Beijing, China
Beijing, China

Time filter

Source Type

Yang Y.,CAS Institute of Botany | Lin L.,China Railway Group Ltd | Wang Q.,CAS Institute of Botany
BMC Evolutionary Biology | Year: 2013

Background: The extant Gnetales include three monotypic families, namely, Ephedraceae (Ephedra), Gnetaceae (Gnetum), and Welwitschiaceae (Welwitschia), all of which possess compound female cones that comprise a main axis and 1 to multiple pairs/whorls of bracts subtending a female reproductive unit or having lower pairs/whorls of bracts sterile. However, the evolutionary origin of such a reproductive architecture in Gnetales is controversial in the light of the competing anthophyte versus gnetifer hypotheses of seed plant relationships. Hence, macrofossils demonstrating the structure of compound female cones of the Gnetales should be important to decipher the early evolution of the order. Results: A new ephedroid plant Chengia laxispicata gen. et sp. nov. is described from the Early Cretaceous Yixian Formation of western Liaoning, Northeast China. The fossil represents a part of a leafy shooting system with reproductive organs attached. The main shoot bears internodes and swollen nodes, from which lateral branches arise oppositely. Reproductive organs consist of female spikes terminal to twigs or axillary to linear leaves. Spikes are loosely arranged, having prominent nodes and internodes. Bracts of the spikes are decussately opposite and comprise 4 - 8 pairs of bracts. Each bract subtends an ellipsoid seed. Seeds are sessile, with a thin outer envelope and a distal micropylar tube. Conclusions: Chengia laxispicata gen. et sp. nov. provides a missing link between archetypal fertile organs in the crown lineage of the Gnetales and compound female cones of the extant Ephedraceae. Combined with a wealth of Ephedra and ephedroid macrofossils from the Early Cretaceous, we propose a reduction and sterilization hypothesis that the female cone of the extant Ephedraceae may have stemmed from archetypal fertile organs in the crown lineage of the Gnetales. These have undergone sequentially intermediate links similar to female cones of Cretaceous Siphonospermum, Chengia, and Liaoxia by reduction and sterilization of the lower fertile bracts, shortenings of internodes and peduncles as well as loss of reproductive units in all inferior bracts. The basal family Ephedraceae including Ephedra of the extant Gnetales was demonstrated to have considerable diversity by the Early Cretaceous, so an emended familial diagnosis is given here. The Jehol Biota in Northeast China and adjacent areas contains a plethora of well-preserved macrofossils of Ephedra and ephedroids that show different evolutionary stages including primitive and derived characters of Ephedraceae, so Northeast China and adjacent areas may represent either the centre of origination or one of the centres for early diversification of the family. © 2013 Yang et al.; licensee BioMed Central Ltd.


Ma S.,Southwest Research Institute | Han X.,China Railway Group Ltd | Liao K.,Southwest Research Institute
Modern Tunnelling Technology | Year: 2014

In order to reduce collapse damage to tunnels, based on the example of engineering in a shallow loess tunnel with a large section, the method of real-time monitoring of and early alarms for tunnel collapse is put forward. The principles of establishing early-alarm benchmark values and standards for early-alarm grading are presented, and an early-alarm system for tunnel collapse prevention (both hardware and software) is developed and tested on site. Testing results show that the hardware and software are reliable and adaptable to complex tunnel construction environments, the acquisition and transmission of data from the testing instruments performs normally, and the software system data vary with the real-time monitoring data, resulting in a grading of alarms.


Meng X.-H.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2015

Research purposes: In order to meet the requirement of the construction of Harbin-Dalian High Speed Railway, further improve the efficiency of the railway transportation and shorten the running time, 60 kg/m-62# high-speed turnout with speed 350 km/hour is designed out which makes the side allowable speed of turnout achieve 220 km/h. This paper mainly illustrates the critical manufacturing technology and frog assembling and turnout laying technology, to improve the technology of our big size turnout. Research conclusions: (1)In the producing process of the steel rails that slenderness ratio is 2168, the deformation is controlled, which plays a crucial role in successful trial-production of turnout. (2)The processing quality of the steel rails directly affects the turnout assembly, trial laying and the running state, which is the key of turnout manufacture. (3)The processing technology of the turnout mainly includes processing of steel rails such as switch rails, point rails, wing rails, as well as the plate processing and sulfidizing. (4)The key technology of turnout assembling and laying includes transformation of rail laying assembly platform, determining rail laying assembly benchmark, the initial assembly of rail, rail laying fine adjustment, and so on. (5)The current operation of Harbin-Dalian High Speed Railway shows that the technology of this kind of turnout is advanced enough to achieve the design and high speed running requirements, and is able to be widely used in the high speed railway which the side running speed is 220 km/h. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved.


Li X.-C.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2013

Research purposes: Aiming at the features of the numerous rock variety and large quantities of rock blasting of the Chengdu-Chongqing Highway Project, the research was done the configuration of blasting holes for open-air blasting of the roadbed rock, it was proposed that the equilateral triangular network might be the best configuration of blast holes and a formula was present to illustrate the relation between the hole distance and the diameter of aperture according to the different kinds of rock for providing the reference to the similar works. Research conclusions: (1) The equilateral triangular network is generally used for the configure of the blast holes when the diving drill is adopted for the open-air blasting of the roadbed rock. It has the obvious advantages that the blasted rock blocks are even with the small amount of the under-blasted and over-blasted rocks. (2) The configuration of blast holes and the distance between the hole rows are closely related to the the diameter of aperture. Regarding to the diameters of the rock and drill (diameter of aperture), there is a reasonable range for the distance between the two adjoining hole rows. If the distance of hole configuration exceeds this range, the flying rocks, larger rock blocks and even hopper blasting may happen in blasting. (3) This research result is available for the open-air blasting of the roadbed rock with a good effect.


Li S.-J.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2013

Research purposes: According to the engineering geological and hydrogeological conditions, the specific construction method and supporting parameters were used for the cracked dolomite tunnel in rich-water and high-pressure zone to ensure the construction safety and achieve the reasonable project cost and the best construction progressing for providing the reference to the similar works. Research conclusions: The construction methods of the cracked dolomite tunnel in rich-water and high-pressure zone must be chosen scientifically and flexibly. On the premise of ensuring the structure safety, the construction scheme should be optimized as much as possible to cut the construction cost. In general, the full-face curtain grouting technology should not be used because this technology is complex, the construction progress is slow and the construction cost is high. But the construction progress and the construction cost is fairly reasonableby using the bench cut method. Priority should be given to the bench cut method.


Huang J.-Q.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2013

Research purposes: The subway is a public place that have a large passenger flow and dense population. It is more difficult to manage because of much emergency. In order to improve the security administration within the scope of the public security department of the subway, better service to the subway passengers, a wireless communication command attemper system of public security need to be set up to assure public security communication with subway employees and all departments of the public security bureau. This paper has introduced the development of wireless communication system at home and abroad, has carried on the analysis comparison of several common public security wireless communication system, and puts forward the recommended scheme of various circumstances, It can provide a reference for similar problems that meet in the subway design. Research conclusions: (1) Public security wireless communication system scheme of urban rail transit should be consistent with the urban existing public security wireless communication system, and government affairs wireless communication system of city rail. (2) Centralized way is recommended, which combining the scheme of wired and wireless introduction that wired scheme is given priority to and wireless solutions is standby.(3) At the station platform layer and the underground tunnel, the leakage coaxial cable should be applied to for field coverage. At the station hall layer, the way of ceiling-mounted antenna should be adopted for coverage. (4) Broadband multimedia cluster, such as TD-LTE with independent intellectual property, is the future development direction of public security wireless communication system in our country.


Li Q.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2015

Research purposes: Currently, the global mining resources industry is experiencing a declining period since 2000|, due to the decline of the global macro economy. It creates a historic opportunity for Chinese enterprises to participate in overseas mining investment. However, neither the execution of overseas investment nor the investment result is satisfying. After deepen understanding of the international mining market and summary of the experiences, Chinese enterprises create several new investment models by constant practice during recent years. This paper focuses on the problems of traditional investment model and orientation of the model innovation by analyzing the current situation of Chinese enterprises overseas mining investment and the practical cases. Research conclusions: (1) Chinese enterprises have various problems, such as negative effects on investment results or program progress, by using traditional mining investment models. (2) The investment model innovation is beneficial to diversify investment risks and protect investment income. (3) Chinese enterprises should actively practice new investment model with its own operation characteristics and advantages on industry or investment experience. (4) This research results can provide references for similar enterprises to execute overseas mining investment. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved.


Lu W.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2014

Research conclusions: (1) The main reasons for the four-corner seams of CRTS-I ballastless track slab are the buckling deformation caused by the temperature difference between the board and the bottom and the Hanging Empty phenomenon between lower and higher tracks among adjacent slabs after track-laying. (2) The night or the season of least temperature difference between day and night would be better to do mortar pouring, and the best time is between 21:00 and 6:30. Also delicate adjustment, effective clamping force and full mortar pouring are necessary. (3) It is also necessary to improve the adjustment accuracy of the slabs, especially to maximize to eliminate the height difference of adjacent tracks. (4) This study is very useful to reduce the seams of CRTSI, II, III ballastless track slab's four corners.Research purposes: Given the actual condition of the seams' regular change in four corners between CRTS-I ballastless track slab of Harbin-Dalian Passenger Dedicated Line and mortar of packed layer in severe cold area, in order to reduce or eliminate the influence for ballastless track structure from the four-corner seams, this dissertation discusses the causes of the four-corner seams of CRTS-I ballastless track slab in theory and offers solutions for reference of design and construction of slab ballastless track structure in China.


Huang J.-Q.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2014

Research purposes: With the rapid development of urban rail transit construction in our country, the passenger demand for information system also is increasing day by day, the deep industrial upgrading of the rail transit industry is driving industry wireless private network to broadband networks, which need to support real-time mobile broadband access under the condition of high-speed. With the characteristics of wide range, high bandwidth, a number of concurrent users, strong anti-jamming capability, safe and reliable, LTE is becoming the choice of wireless private network of rail transit industry to develop new technologies. Through the analysis and study of the application of LTE in wireless transmission of subway passenger information system, this paper can provide the reference for the similar problems in the subway design and construction.Research conclusions: Through the study, it is concluded that: (1) Suggest that the wireless network subsystem of the subway passenger information system is made of TD-LTE technology, the frequency of use is 1 795~1 805 MHZ. System is made of switching equipment setting up in the control center, baseband equipment (BBU) setting up at the station, remote device (RRU) and road equipment setting up in the interval, car wireless devices and transmitting antenna and optical cable laying in interval tunnel, etc. (2) The long distance underground tunnel is recommended to use RRU cascade to extend coverage. Suggest system adopt community merging method, reduce the number of community, and reduce the number of switch. (3) The proposed system solutions offer the reference for the future wireless network design in urban rail transit. ©, 2014, Journal of Railway Engineering Society. All right reserved.


Yuan M.,China Railway Group Ltd
Journal of Railway Engineering Society | Year: 2015

Research purposes: For the purpose of ensuring the safe operation of large tonnage transport and erection equipment in high speed railway construction, a specific remote system based on modern information technology is developed, which implements remote, high speed and multidirectional interconnection of equipment group, provides a new mode of monitoring and managing the safety of high speed railway construction involving large tonnage (more than 900t)transport and erection equipment. Research conclusions: (1) It is in accordance with the trend of informatization of large construction equipment to improve safety monitoring & management in the remote system through modern information technology. (2) The remote system can improve the timeliness and reliability of making decision through effective communication and management. (3) The remote system can ensure a high speed railway project be successful when it is completed in terms of safety, effectiveness, time and cost. (4) The remote system can provide very useful experience for reference in terms of the safe operation of railway construction equipment and highway construction equipment. ©, 2015, Editorial Department of Journal of Railway Engineering Society. All right reserved.

Loading China Railway Group Ltd collaborators
Loading China Railway Group Ltd collaborators