C**R
发帖数: 1047 | 1 首先
Accurate quantum Monte Carlo （QMC) simulations for the energy of the HEG
have been performed for several intermediate values of the density, in turn
providing accurate values of the correlation energy density.[3]
Vosko-Wilk-Nusair (VWN) [4]
Perdew-Zunger (PZ81) [5]
Cole-Perdew (CP) [6]
Perdew-Wang (PW92) [7]
HEG就是homogeneous electron gas,现在绝大多数functional都是基于这个
approximation的，问题就是这个HEG approximation很难进一步有突破（因为qmc实在
是太慢了），所以你说的那个什么精确Eex，就是你不懂。
在问你个我知道答案问题，为什么QMC算Cuprates... 阅读全帖 |
|
s*******s
发帖数: 623 | 2 Job ID: GF2012A001
Posting Title: Research Scientist/Research Associate/Electrobiochemist
Brief Introduction of Gate Fuels Inc.:
“Imagination, Innovation, Implementation --- Enabled Technologies for a
Green Clean World”
Gate Fuels Inc. is a research start-up firm based in Blacksburg, VA, with
the goal of developing microbial and cell-free platform technologies that
enable low-cost production of biochemicals, biofuels and electricity. The
first platform is based on industrially-safe Bacillus subt... 阅读全帖 |
|
a****o
发帖数: 6612 | 3 #9
：local: 一个算符在坐标表象的表示可以写成Dirac delta函数
：r| A|r'> = A(r) \delta(r-r')
：这个定义来自Parr&Yang的书的(2.1.24)
：non-local:做不到这一点的。比如HF里面的交换算符
我的理解，locality 和 non-locality并不是判断是不是DFT 或 KS DFT的标准。LSDA
中的local spin (electron) density，是个假定。从根本上讲，DFT并不需要假定
local spin density, 具体的functional才可能需要。
#13
：potential：指Hamiltonian operator中的potential operator, v_xc:=δExc[p]/δ
p
：势能：Hamiltonian的本征值除去动能的部分。比如E_xc，需要对v_xc积分。
："OEP是potential不是势能"的意思是OEP指的是v_xc部分而不是E_xc部分。
这里是你自己给“势能”加了个定义，（准确的说，应该是势，没有能字，所以我也不
准确。但是我用括号来指出... 阅读全帖 |
|
s********n
发帖数: 235 | 4 Title: INVESTIGATION OF THE FERMI EDGE IN SODIUM TUNGSTEN BRONZES BY PHOTO-
ELECTRON SPECTROSCOPY
Author(s): EGDELL, RG; HILL, MD
Source: CHEMICAL PHYSICS LETTERS Volume: 85 Issue: 2 Pages: 140-144
DOI: 10.1016/0009-2614(82)80318-7 Published: 1982
http://www.sciencedirect.com/science/article/pii/00092614828031
Title: OPTICAL TRANSITION TO FERMI LEVEL IN NAXWO3
Author(s): GIULIANI, G; STELLA, A; GUSTINET.A
Source: PHYSICS LETTERS A Volume: A 38 Issue: 7 Pages: 515-& DOI: 10.
1016/0... 阅读全帖 |
|
P****b
发帖数: 114 | 5 li-ion 电池的Specific energy density 要大的多，当然会有各种各样的问题。
这公司的网站瞎写，Li-ion 电池的Specific energy density: 150 to 250 W·h/kg
（wiki上的数据） |
|
y***o
发帖数: 416 | 6 我来试试：
A) Identify the types of plastic resin based on the appearance and the
combustion characteristics of plastic materials, e.g. PP, PE, PVC, ABS, PET,
PS, PC, PMMA, PVB, etc.
B) Determine the grade and use of the identified type of plastic resin, such
as injection molding, extrusion, drawing, blow molding etc., and give
recommendations of target customers based on the material properties.
C) Develop an appropriate sorting strategy for mixed plastic resins
according to the density differences.... 阅读全帖 |
|
发帖数: 1 | 7 本人米帝UC千老，求审稿机会，做过的课题如下：
1. Density Function/Time-dependent Density Functional Calculations for
molecules and nanostructures
2. Nanoplasmonics and polaritonics, quantum/classical eletrodynamics
computational development
3. Thousand atom electronic structure calculation methods development
4. Nonequilibrium Green's function transport and optical properties in
nanojunctions
5. Nonequilibrium dynamics in strongly correlated system
请各位牛人赏脸 |
|
d*******r
发帖数: 3875 | 8 【 以下文字转载自 Military 讨论区 】
发信人: wayofflying (小破熊), 信区: Military
标 题: 南京大学重大发现 揭露了转基因惊人秘密
发信站: BBS 未名空间站 (Sun Oct 2 23:46:36 2011, 美东)
南京大学张辰宇教授重大发现 “剑指”转基因食物安全(图)
在九月出版的《细胞研究》(Cell research)的一篇研究中，南京大学张辰宇教授课题
组展示了一项非常令人惊奇的发现——植物的微小核糖核酸（microRNA）可以通过日常
食物摄 取的方式进入人体血液和组织器官。并且，一旦进入体内，它们将通过调控人
体内靶基因表达的方式影响人体的生理功能，进而发挥生物学作用。该研究证明植物微
小核糖核酸可能是食物中的“第七种营养成分”（其他六种分别是水、蛋白质、脂肪
酸、碳水化合物、维他命和稀有元素）。
南大教授张辰宇作《21世纪生物科学与生物经济》讲座
原文地址
Exogenous plant MIR168a specifically targets mammalian LDLRAP1: evidence of
cross-... 阅读全帖 |
|
C*S
发帖数: 1658 | 9 IMHO, use 0 for self weight multiplier. I think this multiplier is for slabs
and beam/columns/walls whose self weight can be automatically calcualted by
the software based on their density and volume. You did not define storage
density and volume, right? |
|
n*****e
发帖数: 17 | 10 谢谢！
我做一个网格里的线性插值
class Density里面定义了 _ilen, _jlen, _rg[][];
#include "math.h"
double Density::bilinearRg(double x, double y) {
int i, j;
double x1, x2, y1, y2;
j=static_cast(round(x*_jlen,0));
~~~~~~~~~~~~~~~~ 'round': identifier not found
if(j<0) j=0;
if(j>_jlen) j=_jlen;
i=static_cast(round(y*_ilen));
~~~~~~~~ 'round': identifier not found
if(i<0) i=0; if(i>_ilen) i=_ilen;
x1=(j-.5)/_jlen;
x2=x1+1./_jlen;
y1=(i-.5)/_i |
|
g******s
发帖数: 733 | 11 多谢了！按照你说的，写了几行程序，但是算出的电压都有无穷大和复数了。
由方程 V(x)^2 dy/dx=a x，得V(x)=sqrt(a x dx/dy) = sqrt(alpha.*2.*omega_r.^2.*I./N./dc_dalpha)。请问程序错误在什么地方？所有参数都取自原论文。
N=120;
omega_r=240*2*pi; %omega_r=240;
density=2330;
l=1e-3;
w=1e-3;
h=50e-6;
I=density*h*l*w^3/12;
alpha=[0 1 2 3 4 6 7].*pi./180; % 取自图6b
dc_dalpha=[-0.25 0.495 0.75 0.74 0.495 -0.505 -1].*1e-10; % 取自图6b
V=sqrt(alpha.*2.*omega_r.^2.*I./N./dc_dalpha); % 公式 (4)
谢了！ |
|
g******s
发帖数: 733 | 12 多谢了！我用公式V(x)=sqrt(a x dx/dy) = sqrt(alpha.*2.*omega_r.^2.*I./N./dc_dalpha)算出的电压和转角的关系，原文计算出的电压和转角的关系，都附在附件上。看横坐标，电压相差一个数量级。
N=120;
omega_r=240*2*pi; %omega_r=240;
density=2330;
l=1e-3;
w=1e-3;
h=50e-6;
I=density*h*l*w^3/12;
alpha_rad=[1 2 3 4].*pi./180; % 取自图6b
alpha_degree=[1 2 3 4]; % 取自图6b
dc_dalpha=[0.495 0.75 0.74 0.495].*1e-10; % 取自图6b
V=sqrt(alpha_rad.*2.*omega_r.^2.*I./N./dc_dalpha); % 公式 (4)
plot(V,alpha_degree)
还有什么可能的错误？原文作者不理我。
多谢了！ |
|
c******e
发帖数: 18 | 13 To consider MLE of a distribution, in the form of density,
there should have a parameter, so I think maybe u forgot to
include it. Is the density like this:
f(x,a)=e^(-(x-a))/[1+e^(-(x-a))]^2, it's the logistic
distribution.
For this distribution, consider L(x,a), which is
L(x,a)=f(x1,a)*f(x2,a)*...*f(xn,a) and take log both sides,
l(x,a)=log[f(x1,a)]+log[f(x2,a)]+...+log[f(xn,a)]
E{derivative of log[f(X,a)]}=Integral{ [derivative of
f(x,a)/f(x,a)]*f(x,a)dx
=Integral{ |
|
c******k
发帖数: 1140 | 14 You were saying if the density is higher, the higher states in the
conduction band would be occupied. That would result in a higher frequency
or a lower wavelength.
From my measurement, compared to the lasing spectrum between the middle
contact and the contact 3, the lasing wavelength from the contact 3 (1574nm)
is larger than that of the middle contact (1560nm) meanwhile the current
density of the contact 3 is higher than that of the middle contact. But this
is contrary to what you are talking |
|
s**g
发帖数: 66 | 15 Sensitivity is determined by system noise, i.e. noise spectrum density
integrated over noise bandwidth.
Oscilloscope is a broadband system,500MHz in your case; while spectrum
analyzer is a narrowband system, realized by mixer + high Q filter (BPF),
resolution bw (noise bandwidth) typically between 100Hz and 1MHz. Although
the two systems may have comparable noise spectrum density by design, the
rms noise you mentioned above could be significantly different due to the
noise bw.
This difference co |
|
L*****e
发帖数: 169 | 16 Power spectral density and four transform are different.
The autocorrelation of white noise is actually delta funtion.
Power spectral density is the fourier transform of the autocorrelation
function.
Get it?
not because of phase. you are comparing apples to oranges. |
|
p*****t
发帖数: 966 | 17 这么讲吧
LZ是1W带internal matching的PA,记住，是输出口已经匹配到50 Ohms的。 那么你在设
计输出端的传输线的时候，特征阻抗就是50 ohms.但是如果只是给出特征阻抗，那会有
无数种的设计，你可以设计成很细，也可以很粗。要是用CPW的话，也会有很多设计。
和介质的厚度，介电常数等都有关，当这些确定的时候，就可以考虑power density.
一般PCB的power density和金属层的厚度关系最大。如 100微米厚，7毫米宽的铜层可
以通过10安培的电流。
然后就是估算你的电流。LZ现在考虑的是1W的输出级上的电流，那个可能不是最重要的
。从你的片子来看的话，频率肯定在10G以内。假设是CLASS AB的PA，drain
efficiency是20%的话，那射频功率和耗散功率之和为5watts,假设是5V的drain
biasing, 那power supply上的电流大概在1A左右。RF输出级的RF电流会很小，就几百
个毫安，具体的，你可以用反射系数和电流的公式在MATLAB里plot一下，找出峰值电流
就可以。但是我觉得对于你的设计，完全没有必要 |
|
ET
发帖数: 10701 | 18 gate voltage noise density:
vn^2=kf/(w*l*cox*f)
drain current noise density (due to gate noise) =
in^2=vn^2*gm^2
gm^2=2*Id*un*cox*(W/L)
so in^2=kf*Id/(L^2*f)
为何我看到的公式是：
i^2/(delta f) = kf*Id/(L^2*cox*f)
谁能给解释解释？ |
|
ET
发帖数: 10701 | 19 不是。。你这corner frequency是怎么定义的？
fcorner 是flicker noise density = thermal noise density那点
的frequency ..
所以，理论计算上只能是一个点。 怎么会从10hz to 100khz?
you |
|
ET
发帖数: 10701 | 20 啥technology node?
现在的65nm 45nm flicker noise corner 上MHz也完全现实的。
input referred noise的唯一物理意义是可比性，无法可测。
都是通过测量output noise density, 折算回去。 在simulation中，
也不要设定noise souce, 因为transistor本身就是个noise source, 要measure的就是
ouput noise density..
complain
source |
|
ET
发帖数: 10701 | 21 你不是都说了吗?
output noise density/(intrinsic gain)
以你的setup的话，这个65nm的technology, gmR <10
所以input refered noise比output noise density曲线相似，小40db. |
|
c*******c
发帖数: 726 | 22 Ja, so when I answer something whose result may be ambiguous due to several
independent issues. I always say 'suppose blah blah' and confirm the
questioners' acceptance of my assumption, then I draw the provisional answer.
Basically, as you mentioned, since effective mass and doping density both
affect scattering effect, all my previous analysis should base on the
influential difference from doping density are comparable and can be ignored
. Otherwise we cannot get the answer through quality ana... 阅读全帖 |
|
c*******c
发帖数: 726 | 23 Ja, so when I answer something whose result may be ambiguous due to several
independent issues. I always say 'suppose blah blah' and confirm the
questioners' acceptance of my assumption, then I draw the provisional answer.
Basically, as you mentioned, since effective mass and doping density both
affect scattering effect, all my previous analysis should base on the
influential difference from doping density are comparable and can be ignored
. Otherwise we cannot get the answer through quality ana... 阅读全帖 |
|
g*********n
发帖数: 808 | 24 GaAs vs. Si from wikipedia
Comparison with silicon
GaAs advantages
Some electronic properties of gallium arsenide are superior to those of
silicon. It has a higher saturated electron velocity and higher electron
mobility, allowing gallium arsenide transistors to function at frequencies
in excess of 250 GHz. Unlike silicon junctions, GaAs devices are relatively
insensitive to heat owing to their wider bandgap. Also, GaAs devices tend to
have less noise than silicon devices, especially at high fre... 阅读全帖 |
|
p***e
发帖数: 472 | 25 Here is a data sheet of the super capacitors from nesscap, for reference,
http://www.nesscap.com/product/module.jsp
Largest module is 500 F, 16V, 6kg. So the footprint and weight of the 7500F
module depends on the cell and module voltage level. I think one challenge
is to maintain the balance if too many cells in one module.
I'm curious if they include any other types of storage, like battery, in the
system. Cap is good for high power density, but not for energy density.
★ 发自iPhone App: Chin... 阅读全帖 |
|
b**s
发帖数: 589 | 26 1。这句话好像有点问题
2。如果孔小的话，有可能porosity会减小，也不是好事
3。还要考虑机械强度的问题
其实scaffold应该归到cellular materials的范畴，有很多东西可以借鉴cellular
materials的已经发展很好的理论
relationship between surface area and blood vessel density应该很早就有人作了吧
。他的新颖之处是不是在于老鼠in vivo， 我见到的研究angiogenesis 大多都是在鸡蛋
上做
的
都有SEM
density
area
with |
|
b**s
发帖数: 589 | 27 Another distinguishing tool is based on the presence of single-mode or
bimodal molecular weight distributions. A block copolymer representing a
single chemical species should display essentially single-mode behavior. By
contrast, homopolymer blends are more likely to exhibit bimodal
characteristics. One of the better ways to investigate this phenomenon is
density gradient ultracentrifugation. Assuming the two components possess
different densities, a bimodal distribution will be detected in t |
|
c*******n
发帖数: 1648 | 28 You got almost everything. But how to define the reaction? Lithium ion do
coordinate with (EO)6. You are right, lithium polymer complex is used as
current transport medium instead of anode, cathode...That's why I called it
electrolyte.
Energy density is low, that's why people want to understand what's the
transporting mechanism in order to increase energy density later by
manupulating molecular level parameter, But maybe it's just a dream of
scientists:)
consider
electrolyte
processed
these
sto |
|
w********h
发帖数: 12367 | 29 hehe, you must be in polymer engineering.
our languages are quite different.
my understanding is this:
your crosslink density is my entanglement molecular weight Me,
the lower Me, the higher crosslink density.
when Me=M0 (monomer molecular weight), it is crosslinked (also called
thermoset). is that right?
PS Tg=100C Me=18000g/mol
PBD Tg=-100C Me=1543g/mol
PS is normally glass-like (or thermoplastic) at room temperature because of
its high Tg.
When you increase your temperature to 130 to 150C,
yo |
|
M*******n
发帖数: 508 | 30 来自主题: Macromolecules版 - 几个弱智问题 do you mean apparent density by bulk density?
for (1) and (3), I don't think so. At least, you have steric effects.
and that's why we have LDPE and HDPE, right? |
|
l***u
发帖数: 1 | 31 1. Fourier Inversion Theorem
Th: If \int_{-\inf}^{\inf} \abs(g_{X}(t))dt <\inf, then X is absolutely
continuous with density
f(x)=1/(2*pi) \int_{\-inf}^{\inf} exp(-itx) g(t)dt
2. The Ch. f. of Laplace distribution, which has density is 1/2*exp(-\abs(x)),
is
g(t)=1/(1+t^2)
This is easy to verify by standard calculation.
3. So, by Fourier Inversion Theorem,
1/2*exp(-\abs(x))=1/(2*pi) \int_{\-inf}^{\inf} exp(-itx)*1/(1+t^2) dt
=1/(2*pi) \int_{\-inf}^{\inf} exp(itx)*1/(1+t^2) dt
|
|
g********5
发帖数: 62 | 32 since you already give the parameters of the distribution, there is no such
thing as minimal sufficient statistics here, if have to say one, then any
constant is.
I guess you misunderstand the problem itself.
Say, if X1..Xn are iid with density f(x)=exp{ - |x-mu|/beta} /(2*beta)
(In general, this is the density for double expontential distribution)
Then the minimal sufficient stat is the order stat. |
|
|
h***i
发帖数: 3844 | 34 找本regression的书翻翻吧
最好再复习一下mathematic stat.
如果你的data 是(y,x),如果你x的density不知道，简单一点，去翻翻kernel density
estimator
dis |
|
s******h
发帖数: 539 | 35 E{ Y(n) } can also use the pdf of (Y1, ..., Yn), and Y(n) is a function of (
Y1, ..., Yn). It's the change of variable theorem that you can find in most
Real Analysis books that guarantees this.
It's like if Xi IID~ N(0,1), say T = X1^2 + X2^2 + ... + Xn^2
E(T) can be calculated by both the normal density and chi-sqaure density.
the |
|
p********y
发帖数: 111 | 36 在看一个作图形分析的论文,有几处没看懂
1,any scalar field can be distorted into any other scaler field
如何理解?
2,为了克服这个困难,论文中用了cut low-density region 方法:
Since the space now has holes in it-precisely because we cut then out and
threw them away-the topology of the remaining space is nontrivial and can be
studied.
我的理解:
For example, the equation x + 5y = 0 has the trivial solution (0, 0).
Nontrivial solutions include (5, –1) and (–2, 0.4). 我们扔掉的low-density
区域就是那些含有trivial solution (0, 0)的区域? 我对这个对应过程转不过弯.
谢谢 |
|
t**********m
发帖数: 205 | 37 来自主题: Mathematics版 - 伟哥之乐 The joy of viXra
https://telescoper.wordpress.com/2011/05/19/
Posted in The Universe and Stuff with tags arXiv, astronomy, Cosmology,
Physics, scientific publishing, viXra on May 19, 2011 by telescoper
From time to time on this blog I post rants about the state of scientific
publishing, open access, the importance of the arXiv for astronomy and
cosmology, and so on.
This morning, however, I discovered an “alternative” side to the whole
business of online science, a site by the name of viXra. Mos... 阅读全帖 |
|
B****n
发帖数: 11290 | 38 f(x)可以是一個cumulative distribution function 只有在正的地方有正的density
所以像gamma distribution, Weibull distribution這些probability density
function的
不定積分都是 |
|
L*m
发帖数: 235 | 39 统计了近十余年来中国大陆高校在四大刊物上的发文，有些是挂名的，但不管如何，还
是都统计了。全名单如下
Annals of Mathematics
A proof of Demailly’s strong openness conjecture
Qi'an Guan（关启安 北京大学） Xiangyu Zhou（周向宇 中科院）
A solution of an L2 extension problem with an optimal estimate and
applications
Qi'an Guan（关启安 北京大学） Xiangyu Zhou（周向宇 中科院）
Construction of Cauchy data of vacuum Einstein field equations evolving to
black holes
Junbin Li（黎俊彬 中山大学） Pin Yu（于品 清华大学）
Special test configuration and K-stability of Fano varieties
Chi Li(李驰 普林斯顿大学 现stony broo... 阅读全帖 |
|
x********i
发帖数: 905 | 40 http://iccm.mcm.ac.cn/dct/page/1
Plenary Lectures
Group 1
Wei Zhang: RTF and L-functions
Kai-Wen Lan: Cohomology of automorphic bundles
Xinyi Yuan: On Faltings heights of CM abelian varieties
Jing Yu: On Linear Independence of Logarithms
Xuhua He: Cocenter of Hecke algebras
Jiu-Kang Yu: A GAGA theorem for p-adic groups
Jianya Liu: Manin's conjecture for a class of singular cubic
hypersurfaces
Lei Fu: Rigidity of $ell$-adic Sheaves
Si Li: Open-closed topologica... 阅读全帖 |
|
N***r
发帖数: 2539 | 41 近似等于大气压+沿程压力损失
沿程压力损失 delta_P = f*L/D*density*v*v/2
f -> 摩擦系数
L -> 管道长度
D -> 管道直径
density -> 密度
v -> 流速
f = 64/R for laminar flow
f = ****（不记得了） for turbulent flow
自己查查，很容易的。 |
|
g******p
发帖数: 111 | 42 could you please help review/complete/edit my translation of my mom's PET/CT
report, in particular, on the chest part (attached in the 2nd post)? i
skipped many places that i cannot find the words.
i am bringing her in for a follow-up in the states. Really appreciated your
help!
PROCEDURE: (18F)-fluorodeoxyglucose was administered intravenously via the
right antecubital vein. To allow for distribution and uptake of radiotracer,
the patient was allowed to rest quietly for 60 minutes in a shielded... 阅读全帖 |
|
r**********7
发帖数: 243 | 43 不是我翻的，借花献佛，有错的大家指正，祝好运！
Noncontrast head CT (10/20/2013):
Findings:
The 4th ventricle is not well visualized. Suspicious high density in
the posterior cranial fossa. No obvious dilation or expansion of the
rest ventricles, cisterns or sulcus. No midline deviation. No obvious
cerebral density or morphology change. The bony calvarium is within
normal limits.
Contrast enhanced brain MRI (10/22/2030):
Sequence:T1W/T2W/DWI/FLAIR/MRA
Paramagnetic contrast agent, 0.2 ml/kg, IV bolus.
Findings:
Bilatera... 阅读全帖 |
|
l**x
发帖数: 110 | 44 知道这个版的专业医生很多，所以占宝地求指点。恳请大家一点给点指导，下一步怎么
办合适？
患者44岁，男，6年前因为肝癌做了肝移植 （符合米兰标准），之后无灾无病好几年。
去年2016年初发现轻微贫血，血色素12，因为当时在服小剂量阿司匹林，于是停服，看
看有没好转。托托拉拉到了年底，还是贫血，血色素10.5。医生说做个内镜。于是在胃
内发现一个肿瘤，内镜医生直觉是GIST。随后CT，但CT却没有异常。4月初第二次胃镜
，GIST依然还在，取样活检表明可能肝癌转移或者是非常罕见的HAC。第二次CT 报告大
小46x35mm，说比较第一次32mm变大了。可能第一次看片医生那天喝多了？肿瘤位置在
Fundus，非常接近GOJ。
AFP好久没有查了，因为肝上的情况一直很好，肝移植前AFP 100多，移植后AFP一直小
于2。上一次至少是2，3年前。也是疏忽了。现在AFP 254. 显然胃上这个要么是转移，
要么是HAC。
下周二医生还要安排一次PETCT，周三见外科医生，估计排除转移外就安排切除了。 求
这里的专家教授指点，这个情况如何是好？下面我贴上最近几个报告。
个人感觉肝移植后5，6年转... 阅读全帖 |
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l******u
发帖数: 2314 | 45 西北大学的Hersam博士做出来的东西让我有这样的印象，我偶尔翻过，不仔细。建议有
兴趣的仔细读读，别被我误导了。
Arnold MS, Green AA, Hulvat JF, et al.
Sorting carbon nanotubes by electronic structure using density
differentiation
NATURE NANOTECHNOLOGY 1 (1): 60-65 OCT 2006
Arnold MS, Stupp SI, Hersam MC
Enrichment of single-walled carbon nanotubes by diameter in density
gradients
NANO LETTERS 5 (4): 713-718 APR 2005
另外，杜邦的Ming Zheng的一些文章好像也让我有这样的印象，比如：
Zheng M, Jagota A, Semke ED, et al.
DNA-assisted dispersion and separation of carbon nanotubes
NA |
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m***c
发帖数: 1403 | 46 I dont quite understand what you write below. I thought energy density
is just decided by cathode, given the usual anodes are so light in
density comparing to cathodes.
Lithium
at |
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m***c
发帖数: 1403 | 47 these are just fancy concepts. what industry really needs and really cares
is
still hardcore batteries, high energy density, high power density,
volumetrically, gravimetrically. it is never ever changed. |
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x********g
发帖数: 595 | 48 电磁场里 △Φ= ρ ， charge density
引力场 也是同样的方程，△A= ρ , mass density
M = ∮ ρdx^3 = ∮ dx^3 △A
我是这么理解的。 |
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x******i
发帖数: 3022 | 49
Here's a standard procedure that works for all translation invariant
correlation functions.
1. Fourier transform correlation function to get spectral density.
[In your case, it is probably 8*pi*a^3/(1+a^2*k^2)^2]
2. Generate random data with delta-function correlation
3. Spatial Fourier Transform that data
4. Filter with Sqrt[spectral density]
5. Inverse Fourier Transform |
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a*******i
发帖数: 11664 | 50 I didn't read the paper very carefully but this is about measurements on
nanopariticles with diameters of 10-
12 nm, right?
when you read most textbooks, they say:
for direct bandgap: alfa ~ (hv-Eg)^0.5
for indirect bandgap: alfa ~ (hv-Eg+/-phonon)^2
those two equations are for 3D bulk materials! not for 2D Quantum Well or 1D
nanowire or QDs.
The relation between the absorption coefficient and the energy is mainly
determined by the density of states.
The density of states for 3D, 2D, 1D and QDs |
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