presence of inhomogeneous cement distribution a...Cement density monitoring plays a vital role in evaluating the quality of cementing projects,which is of great significance to the development of oil and gas.However,the presence of inhomogeneous cement distribution and casing eccentricity in horizontal wells often complicates the accurate evaluation of cement azimuthal density.In this regard,this paper proposes an algorithm to calculate the cement azimuthal density in horizontal wells using a multi-detector gamma-ray detection system.The spatial dynamic response functions are simulated to obtain the influence of cement density on gamma-ray counts by the perturbation theory,and the contribution of cement density in six sectors to the gamma-ray recorded by different detectors is obtained by integrating the spatial dynamic response functions.Combined with the relationship between gamma-ray counts and cement density,a multi-parameter calculation equation system is established,and the regularized Newton iteration method is employed to invert casing eccentricity and cement azimuthal density.This approach ensures the stability of the inversion process while simultaneously achieving an accuracy of 0.05 g/cm^(3) for the cement azimuthal density.This accuracy level is ten times higher compared to density accuracy calculated using calibration equations.Overall,this algorithm enhances the accuracy of cement azimuthal density evaluation,provides valuable technical support for the monitoring of cement azimuthal density in the oil and gas industry.展开更多
Hyper-and multi-spectral image fusion is an important technology to produce hyper-spectral and hyper-resolution images,which always depends on the spectral response function andthe point spread function.However,few wo...Hyper-and multi-spectral image fusion is an important technology to produce hyper-spectral and hyper-resolution images,which always depends on the spectral response function andthe point spread function.However,few works have been payed on the estimation of the two degra-dation functions.To learn the two functions from image pairs to be fused,we propose a Dirichletnetwork,where both functions are properly constrained.Specifically,the spatial response function isconstrained with positivity,while the Dirichlet distribution along with a total variation is imposedon the point spread function.To the best of our knowledge,the neural network and the Dirichlet regularization are exclusively investigated,for the first time,to estimate the degradation functions.Both image degradation and fusion experiments demonstrate the effectiveness and superiority of theproposed Dirichlet network.展开更多
By using the continuation theorem of coincidence theory, the existence of a positive periodic solution for a two patches competition system with diffusion and time delay and functional responsex [FK(W1*3/4。*2/3]...By using the continuation theorem of coincidence theory, the existence of a positive periodic solution for a two patches competition system with diffusion and time delay and functional responsex [FK(W1*3/4。*2/3]′ 1 (t)=x 1(t)a 1(t)-b 1(t)x 1(t)-c 1(t)y(t)1+m(t)x 1(t)+D 1(t)[x 2(t)-x 1(t)], x [FK(W1*3/4。*2/3]′ 2 (t)=x 2(t)a 2(t)-b 2(t)x 2(t)-c 2(t)∫ 0 -τ k(s)x 2(t+s) d s+D 2(t)[x 1(t)-x 2(t)], y′(t)=y(t)a 3(t)-b 3(t)y(t)-c 3(t)x 1(t)1+m(t)x 1(t)is established, where a i(t),b i(t),c i(t)(i=1,2,3),m(t) and D i(t)(i=1,2) are all positive periodic continuous functions with period w >0, τ is a nonnegative constant and k(s) is a continuous nonnegative function on [- τ ,0].展开更多
Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperat...Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperature on parasitoid preference of female Anagrus nilaparvatae Pang et Wang （Hymenoptera：Mymaridae） to the eggs of whitebacked planthopper （WBPH）, Sogatella furcifera Horváth and brown planthopper （BPH）, Nilaparvata lugens Stl to build a composite model describing changes in parasitic response along a temperature gradient （18, 22, 26, 30, 34°C）. The results showed that attack responses of A. nilaparvatae on WBPH and BPH were the best described by a Type II functional response. The two parameters, attack rates （a） and handling times （Th）, of A. nilaparvatae to both eggs were influenced by the temperature. The maximum attack rates to WBPH （1.235） and BPH （1.049） were at 26 and 34°C, respectively, and the shortest handling times to WBPH （0.063） and BPH （0.057） were at 30 and 26°C, respectively. However, the optimal temperature for parasitic efficiency of A. nilaparvatae to WBPH and BPH eggs was both at 26°C, which showed that the present microclimate temperature of the habitat in the paddyfield was beneficial to A. nilaparvatae and indicated that parasitic efficiency of A. nilaparvatae would be impaired by global warming.展开更多
An efficient generic static headspace gas chromatography （HSGC） method was developed, optimized and validated for the routine determination of several residual solvents （RS） in drug substance, using a strategy wit...An efficient generic static headspace gas chromatography （HSGC） method was developed, optimized and validated for the routine determination of several residual solvents （RS） in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide （DMSO） was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chroma- tograph from Agilent Model 6890 equipped with flame ionization detector （FID） and a DB-624 （30 m × 0.53 mm i.d., 3.00 μm film thickness） column was used. The inlet split ratio was 5：1. The influ- encing factors in the chromatographic separation of the analytes were determined through a fractional factorial experimental design. Significant variables： the initial temperature （IT）, the final temperature （FT） of the oven and the carrier gas flow rate （F） were optimized using a central composite design. Response transformation and desirability function were applied to find out the optimal combination of the chromatographic variables to achieve an adequate resolution of the analytes and short analysis time. These conditions were 30 ℃ for IT, 158 ℃ for FT and 1.90 mL/min for F. The method was proven to be accurate, linear in a wide range and very sensitive for the analyzed solvents through a comprehensive validation according to the ICH guidelines.展开更多
This paper deals with the questio n of global stability of the positive locally asymptotically stable equilibrium in a class of predator\|prey system of Gause\|typ e with Holling Ⅲ functional response. The Dulac'...This paper deals with the questio n of global stability of the positive locally asymptotically stable equilibrium in a class of predator\|prey system of Gause\|typ e with Holling Ⅲ functional response. The Dulac's criterion is applied and lia punov functions are constructed to establish the global stability.展开更多
The effect of a protection zone on a diffusion predator-prey model with Ivlev-type functional response is considered.We discuss the existence and non-existence of positive steady state solutions by using the bifurcati...The effect of a protection zone on a diffusion predator-prey model with Ivlev-type functional response is considered.We discuss the existence and non-existence of positive steady state solutions by using the bifurcation theory.It is shown that the protection zone for prey has beneficial effects on the coexistence of the two species when the growth rate of predator is positive.Moreover,we examine the dependence of the coexistence region on the efficiency of the predator capture of the prey and the protection zone.展开更多
The main purpose of this paper is to study the persistence of the general multispecies competition predator-pray system with Holling Ⅲ type functional response. In this system, the competition among predator species ...The main purpose of this paper is to study the persistence of the general multispecies competition predator-pray system with Holling Ⅲ type functional response. In this system, the competition among predator species and among prey species are simultaneously considered. By using the comparison theory and qualitative analysis, the sufficient conditions for uniform strong persistence are obtained.展开更多
In this study, the impulsive predator-prey dynamic systems on time scales calculus are studied. When the system has periodic solution is investigated, and three different conditions have been found, which are necessar...In this study, the impulsive predator-prey dynamic systems on time scales calculus are studied. When the system has periodic solution is investigated, and three different conditions have been found, which are necessary for the periodic solution of the predator-prey dynamic systems with Beddington-DeAngelis type functional response. For this study the main tools are time scales calculus and coincidence degree theory. Also the findings are beneficial for continuous case, discrete case and the unification of both these cases. Additionally, unification of continuous and discrete case is a good example for the modeling of the life cycle of insects.展开更多
In recent years,rumor spreading has caused widespread public panic and affected the whole social harmony and stability.Consequently,how to control the rumor spreading effectively and reduce its negative influence urge...In recent years,rumor spreading has caused widespread public panic and affected the whole social harmony and stability.Consequently,how to control the rumor spreading effectively and reduce its negative influence urgently needs people to pay much attention.In this paper,we mainly study the near-optimal control of a stochastic rumor spreading model with Holling II functional response function and imprecise parameters.Firstly,the science knowledge propagation and the refutation mechanism as the control strategies are introduced into a stochastic rumor spreading model.Then,some sufficient and necessary conditions for the near-optimal control of the stochastic rumor spreading model are discussed respectively.Finally,through some numerical simulations,the validity and availability of theoretical analysis is verified.Meanwhile,it shows the significance and effectiveness of the proposed control strategies on controlling rumor spreading,and demonstrates the influence of stochastic disturbance and imprecise parameters on the process of rumor spreading.展开更多
This paper investigates the existence of periodic solutions of a three-species food-chain diffusive system with Beddington-DeAngelis functional responses and time delays in a two-patch environment on time scales. By u...This paper investigates the existence of periodic solutions of a three-species food-chain diffusive system with Beddington-DeAngelis functional responses and time delays in a two-patch environment on time scales. By using a continuation theorem based on coincidence degree theory, we obtain sufficient criteria for the existence of periodic solutions for the system. Moreover, when the time scale T is chosen as R or Z, the existence of the periodic solutions of the corresponding continuous and discrete models follows. Therefore, the method is unified to provide the existence of the desired solutions for continuous differential equations and discrete difference equations.展开更多
基金the National Natural Science Foundation of China Key Project(No.50238040)
文摘Single fiber pull-out testing was conducted to study the origin of the functional responses to loading of carbon fiber reinforced cement-based composites. The variation of electrical resistance with the bonding force on the fiber-matrix interface was measured. Single fiber electromechanical testing was also conducted by measuring the electrical resistance under static tension. Comparison of the results shows that the resistance increasing during single fiber pull-out is mainly due to the changes at the interface. The conduction mechanism of the composite can be explained by the tunneling model. The interfacial stress causes the deformation of interfacial structure and the interfacial debonding, which have influences on the tunneling effect and result in the change of resistance.
基金funded by the National Natural Science Foundation of China with number 11861027.
文摘For food chain system with three populations,direct predation is the basic interaction between species.Different species often have different predation functional responses,so a food chain system with Holling-II response for middle predator and Beddinton-DeAngelis response for top predator is proposed.Apart from direct predation,predator population can significantly impact the survival of prey population by inducing the prey's fear,but the impact often possesses a time delay.This paper is concentrated to explore how the fear and time delay affect the system stability and the species persistence.By use of Lyapunov functional method and bifurcation theory,the positiveness and boundedness of solutions,local and global behavior of species,the system stability around the equilibrium states and various kinds of bifurcation are investigated.Numerically,some simulations are carried out to validate the main findings and the critical values of the bifurcation parameters of fear and conversion rate are obtained.It is observed that fear and delay can not only stabilize,but also destabilize the system,which depends on the magnitude of the fear and delay.The system varies from unstable to stable due to the continuous increase of the prey's fear by middle predator.Small fear induced by top predator or small delay of the prey's fear can stabilize the system,while they are sufficiently large,the system stability is to be destroyed.Simultaneously,the conversion rate can also change the stability and even make the species to be extinct.Some rich dynamics like multiple stabilities and various types of bistability behaviors are also exhibited,which results in the convergence of the species from one stable equilibrium to another.
文摘In this paper, we study a modified Leslie-Gower predator-prey model with Smith growth subject to homogeneous Neumann boundary condition, in which the functional response is the Crowley-Martin functional response term. Firstly, for ODE model, the local stability of equilibrium point is given. And by using bifurcation theory and selecting suitable bifurcation parameters, we find many kinds of bifurcation phenomena, including Transcritical bifurcation and Hopf bifurcation. For the reaction-diffusion model, we find that Turing instability occurs. Besides, it is proved that Hopf bifurcation exists in the model. Finally, numerical simulations are presented to verify and illustrate the theoretical results.
基金We thank the Mexican people for funding the project through CONACYT(101254)and for the scholarship(LSD)214042.
文摘The study of predator-prey interactions is commonly analyzed using functional responses to gain an understanding of predation patterns and the impact they have on prey populations.Despite this,little is known about predator-prey systems with multiple prey species in sites near the equator.Here we studied the functional response of cougars(Puma concolor)in relation to their main prey,armadillo(Dasypus novemcinctus),coati(Nasua narica)and white-tailed deer(Odocoileus virginianus).Between 2004 and 2010,cougar scats were collected along 5 transects to estimate the consumption of different prey species.A relative abundance index(RAI)was calculated for each prey species and cougar using 18 camera traps.We compared Holling type I,II and III functional response models to determine patterns in prey consumption based on the relative abundance and biomass of each prey species consumed.The 3 main prey species comprised 55%(armadillo),17%(coati)and 8%(white-tailed deer)of the diet.Type I and II functional responses described consumption of the 2 most common prey species armadillos and coati similarly well,while a type I response best characterized consumption of white-tailed deer.A negative correlation between the proportions of armadillo versus coati and white-tailed deer biomass in cougar scats suggests switching to consume alternative prey,confirming high foraging plasticity of this carnivore.This work represents one of the few studies to compare functional responses across multiple prey species,combined with evidence for prey-switching at low densities of preferred prey.
基金supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC)SaskCanola Funding+1 种基金Saskatchewan Agricultural Development Fund (ADF)Ministry of Agriculture Strategic Research Chair Fund (Saskatchewan,Canada)
文摘In complex feed structures, there exist main chemical functional groups which are associated with nutrient utilization and availability and functionality. Each functional group has unique molecular structure therefore produce unique molecular vibration spectral profile. Feed processing has been used to improve nutrient utilization for many years. However, to date, there was little study on processing-induced changes of feed intrinsic structure and functional groups on a molecular basis within intact tissue. This is because limited research technique is available to study inherent structure on a molecular basis. Recently bioanalytical techniques： such as Synchrotron Infrared Microspectroscopy as well as Diffuse Reflectance Infrared Fourier Transform molecular spectroscopy have been developed. These techniques enable to detect molecular structure change within intact tissues. These techniques can prevent destruction or alteration of the intrinsic protein structures during processing for analysis. However, these techniques have not been used in animal feed and nutrition research. The objective of this review was show that with the advanced technique, sensitivity and responses of functional groups to feed processing on a molecular basis could be detected in my research team. These functional groups are highly associated with nutrient utilization in animals.
文摘Allam and Tantawy [1] presented an analytical solu- tion for stress distribution and perturbations of the magnetic field vector in FGM hollow structures made from viscoelas- tic composite materials .While studying this article, the dis- cusser noticed a confusion in regarding Maxwell＇s electro- magnetic stress expression
基金National Natural Science Foundation of China(#10671069).
文摘The main purpose of this paper is to explore the existence of positive periodic solutions to impulsive predator-prey systems with type IV functional responses. Sufficient criteria are obtained for the existence of strictly positive periodic solutions. The approach is based on a continuation theorem in the coincidence degree theory as well as some prior estimates. This is also the first time that multiple positive periodic solutions are obtained using coincidence degree theory in impulsive ecological systems.
文摘To investigate the effects of self-memory diffusion on predator-prey models, we consider a predator-prey model with Bazykin functional response of self- memory diffusion. The uniqueness, boundedness, positivity, existence and stability of equilibrium point of the model are studied. In this paper, the uniqueness of the solution is discussed under the non-negative initial function and Neumann boundary conditions satisfying a specific space. The boundness of the solution is proved by the comparison principle of parabolic equations, and the positivity of the solution is proved by the strong maximum principle of parabolic equations. Hurwitz criterion and Lyapunov function construction are used to analyze the local stability and global stability of feasible equilibrium points. The results show that the system solution is unique non-negative and bounded. The model is unstable at the trivial equilibrium point E0 and the boundary equilibrium point E1, and the condition of whether the positive equilibrium point E2 is stable under certain conditions is given.
文摘A predator-prey model with linear capture term Holling-II functional response was studied by using differential equation theory. The existence and the stabilities of non-negative equilibrium points of the model were discussed. The results show that under certain limited conditions, these two groups can maintain a balanced position, which provides a theoretical reference for relevant departments to make decisions on ecological protection.
基金The authors would like to acknowledge the support of the National Natural Science Foundation of China(41974127,42174147).References。
文摘Cement density monitoring plays a vital role in evaluating the quality of cementing projects,which is of great significance to the development of oil and gas.However,the presence of inhomogeneous cement distribution and casing eccentricity in horizontal wells often complicates the accurate evaluation of cement azimuthal density.In this regard,this paper proposes an algorithm to calculate the cement azimuthal density in horizontal wells using a multi-detector gamma-ray detection system.The spatial dynamic response functions are simulated to obtain the influence of cement density on gamma-ray counts by the perturbation theory,and the contribution of cement density in six sectors to the gamma-ray recorded by different detectors is obtained by integrating the spatial dynamic response functions.Combined with the relationship between gamma-ray counts and cement density,a multi-parameter calculation equation system is established,and the regularized Newton iteration method is employed to invert casing eccentricity and cement azimuthal density.This approach ensures the stability of the inversion process while simultaneously achieving an accuracy of 0.05 g/cm^(3) for the cement azimuthal density.This accuracy level is ten times higher compared to density accuracy calculated using calibration equations.Overall,this algorithm enhances the accuracy of cement azimuthal density evaluation,provides valuable technical support for the monitoring of cement azimuthal density in the oil and gas industry.
基金the Postdoctoral ScienceFoundation of China(No.2023M730156)the NationalNatural Foundation of China(No.62301012).
文摘Hyper-and multi-spectral image fusion is an important technology to produce hyper-spectral and hyper-resolution images,which always depends on the spectral response function andthe point spread function.However,few works have been payed on the estimation of the two degra-dation functions.To learn the two functions from image pairs to be fused,we propose a Dirichletnetwork,where both functions are properly constrained.Specifically,the spatial response function isconstrained with positivity,while the Dirichlet distribution along with a total variation is imposedon the point spread function.To the best of our knowledge,the neural network and the Dirichlet regularization are exclusively investigated,for the first time,to estimate the degradation functions.Both image degradation and fusion experiments demonstrate the effectiveness and superiority of theproposed Dirichlet network.
文摘By using the continuation theorem of coincidence theory, the existence of a positive periodic solution for a two patches competition system with diffusion and time delay and functional responsex [FK(W1*3/4。*2/3]′ 1 (t)=x 1(t)a 1(t)-b 1(t)x 1(t)-c 1(t)y(t)1+m(t)x 1(t)+D 1(t)[x 2(t)-x 1(t)], x [FK(W1*3/4。*2/3]′ 2 (t)=x 2(t)a 2(t)-b 2(t)x 2(t)-c 2(t)∫ 0 -τ k(s)x 2(t+s) d s+D 2(t)[x 1(t)-x 2(t)], y′(t)=y(t)a 3(t)-b 3(t)y(t)-c 3(t)x 1(t)1+m(t)x 1(t)is established, where a i(t),b i(t),c i(t)(i=1,2,3),m(t) and D i(t)(i=1,2) are all positive periodic continuous functions with period w >0, τ is a nonnegative constant and k(s) is a continuous nonnegative function on [- τ ,0].
基金supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (200903051 and 200803003)
文摘Understanding the temperature affecting parasitic efficiency is critical to succeed in utilizing parasitoid as natural enemy in pest management. Laboratory studies were carried out to determine the effects of temperature on parasitoid preference of female Anagrus nilaparvatae Pang et Wang （Hymenoptera：Mymaridae） to the eggs of whitebacked planthopper （WBPH）, Sogatella furcifera Horváth and brown planthopper （BPH）, Nilaparvata lugens Stl to build a composite model describing changes in parasitic response along a temperature gradient （18, 22, 26, 30, 34°C）. The results showed that attack responses of A. nilaparvatae on WBPH and BPH were the best described by a Type II functional response. The two parameters, attack rates （a） and handling times （Th）, of A. nilaparvatae to both eggs were influenced by the temperature. The maximum attack rates to WBPH （1.235） and BPH （1.049） were at 26 and 34°C, respectively, and the shortest handling times to WBPH （0.063） and BPH （0.057） were at 30 and 26°C, respectively. However, the optimal temperature for parasitic efficiency of A. nilaparvatae to WBPH and BPH eggs was both at 26°C, which showed that the present microclimate temperature of the habitat in the paddyfield was beneficial to A. nilaparvatae and indicated that parasitic efficiency of A. nilaparvatae would be impaired by global warming.
基金Universidad Nacional del Litoral (Projects CAI+D 2011 No.PI-50120110100025 LI)ANPCyT (Agencia Nacional de Promocin Científica y Tecnolgica,Project PICT 2011-0005) for financial support
文摘An efficient generic static headspace gas chromatography （HSGC） method was developed, optimized and validated for the routine determination of several residual solvents （RS） in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide （DMSO） was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chroma- tograph from Agilent Model 6890 equipped with flame ionization detector （FID） and a DB-624 （30 m × 0.53 mm i.d., 3.00 μm film thickness） column was used. The inlet split ratio was 5：1. The influ- encing factors in the chromatographic separation of the analytes were determined through a fractional factorial experimental design. Significant variables： the initial temperature （IT）, the final temperature （FT） of the oven and the carrier gas flow rate （F） were optimized using a central composite design. Response transformation and desirability function were applied to find out the optimal combination of the chromatographic variables to achieve an adequate resolution of the analytes and short analysis time. These conditions were 30 ℃ for IT, 158 ℃ for FT and 1.90 mL/min for F. The method was proven to be accurate, linear in a wide range and very sensitive for the analyzed solvents through a comprehensive validation according to the ICH guidelines.
基金Supported by the National Natural Science Foundation of China(195 310 70 )
文摘This paper deals with the questio n of global stability of the positive locally asymptotically stable equilibrium in a class of predator\|prey system of Gause\|typ e with Holling Ⅲ functional response. The Dulac's criterion is applied and lia punov functions are constructed to establish the global stability.
基金Supported by the National Natural Science Foundation of China(11761063).
文摘The effect of a protection zone on a diffusion predator-prey model with Ivlev-type functional response is considered.We discuss the existence and non-existence of positive steady state solutions by using the bifurcation theory.It is shown that the protection zone for prey has beneficial effects on the coexistence of the two species when the growth rate of predator is positive.Moreover,we examine the dependence of the coexistence region on the efficiency of the predator capture of the prey and the protection zone.
基金Supported by the National Natural Science Foundation of China (10701020)
文摘The main purpose of this paper is to study the persistence of the general multispecies competition predator-pray system with Holling Ⅲ type functional response. In this system, the competition among predator species and among prey species are simultaneously considered. By using the comparison theory and qualitative analysis, the sufficient conditions for uniform strong persistence are obtained.
文摘In this study, the impulsive predator-prey dynamic systems on time scales calculus are studied. When the system has periodic solution is investigated, and three different conditions have been found, which are necessary for the periodic solution of the predator-prey dynamic systems with Beddington-DeAngelis type functional response. For this study the main tools are time scales calculus and coincidence degree theory. Also the findings are beneficial for continuous case, discrete case and the unification of both these cases. Additionally, unification of continuous and discrete case is a good example for the modeling of the life cycle of insects.
基金Project supported by the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe Project for the Natural Science Foundation of Shanghai,China(Grant No.21ZR1444100)the Project for the National Natural Science Foundation of China(Grant Nos.72174121,71774111,71871144,and 71804047)。
文摘In recent years,rumor spreading has caused widespread public panic and affected the whole social harmony and stability.Consequently,how to control the rumor spreading effectively and reduce its negative influence urgently needs people to pay much attention.In this paper,we mainly study the near-optimal control of a stochastic rumor spreading model with Holling II functional response function and imprecise parameters.Firstly,the science knowledge propagation and the refutation mechanism as the control strategies are introduced into a stochastic rumor spreading model.Then,some sufficient and necessary conditions for the near-optimal control of the stochastic rumor spreading model are discussed respectively.Finally,through some numerical simulations,the validity and availability of theoretical analysis is verified.Meanwhile,it shows the significance and effectiveness of the proposed control strategies on controlling rumor spreading,and demonstrates the influence of stochastic disturbance and imprecise parameters on the process of rumor spreading.
基金Supported by the Foundation for subjects development of Harbin University(No.HXK200716)
文摘This paper investigates the existence of periodic solutions of a three-species food-chain diffusive system with Beddington-DeAngelis functional responses and time delays in a two-patch environment on time scales. By using a continuation theorem based on coincidence degree theory, we obtain sufficient criteria for the existence of periodic solutions for the system. Moreover, when the time scale T is chosen as R or Z, the existence of the periodic solutions of the corresponding continuous and discrete models follows. Therefore, the method is unified to provide the existence of the desired solutions for continuous differential equations and discrete difference equations.
