期刊文献+
共找到4篇文章
< 1 >
每页显示 20 50 100
A History of the Urban Underground Tunnel (4000 B.C.E. - 1900 C.E.)
1
作者 Robert Steven Diamond Brian Garret Kassel 《Journal of Transportation Technologies》 2018年第1期11-43,共33页
Generally hidden from public view, out of our daily thoughts, and literally under our feet, are myriad urban underground tunnels that make our modern megacities possible. From their ancient beginnings in antiquity, as... Generally hidden from public view, out of our daily thoughts, and literally under our feet, are myriad urban underground tunnels that make our modern megacities possible. From their ancient beginnings in antiquity, as a means of supplying fresh water and draining waste water from cities, underground tunnels evolved into a means of providing high capacity rail mass transit in our most densely populated urban centers. This paper provides a broad overview of the evolution of urban tunnels across a 6000 year time span and includes the specific engineering formulas/computations for the earliest 19th century subways/infrastructure projects based on the Roman vaulted arch tunnel. 展开更多
关键词 Subway SUBTERRANEAN passageway Ancient Underground MESOPOTAMIA Greece Rome Cut and Cover CLOACA Maxima Cryptoporticus CROtoN Aq-ueduct Arch TUNNEL Atlantic Avenue TUNNEL LONDON Railway LONDON Tube Beach/Greathead Shield 19th Century Arched TUNNEL Calculations
下载PDF
Theoretical and numerical analysis of coal dust separated by centrifugal force for working and heading faces 被引量:7
2
作者 Shiqiang Chen Haiqiao Wang +3 位作者 Yiqun Li Haijiao Cui Jie Zhao Xiaowei Zhang 《International Journal of Coal Science & Technology》 EI CAS 2014年第3期338-345,共8页
In order to meet engineering needs of Chinese underground coal mines,a new dust-collecting fan,a device of dust separated by centrifugal force in driven cyclone passageway(DCCP)was designed.In centrifugal dust removal... In order to meet engineering needs of Chinese underground coal mines,a new dust-collecting fan,a device of dust separated by centrifugal force in driven cyclone passageway(DCCP)was designed.In centrifugal dust removal section(CDRS)of DCCP,a general equation is derived from the principle of force equilibrium.According to CDRS structure parameters and fan running parameters,the general equation is simplified,and the simplest equation is calculated numerically by MATLAB.The calculation results illustrate that increasing quantity of air current is against dust removal,but it is beneficial to dust removal by increasing the radius of driven spiral blade and increasing the particle diameter of coal dust.The conclusions show that the dust-collecting structure parameters coupled with the fan running parameters is a novel optimization approach to dust-collection fan for working and heading faces,which is especially suitable for Chinese underground mines. 展开更多
关键词 Working and heading faces Coal dust removal Centrifugal separation-Driven spiral passageway
下载PDF
Numerical analysis of water inrush from working-face floor during mining 被引量:21
3
作者 ZHU Qing-hua FENG Mei-mei MAO Xian-biao 《Journal of China University of Mining and Technology》 EI 2008年第2期159-163,共5页
Confined water in the Ordovician limestone is one of the hidden troubles that threaten safe production of mines in north China. A numerical model of the key strata was developed. It included the structural characteris... Confined water in the Ordovician limestone is one of the hidden troubles that threaten safe production of mines in north China. A numerical model of the key strata was developed. It included the structural characteristics and mechanical properties of the floor rock at the working face of a particular coal mine. The model was used to predict failure modes and to help establish rules for safe mining above the aquifer. The distribution of deformation, failure and seepage was simulated by using Dilian Mechsoft's Real- istic Failure Process Analysis (RFPA2D) program. The stress distribution, the deformation and the flow vectors were also obtained. The results indicate that: 1) The original balance of the stress and seepage fields is disturbed due to coal mining; and 2) As the working face advances different deformation, or failure, appears in the surrounding rocks, the water-resisting strata in floor may be destroyed and the passage of water from the aquifer into the mine may occur. The combined action of mining stress and water pressure ultimately lead to water inrush from the floor. 展开更多
关键词 water inrush from floor stress field seepage field passageway of water-transmit numerical simulation
下载PDF
Circle Points Discharge Tube Current Controller
4
作者 蒙晋佳 蒙里声 《Plasma Science and Technology》 SCIE EI CAS CSCD 2005年第3期2868-2871,共4页
Circle points discharge tube current controller is a new type device to limit the output of high voltage discharge current. Circle points uniform corona discharge to form air ionization current in the discharge tube. ... Circle points discharge tube current controller is a new type device to limit the output of high voltage discharge current. Circle points uniform corona discharge to form air ionization current in the discharge tube. On the outside, even if the discharge electrode is spark discharging or the two discharge electrodes are short circuited, the air ionization current in the tube remains within a stable range, and there is no spark discharge. In this case, when the discharge current only increases slightly, the requirement to limited current is obtained. By installing the controller at a discharge pole with a small power but high voltage supply, we can realize the shift between the continuous spark line discharge and corona discharge. This provides a new simple device for spark discharge research and is a supplement to the Townsend discharge experiment. 展开更多
关键词 spark line discharge corona discharge discharge current passageway density threshold level of spark discharge
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部