The virial theorem is written by using the canonical equations of motion in classical mechanics. A moving particle with an initial speed in an n-particle system is considered. The distance of the moving particle from ...The virial theorem is written by using the canonical equations of motion in classical mechanics. A moving particle with an initial speed in an n-particle system is considered. The distance of the moving particle from the origin of the system to the final position is derived as a function of the kinetic energy of the particle. It is thought that the considered particle would not collide with other particles in the system. The relation between the final and initial distance of the particle from the origin of the system is given by a single equation.展开更多
In this paper,we study the Bowen entropy of stable sets in positive entropy G-system of amenable group actions.The lower bound of the Bowen entropy of these sets are estimated.
Controlled-release/stable nitrogen(N)fertilizers can improve vegetable yields and achieve lower greenhouse gas emissions,resulting in cost-effective and environmentally friendly vegetable production.However,there has ...Controlled-release/stable nitrogen(N)fertilizers can improve vegetable yields and achieve lower greenhouse gas emissions,resulting in cost-effective and environmentally friendly vegetable production.However,there has been limited research on the controlled-release/stable N fertilization in long-term fixed-position vegetable rotation fields.In this study,a five-year field experiment was conducted to examine the effects of long-term controlled-release/stable N fertilization in reducing greenhouse gas emissions and increasing lettuce yield.Six distinct treatments were employed for N fertilization:the control without N fertilizer(CK),normal local farming practices with application of urea fertilizer at 400 kg N ha^(-1)(T1),optimized application of urea at 320 kg N ha^(-1)(T2),optimized application of urea at 320 kg N ha^(-1)with supplementation of 1.0 kg ha^(-1)3,4-dimethylpyrazole phosphate(DMPP)as N inhibitor(T3),application of polyurethane-coated urea at 320 kg N ha^(-1)(T4),and application of polyurethane-coated urea at 320 kg N ha^(-1)with supplementation of 1.0 kg ha^(-1)DMPP(T5).The results showed that the T3,T4,and T5 treatments using controlled-release/stable N fertilization emitted about 12.2%-56.7%less average annual cumulative nitrous oxide(N_(2)O)and 1.31%-10.0%less carbon dioxide(CO_(2))than the T2 treatment.Nitrous oxide and CO_(2)emissions from the T4 and T5 treatments were considerably lower than those from the T3 treatment.No significant seasonal or interannual variability was observed in N_(2)O and CO_(2)emissions.The observed phenomena were attributed to the fluctuations in soil ammonium-and nitrate-N contents.The findings in this study revealed that long-term controlled-release/stable N fertilization resulted in reduced field N loss,benefitting vegetable yields without increasing CO_(2)emissions and highlighting the application potential of this technique for sustainable agricultural production.展开更多
Interactions among ecosystem services(ESs)are spatially heterogeneous,shaped by both stable(unidirectional)and unstable(context-dependent)influences of socio-economic development and climate change.These complexities ...Interactions among ecosystem services(ESs)are spatially heterogeneous,shaped by both stable(unidirectional)and unstable(context-dependent)influences of socio-economic development and climate change.These complexities pose significant challenges for spatially adaptive ecosystem management.Ecosystem service bundles(ESBs),as recurring combinations of ESs,offer a valuable framework to capture such interactions.Here,we proposed an integrated analytical framework that combines K-means clustering,the geographical detector(GD)model,and geographically and temporally weighted regression(GTWR)models to evaluate how socio-economic and climatic drivers influence ESBs across space and time.Using Hanshui River Basin(HRB)in central China as a case study,we quantified ES dynamics from 2000 to 2020,identified ESBs and stable and unstable effects of multiple drivers.The results showed that carbon sequestration(CS),water yield(WY),and aesthetic landscape(AL)increased by 32.80%,9.00%,and 7.34%,respectively,while soil retention(SR)and food supply(FS)declined by 8.38%and 5.36%.Five distinct ESBs were identified,namely ecologically fragile bundle(EFB),agricultural production bundle(APB),water supply bundle(WSB),forest ecological bundle(FEB),and ecological conservation bundle(ECB).Among these,FEB expanded to more than 35.75%of the HRB,and APB exhibited the sharpest decline(-28.64%).Land use intensity(LUI)was the primary driver of the spatial heterogeneity of ESBs,while synergistic and nonlinear interactions among multiple factors increasingly amplified their effects over time.Notably,annual precipitation(AP)emerged as the only stable basin-scale driver,consistently enhancing ES performance,while gross domestic product(GDP)and normalized difference vegetation index(NDVI)had stable yet spatially differentiated effects across bundles.Our findings highlight the significance of distinguishing stable/unstable driver effects on ES dynamics to inform regionally adaptive ecosystem governance.The proposed framework provides valuable insights into ES interactions,identify spatial priorities,and support policy interventions that balance ecological conservation with socio-economic development.展开更多
Aim To study singular points, closed orbits, stable manifolds and unstable manifolds of a second order autonomous Birkhoff system. Methods Qualitative methods of ordinary differential equation were used. Results and ...Aim To study singular points, closed orbits, stable manifolds and unstable manifolds of a second order autonomous Birkhoff system. Methods Qualitative methods of ordinary differential equation were used. Results and Conclusion The criteria for singular points, closed orbits and hyperbolic equilibrium points of a second order autonomous Birkhoff system are given. Moreover the stability of equilibria, stable manifolds and unstable manifolds are obtained.展开更多
Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution chara...Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13 C natural abundance technique, ecologists are able to understand the photosynthetic path and CO 2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13 C labeled technique, the effects of elevated CO 2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15 N natural abundance technique, ecologists are able to analyze the biological N 2 -fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15 N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope ( 34 S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future.展开更多
On the basis of hydrochemical observation and experimental calculation, the features of stable carbon isotope geochemistry in the karst dynamic systems of the Guilin Karst Experimental Site, Huanglong Ravine and Wujia...On the basis of hydrochemical observation and experimental calculation, the features of stable carbon isotope geochemistry in the karst dynamic systems of the Guilin Karst Experimental Site, Huanglong Ravine and Wujiangdu Dam Site are summarized in this study. Furthermore, an attempt has been made to solve several geochemical problems, such as the origin of CO2 in the system, kinetic fractionation of carbon isotopes during calcite deposition, hydrochemistry and formation of tufa, and carbon-14 dating of tufa of hydrothermal origin. The results show that three kinds of karst dynamic system can be distinguished: (1) the shallow system, such as the Guilin Karst Experimental Site, in which soil CO2 provides the an active agent for karst processes; (2) the geothermal system, such as the Huanglong Ravine, in which metamorphic or/ and juvenile CO, is the source of activity for karst; (3) the anthropogenic system, such as the Wujiangdu Dam Site, in which the stable carbon isotope geochemical and hydrochemical features have been greatly affected by human activity.展开更多
Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also in...Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also included white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila. The mean δ^(13)C value for all the biomass groups in polyculture ecosystem ranged from -25.61‰ to -16.60‰, and the mean δ^(15)N value ranged from 6.80‰ to 13.09‰. Significant difference in the δ^(13)C value was found between particulate organic matter(POM) and sediment organic matter(SOM)(P < 0.05), indicating that these two organic matter pools have different material sources. Assuming that a ^(13)C-enrichment factor of 1.00‰ and a ^(15)N-enrichment factor of 2.70‰ existed between consumer and prey, diets of the four cultured animals were estimated using a stable isotope mixing model. The estimated model results indicated that P. trituberculatus mainly feed on Aloidis laevis; L. vannamei mainly feed on shrimp feed; while A. laevis, R. philippinarum and L. haematochelia mainly feed on POM. Shrimp feed was also an important food source of R. philippinarum and L. haematochelia. The diets of P. trituberculatus, L. vannamei, R. philippinarum, and L. haematochila showed complementary effects in this polyculture ecosystem. Our finding indicated that the polyculture of these four organisms with suitable farming density could make an effective use of most of the food sources, which can make a highly efficient polyculture ecosystem.展开更多
This paper reports a new simple four-dimensional（4 D） hyperjerk chaotic system. The proposed system has only one stable equilibrium point. Hence, its strange attractor belongs to the category of hidden attractors. T...This paper reports a new simple four-dimensional（4 D） hyperjerk chaotic system. The proposed system has only one stable equilibrium point. Hence, its strange attractor belongs to the category of hidden attractors. The proposed system exhibits various dynamical behaviors including chaotic, periodic, stable nature, and coexistence of various attractors. Numerous theoretical and numerical methods are used for the analyses of this system. The chaotic behavior of the new system is validated using circuit implementation. Further, the synchronization of the proposed systems is shown by designing an adaptive integrator backstepping controller. Numerical simulation validates the synchronization strategy.展开更多
To understand its source,distribution,storage,and translocation in the subtropical forest ecosystems,mercury(Hg)concentrations and stable isotopes in forest biomass tissues(foliage,branch,bark,and trunk)were investiga...To understand its source,distribution,storage,and translocation in the subtropical forest ecosystems,mercury(Hg)concentrations and stable isotopes in forest biomass tissues(foliage,branch,bark,and trunk)were investigated at Ailao Mountain National Nature Reserve,Southwest China.The total Hg(THg)concentrations in the samples show the following trend:mature foliage(57±19 ng g-1)>bark(11±4.0 ng g-1)>branch(5.4±2.5 ng g-1)>trunk(1.6±0.7 ng g-1).Using the measured THg concentrations and the quantity of respective biomasses,the Hg pools in the forest are:wood(60±26μg m-2)>bark(51±18μg m-2)>foliage(41±11μg m-2)>branch(26±8.3μg m-2).The tree biomasses displayed negativeδ202Hg(-1.83‰to-3.84‰)andΔ199Hg(-0.18‰to-0.62‰).The observedΔ200Hg(-0.08‰to 0.04‰)is not significantly from zero.AΔ199Hg/Δ201Hg ratio of 1.05 was found in tree biomasses,suggesting that mercury has undergone Hg(Ⅱ)photoreduction processes.A Hg-isotope based binary mixing model suggests that Hg in the tree biomasses mainly originated from foliage uptake of atmospheric Hg0,constituting 67%,80%,and 77%of Hg in wood,branch,and bark,respectively.Our study sheds new light on the transportation and sources of Hg in the subtropical forest ecosystems.展开更多
In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ 13C) and some main physical, chemical parameters (soil ...In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ 13C) and some main physical, chemical parameters (soil moisture, pH, soil density, content of humic, fulvic, total N, total P, total K) in alluvial soil of Dan Phuong region—Vietnam at a depth of 0 - 30 cm when we changed the regime from 2 maize -1 rice crop to 2 rice - 1 maize crop per 1 year. In addition to analyzing the main parameters in soil, C content and its δ 13C value in parts of rice and maize (root, stem and leaf) were also analyzed to assess the contribution of plant residues on soil organic carbon content after harvest. The experiment was carried out in 2016-2017 on the field with the traditional farming method of local farmers along with the tropical monsoon weather conditions of the North-Vietnam. The results showed that SOC had positive correlation with total N, total P parameters and negative correlation with δ 13C values of soil samples at two layers (0 - 15 cm and 15 - 30 cm). The average of total dry biomass (stem, stump + roots and leaf parts) per 1 rice and 1 maize crop was 10.64 Mg/ha and 9.09 Mg/ha, respectively. The average of δ 13C value of rice (C3 plant) was -29.78‰ and its value of maize (C4 plant) was -12.61‰. The new plant (rice) contributes to the total soil organic carbon content from 11.31% to 44.14% at the 0 - 15 cm layer and from 6.55% to 11.31% at the 15 - 30 cm layer in one-year experiment period.展开更多
Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised Z...Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised ZnO. ZnO is thermodynamically stable up to 300GPa and zinc peroxide （Zn02, space group Pa3） is metastable under lower pressure. Insulating I4/mcm-Zn02 is thermodynamically stable between 128.3-300 GPa. Insulated metastable P3121-Zn02, controlling the pressure range of 51.5-128.3 GPa, has a wide band gap compared to the Pa3-Zn02 and I4/mem-Zn02. Phonon and elastic constant calculations conclude the dynamical and mechanical stability for the explored thermodynamically stable or metastable structures.展开更多
This study explores a stable model order reduction method for fractional-order systems. Using the unsymmetric Lanczos algorithm, the reduced order system with a certain number of matched moments is generated. To obtai...This study explores a stable model order reduction method for fractional-order systems. Using the unsymmetric Lanczos algorithm, the reduced order system with a certain number of matched moments is generated. To obtain a stable reduced order system, the stable model order reduction procedure is discussed. By the revised operation on the tridiagonal matrix produced by the unsymmetric Lanczos algorithm, we propose a reduced order modeling method for a fractional-order system to achieve a satisfactory fitting effect with the original system by the matched moments in the frequency domain. Besides, the bound function of the order reduction error is offered. Two numerical examples are presented to illustrate the effectiveness of the proposed method.展开更多
We investigate the effect of alpha stable noise on stochastic resonance in a single-threshold sensor system by analytic deduction and stochastic simulation. It is shown that stochastic resonance occurs in the threshol...We investigate the effect of alpha stable noise on stochastic resonance in a single-threshold sensor system by analytic deduction and stochastic simulation. It is shown that stochastic resonance occurs in the threshold system in alpha stable noise environment, but the resonant effect becomes weakened as the alpha stable index decreases or the skewness parameter of alpha stable distribution increases. In particular, for Cauchy noise a nonlinear relation among the optimal noise deviation parameter, the signal amplitude and the threshold is analytically obtained and illustrated by using the extreme value condition for the output signal-to-noise ratio. The results presented in this communication should have application in signal detection and image restoration in the non-Gaussian noisy environment.展开更多
The concept of labor division and multi-module cooperation of microbial consortia offers it promising potentials in various areas,such as the utilization of complex substrates,synthesis of natural compounds with long ...The concept of labor division and multi-module cooperation of microbial consortia offers it promising potentials in various areas,such as the utilization of complex substrates,synthesis of natural compounds with long metabolic pathways and remediation of environmental pollutants within a hostile environment.Consequently,synthetic microbial consortia represent a new frontier for synthetic biology because they can solve more complex problems than monocultures.However,current research on microbial consortia often involves the simple mixing of multiphase systems,where strains are co-cultured sequentially or individually cultured and then mixed-cultured.The instability and low efficiency of microbial consortia systems hindered their practical application.To construct a stable and efficient microbial consortium,it is essential to consider the different growth and metabolic characteristics of strains,the competition for various nutrients as well as the complex carbon,energy and signaling dynamics within the system.In this review,we provide a progressive strategy for constructing a stable and efficient microbial consortium system across three stages:compromised stage(work together),microenvironment-oriented stage(work better),and metabolite delivery-enhanced stage(work best).The detailed methods and points for attention of each stage are summarized,with a highlight on the technical bottleneck and application limitations.Through the integration of interdisciplinary strategies,such as materials science and mathematical models,the goal of building a stable and efficient microbial consortium is constantly advanced.展开更多
The stability degree of periodic solution of nonlinear nonautonomous system was defined by means of the Floquet theory. A method evaluating the stability degree of periodic solution based on transient response was pre...The stability degree of periodic solution of nonlinear nonautonomous system was defined by means of the Floquet theory. A method evaluating the stability degree of periodic solution based on transient response was presented by the aid of the concept of dynamic,systems or flows. The critical value of a system was determined by the condition, i.e., its stability degree equals zero. Stable regions of rotor systems with balanced and unbalanced disk supported on lubricated bearings were calculated. The study shows that stable region decreases with the increase of speed for a balanced rotor system and decreases with the increase of unbalance for an unbalanced rotor system. Stable regions of periodic solutions are less than that of equilibrium points under the same systematic conditions.展开更多
This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution o...This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution of system. We obtained the necessary and sufficient conditions for there exists the stable solution.展开更多
The question of stable control system of bank-to-turn (BTT) missiles is a bottleneckin BTT technology. Integrate fuzzy logic stable control system of BTT missiles is designed in whichthree main problems are resolved. ...The question of stable control system of bank-to-turn (BTT) missiles is a bottleneckin BTT technology. Integrate fuzzy logic stable control system of BTT missiles is designed in whichthree main problems are resolved. How to select input variables Of the fuzzy logic controller and howto guarantee completeness of the output control are two of them. The last one is how to coordinatethe fuzzy logic controllers in integrate fuzzy logic stable control system. Simulating results prov that integrate fuzzy logic stable coatrol system of BTT missiles is sueccessful, and it can be widelyused in future.展开更多
Objective:To systematically evaluate the effect and safety of additional Yupingfeng powder combined with western medicine for the stable period of chronic obstructive pulmonary disease(COPD).Method:Databases including...Objective:To systematically evaluate the effect and safety of additional Yupingfeng powder combined with western medicine for the stable period of chronic obstructive pulmonary disease(COPD).Method:Databases including Pubmed、Web of Science、Cochrane Library、CNKI、VIP、CBM and Wanfang Data base,were searched for relevant randomized controlled trials.for Chinese and English literature about randomized controlled trials of additional Yupingfeng in the treatment of COPD on stable stage which were published from the establishment of the database to December 2019.Two researchers independently screened for,selected studies according to the inclusion and exclusion criteria and extracted data.Methodological quality was evaluated using the Cochrane Risk of Bias tool.Meta-analysis was performed using Revman 5.3 software.Results:Ninetine randomized controlled trials including 1511 patients with COPD were meta-analyzed.The total sample size was 1511.The results showed that the treatment grop with additional Yupingfeng powder could improve the clinical efficacy[OR=0.26,95%CI(0.18,0.37)],FEV1 percentage of the estimated value[MD=4.61,95%CI(2.43,6.79)],6MWD[MD=43.90,95%CI(29.48,58.32)]and patient's immunity IgA[MD=0.25,95%CI(0.17,0.34)]and can mitigate cough effectively[MD=-0.34,95%CI(-0.46,-0.23)].Conclusion:Additional Yupingfeng powder combined with routine treatment for COPD has more advantages than conventional treatment alone in improving the clinical efficacy,lung function,immune function and have less adverse events.As most of the included studies in this systematic evaluation had poor quality,the evidence to support conclusion was weak,so it was necessary to conduct more multi-center clinical trials with high quality methods and rigorous design.展开更多
文摘The virial theorem is written by using the canonical equations of motion in classical mechanics. A moving particle with an initial speed in an n-particle system is considered. The distance of the moving particle from the origin of the system to the final position is derived as a function of the kinetic energy of the particle. It is thought that the considered particle would not collide with other particles in the system. The relation between the final and initial distance of the particle from the origin of the system is given by a single equation.
基金Supported by NSFC(No.11861010),also supported by NSFC(No.12171175),also supported by NSFC(No.12261006)NSF of Guangxi Province(No.2018GXNSFFA281008)Project of Guangxi First Class Disciplines of Statistics(No.GJKY-2022-01)。
文摘In this paper,we study the Bowen entropy of stable sets in positive entropy G-system of amenable group actions.The lower bound of the Bowen entropy of these sets are estimated.
基金supported by the Natural Science Foundation of Shandong Province,China(Nos.ZR2022MD118 and ZR2022MD050)the Beijing Academy of Agricultural and Forestry Sciences Science and Technology Innovation Capacity Construction Project,China(No.20230207)+3 种基金the Humanities and Social Science Foundation Project of Ministry of Education,China(No.22YJCZH166)the Technical System of Ecological Agriculture of Modern Agricultural Technology System in Shandong Province,China(No.SDAIT-30-02)the National Key Research and Development Program of China(No.2023YFD1701901)the Fundamental Research Funds for Central Non-profit Scientific Institution of China(No.1610132023006).
文摘Controlled-release/stable nitrogen(N)fertilizers can improve vegetable yields and achieve lower greenhouse gas emissions,resulting in cost-effective and environmentally friendly vegetable production.However,there has been limited research on the controlled-release/stable N fertilization in long-term fixed-position vegetable rotation fields.In this study,a five-year field experiment was conducted to examine the effects of long-term controlled-release/stable N fertilization in reducing greenhouse gas emissions and increasing lettuce yield.Six distinct treatments were employed for N fertilization:the control without N fertilizer(CK),normal local farming practices with application of urea fertilizer at 400 kg N ha^(-1)(T1),optimized application of urea at 320 kg N ha^(-1)(T2),optimized application of urea at 320 kg N ha^(-1)with supplementation of 1.0 kg ha^(-1)3,4-dimethylpyrazole phosphate(DMPP)as N inhibitor(T3),application of polyurethane-coated urea at 320 kg N ha^(-1)(T4),and application of polyurethane-coated urea at 320 kg N ha^(-1)with supplementation of 1.0 kg ha^(-1)DMPP(T5).The results showed that the T3,T4,and T5 treatments using controlled-release/stable N fertilization emitted about 12.2%-56.7%less average annual cumulative nitrous oxide(N_(2)O)and 1.31%-10.0%less carbon dioxide(CO_(2))than the T2 treatment.Nitrous oxide and CO_(2)emissions from the T4 and T5 treatments were considerably lower than those from the T3 treatment.No significant seasonal or interannual variability was observed in N_(2)O and CO_(2)emissions.The observed phenomena were attributed to the fluctuations in soil ammonium-and nitrate-N contents.The findings in this study revealed that long-term controlled-release/stable N fertilization resulted in reduced field N loss,benefitting vegetable yields without increasing CO_(2)emissions and highlighting the application potential of this technique for sustainable agricultural production.
基金Under the auspices of National Natural Science Foundation of China(No.42171414)。
文摘Interactions among ecosystem services(ESs)are spatially heterogeneous,shaped by both stable(unidirectional)and unstable(context-dependent)influences of socio-economic development and climate change.These complexities pose significant challenges for spatially adaptive ecosystem management.Ecosystem service bundles(ESBs),as recurring combinations of ESs,offer a valuable framework to capture such interactions.Here,we proposed an integrated analytical framework that combines K-means clustering,the geographical detector(GD)model,and geographically and temporally weighted regression(GTWR)models to evaluate how socio-economic and climatic drivers influence ESBs across space and time.Using Hanshui River Basin(HRB)in central China as a case study,we quantified ES dynamics from 2000 to 2020,identified ESBs and stable and unstable effects of multiple drivers.The results showed that carbon sequestration(CS),water yield(WY),and aesthetic landscape(AL)increased by 32.80%,9.00%,and 7.34%,respectively,while soil retention(SR)and food supply(FS)declined by 8.38%and 5.36%.Five distinct ESBs were identified,namely ecologically fragile bundle(EFB),agricultural production bundle(APB),water supply bundle(WSB),forest ecological bundle(FEB),and ecological conservation bundle(ECB).Among these,FEB expanded to more than 35.75%of the HRB,and APB exhibited the sharpest decline(-28.64%).Land use intensity(LUI)was the primary driver of the spatial heterogeneity of ESBs,while synergistic and nonlinear interactions among multiple factors increasingly amplified their effects over time.Notably,annual precipitation(AP)emerged as the only stable basin-scale driver,consistently enhancing ES performance,while gross domestic product(GDP)and normalized difference vegetation index(NDVI)had stable yet spatially differentiated effects across bundles.Our findings highlight the significance of distinguishing stable/unstable driver effects on ES dynamics to inform regionally adaptive ecosystem governance.The proposed framework provides valuable insights into ES interactions,identify spatial priorities,and support policy interventions that balance ecological conservation with socio-economic development.
文摘Aim To study singular points, closed orbits, stable manifolds and unstable manifolds of a second order autonomous Birkhoff system. Methods Qualitative methods of ordinary differential equation were used. Results and Conclusion The criteria for singular points, closed orbits and hyperbolic equilibrium points of a second order autonomous Birkhoff system are given. Moreover the stability of equilibria, stable manifolds and unstable manifolds are obtained.
基金Under the auspices of Knowledge Innovation Programs of Chinese Academy of Sciences (No. KZCX2-YW-223)National Natural Science Foundation of China (No. 40803023)+1 种基金Key Program of Natural Science Foundation of Shandong Province(No. ZR2010DZ001)Talents Foundation of Chinese Academy of Sciences (No. AJ0809BX-036)
文摘Stable isotope techniques have been proved useful as tools for studying the carbon (C) and nitrogen (N) biogeochemical cycles of ecosystem. This paper firstly introduced the basic principles and the distribution characteristics of stable isotope, then reviewed the recent advances and applications of stable isotope in the C and N biogeochemical cycles of ecosystem. By applying the 13 C natural abundance technique, ecologists are able to understand the photosynthetic path and CO 2 fixation of plants, the CO 2 exchange and C balance status of ecosystem, the composition, distribution and turnover of soil organic C and the sources of organic matter in food webs, while by using the 13 C labeled technique, the effects of elevated CO 2 on the C processes of ecosystem and the sources and fate of organic matter in ecosystem can be revealed in detail. Differently, by applying the 15 N natural abundance technique, ecologists are able to analyze the biological N 2 -fixation, the N sources of ecosystem, the N transformation processes of ecosystem and the N trophic status in food webs, while by using the 15 N labeled technique, the sources, transformation and fate of N in ecosystem and the effects of N input on the ecosystem can be investigated in depth. The applications of both C and N isotope natural abundance and labeled techniques, combined with the elemental, other isotope ( 34 S) and molecular biomarker information, will be more propitious to the investigation of C and N cycle mechanisms. Finally, this paper concluded the problems existed in current researches, and put forward the perspective of stable isotope techniques in the studies on C and N biogeochemical cycles of ecosystem in the future.
基金This research was supproted by IGCP Project 379, National Natural Science Foundation of China (No. 49632100) and the Ministry of Geology and Mineral Resources of China (No. 9501104, Karst Dynamics Laboratory)
文摘On the basis of hydrochemical observation and experimental calculation, the features of stable carbon isotope geochemistry in the karst dynamic systems of the Guilin Karst Experimental Site, Huanglong Ravine and Wujiangdu Dam Site are summarized in this study. Furthermore, an attempt has been made to solve several geochemical problems, such as the origin of CO2 in the system, kinetic fractionation of carbon isotopes during calcite deposition, hydrochemistry and formation of tufa, and carbon-14 dating of tufa of hydrothermal origin. The results show that three kinds of karst dynamic system can be distinguished: (1) the shallow system, such as the Guilin Karst Experimental Site, in which soil CO2 provides the an active agent for karst processes; (2) the geothermal system, such as the Huanglong Ravine, in which metamorphic or/ and juvenile CO, is the source of activity for karst; (3) the anthropogenic system, such as the Wujiangdu Dam Site, in which the stable carbon isotope geochemical and hydrochemical features have been greatly affected by human activity.
基金supported by the National Great Project of Scientific and Technical Supporting Programs(No.2011BAD13B03)the Programs for Excellent Youth Foundation of Shandong Province(No.JQ201009)
文摘Trophic interaction among various biomass groups in a swimming crab Portunus trituberculatus polyculture pond was investigated using carbon and nitrogen stable isotope analysis. The polycultured animal species also included white shrimp Litopenaeus vannamei, short-necked clam Ruditapes philippinarum, and redlip mullet Liza haematochila. The mean δ^(13)C value for all the biomass groups in polyculture ecosystem ranged from -25.61‰ to -16.60‰, and the mean δ^(15)N value ranged from 6.80‰ to 13.09‰. Significant difference in the δ^(13)C value was found between particulate organic matter(POM) and sediment organic matter(SOM)(P < 0.05), indicating that these two organic matter pools have different material sources. Assuming that a ^(13)C-enrichment factor of 1.00‰ and a ^(15)N-enrichment factor of 2.70‰ existed between consumer and prey, diets of the four cultured animals were estimated using a stable isotope mixing model. The estimated model results indicated that P. trituberculatus mainly feed on Aloidis laevis; L. vannamei mainly feed on shrimp feed; while A. laevis, R. philippinarum and L. haematochelia mainly feed on POM. Shrimp feed was also an important food source of R. philippinarum and L. haematochelia. The diets of P. trituberculatus, L. vannamei, R. philippinarum, and L. haematochila showed complementary effects in this polyculture ecosystem. Our finding indicated that the polyculture of these four organisms with suitable farming density could make an effective use of most of the food sources, which can make a highly efficient polyculture ecosystem.
文摘This paper reports a new simple four-dimensional（4 D） hyperjerk chaotic system. The proposed system has only one stable equilibrium point. Hence, its strange attractor belongs to the category of hidden attractors. The proposed system exhibits various dynamical behaviors including chaotic, periodic, stable nature, and coexistence of various attractors. Numerous theoretical and numerical methods are used for the analyses of this system. The chaotic behavior of the new system is validated using circuit implementation. Further, the synchronization of the proposed systems is shown by designing an adaptive integrator backstepping controller. Numerical simulation validates the synchronization strategy.
基金funded by the National Natural Science Foundation of China(No.41430754)。
文摘To understand its source,distribution,storage,and translocation in the subtropical forest ecosystems,mercury(Hg)concentrations and stable isotopes in forest biomass tissues(foliage,branch,bark,and trunk)were investigated at Ailao Mountain National Nature Reserve,Southwest China.The total Hg(THg)concentrations in the samples show the following trend:mature foliage(57±19 ng g-1)>bark(11±4.0 ng g-1)>branch(5.4±2.5 ng g-1)>trunk(1.6±0.7 ng g-1).Using the measured THg concentrations and the quantity of respective biomasses,the Hg pools in the forest are:wood(60±26μg m-2)>bark(51±18μg m-2)>foliage(41±11μg m-2)>branch(26±8.3μg m-2).The tree biomasses displayed negativeδ202Hg(-1.83‰to-3.84‰)andΔ199Hg(-0.18‰to-0.62‰).The observedΔ200Hg(-0.08‰to 0.04‰)is not significantly from zero.AΔ199Hg/Δ201Hg ratio of 1.05 was found in tree biomasses,suggesting that mercury has undergone Hg(Ⅱ)photoreduction processes.A Hg-isotope based binary mixing model suggests that Hg in the tree biomasses mainly originated from foliage uptake of atmospheric Hg0,constituting 67%,80%,and 77%of Hg in wood,branch,and bark,respectively.Our study sheds new light on the transportation and sources of Hg in the subtropical forest ecosystems.
文摘In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ 13C) and some main physical, chemical parameters (soil moisture, pH, soil density, content of humic, fulvic, total N, total P, total K) in alluvial soil of Dan Phuong region—Vietnam at a depth of 0 - 30 cm when we changed the regime from 2 maize -1 rice crop to 2 rice - 1 maize crop per 1 year. In addition to analyzing the main parameters in soil, C content and its δ 13C value in parts of rice and maize (root, stem and leaf) were also analyzed to assess the contribution of plant residues on soil organic carbon content after harvest. The experiment was carried out in 2016-2017 on the field with the traditional farming method of local farmers along with the tropical monsoon weather conditions of the North-Vietnam. The results showed that SOC had positive correlation with total N, total P parameters and negative correlation with δ 13C values of soil samples at two layers (0 - 15 cm and 15 - 30 cm). The average of total dry biomass (stem, stump + roots and leaf parts) per 1 rice and 1 maize crop was 10.64 Mg/ha and 9.09 Mg/ha, respectively. The average of δ 13C value of rice (C3 plant) was -29.78‰ and its value of maize (C4 plant) was -12.61‰. The new plant (rice) contributes to the total soil organic carbon content from 11.31% to 44.14% at the 0 - 15 cm layer and from 6.55% to 11.31% at the 15 - 30 cm layer in one-year experiment period.
基金Supported by the National Natural Science Foundation of China under Grant No 11347007the Qing Lan Project+1 种基金the Colleges and Universities in Jiangsu Province Natural Science Research Project under Grant No 14KJB460013the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised ZnO. ZnO is thermodynamically stable up to 300GPa and zinc peroxide （Zn02, space group Pa3） is metastable under lower pressure. Insulating I4/mcm-Zn02 is thermodynamically stable between 128.3-300 GPa. Insulated metastable P3121-Zn02, controlling the pressure range of 51.5-128.3 GPa, has a wide band gap compared to the Pa3-Zn02 and I4/mem-Zn02. Phonon and elastic constant calculations conclude the dynamical and mechanical stability for the explored thermodynamically stable or metastable structures.
基金supported by the National Natural Science Foundation of China(61304094,61673198,61773187)the Natural Science Foundation of Liaoning Province,China(20180520009)
文摘This study explores a stable model order reduction method for fractional-order systems. Using the unsymmetric Lanczos algorithm, the reduced order system with a certain number of matched moments is generated. To obtain a stable reduced order system, the stable model order reduction procedure is discussed. By the revised operation on the tridiagonal matrix produced by the unsymmetric Lanczos algorithm, we propose a reduced order modeling method for a fractional-order system to achieve a satisfactory fitting effect with the original system by the matched moments in the frequency domain. Besides, the bound function of the order reduction error is offered. Two numerical examples are presented to illustrate the effectiveness of the proposed method.
基金Supported by National Natural Science Foundation of China under Grant Nos.11072182 and 11272241
文摘We investigate the effect of alpha stable noise on stochastic resonance in a single-threshold sensor system by analytic deduction and stochastic simulation. It is shown that stochastic resonance occurs in the threshold system in alpha stable noise environment, but the resonant effect becomes weakened as the alpha stable index decreases or the skewness parameter of alpha stable distribution increases. In particular, for Cauchy noise a nonlinear relation among the optimal noise deviation parameter, the signal amplitude and the threshold is analytically obtained and illustrated by using the extreme value condition for the output signal-to-noise ratio. The results presented in this communication should have application in signal detection and image restoration in the non-Gaussian noisy environment.
基金supported by the National Key Research and Development Program of China(2022YFC2104800)the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(XTD2205)the State Key Laboratory of Materials-Oriented Chemical Engineering(KL-MCE-23A10).
文摘The concept of labor division and multi-module cooperation of microbial consortia offers it promising potentials in various areas,such as the utilization of complex substrates,synthesis of natural compounds with long metabolic pathways and remediation of environmental pollutants within a hostile environment.Consequently,synthetic microbial consortia represent a new frontier for synthetic biology because they can solve more complex problems than monocultures.However,current research on microbial consortia often involves the simple mixing of multiphase systems,where strains are co-cultured sequentially or individually cultured and then mixed-cultured.The instability and low efficiency of microbial consortia systems hindered their practical application.To construct a stable and efficient microbial consortium,it is essential to consider the different growth and metabolic characteristics of strains,the competition for various nutrients as well as the complex carbon,energy and signaling dynamics within the system.In this review,we provide a progressive strategy for constructing a stable and efficient microbial consortium system across three stages:compromised stage(work together),microenvironment-oriented stage(work better),and metabolite delivery-enhanced stage(work best).The detailed methods and points for attention of each stage are summarized,with a highlight on the technical bottleneck and application limitations.Through the integration of interdisciplinary strategies,such as materials science and mathematical models,the goal of building a stable and efficient microbial consortium is constantly advanced.
文摘The stability degree of periodic solution of nonlinear nonautonomous system was defined by means of the Floquet theory. A method evaluating the stability degree of periodic solution based on transient response was presented by the aid of the concept of dynamic,systems or flows. The critical value of a system was determined by the condition, i.e., its stability degree equals zero. Stable regions of rotor systems with balanced and unbalanced disk supported on lubricated bearings were calculated. The study shows that stable region decreases with the increase of speed for a balanced rotor system and decreases with the increase of unbalance for an unbalanced rotor system. Stable regions of periodic solutions are less than that of equilibrium points under the same systematic conditions.
文摘This paper studies the dynamical behavior of a class of total area dependent nonlinear age-structured forest evolution model. We give the problem of equal value for the forest system, and discuss the stable solution of system. We obtained the necessary and sufficient conditions for there exists the stable solution.
文摘The question of stable control system of bank-to-turn (BTT) missiles is a bottleneckin BTT technology. Integrate fuzzy logic stable control system of BTT missiles is designed in whichthree main problems are resolved. How to select input variables Of the fuzzy logic controller and howto guarantee completeness of the output control are two of them. The last one is how to coordinatethe fuzzy logic controllers in integrate fuzzy logic stable control system. Simulating results prov that integrate fuzzy logic stable coatrol system of BTT missiles is sueccessful, and it can be widelyused in future.
基金National Science and Technology Major Projects of Sudden Severe Acute Respiratory Infectious Diseases Treatment New Technology research and the New Scheme(No.2017 zx10204401)。
文摘Objective:To systematically evaluate the effect and safety of additional Yupingfeng powder combined with western medicine for the stable period of chronic obstructive pulmonary disease(COPD).Method:Databases including Pubmed、Web of Science、Cochrane Library、CNKI、VIP、CBM and Wanfang Data base,were searched for relevant randomized controlled trials.for Chinese and English literature about randomized controlled trials of additional Yupingfeng in the treatment of COPD on stable stage which were published from the establishment of the database to December 2019.Two researchers independently screened for,selected studies according to the inclusion and exclusion criteria and extracted data.Methodological quality was evaluated using the Cochrane Risk of Bias tool.Meta-analysis was performed using Revman 5.3 software.Results:Ninetine randomized controlled trials including 1511 patients with COPD were meta-analyzed.The total sample size was 1511.The results showed that the treatment grop with additional Yupingfeng powder could improve the clinical efficacy[OR=0.26,95%CI(0.18,0.37)],FEV1 percentage of the estimated value[MD=4.61,95%CI(2.43,6.79)],6MWD[MD=43.90,95%CI(29.48,58.32)]and patient's immunity IgA[MD=0.25,95%CI(0.17,0.34)]and can mitigate cough effectively[MD=-0.34,95%CI(-0.46,-0.23)].Conclusion:Additional Yupingfeng powder combined with routine treatment for COPD has more advantages than conventional treatment alone in improving the clinical efficacy,lung function,immune function and have less adverse events.As most of the included studies in this systematic evaluation had poor quality,the evidence to support conclusion was weak,so it was necessary to conduct more multi-center clinical trials with high quality methods and rigorous design.
