プロシーディングスについては、カンファレンスの名称をCORE ランク http://portal.core.edu.au/conf-ranks/ で調べる。世界的に認められているカンファレンスならばほぼ必ずヒットするはずです。このときの「Rank」に注目しましょう。難易度が高い順にA*、A、B、Cとなります。A*やAはトップレベルとされているので、そのランクにコンスタントに採録されている研究室は相当な実力だと言えます。
ジャーナルについては、impact factor(IF値)について調べる。IF値が高いほど難易度が高いということです。

では、ジャーナルとプロシーディングスはどっちの方が偉いかというと、簡単には優劣が付きません。

他の分野ではジャーナルが第一なのですが、コンピュータサイエンス特有(？)の大きな特徴として「そこらのジャーナルよりも、トップレベルのプロシーディングスの方が上」ということが挙げられます。

ですので、ジャーナルが多いからこの先生は凄いとか、ジャーナルが少ないからこの先生はヤバイ、と考えるのはコンピュータサイエンスに限っては違うと考えましょう。

また一部の教員には、CORE ランクに載ってないような学会での発表は業績リストに入れない、という人がいます。

このように主要な業績のみからなる業績リストをSelective Publicationといいます。

Selective Publicationのみを公開してる人と、単純に学会に論文を出してない人は区別する必要があります。

最後に

色々挙げてきましたが、「結局どれを優先して見るべきか」というのは難しいところがあります。

しかし間違いなく言えることがあって、業績を全く挙げてない人が大型予算を確保できることはありえませんし、優秀な教員の下には優秀なスタッフがついてくるものです。

つまり、これらの要素はお互いに作用しあっているので、今まで挙げたうちの1つでも「あ、この研究室凄そうだ」というのがあれば、少なくとも地雷を踏むことはないと思います。

せっかく個人としての能力は優秀なのに、研究室選びで失敗してしまい、折れてしまった人を今まで何人か見てきました。この記事でそういう人が1人でも減ってくれることを祈ってます。

Permalink | 記事への反応(0) | 08:41

2015-11-08

■世界記憶遺産：意見書　 日本、「南京」否定派を引用　 ユネスコ受け入

意見書は明星大の高橋史朗教授が作成した。
・・・
外務省関係者は「（高橋教授は）保守派の中ではバランスの取れた研究者だ」と話している。
http://mainichi.jp/shimen/news/20151106ddm001040141000c.html

まともな研究者かどうかは、政治家はともかく、外務省はきちんと判断できないと非常にヤバい。

ブコメの反応が的を得ている http://b.hatena.ne.jp/entry/mainichi.jp/shimen/news/20151106ddm001040141000c.html

その分野の学位を持たない研究者の意見なんて国際的に通用しない http://bit.ly/1LUP6Dj という国際感覚が外務省に無いのがヤバい。
研究業績のImpact Factor ゼロでかつ断定調で発言する学者は高確率でトンデモ。国の意思決定から外すべき。Citationが全てではないが、少なくともまともなピアレビューを受けた事がない学者に国民の生活を預けてはいけない。
高橋史朗が思想的にバランス取れてると国家から認定されるとか、この国はもはや救いようがない段階まで堕ちてる。
重要な場面でなぜ不適切な人物が代表やまとめ役になるのか。ほんとおかしい。
なんでここまで知性ミニマリストが吹き溜まっちゃってんの、昨今の外務省って。重光葵氏とか石射猪太郎氏とか法眼晋作氏とか日高信六郎氏とかの諸先輩の著述もみんなインチキ呼ばわりするつもり？
東中野の研究が「まともな研究」とかおよそ大学でまともに勉学に励めば出てこないセリフだわ。
政府がアホ揃いなのは今さらだとして、外務省もこの体たらくかよ。外交の専門家としてそんな意見は国際社会じゃ一蹴されるだけだとアドバイスするのが仕事だろうに、どんな美味な毒まんじゅうを食わされたのやら
裁判所から「学問研究に値しない」と言い切られた東中野かよ。古いわ価値はないわ……/中韓が掘り返すという人よ、日本政府が大前提まで覆そうとしているというメッセージになりうるこれを、どう評価するんだ？

Permalink | 記事への反応(0) | 06:41

2013-09-09

■http://anond.hatelabo.jp/20130909164812

たくさん論文を書いてたら偉いわけでもないし、
論文誌に掲載された論文の主張が常に正しいというわけではないし、
論文誌も学会もピンからキリまであるし、

そのためにimpact factorも決まってるし、あんたが何なのかしらんけど、ちゃんとした基準に出来るようにはなってるので。

そして、たとえ論文になってるとしても、誰もがそれを神様の様に拝めるわけでもなしで、常に検証は行われてるわけで。

その辺ちゃんと知った上で理論を展開しないと、｢自称学者｣以下のただの｢知ったかのバカ｣だよ。

Permalink | 記事への反応(0) | 17:11

2012-06-24

■The inevitable decline of CDs

http://www.dailytitan.com/2011/04/the-inevitable-decline-of-cds/より転載：

Almost 11 years ago, stores like Tower Records and Wherehouse Music were mobbed with over 2.4 million people waiting to purchase N'Sync's No Strings Attached album.

Today, music stores like those are almost non-existent, and those that are still in business do not receive much foot traffic in the CD aisles.

The sales of compact disc albums have seen a significant decline since that record week in 2000. Nielsen Sound Scan reported that over 730 million units sold in 2000. In 2010, album sales hit an all-time low of 326 million units sold, including digitally downloaded albums.

"Nobody wants to go through the trouble of going to a music store, finding and buying a CD, opening the package, etc. Now we just click a button on the Internet and instantly have music," said Keegan Gogerty, 22, a singer/songwriter and radio-TV-film student.

Digitally downloading music has played a major role in the decline of CD sales, but the biggest factor is the illegal digital downloading of music.

Pirating music has been on the rise since Napster launched its peer-to-peer file-sharing software in 1999. Napster was known for allowing users to share and trade their MP3 files with one another over the Internet for free.

Napster was later shut down after multiple lawsuits, but more peer-to-peer outlets surfaced, such as Kazaa, Morpheus and LimeWire.

Peer-to-peer sharing has grown from MP3 sharing to multiple-file sharing and torrent sharing.

"I don't blame people for not wanting to purchase music. If I want to support a band, I will attend their concerts or buy a T-shirt. That is where they receive the most royalties anyway," said Charlie Hatano, an advertising graduate student.

"We live in a generation of simple living, the digital age," Gogerty said.

Online music stores such as iTunes and Napster give consumers the option to purchase music at the click of a button.

However, Ashley Sutton, 24, a psychology major, still buys compact discs.

"Nothing beats getting a new CD, reading the booklet and reading the lyrics," said Sutton. "I agree Internet downloading is more convenient, but I find owning a physical CD collection rewarding, rather than clogging up my computer with music I download."

The music industry has tried to crack down on the peer-to-peer file-sharing software programs, but people are still using different forms of illegally downloading or sharing music.

"I'll admit that I have had friends burn an album for me or copy them into my computer for my iPod," Sutton said. Making copies of CDs, illegally downloading the album and sharing, it is all the same.

In an interview with USAToday.com, the Recording Industry Association of America's (RIAA) CEO said illegal music sharing has been "contained."

"I remember people downloading one song at a time with Napster. More recently I have seen people download 10 albums at the same speed they could download one song in 1999," Hatano said.

Permalink | 記事への反応(0) | 17:27

2012-01-05

■Types of digital cameras

Digital cameras are made in a wide range of sizes, prices and capabilities. The major ity are camera phones, operated as a mobile application through the cellphone menu. Professional photographers and many amateurs use larger, more expensive digital single-lens reflex cameras (DSLR) for their greater versatility. Between these extremes lie digital compact cameras and bridge digital cameras that "bridge" the gap between amateur and professional cameras. Specialized cameras including multispectral imaging equipment and astrographs continue to serve the scientific, military, medical and other special purposes for which digital photography was invented.

[edit]Compact digital cameras

Subcompact with lens assembly retracted

Compact cameras are designed to be tiny and portable and are particularly suitable for casual and "snapshot" uses. Hence, they are also called point-and-shoot cameras. The smallest, generally less than 20 mm thick, are described as subcompacts or "ultra-compacts" and some are nearly credit card size.[2]

Most, apart from ruggedized or water-resistant models, incorporate a retractable lens assembly allowing a thin camera to have a moderately long focal length and thus fully exploit an image sensor larger than that on a camera phone, and a mechanized lens cap to cover the lens when retracted. The retracted and capped lens is protected from keys, coins and other hard objects, thus making it a thin, pocketable package. Subcompacts comm only have one lug and a short wrist strap which aids extraction from a pocket, while thicker compacts may have two lugs for attaching a neck strap.

Compact cameras are usually designed to be easy to use, sacrificing advanced features and picture quality for compactness and simplicity; images can usually only be stored using lossy compression (JPEG). Most have a built-in flash usually of low power, sufficient for nearby subjects. Live preview is almost always used to frame the photo. Most have limited motion picture capability. Compacts often have macro capability and zoom lenses but the zoom range is usually less than for bridge and DSLR cameras. Generally a contrast-detect autofocus system, using the image data from the live preview feed of the main imager, focuses the lens.

Typically, these cameras incorporate a nearly silent leaf shutter into their lenses.

For lower cost and smaller size, these cameras typically use image sensors with a diagonal of approximately 6 mm, corresponding to a crop factor around 6. This gives them weaker low-light performance, greater depth of field, generally closer focusing ability, and smaller components than cameras using larger sensors.

Starting in 2011, some compact digital cameras can take 3D still photos. These 3D compact stereo cameras can capture 3D panoramic photos for play back on a 3D TV.[3] Some of these are rugged and waterproof, and some have GPS, compass, barometer and altimeter. [4]

[edit]Bridge cameras

Sony DSC-H2

Main article: Bridge camera

Bridge are higher-end digital cameras that physically and ergonomically resemble DSLRs and share with them some advanced features, but share with compacts the use of a fixed lens and a small sensor. Like compacts, most use live preview to frame the image. Their autofocus uses the same contrast-detect mechanism, but many bridge cameras have a manual focus mode, in some cases using a separate focus ring, for greater control. They originally "bridged" the gap between affordable point-and-shoot cameras and the then unaffordable earlier digital SLRs.

Due to the combination of big physical size but a small sensor, many of these cameras have very highly specified lenses with large zoom range and fast aperture, partially compensating for the inability to change lenses. On some, the lens qualifies as superzoom. To compensate for the lesser sensitivity of their small sensors, these cameras almost always include an image stabilization system to enable longer handheld exposures.

These cameras are sometimes marketed as and confused with digital SLR cameras since the appearance is similar. Bridge cameras lack the reflex viewing system of DSLRs, are usually fitted with fixed (non-interchangeable) lenses (although some have a lens thread to attach accessory wide-angle or telephoto converters), and can usually take movies with sound. The scene is composed by viewing either the liquid crystal display or the electronic viewfinder (EVF). Most have a longer shutter lag than a true dSLR, but they are capable of good image quality (with sufficient light) while being more compact and lighter than DSLRs. High-end models of this type have comparable resolutions to low and mid-range DSLRs. Many of these cameras can store images in a Raw image format, or processed and JPEG compressed, or both. The major ity have a built-in flash similar to those found in DSLRs.

In bright sun, the quality difference between a good compact camera and a digital SLR is minimal but bridgecams are more portable, cost less and have a similar zoom ability to dSLR. Thus a Bridge camera may better suit outdoor daytime activities, except when seeking professional-quality photos.[5]

In low light conditions and/or at ISO equivalents above 800, most bridge cameras (or megazooms) lack in image quality when compared to even entry level DSLRs. However, they do have one major advantage: their much larger depth of field due to the small sensor as compared to a DSLR, allowing larger apertures with shorter exposure times.

A 3D Photo Mode was introduced in 2011, whereby the camera automatically takes a second image from a slightly different perspective and provides a standard .MPO file for stereo display. [6]

[edit]Mirrorless interchangeable-lens camera

Main article: Mirrorless interchangeable-lens camera

In late 2008, a new type of camera emerged, combining the larger sensors and interchangeable lenses of DSLRs with the live-preview viewing system of compact cameras, either through an electronic viewfinder or on the rear LCD. These are simpler and more compact than DSLRs due to the removal of the mirror box, and typically emulate the handling and ergonomics of either DSLRs or compacts. The system is used by Micro Four Thirds, borrowing components from the Four Thirds DSLR system.

[edit]Digital single lens reflex cameras

Cutaway of an Olympus E-30 DSLR

Main article: Digital single-lens reflex camera

Digital single-lens reflex cameras (DSLRs) are digital cameras based on film single-lens reflex cameras (SLRs). They take their name from their unique viewing system, in which a mirror reflects light from the lens through a separate optical viewfinder. At the moment of exposure the mirror flips out of the way, making a distinctive "clack" sound and allowing light to fall on the imager.

Since no light reaches the imager during framing, autofocus is accomplished using specialized sensors in the mirror box itself. Most 21st century DSLRs also have a "live view" mode that emulates the live preview system of compact cameras, when selected.

These cameras have much larger sensors than the other types, typically 18 mm to 36 mm on the diagonal (crop factor 2, 1.6, or 1). This gives them superior low-light performance, less depth of field at a given aperture, and a larger size.

They make use of interchangeable lenses; each major DSLR manufacturer also sells a line of lenses specifically intended to be used on their cameras. This allows the user to select a lens designed for the application at hand: wide-angle, telephoto, low-light, etc. So each lens does not require its own shutter, DSLRs use a focal-plane shutter in front of the imager, behind the mirror.

[edit]Digital rangefinders

Main article: Rangefinder camera#Digital rangefinder

A rangefinder is a user-operated optical mechanism to measure subject distance once widely used on film cameras. Most digital cameras measure subject distance automatically using electro-optical techniques, but it is not customary to say that they have a rangefinder.

[edit]Line-scan camera systems

A line-scan camera is a camera device containing a line-scan image sensor chip, and a focusing mechanism. These cameras are almost solely used in industrial settings to capture an image of a constant stream of moving material. Unlike video cameras, line-scan cameras use a single row of pixel sensors, instead of a matrix of them. Data coming from the line-scan camera has a frequency, where the camera scans a line, waits, and repeats. The data coming from the line-scan camera is comm only processed by a computer, to collect the one-dimensional line data and to create a two-dimensional image. The collected two-dimensional image data is then processed by image-processing methods for industrial purposes.

Further information: Rotating line camera

[edit]Integration

Many devices include digital cameras built into or integrated into them. For example, mobile phones often include digital cameras; those that do are known as camera phones. Other small electronic devices (especially those used for communication) such as PDAs, laptops and BlackBerry devices often contain an integral digital camera, and most 21st century camcorders can also make still pictures.

Due to the limited storage capacity and general emphasis on convenience rather than image quality, almost all these integrated or converged devices store images in the lossy but compact JPEG file format.

Mobile phones incorporating digital cameras were introduced in Japan in 2001 by J-Phone. In 2003 camera phones outsold stand-alone digital cameras, and in 2006 they outsold all film-based cameras and digital cameras combined. These camera phones reached a billion devices sold in only five years, and by 2007 more than half of the installed base of all mobile phones were camera phones. Sales of separate cameras peaked in 2008. [7]

Integrated cameras tend to be at the very lowest end of the scale of digital cameras in technical specifications, such as resolution, optical quality, and ability to use accessories. With rapid development, however, the gap between mainstream compact digital cameras and camera phones is closing, and high-end camera phones are competitive with low-end stand-alone digital cameras of the same generation.

[edit]Waterproof

A Canon WP-1 waterproof 35 mm film camera

Waterproof digital cameras are digital cameras that can make pictures underwater. Waterproof housings have long been made but they cost almost as the cameras. Many waterproof digital cameras are shockproof and resistant to low temperatures; one of them is Canon PowerShot D10, one of the first underwater digital cameras.

These cameras become very popular during the holiday seas on, because many people want to save the best moments from their holidays at the seaside. Waterproof watches and mobile phones were produced earlier. Most makers of digital cameras also produce waterproof ones and every year they launch at least one new model, for example Sony, Olympus, Canon, Fuji.

Healthways Mako Shark, an early waterproof camera,[8] was launched in 1958 and cost around 25 dollars. It was a huge camera and pictures were black and white.

___________________________

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Permalink | 記事への反応(0) | 15:08

2011-12-15

■Critical Thinking: Film Critics Across the Country Name Their Top Movies and Actors

"The Artist"? "The Descendants"? "Hugo"? There was no critical consensus following a day of intense voting yesterday when a gaggle of critics groups voted their top honors. These included the Los Angeles Film Critics Association (LAFCA), the Boston Society of Film Critics (BSFC), and the New York Film Critics Online (NYFCO), as well as critics in San Francisco, Detroit and Indiana. The American Film Institute also announced its annual top 10, typically taking no risks.

Best Picture: "The Descendants" got a strong push with a win at the LAFCA, but "The Artist" took the top prize at the BSFC and the NYFCO. Both titles will make the final Academy shortlist. Fortified by nominations for their respective directors Martin Scorsese and Terrence Malick, "Hugo" and "The Tree of Life" should get nominations. The critics groups didn't get "The Help," any more than "The Blind Side," but the Civic Rights-era drama did make the American Film Institute top ten this year, so don't discount it yet.

Best Actor: Michael Fassbender is coming up fast with an LAFCA win. Why should we care about that group in particular? They're on a six-year roll predicting the Oscar winner for Best Actor. Brad Pitt's also a contender for "Moneyball," getting an art-house bump from "The Tree of Life," with Gary Oldman coming up on the outside thanks to the critical and box-office success of "Tinker, Tailor, Soldier, Spy" and a nod from the San Francisco Film Critics. How about George Clooney for "The Descendants"? He's still in the race, but not at the forefront. Like going for long shots? Then bet Michael Shannon for "Take Shelter," which won NYFCO. And if there's a sweep for "The Artist," add in Jean Dujardin.

Best Actress: Michelle Williams of "My Week With Marilyn," solidifies her spot with a win at the Boston Film Critics Association. Los Angeles went way out for Yung-Jun Hee in "Poetry" (what?) in their 'we're cool and uncorrupted by the Oscar race' vote. NYFCO went classic with Meryl Streep for "The Iron Lady." She's the Streep, but neither she nor Williams will be helped by an apparent lack of enthusiasm for their moves as a whole. Ditto Viola Davis ("The Help"), who will nonetheless make the top five Oscar nominees. Either SF winner Tilda Swinton ("We Need to Talk About Kevin") or multiple-runner-up Kirsten Dunst ("Melancholia") may slip in or come in sixth or seventh. Keep an eye out for Charlize Theron ("Young Adult"), Elizabeth Olsen ("Martha Marcy May Marlene") and Felicity Jones ("Like Crazy) as wild-card entries.

Best Supporting Actor: This is a two-man race between octogenarian Christopher Plummer and Albert Brooks playing against type as a cold-blooded hands-on killer. On the fringes: Patton Oswalt ("Young Adult"), Kenneth Branagh ("My Week with Marilyn") and Andy Serkis ("Rise of the Planet of the Apes").

Best Supporting Actress: Coming up on the inside is Melissa McCarthy for "Bridesmaids." Hurray for comedy! Bolstered by a best ensemble award from the LAFCA, this may push McCarthy into the five Oscar nominees. The LAFCA got behind Jessica Chastain, the NYFCO Breakthrough Performer, who was in every movie from "The Tree of Life" to "The Help," where she'll be competing against her popular co-star Octavia Spencer. The San Francisco critics supported Vanessa Redgrave for "Coriolanus," and Janet McTeer ("Albert Nobbs") was an LAFCA runner up in the category.

Who's out of the running in these five major categories? The Girl With the Dragon Tattoo, War Horse, J. Edgar and Midnight in Paris all underwhelmed. The X-Factor remains Scott Rudin's buzzy "Extremely Loud and Incredibly Close," which has not been screened widely after the New Yorker's David Denby flagrantly broke embargo on Rudin's other major film, "The Girl with the Dragon Tattoo." Pack the Kleenex box for this one.

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Permalink | 記事への反応(0) | 10:27

■Critical Thinking: Film Critics Across the Country Name Their Top Movies and Actors

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Permalink | 記事への反応(0) | 10:27

2011-05-06

■仲が良く皆で話し合える男女混合のグループがステキ→そりゃそうだ！

Evidence for a Collective Intelligence Factor in the Performance of Human Groups
http://www.sciencemag.org/content/330/6004/686.abstract
Psychologists have repeatedly shown that a single statistical factor—often called “general intelligence”—emerges from the correlations among people’s performance on a wide variety of cognitive tasks. But no one has systematically examined whether a similar kind of “collective intelligence” exists for groups of people. In two studies with 699 people, working in groups of two to five, we find converging evidence of a general collective intelligence factor that explains a group’s performance on a wide variety of tasks. This “c factor” is not strongly correlated with the average or maximum individual intelligence of group members but is correlated with the average social sensitivity of group members, the equality in distribution of conversational turn-taking, and the proportion of females in the group.

【適当訳（要つっこみ）】

しばしば「一般的知性」と呼ばれるものの創発が，広範な認知タスクにおける人々のパフォーマンスと相関関係にあると，心理学者たちは繰り返し示してきた．しかし，グループに存在する「集団的知性」と呼ばれるものについて，システマティックに調査したものはいない．699人が2～5人のグループに分かれてタスクを行った二つの実験から，我々はグループのパフォーマンスを説明する一般的な集団的知性の因子の証拠となるものを見つけた．この「c因子」は，グループメンバーの知性の平均や最大とは強い相関はなく，グループメンバーのsocial sensitivity，会話におけるターンテイキングの分布の平等さ，そしてグループ内の女性の割合と相関関係があった．

----

グループパフォーマンスにリーダーシップってのは関係ないのかね．

Permalink | 記事への反応(1) | 19:17

2011-03-14

■【福島 原子力発電所】CNN のコメント欄 MITの科学者 科学者の見解1【東日本 巨大地震】

結論：大丈夫。

MvK2010

I'm going to copy paste a full blog post of a research scientist at MIT here, who explains the situation at Fukushima much better than anyone else has, his message: no worries.

This post is by Dr Josef Oehmen, a research scientist at MIT, in Boston.

He is a PhD Scientist, whose father has extensive experience in Germany’s nuclear industry. I asked him to write this information to my family in Australia, who were being made sick with worry by the media reports coming from Japan. I am republishing it with his permission.

It is a few hours old, so if any information is out of date, blame me for the delay in getting it published.

This is his text in full and unedited. It is very long, so get comfy.

I am writing this text (Mar 12) to give you some peace of mind regarding some of the troubles in Japan, that is the safety of Japan’s nuclear reactors. Up front, the situation is serious, but under control. And this text is long! But you will know more about nuclear power plants after reading it than all journalists on this planet put together.

There was and will *not* be any significant release of radioactivity.

By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.

I have been reading every news release on the incident since the earthquake. There has not been one single (!) report that was accurate and free of errors (and part of that problem is also a weakness in the Japanese crisis communication). By “not free of errors” I do not refer to tendentious anti-nuclear journalism – that is quite normal these days. By “not free of errors” I mean blatant errors regarding physics and natural law, as well as gross misinterpretation of facts, due to an obvious lack of fundamental and basic understanding of the way nuclear reactors are build and operated. I have read a 3 page report on CNN where every single paragraph contained an error.

We will have to cover some fundamentals, before we get into what is going on.

Construction of the Fukushima nuclear power plants

The plants at Fukushima are so called Boiling Water Reactors, or BWR for short. Boiling Water Reactors are similar to a pressure cooker. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water send back to be heated by the nuclear fuel. The pressure cooker operates at about 250 °C.

The nuclear fuel is uranium oxide. Uranium oxide is a ceramic with a very high melting point of about 3000 °C. The fuel is manufactured in pellets (think little cylinders the size of Lego bricks). Those pieces are then put into a long tube made of Zircaloy with a melting point of 2200 °C, and sealed tight. The assembly is called a fuel rod. These fuel rods are then put together to form larger packages, and a number of these packages are then put into the reactor. All these packages together are referred to as “the core”.

The Zircaloy casing is the first containment. It separates the radioactive fuel from the rest of the world.

The core is then placed in the “pressure vessels”. That is the pressure cooker we talked about before. The pressure vessels is the second containment. This is one sturdy piece of a pot, designed to safely contain the core for temperatures several hundred °C. That covers the scenarios where cooling can be restored at some point.

The entire “hardware” of the nuclear reactor – the pressure vessel and all pipes, pumps, coolant (water) reserves, are then encased in the third containment. The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel. The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), which is filled with graphite, all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is built in such a way that the nuclear fuel will be spread out, so it can cool down.

This third containment is then surrounded by the reactor building. The reactor building is an outer shell that is supposed to keep the weather out, but nothing in. (this is the part that was damaged in the explosion, but more to that later).

Fundamentals of nuclear reactions

The uranium fuel generates heat by nuclear fission. Big uranium atoms are split into smaller atoms. That generates heat plus neutrons (one of the particles that forms an atom). When the neutron hits another uranium atom, that splits, generating more neutrons and so on. That is called the nuclear chain reaction.

Now, just packing a lot of fuel rods next to each other would quickly lead to overheating and after about 45 minutes to a melting of the fuel rods. It is worth mentioning at this point that the nuclear fuel in a reactor can *never* cause a nuclear explosion the type of a nuclear bomb. Building a nuclear bomb is actually quite difficult (ask Iran). In Chernobyl, the explosion was caused by excessive pressure buildup, hydrogen explosion and rupture of all containments, propelling molten core material into the environment (a “dirty bomb”). Why that did not and will not happen in Japan, further below.

In order to control the nuclear chain reaction, the reactor operators use so-called “moderator rods”. The moderator rods absorb the neutrons and kill the chain reaction instantaneously. A nuclear reactor is built in such a way, that when operating normally, you take out all the moderator rods. The coolant water then takes away the heat (and converts it into steam and electricity) at the same rate as the core produces it. And you have a lot of leeway around the standard operating point of 250°C.

The challenge is that after inserting the rods and stopping the chain reaction, the core still keeps producing heat. The uranium “stopped” the chain reaction. But a number of intermediate radioactive elements are created by the uranium during its fission process, most notably Cesium and Iodine isotopes, i.e. radioactive versions of these elements that will eventually split up into smaller atoms and not be radioactive anymore. Those elements keep decaying and producing heat. Because they are not regenerated any longer from the uranium (the uranium stopped decaying after the moderator rods were put in), they get less and less, and so the core cools down over a matter of days, until those intermediate radioactive elements are used up.

This residual heat is causing the headaches right now.

So the first “type” of radioactive material is the uranium in the fuel rods, plus the intermediate radioactive elements that the uranium splits into, also inside the fuel rod (Cesium and Iodine).

There is a second type of radioactive material created, outside the fuel rods. The big main difference up front: Those radioactive materials have a very short half-life, that means that they decay very fast and split into non-radioactive materials. By fast I mean seconds. So if these radioactive materials are released into the environment, yes, radioactivity was released, but no, it is not dangerous, at all. Why? By the time you spelled “R-A-D-I-O-N-U-C-L-I-D-E”, they will be harmless, because they will have split up into non radioactive elements. Those radioactive elements are N-16, the radioactive isotope (or version) of nitrogen (air). The others are noble gases such as Xenon. But where do they come from? When the uranium splits, it generates a neutron (see above). Most of these neutrons will hit other uranium atoms and keep the nuclear chain reaction going. But some will leave the fuel rod and hit the water molecules, or the air that is in the water. Then, a non-radioactive element can “capture” the neutron. It becomes radioactive. As described above, it will quickly (seconds) get rid again of the neutron to return to its former beautiful self.

This second “type” of radiation is very important when we talk about the radioactivity being released into the environment later on.

What happened at Fukushima

I will try to summarize the main facts. The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7). So the first hooray for Japanese engineering, everything held up.

When the earthquake hit with 8.9, the nuclear reactors all went into automatic shutdown. Within seconds after the earthquake started, the moderator rods had been inserted into the core and nuclear chain reaction of the uranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normal operating conditions.

The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designing backup systems. The power is needed to keep the coolant pumps working. Since the power plant had been shut down, it cannot produce any electricity by itself any more.

Things were going well for an hour. One set of multiple sets of emergency Diesel power generators kicked in and provided the electricity that was needed. Then the Tsunami came, much bigger than people had expected when building the power plant (see above, factor 7). The tsunami took out all multiple sets of backup Diesel generators.

When designing a nuclear power plant, engineers follow a philosophy called “Defense of Depth”. That means that you first build everything to withstand the worst cat astrophe you can imagine, and then design the plant in such a way that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in one swift strike is such a scenario. The last line of defense is putting everything into the third containment (see above), that will keep everything, whatever the mess, moderator rods in our out, core molten or not, inside the reactor.

http://anond.hatelabo.jp/20110314030613

へ続く

Permalink | 記事への反応(0) | 01:52

2009-11-12

■

科学と生活のイーハトーヴ » 女性の自己実現と、不幸の取り引き

http://blog.ihatovo.com/archives/4816

かいつまんで読んだ解釈ですが、社会進出が進んだといえど、まだ完了していないという実感は根強く残っている。その一方で、働く／家事育児に専念する／両立させる、など選択肢が増えたことによる切り捨てたものへの後悔がもたらす不幸感（選択肢のパラドックス Barry Schwartz: The paradox of choice http://www.t ed.com/index.php/talks/barry_schwartz_on_the_paradox_of_choice.html）も生じているという話題かと。

The Paradox of Declining Female Happiness | MND: Your Daily Dose of Counter-Theory

http://mensnewsdaily.com/2009/09/14/the-paradox-of-declining-female-happiness/

What Women Want Now - The State of the American Woman - TIME

http://www.time.com/time/specials/packages/article/0,28804,1930277_1930145,00.html

CRT/tanaka Blog » Blog Archive » Women, Work and the Happiness Factor

http://blog.crt-tanaka.com/2009/10/women-work-and-the-happiness-factor/

Women’s Declining Happiness: The Paradox That Isn’t « Undecided

http://undecid edthebook.wordpress.com/2009/09/21/womens-declining-happiness-the-paradox-that-isnt/

Op-Ed Columnist - Blue Is the New Black - NYTimes.com

http://www.ny times.com/2009/09/20/opinion/20dowd.html?hp

Permalink | 記事への反応(0) | 07:46

2008-11-16

■[増田BGM]　11. Ex Factor - Lauryn Hill

Ex Factor - Lauryn Hill

夜の増田にふさわしい、しっとりとした曲を選んでみました。

Permalink | 記事への反応(0) | 20:07

2008-07-19

■「ゲーム ジャーナリスト」かあ

http://it.nikkei.co.jp/digital/news/index.aspx?n=MMITew000018072008

個人的な推測だが、スクウェア・エニックスが最終的に決断したのは、コナミが６月に全世界同時発売したＰＳ３独占タイトル「メタルギアソリッド４（ＭＧＳ４）」の販売状況を見てからではないかと思われる。ＭＧＳ４の開発コストは70億円とも噂されており、ＦＦ１３に近い巨大プロジェクトである。

70億円の元ネタってこれだろ？

I heard MGS4 costs 70 million. Which actually sounds ludicrous to me, but in a way it doesn’t if you factor int he MGS4 and MGS online...and the tons of cinematics and long development time...it could get up to that.

これを発言したCory Barlog氏ってのは、ゲーム「ゴッドオブウォー」シリーズのディレクターやってる人で、メタルギアシリーズどころかコナミと関係ない人だろう。同じゲーム業界の人とはいえ、この「噂」を根拠に「それでもワールドワイドでの販売本数としては、開発費を考えれば必ずしも多くはない。」と推測を立てるのはちょっと杜撰じゃないか。あと、

しかし、ＤＶＤ２枚組みにするなど、方法は考えられる。

MGS4がBDの容量(約50GB)ギリギリまで使い切っているというのは、小島秀夫が各種媒体で明言しているんだから「２枚組にするなど」という喩えも無茶がありすぎる。単純計算でも6枚は必要なはずだろうに。

　同社は９月に「インフィニットアンディスカバリー」（Ｘｂｏｘ３６０）、年末に「ラストレムラント」（ＰＳ３、Ｘｂｏｘ３６０）、来年春に「スターオーシャン４」（ＰＳ３、Ｘｂｏｘ３６０）と新しいブランドを投入するが、上位に食い込めるかどうかはわからない。市場の好みが変わってきているからだ。

この点については同感。ただ、スクエニやバンナムが「虎の子」の自社ブランド RPGを「まずはXbox360で」とする体制が、北米市場への参入を意識したものかどうかはちょっと疑わしいと個人的に感じている。
そもそも、記事にもあるようにFPSやオンラインコミュニケーション隆盛な北米で、「クラッシックスタイルＲＰＧ（classic style RPG）」が果たしてどこまで通用するのかは完全に未知数で確かな勝算が見あたらないし、最悪の場合、Xbox360用とPS3用の両版出してもMGS4より売れないというという事態もありうるんじゃないだろうか。MGS4の場合、日本独特のアニメキャラクターではなく、欧米人好みなむさいオッサンが主人公や敵役で数多く登場しつつ、FPS風の遊び方も用意されていたし(仮に360版も出せばもっと売れていただろうというのは同感だけど)。
今回の360傾倒はおそらく、日本市場を主軸にした開発コスト回収が出来なくなったメーカーの方便なんじゃないかと思う。日本メインで売っても儲からないから、アメリカでも売ろう→アメリカは360がメイン→じゃあ360で、といった感じで、コスト回収が先にあって、それを補完するための「北米市場」レトリックなんじゃないかな。日本のメーカーが、日本でよく売れてる(少なくとも過去はそうだったはず)ジャンルのソフトを、日本でもっとも売れていないゲーム機で発売するというのは常識的に見れば異常だもん。個人的感覚では、こういった娯楽商品はまず「地元」でしっかり足固めするべきだと思うんだが、そう判断出来ない事情が色々とあるんだろう。新清士氏がゲームジャーナリストを自称するのであれば、そういった所をえぐり出して欲しかった。

Permalink | 記事への反応(1) | 00:20