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What mean of IP68 or IP69k for electronic device?

IP RATINGS SCALEFirst number - Protection against solids0 No protection. 1 Protected against solid objects greater than 50 mm. 2 Protected against solid objects greater than 12 mm diameter. 3 Protected against solid objects greater than 2.5mm diameter. 4 Protected against solid objects greater than 1.0mm diameter. 5 Dust protected. 6 Dust tight. No Ingress of dust.
Second number - Protection against liquids0 No protection. 1 Protected against vertically dripping water. 2 Protected against dripping water when tilted up to 15°. 3 Protected against spraying water at an angle of up to 60° from vertical. 4 Protected against splashing water when the enclosure is tilted at any angle up to 15°. 5 Protected against water jets from any direction 6 Protected against heavy seas or powerful jets of water. 7 Protected against the effects of short term immersion (under def

Tesla Battery

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Lenovo-YOGA-900

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Processor Up to 6th Generation Intel® Core™ i7 Processor Operating SystemWindows 10 HomeGraphics Up to Intel® Iris™ Graphics 540 Memory Up to 16GB LPDDR3 1866 MHz (Onboard) Webcam 1MP 720p HD CMOS Camera Storage Up to 512GB PCIe SSD AudioJBL® Stereo Speakers with Dolby® DS 1.0Home Theater® CertificationBatteryLocal Video PlaybackUp to 9 hours playback with display brightness set at 200 nitsWiFi BrowsingUp to 10 hours browsing with display brightness set at 200 nitsDisplay 13.3" QHD+ LED IPS Glossy Multi-touch (3200x1800) with integrated camera Dimensions (W x D x H)(inches) : 12.75" x 8.86" x 0.59"<

What is MU-MIMO Technology?

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Multi-user MIMO (MU-MIMO) is a set of multiple-input and multiple-output technologies for wireless communication, in which a set of users or wireless terminals, each with one or more antennas, communicate with each other. In contrast, single-user MIMO considers a single multi-antenna transmitter communicating with a single multi-antenna receiver. In a similar way that OFDMA adds multiple access (multi-user) capabilities to OFDM, MU-MIMO adds multiple access (multi-user) capabilities to MIMO. MU-MIMO has been investigated since the beginning of research into multi-antenna communication, including work by Telatar on the capacity of the MU-MIMO uplink.
SDMA massive MIMO coordinated multipoint (CoMP) and ad hoc MIMO are all related to MU-MIMO; each of those technologies often leverage spatial degrees of freedom to separate users.
Recource from https://en.wikipedia.org/wiki/Multi-user_MIMO

T.A.M Stands for?

Total Addressable Market


Investment managers love investing in companies with a very large T.A.M., in fact many venture capital investors won't invest in a start-up unless the T.A.M. is over $20 billion as more than 50% of companies fail within a few years of being founded. As a result, we always want the ones that do succeed to have an opportunity to be a billion dollar company (in terms of annual revenue). If a company gets 5% marketshare of a $20bn market, then this equals $1bn in revenue. If you can't find the T.A.M., then add up the annual revenue for the top 25 companies in a given sector for an estimate.

为什么中国的英文名字叫China?

说法一: 早在东汉时期,古人就在昌南(现在的景德镇)建造窑坊,烧制陶瓷。到了唐朝,由于昌南土质好,先人们又吸收了南方青瓷和北方白瓷的优点创制出一种青白瓷。青白瓷晶莹滋润,有假玉器的美称,因而远近闻名,并大量出口欧洲。 十八世纪以前,欧洲人还不会制造瓷器,因此中国特别是昌南镇的精美瓷器很受欢迎。在欧洲,昌南镇瓷器是十分受人珍爱的贵重物品,人们以能获得一件昌南镇瓷器为荣。就这样欧洲人就以“昌南”作为瓷器(china)和生产瓷器的“中国”(China)的代称,久而久之,欧洲人就把昌南的本意忘却了,只记得它是“瓷器”,即“中国”了。 西方瓷器原本是从中国输入的。明朝的时候,大批的中国瓷器产品就开始输往西方世界。波斯人称中国的瓷器为chini,欧洲商人在波斯购买中国瓷器也同时把一词带回了西方。后来,他们又把chini改为china,并且把生产china的中国也一并称为China。欧美人谈到China的时候,往往联想到China(中国)是china(瓷器)之乡。 说法二:与瓷器无关——中国为什么叫China? 新民晚报2004年8月3日16版介绍景德镇瓷文化。其文说,宋元两代景德镇的制瓷技术已经传到朝鲜、日本、越南。又说,明清两代瓷器大量出口,经阿拉伯传到欧洲。这些史实,我无异议。唯可疑者,其说china由来,文云:“民间历来有几种说法。一种说法是china系根据秦字读音转化而来。但在景德镇最为流行的说法是china是汉语昌南(原景德镇名)的音译。随着景德镇精白瓷大量流传到海外,才使得瓷(china)成为中国的代名词。” 说china最初是昌南地名译音,我觉得很新鲜。景德镇原名昌南镇,在宋真宗景德年间(1004年起)改名景德镇。此时所制瓷器已负盛名,特供御用。按照“景德镇最为流行的说法”推论,其后本镇瓷器外销朝鲜、日本、越南,又其后经阿拉伯远销到欧洲,皆以产地昌南作为商品名称。昌南两音,口碑远播,写成法文便是chine,写成英文便是china。china又回译成汉文瓷器。瓷器名声响遍全球,欧洲人就把中国也叫作瓷器,而大写其字头,成了China。这个推论亦能自圆其说。 然有极大障碍,景德镇人难以克服。就是至今无人能够否认英文China起源于印度古梵文“支那”。这个支那又作脂那、至那,三千年前就出现了。想想三千年前是什么意思吧。那就是说,什么昌南,什么瓷…

Bose–Einstein condensate

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A Bose–Einstein condensate (BEC) is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero (that is, very near 0 K or −273.15 °C). Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which point macroscopic quantum phenomena become apparent. It is formed by cooling a gas of extremely low density, about one-hundred-thousandth the density of normal air, to ultra-low temperatures. Due to the unique properties of the condensate, it was shown by Lene Hau[1] that light can either be stopped or slowed down significantly to the velocity of 17 meters per second, resulting in an extremely high refractive index.

Resource from Wikipedia Bose–Einstein condensate