Author: leizhou


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http://bitc.bme.emory.edu/Members/lzhou.html

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Limited by AUTH_SYS, NFS can only handle 16 groups for each user

http://www.insectnation.org/articles/2007/05/08/linux-nfs-16-group-limit/ unless you’d like to suffer the kerberos auth.

Annoyance is not a way of fighting for the future

There are thousands of excuses that the US should tighten the rope around the neck of China. This does not need to be re-listed. However, what is the ultimate goal of all the actions up on China? To suppress its development? To seek a future military victory? To delay the GDP No.1 overtaken? Obviously none […]

Abandoning Deep Space?

Just heard that President Obama is going to slash the funding for going back to the Moon. As well, the sight of NASA would be drown back to near earth space. This is simply a death sentence to the future. The earth is limited, and we are running very close to its limitation of capability, […]

Google: be good, be evil, or be ugly

After a few days of rumor that Google would retreat its Chinese searching business because he claimed of participating the Chinese Government regulation of filtering searching result was evil, after Hilary Clinton has unwisely brought a business debate to a level of international relationship between the two major powers of the world, Google.cn restored all […]

Is there a plot to set down President Obama?

When President Obama moved in the office a year ago, it looked like he got a creative and diligent team. He got a Senate and House ruled by Democrat. He pushed a lot of projects forward for the promised Changes. However, one year later, except for the monster banks who survived from the hole dug […]

Don’t be evil?

This is the motto of Google, which is involved in a rumor that it would leave Chinese market due to the conflicts of its motto and the regulation from the Chinese government, for example, to disclose the emails of gmail users who are suspected illegal by Chinese law enforcement system. Does this stand? As a […]

iMAC G5 frequently loose power?

reason 1)You got a loose power cord; reason 2) Your SMU needs a reset: – Turn off the computer by choosing Shut Down from the Apple menu, or by holding the power button until the computer turns off. – Unplug all cables from the computer, including the power cord. – Wait 10 seconds. – Plug […]

减排本来就是假命题,谈判是没有意义的

碳减排,碳源从哪里来? 人类活动最大的碳源就是燃烧化石燃料. 但是大家都知道,地球上剩余的煤石油天然气按现在水平100~200年就用光了.即便没有协议,到那时,你没得烧,想不减排也得减排.然后自然界自然会恢复平衡. 所以减排是不可避免的自然规律.跟人类谈不谈判没有什么关系. 那么减排为什么会成为国际热点呢? 发达国家真关心小岛国存亡吗? 那只是煽情借口而已. 关键在于,高能耗产业在向发展中国家转移.这已经是不可逆转的趋势.但是,你可能限制发展中国家高能耗产品只出口到发达国家,但是不自己用吗?这显然不可能.那么,原来够发达国家500年用的高能耗工业品,现在发展中国家要留一部分自己用,可能100年就用光了.然后大家同样面临燃料匮乏的衰退痛苦.但是因为发达国家对高能耗工业产品的依赖更大,因此痛苦更深. 这种可预见趋势对发达国家国际地位的影响,是他们无法接受的.因此他们必须想方设法改变这种趋势. 那么怎么改变?碳税就是最理想的方案.碳税将迫使高能耗工业驻在国无偿支付大量产品,削弱其国民消费能力,减少其对高能耗工业品的需求.同时保障了发达国家对高能耗工业品消费能力不下降.从而以抑制发展中国家人民生活水平提高为代价延缓长化石燃料耗尽的到来.同时保持在后化石燃料时代的国际发言权. 这显然是所有发展中国家无法接受的. 反之,发展中国家的要求,发达国家必须补偿发展中国家减排技术的支出,名义上是要他们还碳债,但实质上是迫使发达国家为同样多高能耗工业品支付更多货币,从而削弱发达国家消费能力.同时利用这些额外财富提高本国人民消费能力,缩小和发达国家国力的差距,从而在后化石燃料时代有更大国际发言权. 这两种目标是截然相反的.都是以减排为借口强大自己削弱对手的战略.根本不存在调和的可能.基于一个虚假借口的国际博弈,怎么可能取得任何有倾向性的进展?结果只能是不了了之.这种谈判是没有意义的. 那么是不是只有等化石燃料耗尽,再打一次世界大战才能结果呢?如果那样干,就真是垂死挣扎,自取灭亡了.大战将耗尽人类的能源储备,毁灭人类的尖端科技.之后没有化石燃料的地球勉强能支持10亿人口.然后就是因为生活条件大幅下降造成的饥馑,瘟疫,混乱和杀戮.人类能够免于灭绝恐怕都是奢望了.尽管这是最合乎逻辑的人类未来. 走出这一悲剧未来的唯一途径,甚至不在于非碳能源.因为,大气和水体循环,本身是地球气候调节机制的核心组成.如果从这里面过度提取能源,只能进一步破坏生物圈.这个包括风能,水力,潮汐能等等.至于核能,太阳能,以及地热能,暂且不谈有限的资源.这些能源都为地球生态圈引入附加热能(核能和地热能),或者削弱地球散热机制(太阳能).一旦上了规模,它们对地球气温上升的影响并不小于化石能源.甚至更剧烈–因为化石能源虽然产生温室气体,但同时温室气体促进植物生长,导致碳固定,是存在虽然不足的负反馈抑制机制的.但是核能,太阳能,以及地热能是纯粹加热,没有任何负反馈抑制.认识到这一点,就可以看出减排谈判甚至在科学上都是站不住脚的.只是早死晚死的区别. 那么死定了吗? 当然不是.地球的全部能源来自太阳.地球截面积是3.14×6500^2=1.327亿平方公里。地球距离太阳1.5亿公里,球面积4×3.14×1.5^2=28.26亿亿平方公里。地球仅仅接收了21.3亿分之一的太阳辐射。就是说,如果我们不依赖地球,每个家庭可以采用的能源上限是现有地球的全部能量输入。 从物资上,全球水泥年产量不足20亿吨,粗钢产量不足12亿吨,粮食产量不足25亿吨。这是什么概念? 粮食按低产的,年亩产0.2吨,够低吧。农田有效土壤厚度算半米,够深吧。土壤容重1.15吨每立方米。那么,生产这些粮食需要的土壤总重是47917亿吨。听起来很大。但事实有多少?做一个比重2.65的实心岩石球,直径只有15公里。 矿石算贫的,就算含铁量1%,用矿渣生产水泥,全部水泥粗钢加上其他金属建材,上述产量只需要1200亿吨矿石–做一个比重2.65的实心岩石球,直径只有4.5公里。将这个累计125倍,直径22.5公里。 这就是说,如果人类彻底开采一个直径25公里的小行星,就可以获得20万亿吨的物质,平均每人3333吨。而将全部居民移民到宇宙。 地球,限于化石燃料和有限环境容量,人类加工物质能力只有每年不到1000亿吨。但在太空没有这个限制。一旦第一代千吨级自持矿山制造联合体在宇宙搭建成功,以每年加倍的方式发展,数十年就可以获得每年万亿吨的加工能力,在地球耗尽之前为人类赢得移居空间的能力。从而彻底解决地球困境。 而这个,关键是这个第一步只能从地球发射。而发射密度必须达到每年10000吨级近地轨道运输能力。 这个很可怕吗?人类目前的发射密度是大约每年百次,每次5~10吨。就是说,目前的宇航投资已经在每年扔500吨以上东西上天了。只要再增加20倍,日地空间的窗口即向人类打开。 这很难吗? NASA 2010年的经费不足200亿美元。中国大约200亿人民币。加上欧俄日印,全球不超过400亿美元。但是全球GDP有60万亿美元。航天投资只有0.066%. 而同期全球军费开支1.5万亿美元,占GDP 2.5%. 如果把宇航投资增加30倍,军费削减到现在的1/5,则足以在不影响人类日常生活的基础上打开日地空间窗口。花10年立足小行星。花10年从小行星开始生产空间站,百年之内,就可以开始大规模宇宙移民。人类发展问题即可迎刃而解,生存空间问题将推迟到至少数万年之后。 这个,放眼当今世界,如果“中美国”能够携手,一切垂手可得。何惧宵小熙攘?

linux Oops: I deleted an improtant file, can I undelete?

Linux does not offer a file undelete or unerase mechanism, especially in command line. To undelete a really deleted file, it take guru’s work like in http://www.cyberciti.biz/tips/linuxunix-recover-deleted-files.html This is the last thing one can do.  However, if you take a few precautions, you may save yourself easily. There is a small package named ptrash, which […]

fsck: Couldn’t fix parent of inode : Couldn’t find parent directory entry

In linux file system, when file system error happens, the first choice is to do an fsck of the unmounted file system. Usually, fsck -y /dev/sdxx at boot time should be able to fix everything, if the FS has not been severely damaged. Occasionally, as reported as Debian bug list #478546 at http://groups.google.com/group/linux.debian.bugs.dist/browse_thread/thread/dc48335d2ca42b66 fsck returns […]