stability

摘要： The Riemann wave system has a fundamental role in describing waves in various nonlinear natural phenomena,for instance,tsunamis in the oceans.This paper focuses on executing the generalized exponential rational function approach and some numerical methods to obtain a distinct range of traveling wave structures and numerical results of the two-dimensional Riemann problems.The stability of obtained traveling wave solutions is analyzed by satisfying the constraint conditions of the Hamiltonian system.Numerical simulations are investigated via the finite difference method to verify the accuracy of the obtained results.To extract the approximation solutions to the underlying problem,some ODE solvers in FORTRAN software are applied,and outcomes are shown graphically.The stability and accuracy of the numerical schemes using Fourier’s stabilitymethod and error analysis,respectively,to increase the reassurance are investigated.A comparison between the analytical and numerical results is obtained and graphically provided.The proposed methods are effective and practical to be applied for solving more partial differential equations(PDEs).

摘要： Curcumin is a bioactive molecule with limited industrial application because of its instability and poor solubility in water.Herein,curcumin-loaded Pickering emulsion was produced using purified bacterial cellulose from fermented kombucha(KBC).The morphology,particle size,stability,rheological properties,and antioxidant activities of the curcumin-loaded Pickering emulsion were investigated.The fluorescence microscope and scanning electron microscopy images showed that the curcumin-loaded Pickering emulsion formed circular droplets with good encapsulation.The curcumin-load Pickering emulsion exhibited better stability under a wide range of temperatures,low p H,sunlight,and UV-365 nm than the free curcumin,indicating that the KBC after high-pressure homogenization improved the stability of the CPE.The encapsulated curcumin retained its antioxidant capacity and exhibited higher functional potential than the free curcumin.The study demonstrated that the KBC could be an excellent material for preparing a Pickering emulsion to improve curcumin stability and antioxidant activity.

摘要： In this paper, we investigated stability and bifurcation behaviors of a predator-prey model with Michaelis-Menten type prey harvesting. Sufficient conditions for local and global asymptotically stability of the interior equilibrium point were established. Some critical threshold conditions for transcritical bifurcation, saddle-node bifurcation and Hopf bifurcation were explored analytically. Furthermore, It should be stressed that the fear factor could not only reduce the predator density, but also affect the prey growth rate. Finally, these theoretical results revealed that nonlinear Michaelis-Menten type prey harvesting has played an important role in the dynamic relationship, which also in turn proved the validity of theoretical derivation.

摘要： The Chinese economy is estimated to have maintained a high growth rate of about 8 percent with the COVID-19 pandemic basically under control in 2021.At the same time,the triple pressures of demand contraction,supply shock,and weakening expectations gradually emerged as the quarterly economic growth rate endured an obvious downward slope,an indication that China’s economic development will face more difficulties in 2022.Therefore,the Central Economic Work Conference held in December 2021 noted that economic work should“prioritize stability while pursuing progress,”which set“stability”as the tone for economic development in 2022.

摘要： Perovskite solar cells (PSCs) employing formamidinium lead iodide (FAPbI_(3)) have shown high efficiency.However,operational stability has been issued due to phase instability of α phase FAPbI_(3) at ambient temperature.Excess precursors in the perovskite precursor solution has been proposed to improve not only power conversion efficiency (PCE) but also device stability.Nevertheless,there is a controversial issue on the beneficial effect on PCE and/or stability between excess FAI and excess PbI_(2).We report here extended X-ray absorption fine structure (EXAFS) of FAPbI_(3) to study local structural change and explain the effect of excess precursors on photovoltaic performance and stability.Perovskite films prepared from the precursor solution with excess PbI_(2)shows better stability than those from the one with excess FAI,despite similar PCE.A rapid phase transition from α phase to non-perovskite δ phase is observed from the perovskite film formed by excess FAI.Furthermore,the (Pb-I) bond distance evaluated by the Pb L_(III)-edge EXAFS study is increased by excess FAI,which is responsible for the phase transition and poor device stability.This work can provide important insight into local structure-stability relation in the FAPbI_(3)-based PSCs.

摘要： Introduction Atomically dispersed transition metals embedded in nitrogendoped carbons(M–N–C) represent a typical kind of platinum group-free(PGM-free) catalyst which is considered as a potential candidate for the cathode of proton-exchange membrane fuel cells(PEMFCs) [1–3]. Apart from their low cost, the advantage of the M–N–C catalysts over PGM is further underlined by their good poisoning-resistance to impurities in fossil-derived hydrogen, such as carbon monoxide and sulfur-containing compounds [4,5].

摘要： A multi-state dependent model is proposed for integrated pest management, which adopts different control methods at different thresholds. The sufficient conditions for the existence of order one periodic solution to the system are obtained by using differential equation geometry theory and successor function. Furthermore, we have discussed the existence of order-k (k ≥ 2) periodic solution by using series convergence. Besides we have proved the order one periodic solution is orbitally asymptotically stable under certain conditions with analogue of the Poincare criterion. Finally, numerical simulations are given to show the feasibility of our main results. Especially, the proved process of the existence of order one periodic solution shows that our method used in this paper is easier than the existing methods.

摘要： At present,the stability of the new generation of solar cells based on hybrid perovskites is the bottleneck for their practical applications.Photochemical effects,high temperature,ultraviolet light,humidity and other known or still unknown factors might cause reduction of effectiveness or even irreversible loss of materials properties due to decomposition of functional layers within perovskite solar cells(PSCs).These factors alone have a serious impact on each component of the device,while their combinations lead to much more complicated effects and consequences.This review focuses on the stability of PSCs and the degradation of the device in a humid environment.We assess the instability factors and deep-seated principles of evolution of the device structure in a humidity environment with the emphasis on the influence on their interrelations.The related solutions are reviewed from the perspective of the encapsulation,perovskite active layer,carrier transport layer and electrodes.Combined with the latest research,we believe that the waterproof strategy of PSCs requires either tight encapsulation or thorough modifications in the device itself.Therefore,it is important to develop feasible strategies to improve the overall device stability over humid according to the target characteristics of various devices.

摘要： Propane dehydrogenation(PDH) provides an alternative route for producing propylene. Herein, we demonstrates that h-BN is a promising support of Pt-based catalysts for PDH. The Pt catalysts supported on h-BN were prepared by an impregnation method using Pt(NH_(3))_(4)(NO_(3))_(2) as metal precursors. It has been found that the Pt/BN catalyst undergoing calcination and reduction is highly stable in both PDH reaction and coke-burning regeneration, together with low coke deposition and outstanding propylene selectivity(99%). Detailed characterizations reveal that the high coke resistance and high propylene selectivity of the Pt/BN catalyst are derived not only from the absence of acidity on BN support, but also from the calcination-induced and reduction-adjusted strong metal-support interaction(SMSI) between Pt and BN, which causes the partial encapsulation of Pt particles by BO_(x) overlayers. The BO_(x) overlayers can block the low-coordinated Pt sites and constrain Pt particles into smaller ensembles, suppressing side reactions such as cracking and deep dehydrogenation. Moreover, the BO_(x) overlayers can effectively inhibit Pt sintering by the spatial isolation of Pt during periodic reaction-regeneration cycles. In this work, the catalyst support for PDH is expanded to nonoxide BN, and the understanding of SMSI between Pt and BN will provide rational design strategy for BN-based catalysts.

摘要： On March 11,the closing meeting of the fifth session of the 13th National People’s Congress(NPC)was held,marking the end of the two sessions of 2022.As a key word,“stability”appeared 76 times in this year’s Government Work Report.The report emphasized“prioritizing stability while pursuing progress”,and forcefully implementing macro policies to stabilize the economy.This year will be very important because the 20th National Congress of the CPC will be held.Under this background,steady growth will have a special significance.Facing the triple pressure of“demand contraction supply shocks and weakening expectation”,on which part shall macro policies focus?How should companies seize opportunities?

摘要： Lambert W function has been found successful applications in stability analysis of time-delay systems. Though the associated stability criterion, the real part of a function resulted from the principal branch of Lambert W function is less than a given real number, works ectively with the help of Maple, Matlab or Mathematica, it is actually not easy to understandable because Lambert W function is not an elementary function. In this paper, new stability criteria have been derived from a careful investigation of the root location of Lambert W function, so that the asymptotical stability and robust stability of some time- delay systems checked by using LambertWfunction can now be tested simply by calculating elementary functions. In addition, the new stability criterion generalizes some existing criteria such as Hayes Theorem from real domain to complex domain.

摘要： [Abstract] This paper is aimed at analyzing an area power system. After detailedcalculationwe found it is necessary to control the transient stability of thus area powersystem. Based On to the characteristic of the area powersystema decentralied andintegrated Control mode is introduced to solve the problem. It is simple and can be easilyrealized to compare the valne of △P when fault occurs with thai of △P set.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.

摘要： Considering the whole impact of mechanical and rnelectrical system nonlinearities, the direct feedback rnlinearization (DFL) rncontrol strategy was used in the AC all-electrical rntank gun control system to achieve a completely rndynamic decoupling model. On the rnbasis of DEF, in order to reduce the effect of rnchanges in the system parameters and load torque, an rnadaptive wavelet neural network rncompensator to compensate for DEF error is proposed, rnwhich can reduce DEF control law reliance on the tank rngun system model,rnand further enhance the speed tracking performance, rnrobustness and adaptive capacity of AC tank gun rncontrol system. Computer rnsimulations show that the tracking accuracy is much rnbetter and the control system has strong adaptability rnand robustness.