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A computational study of the wing-wing and wing-body interactions of a model insect

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Acta Mechanica Sinica 2009年第4期25卷 421-431页

作者： xin yu Mao Sun Institute of Applied Physics and Computational Mathematics Beihang University 100191 Beijing China Institute of Fluid Mechanics Beihang University 100191 Beijing China

The aerodynamic interaction between the contralateral wings and between the body and wings of a model insect are studied, by using the method of numerically solving the Navier-Stokes equations over moving overset grids, under typical hovering and forward flight conditions. Both the interaction between the contralateral wings and the interaction between the body and wings are very weak, e.g. at hovering, changes in aerodynamic forces of a wing due to the present of the other wing are less than 3% and changes in aerodynamic forces of the wings due to presence of the body are less than 2%. The reason for this is as following. During each down- or up-stroke, a wing produces a vortex ring, which induces a relatively large jet-like flow inside the ring but very small flow outside the ring. The vortex rings of the left and right wings are on the two sides of the body. Thus one wing is outside vortex ring of the other wing and the body is outside the vortex rings of the left and right wings, resulting in the weak interactions.

关键词： Insect Aerodynamics Wing/winginteraction Wing/body interaction

Mapping the trends and prospects of battery cathode materials based on patent landscape

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Frontiers in Energy 2023年第6期17卷 822-832页

作者： Chen YANG xin-yu MU School of Japanese Culture and Economy Xi’an International Studies UniversityXi’an 710128China The Northeast Asian Research Center Xi’an International Studies UniversityXi’an 710128China

Advancing portable electronics and electric vehicles is heavily dependent on the cutting-edge lithium-ion (Li-ion) battery technology, which is closely linked to the properties of cathode materials. Identifying trends and prospects of cathode materials based on patent analysis is considered a kernel to optimize and refine battery related markets. In this paper, a patent analysis is performed on 6 popular cathode materials by comprehensively considering performance comparison, development trend, annual installed capacity, technology life cycle, and distribution among regions and patent assignees. In the technology life cycle, the cathode materials majorly used in electric vehicle have entered maturity stage, while the lithium cobalt oxide (LCO) cathode that is widely used in portable electronics is still in the growth stage. In global patent distributions, China holds more than 50% of total patents. In the top 10 patent assignees of 6 cathode materials, 2 institutes are from China with the rest being Japan (6) and Republic of Korea (2), indicating that the technology of cathode materials in China is relatively scattered while cathode research is highly concentrated in Japan and Republic of Korea. Moreover, the patent distribution has to consider practical issues as well as the impacts of core patents. For example, the high cost discourages the intention of applying international patents. This paper is expected to stimulate battery research, understand technical layout of various countries, and probably forecast innovative technology breakthroughs.

关键词： patent analysis cathode batteries technology life cycle

Reachability of Patterned Conditional Pushdown Systems

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Journal of Computer Science & Technology 2020年第6期35卷 1295-1311页

作者： xin Li Patrick Gardy yu-xin Deng Hiroyuki Seki Shanghai Key Laboratory of Trustworthy Computing East China Normal UniversityShanghai 200062China Graduate School of Informatics Nagoya UniversityNagoya 464-8601Japan

Conditional pushdown systems (CPDSs) extend pushdown systems by associating each transition rule with a regular language over the stack alphabet. The goal is to model program verification problems that need to examine the run-time call stack of programs. Examples include security property checking of programs with stack inspection, compatibility checking of HTML5 parser specifications, etc. Esparza et al. proved that the reachability problem of CPDSs is EXPTIME-complete, which prevents the existence of an algorithm tractable for all instances in general. Driven by the practical applications of CPDSs, we study the reachability of patterned CPDS (pCPDS) that is a practically important subclass of CPDS, in which each transition rule carries a regular expression obeying certain patterns. First, we present new satura-tion algorithms for solving state and configuration reachability of pCPDSs. The algorithms exhibit the exponential-time complexity in the size of atomic patterns in the worst case. Next, we show that the reachability of pCPDSs carrying sim-ple patterns is solvable in fixed-parameter polynomial time and space. This answers the question on whether there exist tractable reachability analysis algorithms of CPDSs tailored for those practical instances that admit efficient solutions such as stack inspection without exception handling. We have evaluated the proposed approach, and our experiments show that the pattern-driven algorithm steadily scales on pCPDSs with simple patterns.

关键词： conditional pushdown system pattern reachability saturation algorithm

Measurements of non-equilibrium and equilibrium temperature behind a strong shock wave in simulated martian atmosphere

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Acta Mechanica Sinica 2012年第5期28卷 1296-1302页

作者： xin Lin Xi-Long yu Fei Li Shao-Hua Zhang Jian-Guo xin xin-yu Zhang School of Optoelectronics Beijing Institute of Technology State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences

Non-equilibrium radiation measurements behind strong shock wave for simulated Martian atmosphere are presented in this paper. The shock wave is established in a hydrogen oxygen combustion driven shock tube. Time- resolved spectra of the Av = 0 sequence of the B^2∑^＋ → X^2∑^＋ electronic transition of CN have been observed through optical emission spectroscopy （OES）. A new method, which is based on fitting high resolution spectrum for rotational and vibrational temperatures measurement, is proposed to diag- nose temperature distribution behind the shock wave. It is estimated that the current scheme has the maximum deviation less than 8% （lσ） for vibrational temperature measurement through detailed analysis of the influence of the uncertainties of spectroscopic constants and spectral resolution. Radiation structure of the shock layer, including induction, relaxation and equilibrium process, and corresponding rotational and vibrational temperatures are obtained through time gating OES diagnostics with sub-microsecond temporal resolution. The present extensive results will strongly benefit the reaction rate estimation and computational fluid dynamics （CFD） code validation in high enthalpy Mars reentry chemistry.

关键词： Radiation measurements - Shock wave Marsre-entry Rotational temperature Vibrational temperature

Compatibilization of PBT/PP Blends by Adding Side-chain Liquid Crystalline Ionomer with Quaternary Pyridinium Groups

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Chemical Research in Chinese Universities 2011年第1期27卷 140-144页

作者： XU xin-yu Department of Polymer Materials and Engineering School of Chemistry and Materials Science Liaoning Shihua University Fushun 113001 P R. China

A side-chain liquid crystalline ionomer（SLCI） was synthesized by grafting copolymerization of 4-（4-ethoxybenzoyloxy）-4＇-allyloxybiphenyl and N-allyl-pyridium bromide on polymethylhydrosiloxane. The SLCI was blended with polypropylene（PP） and polybutylene terephthalate（PBT） by melt mixing. The thermal behavior, liquid crystalline properties, morphological structure, and mechanical properties of the blends were investigated by differential scanning calorimetry（DSC）, polarizing optical microscopy（POM）, scanning electron microscopy（SEM）, and tensile measurement. When a proper amount of SLCI was added, fine configurations were formed in the PBT/PP/SLCI blend system, and the mechanical properties were improved due to improved adhesion at the interface. When excess SLCI was added, an inhomogeneous structure resulted, which caused the mechanical properties to deteriorate.

关键词： Poly(butylent terephthalate) Poly(propylene) Liquid crystalline ionomer Compatibilization

Superdeformed Bands of ^(150)Gd in the Interacting Boson Model

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Chinese Physics Letters 1998年第8期15卷 561-563页

作者： LIU yu-xin Department of Physics Peking UniversityBeijing 100871 Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080

The electric quadrupole transitionγ-ray energies and the dynamical moments of inertia of the five superdeformed(SD)bands of ^(150)Gd have been investigated with a four parameter approach inspired of the interacting boson *** calculated results agree with experimental data *** indicates that the four parameter approach is powerful in describing both the yrast SD band and the excited SD bands of even-even nucleus no matter whether the bands are built upon some extra single particle excitations.

关键词： bands excited excitation

Verifying Contextual Refinement with Ownership Transfer

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Journal of Computer Science & Technology 2021年第6期36卷 1342-1366页

作者： Zhao-Hui Li xin-yu Feng School of Computer Science and Technology University of Science and Technology of ChinaHefei 230026China Department of Computer Science and Technology Nanjing UniversityNanjing 210023China State Key Laboratory for Novel Software Technology Nanjing UniversityNanjing 210023China

Contextual refinement is a compositional approach to compositional verification of concurrent *** has been much work designing program logics to prove the contextual refinement between the object implementation and its abstract ***,these program logics for contextual refinement verification cannot support objects with resource ownership transfer,which is a common pattern in many concurrent objects,such as the memory management module in OS kernels,which transfers the allocated memory block between the object and *** this paper,we propose a new approach to give abstract and implementation independent specifications to concurrent objects with ownership *** also design a program logic to verify contextual refinement of concurrent objects *** abstract *** have successfully applied our logic to verifying an implementation of the memory management module,where the implementation is an appropriately simplified version of the original version from a real-world preemptive OS kernel.

关键词： contextual refinement program logic concurrent object ownership transfer verification

Penetration and lubrication evaluation of vegetable oil with nanographite particles for broaching process

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Friction 2021年第6期9卷 1406-1419页

作者： Ming XU xin yu Jing NI School of Mechanical Engineering Hangzhou Dianzi UniversityHangzhou 310018China

With increasing environmental concerns,the substitution of mineral oil-based cutting fluid has become an urgent *** vegetable soybean oil as base fluid,nanofluid cutting fluids(NFCFs)were prepared by adding different weight concentrations of nanographite particles(NGPs),and their penetration and lubrication performances were studied.A novel simulated tool-chip slit with micrometersized geometry was manufactured to evaluate and quantify the penetration rate of the NFCFs by image analysis ***,a large number of comparative experiments on the closed-type broaching machine were carried out to compare the performance of the proposed NFCFs and a commercial cutting fluid in terms of cutting force,workpiece surface roughness,and metal *** is found that there is an optimal NGP concentration in NFCF for practical cutting *** the concentration of NGP is 0.4 wt%,the broaching process lubrication exhibits an ideal mixed lubricate state,resulting in minimal friction resistance,and thus,both the cutting force and chip curling angle reach their corresponding best ***,the proposed NGP-based vegetable-oil cutting fluid exhibits excellent environmentfriendliness and low-cost consumption in the minimal quantity lubrication(MQL)method;this demonstrates its potential for replacing the traditional broaching cutting fluid.

关键词： cutting fluid vegetable oil nano-graphite particle penetration broaching

Algorithm Implementation for Distributed Convex Intersection Computation

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Journal of Systems Science & Complexity 2020年第1期33卷 15-25页

作者： WANG Bingchang yu xin PANG Dandan School of Control Science and Engineering Shandong UniversityJinan 250061China School of Information and Electrical Engineering Shandong Jianzhu UniversityJinan 250101China

Intersection computation of convex sets is a typical problem in distributed *** this paper,the algorithm implementation is investigated for distributed convex intersection computation *** a multi-agent network,each agent is associated with a convex *** objective is for all the agents to achieve an agreement within the intersection of the associated convex sets.A distributed"projected consensus algorithm"is employed,and the computation of the projection term is converted to a constrained optimization *** solution of the optimization problem is determined by Karush-Kuhn-Tucker(KKT)*** implementable algorithms based on the simplex method are introduced to solve the optimization *** numerical examples are given to illustrate the effectiveness of the algorithms.

关键词： Convex intersection computation feasible direction method Lemke algorithm projected consensus algorithm