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硅基材料是新一代高容量锂离子蓄电池负极材料的典型代表,近年来已成为理论研究和应用研究的热点.本文介绍了锂离子电池硅基负极材料的制备方法、电化学性能及其研究现状,分析了硅材料作为锂离子电池负极材料存在的问题;讨论了硅材料作为锂离子电池负极材料的研究前景.并指出若能克服目前存在问题,将有望成为新一代锂离子电池负极材料. 相似文献
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Liondas CA; Chrissoulidis DP 《The Quarterly Journal of Mechanics and Applied Mathematics》2007,60(3):275-287
This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field. 相似文献
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Goodman TNT; Micchelli CA; Rodriguez G; Seatzu S 《IMA Journal of Numerical Analysis》1998,18(3):331-354
It is shown that, under certain conditions, orthonormalizingthe positive integer shifts of an exponentially decaying functionon the half line by the Gram-Schmidt process leads to a limitingprofile given by orthonormalizing all their integer shifts onthe whole line. These results derive from properties of Choleskyfactorization of bi-infinite and semi-infinite matrices. Anexample is provided by the negative exponential function andconjectures are given, supported by numerical evidence, forthe Gaussian and Lorentz function. 相似文献
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M. Raffel H. Richard K. Ehrenfried B. Van der Wall C. Burley P. Beaumier K. McAlister K. Pengel 《Experiments in fluids》2004,36(1):146-156
Three-component particle image velocimetry measurements at moderate speeds and observation distances can now be accomplished on a routine basis. This article discusses the experiment performed on a 4 m-diameter model rotor in the 6-m×8-m open test section of the Large Low Speed Facility of the German–Dutch Wind Tunnels. More than half a terabyte of raw data were recorded at various positions on the advancing and retreating sides of the rotor in order to obtain detailed measurements of the trailing vortex in the frame of an international project. This paper addresses measuring techniques and possible sources of errors and presents a limited number of cases for the purpose of illustrating the solutions to numerous technical challenges relating to the acquisition and analysis of vortical flows.List of symbols
C
T
thrust coefficient (T/2
R
4)
-
M
magnification
-
r
c
radius of vortex core (mm)
-
R
rotor radius (m)
-
T
thrust (N)
-
u,v,w
velocity components in x, y and z coordinates (m/s)
- (u,v,w)wt
velocity components in wind tunnel coordinates (m/s)
-
U
max
maximum in-plane velocity component (m/s)
-
W
max
maximum out-of-plane velocity component (m/s)
-
x,y,z
particle image velocimetry (PIV) frame coordinates (m)
- (x,y,z)wt
wind tunnel coordinates (m)
- t
time delay (s)
- Z
light sheet thickness (mm)
- Z
light sheet thickness (mm)
-
rotor rotation frequency (rad/s)
-
rotor azimuth angle during recording (deg) vortex age
-
rotor shaft angle (deg)
-
x
displacement measurement error
-
advance ratio (V/R)
-
air density (kg/m3)
-
circulation (m2/s)
-
z
vorticity (s–1)
Abbreviations AFDD
Aeroflightdynamics Directorate
- BVI
blade–vortex interaction
- DLR
Deutches zentrum für Luft- und Raumfahrt
- DNW
German–Dutch Wind tunnel
- HART
HHC aeroacoustic rotor test
- LLF
large low speed facility
- NASA
National Aeronautics and Space Administration
- ONERA
Office National dEtudes e de Recherches Aerospatiales
- RANS
Reynolds-averaged Navier–Stokes
- SPR
stereo pattern recognition
- 3C-PIV
three-component particle image velocimetry 相似文献
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从烟草(品种革新一号)单倍体花粉植株的叶和茎产生的愈伤组织,结合悬浮培养,获得的细胞分离出原生质体。在液体培养基中静置培养,12小时后原生质体开始变为卵圆形,细胞壁明显可见,24小时后完成第一次细胞分裂。以后继续分裂形成浅黄色的愈伤组织,在培养四星期后可达1毫米大小,再放到转床上进行旋转培养18天左右,愈伤组织可达3—4毫米大小。当转移到分化培养基后,分别分化出苗及根,长成完整的植株。 原生质体再生细胞的分裂与分化,不仅受不同器官来源的愈伤组织及其年龄的影响;还受分化培养基的基本成份及所用细胞分裂素的类型等的影响。 相似文献