Sci-Tech

Better Rubidium Clocks Increase BeiDou Satnav Accuracy

New， ultra-accurate rubidium atomic clocks on board two BeiDou-3 satellites launched into space on November 5 have greatly improved the accuracy of the system.

The two satellites are equipped with more reliable rubidium atomic timekeepers than those in previous BeiDou satellites. According to Yang Changfeng， chief designer of the satellite system， their stability was as high as E-14. “It means only one second of deviation in 3 million years，” he said.

Important payloads of the navigation satellites， atomic clocks are the workhorses which synchronize the signals that allow satnav receivers to triangulate their position on Earth.

“The stability of the new-generation clocks has been improved tenfold， compared with those carried by BeiDou-2 satellites，” said Qu Yongsheng， developer of the clocks from the Xian branch of the China Aerospace Science and Technology Corporation Fifth Research Institute.

Qu said this new technology has raised the positioning accuracy of the BeiDou-3 to 2.5 - 5 meters from 10 meters in the past.

Named after the Chinese term for the Big Dipper constellation， the BeiDou project was formally initiated in 1994， began to serve China in 2000， and was expanded across the Asia-Pacific region at the end of 2012.

BeiDou is intended to become a global positioning and navigation system by around 2020.

Advanced Version of Chinas First Electric Plane Makes Maiden Flight

An advanced version of Chinas first electric plane made its maiden flight on November 1， extending the single flight time from 45 minutes to two hours.

The two-seater aircraft， the RX1E-A， designed by Shenyang Aerospace University， performed the feat at Caihu airport in Shenyang， the capital of northeast Chinas Liaoning Province.

The extended endurance of the plane will help it tap into markets in the United States and Europe， according to Zou Haining， deputy head of Liaoning General Aviation Academy.

In addition， the improved aircraft is equipped with a new parachute that enables safe landing for both the pilot and plane.

With a maximum speed of 160 km per hour， a maximum elevation altitude of 3，000 meters， and a maximum take-off weight of 600 kg， the aircraft can be used in pilot training， passenger transportation， tourism， and aerial photography.

Chinese Scientists Complete Genome Sequencing for Coconutendprint

Chinese scientists announced on November 2 that they had completed sequencing the genome of the coconut.

Scientists from the Chinese Academy of Tropical Agricultural Sciences sequenced and assembled the genome of the coconut， laying solid foundations for further research of functional genes of the coconut and Palmae family.

A genome is the full complement of an organisms DNA– complex molecules that direct the formation and function of all living organisms. The size of an organisms genome is measured by the number of bases it contains – base pairs being the building blocks of DNA.

“We found 282 unique genome families in the coconut，”said Yang Yaodong， a researcher with the academy.

“The completion of the genome sequencing is similar to finishing a drawing of a map of coconut genes，” Yang said.“Following the map， scientists will be able to breed more highyield， drought-enduring， and disease-resistant species， with a shorter breeding cycle.”

Scientists began the genome sequencing project more than four years ago. The research paper was published in Giga Science journal.

China Develops Self-driving Electric City Buses

A new model of selfdriving city bus， the first to be solely electric-powered， has rolled off the production line and finished initial testing at a factory in central Chinas Hubei Province.

The 6.7-meter long bus was jointly developed by Hubei-based auto maker Dongfeng Xiangyang Touring Car Co.， Ltd. and Beijing Institute of Technology， the Hubei provincial economy and information technology commission said on November 6.

After successful testing at the factory， the first two buses have been sent to Shenzhen， Guangdong Province where they will be tested on the road. The buses are expected to be put into use at the end of November， said the commission.

The buses can carry 25 passengers and run at a maximum speed of 40 km per hour. They have the ability to switch between manual driver operation and self-driving.

The new model has energy saving features and boasts high quality parts and manufacturing. A single 40-minute charge allows them to run for up to 150 km. The motor and key parts are expected to last for over 1.2 million km without failure.endprint