i*****l
发帖数: 50 | 1 那为什么sinW是martingale?
d sinW = cosW dW -1/2 sinW dt
drift term也不是0阿 |
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i*****l
发帖数: 50 | 2 前几天还有人问这个sinw的问题,有人说由symmetry就可以得到sinw是martingale |
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w**********y
发帖数: 1691 | 3
不是我说的吧?你再看看几天俺发的贴..
万能判断法则就是,ito lemma的drift是0.
martingale的定义是什么?-conditional expectation of the increment is zero.
E(X_t-X_s|F_s)=0 或者 E(X_t|F_s)=X_s
sin(w_t)的expectation是什么?--0
sin(w_t)是martingale么?--不是.
为什么?--E(sinw_t)=0. 但是 E(sinw_t-sinw_s|F_s)=E[sin(Wt-Ws+Ws)-
sinWs|F_s]=sinWs*{E[cos(Wt-Ws))]-1}!=0.
或者说E(sinW_t|F_s)!=sinW_s |
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L*****e
发帖数: 169 | 4 according to your derivation, E(sinWs)=0,sinWs is a random variable too.
therefore sinW_s is a martiangle. |
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g***y
发帖数: 4784 | 5 Si Nanowires as Sensors: Choosing the Right Surface
Cedric R. Leão, Adalberto Fazzio, and Antônio J. R. da Silva*
Instituto de Física, Universidade de São Paulo, CP 66318, 05315-970 S&
#227;o Paulo, SP, Brazil
Abstract:
We show, using ab initio calculations based on density functional theory,
that for hydrogen-passivated Si nanowires (SiNWs), the relative contribution
of surface atoms to the band-edge states varies according to the way these
surface atoms are bonded to the core on |
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m*******r
发帖数: 481 | 6 CNT or SiNW based Nanoelectronics could be the biggest hype over the last
decade. If you are not in Harvard, MIT, and Bay Area (Stanford and Berkeley)
, and you are working in this field, it will be very difficult to land a
job in industry. I want to get out of this trap. Any one has any comment? |
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C********g
发帖数: 211 | 7 需要用到back scattered electron(BSE) modes of SEM来表征SiNW的core-shell
structure, p-core, i- and n- shells. 如果doping量很少， 比如Si:B or Si:P 大
约在1000:1，甚至更少，BSE work or not?
3Q! |
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