2011年4月6日星期三

2011年4月4日星期一

新研發醫療用微流體裝置　用碳奈米管“抓”癌細胞

來自美國麻省理工學院(MIT)與哈佛大學醫學院(Harvard Medical School)的兩位教授，合作開發出一種僅有1美分硬幣大小的微流體(Microfluidic)裝置，其內部的探測器滿佈微小的碳奈米管，能從血液樣本數十億的健康細胞中辨別出個別癌細胞，還能偵測到尺寸只有40奈米的病毒。

2011年4月1日星期五

ORCAD PSPICE -Simulation

Orcad ActiveParts
http://cds.orcad.com/ap_home.asp

Circuit Analysis Modeling: PSPICE - ORCAD... by drjctu

2011年3月24日星期四

直流電壓轉換成交流電壓 ---DC convert to AC

可將T1改成FBT(馳返變壓器)

高速雷射調變電路--- Discrete high-speed laser modulator schematic

http://www.photonlexicon.com/forums/forum.php
This was an early modulatable laser driver that I designed for <300mA diodes. It is capable of very high speed modulation due to its discrete layout, peaking capacitors, and current shunt type modulation, but has drawbacks as a few resistors need to be re-tuned for every different diode type. The power supply needs to be of the regulated type. Also because it is purely a feed-forward design it is very stable with any load wire length/inductance. I don't use this much anymore, so thought I'd release it into the public domain.

D6,V4 are only there to simulate the load laser; R4, V1 and the clock source are for simulation purposes also.

Demo of aliasing for Matlab

% demo of aliasing    2011/3/23 作者:一心の流

close all;
clear all;
clear tt_sf;
DC=2; %直流偏壓
phi= 2*pi/360*270.03;               %相移270.03degree;
freq = 2500000; %freq=fo=發射頻率
samp_freq = 2000000; %freq=fo=發射頻率
n=fix(freq/samp_freq);
freq_nyquist=2*freq;
if samp_freq < freq_nyquist
    freq_alias= freq - n*samp_freq;
else
    freq_alias=0;
end;
time_base=100000000;                 %單位10000 point/per second
time_sweep=0.0001;                     %單位second

optical Receivers for communications

http://www.modulatedlight.org/optical_comms/optical_rx1.html

Receivers for low-bandwidth optical (through-the-air) communications

When designing a receiver that is intended to be used for optical through-the-air communications, there are some things to be considered that are very different from what might be required in most other situations where detection (and demodulation) of an optical signal is to be done:

Weaker signals. Signals are likely weaker in through-the-air communications - typically by several orders of magnitude - than in more familiar situations where an optical signal is to be detected from optical fiber systems such as optical fibers, TOSLINK, infrared TV remote, etc. In thse situations the energy present at the receiver is really quite high, suffering only modest attenuation through the medium. Optical cables tend to have quite low loss, while infrared remotes are usually pointed directly at the device being controlled.

Lower bandwidth. Effective bandwidth is usually lower in long-distance through-the-air communications. For weak-signal detection in through-the-air optical communications and experimentation, voice bandwidth (up to 3 kHz or so) is usually all that is required, while specialized communications techniques (carrier detection, WSJT and WOLF modes) work well with frequencies below 300 Hz. If extreme weak-signal and distance operation is not required, it is possible to use subcarriers into the 10's of kHz and achieve reasonable results.

2011年3月21日星期一

從月球看地球----Current Moon View of the Earth

Current Moon View of the Earth

The current position of the Moon over the Earth is important to Earth-Moon-Earth (EME) moon-bounce communications, because two or more stations on Earth must be able to see the moon simultaneously to communicate.