19th Century Math Tactic Gets a Makeover—and Yields Answers Up to 200 Times Faster


Simulation data showing significantly faster reduction in solution error for the new Scheduled Relaxation Jacobi (SRJ) method as compared to the classical Jacobi and Gauss-Seidel iterative methods.The equation that is being solved here is the two-dimensional Laplace equation on a 128×128 grid.

A relic from long before the age of supercomputers, the 169-year-old math strategy called the Jacobi iterative method is widely dismissed today as too slow to be useful. But thanks to a curious, numbers-savvy Johns Hopkins engineering student and his professor, it may soon get a new lease on life.

With just a few modern-day tweaks, the researchers say they’ve made the rarely used Jacobi method work up to 200 times faster. The result, they say, could speed up the performance of computer simulations used in aerospace design, shipbuilding, weather and climate modeling, biomechanics and other engineering tasks.

Their paper describing this updated math tool was published June 27 in the online edition of the Journal of Computational Physics. Continue reading “19th Century Math Tactic Gets a Makeover—and Yields Answers Up to 200 Times Faster”

China accuses Japan of interfering in naval drills

Nov. 01, 2013 – 06:17AM JST

BEIJING —

China’s Defense Ministry said on Thursday it has lodged a formal diplomatic complaint over what it called “dangerous provocation” by Japan for shadowing Chinese military exercises in the western Pacific.

Sino-Japanese ties have been strained for months by a dispute over tiny islands in the East China Sea believed to be surrounded by energy-rich waters. They have also been overshadowed by what China says is Japan’s refusal to admit to atrocities committed by Japanese soldiers in China between 1931 and 1945.

Defense Ministry spokesman Yang Yujun said that a Japanese naval and air patrol disrupted a Chinese live ammunition military drill last Friday, without giving the precise location.

Yang also said Japanese patrols of ships and aircraft were gathering information about the exercises.

“Not only did this interfere with our normal exercises, but endangered the safety of our ships and aircraft, which could have led to a miscalculation or mishap or other sudden incident,” Yang told a news briefing.

“This is a highly dangerous provocation, and China’s Defense Ministry has made solemn representations to the Japanese side,” he added, according to a transcript of his remarks on the ministry’s website.

Diplomatic complaints are normally lodged by the Foreign Ministry, so the Defense Ministry’s unusual move signals the military’s anger.

A former Japanese military officer told Reuters this week that the situation in the East China Sea was worrisome.

“As the Chinese are getting more active, we have more opportunities to confront each other,” he said. “If something happens accidentally, it may very seriously deteriorate the bilateral relationship.”

Ties between the two countries took a hit in September 2012 after Japan bought two of the disputed islets from a private owner, setting off a wave of protests and boycotts of Japanese goods across China.

China on Saturday criticised a Japanese media report saying Prime Minister Shinzo Abe had approved a policy for Japan to shoot down foreign drones that ignore warnings to exit its airspace.

Abe has said Japan is ready to take a more assertive stance toward China.

(c) Copyright Thomson Reuters 2013.

 

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Teenager becomes first victim of China’s new ‘anti-gossip’ law after blog

  • Boy publicly questioned police  investigation into death of local businessman
  • Internet censors have ordered bloggers to  ‘keep social order’

By  Anna Edwards

PUBLISHED: 04:16 EST, 20  September 2013 |  UPDATED: 06:07 EST, 20 September 2013

 

A draconian measure to stop people  ‘gossiping’ online in China has claimed its first ‘offender’ – a 16-year-old  boy.

The country has imposed strict limits on what  people can and cannot say on the internet, which many thought would target  whistleblowers, critics of the government, or activists.

Instead, a teenager, named only as Yang, was  arrested for ‘provoking trouble’ by criticising police online.

In August, internet censors called popular bloggers to meetings and asked them to agree to standards, including keeping social order  

In August, internet censors called popular bloggers to  meetings and asked them to agree to standards, including keeping social order

 

The Beijing Times has interviewed a man, who  claims police took his 16-year-old son away this week, after accusing him of  ‘picking quarrels and provoking trouble’.

The newspaper said the blogger had gone on  the popular social media site Weibo to post his criticisms of the police  handling of a death in the community.

A statement from authorities in  Zhangjiachuan, Gansu province said the boy had publicly questioned a police  investigation about the death of a local businessman, the Daily Telegraph  reported.

The case involved a karaoke bar manager who  supposedly committed suicide by leaping from a building.

But the sceptical teenager posted the claim  that the man had been beaten up in a row, and accused the police of failing to  investigate fully.

State media have also accused some microbloggers of undermining socialism and promoting Western values  

State media have also accused some microbloggers of  undermining socialism and promoting Western values

His accusation quickly went viral and caught  the attention of the authorities, who decided to act.

Under the new Chinese law it is illegal to  post ‘false information’ that may be harmful to others.

The law stipulates that if such information  is retweeted 500 times or seen by 5000 users, the person who posted it can be  arrested.

In August, internet censors summoned popular  micro-bloggers to meetings and asked them to agree to standards, including  keeping social order – a move observers have said has a chilling effect on  public discourse.

State media have also accused some  micro-bloggers of undermining socialism and promoting Western values by  spreading lies and negative news.

Last month government-run newspaper The  People’s Daily reminded China’s ‘big Vs’ – popular bloggers whose social media  profiles are verified as genuine – that they ‘should be careful what information  they convey.. and use their right to expression responsibly.’

Many Chinese celebrities, from pop stars to  business tycoons, have amassed huge followings on social media sites, and at  times have posted material that the government has not approved of, such as  calling attention to social injustices and questioning state  policies.

Read more: http://www.dailymail.co.uk/news/article-2426559/Chinese-teenager-suggested-police-investigated-mans-death-thoroughly-person-arrested-countrys-new-anti-gossip-law.html#ixzz2fRh0SN7Z Follow us: @MailOnline on Twitter | DailyMail on Facebook

Japan ‘stole’ our islands, Chinese foreign minister tells U.N.

PoliticsSep. 28, 2012 – 11:35AM JST

UNITED NATIONS —

China took a bitter territorial dispute with Japan to the U.N. General Assembly on Thursday, with Foreign Minister Yang Jiechi accusing Tokyo of stealing disputed islands.

The Japanese government’s purchase of the East China Sea islands from a private owner has infuriated the Beijing government and sparked violent protests in several Chinese cities.

“China strongly urges Japan to immediately stop all activities that violate China’s territorial sovereignty, take concrete actions to correct its mistakes and return to the track of resolving the dispute through negotiation,” Yang told the U.N. assembly.

China has demanded the return of the islands, known as the Diaoyu in Chinese and the Senkaku in Japanese, for decades. Yang reaffirmed his country’s historical claim that Japan tricked his country into signing a treaty ceding the islands in 1895.

“The moves taken by Japan are totally illegal and invalid. They can in no way change the historical fact that Japan stole Diaoyu and its affiliated islands from China and the fact that China has territorial sovereignty over them,” said the Chinese minister.

Yang’s speech came two days after stern talks he held with Japan’s Foreign Minister Koichiro Gemba on the dispute.

Japan has repeatedly insisted that the islands come under its control. Taiwan also claims the islands.

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