2017年10月31日 星期二

雾霾可令中国光伏电站发电效率降低至少六分之一

根據國際能源署的數據,2016年中國新增光伏裝機34GW,這一數字是美國的兩倍還多,佔世界新增裝機容量的近一半。以太陽能為代表的清潔能源若得以替代燃煤為主的發電結構,將極大地改善中國的環境狀況,在清潔能源領域的巨額投資正是中國各級政府的重點舉措之一。
鋪設光伏電板會改善空氣質量,這是我們一直理解的因果關係。但是,反過來呢?尚待改善的空氣質量會不會反過來影響光伏電板發電?
杜克大學的最新研究肯定了我們的疑問,基於NASA GISS的全球氣候模型數據,研究發現,空氣污染中的顆粒物會大規模折損光伏發電效率,幅度甚至可以達到17%以上。
中國有三成光伏發電能力被霧霾耽誤
而短波的太陽輻射光線由於受到灰塵和顆粒物的阻礙,被吸收和散射,這一被稱為太陽光減弱(solar dimming)的現象使得光伏組件接收輻射強度被降低,從而帶來發電損失。根據該研究,以中國目前的光伏發電能力估算,霧霾造成的電力損失高達11GW,這一數字是中國新增光伏裝機容量的近三分之一。
值得注意的是,人為造成的顆粒物對光伏發電的影響超過了自然界的灰塵。研究人員對於光伏組件表面的沉積物進行了採樣和組分分析,發現其中僅有8%是非塵土顆粒物,即人類活動產生的。這8%雖然聽起來不足為慮,但是因為其中含有有機碳、炭黑等成分,碳原子吸收陽光的能力更強;而且由於粒子更小,陽光更容易被散射。也因此,人類活動對於發電效率的損失甚至超過佔比92%的塵土。
世界最大的光伏組件生產商之一英利集團對此感受頗深,技術中心副總經理倪健雄介紹說,英利通過對比並監控自動清潔機器人的光伏組件與常規安裝組件戶外發電量發現:在河北邢台、保定等“著名”的霧霾城市,霧霾時段的發電量可以降低80%以上,在霧霾最為嚴重的時候,幾乎就不發電。
研究團隊成員,杜克大學土木與環境工程系教授Drew Shindell表示,這些由人類活動產生的顆粒物,使得中國比其他國家面臨更為嚴重的光伏發電損失。根據研究,中國中部和東部地區,在每月擦洗一次光伏組件的情況下,顆粒物將造成光伏組件發電效率降低17%~25%;若擦洗間隔為2個月,光伏組件的發電效率則將降低25%~35%。
擦洗很有效,可是光照資源豐富的地方多缺水
中國的地面大型電站對於擦洗並沒有統一標準,一般是通過監控發電量來決定什麼時候擦洗。總部位於山東省青島市的薩納斯新能源科技有限公司專門服務於光伏電站的運營維護,公司總經理耿文強告訴中外對話,從組件維護的角度,現在中國北方的大型地面電站,基本上要保證標準的每年四次擦洗,在污染嚴重的情況下,可以根據現場情況適當增加擦洗頻次。
根據該研究,擦洗後的光伏組件單日發電量會提高50%,效果顯著。
倪健雄表示,毋庸置疑,保持光伏電板的清潔非常重要,提升發電效率的同時,還能有效維護光伏組件,因為顆粒物的長期聚集可能使組件大量發熱,造成熱斑現象,威脅組件壽命。
但是,對於企業而言,更現實的問題是擦洗需要用到的水。在中國光照資源豐富的西北地區,水往往比電珍貴得多,用水量提升發電量是顯然不值得的。耿文強表示,因為擦洗需要大量水資源的投入,是一筆不小的成本,因此企業需要對擦洗投入和發電實際收益進行綜合對比,以此決定擦洗頻次。更專業的光伏運維企業,還會利用光伏大數據分析和挖掘的結果,得出清洗的最佳性價比。
難以控制的系統性風險
分佈式電站其實是霧霾影響的主要受害者。與大型地面電站定期擦洗維護不同,小型的屋頂項目建成後普遍僅依靠雨雪等自然天氣擦洗,缺乏後期運營維護,這進一步加劇了霧霾污染的影響。
愛康科技公關總監張衛紅告訴中外對話,“很少會有居民用戶想到爬上自家的樓頂去擦拭光伏電板”。
空氣質量差,折損清潔能源發電;清潔能源發展的不好,又不利於環境的改善。張衛紅坦言,對於光伏領域的投資者而言,頻發的霧霾天氣增加了一項難以控制的系統性風險。
不過據張衛紅介紹,在中國,政策支持的效力大過商業思維:迫於改善空氣質量的壓力,反倒越是霧霾嚴重的地區,地方政府越有動力推廣地面電站及屋頂光伏項目,減少污染。以霧霾常有爆表的河北保定為例,政府部門曾提出以建設“光伏之都”作為建設低碳城市的重要內容之一,並意向規劃把西部太行山區變成“太行光谷”。該設想如能實現,對於解決京津冀地區的霧霾會有一定的效果。
新加坡能源專家Cleantech Solar公司營運總監Andre Nobre在接受《印度時報》採訪時表示,空氣污染已經成為印度太陽能廠商做出商業決策的重要考量因素,開發商會謹慎考慮在空氣污染嚴重的地區簽署能源採購協議。
霧霾治理的協同效應
頻繁擦洗之外,從源頭上根治空氣污染中的顆粒物,似乎才是更為合宜的選擇。
倪健雄表示,霧霾降低光伏發電效率是短期的陣痛,而下大力氣多方面協同治理,改善整個城市的空氣質量並非天方夜譚。以大同為例,這個曾經在煤坑上的城市如今的空氣質量頗令當地人自豪,而英利集團在大同的“光伏領跑者”基地也運轉良好。Shindell 也從研究的反方向為中外對話做了解讀,“政策越傾向於清潔能源,清潔能源的發展就越好,至少在太陽能領域”。
與印度和阿拉伯半島不同,中國影響光伏發電效率的顆粒物主要來源是人類活動,所以政府有更大的潛力可以減少排放、降低污染。政府有多種手段可以選擇,包括燃料選擇、排放權定價、可再生能源優惠政策。其效益也是顯而易見的,光伏發電量提高之外,考慮到可吸入顆粒物的健康隱患,無疑也會大幅提高人們的健康水平。
另外,這也從另一個角度說明,一邊發展光伏發電一邊繼續修建燃煤火電站的折衷做法可能並不是一個好主意,因為後者會很大程度影響前者的運行。
此文由環境網站“中外對話”授權FT中文網發表。中外對話(https://www.chinadialogue.net/)是一個致力於環境問題的中英雙語網站,總部位於倫敦,是一個獨立的非營利性組織。

2017年10月25日 星期三

Albrecht Dürer's "Map of the Northern Sky" 1515

Albrecht Dürer's "Map of the Northern Sky" is the first printed celestial map, hand-colored on woodcut prints in 1515. Over 500 years later, this captivating image of figures and animals remains an iconic inspiration to scientists and artists everywhere. Learn more about the history of the artistic representation of Astronomy with #Universethebook.
Learn more: http://bit.ly/2xeu5Wc

2017年10月18日 星期三

Type 2 diabetes breakthrough





Type 2 diabetes breakthrough: Scientists create first pill that not only STOPS the condition in its 
tracks but also helps patients lose weight - and it could be available on the NHS within 3 years

Semaglutide allowed 71 per cent of patients to shed pounds from their waistline
Some treatments can trigger slight weight gain, which can fuel type 2 diabetes
If it becomes worse, patients need insulin injections - which can be unpleasant
But the pill, taken alongside metformin, could stop the condition from worsening
Experts have welcomed the findings of the phase II trial, published in JAMA


By Stephen Matthews For Mailonline


PUBLISHED: 16:00 BST, 17 October 2017 | UPDATED: 09:31 BST, 18 October 2017


Scientists have created a new pill that can halt type 2 diabetes in its tracks and help patients shed pounds from their waistlines, a major study has revealed.


Results from a human trial of 632 patients found semaglutide allowed 71 per cent of them to shed pounds - it is believed this is the first type 2 diabetes pill to instigate weight loss.


Researchers hope semaglutide will offer a better way to control the hidden killer, as some treatments currently available can trigger unexpected weight gain which fuels type 2 diabetes.


Results from the phase II trial carried out by the Leicester Diabetes Centre were published in the prestigious JAMA. Semaglutide could be available on the NHS within three years.


The pill was handed as an add-on to patients already taking Metformin - the drug is the first line of defence to control the preventable condition.



Researchers discovered semaglutide stopped type 2 diabetes in its tracks, slashed blood sugar levels and prevented patients from needing insulin.


Type 2 diabetes can lead to heart failure, blindness and leg amputations and is deemed a global time bomb.


Spiraling obesity rates have fuelled a 65 per cent rise in diagnoses in a decade, with more than 4 million people now living with the condition, UK data shows. Globally there are 380 million patients.


Charities have warned the NHS will become crippled by the burden of the condition without urgent action to make changes to today’s lifestyles.



Professor Melanie Davies, lead author, dubbed the results 'hugely promising' and said they show 'semaglutide’s ability to lower HbA1c and support weight loss'.


Semaglutide allowed 71 per cent of patients to lose weight, researchers discovered, as it is believed to be the first of its kind to instigate weight loss (stock)




Offering patients some relief


Lead author Professor Melanie Davies said taking semaglutide as a pill may provide relief to some diabetics who 'struggle injecting themselves'.


She told MailOnline: 'For some patients injectable therapies are a problem, so having something available orally makes it more accessible to some patients.


'We know that it is a bit of a barrier to people and anything that makes treatment more accessible and easier has got to be seen as good.


Professor Davies added: 'Type 2 diabetes is a serious condition with potentially devastating complications which is posing a major challenge to health services across the world because of the increasing numbers of people developing it.







These results demonstrating semaglutide’s ability to have a significant impact on lowering HbA1c and support weight loss when taken orally therefore are hugely promising.'

Experts have welcomed the 'encouraging' findings.

TYPE 2 DIABETES: THE FACTS


Worldwide, there are believed to be around 380 million sufferers. In Britain this has topped 3.8 million, a figure that continues to rise.

The World Health Organization issued a warning to say the world is facing 'a growing diabetes epidemic of potentially devastating proportions' in 2004.

Since 1996, the number of people living with diabetes has more than doubled. The rapid escalation remains of great concern to health bodies.

Type 2 diabetes is caused by having too much glucose in the blood because the body's way of turning it into energy is not working properly.

As the condition progresses, sufferers often need to maintain a healthy diet, exercise and a combination of medications to manage it.

Controlling blood sugar levels are also considered to be the key to reducing the risk of life-changing complications for those already diagnosed.

Someone's life expectancy with type 2 diabetes is likely to be reduced as a result of the condition, by up to 10 years, it is believed.




Oliver Jelley, editor of The Diabetes Times, told MailOnline: 'Type 2 diabetes has become one of the greatest challenges facing the NHS. These latest results are hugely encouraging and will be welcomed across the diabetes community.'





Semaglutide is a glucagon-like-peptide-1 (GLP-1) analogue, a relatively new group of injectable drugs. It can also be taken orally as a pill.

It works by stimulating the production of insulin and suppressing the secretion of the glucose-raising hormone glucagon. The drug also lowers appetite.

How was the study carried out?

Participants were either given semaglutide orally, as an injection or they were given a placebo. They were monitored over 26 weeks.

Each volunteer suffered from type 2 diabetes and had a BMI above or equal to 25 - the medical level that deems adults as overweight.

What else did they find?

As well as the weight loss benefits, the researchers also found reductions of up to 1.9 per cent on average of HbA1c - how blood sugar is measured over time.

The findings mirrored those of the once weekly injection, and proved significantly better than the placebo (0.3 per cent).

Nearly nine tenths of patients receiving oral semaglutide achieved the target HbA1c level of less than 7 per cent.

Healthy adults tend to have HbA1c levels of below 6 per cent, as levels of 6.5 per cent or higher can signal diabetes.

How many sufferers are there?

Figures suggest there are 3.8 million sufferers in the UK - with 90 per cent having type 2. Drugs to treat the conditions cost the NHS a tenth of its yearly budget.

In the US, there are 29 million diabetics, with a similar breakdown between type 1 and 2, with the latter often triggered by poor lifestyles.

Although there are several treatments currently available, many come with risks of developing hypoglycaemia (low blood sugar), as well as weight gain.

If the condition worsens, patients need insulin injections - which many patients find unpleasant.











2017年10月17日 星期二

Google And Levi's Stitch Up A Connected Jacket

Google And Levi’s Stitch Up A Connected Jacket

The new Commuter Trucker denim jacket, powered by Google’s smart textiles, can answer your phone and turn up your music.



Google And Levi's Stitch Up A Connected Jacket
The jacket is the first consumer product to emerge from Project Jacquard, an experimental initiative from Google's Advanced Technology and Projects ...

The good news and bad news about today’s massive Wi-Fi bug


Top stories

Wi-Fi - Wikipedia

https://en.wikipedia.org/wiki/Wi-Fi
Wi-Fi or WiFi is a technology for wireless local area networking with devices based on the IEEE 802.11 standards. Wi-Fi is a trademark of the Wi-Fi Alliance, ...


Wi-Fi安全協議曝出嚴重漏洞

用於連接全世界無線設備的Wi-Fi軟件存在漏洞,可讓黑客得以入侵使用Wi-Fi的設備。密碼專家稱,這是多年來發現的最嚴重漏洞。不過與消費者相比,這個漏洞對大公司的影響可能更大。


 ENLARGE
圖片來源:KRISZTIAN BOCSI/BLOOMBERG NEWS
用於連接全世界無線設備的Wi-Fi軟件存在漏洞,可讓黑客得以入侵使用Wi-Fi的設備,這促使設備生產商匆忙發布補丁程序。
密碼專家稱,一位安全研究人員周一報告的Wi-Fi漏洞是多年來發現的最嚴重漏洞。不過與消費者相比,這個漏洞對大公司的影響可能更大。
利用該漏洞的攻擊方式是,生成一個克隆的無線網絡,以不安全的形式重設受害設備的密鑰,從而暴露之前通過Wi-Fi保護存取協議II (Wi-Fi Protected Access II,簡稱WPA2)加密的任何信息。WPA2被認為是最先進的無線安全技術,已經取代了之前的Wi-Fi安全標準,比如Wi-Fi保護存取協議(WPA)和有線等效加密(WEP)等。
發現該漏洞的比利時魯汶大學(University of Leuven)研究人員Mathy Vanhoef表示,WPA2被攻破,黑客就可以看到通過該無線網絡傳輸的密碼或其他敏感信息。他在自己建立的用以解釋該問題的網站上演示了這種破解方法,他稱之為“密碼重置攻擊”(KRACK)。
Vanhoef寫道,通過Wi-Fi網絡傳輸、但使用其他技術加密的數據不會曝露,比如保護許多網站的基於網絡的HTTPS加密技術。
Vanhoef在一個視頻中展示了這種攻擊方法可能怎樣從連接WPA2無線網絡的安卓(Android)手機中竊取數據。這樣的攻擊要想奏效,黑客首先需要足夠接近其受害設備的無線網絡,以利用特殊設備攔截那個網絡中的路由器、手機和電腦收發的信息。
約翰霍普金斯大學(Johns Hopkins University)計算機科學助理教授Matthew Green稱,單是這一點就足以讓大部分黑客打消攻擊多數消費者網絡的念頭。
他表示,但對於那些下決心攻擊的黑客來說,這提供了從公司網絡中竊取信息的新方法。
蘋果公司(Apple Inc., AAPL)和Alphabet Inc. (GOOG)旗下谷歌(Google)周一稱,預計將在幾周內發布針對受影響設備的補丁程序。微軟(Microsoft, MS)表示,該公司於10月10日發布了補丁程序。
行業組織Wi-Fi聯盟(Wi-Fi Alliance)周一稱,目前還沒有黑客利用該漏洞發起攻擊的跡象。
Wi-Fi聯盟發言人表示,自2006年以來,所有Wi-Fi設備都采用了WPA2,目前在用的幾乎所有Wi-Fi設備都采用這種加密技術。

2017年10月16日 星期一

Mapping the basic units of life

Five Stanford scientists have been selected to develop technologies to complete the Human Cell Atlas, a global collaboration funded by the Chan Zuckerberg Initiative to characterize and map all cells in a healthy human body.
The Human Cell Atlas will be a fundamental resource for scientists, allowing them to better understand how healthy cells work, and what goes wrong when disease strikes.
CHANZUCKERBERG.COM

Ogilby's Britannia, laid out its maps in strips (1675)

Happy #NationalMapReadingWeek! The first accurate road atlas of England and Wales, Ogilby's Britannia, laid out its maps in strips (1675).
This is 'The road from to Oxford to Cambridge', Maps.C.6.d.8, plate 80.

Astronomers Strike Gravitational Gold In Colliding Neutron Stars. Scientists have observed two stars slamming into each other deep in space, sending out huge amounts of gold in an alchemical explosion.


NPR

For the first time, scientists have seen two neutron stars colliding. The impact spewed gold and other heavy elements.



Astronomers Strike Gravitational Gold In Colliding Neutron Stars
In an astonishing discovery, astronomers used gravitational waves to locate two neutron stars smashing together. The collision created 200 Earth masses of pure gold, along with other elements.
NPR.ORG

California Institute of Technology - Caltech
"Cosmic gold" has a certain ring to it, don't you think? #GravitationalWaves #GW170817

After being alerted to a gravitational-wave event by LIGO and its European counterpart Virgo, thousands of scientists across the globe looked at a patch of sky and saw the aftermath of a neutron star collision, marking the first time such an event has been observed with both gravitational-wave and c...
CALTECH.EDU


The Independent
BREAKING

Two stars slammed into each other deep in space, sending out huge amounts of gold in an alchemical explosion. The super-dense stars crashed 130 million light years away, spewing out precious metals and other heavy elements like platinum and uranium, scientists say. And now the explosion has kickstar...
INDEPENDENT.CO.UK
內有多個影片:"This tells us that the heavy elements, like the gold or platinum in jewellery, are the cinders forged in the billion degree remnants of a merging neutron star."“這告訴我們,重金屬,如珠寶中的黃金或鉑金,是中子星合併時的十億度高溫所鍛燒殘餘物(灰泥)。”


Scientists have observed two stars slamming into each other deep in space, sending out huge amounts of gold in an alchemical explosion.

The super-dense stars crashed together 130 million light years away, spewing out precious metals and other heavy elements like platinum and uranium – and experts say the event has kickstarted a "new chapter in astrophysics" and confirmed theories about the origin of the mysterious neutron stars.

The huge explosion rocked the fabric of the universe, distorting spacetime. That is a major discovery in itself, marking only the fifth time that gravitational waves have been spotted on Earth.

Nasa's most stunning pictures of space

Scientists didn't just "hear" the violent blast by seeing the ripples in spacetime. They were also able to use telescopes on satellites and the ground to see the light and radiation that was being flung out of the explosion, which is known as a "kilonova".

And that information is going to be relied on for years to come as scientists learn more about the beginnings of such stars, and even our entire universe, astronomers said.


READ MORE

Out of control Chinese space station about to fall to Earth


Every other gravitational wave detection has been traced to black holes crashing together in remote regions of the universe more than a billion light years away.

The new event – though still very distant – was much closer and completely different in nature. It was caused by colliding neutron stars – burned out remnants of giant stars so dense that a teaspoon of their material on Earth would weigh a billion tons.

The two objects, each about 12 miles in diameter, stretched and distorted spacetime as they spiralled towards each other and finally collided.


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Take a minute to see why players across the world are crazy about this gameVikings: Free Online Game

The Ultimate Cheap Flights Finder is Here!Save70.com
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Like ripples from a stone thrown in a pond, the gravitational waves fanned out across the universe at the speed of light.

They were picked up on Earth by two incredibly sensitive detectors in Washington and Louisiana in the US, operated by the Laser Interferometer Gravitational-Wave Observatory (Ligo).

It was here the first discovery of gravitational waves was made in September 2015, confirming a prediction made by Albert Einstein 100 years ago and earning three pioneers of the project a Nobel Prize.

Two seconds after the Ligo detection, a burst of gamma rays from the neutron star collision was captured by Nasa's Fermi space telescope.

Astronomers around the world quickly turned their telescopes and dishes towards a small patch in the southern sky and also saw the flash across the visible and invisible light spectrum.


0:00/0:43
Nasa is hiring a 'planetary protection officer' to defend Earth from aliens

Analysis of the light revealed something astonishing – the manufacture of gold on a cosmic scale, as well as other heavy elements.

Dr Joe Lyman from the University of Warwick, one of many British scientists involved, said: "The exquisite observations obtained in a few days showed we were observing a kilonova, an object whose light is powered by extreme nuclear reactions.

"This tells us that the heavy elements, like the gold or platinum in jewellery, are the cinders forged in the billion degree remnants of a merging neutron star."

The origins of gold and other heavy elements have been a long-standing mystery, but recent evidence has suggested that colliding neutron stars could have a hand in their creation.

A third gravitational wave facility called Virgo near Pisa, Italy, also registered a faint signal from the event, allowing scientists to triangulate its position.

The neutron star collision took place 130 million light years away in a relatively old galaxy called NGC 4993. When the gravitational waves began their journey across space, dinosaurs roamed the Earth.

The gravitational wave signal, named GW170817, was detected at 1.41pm UK time on August 17.

Ligo's detectors, consisting of L-shaped tunnels with arms 2.5 miles long, use laser beams bouncing off mirrors to measure movement across a distance 10,000 times smaller than the width of a proton, the kernel of an atom.


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A tight lid was kept on the findings until the publication of a series of papers in journals including Nature, Nature Astronomy, and Physical Review Letters.

The international researchers expect to spend many months trawling through the mountain of data.

One question already answered is the origin of short-duration gamma ray bursts. Gamma ray bursts (GRBs), marked by an eruption of gamma rays lasting milliseconds to several minutes, are the most powerful explosions known to science.

Scientists now know that one type of GRB is generated when neutron stars collide.

Dr Samantha Oates, also from the University of Warwick, said: "This discovery has answered three questions that astronomers have been puzzling for decades: what happens when neutron stars merge? What causes the short duration gamma-ray bursts? Where are the heavy elements, like gold, made?

"In the space of about a week all three of these mysteries were solved."

Colleague Dr Danny Steeghs said: "This is a new chapter in astrophysics."

British Ligo scientist Professor BS Sathyaprakash, from the University of Cardiff, described the new discovery as "truly a eureka moment".

He added: "The 12 hours that followed are inarguably the most exciting hours of my scientific life. This event marks a turning point in observational astronomy and will lead to a treasure trove of scientific results."

Professor Bernard Schutz, also from the University of Cardiff, told how his team used the gravitational wave detections to measure the expansion of the universe more accurately than had ever been achieved before.

"What has amazed me ... is that with just this one measurement, we got a result right in the middle between the two rather different values that astronomers have measured recently," he said.

Dr David Shoemaker, spokesman for the Ligo scientific collaboration and senior research scientist at the US Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research, said: "From informing detailed models of the inner workings of neutron stars and the emissions they produce, to more fundamental physics such as general relativity, this event is just so rich.

"It is a gift that will keep on giving."

Ligo colleague Professor Laura Cadonati, from Georgia Institute of Technology, US, said: "This detection has genuinely opened the doors to a new way of doing astrophysics.

"I expect it will be remembered as one of the most studied astrophysical events in history."

Additional reporting by agencies