Rechargeable aqueous zinc-ion batteries(AZIBs)exhibit appreciable potential in the domain of electrochemical energy storage.However,there are serious challenges for AZIBs,for instance zinc dendrite growth,hydrogen evo...Rechargeable aqueous zinc-ion batteries(AZIBs)exhibit appreciable potential in the domain of electrochemical energy storage.However,there are serious challenges for AZIBs,for instance zinc dendrite growth,hydrogen evolution reaction(HER),and corrosion side reactions.Herein,we propose a surface engineering modification strategy for coating the montmorillonite(MMT)layer onto the surface of the Zn anode to tackle these issues,thereby achieving high cycling stability for rechargeable AZIBs.The results reveal that the MMT layer on the surface of the Zn anode is able to provide ordered zincophilic channels for zinc ions migration,facilitating the reaction kinetics of zinc ions.Density functional theory(DFT)calculations and water contact angle(CA)tests prove that MMT@Zn anode exhibits superior adsorption capacity for Zn^(2+)and better hydrophobicity than the bare Zn anode,thereby achieving excellent cycling stability.Moreover,the MMT@Zn||MMT@Zn symmetric cell holds the stable cycling over 5600 h at 0.5 mA cm^(-2)and 0.125 m A h cm^(-2),even exceeding 1800 h long cycling under harsh conditions of 5 m A cm^(-2)and 1.25 m A h cm^(-2).The MMT@Zn||V_(2)O_(5)full cell reaches over 3000 cycles at 2 A g^(-1)with excellent rate capability.Therefore,this surface engineering modification strategy for enhancing the electrochemical performance of AZIBs represents a promising application.展开更多
Existing literature has shown that the control force at the nose could cause dynamic instability for controlled projectiles. To lower the adverse impact on the dual-spin projectile with fixed canards under the premise...Existing literature has shown that the control force at the nose could cause dynamic instability for controlled projectiles. To lower the adverse impact on the dual-spin projectile with fixed canards under the premise of meeting guidance system requirements, the influence of control moment provided by a motor on the flight stability is analyzed in this paper. Firstly, the effect of the rolling movement on stability is analyzed based on the stability criterion derived using the Hurwitz stability theory. Secondly, the evaluation parameters combining the features of different control periods that could assess the variation of stability features after the motor torque are obtained. These effective formulas are used to indicate that, to reduce the flight instability risks, the stabilized rolling speed of roll speed keeping period should be as small as possible; the variation trend of motor torque during the rolling speed controlling period and the roll angle of the forward body during roll angle switching period are recommended corresponding to the projectile and trajectory characteristics. Moreover,detailed numerical simulations of 155 mm dual-spin projectile are satisfactory agreement with the theoretical results.展开更多
Water splitting with proton exchange membrane water electrolyzers(PEMWE)is regarded as a promising pathway for sustainable hydrogen conversion.Additionally,oxygen evolution reaction(OER)is considered as the dominant f...Water splitting with proton exchange membrane water electrolyzers(PEMWE)is regarded as a promising pathway for sustainable hydrogen conversion.Additionally,oxygen evolution reaction(OER)is considered as the dominant factor during the whole process due to the sluggish kinetics.Among the catalysts,Rubased catalysts draw special attention because of their excellent activity and relatively low price.However,the limited stability impedes their further commercialization and tremendous efforts have been devoted to overcome this challenge.This review firstly introduces the basic mechanisms of OER.Then the evaluation protocols and techniques to investigate the stability of Ru-based catalysts are summarized.A detailed elucidation of the possible degradation mechanisms is also critically analyzed.Furthermore,effective strategies to design durable Ru-based catalysts for acidic OER are discussed.Such as heteroatom doping,phase and facet engineering,heterostructure building and support optimization.Finally,promises,perspectives and challenges in developing highly durable Ru-based catalysts for acidic OER are outlined.展开更多
Organic–inorganic hybrid perovskite materials have been focusing more attention in the field of self-powered photodetectors due to their superb photoelectric properties.However,a universal growth approach is required...Organic–inorganic hybrid perovskite materials have been focusing more attention in the field of self-powered photodetectors due to their superb photoelectric properties.However,a universal growth approach is required and challenging to realize vertically oriented growth and grain boundary fusion of 2D and 3D perovskite grains to promote ordered carrier transport,which determines superior photoresponse and high stability.Herein,a general thermal-pressed(TP)strategy is designed to solve the above issues,achieving uniaxial orientation and single-grain penetration along the film thickness direction.It constructs the efficient channel for ordered carrier transport between two electrodes.Combining of the improved crystal quality and lower trap-state density,the quasi-2D and 3D perovskite-based self-powered photodetector devices(with/without hole transport layer)all exhibit giant and stable photoresponse in a wide spectrum range and specific wavelength laser.For the MAPbI_(3)-based self-powered photodetectors,the largest R_(λ) value is as high as 0.57 A W^(−1)at 760 nm,which is larger than most reported results.Meanwhile,under laser illumination(532 nm),the FPEA_(2)MA_(4)Pb_(5)I_(16)-based device exhibits a high responsivity(0.4 A W^(−1)) value,which is one of the best results in 2DRP self-powered photodetectors.In addition,fast response,ultralow detection limit,and markedly improved humidity,optical and heat stabilities are clearly demonstrated for these TP-based devices.展开更多
With the continuous growth of China's economy,financial opening to the outside world has become one of the important means to promote economic development.However,with the continuous acceleration of capital flow,t...With the continuous growth of China's economy,financial opening to the outside world has become one of the important means to promote economic development.However,with the continuous acceleration of capital flow,the problem of balance in and out is becoming increasingly prominent.Taking China's financial opening to the outside world as the research object,this paper discusses how China strategically achieves the balance of entry and exit in the field of financial opening to the outside world,and the impact of this balance.Through the quantitative analysis of China's financial opening to the outside world and foreign capital flows,it is found that China needs to strengthen the management of capital items and optimize the structure of capital flows in the process of financial opening to the outside world,to achieve the balance of financial flows in and out.As for the impact of the balance of access and access,the analysis of the impact mechanism shows that the financial opening and access and balance can improve the stability of the financial market,provide sufficient liquidity for the healthy development of the financial market,and alleviate financial risks.Such a strategy is of great practical significance for promoting the sustained and healthy development of China's economy.Therefore,based on the actual situation of China,this paper puts forward some relevant strategy suggestions to guide the practical operation of China's financial opening up.展开更多
Persistent illumination inevitably leads to the formation of Pb^(0)and I^(0)species in perovskite film,serving as non-radiative recombination centers and thus limiting the process of the commercial application.Herein,...Persistent illumination inevitably leads to the formation of Pb^(0)and I^(0)species in perovskite film,serving as non-radiative recombination centers and thus limiting the process of the commercial application.Herein,we propose a redox strategy to dynamically eliminate the defective Pb^(0)and I^(0)generated during device operation using polyoxometalate(POM)as an additive.Benefiting from the reversible W^(5+/6+)redox activity and the structural stability when accepting and donating electrons from perovskite film,POMs play a role of the redox shuttle that oxidizes Pb^(0)into Pb^(2+)and reduces I^(0)into I^(-),consequently inhibiting the formation of Pb^(0)and I^(0)species and reducing the film defects,which benefits the improvement of stability and performance.As a result,the efficiency of carbon-based all-inorganic CsPbI_(2)Br cell is significantly improved to 15.12% and the efficiency of the organic-inorganic hybrid(Cs_(0.05)MA_(0.05)FA_(0.9))Pb(I_(0.93)Br_(0.07))_(3)cell is also increased to 24.20%.More importantly,the target device shows superior stability under air conditions after storage for 1500 h,high temperature after 750 h,and persistent irradiation over200 h,respectively,providing a new method for efficient and stable perovskite solar cells.展开更多
Partitioning of soil organic matter for particulate organic carbon(POC)and mineral-associated organic carbon(MAOC)is essential to understand carbon(C)storage under climate change,given their distinct properties and re...Partitioning of soil organic matter for particulate organic carbon(POC)and mineral-associated organic carbon(MAOC)is essential to understand carbon(C)storage under climate change,given their distinct properties and response to warming.The mechanisms underlying warming-induced changes in C pools in black soils(Mollisols)remain unknown,owing to the stability of C pools and the complexity of their associated microbial communities.This study elucidates POC and MAOC contents and their microbial controls in black soils along a mean annual temperature(MAT)gradient from 0.6 to 7.3℃.The POC content(3.3-17 g kg^(−1))increased with MAT,while MAOC content(33-60 g kg^(−1))decreased,indicating accelerated C turnover with warming.Higher MAT shifted the bacterial communities from K-to r-strategies,aligning with increased POC content.The dominance of r-strategists facilitated rapid utilization and mineralization of organic compounds(e.g.,mainly with low C/N ratio),reducing MAOC and increasing POC through sustained plant residue inputs.This shift towards r-strategists also corresponded with increased abundance of saprotrophic fungi and stronger bacteria-saprotrophic fungi associations.Warming in colder regions may release available organic matter that saprotrophic fungi preferentially utilize over plant residues to minimize energy expenditure,decreasing POC decomposition.Our findings suggest that integrating microbial r-/K-strategies help to elucidate these mechanisms and simplify the interpretation of temperature effects on the dynamics of two main functional pools of soil organic matter.展开更多
Gasoline compression ignition (GCI) is one of the most promising combustion concepts to maintain low pollutant emissions and high efficiency. However, low load combustion stability and firing in cold-start operations ...Gasoline compression ignition (GCI) is one of the most promising combustion concepts to maintain low pollutant emissions and high efficiency. However, low load combustion stability and firing in cold-start operations are two major challenges for GCI combustion. Strategies including negative valve overlap (NVO), advanced injection strategies, fuel reforming, and intake preheating have been proposed in order to solve these difficulties;however, the cold start is still an obstacle. The objective of this work is to study effective methods to achieve GCI engine cold start-up. This work combines NVO, in-cylinder fuel reforming, and intake preheating to achieve quick firing under cold-start conditions and the subsequent warmup conditions. The results show that start of injection (SOI) during the intake stroke yields the best fuel economy, and injection during the compression stroke has the potential to extend the low load limit. Furthermore, SOI during the NVO period grants the ability to operate under engine conditions with cold intake air and coolant. With highly reactive products made by in-cylinder fuel reforming and fast heat accumulation in the combustion chamber, the NVO injection strategy is highly appropriate for GCI firing. An additional assisted technical method, such as intake preheating, is required to ignite the first firing cycle for a cold-start process. With the combination of NVO, in-cylinder fuel reforming, and intake preheating, the GCI engine successfully started within five combustion cycles in the experiment. After the firing process, the engine could stably operate without further intake preheating;thus, this method is appropriate for engine cold-start and warm-up.展开更多
MXenes are under the spotlight due to their versatile physicochemical characteristics. Since their discovery in 2011, significant advancements have been achieved in their synthesis and application sectors. However, th...MXenes are under the spotlight due to their versatile physicochemical characteristics. Since their discovery in 2011, significant advancements have been achieved in their synthesis and application sectors. However, the spontaneous oxidation of MXenes, which is critical to its processing and product lifespan, has gotten less attention due to its chemical complexity and poorly understood oxidation mechanism. This perspective focuses on the oxidation stability of MXenes and addresses the most recent advancements in understanding and the possible countermeasures to limit the spontaneous oxidation of MXenes. A section is dedicated to the presently accessible methods for monitoring oxidation, with a discussion on the debatable oxidation mechanism and coherently operating factors that contribute to the complexity of MXenes oxidation. The current potential solutions for mitigating MXenes oxidation and the existing challenges are also discussed with prospects to prolong MXene's shelf-life storage and expand their application scope.展开更多
In a previous work(2018,Commun.Theor.Phys.70,795–802),a new compartment model for the spreading of rumors was introduced and analyzed.However,only the local asymptotic stability of this model was discussed.In the pre...In a previous work(2018,Commun.Theor.Phys.70,795–802),a new compartment model for the spreading of rumors was introduced and analyzed.However,only the local asymptotic stability of this model was discussed.In the present work,we first provide a rigorous mathematical analysis for the global asymptotic stability(GAS)of the above-mentioned rumor spreading model.By constructing suitable Lyapunov candidate functions,we obtain the GAS of a rumor-free(boundary)equilibrium point and a unique rumor-spreading(positive)equilibrium point.After that,we utilize the approach based on the Lyapunov candidate functions to study the GAS of another rumor spreading model with control strategies,which was proposed in(2022,Physica A 606,128157).As an important consequence,the GAS of the rumor spreading model with control strategies is determined fully without resorting to technical hypotheses used in the benchmark work.Lastly,the theoretical findings are supported by a set of illustrative numerical examples.The obtained results not only improve the ones constructed in the two abovementioned benchmark papers but also can be extended to study the global dynamics of other rumor propagation models in the context of both integer-order and fractional-order derivatives.展开更多
This paper considers the problem of simultaneous estimation of the system states and the strategy of commutation for a larger class of nonlinear switched systems.First,a hybrid high gain observer is considered to get ...This paper considers the problem of simultaneous estimation of the system states and the strategy of commutation for a larger class of nonlinear switched systems.First,a hybrid high gain observer is considered to get the exact estimation of the continuous states where the strategy of switching is previously known.Then,an extension to a larger class of nonlinear hybrid systems with arbitrary switching is made.Stability analysis is widely discussed for the two cases to provide a finite-time convergence of the estimation errors.The effectiveness of the proposed hybrid high gain observer has been proved by applying it to a quadruple tank process.展开更多
Comprehensive Summary The power conversion efficiencies(PCEs)of non-fullerene acceptor(NFA)-based organic solar cells(OSCs)have undergone an exciting development in recent years,but the poor intrinsic stability of exo...Comprehensive Summary The power conversion efficiencies(PCEs)of non-fullerene acceptor(NFA)-based organic solar cells(OSCs)have undergone an exciting development in recent years,but the poor intrinsic stability of exocyclic ethylene bridges in NFAs poses a significant challenge to their commercialization.In this work,we propose a new pyran-locking strategy that can stabilize the exocyclic ethylene bridge connecting the strong electron-deficient 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end group,based on which two dimerized NFAs(ITBIC-F and TBTBIC-F)with an A-D-π-A-π-D-A structure have been successfully synthesized with significantly improved chemical and photochemical stabilities in comparison with traditional NFAs without the ring-locked structure.The ITBIC-F and TBTBIC-F-based OSCs not only achieve promising PCEs of 13.03%and 10.01%,respectively,but also show good device stability;the ITBIC-F-based unencapsulated devices can retain 75%and 62%of their initial PCEs,respectively,under continuous heat(85°C)and light irradiation(LED,100 mW·cm^(–2))in a nitrogen atmosphere.展开更多
An extended car-following model with multiple delays is constructed to describe driver's driving behavior.Through stability analysis,the stability condition of this uncontrolled model is given.To dampen the negati...An extended car-following model with multiple delays is constructed to describe driver's driving behavior.Through stability analysis,the stability condition of this uncontrolled model is given.To dampen the negative impact of the driver's multiple delays(i.e.,stability condition is not satisfied),a novel control strategy is proposed to assist the driver in adjusting vehicle operation.The control strategy consists of two parts:the design of control term as well as the design of the parameters in the term.Bifurcation analysis is performed to illustrate the necessity of the design of parameters in control terms.In the course of the design of parameters in the control term,we improve the definite integral stability method to reduce the iterations by incorporating the characteristics of bifurcation,which can determine the appropriate parameters in the control terms more quickly.Finally,in the case study,we validate the control strategy by utilizing measured data and configuring scenario,which is closer to the actual traffic.The results of validation show that the control strategy can effectively stabilize the unstable traffic flow caused by driver's delays.展开更多
In this paper, transient stability analysis was focused on Hu-Liao HVDC and AC parallel transmission system. The Hu-Liao HVDC project was introduced;Simulation method and mathematic models of AC and DC systems were st...In this paper, transient stability analysis was focused on Hu-Liao HVDC and AC parallel transmission system. The Hu-Liao HVDC project was introduced;Simulation method and mathematic models of AC and DC systems were stu-died as well as corresponding regulators and controllers. The dynamic performance and the interaction between AC and DC systems during serious disturbance were researched by detail time-domain simulation. Comparison was also made under different operation schemes. The research will bring important and significant reference for further operation and stability control of Hu-Liao HVDC and AC system.展开更多
The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite network.DT-DVTR in the snapshot-based connectionoriented routing strategy is one o...The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite network.DT-DVTR in the snapshot-based connectionoriented routing strategy is one of the representative solutions,but it still has room for improvement in terms of routing stability.In this paper,we propose an improved scheme for connection-oriented routing strategy named the Minimal Topology Change Routing based on Collaborative Rules(MTCR-CR).The MTCR-CR uses continuous time static topology snapshots based on satellite status to search for intersatellite link(ISL)construction solutions that meet the minimum number of topology changes to avoid route oscillations.The simulation results in Beidou-3 show that compared with DT-DVTR,MTCR-CR reduces the number of routing changes by about 92%,the number of path changes caused by routing changes is about38%,and the rerouting time is reduced by approximately 47%.At the same time,in order to show our algorithm more comprehensively,the same experimental index test was also carried out on the Globalstar satellite constellation.展开更多
The purification of low-grade coal-bed methane is extremely important,but challenging,due to the very similar physical properties of CH_(4)and N2.Herein,we proposed a dual polarization strategy by employing triazine a...The purification of low-grade coal-bed methane is extremely important,but challenging,due to the very similar physical properties of CH_(4)and N2.Herein,we proposed a dual polarization strategy by employing triazine and polyfluoride sites to construct polar pores in COF materials,achieving the efficient separa-tion of CH_(4)from N2.As expected,the dual polarized F-CTF-1 and F-CTF-2 exhibit higher CH_(4)adsorption capacity and CH_(4)/N_(2)selectivity than CTF-1 and CTF-2,respectively.Especially,the CH4 uptake capacity and CH_(4)/N_(2)selectivity of F-CTF-2 is 1.76 and 1.42 times than that of CTF-2.This work not only developed promising COF materials for CH4/N_(2)separation,but also provided important guidance for the separation of other adsorbates with similar properties.展开更多
基金National Natural Science Foundation of China(Grant No.22005318,22379152)Western Young Scholars Foundations of Chinese Academy of Sciences+4 种基金Lanzhou Youth Science and Technology Talent Innovation Project(Grant No.2023-NQ-86,No.2023-QN-96)Lanzhou Chengguan District Science and Technology Plan Project(Grant No.2023-rc-4,2022-rc-4)Collaborative Innovation Alliance Fund for Young Science and Technology Worker(Grant No.HZJJ23-7)National Nature Science Foundations of Gansu Province(Grant No.21JR11RA020)Fundamental Research Funds for the Central Universities(Grant No.31920220073,31920230128)。
文摘Rechargeable aqueous zinc-ion batteries(AZIBs)exhibit appreciable potential in the domain of electrochemical energy storage.However,there are serious challenges for AZIBs,for instance zinc dendrite growth,hydrogen evolution reaction(HER),and corrosion side reactions.Herein,we propose a surface engineering modification strategy for coating the montmorillonite(MMT)layer onto the surface of the Zn anode to tackle these issues,thereby achieving high cycling stability for rechargeable AZIBs.The results reveal that the MMT layer on the surface of the Zn anode is able to provide ordered zincophilic channels for zinc ions migration,facilitating the reaction kinetics of zinc ions.Density functional theory(DFT)calculations and water contact angle(CA)tests prove that MMT@Zn anode exhibits superior adsorption capacity for Zn^(2+)and better hydrophobicity than the bare Zn anode,thereby achieving excellent cycling stability.Moreover,the MMT@Zn||MMT@Zn symmetric cell holds the stable cycling over 5600 h at 0.5 mA cm^(-2)and 0.125 m A h cm^(-2),even exceeding 1800 h long cycling under harsh conditions of 5 m A cm^(-2)and 1.25 m A h cm^(-2).The MMT@Zn||V_(2)O_(5)full cell reaches over 3000 cycles at 2 A g^(-1)with excellent rate capability.Therefore,this surface engineering modification strategy for enhancing the electrochemical performance of AZIBs represents a promising application.
文摘Existing literature has shown that the control force at the nose could cause dynamic instability for controlled projectiles. To lower the adverse impact on the dual-spin projectile with fixed canards under the premise of meeting guidance system requirements, the influence of control moment provided by a motor on the flight stability is analyzed in this paper. Firstly, the effect of the rolling movement on stability is analyzed based on the stability criterion derived using the Hurwitz stability theory. Secondly, the evaluation parameters combining the features of different control periods that could assess the variation of stability features after the motor torque are obtained. These effective formulas are used to indicate that, to reduce the flight instability risks, the stabilized rolling speed of roll speed keeping period should be as small as possible; the variation trend of motor torque during the rolling speed controlling period and the roll angle of the forward body during roll angle switching period are recommended corresponding to the projectile and trajectory characteristics. Moreover,detailed numerical simulations of 155 mm dual-spin projectile are satisfactory agreement with the theoretical results.
基金financially supported by National Natural Science Foundation of China(Nos.22122202,22072051,21972051)。
文摘Water splitting with proton exchange membrane water electrolyzers(PEMWE)is regarded as a promising pathway for sustainable hydrogen conversion.Additionally,oxygen evolution reaction(OER)is considered as the dominant factor during the whole process due to the sluggish kinetics.Among the catalysts,Rubased catalysts draw special attention because of their excellent activity and relatively low price.However,the limited stability impedes their further commercialization and tremendous efforts have been devoted to overcome this challenge.This review firstly introduces the basic mechanisms of OER.Then the evaluation protocols and techniques to investigate the stability of Ru-based catalysts are summarized.A detailed elucidation of the possible degradation mechanisms is also critically analyzed.Furthermore,effective strategies to design durable Ru-based catalysts for acidic OER are discussed.Such as heteroatom doping,phase and facet engineering,heterostructure building and support optimization.Finally,promises,perspectives and challenges in developing highly durable Ru-based catalysts for acidic OER are outlined.
基金the National Natural Science Foundation of China(NSFC,No.51872172,51972197)Natural Science Foundation of Shandong Province(ZR2019MEM021)Young Scholars Program of Shandong University.
文摘Organic–inorganic hybrid perovskite materials have been focusing more attention in the field of self-powered photodetectors due to their superb photoelectric properties.However,a universal growth approach is required and challenging to realize vertically oriented growth and grain boundary fusion of 2D and 3D perovskite grains to promote ordered carrier transport,which determines superior photoresponse and high stability.Herein,a general thermal-pressed(TP)strategy is designed to solve the above issues,achieving uniaxial orientation and single-grain penetration along the film thickness direction.It constructs the efficient channel for ordered carrier transport between two electrodes.Combining of the improved crystal quality and lower trap-state density,the quasi-2D and 3D perovskite-based self-powered photodetector devices(with/without hole transport layer)all exhibit giant and stable photoresponse in a wide spectrum range and specific wavelength laser.For the MAPbI_(3)-based self-powered photodetectors,the largest R_(λ) value is as high as 0.57 A W^(−1)at 760 nm,which is larger than most reported results.Meanwhile,under laser illumination(532 nm),the FPEA_(2)MA_(4)Pb_(5)I_(16)-based device exhibits a high responsivity(0.4 A W^(−1)) value,which is one of the best results in 2DRP self-powered photodetectors.In addition,fast response,ultralow detection limit,and markedly improved humidity,optical and heat stabilities are clearly demonstrated for these TP-based devices.
文摘With the continuous growth of China's economy,financial opening to the outside world has become one of the important means to promote economic development.However,with the continuous acceleration of capital flow,the problem of balance in and out is becoming increasingly prominent.Taking China's financial opening to the outside world as the research object,this paper discusses how China strategically achieves the balance of entry and exit in the field of financial opening to the outside world,and the impact of this balance.Through the quantitative analysis of China's financial opening to the outside world and foreign capital flows,it is found that China needs to strengthen the management of capital items and optimize the structure of capital flows in the process of financial opening to the outside world,to achieve the balance of financial flows in and out.As for the impact of the balance of access and access,the analysis of the impact mechanism shows that the financial opening and access and balance can improve the stability of the financial market,provide sufficient liquidity for the healthy development of the financial market,and alleviate financial risks.Such a strategy is of great practical significance for promoting the sustained and healthy development of China's economy.Therefore,based on the actual situation of China,this paper puts forward some relevant strategy suggestions to guide the practical operation of China's financial opening up.
基金financial support provided by the National Natural Science Foundation of China(62374105,62304124,52472259,62204098,22179051)the Special Fund of Taishan Scholar Program of Shandong Province(tsqnz20221141)。
文摘Persistent illumination inevitably leads to the formation of Pb^(0)and I^(0)species in perovskite film,serving as non-radiative recombination centers and thus limiting the process of the commercial application.Herein,we propose a redox strategy to dynamically eliminate the defective Pb^(0)and I^(0)generated during device operation using polyoxometalate(POM)as an additive.Benefiting from the reversible W^(5+/6+)redox activity and the structural stability when accepting and donating electrons from perovskite film,POMs play a role of the redox shuttle that oxidizes Pb^(0)into Pb^(2+)and reduces I^(0)into I^(-),consequently inhibiting the formation of Pb^(0)and I^(0)species and reducing the film defects,which benefits the improvement of stability and performance.As a result,the efficiency of carbon-based all-inorganic CsPbI_(2)Br cell is significantly improved to 15.12% and the efficiency of the organic-inorganic hybrid(Cs_(0.05)MA_(0.05)FA_(0.9))Pb(I_(0.93)Br_(0.07))_(3)cell is also increased to 24.20%.More importantly,the target device shows superior stability under air conditions after storage for 1500 h,high temperature after 750 h,and persistent irradiation over200 h,respectively,providing a new method for efficient and stable perovskite solar cells.
基金supported by the National Key Research and Development Program of China[Grant No.2022YFD1500202]Strategic Priority Research Program of the Chinese Academy of Sciences[Grant No.XDA28020202]+1 种基金China Postdoctoral Science Foundation[Grant No.2024M753332]the RUDN University Strategic Academic Leadership Program.
文摘Partitioning of soil organic matter for particulate organic carbon(POC)and mineral-associated organic carbon(MAOC)is essential to understand carbon(C)storage under climate change,given their distinct properties and response to warming.The mechanisms underlying warming-induced changes in C pools in black soils(Mollisols)remain unknown,owing to the stability of C pools and the complexity of their associated microbial communities.This study elucidates POC and MAOC contents and their microbial controls in black soils along a mean annual temperature(MAT)gradient from 0.6 to 7.3℃.The POC content(3.3-17 g kg^(−1))increased with MAT,while MAOC content(33-60 g kg^(−1))decreased,indicating accelerated C turnover with warming.Higher MAT shifted the bacterial communities from K-to r-strategies,aligning with increased POC content.The dominance of r-strategists facilitated rapid utilization and mineralization of organic compounds(e.g.,mainly with low C/N ratio),reducing MAOC and increasing POC through sustained plant residue inputs.This shift towards r-strategists also corresponded with increased abundance of saprotrophic fungi and stronger bacteria-saprotrophic fungi associations.Warming in colder regions may release available organic matter that saprotrophic fungi preferentially utilize over plant residues to minimize energy expenditure,decreasing POC decomposition.Our findings suggest that integrating microbial r-/K-strategies help to elucidate these mechanisms and simplify the interpretation of temperature effects on the dynamics of two main functional pools of soil organic matter.
基金the National Natural Science Foundation of China (91641203, 51476114, and 91741119)he National Key Research and Development Program of China (2017YFB0103400).
文摘Gasoline compression ignition (GCI) is one of the most promising combustion concepts to maintain low pollutant emissions and high efficiency. However, low load combustion stability and firing in cold-start operations are two major challenges for GCI combustion. Strategies including negative valve overlap (NVO), advanced injection strategies, fuel reforming, and intake preheating have been proposed in order to solve these difficulties;however, the cold start is still an obstacle. The objective of this work is to study effective methods to achieve GCI engine cold start-up. This work combines NVO, in-cylinder fuel reforming, and intake preheating to achieve quick firing under cold-start conditions and the subsequent warmup conditions. The results show that start of injection (SOI) during the intake stroke yields the best fuel economy, and injection during the compression stroke has the potential to extend the low load limit. Furthermore, SOI during the NVO period grants the ability to operate under engine conditions with cold intake air and coolant. With highly reactive products made by in-cylinder fuel reforming and fast heat accumulation in the combustion chamber, the NVO injection strategy is highly appropriate for GCI firing. An additional assisted technical method, such as intake preheating, is required to ignite the first firing cycle for a cold-start process. With the combination of NVO, in-cylinder fuel reforming, and intake preheating, the GCI engine successfully started within five combustion cycles in the experiment. After the firing process, the engine could stably operate without further intake preheating;thus, this method is appropriate for engine cold-start and warm-up.
基金financial support by the National Natural Science Foundation of China (Grant No. U2004212 and 51802012)。
文摘MXenes are under the spotlight due to their versatile physicochemical characteristics. Since their discovery in 2011, significant advancements have been achieved in their synthesis and application sectors. However, the spontaneous oxidation of MXenes, which is critical to its processing and product lifespan, has gotten less attention due to its chemical complexity and poorly understood oxidation mechanism. This perspective focuses on the oxidation stability of MXenes and addresses the most recent advancements in understanding and the possible countermeasures to limit the spontaneous oxidation of MXenes. A section is dedicated to the presently accessible methods for monitoring oxidation, with a discussion on the debatable oxidation mechanism and coherently operating factors that contribute to the complexity of MXenes oxidation. The current potential solutions for mitigating MXenes oxidation and the existing challenges are also discussed with prospects to prolong MXene's shelf-life storage and expand their application scope.
文摘In a previous work(2018,Commun.Theor.Phys.70,795–802),a new compartment model for the spreading of rumors was introduced and analyzed.However,only the local asymptotic stability of this model was discussed.In the present work,we first provide a rigorous mathematical analysis for the global asymptotic stability(GAS)of the above-mentioned rumor spreading model.By constructing suitable Lyapunov candidate functions,we obtain the GAS of a rumor-free(boundary)equilibrium point and a unique rumor-spreading(positive)equilibrium point.After that,we utilize the approach based on the Lyapunov candidate functions to study the GAS of another rumor spreading model with control strategies,which was proposed in(2022,Physica A 606,128157).As an important consequence,the GAS of the rumor spreading model with control strategies is determined fully without resorting to technical hypotheses used in the benchmark work.Lastly,the theoretical findings are supported by a set of illustrative numerical examples.The obtained results not only improve the ones constructed in the two abovementioned benchmark papers but also can be extended to study the global dynamics of other rumor propagation models in the context of both integer-order and fractional-order derivatives.
文摘This paper considers the problem of simultaneous estimation of the system states and the strategy of commutation for a larger class of nonlinear switched systems.First,a hybrid high gain observer is considered to get the exact estimation of the continuous states where the strategy of switching is previously known.Then,an extension to a larger class of nonlinear hybrid systems with arbitrary switching is made.Stability analysis is widely discussed for the two cases to provide a finite-time convergence of the estimation errors.The effectiveness of the proposed hybrid high gain observer has been proved by applying it to a quadruple tank process.
基金the National Natural Science Foundation of China(Grant No.22175067).
文摘Comprehensive Summary The power conversion efficiencies(PCEs)of non-fullerene acceptor(NFA)-based organic solar cells(OSCs)have undergone an exciting development in recent years,but the poor intrinsic stability of exocyclic ethylene bridges in NFAs poses a significant challenge to their commercialization.In this work,we propose a new pyran-locking strategy that can stabilize the exocyclic ethylene bridge connecting the strong electron-deficient 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end group,based on which two dimerized NFAs(ITBIC-F and TBTBIC-F)with an A-D-π-A-π-D-A structure have been successfully synthesized with significantly improved chemical and photochemical stabilities in comparison with traditional NFAs without the ring-locked structure.The ITBIC-F and TBTBIC-F-based OSCs not only achieve promising PCEs of 13.03%and 10.01%,respectively,but also show good device stability;the ITBIC-F-based unencapsulated devices can retain 75%and 62%of their initial PCEs,respectively,under continuous heat(85°C)and light irradiation(LED,100 mW·cm^(–2))in a nitrogen atmosphere.
基金Project supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY20G010004)the Program of Humanities and Social Science of Education Ministry of China(Grant No.20YJA630008)+1 种基金the National Key Research and Development Program of China–Traffic Modeling,Surveillance and Control with Connected&Automated Vehicles(Grant No.2017YFE9134700)the K.C.Wong Magna Fund in Ningbo University,China。
文摘An extended car-following model with multiple delays is constructed to describe driver's driving behavior.Through stability analysis,the stability condition of this uncontrolled model is given.To dampen the negative impact of the driver's multiple delays(i.e.,stability condition is not satisfied),a novel control strategy is proposed to assist the driver in adjusting vehicle operation.The control strategy consists of two parts:the design of control term as well as the design of the parameters in the term.Bifurcation analysis is performed to illustrate the necessity of the design of parameters in control terms.In the course of the design of parameters in the control term,we improve the definite integral stability method to reduce the iterations by incorporating the characteristics of bifurcation,which can determine the appropriate parameters in the control terms more quickly.Finally,in the case study,we validate the control strategy by utilizing measured data and configuring scenario,which is closer to the actual traffic.The results of validation show that the control strategy can effectively stabilize the unstable traffic flow caused by driver's delays.
文摘In this paper, transient stability analysis was focused on Hu-Liao HVDC and AC parallel transmission system. The Hu-Liao HVDC project was introduced;Simulation method and mathematic models of AC and DC systems were stu-died as well as corresponding regulators and controllers. The dynamic performance and the interaction between AC and DC systems during serious disturbance were researched by detail time-domain simulation. Comparison was also made under different operation schemes. The research will bring important and significant reference for further operation and stability control of Hu-Liao HVDC and AC system.
基金supported by the National Key Research and Development Program of China(No.2020YFB1806000)。
文摘The high-speed movement of satellites makes it not feasible to directly apply the mature routing scheme on the ground to the satellite network.DT-DVTR in the snapshot-based connectionoriented routing strategy is one of the representative solutions,but it still has room for improvement in terms of routing stability.In this paper,we propose an improved scheme for connection-oriented routing strategy named the Minimal Topology Change Routing based on Collaborative Rules(MTCR-CR).The MTCR-CR uses continuous time static topology snapshots based on satellite status to search for intersatellite link(ISL)construction solutions that meet the minimum number of topology changes to avoid route oscillations.The simulation results in Beidou-3 show that compared with DT-DVTR,MTCR-CR reduces the number of routing changes by about 92%,the number of path changes caused by routing changes is about38%,and the rerouting time is reduced by approximately 47%.At the same time,in order to show our algorithm more comprehensively,the same experimental index test was also carried out on the Globalstar satellite constellation.
基金supported by National Key R&D Program of China(No.2022YFA1503300)National Natural Science Foundation of China(Nos.21978138,22035003)+1 种基金the Fundamental Research Funds for the Central Universities(Nankai University)the Haihe Laboratory of Sustainable Chemical Transformations(No.YYJC202101).
文摘The purification of low-grade coal-bed methane is extremely important,but challenging,due to the very similar physical properties of CH_(4)and N2.Herein,we proposed a dual polarization strategy by employing triazine and polyfluoride sites to construct polar pores in COF materials,achieving the efficient separa-tion of CH_(4)from N2.As expected,the dual polarized F-CTF-1 and F-CTF-2 exhibit higher CH_(4)adsorption capacity and CH_(4)/N_(2)selectivity than CTF-1 and CTF-2,respectively.Especially,the CH4 uptake capacity and CH_(4)/N_(2)selectivity of F-CTF-2 is 1.76 and 1.42 times than that of CTF-2.This work not only developed promising COF materials for CH4/N_(2)separation,but also provided important guidance for the separation of other adsorbates with similar properties.
