Aizhai Bridge: the highest suspension bridge in world opens to traffic
Aizhai Bridge: the highest suspension bridge in world opens to traffic | China's Great Science and Technology
On March 31, 2012. Aizhai suspension bridge, with a main span of 1,176 meters and a maximum height of 330 meters, was open to traffic on Saturday. Spanning over the Dehang canyon, the bridge was built as part of the expressway from southwest China’s Chongqing Municipality to Changsha city in Hunan. Its completion would greatly improve the transportation between the two cities, according to authorities.
On the Morning of March 28 2010, the haulage cable has been successfully pulled from the Chadong Section to the Jishou Section on the opposite side of Dehang Grand Gorge by helium airship, which means the Aizhai Grand Suspension Bridge of the Jicha Highway has entered its main cable construction stage.
On 09:08 am, having flied across the 1,176-meter gorge, the airship reached the other side successfully 17 minutes later and made a connection between the two sides by a high-strength nylon rope with a diameter of millimeters.
According to the project director, the Aizhai Grand Suspension Bridge is a key project in the whole Jicha Highway program. With a main span of 1,176 meters and a subgrade width of 24.5 meters, this steel truss suspension bridge has the largest span in gorge throughout our country. The bridge is to be build in accordance with the highway standard of two lanes & four driveways, whose designed speed is 80 kilometers per hour As the bridge is located 335 meters over the Aizhai Town and the traffic below the bridge is heavy, it is proved that pulling the haulage cable by an airship would be the most convenient and safest way to start the project.
When it opens in 2012, Aizhai will be the world’s highest tunnel to tunnel bridge and the fourth suspension bridge in China to cross a valley so wide it seems to be connecting two mountain ranges. The first three were the Siduhe, Balinghe and Beipanjiang 2009 bridges. Of the world’s 400 or so highest bridges, none will have a main span as long as Aizhai with a tower to tower distance of 3,858 feet (1,176 mtrs). Located deep in the heart of China’s Hunan Province near the city of Jishou, the suspension bridge is the largest structure on the Jishou to Chadong expressway with a deck 1,083 feet (330 mtrs) above the DeHang Canyon.
The bridge in morning
The two tunnels on either side of the Aizhai bridge allowed the engineers to use the mountain top for the location of one of the towers, reducing its height to just 165 feet (50 mtrs) – unusually short for a bridge with a span nearly as long as the Golden Gate bridge at 3,858 feet (1176 mtrs). In addition to cost savings, the stubby support also allows the bridge to blend more naturally into its surroundings. The taller bridge tower is no less unique with side span cables that soar down the backside of a mountain, making first time visitors quizzical as to what exactly lies ahead. With most of the structure hidden from view, the bridge will come as a jaw-dropping surprise whether you enter the canyon from either tunnel. Due to a gap of approximately 328 feet (100 mtrs) between the last truss suspenders and the tops of the bridge towers, the engineers added some additional ground anchored suspenders to stabilize the two massive suspension cables and reduce any oscillations that could damage other components of the bridge. An overlook and visitors center will offer additional views of the broad valley.
Asia’s largest rotating radio telescope to be completed in Sheshan, Shanghai
Asia’s largest rotating radio telescope to be completed in Sheshan, Shanghai | China's Great Science and Technology
Sheshan in Shanghai will build Asia’s largest rotating radio telescope at the caliber of 65 meters. It will be completed in 2012 as the largest rotatable radio telescope in Asia, only next to the 110m-diameter telescope based in the United States and the 110m-diameter telescope based in Germany.
The Shanghai Astronomical Observatory was funded in 2008 by the Chinese Academy of Sciences and the Science and Technology Commission of Shanghai Municipality to build a 65 meter radio telescope for both space-related and radio astronomical observations. The project was supported by the Shanghai government to locate the telescope at Shanghai Sheshan area, in the same region the first Chinese VLBI station of a 25 meter in diameter radio telescope was constructed in 1987.
The Shanghai 65 meter radio telescope is designed to be a general purpose, fully steerable antenna. It will have a main reflector of 65 meter in diameter in a shaped Cassegrain configuration with a primary focal ratio of 0.32. The primary active surface control system will be installed to compensate (mainly) the repeatable gravitational deformations to maintain the nominal shape of the primary reflector, and then to reach the best performance even at high frequencies. The main structural constraints for the antenna design are the surface accuracy and the pointing accuracy. The primary reflector consists of a total of 1008 aluminum panels in 14 rings, and at its back about 1112 electromechanical actuators will be mounted at each corner of four adjacent panels. A custom actuator design is now under way. The telescope is currently designed to operate to 15 GHz without use of the active surface system. The antenna will be equipped with receivers to cover 8 frequency bands from 1.4 GHz to 43 GHz, including L-, S-, C-, X-, Ku-, K-, Ka-, and Q-band. Among those, both S/X and X/Ka are dual-frequency bands. The Shanghai 65 meter radio telescope now is in its full construction phase.
The new radio telescope will find application in deep space exploration missions and basic astronomy research. It will also be used in China’s lunar exploration program as an important part of China’s Very Long Baseline Interferometry (VLBI) array system of radio telescopes.
Currently, the VLBI network in China is composed of four telescopes in shanghai, Beijing, Kunming and Urumqi.
The VLBI successfully carried out orbit determination and positioning in the launching of the lunar obitor Chang’e -1. The 65m-diameter telescope will guide the lunar rover’s way to the moon together with other VLBI telescopes when the second phase of the country’s lunar exploration program is carried out in 2012.
“We have been making efforts in the past 30 years to develop VLBI technology, and contribute to the international astronomic research,” said Shen Zhiqiang, a research professor with the observatory. “We are proud that the technology was used in the lunar exploration.”
The telescope will also be included in the East Asia VLBI consortium which consists of 19 radio telescopes so far from China, Japan and the Republic of Korea (ROK).
Meanwhile, astronomical observatories from China, Japan and South Korea will increase cooperation to build the current radio telescope network to East Asia’s VLBI observational network, which will be in service in 2010 with the largest number of telescopes.
China has built World’s Largest Tracking Solar Power Station in Ningxia
China has built World’s Largest Tracking Solar Power Station in Ningxia | China's Great Science and Technology
China ENFI Engineering Corp. (ENFI) announced that, ENFI Ningxia Zhongwei Tianjingshan 30MW Photovoltaic Power Works, which was under full-process planning, investment, construction and operation by ENFI, was successfully combined to the grid and put into commissioning on December 22, 2011.
As a tracking solar photovoltaic power station with the maximum installed capacity at the present in the whole world, it is fully equipped with the intelligent linkage tracking system which is independently developed by ENFI. This system is featured by accurate solar tracking device and stable power generation indicators, which will greatly enhance the volume and quality of photovoltaic power generation and will be easily combined to the grid and operated. Comparing with the traditional solar photovoltaic power station, it will contribute an increase of about 25% in power output and the annual average generated energy will be up to 54 million KWH. On this ground, a total increase of 270 million KWH during the 25-year operation period.
This project is contracted by ENFI on an EPC basis. The construction works under the first phase (10MW) was formally commenced in March 2011 and completed in August in this year; the second phase (20MW) was started in October 2011, and completion acceptance as fulfilled in November 2011, marking a new record in terms of the construction speed of solar photovoltaic power station. In addition, the commissioning and grid connection works for the 30MW solar photovoltaic power station was successfully finished at one go-off, enabling the facility to generate benefit in the same year of construction. Taking advantage of technical R&D, fine design and scientific management, ENFI has stepped onto a new level in terms of the scientific technology and the power generation efficiency in this industry. As a matter of fact, a saving of 20% was realized on the investment costs and a satisfactory EPC benefit was eventually achieved.
Under this project, solar energy is utilized for power generation in a zero-emission manner, which will reduce the same volume of conventional thermal power supplied for the national grid, thus the annual average emission deduction of carbon dioxide will be 51,500 tons, and a total reduction of 1.3 million tons will be realized during the 25-year operational period. Comparing with the traditional thermal power works, the implementation of this project will bring about more favorable results such as: (i) coal saving for coal-fired power station; (ii) reduction of greenhouse gas emission; (iii) increasing of power supply and CDM (Clean Development Mechanism) achievements; and (iv) bringing about perfect economic benefits and long-lasting environmental benefits.