国产一区国产精品,2019中文亚洲字幕,电影在线高清,欧美精品一区二区三区久久

^{<input id="i6me8"></input>}

計(jì)量論壇

標(biāo)題: 2018年世界計(jì)量日 [打印本頁]

作者: 新聞專員 時(shí)間: 2018-2-8 22:20
標(biāo)題: 2018年世界計(jì)量日
本帖最后由新聞專員于 2018-2-8 22:45 編輯

(, 下載次數(shù): 319)

上傳
點(diǎn)擊文件名下載附件

World Metrology Day

- 20 May -

Welcome to the 2018 World Metrology Day Resource website.

The theme for World Metrology Day 2018 is Constant evolution of the International System of Units. This theme was chosen because in November 2018, the General Conference on Weights and Measures is expected to agree one of the largest changes to the International System of Units (the SI) since its inception. The proposed changes are based on the results of research into new measurement methods that have used quantum phenomena as the basis for standards that are fundamental. The SI will be based on a set of definitions each linked to the laws of physics and have the advantage of being able to embrace further improvements in measurement science and technology to meet the needs of future users for many years to come.

Indeed more widely metrology, the science of measurement, plays a central role in scientific discovery and innovation, industrial manufacturing and international trade, in improving the quality of life and in protecting the global environment.

World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations. The Convention set the framework for global collaboration in the science of measurement and in its industrial, commercial and societal applications. The original aim of the Metre Convention - the world-wide uniformity of measurement - remains as important today as it was in 1875.

The World Metrology Day project is realized jointly by the BIPM and the OIML. We hope that you enjoy this site and that your Country or Metrology Organization will join us and participate in this year's event.

Warm regards,

The WMD Team

來源

http://www.worldmetrologyday.org/

海報(bào)下載

http://www.worldmetrologyday.org/posters.html

Constant evolution of the International System of Units(SI)

The theme chosen forWorld Metrology Day 2018 is Constant evolution of the International Systemof Units (SI). This evolution is a culmination ofmany years of work by a large number of dedicated metrologists to determine thebest method of redefining several of the base SI units. This revision will notdirectly impact legal metrology, since users will be able to obtaintraceability to the revised SI from the same sources used at present. However, itdoes mean that there will be a change in the way we define certain units ofmeasurement and, in some cases, how traceability may ultimately be established.

The revised SI will beentirely based on constants of nature. While this may seem to be a big change,it has in fact already happened several times in the recent past, when both thesecond (1967/68) and the metre (1983) were redefined from being based on theearth’s movement and size to being based on atomic and electromagnetic constants.

The significance inthis case is that certain concepts that were taught to most of us at school andwhich were up to now almost carved in stone, may now change. Theplatinum-iridium (Pt-Ir) prototype that is kept under three locks in a vault nearParis, will go into partial retirement after 137 years of service.

Certainly this willmark the end of an era. The SI started out as the MKS system with human sizedstandards based on what at that time were considered to be invariants of nature:the rotation of the earth, its size, and a weight originally derived from acertain amount of water (later agreed on as a specific amount of Pt-Ir). Bettermeasurements proved over time that those invariants were not in fact asinvariant as previously thought; that fact, together with the technologicaladvances applied to measurements that have gradually allowed for much moreaccurate realization of the units, are the main reasons for the change. Now thelast of those original standards will be replaced by a definition based on a fundamentalconstant of nature.

Although ‘Le Grand K’is the most famous of the SI artifacts, changes will also happen in otherunits. The kelvin will no longer depend on a property of water, the ampere willnot be based on a definition that is very difficult to realize, and the molewill change to a more practical definition. In addition, the reviseddefinitions of the kilogram, ampere, kelvin and mole will have no impact on thedefinitions of the second, the metre and the candela.

As stated earlier, wedo not expect there to be an impact on legal metrology, but it is a significantchange in the thinking and the methods of all of us who have been working with theseunits for many years.

We invite you to takea few minutes to review the many documents available on the BIPM websiterelated to this topic. We also hope you enjoy celebrating World Metrology Daywith us again this year and look forward to once again marking the importancethat metrology plays in the activities of our daily life.

Using the rules of nature to createthe rules of measurement

The International System of Units (SI) is the accepted set of units forall applications of measurement worldwide. Since it was first given the name SInearly 60 years ago, improvements have been agreed to it whenever it has beenpossible to exploit advances in measurement technologies to address newrequirements.

In November 2018, the General Conference on Weights and Measures isexpected to agree one of the most significant changes to the SI which will baseit on a set of definitions each linked to the laws of physics. This historicchange towards using the laws of nature in the definitions will eliminate thefinal link between the SI and definitions based on physical artefacts.Following the revisions, the kilogram will be linked to the exact value of thePlanck constant rather than the International Prototype of the Kilogram, assanctioned by the 1st CGPM in 1889.

For over 200 years,a collective ambition for the “metric system” has been to provide universality of access to the agreed basisfor worldwide measurements. The definitions expected to beagreed in November will be a further step towards this goal. They arebased on the results of research into new measurement methods that have usedquantum phenomena as the basis for standards that are fundamental. Greatattention has been paid to ensure that these new definitions will be compatiblewith the current ones at the time the change is implemented. The changes willbe unnoticeable to all but the most demanding users.

Whilst providing the necessary level ofcontinuity for existing users, the changes have the advantage of being able toembrace future improvements in measurement methods to meet the needs of futureusers because they are based firmly on the laws of physics. The new definitionswill use ‘the rules of nature to create the rules of measurement’ linkingmeasurements at the atomic and quantum scales to those at the macroscopiclevel.

As science and technology progress, thedemands for measurements to underpin new products and services will increase. Metrologyis a dynamic branch of science and the steps taken by the BIPM and the widermetrology community to advance the SI in 2018 will underpin these requirementsand meet these needs for many years to come.

作者: ufoyangyang 時(shí)間: 2018-2-9 02:39
國際單位制的演變過程

作者: 羅羅諾亞索隆 時(shí)間: 2018-2-9 09:28
看不懂洋碼子

作者: 冰河天下 時(shí)間: 2018-2-9 10:48
國際單位制優(yōu)化歷程

作者: x86438751 時(shí)間: 2018-2-9 10:49
國際單位制的持續(xù)演變

作者: lgl_2005 時(shí)間: 2018-2-9 14:44
應(yīng)該是進(jìn)無止境吧

作者: 隨意@ 時(shí)間: 2018-2-11 10:15
嗐英語水平不夠。。。

作者: BXLYLM 時(shí)間: 2018-2-28 15:19
計(jì)量術(shù)語較多，還得好好學(xué)習(xí)英語哦

作者: springwood 時(shí)間: 2018-3-1 12:21
國際單位制進(jìn)化史

歡迎光臨計(jì)量論壇 (http://www.bkd208.com/)

国产一区国产精品,2019中文亚洲字幕,电影在线高清,欧美精品一区二区三区久久