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Investigation of Unsteady Aerodynamic Characteristics of a Seagull Wing in Level Flight

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Journal of Bionic Engineering 2009年第4期6卷 408-414页

作者： Cheolheui Han Department of Aeronautical & Mechanical Design Engineering Chungju National University72 Daehak-roChungju380-702Korea

Unsteady aerodynamic characteristics of a seagull wing in level flight are investigated using a boundary element method.A new no-penetration boundary condition is imposed on the surface of the wing by considering its *** geometry and kinematics of the seagull wing are reproduced using the functions and data in the previously published *** proposed method is validated by comparing the computed results with the published data in the *** unsteady aerodynamics characteristics of the seagull wing are investigated by changing flapping frequency and advance *** is found that the peak values of aerodynamic coefficients increase with the flapping *** thrust and drag generations are complicated functions of frequency and wing stroke *** lift is inversely proportional to the advance *** effects of several flapping modes on the lift and induced drag(or thrust)generation are also *** three single modes(flapping, folding and lead & lag),flapping generates the largest lift and can produce thrust *** three combined modes,both flapping/folding and flapping/lead & lag can produce lift and thrust larger than the flapping-alone mode *** is shown to increase thrust when combined with flapping,whereas lead & lag has an effect of increasing the lift when also combined with *** three modes are combined together,the bird can obtain the largest lift among the investigated *** though the proposed method is limited to the inviscid flow assumption,it is believed that this method can be used to the design of flapping micro aerial vehicle.

关键词： biomimetics aerial locomotion sea gull wing unsteady aerodynamics panel method

Normally Torsion-free Lexsegment Ideals

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Algebra Colloquium 2015年第1期22卷 23-34页

作者： Anda Olteanu Faculty of Mathematics and Computer Science Ovidius University Bd. Mamaia 124 900527 Constanta Romania

In this paper we characterize all the lexsegment ideals which are normally torsion-free. This will provide a large class of normally torsion-free monomial ideals which are not square-free. Our characterization is given in terms of the ends of the lexsegment. We also prove that, for lexsegment ideals, the property being normally torsion-free is equivalent to the property of the depth function being constant.

关键词： normally torsion-free ideal monomial ideals lexsegment ideals associatedprimes

Spin Transport in a Magnetic Superlattice with Broken Two-Fold Symmetry

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Chinese Physics Letters 2010年第6期27卷 167-170页

作者： HUO Qiu-Hong WANG Ru-Zhi CHEN Si-Ying XUE Kun YAN Hui Laboratory of Thin Film Materials College of Materials Science and Engineering Beijing University of Technology Beijing 100124 School of Optoelectronics Beijing Institute of Technology Beijing 100081 Australian Research Council Centre of Excellence for Quantum Computer Technology and School of Physics University of New South Wales Sydney New South Wales 2052 Australia

We theoretically investigate the spin-dependent electron transport properties in a magnetic superlattice （MSL） with broken two-fold symmetry. An abnormal barrier in the MSL can break the two-fold symmetry of the system when it is not located at the two-fold symmetry center. A two-fold symmetry breaking factor is introduced to describe the two-fold symmetry breaking degree. Our numerical calculations show that the transmission, the conductance and the spin polarization are non-trivially dependent on the two-fold symmetry breaking factor. When the factor is large enough, the polarization almost approaches 100% in a proper Fermi energy range. However, for two mutually mirror-symmetric MSLs with the same factor, their polarizations may be either similar or distinct. These features provide some clues to the design and applications of MSL-based spin filters or spin-dependent tunneling electron devices.

关键词： Spinning Electronics Transport Polarity Optical properties

Phacoemulsification in eyes with corneal opacities after deep anterior lamellar keratoplasty

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International Journal of Ophthalmology(English edition) 2019年第8期12卷 1344-1347页

作者： Hui Lin Juan Zhang Guo-Zhen Niu Xin-Yu Huang Yu-Shan Zhang Chun-Yu Liu Chang-Yue Zheng Yan-Long Bi Department of Ophthalmology Tongji Hospital Affiliated with Tongji University School of Medicine

To evaluate the maneuverability and efficacy of phacoemulsification and intraocular lens(IOL) implantation in eyes with corneal opacities after deep anterior lamellar keratoplasty(DALK), twelve eyes of 12 patients with mild to moderate corneal opacities after DALK and coexisting cataracts were analyzed retrospectively. Phacoemulsification and IOL implantation assisted with anterior capsule staining, as well as non-invasive optical fiber illumination, were performed on all eyes. No intraoperative or postoperative complications were noted. Mean corrected distance visual acuity(logMAR) improved from 1.24±0.17 to 0.73±0.22. Post-phaco intraocular pressure was maintained between 13 to 20 mm Hg in all cases throughout the follow-up period. Mean endothelial cell density decreased from 2258.42±205.94 to 1906.25±174.23 cells/mm2. Phacoemulsification and IOL implantation are safe and valid in eyes with mild to moderate corneal opacities after DALK and coexisting cataracts when assisted with anterior capsule staining and non-invasive optical fiber illumination.

关键词： phacoemulsification corneal opacity deep anterior lamellar keratoplasty staining illumination

A progressive route for tailoring electrical transport in MoS2

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Nano Research 2016年第2期9卷 380-391页

作者： Muhammad Arslan Shehzad1 Sajjad Hussain Muhammad Farooq Khan Jonghwa Eom Jongwan Jung Yongho Seo Graphene Research Institute Sejong University Seoul 143-747 Republic of Korea Faculty of Nanotechnology & Advanced Materials Engineering and Graphene Research Institute Sejong University Seoul 143-74 7Republic of Korea Department of Physics and Graphene Research Institute Sejong University Seoul 143-747 Republic of Korea

Typically, molybdenum disulfide （MoS2） synthesized by chemical vapor deposition （CVD） is polycrystalline; as a result, the scattering of charge carriers at grain boundaries can lead to performances lower than those observed in exfoliated single-crystal MoS2. Until now, the electrical properties of grain boundaries have been indirectly studied without accurate knowledge of their location. Here, we present a technique to measure the electrical behavior of individual grain boundaries in CVD-grown MoS2, imaged with the help of aligned liquid crystals. Unexpectedly, the electrical conductance decreased by three orders of magnitude for the grain boundaries with the lowest on/off ratio. Our study provides a useful technique to fabricate devices on a single-crystal area, using optimized growth conditions and device geometry. The photoresponse, studied within a MoS2 single grain, showed that the device responsivity was comparable with that of the exfoliated MoS2-based photodetectors.

关键词： MoS2 grain boundary liquid crystal electrical properties photoresponse

Bell inequality,separability and entanglement distillation

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Chinese Science Bulletin 2011年第10期56卷 945-954页

作者： LIMing FEI ShaoMing LI-JOST XianQing College of Mathematics and Computational Science China University of Petroleum Dongying 257061 China School of Mathematical Sciences Capital Normal University Beijing 100048 China Max-Planck-lnstitute for Mathematics in the Sciences Leipzig 04103 Germany Department of Mathematics Hainan Normal University Haikou 571158 China

In this review,we introduce well-known Bell inequalities,the relations between the Bell inequality and quantum separability,and the entanglement distillation of quantum *** is shown that any pure entangled quantum state violates one of Bell-like ***,quantum states that violate any one of these Bell-like inequalities are shown to be *** Bell inequalities that detect more entangled mixed states are also introduced.

关键词：贝尔不等式可分性纠缠蒸馏量子态混合态

A metric normalization of tree edit distance

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Frontiers of Computer Science 2011年第1期5卷 119-125页

作者： Yujian Li (1) liyujian@*** Zhang Chenguang (12) Beijing Univ Technol Coll Comp Sci & Technol Beijing 100124 Peoples R China Hainan Univ Coll Informat Sci & Technol Haikou 570228 Peoples R China

Traditional normalized tree edit distances do not satisfy the triangle inequality. We present a metric normalization method for tree edit distance, which results in a new normalized tree edit distance fulfilling the triangle inequality, under the condition that the weight function is a metric over the set of elementary edit operations with all costs of insertions/deletions having the same weight. We prove that the new distance, in the range [0, 1], is a genuine metric as a simple function of the sizes of two ordered labeled trees and the tree edit distance between them, which can be directly computed through tree edit distance with the same complexity. Based on an efficient algorithm to represent digits as ordered labeled trees, we show that the normalized tree edit metric can provide slightly better results than other existing methods in handwritten digit recognition experiments using the approximating and eliminating search algorithm （AESA） algorithm.

关键词： metric normalization tree edit distance,triangle inequality approximating and eliminating searchalgorithm (AESA)

Layered alkali titanates(A_(2)Ti_(n)O_(2n+1)):possible uses for energy/environment issues

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Frontiers in Energy 2021年第3期15卷 631-655页

作者： Taya(Ko)SAOTHAYANUN Thipwipa(Tip)SIRINAKORN Makoto OGAWA School of Energy Science and Engineering Vidyasirimedhi Institute of Science and Technology(VISTEC)WangchanRayong 21210Thailand School of Molecular Science and Engineering Vidyasirimedhi Institute of Science and Technology(VISTEC)WangchanRayong 21210Thailand

Uses of layered alkali titanates(A_(2)Ti_(n)O_(2n+1);Na_(2)Ti_(3)O_(7),K_(2)Ti_(4)O_(9),and Cs_(2)Ti_(5)O_(11))for energy and environmental issues are *** alkali titanates of various structural types and compositions are regarded as a class of nanostructured materials based on titanium oxide *** compared with commonly known titanium dioxides(anatase and rutile),materials design based on layered alkali titanates is quite versatile due to the unique structure(nanosheet)and morphological characters(anisotropic particle shape).Recent development of various synthetic methods(solid-state reaction,flux method,and hydrothermal reaction)for controlling the particle shape and size of layered alkali titanates are *** ion exchange ability of layered alkali titanate is used for the collection of metal ions from water as well as a way of their *** possible materials design made layered alkali titanates promising for energy(including catalysis,photocatalysts,and battery)and environmental(metal ion concentration from aqueous environments)applications.

关键词： layered alkali titanates photocatalysis hydrogen evdution metal ions collection

Synthesis of carbon nanofibers by ethanol catalytic combustion technique

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Journal of Central South University of Technology 2008年第1期15卷 15-19页

作者：李飞邹小平程进张红丹任鹏飞王茂发朱光 Research Center for Sensor Technology Beijing Information Technology Institute

A general, simple and economic synthetic method for synthesizing carbon nanofibers was presented. In the method, ethanol was employed as carbon source; metal salts such as nickel nitrate, ferric nitrate and ferric chloride were used as catalyst precursor respectively; copper plate was employed as the support material. A lot of products were obtained by catalytic combustion deposition of ethanol vapor. Then the as-prepared carbon nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersion X-ray spectroscopy and selected-area electron diffractometry. By analyzing the results of characterization, the conclusions are as follows: 1) the large catalyst particles tend to form large-diameter CNFs, small catalyst particles are inclinable to form small-diameter CNFs; 2) the morphology of the catalyst can affect the final morphology of the CNFs. Moreover, the possible growth mechanisms were proposed and the degree of graphitization of samples was estimated by Raman spectroscopy characterization.

关键词： synthesis ethanol catalytic combustion carbon nanofibers growth mechanism degree of graphitization