Tibet Plateau has uplifted greatly in the Late Cenozoic era (Li Jijun et al., 1979; Sun Honglie, 1996; Shi Yafeng et al., 1998). The uplift will unquestionably influence the environment and climate of the plateau in t...Tibet Plateau has uplifted greatly in the Late Cenozoic era (Li Jijun et al., 1979; Sun Honglie, 1996; Shi Yafeng et al., 1998). The uplift will unquestionably influence the environment and climate of the plateau in the same time (such as resulting in the decrease of temperature) and leave some footprint on the contemporary sediments on or around the plateau. So, there must be some persistence component in the environmental and climatic evolution reflected by the geochemical information in the contemporary sediments. TS95, namely Tianshuihai Lake core is at the south frank of West Kunlun Mountain of Tibet Plateau and is suitable for the investigation of the persistence component. Using R/S analysis, Zhou Houyun et al. (1999) have previously calculated the Hurst index H of the three ferric indexes, FeO, Fe\-2O\-3 and ratio of FeO/ Fe\-2O\-3, from TS95. It is found that all these indexes satisfy Hurst law and they all are greater than 0 5, which means that there are some long run dependencies\|persistence component in the climatic and environmental evolution around Tianshuihai Lake area. This is in accordance with previous work by Yu Suhua et al. (1996). In this paper, the authors use the same method to do some R/S analysis on the other two climatic proxies of TS95, δ 13 C and δ 18 O, which are more suitable than the three ferric indexes to be climatic and environmental proxies. It is found that both the δ 13 C and δ 18 O satisfy Hurst law very well with H δ 13 C =0 875 and H δ 18 O =894, which suggests stronger persistence than the three ferric indexes.展开更多
The paper researched effect of adjuvants on activity and persistence of soil-applied herbicide Anwei.There were five adjuvants (fertility, Q7, oil, anionic and nonionic surfactants) in the experiment. We explored the ...The paper researched effect of adjuvants on activity and persistence of soil-applied herbicide Anwei.There were five adjuvants (fertility, Q7, oil, anionic and nonionic surfactants) in the experiment. We explored the influence of adjuvants on activity and persistence of Anwei by field trial. The results indicated that Q7, oil, anionic surfactant can increased activity of Anwei, and can lengthened its persistence for about five days.展开更多
A stochastic epidemic model with two age groups is established in this study,in which the susceptible(S),the exposed(E),the infected(I),the hospitalized(H)and the recovered(R)are involved within the total population,t...A stochastic epidemic model with two age groups is established in this study,in which the susceptible(S),the exposed(E),the infected(I),the hospitalized(H)and the recovered(R)are involved within the total population,the aging rates between two age groups are set to be constant.The existence-and-uniqueness of global positive solution is firstly showed.Then,by constructing several appropriate Lyapunov functions and using the high-dimensional Itô’s formula,the sufficient conditions for the stochastic extinction and stochastic persistence of the exposed individuals and the infected individuals are obtained.The stochastic extinction indicator and the stochastic persistence indicator are less-valued expressions compared with the basic reproduction number.Meanwhile,the main results of this study are modified into multi-age groups.Furthermore,by using the surveillance data for Fujian Provincial Center for Disease Control and Prevention,Fuzhou COVID-19 epidemic is chosen to carry out the numerical simulations,which show that the age group of the population plays the vital role when studying infectious diseases.展开更多
Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent lumine...Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent luminescent material applications.At present,YAGG:Ce^(3+),Cr^(3+)powders exhibit good persistent performance,but their persistent performance of ceramics still needs to be further improved to meet the new requirements.In this work,(Y_(0.998)Ce_(0.002))_(3)(Al_(1-x)Cr_(x))_(2)Ga_(3)O_(12) ceramics with different Cr^(3+)doping concentrations were prepared by solid-state reaction,including air pre-sintering,hot isostatic pressing(HIP)post-treatment and air annealing,to investigate the effects of Cr^(3+)doping concentration on the microstructure,optical properties and persistent performance of the ceramics.The results showed that as the doping concentration of Cr^(3+)increased from 0.025%to 0.2%(in atom),no significant effect of Cr^(3+)concentration on the morphology of pre-sintered ceramics or HIP post-treatment ceramics was observed,but the in-line transmittance gradually increased while the persistent performance gradually decreased.Among them,YAGG:Ce^(3+),Cr^(3+)ceramics doped with 0.025%Cr^(3+)showed the strongest initial luminescence intensity exceeding 6055 mcd/m^(2) and a persistent time of 1030 min after air pre-sintering combined with HIP post-treatment and air annealing.By optimizing the Cr^(3+)doping concentration and the fabrication process,the persistent luminescence(PersL)performance of the YAGG:Ce^(3+),Cr^(3+)ceramics was obviously improved.展开更多
Anisotropic strength and deformability of the rock mass with non-persistent joints are governed by cracking process of the rock bridges. The dependence of cracking process of jointed rock masses on the two important g...Anisotropic strength and deformability of the rock mass with non-persistent joints are governed by cracking process of the rock bridges. The dependence of cracking process of jointed rock masses on the two important geometrical parameters, joint orientation and joint persistence, was studied systematically by carrying out a series of uniaxial compression tests on gypsum specimens with regularly arranged multiple parallel pre-existing joints. According to crack position, mechanism and temporal sequence, seven types of crack initiations and sixteen types of crack coalescences, were identified. It was observed that both tensile cracks and shear cracks can emanate from the pre-existing joints as well as the matrix. Vertical joints were included and coplanar tensile cracks initiation and coalescence were observed accordingly. For specimen with joint inclination angle ,8=75~, it was found that collinear joints can be linked not only by coplanar shear cracks but also by mixed tensile-shear cracks, and that a pair of them can form a small rotation block. Seven failure modes, including axial cleavage, crushing, crushing and rotation of new blocks, stepped failure, stepped failure and rotation of new blocks, shear failure along a single plane and shear failure along multiple planes, were observed. These modes shift gradually in accordance with the combined variation of joint orientation and joint persistence. It is concluded that cracking process and failure modes are more strongly affected by joint orientation than by joint persistence, especially when joint inclination angle is larger than 45~. Finally, variations of macroscopic mechanical behaviors with the two geometrical parameters, such as patterns of the complete axial stress-axial strain curves, peak strength and elastic modulus, are summarized and their mechanisms are successfully explained according to their different cracking process.展开更多
In the present paper,the nonautonomous two-species Predator-Prey models with diffusion are considered. Prey species can diffuse between two patches, while the predator species is confined to one patch and cannot diffu...In the present paper,the nonautonomous two-species Predator-Prey models with diffusion are considered. Prey species can diffuse between two patches, while the predator species is confined to one patch and cannot diffuse. It is proved that if the coefficients satisfy certain inequalities,then the system can be made persistent and have a strictly positive periodic orbit which is glotally asymptotically stable.展开更多
The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlin...The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlinear transformation. Moreover, it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold. Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.展开更多
The long-term reclamation-induced ground subsidence in Macao, a coastal city of southern China was investigated. Persistent scatterer interferometry (PSI) technique was applied to retrieve the deformation rate in Maca...The long-term reclamation-induced ground subsidence in Macao, a coastal city of southern China was investigated. Persistent scatterer interferometry (PSI) technique was applied to retrieve the deformation rate in Macao during the period from April 2003 to August 2010 with a total of 41 scenes of descending ASAR data sets. The PSI-retrieved results show a relatively stable pattern in Macao Peninsula, Taipa Island and Coloane Island, with an average subsidence velocity of -3 mm/a. In contrast, relatively large subsidence rates are highlighted in Cotai area, a new reclamation land in 1990s, in which an average subsidence velocity is about -10 mm/a. A consistent relationship between the PSI results and the leveling measurements indicate that this PSI technique is an effective tool to monitor the reclamation-induced ground subsidence with a high accuracy and adequate spatial details. Accordingly, the valuable ground subsidence results generated by PSI can be used not only for early detection and remedial activities of potential settlement of building, but also for helping the local government to formulate regional sustainable development planning and decision-making in disaster prevention and mitigation.展开更多
The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedfo...The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedforward and feedbaek optimal controller is presented. The condition of existence and uniqueness of the control law is given. The disturbanee observer is proposed to make the feedforward control law realizable physically. Simulation results demonstrate that the feedforward and feedbaek optimal control law is more effective and robust than the elassical state feedbaek control law with respect to external disturbanees.展开更多
An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is c...An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear two- point boundary value （TPBV） problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.展开更多
Myoblast-mediated gene transfer approach has agreat potential to be developed into a durable genetherapy method for various diseases. To increase theexpression level of human factor Ⅸ (hFⅨ) in musclecells, we constr...Myoblast-mediated gene transfer approach has agreat potential to be developed into a durable genetherapy method for various diseases. To increase theexpression level of human factor Ⅸ (hFⅨ) in musclecells, we constructed a series of hFⅨ expression vectorswith the retroviral vector frame and examined their hFⅨexpression in skeletal muscle cells. Firstly, we introducedhFⅨ minigene (hFⅨ ml or hFⅨ m2), which contains atruncated first intron (1. 4 kb or 0. 3 kb) of hFⅨ展开更多
In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the P...In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the PS density,a time-series InSAR chain termed as"super-resolution persistent scatterer interferometry"(SR-PSI)is proposed.In this study,we investigate certain important properties of SR-PSI.First,we review the main workflow and dataflow of SR-PSI.It is shown that in the implementation of the Capon algorithm,the diagonal loading(DL)approach should be only used when the condition number of the covariance matrix is sufficiently high to reduce the discontinuities between the joint images.We then discuss the density and positioning accuracy of PS when compared with traditional PSI.The theory and experimental results indicate that SR-PSI can increase the PS density in urban areas.However,it is ineffective for the rural areas,which should be an important consideration for the engineering application of SR-PSI.Furthermore,we validate that the positioning accuracy of PS can be improved by SRPSI via simulations.展开更多
汉语中常用“横竖”、“贵贱”、“死活”、“高低”、“好歹”等词语来加强语气,表达“无论如何……”,“不管怎样……”的含意;英语中也有类似的短语,根据其着眼点的不同,约可分为以下几种。 A.从代价着眼: 1.at all costs(不惜任何...汉语中常用“横竖”、“贵贱”、“死活”、“高低”、“好歹”等词语来加强语气,表达“无论如何……”,“不管怎样……”的含意;英语中也有类似的短语,根据其着眼点的不同,约可分为以下几种。 A.从代价着眼: 1.at all costs(不惜任何牺牲或代价)展开更多
The following is the third part of 'Create a New Situation in All Fields of Socialist Modernization'—Report to the 12th National Congress of The Communist Party of China, September 1, 1982, by Hu Yaobang.
文摘Tibet Plateau has uplifted greatly in the Late Cenozoic era (Li Jijun et al., 1979; Sun Honglie, 1996; Shi Yafeng et al., 1998). The uplift will unquestionably influence the environment and climate of the plateau in the same time (such as resulting in the decrease of temperature) and leave some footprint on the contemporary sediments on or around the plateau. So, there must be some persistence component in the environmental and climatic evolution reflected by the geochemical information in the contemporary sediments. TS95, namely Tianshuihai Lake core is at the south frank of West Kunlun Mountain of Tibet Plateau and is suitable for the investigation of the persistence component. Using R/S analysis, Zhou Houyun et al. (1999) have previously calculated the Hurst index H of the three ferric indexes, FeO, Fe\-2O\-3 and ratio of FeO/ Fe\-2O\-3, from TS95. It is found that all these indexes satisfy Hurst law and they all are greater than 0 5, which means that there are some long run dependencies\|persistence component in the climatic and environmental evolution around Tianshuihai Lake area. This is in accordance with previous work by Yu Suhua et al. (1996). In this paper, the authors use the same method to do some R/S analysis on the other two climatic proxies of TS95, δ 13 C and δ 18 O, which are more suitable than the three ferric indexes to be climatic and environmental proxies. It is found that both the δ 13 C and δ 18 O satisfy Hurst law very well with H δ 13 C =0 875 and H δ 18 O =894, which suggests stronger persistence than the three ferric indexes.
文摘The paper researched effect of adjuvants on activity and persistence of soil-applied herbicide Anwei.There were five adjuvants (fertility, Q7, oil, anionic and nonionic surfactants) in the experiment. We explored the influence of adjuvants on activity and persistence of Anwei by field trial. The results indicated that Q7, oil, anionic surfactant can increased activity of Anwei, and can lengthened its persistence for about five days.
基金Supported by National Natural Science Foundation of China(61911530398,12231012)Consultancy Project by the Chinese Academy of Engineering(2022-JB-06,2023-JB-12)+3 种基金the Natural Science Foundation of Fujian Province of China(2021J01621)Special Projects of the Central Government Guiding Local Science and Technology Development(2021L3018)Royal Society of Edinburgh(RSE1832)Engineering and Physical Sciences Research Council(EP/W522521/1).
文摘A stochastic epidemic model with two age groups is established in this study,in which the susceptible(S),the exposed(E),the infected(I),the hospitalized(H)and the recovered(R)are involved within the total population,the aging rates between two age groups are set to be constant.The existence-and-uniqueness of global positive solution is firstly showed.Then,by constructing several appropriate Lyapunov functions and using the high-dimensional Itô’s formula,the sufficient conditions for the stochastic extinction and stochastic persistence of the exposed individuals and the infected individuals are obtained.The stochastic extinction indicator and the stochastic persistence indicator are less-valued expressions compared with the basic reproduction number.Meanwhile,the main results of this study are modified into multi-age groups.Furthermore,by using the surveillance data for Fujian Provincial Center for Disease Control and Prevention,Fuzhou COVID-19 epidemic is chosen to carry out the numerical simulations,which show that the age group of the population plays the vital role when studying infectious diseases.
基金National Key R&D Program of China(2023YFB3506600)。
文摘Y_(3)Al_(2)Ga_(3)O_(12):Ce^(3+),Cr^(3+)(YAGG:Ce^(3+),Cr^(3+)),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent luminescent material applications.At present,YAGG:Ce^(3+),Cr^(3+)powders exhibit good persistent performance,but their persistent performance of ceramics still needs to be further improved to meet the new requirements.In this work,(Y_(0.998)Ce_(0.002))_(3)(Al_(1-x)Cr_(x))_(2)Ga_(3)O_(12) ceramics with different Cr^(3+)doping concentrations were prepared by solid-state reaction,including air pre-sintering,hot isostatic pressing(HIP)post-treatment and air annealing,to investigate the effects of Cr^(3+)doping concentration on the microstructure,optical properties and persistent performance of the ceramics.The results showed that as the doping concentration of Cr^(3+)increased from 0.025%to 0.2%(in atom),no significant effect of Cr^(3+)concentration on the morphology of pre-sintered ceramics or HIP post-treatment ceramics was observed,but the in-line transmittance gradually increased while the persistent performance gradually decreased.Among them,YAGG:Ce^(3+),Cr^(3+)ceramics doped with 0.025%Cr^(3+)showed the strongest initial luminescence intensity exceeding 6055 mcd/m^(2) and a persistent time of 1030 min after air pre-sintering combined with HIP post-treatment and air annealing.By optimizing the Cr^(3+)doping concentration and the fabrication process,the persistent luminescence(PersL)performance of the YAGG:Ce^(3+),Cr^(3+)ceramics was obviously improved.
基金Project(11102224)supported by the National Natural Science Foundation of ChinaProject(2009QL05)supported by the Fundamental Research Funds for the Central Universities of China
文摘Anisotropic strength and deformability of the rock mass with non-persistent joints are governed by cracking process of the rock bridges. The dependence of cracking process of jointed rock masses on the two important geometrical parameters, joint orientation and joint persistence, was studied systematically by carrying out a series of uniaxial compression tests on gypsum specimens with regularly arranged multiple parallel pre-existing joints. According to crack position, mechanism and temporal sequence, seven types of crack initiations and sixteen types of crack coalescences, were identified. It was observed that both tensile cracks and shear cracks can emanate from the pre-existing joints as well as the matrix. Vertical joints were included and coplanar tensile cracks initiation and coalescence were observed accordingly. For specimen with joint inclination angle ,8=75~, it was found that collinear joints can be linked not only by coplanar shear cracks but also by mixed tensile-shear cracks, and that a pair of them can form a small rotation block. Seven failure modes, including axial cleavage, crushing, crushing and rotation of new blocks, stepped failure, stepped failure and rotation of new blocks, shear failure along a single plane and shear failure along multiple planes, were observed. These modes shift gradually in accordance with the combined variation of joint orientation and joint persistence. It is concluded that cracking process and failure modes are more strongly affected by joint orientation than by joint persistence, especially when joint inclination angle is larger than 45~. Finally, variations of macroscopic mechanical behaviors with the two geometrical parameters, such as patterns of the complete axial stress-axial strain curves, peak strength and elastic modulus, are summarized and their mechanisms are successfully explained according to their different cracking process.
文摘In the present paper,the nonautonomous two-species Predator-Prey models with diffusion are considered. Prey species can diffuse between two patches, while the predator species is confined to one patch and cannot diffuse. It is proved that if the coefficients satisfy certain inequalities,then the system can be made persistent and have a strictly positive periodic orbit which is glotally asymptotically stable.
基金the National Natural Science Foundation of China (60574011)Department of Science and Technology of Liaoning Province (2001401041).
文摘The singularly perturbed bifurcation subsystem is described, and the test conditions of subsystem persistence are deduced. By use of fast and slow reduced subsystem model, the result does not require performing nonlinear transformation. Moreover, it is shown and proved that the persistence of the periodic orbits for Hopf bifurcation in the reduced model through center manifold. Van der Pol oscillator circuit is given to illustrate the persistence of bifurcation subsystems with the full dynamic system.
基金Projects(41204012, 41274026, 41274024, 40825012, 41021003, 41174016) supported by the National Natural Science Foundation of China
文摘The long-term reclamation-induced ground subsidence in Macao, a coastal city of southern China was investigated. Persistent scatterer interferometry (PSI) technique was applied to retrieve the deformation rate in Macao during the period from April 2003 to August 2010 with a total of 41 scenes of descending ASAR data sets. The PSI-retrieved results show a relatively stable pattern in Macao Peninsula, Taipa Island and Coloane Island, with an average subsidence velocity of -3 mm/a. In contrast, relatively large subsidence rates are highlighted in Cotai area, a new reclamation land in 1990s, in which an average subsidence velocity is about -10 mm/a. A consistent relationship between the PSI results and the leveling measurements indicate that this PSI technique is an effective tool to monitor the reclamation-induced ground subsidence with a high accuracy and adequate spatial details. Accordingly, the valuable ground subsidence results generated by PSI can be used not only for early detection and remedial activities of potential settlement of building, but also for helping the local government to formulate regional sustainable development planning and decision-making in disaster prevention and mitigation.
基金This project was supported by the National Natural Science Foundation of China (60074001) and the Natural ScienceFoundation of Shandong Province (Y2000G02)
文摘The optimal control problem for linear time-varying systems affected by external persistent disturbances with known dynamic characteristics but unknown initial conditions is consider and a design procedure of a feedforward and feedbaek optimal controller is presented. The condition of existence and uniqueness of the control law is given. The disturbanee observer is proposed to make the feedforward control law realizable physically. Simulation results demonstrate that the feedforward and feedbaek optimal control law is more effective and robust than the elassical state feedbaek control law with respect to external disturbanees.
基金supported by the National Natural Science Foundation of China(60574023)the Natural Science Foundation of Shandong Province(Z2005G01).
文摘An optimal tracking control （OTC） problem for linear time-delay large-scale systems affected by external persistent disturbances is investigated. Based on the internal model principle, a disturbance compensator is constructed. The system with persistent disturbances is transformed into an augmented system without persistent disturbances. The original OTC problem of linear time-delay system is transformed into a sequence of linear two- point boundary value （TPBV） problems by introducing a sensitivity parameter and expanding Maclaurin series around it. By solving an OTC law of the augmented system, the OTC law of the original system is obtained. A numerical simulation is provided to illustrate the effectiveness of the proposed method.
文摘Myoblast-mediated gene transfer approach has agreat potential to be developed into a durable genetherapy method for various diseases. To increase theexpression level of human factor Ⅸ (hFⅨ) in musclecells, we constructed a series of hFⅨ expression vectorswith the retroviral vector frame and examined their hFⅨexpression in skeletal muscle cells. Firstly, we introducedhFⅨ minigene (hFⅨ ml or hFⅨ m2), which contains atruncated first intron (1. 4 kb or 0. 3 kb) of hFⅨ
基金supported by the National Natural Science Foundation of China(62101284)the State Key Laboratory of Geo-Information Engineering and Key Laboratory of Surveying and Mapping Science and Geospatial Information Technology of Ministry of Natural Resources+4 种基金China Academy of Surveying and Mapping(2021-03-11)the Natural Science Project of Jiangsu Province(21KJB420003)Nanjing University of Posts and Telecommunications Start-up Fund(NY221033,NY220168)the Foundation of Jiangsu Province Shuangchuang Doctor Grant(JSSCBS20210543)Beijing Key Laboratory of Urban Spatial Information Engineering(20210215)。
文摘In the application of persistent scatterer interferometry(PSI),deformation information is extracted from persistent scatterer(PS)points.Thus,the density and position of PS points are critical for PSI.To increase the PS density,a time-series InSAR chain termed as"super-resolution persistent scatterer interferometry"(SR-PSI)is proposed.In this study,we investigate certain important properties of SR-PSI.First,we review the main workflow and dataflow of SR-PSI.It is shown that in the implementation of the Capon algorithm,the diagonal loading(DL)approach should be only used when the condition number of the covariance matrix is sufficiently high to reduce the discontinuities between the joint images.We then discuss the density and positioning accuracy of PS when compared with traditional PSI.The theory and experimental results indicate that SR-PSI can increase the PS density in urban areas.However,it is ineffective for the rural areas,which should be an important consideration for the engineering application of SR-PSI.Furthermore,we validate that the positioning accuracy of PS can be improved by SRPSI via simulations.
文摘The following is the third part of 'Create a New Situation in All Fields of Socialist Modernization'—Report to the 12th National Congress of The Communist Party of China, September 1, 1982, by Hu Yaobang.
