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Effect of Crystallization and Entropy Contribution Upon the Mechanical Response of Polymer Nano-fibers:A Steered Molecular Dynamics Study

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Chinese Journal of Polymer Science 2023年第3期41卷 465-474,I0011页

作者： Rui Ma Dan Xu Chuan-fu luo Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters College of Physical Science and TechnologyYili Normal UniversityYining 835000China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China School of Applied Chemistry and EngineeringHefei 230026China

The mechanical response of polyethylene nano-fibers with the same chain length but different chain numbers are studied by using steered molecular dynamics *** shrinking or stretching forces acted on the chain ends are investigated according to the chain-end distance and temperature under isothermal or continuous warming-cooling conditions,*** inflection point is found in the ForceDistance response when temperature is below 500 *** inflection point is related to the balance between entropy force and inter-monomer interaction and it reflects the strong effect of crystallization on the mechanical response of the *** force at inflection point is also affected by the buckling effect due to increased stiffness when crystallization *** two stages found in the Force-Temperature response and the difference between the shrinking and stretching forces indicate the hysteresis of crystallization and *** forces at different shrinking and stretching rates reveal the entropy contribution upon the mechanical response,indicated by the Ramachandran plot of *** chain-conformation entropy is majorly contributed by dihedrals and is quantified by the information entropy of dihedrals,which has a highly similarity to the mechanical Force-Temperature *** enlarged forces in multiple chains over a single chain are attributed to the enhanced dihedral-conformation *** study provides a new insight to the dynamically mechanical response of polymer nano-fibers according to the effect of crystallization and entropy contribution.

关键词： Polymer fibers Crystallization Entropy contribution Mechanical response

Mars orbit insertion via ballistic capture and aerobraking

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Astrodynamics 2021年第2期5卷 167-181页

作者： Zong-fu luo Francesco Topputo School of Astronomy and Space Science Nanjing UniversityNanjing210023China School of Systems Science and Engineering Sun Yat-sen UniversityGuangzhou510006China Department of Aerospace Science and Technology Politecnico di MilanoMilano20156Italy

A novel Mars orbit insertion strategy that combines ballistic capture and aerobraking is *** ballistic capture orbits that neglect the aerodynamics are first generated,and are distilled from properly computed stable and unstable sets by using a pre-established method.A small periapsis maneuver is implemented at the first close encounter to better submit a post-capture orbit to the aerobraking *** adhoc patching point marks the transition from ballistic capture to aerobraking,from which an exponential model simulating the Martian atmosphere and a box-wing satellite configuration are considered.A series of apoapsis trim maneuvers are then computed by targeting a prescribed pericenter dynamic *** aerobraking duration is then estimated using a simplified two-body *** angle tuning cancels the inclination deflections owing to out-of-plane perturbation from the Sun.A philosophy combining in-plane and out-of-plane dynamics is proposed to simultaneously achieve the required semi-major axis and *** simulations indicate that the developed method is more efficient in terms of the fuel consumption,insertion safety,and flexibility when compared with other state-of-the-art insertion strategies.

关键词： ballistic capture aerobraking Mars orbit insertion

Shape Accuracy and Residual Stress Distribution of Nano-molded Semicrystalline Polymer:A Simulation Study

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Chinese Journal of Polymer Science 2022年第6期40卷 642-650页

作者： Dan Xu Yu-Yuan Lu Chuan-fu luo State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China School of Applied Chemistry and EngineeringHefei 230026China

The shape accuracy and residual stress distribution of a nano-molded semicrystalline polymer are studied by molecular dynamics *** polyethylene flakes are obtained by continuous cooling inside templates with four *** find that the curvature of contour curve near template corners decreases with corner angle.A simple 2D shape model of minimum surface energy is proposed to understand the shapes for repulsive and attractive *** confinement of template induces highly ordered chain packing in surface *** to the spacial distribution of local stress,we find the contracting stress caused by volume shrinkage during cooling concentrates on the chains perpendicular to the direction of relative stress *** distribution of von Mises stress indicates the outer layer of semicrystalline polymer flake has lower *** results provide a theoretical insight for better nano-molding techniques.

关键词： Polymer semi-crystallization Molecular dynamics simulation Template

Convergence of the Cesaro Mean for Rational Orthonormal Bases

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Acta Mathematica Sinica,English Series 2009年第4期25卷 581-592页

作者： Ying Xiong fu luo Qing LI Key Laboratory of Applied Mathematics Hubei ProvinceFaculty of Mathematics and Computer Science Hubei UniversityWuhan 430062 P. R. China

This paper deals with the convergence of the Cesaro mean for the rational orthonormal bases. Provided the set of zeroes of rational orthonormal bases is formed by a periodic repetition of the same finite sequence, the explicit expression of so-called block-Fejer kernel is available, and some properties of the block-Fejer kernel are discussed. Based on the convergence of the block-Cesaro mean, the convergence of Cesaro mean is also provided.

关键词： Cesaro mean trigonometric series rational orthonormal basis

Method of analyzing vibration characteristics of armature system of hermetically sealed electromagnetic relay

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第3期8卷 434-438页

作者： REN Wan-bin CUI Li luo fu-biao ZHAI Guo-fu School of Electrical Engineering and Automation Harbin Institute qf Technology Harbin 150001 China Guilin Aerospace Electronics Company Guilin 541002 China

Published research is minimal on vibration characteristics of hermetically sealed electromagnetic relay (EMR) ex- posed to mechanical environment. The vibration characteristics of armature system, link contact system with electromagnetic system will cause EMR malfunction. The nonlinear dynamics model of armature systems was studied by considering electro- magnetic attraction force and opposite mechanical force in this paper. Angular displacements of armature under different sinu- soidal vibration conditions are solved in order to obtain the failure mode result from armature system. Vibration tests showed the presented analyzing method is suitable for EMR. The conclusions are instructive for increasing vibration resistance of armature systems of EMR, and are significant for reliability design of switch apparatus.

关键词： Hermetically sealed electromagnetic relay (EMR) Armature system Vibration characteristics Analyzing method

Experimental Study of Entropy Production in Cells under Alternating Electric Field

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Chinese Physics Letters 2012年第8期29卷 284-287页

作者： DING Chang-Jiang luo Liao-fu Laboratory of Theoretical Biophysics School of Physical Science and TechnologyInner Mongolia UniversityHohhot 010021 College of Science Inner Mongolia University of TechnologyHohhot 010051

We put forward a new method for measuring the entropy production in the living *** involves heating the sample by alternating the electric field and recording the outward heat *** entropy production in a normal cell MCF10A and a cancerous cell MDA-MB-231 were measured and *** results show that the method is effective for the entropy measurement of a living *** scaled electro-induced entropy production rate(SEEP)of MDA-MB-231 monotonically increases with the electric field strength at 5–40 V/*** that of MCF10A changes non-monotonically and there exists a peak at 5–30 V/*** electro-induced entropy production ratio(EEPR)is smaller than 1 in a large range of field strengths,from 5 to 25 V/cm,which reveals that under 5–25 V/cm electric field exposure,the direction of the entropy flow may be changed from normal tissue to cancerous *** present a facile and effective strategy for experimentally investigating the thermodynamic properties of the cell and give a deeper insight into the physical difference between normal and cancerous cells under electric field exposure.

关键词： entropy Entropy recording

Blended skip entry guidance for low-lifting lunar return vehicles

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Acta Mechanica Sinica 2014年第6期30卷 973-982页

作者： Zong-fu luo Hong-Bo Zhang Guo-Jian Tang College of Aerospace Science and Engineering National University of Defense Technology

A skip entry guidance algorithm blending numerical predictor-corrector and nominal trajectory tracking is presented for lunar return *** guidance is decoupled into longitudinal and lateral channels.A piecewise bank-vs-energy magnitude profile and a sign profile are adopted in the skip phase.A magnitude parameter is used to adjust the predicted downrange,and a pseudo-crossrange at the beginning of the final phase is selected as the lateral control *** biases of both channels are nullified by a false position iteration *** on-line estimation and modeling method is introduced to compensate for aerodynamic and atmospheric uncertainties.A nominal trajectory for the final phase is generated based on actual reenter conditions,and the obtained nominal trajectory is tracked by a linear feedback law.A lateral corridor is used to manage the lateral *** proposed guidance algorithm is assessed using three-degree-of-freedom Monte Carlo analyses,and the results show a satisfactory and robust performance under highly stressful dispersions.

关键词： Skip entry guidance Numerical predictorcorrector Low-lifting vehicle Lunar return mission Bank profile

The research on the high quality TiO_2, MoO_3-doped WO_3 electrochromic film

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Chinese Chemical Letters 2007年第7期18卷 883-886页

作者： Wei luo Xiang Kai fu Li Hua Ma College of Chemistry and Chemical Engineering Southwest University Chongqing 400715 China

The high quality TiO2, MoO3-doped WO3 electrochromic film was prepared by the sol-gel method for the first *** sol, which has hydrogen peroxide （H2O2） and oxalic acid （H2C2O4）, was very stable at room temperature and quite suitable for the deposition of films. The WO3 electrochromic film prepared from this doped sol had excellent performance, such as short response time, no cracks, good adhesion to the substrate, high coloring efficiency and longevity of service.

关键词： TiO2 MoO3 WO3 Oxalic acid Sol-gel Electrochromic

Numerical Simulation of Tip Clearance Flow Passive Control in Axial Turbine

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Journal of Thermal Science 2008年第2期17卷 147-155页

作者： LI Wei QIAO Wei-yang XU Kai-fu luo Hua-ling College of Propulsion and EnergyNorthwestern Polytechnical University Xi＇an 710072 China

This paper focuses on the effects of five different passive turbine tip clearance flow control methods on the tip clearance flow physics, which consists of a partial suction side squealer tip, a double squealer tip, a pressure side tip shelf with inclined squealer tip on a double squealer tip, a tip platform extension edge in pressure side and in suction side respectively. A pressure-correction based, 3D Reynolds-averaged Navier-Stokes equations CFD code with Reynolds Stress Model was adopted. The variable specific heat was considered. The detailed tip clearance flow field with different squealer rims was described with the streamline and the velocity vector. Accordingly, the mechanisms of five passive controls were elucidated; the effects of the passive controls on turbine efficiency and tip clearance flow field were illuminated. The results showed that the secondary flow loss near the outer casing including the tip leakage losses and the passage vortex losses could be reduced in all the five passive control methods. The turbine efficiency could be increased via the rational passive turbine tip clearance flow control. The Improved PS Squealer had the best effect on turbine efficiency, and the efficiency increased by 0.215%.

关键词： contact face wave receiving tube absorber