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Universal Concentration Scaling on Rheometric Properties of Polydisperse and High Molecular Weight Polyacrylamide Aqueous Solutions

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Chinese Journal of Polymer Science 2022年第11期40卷 1432-1440页

作者： yuan-qi Fan Alfredo Lanzaro Xue-Feng yuan Institute for Systems Rheology Guangzhou UniversityHigher Education Mega-CenterGuangzhou510006China

A great progress has been made over the last decades in studying concentration scaling on rheometric properties of monodisperse polymer ***,the effects of polydisperse polymer solutions on such a concentration scaling remain *** this work,rheometric properties of industrially relevant polydisperse and high molecular weight polyacrylamide(PAAm)aqueous solution have been *** results show a concentration scaling of the characteristic relaxation time,the plateau modulus and the zero-shear viscosity across a concentration range from 10c^(*)to 250c^(*).The time-concentration superposition principle is validated and extended in the data analysis of the terminal dynamic *** concentration scaling exponent of their shifting factors is significantly smaller than the results of monodisperse polymer solutions in good andθsolvents reported in the *** steady shear viscosity and shear stress of 18M PAAm aqueous solutions with relatively lower concentration(≤35c^(*))could also be superimposed into a master curve with the shear-thinning exponent of 0.73±0.03 and0.27±0.03,respectively,over a wide range of shear rates in about six orders of ***,for 18M PAAm aqueous solutions with higher concentration(≥48c^(*))in an intermediate shear thinning regime,the scaling exponent shows a pronounced concentration *** shear thinning exponent of steady shear viscosity varies from 0.73 to 0.57 as concentration is increased,and then increases from 0.57 to 0.90from sufficiently high shear *** increasing shear rate,the shear-thinning exponent of 18M PAAm aqueous solutions at all concentrations converges to the lower bounded value observed in the relatively less concentrated(≤35c^(*))18M PAAm aqueous solutions,i.e.,0.73±0.02 for shear viscosity and 0.27±0.02 for steady shear stress,*** reveals that the concentration effects of polydisperse polymer solutions could be greatly reduced by the dynamic"molecular indi

关键词： Polymer solution Polydispersity Rheometric properties Time-concentration superposition principle

General variational solution for seismic and static active earth pressure on rigid walls considering soil tensile strength cut-off

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第5期24卷 432-449页

作者： Shiguo XIAO yuan qi Pan XIA Key Laboratory of High-Speed Railway Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 60031China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Department of Geological Engineering Southwest Jiaotong UniversityChengdu 610031China

According to the limit equilibrium state of soils behind rigid walls and the pseudo-static approach,a general closed-form solution to seismic and static active earth pressure on the walls,which considers shear and tension failure of the retained soil,is put forward using a variational calculus *** application point of the active resultant force specified in the proposed method is explained with a clear physical meaning related to possible movement modes of the *** respect of the derived nine dependent equations reflecting the functional characteristics of the earth pressure,the proposed method can be performed easily via an implicit *** are 13 basic factors related to the retained soils,walls,and external loads to be involved in the proposed *** tension crack segment of the slip surface is obviously influenced by these parameters,apart from vertical seismic coefficient and geometric bounds of the surcharge,but the shear slip segment maintains an approximately planar shape almost uninfluenced by these ***,the proposed method quantitatively reflects that the resultant of the active earth pressure is always within a limited range under different possible movements of the same wall.

关键词： Active earth pressure Tensile strength cut-off Variational calculus method Pseudo-static method Strip surcharge

Development of component stiffness equations for thread-fixed one-side bolt connections to an enclosed rectangular hollow section column under tension

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 568-586页

作者： Fu-Wei WU yuan-qi LI Department of Structural Engineering Tongji UniversityShanghai 200092China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China

The derivation and validation of analytical equations for predicting the tensile initial stiffness of threadfixed one-side bolts(TOBs),connected to enclosed rectangular hollow section(RHS)columns,is presented in this *** unknown stiffness components are considered:the TOBs connection and the enclosed RHS ***,the trapezoidal thread of TOB,as an equivalent cantilevered beam subjected to uniformly distributed loads,is analyzed to determine the associated *** on the findings,the thread-shank serial-parallel stiffness model of TOB connection is *** analysis of the tensile stiffness of the enclosed RHS face due to two bolt forces,the four sidewalls are treated as rotation constraints,thus reducing the problem to a two-dimensional plate *** to the load superposition method,the deflection of the face plate is resolved into three components under various boundary and load *** to the plate deflection theory of Timoshenko,the analytical solutions for the three deflections are derived in terms of the variables of bolt spacing,RHS thickness,height to width ratio,***,the validity of the above stiffness equations is verified by a series of finite element(FE)models of T-stub *** proposed component stiffness equations are an effective supplement to the component-based method.

关键词： initial stiffness component based method thread-fixed one-side bolt rectangular hollow sections analytical equation

Empirical mode decomposition using variable filtering with time scale calibrating

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Journal of Systems Engineering and Electronics 2008年第6期19卷 1076-1081页

作者： yuan Ye Mei Wenbo Wu Siliang yuan qi School of Information Science and Technology Beijing Inst. of Technology Beijing 100081 P. R. China School of Industrial Design and Information Engineering Beijing Inst. of Clothing Technology Beijing 100029 P. R. China The Science and Technology Committee of China Aerospace Science and Industry Corporation Beijing 100854 P. R. China

A novel and efficient method for decomposing a signal into a set of intrinsic mode functions （IMFs） and a trend is proposed. Unlike the original empirical mode decomposition （EMD）, which uses spline fits to extract variations from the signal by separating the local mean from the fluctuations in the decomposing process, this new method being proposed takes advantage of the theory of variable finite impulse response （FIR） filtering where filter coefficients and breakpoint frequencies can be adjusted to track any peak-to-peak time scale changes. The IMFs are results of a multiple variable frequency response FIR filtering when signals pass through the filters. Numerical examples validate that in contrast with the original EMD, the proposed method can fine-tune the frequency resolution and suppress the aliasing effectively.

关键词： empirical mode decomposition variable FIR filtering time scale calibrating.

Velocity measurement technique for high-speed targets based on digital fine spectral line tracking

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Journal of Systems Engineering and Electronics 2006年第1期17卷 6-12页

作者： Wen Shuliang yuan qi Dept. of Electronic Engineering Beijing Inst. of Technology Beijing 100081 P. R. China No.23 Inst. of the Second Research Academy China Aercspace Science and Industry Corporation Beijing 100854 P. R. Caina

Target vdocity and acceleration are two of the most important features for identification of warheads and decoys in ballistic missile defense phased array radar systems. Velocity compensation is also the necessary step for one-dimensional range profile imaging. According to the high-vdocity characteristics of ballistic objects and the low data rate of phased array radars with multiple target tracking, a fine spectral line digital velocity tracking frame is presented and a new method is developed to extract velocity error and resolve the velocity ambiguity in the measurement loop. Simulation results demonstrate the effectiveness of the proposed technique.

关键词： radar tracking radial velocity measurement velocity error extraction velocity ambiguity

Conductive polypyrrole incorporated nanocellulose/MoS_(2)film for preparing flexible supercapacitor electrodes

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Frontiers of Materials Science 2021年第2期15卷 227-240页

作者： qi yuan Ming-Cuo MA Research Center of Biomass Clean Utilization Beijing Key Laboratory of Lignocellulosic ChemistryCollege of Materials Science and TechnologyBeijing Forestry UniversityBeijing 100083China

Conductive films have emerged as appealing electrode materials in flexible supercapacitors owing to their conductivity and mechanical ***,the unsatisfactory electrode structure induced poor output performance and undesirable cycling stability limited their ***,a well-designed film was manufactured by the vacuum filtration and in-situ polymerization method from cellulose nanofibrils(CNFs),molybdenum disulfide(MoS_(2)),and *** electrode presented an outstanding mechanical strength(21.3 MPa)and electrical conductivity(9.70 S cm^(-1)).Meanwhile,the introduce of hydrophilic CNFs induced a desirable increase in diffusion path of electrons and ions,along with the synergistic effect among the three components,further endowed the electrode with excellent specific capacitance(0.734 F·cm^(-2))and good cycling stability(84.50%after 2000 charge/discharge cycles).More importantly,the flexible all-solid-state symmetric supercapacitor delivered a high specific capacitance(1.39 F·cm^(-2)at 1 mA·cm^(-2))and a volumetric energy density(6.36 mW·h·cm^(-3)at the power density of 16.35 mW cm^(-3)).This work provided a method for preparing composite films with desired mechanical and electrochemical performance,which can broaden the high-value applications of nanocellulose.

关键词： cellulose nanofibril molybdenum disulfide polypyrrole flexible supercapacitor

About 300 days Optical Quasi-periodic Oscillations in the Long-term Light Curves of the Blazar PKS 2155-304

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Research in Astronomy and Astrophysics 2022年第8期22卷 284-293页

作者： qi Zheng Xue-Guang Zhang qi-Rong yuan School of Physics and Technology Nanjing Normal UniversityNanjing 210023China

Based on the long-term light curves collected from the Catalina Sky Survey(CSS)(from 2005 to 2013)and the All-Sky Automated Survey for Supernovae(ASAS-SN)(from 2014 to 2018),optical quasi-periodic oscillations(QPOs)about 300 days can be well determined in the well-known blazar PKS 2155-304 through four different methods:the generalized Lomb-Scargle periodogram(GLSP)method,the weighted wavelet Z-transform technique,the epoch-folded method and the redfit *** GLSP determined significance level for the periodicity is higher than 99.9999%based on a false alarm *** redfit provided confidence level for the periodicity is higher than 99%in the ASAS-SN light curve,after considering the effects of red *** on continuous autoregressive process created artificial light curves,the probability of detecting fake QPOs is lower than 0.8%.The determined optical periodicity of 300 days from the CSS and ASAS-SN light curves is well consistent with the reported optical periodicity in the ***,three possible models are discussed to explain the optical QPOs in PKS 2155-304:the relativistic frame-dragging effect,the binary black hole model and the jet precession model.

关键词： (galaxies:)BL Lacertae objects:individual(PKS 2155-304) galaxies:active (galaxies:)quasars:supermassive black holes

THEORETICAL AND EXPERIMENTAL STUDY OF THE WAVE FORCES ACTING ON THE BASE WITHOUT GAP IN SHALLOW SEA

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Journal of Hydrodynamics 1991年第2期3卷 75-80页

作者： Xie, Nan qi, Xin-yuan China Ship Scientific Research Cent Wuz China

Wave forces acting on the offshore structure are of importance for the structure design point of view. There is a so called 'Two Tension Leg Buoy Mooring System' designed to open up the oil field in South China Sea. Two bases of the system are sitting on the sea floor of 30 - 40 meters depth of water. In order to confirm the safety of this system, wave forces are investigated experimentally and numerically. Nowadays, the measured materials on this subject are scarce. In the model test of Dr. Chakrabarti, the test set-up necessitated a small uniform gap between the model and tank floor, and the correct results must be come from an adjustment. The authors have solved the problem. In the paper, two numerical methods are adopted: 3-D boundary integral equation method; eigen-function expression and matching method. The former consists of distribution of Haskind Green' function on the body surface. The latter, however, by dividing the whole fluid domain into subregions, the velocity potential for each subregions can be determined uniquely by matching the velocity potential on their common boundaries, which was expressed formally by its eigen function expansion. As an example, experimental and numerical results were given for a circular base in shallow sea. They agree quite well. Although both methods are effective, the matching method has more efficiency.

关键词： Hydrodynamics Fluid Structure Interaction Mathematical Techniques Boundary Element Method Ocean Engineering Structures Water Waves

MOTION OF TRACER PARTICLES IN A CENTRIFUGAL PUMP AND ITS TRACKING CHARACTERISTICS

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Journal of Hydrodynamics 2012年第5期24卷 785-793页

作者： LI Ya-lin yuan Shou-qi TANG Yue yuan Jian-ping Research Center of Fluid Machinery Engineering and Technology Jiangsu University Zhenjiang 212013 China

The Basset-Boussinesq-Oseen （BBO） equation can be used for most flows to trace the motion of a particle, but in a centrifugal pump, among the forces that act on the particles, one should also include those due to the impeller rotation, as additional effects. This paper firstly reviews various approximations of the BBO equation for the motion of dispersion particles in a viscous fluid. Then based on the motion equation for particles in low Reynolds number centrifugal pumps, a formula for calculating the tracking characteristics of tracer particles is deduced through the Fourier integral transformation. After that the deviations of the particle motion from the fluid motion, as predicted by the various approximations, are discussed and compared. At last, with an emphasis on the Particle Image Velocimetry （PIV） results, the tracking characteristics of particles are estimated. Also, advantages and disadvantages of different tracer particles are discussed and suitable tracer particles for application in PIV studies for flow fields in centrifugal pumps are suggested.

关键词： tracer particles equations of motion tracking characteristics centrifugal pump Particle Image Velocimetry (PIV)