|
f**d
发帖数: 768 | 2 这是一本计算神经科学的优秀著作，全文拷贝这里（图和公式缺），有兴趣的同学可以
阅读
如需要，我可以分享PDF文件（－－仅供个人学习，无商业用途）
From Computer to Brain
William W. Lytton
From Computer to Brain
Foundations of Computational Neuroscience
Springer
William W. Lytton, M.D.
Associate Professor, State University of New York, Downstato, Brooklyn, NY
Visiting Associate Professor, University of Wisconsin, Madison
Visiting Associate Professor, Polytechnic University, Brooklyn, NY
Staff Neurologist., Kings County Hospital, Brooklyn, NY
In From Computer to Brain: ... 阅读全帖 |
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z********o
发帖数: 83 | 3 求思路，感谢哈
A binary tree is either an empty tree (represented by an empty pointer) or a
node consisting of a single integer value and two binary trees called the
left subtree and right subtree.
A binary tree T is given. A path in tree T is a non-empty sequence of nodes
of tree T such that each consecutive node in the sequence is a subtree of
its preceding node.
A path P in tree T is given. The amplitude of path P is the maximum
difference between values of nodes on path P. The amplitude of tree T i... 阅读全帖 |
|
a*******u
发帖数: 6324 | 4 嗐！轩哥，那不就是叫做Vibrato嘛。
就抖啊，就震啊，就一个词根啊。
http://en.wikipedia.org/wiki/Vibrato
http://zh.wikipedia.org/wiki/%E9%A1%AB%E9%9F%B3_(%E9%9F%B3%E6%A
颤音 (音乐)
维基百科，自由的百科全书
颤音是一种乐器技巧。
Vibrato
From Wikipedia, the free encyclopedia
Vibrato is a musical effect consisting of a regular, pulsating change of
pitch. It is used to add expression to vocal and instrumental music. Vibrato
is typically characterised in terms of two factors: the amount of pitch
variation ("extent of vibrato") and the speed with which the p... 阅读全帖 |
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D***0
发帖数: 138 | 5 网上投的，一开始是做online的两道题，一个是求树的Amplitude
In a binary tree T, a path P is a non-empty sequence of nodes of tree such
that, each consecutive node in the sequence is a subtree of its preceding
node. In the example tree, the sequences [9, 8, 2] and [5, 8, 12] are two
paths, while [12, 8, 2] is not. The amplitude of path P is the maximum
difference among values of nodes on path P. The amplitude of tree T is the
maximum amplitude of all paths in T. When the tree is empty, it contains no
path, and its ampl... 阅读全帖 |
|
s**g
发帖数: 66 | 6 Wien Bridge osc uses positive feedback to achieve frequency selection and
negative feedback to obtain start-up condition (overall loop gain >1).
There is a third feedback -- a thermal/PD/diode or FET clamping scheme - to
get amplitude control (negative feedback drops when oscillation amplitude
increases). But in the amplitude control loop, open loop gain (from
amplitude increase to variation of negative feedback gain) typically is not
very big. Therefore the suppression of amplitude fluctuation |
|
O*******d
发帖数: 20343 | 7 http://en.wikipedia.org/wiki/Decibel
When referring to measurements of amplitude it is usual to consider the
ratio of the squares of A1 (measured amplitude) and A0 (reference amplitude)
. This is because in most applications power is proportional to the square
of amplitude, and it is desirable for the two decibel formulations to give
the same result in such typical cases. Thus the following definition is used:
所以12分贝的增益是四倍的幅度增益，16倍的功率增益。 |
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s**m
发帖数: 340 | 8 错。我说的是PA AMPLITUDE.正常心律的CYCLE LENGTH你可以勉强说是AMPLITUDE，但是
根本没有
这个说法。我的PA AMPLITUDE就是指早搏的幅度，当然是指和正常心律的CYCLE LENGTH
比PA带来
的变化量。AMPLITUDE在数学上的定义就是变化的幅度。
rather |
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s**m
发帖数: 340 | 9 心律当然是周期性的，每一个activation之间的cycle length当然是oscillating,每
个activation之间的差异就是amplitude. 如果是一个premature activation, 这个
amplitude就特别大，所以我把这样的特殊的amplitude叫做PA amplitude.这些东西可
能对你们是不太了解，牛老板干心脏这么多年了，怎么可能不知道呢。她就是成心找麻
烦。 |
|
y*********m
发帖数: 33 | 10 大家给些思路吧，我能想出来的就只有用filter，但我不是统计背景的，所以真的不知道怎么用filter，大家谁能告诉一些用filter的细节，我将感激不尽，真的急啊。谢谢了
A data file contains time series energy consumption data for a home over a
one month duration sampled at 1 second granularity
Format - Each line contains a tuple , like
below:
1312182000,1322
1312182001,1322
1312182002,1328
...
The timezone is PDT and the energy readings are in Watts.
The Data:
This is aggregate energy consumption data for one home that contains the... 阅读全帖 |
|
y*********m
发帖数: 33 | 11 大家给些思路吧，如果能帮我回答，我将感激不尽，真的急啊。谢谢了
A data file contains time series energy consumption data for a home over a
one month duration sampled at 1 second granularity
Format - Each line contains a tuple , like
below:
1312182000,1322
1312182001,1322
1312182002,1328
...
The timezone is PDT and the energy readings are in Watts.
The Data:
This is aggregate energy consumption data for one home that contains the
following main appliances,
* Central AC 1 - The mo... 阅读全帖 |
|
j***h
发帖数: 4412 | 12 Earthquake detection systems can sound the alarm in the moments before a
big tremor strikes—time enough to save lives
Japan’s system, which went live in 2007, makes heavy use of personal
technology. Alerts go out not only on television and radio but through
special receivers in homes, offices and schools. Pop-up windows on
computers show a real-time map with the epicenter’s location and the
radiating seismic waves. A timer counts down to the shaking at your
location and highlights predicted inte... 阅读全帖 |
|
K**********n
发帖数: 1197 | 13
跟这帮自称理科的文科生物wsn实在纠缠不清楚。给丫们上点洋大人自己的说法吧，而
且都是学术圈的，已有reference一堆，其中一份是著名的兰德公司的报告。
另外，美国和澳洲已立法限制使用脑波扫描仪，拿脑波扫描仪扫本国公民已是联邦法的
重罪。不过这个比较难的是你无法证实谁接收了你的脑信号。所以立了法跟没立一个样。
Remote Mind Control Technology
Reprinted from SECRET AND SUPPRESSED: BANNED IDEAS AND HIDDEN
HISTORY, edited by Jim Keith, $12.95, available from
1-800-680-INET.
There had been an ongoing controversy over health effects of electromagnetic
fields (EMF) for years (e.g., extremely low frequency radiation and the
Navy's Project Sea... 阅读全帖 |
|
g********b
发帖数: 8461 | 14 这个我早就说过了，噪音并不能只看amplitude，frequency，tone都是重要因素。一个
嗡嗡响的机房和一个音乐室，哪里呆着舒服显而易见，虽然很明显音乐室里的声音
amplitude要比机房的大不少。
在汽车噪音里面，最低的高速也有大约60dB的噪音，在这个水平上差10dB的影响，远远
没有音色改善带来的影响大。表面上看Lexus车内噪音amplitude低，但是坐在Lexus里
面远没有坐在奔驰里面来的舒服，就是这个原因。 |
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D**********s
发帖数: 3139 | 15 音量控制对音质的影响，以前有一篇note写得不错，我找了半天才找到，其实还有用变
压器的方法，不过dac这块最保真的方法就是保持位深和标准输出电平，音量控制交给
前级和功放去管就好了，终究绕不过模拟放大这一关的。
Volume Control Technologies
Newsletter Edition:
July 2009 Issue
With the introduction of Benchmark’s HDR-VC™ (High Dynamic Range
Volume Control), many audio enthusiasts are taking another look at volume
control methods. What are the differences between the different volume
control topologies? Is one sonically superior, and why?
The important qualities to consider with respect to volum... 阅读全帖 |
|
j***h
发帖数: 4412 | 16 Earthquake detection systems can sound the alarm in the moments before a
big tremor strikes—time enough to save lives
Japan’s system, which went live in 2007, makes heavy use of personal
technology. Alerts go out not only on television and radio but through
special receivers in homes, offices and schools. Pop-up windows on
computers show a real-time map with the epicenter’s location and the
radiating seismic waves. A timer counts down to the shaking at your
location and highlights predicted inte... 阅读全帖 |
|
j***h
发帖数: 4412 | 17 Earthquake detection systems can sound the alarm in the moments before a
big tremor strikes—time enough to save lives
Japan’s system, which went live in 2007, makes heavy use of personal
technology. Alerts go out not only on television and radio but through
special receivers in homes, offices and schools. Pop-up windows on
computers show a real-time map with the epicenter’s location and the
radiating seismic waves. A timer counts down to the shaking at your
location and highlights predicted inte... 阅读全帖 |
|
z******n
发帖数: 8851 | 18 注：不是我写的，这是两年前我从别的网站上扒下来存的，分享给大伙，请不要转。。。
如何自制消音伴奏 by 东海
原唱MP3找不到的情况比较少，歌曲伴奏找不到却是常有的事情，尤其是一些通俗老歌
，要么没有伴奏，要么是以前VCD格式下粗糙的单声道伴奏，或者LD盘粗重的主旋律捣
乱。怎么办？自己试试消音。具体的消音原理这里不提了，大家GOOGLE一下就可以找到
，我只说我自己是如何制作消音伴奏的。前提，PC上安装了CE2.1（2.0）加上至少
Ultrafunk fx插件。BBE和WAVES我在消音时没有用到。
消音伴奏我常用的方法分两种，一种是CE自己带的，在Effects->Amplitude->Channel
Mixer,选vocal cut,通过调整New Left Channel和New Right Channel的百分比来控制
原声的保留程度。原唱制作得比较精良的，左右声道伴奏混音又不多的，可以用100%消
，否则伴奏损失惨重。那时需要消到大约90%处（具体要听出来的效果）。另一种是
DirectX->Untrafunk FX->Phase->Presets,Sontius：fx-... 阅读全帖 |
|
s*****o
发帖数: 787 | 19 任何数的实数次方好像可以得到：
任何复数先写为 C = Amplitude * exp(i*Phase+iK*2*pi), K=0,1,2,..., 幅度
Amplitude>0为实数，相位Phase为任意实数
则 C^m = abs(Amplitude^m) * exp[(i*Phase+iK*2*pi) * m],其中m为任意实数
但是如果m为复数，我就不会玩了。
又：在朱令案的讨论中，终于对我上升到人身攻击，这是迟早的事情。暴民终究是暴民
，即使有几个假惺惺作出君子的姿态。我还是站在神经病医院的围墙外看他们几个暴民
在里面狂欢吧。 |
|
t******n
发帖数: 2939 | 20 ☆─────────────────────────────────────☆
btphy (btphy) 于 (Sat May 25 03:19:10 2013, 美东) 提到:
版上弱智真多，这么简单的问题都搞不清楚。证明如下。
exp(2i pi e)=(exp(2i pi) )^e=1^e=1
==> 2i pi e=ln(1)=0
==> pi e=0
证毕。
★ 发自iPhone App: ChineseWeb 7.7
☆─────────────────────────────────────☆
feverpitch (狂热) 于 (Sat May 25 05:42:46 2013, 美东) 提到:
这个问题很难啊
☆─────────────────────────────────────☆
heathen (The real folk blues) 于 (Sat May 25 05:57:11 2013, 美东) 提到:
不难。刚才搞错了，LZ的公式“正确”。不过还可以更简单。
exp(2*i*pi)=1 ==> 2*i*pi=ln(1... 阅读全帖 |
|
s**m
发帖数: 340 | 21 我是研究心律不齐的，早搏(premature activation, or PA)导致心律周期（cycle
length）发生变化。我把变化的幅度叫做PA amplitude.其单位是ms.
牛老板点评： How can a change in cycle length be an AMPLITUDE? Doesn’t make
sense to measure amplitude in ms
牛老板是学物理出身。我需要研究一个系统的稳定性。系统当然有非线性，我提出先进行非线性建模，
然后对非线性模型进行分段线性化：piecewise linearization.老板追问我：What is this?
Why you can do this in this study?前前后后十几封email给她解释这个问题，到最后我给
她画出一条指数曲线然后逐点画切线准备跟她解释这个概念。牛老板大概咨询过她老公了，知道丢人
了，一谈到这个问题就说：of course, it is common sense.
我的研究中需要建模，用术语说就是system identification. Matlab专 |
|
s**m
发帖数: 340 | 22 here is a good explanation:
Amplitude is also the maximum value of the magnitude. The magnitude is
simply the absolute value of the displacement, and since the amplitude is
the maximum value of the displacement, the amplitude will be the maximum of
the magnitude.
If you took a tape measure and measured the distance between the equilibrium
point and the current position for a given time for a wave, that's the
magnitude.
If you took a tape measure and measured how far away the wave gets over all
t |
|
j***h
发帖数: 4412 | 23 Earthquake detection systems can sound the alarm in the moments before a
big tremor strikes—time enough to save lives
Japan’s system, which went live in 2007, makes heavy use of personal
technology. Alerts go out not only on television and radio but through
special receivers in homes, offices and schools. Pop-up windows on
computers show a real-time map with the epicenter’s location and the
radiating seismic waves. A timer counts down to the shaking at your
location and highlights predicted inte... 阅读全帖 |
|
K**********n
发帖数: 1197 | 24 学术界珍稀有限的原版外文资料，
Remote Mind Control Technology
Reprinted from SECRET AND SUPPRESSED: BANNED IDEAS AND HIDDEN
HISTORY, edited by Jim Keith, $12.95, available from
1-800-680-INET.
There had been an ongoing controversy over health effects of electromagnetic
fields (EMF) for years (e.g., extremely low frequency radiation and the
Navy's Project Seafarer; emissions of high power lines and video display
terminals; radar and other military and industrial sources of radio
frequencies and micr... 阅读全帖 |
|
发帖数: 1 | 25 讀讀這兩段吧，雖然不是個大家一致接受的結論、觀察時間也不夠久，但至少它對於氣
候暖化與渦漩南下的關係提供了一個理論。
A study in 2001 found that stratospheric circulation can have anomalous
effects on weather regimes.[29] In the same year researchers found a
statistical correlation between weak polar vortex and outbreaks of severe
cold in the Northern Hemisphere.[30][31] In more recent years scientists
identified interactions with Arctic sea ice decline, reduced snow cover,
evapotranspiration patterns, NAO anomalies or weather anomalies which are
linked... 阅读全帖 |
|
g********b
发帖数: 8461 | 26 人感觉安静与否并不是只看amplitude，还得看frequency和tone。你在计算机机房里听
那些嗡嗡声，虽然不大但是会很不爽，但是在音乐室里欣赏音乐，虽然声音很大但是心
情愉悦。这是很大的区别。
另一个好例子就是胆机和晶体管放大器的区别。数据上胆机和晶体管放大器出来的声音
没有什么区别，至少在amplitude, frequency和tone上都没区别，但是人就是觉得胆机
的听着比晶体管的舒服。 |
|
X***9
发帖数: 7385 | 27
不是我，而是本田
正如黑说的换换尾灯就好，不需要做任何其他改动
除了新的
Amplitude reactive dampers.
Using two separate damping systems, Amplitude Reactive Dampers provide
superior ride comfort and handling in virtually all driving conditions. One
damping system is tuned to provide maximum efficiency on smoother roads with
small inputs, and the other is tuned to handle large inputs such as rough
roads, potholes, and sudden steering and braking action. The result is that
the Accord Hybrid is engineered to remain composed and comfo... 阅读全帖 |
|
u***n
发帖数: 117 | 28 还是不太明白amplitude of tree的含义，例如：
1
/ \
2 3
/
4
从root 1 到leaf 3的长度是1，到leaf4的长度是2，那amplitude是2吗？
还是max-min = 2 - 1 = 1？
谢了~ |
|
m*********0
发帖数: 120 | 29 Update
两个coding：
1. Give array, return the number of possible arithmetic sequence (等差数列)。
{-1,1,3,3,3,2,1,0} return 5
2. Given a tree of N nodes, return the amplitude of the tree。Amplitude 就是
从root到leaf， Max-Min的差~找所有路径，返回最大值
coding实在codility上面做的~~~
Reasoning和GMAT很像。有简单数学，和推理~~~
Reasoning：
1~5填表格，空了五个数，推理数是啥。
有一类就是给出假设，statement，结论，问充分必要性。
还有一类就是给statement，然后问上面的statement支持下面哪种情况。
刚收到amazon online assessment的邀请，看到有三种题型，啊啊啊，表示23都木有见
过听说过啊。有人遇到过么？马上就要test了，求助啊~另外弱问下，一般code test是
三道题，90min么？
1) ... 阅读全帖 |
|
u***n
发帖数: 117 | 30 还是不太明白amplitude of tree的含义，例如：
1
/ \
2 3
/
4
从root 1 到leaf 3的长度是1，到leaf4的长度是2，那amplitude是2吗？
还是max-min = 2 - 1 = 1？
谢了~ |
|
c*******o
发帖数: 27734 | 31 ☆─────────────────────────────────────☆
Phase (amplitude) 于 (Tue Feb 9 18:49:55 2010, 美东) 提到:
国内竞争环境非常恶劣
主要靠关系
空气很差
地铁很挤
开车的都没有公德
房价很高，物价飞涨
整个中国经济都面临崩盘的危险
我现在真后悔回国发展了
☆─────────────────────────────────────☆
tauruse (戒) 于 (Tue Feb 9 18:51:00 2010, 美东) 提到:
回去之前就应该有人告诉过你这些了吧
至于中国经济崩盘，我倒是没啥担心的
☆─────────────────────────────────────☆
repeating (random) 于 (Tue Feb 9 18:52:35 2010, 美东) 提到:
可是看见我哥们在国内飞黄腾达，不服气啊。
☆─────────────────────────────────────☆
Phase (amplitude) 于 (Tue Feb |
|
y***u
发帖数: 5243 | 32 1 richter magnitude差10倍，是用log10来做衡量的
The Richter magnitude scale, also known as the local magnitude (ML) scale,
assigns a single number to quantify the amount of seismic energy released by
an earthquake. It is a base-10 logarithmic scale obtained by calculating
the logarithm of the combined horizontal amplitude of the largest
displacement from zero on a Wood–Anderson torsion seismometer output. So,
for example, an earthquake that measures 5.0 on the Richter scale has a
shaking amplitude 10 tim |
|
p***o
发帖数: 30 | 33 Here is your dynamic warm up... its long, but with what you need, I believe
this is the best way to go and im sure you will learn it quick with a lot of
repitition!
-forward and lateral leg swings x10 each
-forward to back arm swings, hammers (behind the head arm swings), arm
swings leaning over x10each
-behind the back arm stretch (10 sec), reach toes (10sec)
-walk out and back push ups into updog stretch x10
-hip rotations (6 each direction)
-alternate push ups to side plank x10
-glute/ham b... 阅读全帖 |
|
k****e
发帖数: 647 | 34 谢谢GannTrader(甘哥?)，karma，cadenzasong，Hower，知心哥，xiaobingzai的祝福!
为了节省版面资源，俺就不一一回复啦；拿到offer一定发包子，奔奔歌；现在版面好
热闹。
@Hower: 我后期是用Cool Edit做的，都是同样的流程（人懒）：
1)Effects->Delay Effects->Delay(choose rich room)
2)Effects->Delay Effects->Echo(Choose '50s Sheen!)
3)Effects->Delay Effects->Full Reverb(Choose Medium Concert Hall_Warm)
4)Effects->Amplitude->Hard Limiting(Limit Max Amplitude to -1.5db，boost参数
就根据需要来设置了)--PS:这里可以选中一部分做hard limiting, 不同的地方可能
boost的程度不同，最后调节到伴奏和跟唱的音量协调了就可以了。个人小小的一点想
法，大家多交流~
@知心哥，过奖啦，那是... 阅读全帖 |
|
H***r
发帖数: 3303 | 35 哈哈，话筒和我用的一模一样，再次感觉这个话筒对于高音特别好。再讲一个我现在一
般用的后期，其实是参照上次康特给我说的配置，我感觉很不错，你试试看：
1)Effects->Delay Effects->Delay(choose rich room)
2)Effects->Delay Effects->Echo(Choose '50s Sheen!)
3)Effects->Delay Effects->Full Reverb(Choose Medium Concert Hall_Warm)
4)Effects->Amplitude->Hard Limiting(Limit Max Amplitude to -1.5db，boost参数 |
|
z******o
发帖数: 1224 | 36 调节音量的话，可以单轨模式下，选中一小节目标wave，
1) 用amplitude->amplify(整体增大或者减小音量)；
2）用amplitude->envelope（根据包络动态调节音量大小），可以用一些修改过的
preset，像修改smooth fade out；就像下面图里修改的，后半部分的音量减少到72%（
在每个节点上，右键出现edit point，可以修改幅度大小） |
|
b**********p
发帖数: 624 | 37 最近忙得四脚朝天，好不容易静下心来录歌，却发现问题多多，好沮丧啊。
啰嗦一堆问题，走过路过的同学请帮帮忙扫盲，最后麻烦听下我第一次录的歌给些建议
啊。
1， 最大的痛苦是：后期不会！
网上教程多又杂，我是看不懂也暂时没有时间学。只好到处乱找参数，可是效果不好，
这调音因声而异，按参数调很难成功啊。除非有高人根据我的声音指点？后期是最痛苦
最无助的。可惜身边没有高人相助啊。只能等有时间的时候再下功夫学习了。现在只能
-乱调！请大家看看图片：Reverb, Compressor,BBE 看看我哪些参数可以调整下。另外
，做了降噪; 还有Amplitude->normalize; Waves->C4->pop_vocal。
2，不知道设置是否有问题，录的歌声音巨小，后来网上找找才知道用了下面几种方法
调。
（1） BBE: 最右边旋钮
（2） Amplitude->Normalize
（3） 最后编辑完在多轨模式下"输出1"的左边拉那个V0一直拉到声音够大的地方（看
图我的声音是v16.2，伴奏是0）
我觉得我的设置肯定有问题，但是却不知道问题在哪里。以上3种方法我全用上才行。
对了，我用的... 阅读全帖 |
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b*****l
发帖数: 9499 | 38 我也是觉得，lz 能不能贴个使用过 PA amplitude 这个术语的 ref？还是这个术语是
lz 自己发明的？
我学的心电图的细节都忘光了。。。但是一般说到 oscillating 时，好像用 phase
shift 比较多，而 amplitude 貌似更多指振幅而不是指 temporal scale 上的差异。
。。
西可
找麻
选》 |
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s**m
发帖数: 340 | 39 Y轴：离散的ＲＲ间距，也就是cycle length，X轴是beat, 也就是说信号是离散的。然
后，窦性的时候基本稳定，有小的便宜，早搏的时候有个大的跳跃，这个跳跃的幅度在
上面的ｘｙ平面上画出来不就是amplitude么。magnitude指的是一个变量在某个时刻的
值，而amplitude是一段时间里面这个变量的最大幅度，也就是振幅。这个解释还是很
make sense的。 |
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s**m
发帖数: 340 | 40 这个概念还真没看到别人在研究。多数研究早搏信号的都是频率分析，我发现的是RR的
早搏幅度非常重
要。amplitude是指从平衡点的最大偏移量。如果把窦型的RR值看作平衡点，早搏导致
一个大的RR偏
移量,我把这个偏移量叫做PA amplitude,有什么问题么 |
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s**m
发帖数: 340 | 41 这个就牵强了吧，你的ｙ轴的phase shift of activation time我理解就是从
activation time为x轴的图上测出来的，对不对？然后把这个测出来的量作为从变量来
研究。所以，没有问题。然后，这个从变量的峰值谷值，你可以用amplitude,也可以用
其他专门的名称。我就不相信会有人用shift来描述y轴的偏移量。
我当然不是一定要用amplitude,但是这是个新概念，我用数学上尽可能准确的语言来描
述，为什么就这么难呢。 |
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s**m
发帖数: 340 | 42 magnitude, amplitude, shift这三个词的差别：
magnitude:从变量在某时刻的值，也就是y轴方向的
amplitude:变量的最大变化量，也就是幅度，也是y轴方向的
shift:自变量的便宜值，也就是在x轴方向的。
我彻底没有意识到对这些概念会有如此多的不同理解。 |
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s*********d
发帖数: 912 | 43 假如你现在做的是生物医学工程的研究的话, 你要用医生习惯的术语说话, 而不是你所
在的工程方向.
我在本科的时候就被告知对于正反馈和负反馈的定义, 控制方向的人和通信方向的人有
不同的理解. 对于角速度, 数学界的人和物理界的人有不同的称呼. 你说的这些
amplitude, magnitude, shift, 信号处理,控制,无线电, 数学,物理的等各个方向的人
的理解更是五花八门了.
比如magnitude, 我们现在指的是复变量的幅值, 对应于波动也就是正弦振动的有效值.
amplitude是指正弦振动的最大值, 你用来指一个随机变化的最大值我看着就有点儿别
扭, 不过我可以理解也许有的工程专业就是这样用的.
但是我们现在都是在为医生服务,为医疗界的人服务, 你就不能拿你的数学,物理, 无线
电,控制,信号处理的术语说话, 你要用医生听得懂的术语, 医疗界的术语,医学研究领
域通用的术语说话.在这方面,你不能用叫真为自己辩护, 而是要去虚心了解这一行的惯
例. |
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C***C
发帖数: 216 | 44 White noise is not necessarily Gaussian and Gaussian noise may not be white.
Whiteness means that the noise samples are not correlated and Gaussian means
that the amplitudes of the samples are Gaussian distributed. Hence, you can
have white non-Gaussian noise and non-white Gaussian noise.
Filtering a noise sequence introduce correlation into the sequence, but will
not alter the distribution of the amplitude due to the property of "linear
sum of Gaussians will be Gaussian". So, essentially, if yo |
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s**g
发帖数: 66 | 45 Wien-Bridge has decent distortion performance. But the amplitude control may
not be as good as you like to see.
DDS uses high speed DAC with built-in look-up table to generate waveform (
sine/triangular/square). The frequency accuracy is realized by internal
oscillator or PLL referenced to an external crystal; amplitude accuracy is
obtained by the DAC.
Add LPF or BPF to suppress distortion and noise (to meet 1mVrms spec). Add
buffer if you like to scale up swing or to drive considerable load or |
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g****t
发帖数: 31659 | 46 请问为啥Wien-Bridge类型的振幅控制会不好？
我觉得精度不够就是二极管工作区的曲线太陡或者太不陡，
把Wien-Bridge里的二极管接个可调电阻，
然后调一下说不定精度就上去了吧？
Wien-Bridge has decent distortion performance. But the amplitude control may
not be as good as you like to see.
DDS uses high speed DAC with built-in look-up table to generate waveform (
sine/triangular/square). The frequency accuracy is realized by internal
oscillator or PLL referenced to an external crystal; amplitude accuracy is
obtained by the DAC.
Add LPF or BPF to suppress distortion and noise |
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b*******2
发帖数: 2121 | 47 一般来说,The lowest amplitude that a healthy human ear can detect is 20mPa.
那么对于一个microphone 来说,怎么来看它能检测的最小的amplitude? specs 上哪个
参数是对应的? 怎样换算成 单位Pa 呢?
万分感谢! |
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l******y
发帖数: 204 | 48 能给个大概reasonable的范围么
我在RFID书上看到：Due to the weak coupling between the reader antenna and
the transponder antenna, the voltage fluctuations at the antenna of the
reader that represent the useful signal are smaller by orders of magnitude
than the output voltage of the reader.
In practice, for a 13.56MHz system, given an antenna voltage of
approximately 100V (voltage step-up by resonance) a useful signal of around
10mV can be expected.
这意思是说，reader antenna发出的信号amplitude在100伏，card用load modulation
使rea... 阅读全帖 |
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a*********3
发帖数: 660 | 49 定义 definition变量 variable面积 area直径 diameter半径 radius公式 formula
单价 unit price范围 range/scope/extent集合 set法则 principle本金 principal利
率 interest rate利息 interest单利 simple interest复利 compound interest正数
positive number负数 negative number解析式 analytic expression分类讨论
classified discussion性质 nature （不是很确定）奇函数 odd function偶函数
even function对称 symmetric坐标原点 origin单调性 monotonicity（不是很确定）
任意 random周期性 periodic 有界性 boundedness 数学 mathematics, maths(BrE)
, math(AmE) 公理 axiom 定理 theorem 计算 calculation 运算 operat... 阅读全帖 |
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q*****z
发帖数: 191 | 50 Thanks! I think I may have found them in the input file.
I was asked to simulate the mechanical wave propagation on a piece of soft
tissue. The amplitude of the motion on the surface is the main interest. So
I need to find both the amplitude of motion at each node and the coordinate
of those nodes.
Given the fact that I am still a learner in ABAQUS, this method may not be
the best. Any suggestions? |
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