给X61装系统

1，首先，你要有一个系统安装盘的ISO文件；
2，其次，准备一个U盘，装XP的话1G足够，Vista或Win 7可能要4G以上；
3，安装一个叫Ultra ISO的软件（当然在另外一台电脑上！）
4,用Ultra ISO打开那个ISO文件，然后选择“启动光盘”-》“写入硬盘映像”，写入U盘，记得格式选USB-ZIP+；
5，然后把X60设为USB硬盘启动，用刚才的U盘就可以像光盘一样装系

http://www.top81.ws/show.php?f=1&t=974419&m=6857975

install XP in T20, after using Linux

phenomenon --> stop right after the CD is reading, result in a black screen after "Setup is inspecting your computer's hardware configuration" ==> reason: the linux partition confused the XP ==> solution: use partition tool to remove the Linux partition. the best tool could be "

GParted"

http://gparted.sourceforge.net/download.php

it is a live CD and can be used to boot. if the graphic failed to start. go to the sbin to start the "parted" exe file directly. I don't know the password for the superuser. however, this one doesn't require this. use the "print" command to see the current hd and use the command of "rm number" to remove the partition. don't need to create one. reboot and the XP installation run smoothly.

useful links

http://forum.thinkpads.com/viewtopic.php?p=366364&sid=afc697094fc5ce74af9279a97e68d1c3

Windows XP clean installation - ThinkPad General
http://www-307.ibm.com/pc/support/site.wss/document.do?lndocid=MIGR-40068

飞机加油问题

已知

1. 每个飞机只有一个油箱
2. 飞机之间可以相互加油(注意是相互，没有加油机)
3. 一箱油可供一架飞机绕地球飞半圈
4. 所有飞机从同一机场起飞，而且必须都安全返回机场，不允许中途降落，中间没有飞机场

问题：

为使至少一架飞机绕地球一圈回到起飞时的飞机场，至少需要出动几架飞机?

5

the 1st one come back at the point the angle is 45, the 2second come back at the point where the angle is 90. one plane keep flying. the third one flies to this one in the opposite direction to the location where the angle is 90. the fourth feuls the plane at the point where the angle is 45

toaster

总共有3000只香蕉，有一只骆驼每一次只能带 1000只香蕉，每1公里吃1只香蕉，没有香蕉吃
它是不肯走的，A-B 点距离1000公里，如果这个骆驼要从A点到B点有什么办法可以让更
多的香蕉剩下来？如何做到？如何最有效率的运最多的香蕉到B点？

第一次到200Km处放下600橡胶返回
第二次到2OOKm处再装上200橡胶前行，到533KM处放下334橡胶返回，返程中在200Km在装200
第三次在200Km处装上200橡胶前行，在533Km处装上333橡胶前行，此时还是满载1000橡胶
最后剩下533橡胶
问题的焦点在于，如何使最后满载点（1000香蕉）离终点最近？而此时已经消耗了2000=2X(第一次距离）+3Y（第二次距离），所以还得必须使X最短，而5X大于等于1000才不至于浪费（丢在路上）橡胶。

故第一次200Km
第二次533Km

(1) it can be proved that the intermidate points must be the same.

(2) the first distance can be 100m, 200m, etc. it makes no difference. the key point is to reduce the number of rounds. comsuming the first 1000 bannas. divided by 5, then it is 200m. the second round, divided by 3

这个问题是不是可以这么延伸:

3k 香蕉 路上停两次, 4K香蕉 是不是就变成

2x + 2y + 3z = 3000

并且 7x >= 1000, 5 (y-x) >= 1000

x = 142 y = 342 z = 675

5k 香蕉 就是

111, 253, 453, 786

以此类推, n k 香蕉最佳路径为

point 1 = 1000/ (2n-1),
point 2 = p1 + 1000 / (2n-3)
point 3 = p2 + 1000 / (2n-5)
...
keep this until (2n-x) <= 1


基本上就是每进一步都消耗1000香蕉, 这样不浪费运力

到2n-1 > 15的时候, 开始溢出, 保证能运到终点, 也就是需要8k香蕉, 保证必有至少1k香蕉到终点...

TCP Sockets vs UNIX Domain Sockets

http://www.rodrickbrown.com/blog/

TCP Sockets vs UNIX Domain Sockets

Aug 6th, 2008 by admin

- UNIX domain sockets use the file system as the address name space. This
means you can use UNIX file permissions to control access to communicate
with them. I.e., you can limit what other processes can connect to the
daemon — maybe one user can, but the web server can’t, or the like.
With IP sockets, the ability to connect to your daemon is exposed off
the current system, so additional steps may have to be taken for
security. On the other hand, you get network transparency. With UNIX
domain sockets, you can actually retrieve the credential of the process
that created the remote socket, and use that for access control also,
which can be quite convenient on multi-user systems.

- IP sockets over localhost are basically looped back network on-the-wire
IP. There is intentionally “no special knowledge” of the fact that the
connection is to the same system, so no effort is made to bypass the
normal IP stack mechanisms for performance reasons. For example,
transmission over TCP will always involve two context switches to get to
the remote socket, as you have to switch through the netisr, which
occurs following the “loopback” of the packet through the synthetic
loopback interface. Likewise, you get all the overhead of ACKs, TCP
flow control, encapsulation/decapsulation, etc. Routing will be
performed in order to decide if the packets go to the localhost.
Large sends will have to be broken down into MTU-size datagrams, which
also adds overhead for large writes. It’s really TCP, it just goes over
a loopback interface by virtue of a special address, or discovering that
the address requested is served locally rather than over an ethernet
(etc).

- UNIX domain sockets have explicit knowledge that they’re executing on
the same system. They avoid the extra context switch through the
netisr, and a sending thread will write the stream or datagrams directly
into the receiving socket buffer. No checksums are calculated, no
headers are inserted, no routing is performed, etc. Because they have
access to the remote socket buffer, they can also directly provide
feedback to the sender when it is filling, or more importantly,
emptying, rather than having the added overhead of explicit
acknowledgement and window changes. The one piece of functionality that
UNIX domain sockets don’t provide that TCP does is out-of-band data. In
practice, this is an issue for almost no one.

In general, the argument for implementing over TCP is that it gives you
location independence and immediate portability — you can move the client
or the daemon, update an address, and it will “just work”. The sockets
layer provides a reasonable abstraction of communications services, so
it’s not hard to write an application so that the connection/binding
portion knows about TCP and UNIX domain sockets, and all the rest just
uses the socket it’s given. So if you’re looking for performance locally,
I think UNIX domain sockets probably best meet your need. Many people
will code to TCP anyway because performance is often less critical, and
the network portability benefit is substantial.

Right now, the UNIX domain socket code is covered by a subsystem lock; I
have a version that used more fine-grain locking, but have not yet
evaluated the performance impact of those changes. I’ve you’re running in
an SMP environment with four processors, it could be that those changes
might positively impact performance, so if you’d like the patches, let me
know. Right now they’re on my schedule to start testing, but not on the
path for inclusion in FreeBSD 5.4. The primary benefit of greater
granularity would be if you had many pairs of threads/processes
communicating across processors using UNIX domain sockets, and as a result
there was substantial contention on the UNIX domain socket subsystem lock.
The patches don’t increase the cost of normal send/receive operations, but
due add extra mutex operations in the listen/accept/connect/bind paths.

Robert N M Watson

English

thank you for banking with xx. we truly appreciate your business. please don't hesitate to contact e with any questions. Sincerely,

The Nereus engineering team knew that, to reach these depths, a tethered robot using traditional technologies would be prohibitively expensive to build and operate.

used unique technologies and innovative methods to strike a balance between size, weight, materials cost, and functionality.

Building on previous experience developing tethered robots and autonomous underwater vehicles (AUVs) at WHOI and elsewhere, the team fused the two approaches together to develop a hybrid vehicle that could fly like an aircraft to survey and map broad areas and then be converted at sea into a tethered, remotely operated vehicle (ROV) that can hover like a helicopter near the seafloor to conduct experiments or to collect biological or rock samples under real-time human control.

The tethering system presented one of the greatest challenges in developing a cost-effective ROV capable of reaching these depths.

If such a cable were used to reach the seafloor in the Mariana Trench, it would snap under its own weight.

To solve this challenge, the Nereus team adapted .. to carry real-time video and other data between the Nereus and the surface crew

Similar in diameter to a human hair and with a breaking strength of only 4 kilograms (8.8 pounds), the tether is composed of glass fiber core

Another weight-saving advance of the vehicle is its use of ceramic spheres for flotation, rather than the much heavier traditional syntactic foam used on vehicles like the submersible Alvin or the ROV Jason. to withstand crushing pressures.

make effective use of the vehicle's limited battery power.

It allows vast areas to be explored with great effectiveness.

but unleashing a capability that now enables deep exploration, unencumbered by a heavy tether and surface ship,

A one-hour documentary produced by Discovery Studios will air on Science Channel

we’re eager for Nereus to become widely used to explore the most inaccessible reaches of the ocean

its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.

If
any one provide me questions or any other way of
getting the questions or accessing the brainbench then
it will be of great help.

Thanks in advance.

proxy

1下载安装tor: http://download.pchome.net/internet/server/router/download-34060.html
2 下载安装firefox网络浏览器（以取代微软的ie）
3 最后，再下载 https://addons.mozilla.org/firefox/2275/

然后在你FIREFOX右下角就有个TOR按钮，点一下就可以绕过屏蔽，恢复正常再点一下即可.