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Two-dimensional Hurwitz-Schur stability test of linear systems with interval delays
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作者 Qina Gao Ying Zhu Yang Xiao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2013年第4期666-673,共8页
It is difficult to determine the stability of linear systems with interval delays (LID systems) because the roots of the characteristic polynomials of the systems are continuous and vary in a complex plane with the ... It is difficult to determine the stability of linear systems with interval delays (LID systems) because the roots of the characteristic polynomials of the systems are continuous and vary in a complex plane with the delay. To solve the problem, this paper develops a stability test of LID systems by resorting to 2-D hybrid polynomials and 2-D Hurwitz-Schur stability. Comparing with the existing test approaches for LID systems, the proposed 2-D Hurwitz-Schur stability test is easy to apply, and can obtain closed form constraint conditions for system parameters. This paper proposes some theorems as sufficient conditions for the stability of LID systems, and also reveals that recent results about the stability test of linear systems with any delays (LAD systems) are not suitable for LID systems because they are very conservative for the stability of LID systems. 展开更多
关键词 time-delay system quasipolynomial stability test 2-D Hurwitz-Schur stability.
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A new nonparametric stability test with an application to major Chinese macroeconomic time series
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作者 CAI Nan CAI Zong-wu FANG Ying 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2013年第1期1-16,共16页
In this paper, we propose a new test for testing the stability in macroeconomic time series, based on the LASSO variable selection approach and nonparametric estimation of a time-varying model. The wild bootstrap is e... In this paper, we propose a new test for testing the stability in macroeconomic time series, based on the LASSO variable selection approach and nonparametric estimation of a time-varying model. The wild bootstrap is employed to obtain its data-dependent critical values. We apply the new method to test the stability of bivariate relations among 92 major Chinese macroeconomic time series. We find that more than 70% bivariate relations are significantly unstable. 展开更多
关键词 LASSO stability test time-varying coefficients model wild bootstrap.
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Predicting stability of integrated circuit test equipment using upper side boundary values of normal distribution
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作者 Zhan Wenfa Hu Xinyi +3 位作者 Zheng Jiangyun Yu Chuxian Cai Xueyuan Zhang Lihua 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2024年第2期85-93,共9页
In response to the growing complexity and performance of integrated circuit(IC),there is an urgent need to enhance the testing and stability of IC test equipment.A method was proposed to predict equipment stability us... In response to the growing complexity and performance of integrated circuit(IC),there is an urgent need to enhance the testing and stability of IC test equipment.A method was proposed to predict equipment stability using the upper side boundary value of normal distribution.Initially,the K-means clustering algorithm classifies and analyzes sample data.The accuracy of this boundary value is compared under two common confidence levels to select the optimal threshold.A range is then defined to categorize unqualified test data.Through experimental verification,the method achieves the purpose of measuring the stability of qualitative IC equipment through a deterministic threshold value and judging the stability of the equipment by comparing the number of unqualified data with the threshold value,which realizes the goal of long-term operation monitoring and stability analysis of IC test equipment. 展开更多
关键词 K-means clustering algorithm the upper side boundary of normal distribution THRESHOLD integrated circuit(IC)test equipment stability analysis
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Experimental study of pavement performance of basalt fiber-modified asphalt mixture 被引量:17
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作者 范文孝 康海贵 郑元勋 《Journal of Southeast University(English Edition)》 EI CAS 2010年第4期614-617,共4页
To discuss the pavement performance of basalt fiber-modified asphalt mixtures,the optimum dosages of asphalt and fibers are studied by the Marshall test and the rutting test.The results demonstrate that the optimum do... To discuss the pavement performance of basalt fiber-modified asphalt mixtures,the optimum dosages of asphalt and fibers are studied by the Marshall test and the rutting test.The results demonstrate that the optimum dosages of asphalt and fibers are 4.63% and 0.3%,respectively.Then the pavement performances of basalt(polyester,xylogen)fiber-modified asphalt mixtures are investigated through high temperature stability tests,water stability tests and low temperature crack resistance tests.It indicates that the pavement performances of the fiber-modified asphalt mixtures such as rutting dynamic stability,freezing splitting tensile strength,low temperature crack resistance and so on are improved compared with control asphalt mixture.The results show that the pavement performances of asphalt mixtures can be improved by fiber-modifiers.Besides,the improvement effects of basalt fiber are superior to polyester fiber and xylogen fiber. 展开更多
关键词 asphalt mixture basalt fiber Marshall test high temperature stability test pavement performance
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Methane dehydroaromatization with periodic CH_4-H_2 switch:A promising process for aromatics and hydrogen 被引量:6
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作者 Changyong Sun Guangzong Fang +7 位作者 Xiaoguang Guo Yuanli Hu Shuqi Ma Tianhua Yang Jie Han Hao Ma Dali Tan Xinhe Bao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2015年第3期257-263,共7页
Long-term stability test of Mo/HZSM-5-N catalysts(HZSM-5-N stands for nano-sized HZSM-5) in methane dehydroaromatization(MDA)reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 100... Long-term stability test of Mo/HZSM-5-N catalysts(HZSM-5-N stands for nano-sized HZSM-5) in methane dehydroaromatization(MDA)reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics(i.e.benzene and naphthalene) exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity. 展开更多
关键词 methane dehydroaromatization(MDA) periodic CH4-H2switch long-term stability test coke deposition REGENERATION
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Velocity plus displacement equivalent force control for real-time substructure testing 被引量:1
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作者 Zhou Huimeng D.Wagg Wang Tao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期87-102,共16页
This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 fee... This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological(MR) damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions. 展开更多
关键词 real-time substructure test EFC velocity/displacement control newmark-β method stability
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Technological Valorization of Algerian Dates Downgraded from <i>Deglet Nour</i>Variety to Semi-Candied Dates in Dates Syrup
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作者 Férial Aziza Benyahia-Krid Elheyfa Khemissat +4 位作者 O. Aissaoui Zitoun Kaouther Djafri Meriem Bergouia Batoul Meghzili Lamia El-Mechta 《Food and Nutrition Sciences》 2021年第6期627-642,共16页
The objective of this study is the valorization of downgraded dates from a high Algerian date variety <span style="font-family:Verdana;"><i></i></span><i><i><span style... The objective of this study is the valorization of downgraded dates from a high Algerian date variety <span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">Deglet Nour</span></i><i><span style="font-family:Verdana;"></span></i></i><span style="font-family:;" "=""><span style="font-family:Verdana;">, locally called “</span><span style="font-family:Verdana;">h’chef</span><span style="font-family:Verdana;">”. The work starts with the implementation of a food formulation of semi-candied dat</span></span><span style="font-family:Verdana;">es in syrup extracted from dates. This formulation was based on dehydration-impregnation by immersion (D.I.I.). The downgraded dates were cleaned, cut, blanched, and then immersed in date syrups with increasing differential</span><span style="font-family:Verdana;"> concentrations in Brix degrees: 65</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">, 70</span><span style="font-family:Verdana;">°</span><span style="font-family:;" "=""> <span style="font-family:Verdana;">and</span><span style="font-family:Verdana;"> 75</span></span><span style="font-family:Verdana;">°</span><span style="font-family:;" "=""><span style="font-family:Verdana;">. The chosen date/syrup immersion ratio is 1:2 (w/w). The obtained semi-candied dates were the subject of physicochemical and sensory analyses. The characterization of the downgraded dates before immersion showed high sugar content with a rate </span><span style="font-family:Verdana;">52.67</span><span style="font-family:Verdana;"> g% g of dry matter and low water content (14%) which favors their use in semi-candied products. The </span><span style="font-family:Verdana;">physico-chemical</span> <span style="font-family:Verdana;">analyses</span><span style="font-family:Verdana;"> results of the three semi-candied dates products show an increase in their final sugar content, </span></span><span style="font-family:Verdana;"><i></i></span><i><i><span style="font-family:Verdana;">i.e.</span></i><i><span style="font-family:Verdana;"></span></i></i><span style="font-family:Verdana;"> from 53.55% to 60.78% and in ashes between 1</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">76 p.cent and 1</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">94 p.cent. On the other hand, sensory analysis results confirm that the semi-candied dates with a syrup of 75</span><span style="font-family:Verdana;">°</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> Brix present the most appreciated and preferable organoleptic characteristics than the other variables. Finally, following appertisation, the stability test </span><span style="font-family:Verdana;">reveal</span></span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> good microbiological quality (100</span><span style="font-family:Verdana;">°</span><span style="font-family:Verdana;">C for 20 minutes) of the three (3) semi-candied formulations of dates.</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> Thus, the valorization of the “</span><span style="font-family:Verdana;">h’chef</span><span style="font-family:Verdana;">” as sorting gap <i></i></span><i><i><span style="font-family:Verdana;">Deglet Nour</span></i></i></span><span style="font-family:Verdana;"> date allowed its transformation into semi-candied dates, stable, appreciable on the organoleptic side. This new formulation could constitute a value-added product if eventually manufactured on an industrial scale, mainly in southern Algeria.</span> 展开更多
关键词 Phoenix dactylifera L. Downgraded Dates Food Formulation Osmotic Dehydration stability Test
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Recent Advances in Stability Improvement Strategies of M-N_(x)/C Catalysts Towards Oxygen Reduction Reaction
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作者 Xiaolong Jia Qinglei Meng +5 位作者 Ruixue Zheng Xiaohui Liu Yaling Zhao Changpeng Liu Meiling Xiao Wei Xing 《Renewables》 2023年第6期694-719,共26页
Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbo... Although fuel cells possess advantages of high energy conversion efficiency and zero-carbon emission,their large-scale commercialization is restricted by expensive and scarce platinum(Pt)catalysts.Metal-nitrogen-carbon(M-Nx/C)catalysts are hailed as the most promising candidates to replace Pt due to their considerable oxygen reduction reaction(ORR)activity and low cost.Despite tremendous progress in terms of active site identification and activity improvement being achieved in the past few decades,the M-Nx/C catalysts still suffer from insufficient durability,which drastically limits their practical application.In this regard,understanding degradation mechanisms and customizing stabilization strategies are of significant importance yet challengeable.In this review,we summarize the recent advances in the stability improvement of M-Nx/C catalysts.The stability test protocols of the M-Nx/C are firstly introduced.Subsequently,with the combination of advanced ex situ and in situ characterization techniques and density functional theory calculation,we present a comprehensive overview of the main degradation mechanisms during ORR process.Aiming at these deactivation issues,a variety of novel improvement strategies are developed to enhance the stability of M-Nx/C.Finally,the current challenges and prospects to design highly stable M-Nx/C catalysts are also proposed. 展开更多
关键词 oxygen reduction reaction M-Nx/C catalysts stability test protocols degradation mechanisms stability improvement strategies
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Stability test of fractional-delay systems via integration 被引量:7
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作者 WANG ZaiHua DU MaoLin SHI Min 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2011年第10期1839-1846,共8页
This paper focuses on the stability testing of fractional-delay systems. It begins with a brief introduction of a recently reportedalgorithm, a detailed demonstration of a failure in applications of the algorithm and ... This paper focuses on the stability testing of fractional-delay systems. It begins with a brief introduction of a recently reportedalgorithm, a detailed demonstration of a failure in applications of the algorithm and the key points behind the failure. Then,it presents a criterion via integration, in terms of the characteristic function of the fractional-delay system directly, for testingwhether the characteristic function has roots with negative real parts only or not. As two applications of the proposed criterion,an algorithm for calculating the rightmost characteristic root and an algorithm for determining the stability switches, are proposed.The illustrative examples show that the algorithms work effectively in the stability testing of fractional-delay systems. 展开更多
关键词 fractional-order derivative time delay stability test characteristic root
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Improved 2-D Stability Margin Test for 2-D Discrete Systems 被引量:3
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作者 XIAO Yang\ DU Xiyu Institute of Information Science, Northern Northern Jiaotong University, Beijing, 100044 Rolf Unbehuen is with Lehrstuhl f Allgemeine und Theoretische Elektrotechnik UniversitT Erlangen Nrnberg, Cauerstr.7, 91058, Germany 《Systems Science and Systems Engineering》 CSCD 1998年第2期100-105,共6页
An improved 2 D stability margin test and its algorithm for 2 D discrete systems are proposed.The stability margin test procedure can be slmplified by using the inner term polynomials of B(z 1,z 2) to construct a ma... An improved 2 D stability margin test and its algorithm for 2 D discrete systems are proposed.The stability margin test procedure can be slmplified by using the inner term polynomials of B(z 1,z 2) to construct a margin test table.Different from other well known 2 D stability margin test algorithms,the new approach can directly obtain the stability margin. 展开更多
关键词 D discrete systems 2 D stability margin test test theorems and algorithm
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Hydrothermal synthesis and characterization of Dy-doped CeVO_(4) nanorods used for photodegradation of methylene blue and rhodamine B
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作者 Anukorn Phuruangrat Titipun Thongtem SomchaiThongtem 《Journal of Rare Earths》 SCIE EI CAS CSCD 2021年第10期1211-1216,I0002,共7页
Pure CeVO_(4) and Dy-doped CeVO_(4) nanorods containing different weight contents of Dy dopant were synthesized by hydrothermal method.Effect of Dy dopant on photodegradation of methylene blue(MB)and rhodamine B(RhB) ... Pure CeVO_(4) and Dy-doped CeVO_(4) nanorods containing different weight contents of Dy dopant were synthesized by hydrothermal method.Effect of Dy dopant on photodegradation of methylene blue(MB)and rhodamine B(RhB) was evaluated under UV light irradiation within 80 min.Pure CeVO_(4) and Dydoped CeVO_(4) nanorods were characterized by X-ray diffraction(XRD),Raman spectroscopy,transmission electron microscopy(TEM) and UV-visible spectroscopy.In this research,CeVO_(4) nanorods are tetragonal phase with the detection of main peak shift after being doped with Dy.The length of nanorods is deceased from 50 to 200 nm for pure CeVO_(4) to 50-100 nm for 3% Dy-doped CeVO_(4).Photodegradation of MB and RhB by CeVO_(4) nanorods under UV light irradiation is improved by Dy-dopant that plays the role in accepting electrons and reducing electron-hole recombination.MB and RhB solutions degraded by 3% Dy-doped CeVO_(4) nanorods was 94% and 93% within 80 min,respectively. 展开更多
关键词 Dy-doped CeVO4 nanorods Photocatalysis Spectroscopy Radical trapping test Photocatalytic stability test Rare earths
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