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Liu Y.-P.,Jiangsu Electrical Power Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The support system composed of double arched beams and bored piles in foundation pits has many advantages, such as better whole stability, smaller displacement of pile top, larger excavation space, shorter construction period and lower cost, compared with other systems of large and deep foundation pits. A foundation pit of the building with a three-storeyed basement is taken as a study case. The problem of less construction space and complex surrounding environment is effectively solved. More economic benefits are obtained and the cost is further reduced by the application of local reinforcement and two piles united into one pile.

Jian B.,Chongqing University | Wang G.-B.,Jiangsu Electrical Power Design Institute | Xie X.,Chongqing University
Gongcheng Lixue/Engineering Mechanics | Year: 2014

Based on the analysis of the seismic performance of 16 partially prestressed concrete (PPC) frame structures designed according to China current codes, the quantitative index of PPC frame performance levels and the reliability of a design displacement in Direct Displacement-Based Design (DDBD) had been analyzed. After three performance levels of basic integrity, life safety and collapse prevention defined, crack width, bearing capacity had been suggested as a quantitative reference index and the corresponding interstory drift ratio as a final quantitative index. At the same time, taking the interstory drift ratio corresponding to a quantitative index as resistances and corresponding to expected earthquakes as effects, a simplified method had been put forward, in which reliability can be taken into account in DDBD and associated to the reliability level of current codes. In this method, the error arose from the coefficient of variation can be avoid greatly and different requirements can be satisfied under an identical performance level.

Jia Y.,Xian Jiaotong University | Zhao J.,Xian Jiaotong University | Zhao J.,Jiangsu Electrical Power Design Institute | Fu X.,Xian Jiaotong University
IEEE Transactions on Power Electronics | Year: 2014

A direct grid current control strategy for LCL-filtered grid-connected inverters is proposed in this paper. The conventional current control strategies are analyzed and compared, and then the necessity of direct grid current control is presented to mitigate the grid voltage disturbance. In the proposed control strategy, the virtual resistance based on the capacitance current is used to realize active damping, zero compensation is brought in to enhance the stability, and the proportional resonant (PR) controller under two-phase static coordinate is designed to track the ac reference current as well as to avoid the strong coupling brought by the coordinate transformation. Under the distortion grid voltage, the PR plus harmonic compensator (PR+HC) structure is adopted to restrain the distortion of the grid current. Finally, the proposed control strategy is verified by the experimental results. © 1986-2012 IEEE.

Huang J.,Jiangsu Electrical Power Design Institute | Wang X.,Nanjing University of Aeronautics and Astronautics
Advanced Composites Letters | Year: 2011

Composite tubes with different cross-sectional shapes, including quarter circle, half circle and three-quarter circle, are axially crushed to study the boundary effects on the energy absorption of cylindrical shells and develop a semi-empirical analysis method for the crashworthy design of composite structures. It is observed experimentally that all specimens crush from the chamfered end and exhibit stable progressive crushing with similar macroscopic failure modes. Experimental results indicate that the load-displacement curves of all specimens are similar to those of full-circle tubes. And the quarter-circle tubes show the lowest energy absorption capability, while the half-circle tubes and three-quarter-circle tubes show almost the same energy absorption capability. It is found that quarter-circle thermoset tubes without and with one free edge provide 19% and 13% higher energy absorption capability than the quarter-circle thermoset tubes with two free edges; while quarter-circle thermoplastic tubes without and with one free edge provide 6% and 2% higher energy absorption capability than the quarter-circle thermoplastic tubes with two free edges, respectively. It is also found that the semi-empirical analysis method based on crush data and boundary effects of the quarter-circle tubes can accurately predict the energy absorption capability of half-circle or full-circle tubes.

Pan X.,Jiangsu Electrical Power Design Institute
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

It is necessary to describe the statistical properties of wind speed using three-parameter Weibull distribution for offshore wind energy resource assessment and utilization. According to the functional relation between parameters and probability-weighted moments (PWM), the functions were fitted with the shape parameter and PWM using logistic curve. Two formulae of parameter estimation were studied out based on low-order insufficient and exceeding PWM. Accuracy test results show that these formulae had higher precision in large-scale range. Through comparative analysis with high-order PWM method for example, the author believes the low-order PWM methods in this paper are worth popularizing. ©2012 Chinese Society for Electrical Engineering.

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