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2898篇 您的检索式:关键字=STABILITY
    题名 作者 年代 出处 被引量
1Phase stability in high entropy alloys:Formation of solid-solution phase or amorphous phaseSheng GUO C.T. LIU 2011Progress in Natural Science:Materials International2011,21,6:91
2Global warming weakening the inherent stability of glaciers and permafrost显示文摘The Cryosphere has been undergoing a worldwide retreat, as seen in the decrease in the areal extent and volume of glaciers and in the areal extent of permafrost. This paper presents a systematic examination of the inherent stability changes of glaciers and permafrost caused by warming. Various study results suggest that over the past 30 years, the internal temperature of glaciers and permafrost exhibits an overall accelerating warming trend. The warming rate peaked in the mid-2000s and slowed slightly for several years afterward. In recent years, however, the warming rate has seemed to pick up again. The warming of glaciers and permafrost has exerted great impact on their stability, displayed as intensified melting,increased glacier surging, enlargement of supraglacial lakes, and increased permafrost degradation.Even without a future temperature increase, some glaciers will continue to shrink, and the number of surging glaciers will increase. The transition from low-temperature to high-temperature permafrost is a noticeable warning sign of a comprehensive degradation of permafrost. These results indicate that‘‘warming' glaciers and permafrost will exert significant impacts on the hydrology, ecology, and stability of engineering in cold regions.Yongjian Ding Shiqiang Zhang Lin Zhao Zhongqin Li Shichang Kang 2019Science Bulletin2019,64,4:37
3Conditional nonlinear optimal perturbation: Applications to stability, sensitivity, and predictability显示文摘Conditional nonlinear optimal perturbation (CNOP) is a nonlinear generalization of linear singular vector (LSV) and features the largest nonlinear evolution at prediction time for the initial perturbations in a given constraint. It was proposed initially for predicting the limitation of predictability of weather or climate. Then CNOP has been applied to the studies of the problems related to predictability for weather and climate. In this paper, we focus on reviewing the recent advances of CNOP's applications, which involves the ones of CNOP in problems of ENSO amplitude asymmetry, block onset, and the sensitivity analysis of ecosystem and ocean's circulations, etc. Especially, CNOP has been primarily used to construct the initial perturbation fields of ensemble forecasting, and to determine the sensitive area of target observation for precipitations. These works extend CNOP's applications to investigating the nonlinear dynamical behaviors of atmospheric or oceanic systems, even a coupled system, and studying the problem of the transition between the equilibrium states. These contributions not only attack the particular physical problems, but also show the superiority of CNOP to LSV in revealing the effect of nonlinear physical processes. Consequently, CNOP represents the optimal precursors for a weather or climate event; in predictability studies, CNOP stands for the initial error that has the largest negative effect on prediction; and in sensitivity analysis, CNOP is the most unstable (sensitive) mode. In multi-equilibrium state regime, CNOP is the initial perturbation that induces the transition between equilibriums most probably. Furthermore, CNOP has been used to construct ensemble perturbation fields in ensemble forecast studies and to identify sensitive area of target observation. CNOP theory has become more and more substantial. It is expected that CNOP also serves to improve the predictability of the realistic predictions for weather and climate events plays an increasingly important role in exploring the nonlinear dynamics of atmospheric, oceanic and coupled atmosphere-ocean system.DUAN WanSuo MU Mu 2009Science China Earth Sciences2009,52,7:32
4Stability Limitation and Analytical Evaluation of Voltage Droop Controllers for VSC MTDC显示文摘This paper presents a systematic analysis of DC voltage stability of a multi-terminal VSC-HVDC(MTDC)system,with the emphasis on a comparative study of the most ubiquitous droop control configurations.The paper introduces a general framework for the analysis of various droop control configurations employed in MTDC systems.This framework is then used to compare leading droop control configurations in terms of their impact on the relative stability,performance and robustness of the overall MTDC system.A generalized analytical MTDC model that contains detailed models of AC and DC system components is derived.Limitations imposed by DC power flow,DC inductor,cable modeling and AC network impedance on DC system stability are identified.Classical and multivariable frequency response analysis and eigenvalue analysis are applied to open-loop and closed-loop models to compare the stability and robustness of five leading droop controllers,with the focus on feedback signal selection and controller parameterization.This paper also proposes an active stabilizing controller,which takes the form of a modified constant power control,to enhance the controllability and robustness of the DC voltage control.Wenyuan Wang Mike Barnes Ognjen Marjanovic 2018CSEE Journal of Power and Energy Systems2018,4,2:34
5PHYSICAL MODELING FOR THE MECHANISMS OF BEAD FORMATION DEFECTS BASED ON THE STABILITY OF LIQUID METAL显示文摘Based on the theory of stability of the liquid metal under the action of surface tension,a physical mod- el is established for the mechanisms of the bead formation deferct’ humping’, which is generated during high - speed welding.A boundary function is introduced to correct the model,theoretical results got by the model correspond well with the experimental phenomena. A two - dimensional conducting model is adoopted in the simulation of the temperature field during high - speed welding.Finally, the factors acting upon the stability of liquid metal are analyzed.S. Y. Yin L. Feng J. Z. Ding and S. J. Chan( 1) Beijing Polytechnic University, Beijing 100022, China 2) National Key Laboratory of Advanced Wdlding Production Technology, HIT, Harbin 150001, China) 2000Acta Metallurgica Sinica(English Letters)2000,13,1:28
6Self-tuning virtual synchronous generator control for improving frequency stability in autonomous photovoltaic-diesel microgrids显示文摘This paper investigates the use of a virtual synchronous generator(VSG) to improve frequency stability in an autonomous photovoltaic-diesel microgrid with energy storage. VSG control is designed to emulate inertial response and damping power via power injection from/to the energy storage system. The effect of a VSG with constant parameters(CP-VSG) on the system frequency is analyzed. Based on the case study, self-tuning algorithms are used to search for optimal parameters during the operation of the VSG in order to minimize the amplitude and rate of change of the frequency variations. The performances of the proposed self-tuning(ST)-VSG, the frequency droop method, and the CP-VSG are evaluated by comparing their effects on attenuating frequency variationsunder load variations. For both simulated and experimental cases, the ST-VSG was found to be more efficient than the other two methods in improving frequency stability.Rongliang SHI Xing ZHANG Chao HU Haizhen XU Jun GU Wei CAO 2018Journal of Modern Power Systems and Clean Energy2018,6,3:27
7Hybrid Material of Graphene and Poly(3,4-ethyldioxythiophene)with High Conductivity,Flexibility,and Transparency显示文摘A novel hybrid material prepared from graphene and poly(3,4-ethyldioxythiophene)(PEDOT)shows excellent transparency,electrical conductivity,and good flexibility,together with high thermal stability and is easily processed in both water and organic solvents.Conductivities of the order of 0.2 S/cm and light transmittance of greater than 80%in the 4001800 nm wavelength range were observed for fi lms with thickness of tens of nm.Practical applications in a variety of optoelectronic devices are thus expected for this transparent and flexible conducting graphene-based hybrid material。Yanfei Xu Yan Wang Jiajie Liang Yi Huang Yanfeng Ma Xiangjian Wan Yongsheng Chen 2009Nano Research2009,2,4:23
8Adapting liposomes for oral drug delivery显示文摘Liposomes mimic natural cell membranes and have long been investigated as drug carriers due to excellent entrapment capacity, biocompatibility and safety. Despite the success of parenteral liposomes,oral delivery of liposomes is impeded by various barriers such as instability in the gastrointestinal tract,difficulties in crossing biomembranes, and mass production problems. By modulating the compositions of the lipid bilayers and adding polymers or ligands, both the stability and permeability of liposomes can be greatly improved for oral drug delivery. This review provides an overview of the challenges and current approaches toward the oral delivery of liposomes.Haisheng He Yi Lu Jianping Qi Quangang Zhu Zhongjian Chen Wei Wu 2019Acta Pharmaceutica Sinica B2019,9,1:23
9A Preliminary Study of the Gas Hydrate Stability Zone in the South China Sea显示文摘Based on the analysis of sea-bottom temperature and geothermal gradient, and by means of the phaseboundary curve of gas hydrate and the sea-bottom temperature versus water depth curve in the South China Sea, thispaper studies the temperature and pressure conditions for gas hydrate to keep stable. In a marine environment, methanehydrate keeps stable at water depths greater than 550 m in the South China Sea. Further, the thickness of the gas hydratestability zone in the South China Sea was calculated by using the phase boundary curve and temperature-depth equations.The result shows that gas hydrate have a better perspective in the southeast of the Dongsha Islands, the northeast of theXisha Islands and the north of the Nansha Islands for thicker stability zones.JIN Chunshuang WANG Jiyang 2002Acta Geologica Sinica(English Edition)2002,76,4:21
10Deformation reinforcement theory and its application to high arch dams显示文摘In this paper,the deformation reinforcement theory(DRT) proposed by the authors is elaborated with a new definition of instability that an elasto-plastic structure is not stable if it cannot satisfy simultaneously equilibrium condition,kinematical admissibility and constitutive equations under the prescribed loading.Starting from the definition,a proof is established to the principle of minimum plastic complementary energy for failured structures.It is revealed that the principle of mini-mum plastic complementary energy results in relaxed constitutive equations,especially,yield conditions.It is demonstrated with case studies that many key issues in arch dam design,e.g.,global stability,dam-toe reinforcement,dam-toe cracking,dam-abut-ment reinforcement,can be well solved within the framework of the deformation reinforcement theory.The structural global stability can be described by the curve of the plastic complementary energy vs overloading factor.The unbalanced-forces obtained by elasto-plastic FEM can be used as the basis of analysis of global stability,dam-heel cracking,dam-toe anchorage and reinforcement of faults of high arch dams and their foundations.YANG Qiang,LIU YaoRu,CHEN YingRu & ZHOU WeiYuan State Key Laboratory of Hydroscience and Hydraulic Engineering,Tsinghua University,Beijing 100084,China 2008Science China(Technological Sciences)2008,51,S2:21
11A chlorinated copolymer donor demonstrates a 18.13% power conversion efficiency显示文摘The rapid development of low-bandgap(LBG)nonfullerene acceptors and wide-bandgap(WBG)copolymer donors in recent years has boosted the power conversion efficiency(PCE)of organic solar cells(OSCs)to the 18%level[1−21].The commercialization of OSCs is highly expected.However,critical issues like the cost and the stability also determine whether OSCs can enter the market or not[22].Jianqiang Qin Lixiu Zhang Chuantian Zuo Zuo Xiao Yongbo Yuan Shangfeng Yang Feng Hao Ming Cheng Kuan Sun Qinye Bao Zhengyang Bin Zhiwen Jin and Liming Ding 2021Journal of Semiconductors2021,42,1:19
12NONLINEAR STABILITY OF NATURAL RUNGE-KUTTA METHODS FOR NEUTRAL DELAY DIFFERENTIAL EQUATIONS显示文摘This paper first presents the stability analysis of theoretical solutions for a class of nonlinear neutral delay-differential equations (NDDEs). Then the numerical analogous results, of the natural Runge-Kutta (NRK) methods for the same class of nonlinear NDDEs, are given. In particular, it is shown that the (k, l)-algebraic stability of a RK method for ODEs implies the generalized asymptotic stability and the global stability of the induced NRK method.Cheng-jian Zhang(Department of Mathematics, Huazhong University of Science and Technology, Wuhan 430074, Hubei, P. R. China) 2002Journal of Computational Mathematics2002,20,6:18
13NONLINEAR STOCHASTIC DYNAMICS: A SURVEY OF RECENT DEVELOPMENTS显示文摘This paper provides an overview of significant advances in nonlinearstochastic dynamics during the past two decades, including random response, stochas-tic stability, stochastic bifurcation, first passage problem and nonlinear stochasticcontrol. Topics for future research are also suggested.朱位秋 蔡国强 2002Acta Mechanica Sinica2002,18,6:18
14A new method for judging the computational stability of the difference schemes of nonlinear evolution equations显示文摘For the non-conservative difference schemes of nonlinear evolution equations with aperiodic boundary conditions, taken one-dimensional nonlinear advection equation as an example, a new method for judging the computational stability is given. It is proved to be practical and effective through several numerical examples. The stability criteria obtained by this method are really the necessary conditions of computational stability.LIN Wantao Jl Zhongzhen WANG Bin YANG Xiaozhong 2000Chinese Science Bulletin2000,45,15:18
15Exponential stability and periodic solutions of delayed cellular neural networks显示文摘A set of criteria are presented for the global exponential stability and the existence of periodic solutions of delayed cellular neural networks (DCNNs) by constructing suitable Lyapunov function-als, introducing many parameters qij* , rij* , qij, rij∈ R and wi>0 (i, j = 1, 2, …, n) and combining them with the elementary inequality 2ab≤a2 + b2 technique. These criteria have important significance in the design and applications of globally stable DCNNs and periodic oscillatory DCNNs. In addition, the results in literature are extended and improved. Two examples are given to illustrate the theory.曹进德 2000Science China(Technological Sciences)2000,43,3:17
16PERIODIC VIBRO-IMPACTS AND THEIR STABILITY OF A DUAL COMPONENT SYSTEM显示文摘The coexisting periodic impacting motions and their multiplicity ofa kind of dual component systems under harmonic excitation are analytically derived.The stability condition of a periodic impacting motion is given by analyzing the prop-agation of small, arbitrary perturbation from that motion. In numerical simulations,the periodic impacting motions are classified according to the system states beforeand after an impact. The numerical results show that there exist many types ofvibro-impacts and the bifurcation of periodic vibro-impacts is not smooth.金栋平 胡海岩 1997Acta Mechanica Sinica1997,13,4:17
17Probabilistic stability analyses of undrained slopes by 3D random fields and finite element methods显示文摘A long slope consisting of spatially random soils is a common geographical feature. This paper examined the necessity of three-dimensional(3 D) analysis when dealing with slope with full randomness in soil properties. Although 3 D random finite element analysis can well reflect the spatial variability of soil properties, it is often time-consuming for probabilistic stability analysis. For this reason, we also examined the least advantageous(or most pessimistic) cross-section of the studied slope. The concept of'most pessimistic' refers to the minimal cross-sectional average of undrained shear strength. The selection of the most pessimistic section is achievable by simulating the undrained shear strength as a 3 D random field. Random finite element analysis results suggest that two-dimensional(2 D) plane strain analysis based the most pessimistic cross-section generally provides a more conservative result than the corresponding full 3 D analysis. The level of conservativeness is around 15% on average. This result may have engineering implications for slope design where computationally tractable 2 D analyses based on the procedure proposed in this study could ensure conservative results.Yong Liu Wengang Zhang Lei Zhang Zhiren Zhu Jun Hu Hong Wei 2018Geoscience Frontiers2018,9,6:17
18Recent development of casing treatments for aeroengine compressors显示文摘Casing treatment is a mature stabilization technique which has been widely applied on aero-engines for modern aircrafts and turbo-chargers for automobiles. After the investigations of half century since the 1960 s, this technique has been well developed for various configurations with different effectiveness. From the perspective of stabilization mechanism, this paper roughly categorizes the configurations of casing treatment into two types: traditional ones which work by affecting the flow structure of blade tip region; a novel one named as Stall Precursor-Suppressed(SPS) casing treatment. The effectiveness of both types will be demonstrated for their applications on axial compressors and centrifugal compressors with uniform or distorted inlet. And the stabilization mechanism of casing treatments for regular types and SPS one will also be explained respectively. In addition, this review will summarize the methodologies of casing treatments with the numerical simulations for regular grooved configurations and the eigenvalue approach for SPS casing treatment.Looking forward to the future of compressor stabilization, casing treatment technique will still exist as a general and inexpensive option, and the exploration for its effectiveness and mechanism will be deeper with the development of computational fluid dynamics and advanced measurement techniques.Xiaofeng SUN Xu DONG Dakun SUN 2019Chinese Journal of Aeronautics2019,32,1:16
19The asymptotic stability of theoretical and numerical solutions for systems of neutral multidelay-differential equations显示文摘The asymptotic stability of theoretical and numerical solutions for neutral multidelay\|differential equations (NMDEs) is dealt with. A sufficient condition on the asymptotic stability of theoretical solutions for NMDEs is obtained. On the basis of this condition, it is proved that A\|stability of the multistep Runge\|Kutta methods for ODEs is equivalent to NGP\- k \|stability of the induced methods for NMDEs.张诚坚 周叔子 1998Science China Mathematics1998,41,11:16
20Overview of problems in large-scale wind integrations显示文摘Wind power has been developing rapidly in major countries in the past 10 years.The distinct static and dynamic characteristics of output power compared with conventional generations pose significant challenges on power system adequacy and stability and constraints on the penetration level of wind power in power systems.Based on the uniqueness of wind power versus conventional generations,we discuss its implications on power system adequacy and stability and propose basic solutions for facilitating largescale integrations of wind power into the power system.Xiaoming YUAN 2013Journal of Modern Power Systems and Clean Energy2013,1,1:16
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