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Effect of temperature difference load of 32 m simply supported box beam bridge on track vertical irregularity 被引量:5
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作者 Kaize Xie Jun Xing +3 位作者 Li Wang Chunxiang Tian Rong Chen Ping Wang 《Journal of Modern Transportation》 2015年第4期262-271,共10页
In order to study the effect of temperature difference load (TDL) along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was establ... In order to study the effect of temperature difference load (TDL) along the vertical direction of a simply supported beam bridge section on the vertical irregularity, a rail-bridge-piers calculation model was established. Taking 32 m simply supported box beam bridge which is widely used in the construction of pas- senger dedicated line in China as an example, influences of the temperature variation between the bottom and top of the bridge, temperature curve index, type of temperature gradient, and beam height on track vertical irregularity were analyzed with the model. The results show that TDL has more effects on long wave track irregularity than on short one, and the wavelength mainly affected is approxi- mately equal to the beam span. The amplitude of irregu- larity caused by TDL is largely affected by the temperature variation, temperature curve index, and type of temperature gradient, so it is necessary to monitor the temperaturedistribution of bridges in different regions to provide accurate calculation parameters. In order to avoid the irregularity exceeding the limit values, the height of 32, 48, and 64 m simply supported box beam bridges must not be less than 2.15, 3.2, and 4.05 m, respectively. 展开更多
关键词 Simply supported beam bridge Temperaturegradient vertical irregularity - beam height
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HYDROSTATIC PRESSURE CALCULATION AND OPTIMIZATION FOR DESIGN OF BEAM & SLIDE-REST GUIDEWAYS IN HEAVY DUTY CNC VERTICAL TURNING MILL 被引量:4
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作者 ZHAO Ming HUANG Zhengdong LI Bin CHEN Liping 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2007年第5期16-22,共7页
Aiming at the approximate error of commonly used methods on calculation of hydrostatic pressures of closed hydrostatic guideways with multiple pockets, a more accurate solution is proposed. Taking design of beam & sl... Aiming at the approximate error of commonly used methods on calculation of hydrostatic pressures of closed hydrostatic guideways with multiple pockets, a more accurate solution is proposed. Taking design of beam & slide-rest guideways for a heavy duty CNC vertical turning mill as an example, under an assumption that stiffnesses of guideways and their jointing structure are sufficiently large, the pressures of the pockets can be attained by adding a co-planarity equation that constrains pocket centers. Then, an optimization model is built to minimize the highest pocket pressure under additional constraints that are posed on the highest seal margin pressure, the highest levitating pressure of the pockets, and the maximum deformation of the guideways. The optimization problem is solved sequentially by using the methods of design of experiments and adaptive simulated annealing on iSIGHT software platform. The results show significant improvements to the original design. Optimized maximum hydrostatic pressure meets the requirement of hydraulic system. 展开更多
关键词 CNC vertical turning mill beam Slide rest Hydrostatic guideway Parameter optimization
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Beam Steering Analysis in Optically Phased Vertical Cavity Surface Emitting Laser Array
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作者 荀孟 孙昀 +5 位作者 徐晨 解意洋 金智 周静涛 刘新宇 吴德馨 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第3期30-34,共5页
Beam steering in implant defined coherently coupled vertical cavity surface emitting laser (VCSEL) arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences amo... Beam steering in implant defined coherently coupled vertical cavity surface emitting laser (VCSEL) arrays is simulated using the FDTD solution software. Angular deflection dependent on relative phase differences among elements, inter-element spacing, element size and emitted wavelength is analyzed detailedly and systematically. We design and fabricate 1×2 implant defined VCSEL arrays for optimum beam steering performance. Electroni- cally controlled beam steering with a maximum deflection angle of 1.6° is successfully achieved in the 1 × 2 VCSEL arrays. The percentage of the power in the central lobe is above 39% when steering. The results show that the steering is controllable. Compared with other beam steering methods, the fabrication process is simple and of low cost. 展开更多
关键词 VCSEL beam Steering Analysis in Optically Phased vertical Cavity Surface Emitting Laser Array
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A Limited Feedback Transmission Scheme Based on MS Compensation in the 3D MIMO System
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作者 HAN Dongsheng YANG Wei +1 位作者 PENG Yuefeng ZHU Yuan 《China Communications》 SCIE CSCD 2014年第A02期102-110,共9页
In a three-dimensional (3D) multiple- input multiple-output (MIMO) system, the base station can use both horizontal and vertical spaces, transmitting spatial beam to users more accurately. This system has caught t... In a three-dimensional (3D) multiple- input multiple-output (MIMO) system, the base station can use both horizontal and vertical spaces, transmitting spatial beam to users more accurately. This system has caught the attention of researchers in recent years. The existing research on the 3D MIMO technology is based on the assumption that the base station can acquire the ideal channel state information (CSI), which is not actually the case in real systems. Therefore, this paper introduces a limited feedback transmission scheme based on mobile station (MS) compensation in the 3D MIMO system. In this scheme, the vertical antenna gain of the 3D MIMO system compensation is assigned to the MS. Two CSI-RS ports are configured at the base station, omnidirectional CSI-RS port and partial CSI-RS port. The MS can calculate the horizontal CSI and the vertical beam gain according to omnidirectional CSI-RS port and partial CSI- RS port, respectively. Partial CSI-RS resources are used to calculate the channel after being weighted by the vertical beam vector, MS selects the optimal vertical precoding vector. Simulations show that compared with the reference strategy, the transmission scheme with limited feedback based on the MS compensation proposed in this article has more advantages. The average spectral efficiency of the system and the cell edge spectral efficiency can be greatly improved. 展开更多
关键词 3D MIMO CSI FEEDBACK vertical beam gain PRECODING
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