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Journal of Materials Science & Technology 2019年第1期35卷 192-200页

作者： Q.Wen W.Y.Li W.B.Wang F.F.Wang Y.J.Gao V.Patel State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding Technologies Northwestern Polytechnical University China FSW Center China Academy of Launch Vehicle Technology Beijing Institute of Astronautical Systems Engineering Capital Aerospace Machinery Company Pandit Deendayal Petroleum University

Stationary shoulder friction stir lap welding(SSFSLW) was employed to weld 2024 aluminum alloy. A coupled Eulerian-Lagrangian(CEL) model was developed to investigate the lap interface behavior during SSFSLW. Numerical results of material movement and equivalent plastic strain were in good agreement with the experimental work. With increasing welding speed, the distances from the hook tip to the top surface of the upper workpiece on the retreating side(RS) and the advancing side(AS) increase, while the distance between two wave-shaped alclads decreases. A symmetric interface bending is observed on the AS and the RS during plunging, while the interface bending on the AS is bigger than that on the RS during welding. The peak temperature of the interface on the AS is higher than that on the RS. The equivalent plastic strain gradually increases as the distance to the weld center decreases, and its peak value is obtained near the bottom of the weld.

关键词： Stationary shoulder friction stir lap welding Coupled Eulerian-Lagrangian Temperature field Material distribution Equivalent plastic strain

Power quality monitoring and evaluation in power systems under non-Stationary conditions using wavelet packet transform

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High Voltage 2019年第3期4卷 186-196页

作者： Panagiotis A.Karafotis Pavlos S.Georgilakis National Technical University of Athens(NTUA) School of Electrical and Computer Engineering9 Iroon Polytechniou StreetAthensGreece

The purpose of this paper is twofold:(i)to propose a methodology to accurately evaluate power quality indices,and(ii)to highlight the importance of power quality monitoring services at different voltage levels of three-phase power systems.The proposed methodology is based on wavelet packet transform(WPT)and is able to perform power quality analysis in three-phase power systems operating under Stationary and non-Stationary conditions,in the presence of both harmonics and unbalance.Several test cases are examined:synthetic voltage and current waveforms including noise,simulated test systems,a modified IEEE 13-bus test feeder,as well as experimental tests.The obtained results in all cases demonstrate the accuracy and the effectiveness of the proposed WPT method and its superiority over fast Fourier transform to accurately evaluate power quality indices in case of non-Stationary disturbances.

关键词： power Stationary transform

新型吡咯烷键合反相高效液相色谱固定相的制备与研究（英文）

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色谱 2017年第11期35卷 1120-1128页

作者： Elahe NAGHDI Kourosh TABAR HEYDAR Ali SHARIFI Seyyed Hamid AHMADI Chemistry and Chemical Engineering Research Center of Iran

A new ionic liquid-based high-performance liquid chromatography Stationary phase is reported.A derivative of N-methyl pyrrolidinium tetrafluoroborate was covalently immobilized on the surface of silica particles to prepare silica-based N-methyl pyrrolidinium tetrafluoroborate(SilprMP BF4)Stationary phase.The obtained ionic liquid-modified silica was evaluated and confirmed by elemental analysis,infrared spectroscopy,and thermogravimetric analysis.A column was packed with the modified particles.The retention behavior of aromatic compounds,alkyl benzenes,and acidic and basic compounds on the SilprMP BF4 Stationary phase was studied under reversed-phase liquid chromatography conditions.The effect of the eluent pH on the separation of the acidic and basic compounds was also studied.The new Stationary phase involves multiple retention mechanisms,such as electrostatic,hydrophobic,ion-dipole,and anion-exchange interactions,which might lead to multipurpose separation media.

关键词： reversed-phase high-performance liquid chromatography Stationary phase ionic liquids (ILs) pyrrolidinium

Directional derivative-based method for quasi-Stationary voltage support analysis of single-infeed VSC-HVDC units

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High Voltage 2020年第5期5卷 511-522页

作者： Arcadio Perilla Jose Luis Rueda Torres Elyas Rakhshani Roni Irnawan Filipe Faria da Silva Mart van der Meijden Claus Leth Bak Alex Alefragkis Anna Lindefelt Electrical Sustainable Energy Department Delft University of TechnologyMekelweg 42628 CDDelftThe Netherlands 2Department of Energy TechnologyAalborg UniversityPontoppidanstraede 1119220AalborgDenmark 3TenneT TSO B.VArnhemThe Netherlands 4EnerginetFredericiaDenmark

This study presents an investigation of the impact of the quasi-Stationary voltage support provided by a voltage source converter(VSC)connected to a single point of a power system.Based on the directional derivative concept,an analytical method is developed to quantify the sensitivities of the AC bus voltage with respect to the VSC reactive power control modes.Based on a real case study,it is shown that the method applies to VSC units that are part of VSC-HVDC systems,which can operate in a point-to-point or multi-terminal configuration.Time-domain simulations are performed to verify the findings from the application of the analytical method on a reduced size power system.

关键词： Stationary method system.

A reversed phase/hydrophilic interaction/ion exchange mixed-mode Stationary phase for liquid chromatography

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Chinese Chemical Letters 2019年第2期30卷 470-472页

作者： Sainan Zhang Feifang Zhang Bingcheng Yang Xinmiao Liang Shanghai Key Laboratory of New Drug Design School of Pharmacy East China University of Science and Technology

A reversed phase (RP)/hydrophilic interaction (HILIC)/ion exchange (IEX) mixed tri-mode Stationary phase (TMSP) has been prepared via a divergent synthesis scheme starting from propylamine on silica then by amine-epoxy reactions with 1,4-butanedioldiglycidyl ether and tertiary amines (N,Ndimethyldecylamine, DMDA). Its retention mechanism was found to follow RP/HILIC/IEX mixed-mode.The stop-flow test revealed that TMSP had good compatibility with 100% aqueous mobile phase. It demonstrated effective separation towards several kinds of compounds or drug molecules and their counterions within a single run.

关键词： Mixed-mode Stationary phase Reversed phase liquid chromatography Hydrophilic interaction liquid chromatography Ion exchange Drug molecules

SINGULARITY-FREE NUMERICAL SCHEME FOR THE Stationary WIGNER EQUATION

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Journal of Computational Mathematics 2019年第2期37卷 170-183页

作者： Tiao Lu Zhangpeng Sun School of Mathematical Sciences. Peking University Beijing 100871 China School of Mathematical Sciences Peking University Beijinc 100871 China

For the Stationary Wigner equation with inflow boundary conditions, the numerical convergence with respect to the velocity mesh size are deteriorated due to the singularity at velocity zero. In this paper, using the fact that the solution of the Stationary Wigner equation is subject to an integral constraint, we prove that the Wigner equation can be written into a form with a bounded operator B[V]. which is equivalent to the operatorA[V]=θ[V]/v in the original Wigner equation under some conditions. Then the discrete operators discretizing B[V] are proved to be uniformly bounded with respect to the mesh size. Basted on the thcoretical findings, a singularity-free numerical incthod is proposed. Numerical results are provided to show our improved numerical scheme performs much better in numerical convergence than the original scheme based on discretizing A[V].

关键词： Stationary Wigner equation Singularity-free Numerical convergence

Preparation of polar group derivative β-cyclodextrin bonded hydride silica chiral Stationary phases and their chromatography separation performances

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Chinese Chemical Letters 2019年第3期30卷 643-649页

作者： Baojing Zhao Lan Li Yuting Wang Zhiming Zhou School of Chemistry and Chemical Engineering Beijing Institute of Technology State Key Laboratory of Explosion Science & Technology Beijing Institute of Technology

Three novel β-cyclodextrin compounds derived with piperidine which is flexible, L-proline containing a chiral center, ionic liquid with 3,5-diamino-1,2,4-triazole as the cation were designed and synthesized as chiral selectors for enantiomer separation, whose name were(mono-6-deoxy-6-(piperidine)-β-cyclodextrin, mo no-6-deoxy-6-( L-p ro li ne)-β-cyclodextri n, mono-6-deoxy-6-(3,5-diamino-1,2,4-triazole)-β-cyclodextrin, multi-substituted 3,5-diamino-1,2,4-triazole-(p-toluenesulfonic)-β-cyclodextrin),respectively. In addition, to enhance the polarity of chiral Stationary phases, hydrosilylation and silylation reactions were implemented to derive ordinary silica, the common used selector carrier, to hydride silica, whose surface is covered with proton. 31 pyrrolidine compounds and some chiral drugs were tested in both polar organic mobile phase mode and normal mobile phase mode. 6-Deoxy-6-Lproline-β-cyclodextrin-CSP showed satisfactory separations in polar organic mobile phase mode and exihibited a strong separation capability in different pH values; multi-substituted 3,5-diamino-1,2,4-triazole-(p-toluenesulfonic)-β-cyclodextrin-CSP can separate pyrrolidine compounds in both mobile phase modes with high resolutions and separation efficiency compared to commercially available CSPs,making it to be the most valuable object to study. The composition of mobile phase, type of Stationary phase as well as the peak problem of chromatograms was discussed deeply.

关键词： β-Cyclodextrin Polar group Hydride silica Stationary phase Separation performance

The Stationary distribution and extinction of a double thresholds HTLV-I infection model with nonlinear CTL immune response disturbed by white noise

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International Journal of Biomathematics 2019年第5期12卷 221-240页

作者： Kai Qi Daqing Jiang Tasawar Hayat Ahmed Alsaedi College of Science China University of Petroleum (East China) Qingdao 266580P.R.China Key Laboratory of Unconventional Oil and Gas Development China University of Petroleum (East China) Ministry of Education Qingdao 266580P.R.China Nonlinear Analysis and Applied Mathematics (NAAM)-Research Group King Abdulaziz University JeddahSaudi Arabia Department of Mathematicsf Quaid-i-Azam University 45320 Islamabad 44000 Pakistan

This paper investigates the stochastic HTLV-I infection model with CTL immune response,and the corresponding deterministic model has two basic reproduction numbers.We consider the nonlinear CTL immune response for the interaction between the virus and the CTL immune cells.Firstly,for the theoretical needs of system dynamical behavior,we prove that the stochastic model solution is positive and global.In atldition,we obtain the existence of ergodic Stationary distribution by stochastic Lyapunov functions.Meanwhile,sufficient condition for the extinction of the stochastic system is acquired.Reasonably,the dynamical behavior of deterministic model is included in our result of stochastic model when the white noise disappears.

关键词： HTLV-I infection CTL immune response CD4+ T cells Stationary distriution extinction

Porous graphene decorated silica as a new Stationary phase for separation of sulfanilamide compounds in hydrophilic interaction chromatography

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Chinese Chemical Letters 2019年第4期30卷 863-866页

作者： Lijun Song Haijuan Zhang Tianpei Cai Jia Chen Zhan Li Ming Guan Hongdeng Qiu Laboratory on Pollution Monitoring and Control College of Chemistry and Chemical Engineering Xinjiang Normal University CAS Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province Lanzhou Institute of Chemical Physics Chinese Academy of Sciences

Porous graphene(PG) has potential applications in numerous fields because of the existence of nanopores in the plane. In this study, porous graphene decorated silica microspheres(Sil-PG) were successfully fabricated by assembling PG onto the silica particles surface in deep eutectic solvents(DESs).Experimental results demonstrate that this new Stationary phase can facilitate the separation of six sulfonamides compounds in hydrophilic chromatographic conditions. The successful synthesis of the SilPG Stationary phase provides a basis for the application of porous graphene-modified materials as the Stationary phase for liquid chromatography, and offers the possibility to broaden the application of PG in the field of chromatography.

关键词： Porous graphene Hydrophilic interaction chromatography Stationary phase Sulfonamides Human serum samples

Stationary distribution and periodic solution of stochastic chemostat models with single-species growth on two nutrients

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International Journal of Biomathematics 2019年第6期12卷 23-41页

作者： Miaomiao Gao Daqing Jiang Taxawar Haya College of Science China University o/Petroleum(Haul China)Qingdao 266580P.R.China Keg laboratory of Unconventional Oil and Cos Development China University of Petroleum(East China)Ministry of Education.Qingdao 260580.P.It.China Nonlinear Analysis and Applied Mathematics(NAAM)-Research Group Department of Mathematics.King Abdulaziz University Jeddah 21589 Saudi Arabia Department of Mathematics Quaid-I-Azam University 45320 Islamabad 44000.Pakistan

In this paper,we consider two chemostat models w th random perturbation,in which single species depends on two perfectly substitutable resources for growth.For the autonomous system,we first prove that the solution of the system is positive and global.Then we establish sufficient conditions for the existence of an ergodic Stationary distribu tion by constructing appropriate Lyapunov functions-For the non-autonomous system,by using Mas'minskii theory on periodic Markov processes,we derive it admits a nontriv ial positive periodic solution.Finally,numerical simulations are carried out to illustrate our main results.

关键词： Chemostat model Lyapunov function Stationary distribution Markov pro cess periodic solution.