Chinese researchers, for the first time, used the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the world’s largest single-dish and most sensitive radio telescope developed by China, to detect the extreme turbulence of plasma in the dense binary system, providing new clues to the eclipse mechanism of the “Black Widow” pulsars (BWPs), the Science and Technology Daily reported on Monday.
The study, led by researchers from China and the Western Sydney University, was published in the monthly journal of the Royal Astronomical Society, a professional academic journal of international astronomy
What are ‘Black Widow’ pulsars?
Millisecond pulsars are categorized as fast-spinning neutron stars and their rotation period lasts only for a few milliseconds.
The BWPs are named by astronomers as a special type of millisecond pulsars with dense binary system consisting of millisecond pulsar and a low-mass star, especially for the companion star is being cannibalized by the pulsars’ intense radiation.
Zhi Qijun, dean of the Physics and Electronics School of Science of Guizhou Normal University, also director of the Guizhou Provincial Key Laboratory of Radio Astronomy Data Processing, said, “many BWPs have been observed with mysterious radio signal eclipses, which are generally thought to be caused by orbiting plasmas that interfere with the propagation of radio radiation.”
Nonetheless, the nature of this plasma is still unclear, Zhi added, noting that the lack of clarity is mainly due to the previous installed radio telescopes, especially those in the mid- and high-frequency bands, which lack sensitivity.
How FAST helps to pursuit new findings?
Thanks to FAST’s ultra-high sensitivity, researchers finally detected the scattering of radio pulses near the occultation region of the BWPs B1957+20 for the first time.
The deeper they detected into the eclipse center, the wider and stronger the radio pulse profile radiated by the pulsar became, with a maximum rotation period of 0.2 milliseconds.
The observations provide the first evidence of strong scattering due to multipath propagation effects in the eclipsing material, with results showing that the eclipsing material in such systems can be highly turbulent and scattering is one of the main eclipsing mechanisms at around high-frequency (1.4 GHz) radio radiation.
In addition, researchers also stated that these findings will have important implications for the origin of the pulse broadening observed in fast radio bursts (FRBs).
China’s first bio-aviation kerosene producer trials clean energy production
China’s leading oil producer Sinopec announced the country’s first successful trial production of bio-aviation kerosene on Tuesday, marking China’s solid step towards large-scale commercial production of aviation biofuel.
The first trial production, conducted by Sinopec Zhenhai Refining and Chemical Company, generated around 606 tonnes of bio-aviation kerosene, part of which will be supplied to airline companies.
Bio-aviation kerosene is produced from renewable resources such as waste cooking oil and animal and plant fat. Compared with traditional petroleum-based aviation fuel, the new biofuel can reduce CO2 emissions by over 50 percent or more throughout an airplane’s service cycle.
Self-developed high-tech project
In 2009, Sinopec started to conduct research on bio-aviation kerosene. It obtained China’s first bio-aviation kerosene airworthiness certificate in 2014, making it the first country in Asia and the fourth country in the world to have self-developed bio-aviation kerosene technology.
In August 2020, China built its first large-scale industrial plant for producing bio-aviation kerosene with a designed annual capacity of processing around 100,000 tonnes.
Huang Aibin, director of the Sinopec Zhenhai Refining and Chemical Company, told China Media Group (CMG) that “the amount of waste cooking oil recycled in a city with a 10 million population is about 10,000 tonnes per month. If runs at full capacity, this plant can almost digest all the recycled gutter oil of a city this size annually.”
Huang also mentioned the biggest difficulty is handling gutter oil as it contains a large number of fatty acid compounds, sulfur, chlorine, metal elements and other impurities, which are extremely difficult to remove. Huang’s team independently developed a special catalyst to optimize the processes of mixing, catalysis and heating.
According to data, if China replaces its current aviation kerosene of around 30 million tonnes aviation kerosene with biofuel, the country can reduce about 55 million tonnes of carbon dioxide emissions annually, which is equivalent to dropping driving over 30 million family economic cars for a whole year.
China launches 1st 2,000-tonne offshore wind farm installation vessel
Baihetan, China’s first 2,000-tonne offshore wind farm installation vessel, was launched on Wednesday in Guangzhou, south China’s Guangdong Province.
Built by China Three Gorges Corporation, the 126-meter-long, 50-meter-wide vessel has a full load displacement of 37,000 tonnes and integrates functions such as transport, self-elevation, self-propulsion, lifting and dynamic positioning.
With a maximum variable load of 6,500 tonnes and a deck area of 4,200 square meters, the vessel can be used for the installation of offshore wind turbines of up to 15 megawatts.
The vessel is able to lift goods as heavy as 2,000 tonnes and work underwater as deep as 70 meters, which greatly enhances the country’s construction and installation capacity in offshore deep-water and off-lying sea areas.
The construction of the vessel started in July 2021. It is expected to be delivered and put into operation within this year, and will be mainly operated in Guangdong and Fujian provinces, according to the company.
China’s new telecom carrier launches 5G services
China Broadnet, China’s fourth telecommunication operator, has formally launched 5G services.
The launch event held at the Museum of the Communist Party of China (CPC) was attended by Huang Kunming, a member of the Political Bureau of the CPC Central Committee and head of the Publicity Department of the CPC Central Committee.
The official website of China Broadnet, www.10099.com.cn, opened to the public on the same day. People can order new China Broadnet SIM cards on the site. The phone number will start with 192.
The website said the current commercial 5G service is still in the test phase, which means problems may occur to users, and the company won’t take responsibility for the consequences. The end date of the test phase has not been announced yet.
The company’s mobile service starts at 38 yuan (about $6) monthly, with 10 gigabytes of data and 50 minutes of voice calling, and goes as high as 588 yuan (about $88) with 398 GB data and 1,600 minutes of voice calling.
At this price, China Broadnet appears more cost-effective than China Mobile. But the established three carriers all offer many discounts to attract users.
The number in the website’s domain name, 10099, is also the company’s service phone number, which now provides 5G-related services.
No information about home broadband service can be found of the website as of Monday afternoon.
The service launch marks a breakthrough in the integration of national cable TV networks, and 5G integrated development and early successes in developing a new “cable plus 5G” integrated development paradigm for China’s radio and TV networks.
A key advantage of China Broadnet’s 5G is the 700 megahertz signal, which is better than the other three carriers’ services in signal strength.
Yet, the company has to build many base stations to cover the whole country. China Broadnet is cooperating with China Mobile to share base stations.
Also, the lower signal frequency will limit the max speed of China Broadnet’s 5G, which may not have a big impact on users’ choices since even 4G speed can satisfy most users for now.
With the 5G services’ launch, China Broadnet vows to speed up the development of a new-type radio and TV communication network, a national cultural network, and a national, new-type infrastructure network.
The company has rebranded as its current name and launched phone number reservations in early June.
China Broadnet was granted a 5G license for commercial use in 2019.
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