Chongqing Communication Institute

Chongqing, China

Chongqing Communication Institute

Chongqing, China

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Liu H.,Chongqing Communication Institute | Tao X.,Harbin Institute of Technology
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2013

A finite fault based hybrid source model of the great Wenchuan earthquake with magnitude 8.0 is built in this paper. The global parameters are mainly determined from the regional seismo-tectonics, structure of the crust, seismicity and a set of semi-experiential calibration laws. The local parameters consist of two groups. One is on asperity, the other one is on k square distribution. Both of them are generated from the truncated Normal distribution with mean and standard deviation values estimated by a set of calibration laws. 30 source models are presented finally.


Zhang Y.,North China University of Technology | Xie W.,North China University of Technology | Zhang Y.,Chongqing Communication Institute
IET Power Electronics | Year: 2014

Direct power control (DPC) is a powerful control scheme for three-phase AC/DC converters, because of its decoupled control of active/reactive power and quick dynamic response with simple structure. However, relative high-power ripples at steady state and variable switching frequency can be observed in conventional DPC. Furthermore, the harmonic spectrum of current is broad and not easy to be filtered. This study tries to improve the steady-state performance of conventional DPC by using deadbeat power control. Two kinds of deadbeat control methods are proposed and the first one aims to achieve deadbeat control of active power, whereas the second one aims to achieve deadbeat control of both active power and reactive power. Compared with conventional DPC, the two deadbeat power control methods achieve significant steady-state performance improvement in terms of lower power ripples and less current harmonics, even if the sampling frequency is much lower. Moreover, the quick dynamic response of conventional DPC is maintained in the proposed methods. The two kinds of deadbeat methods are comparatively studied, with the basic DPC as the benchmark. The presented experimental results validate the effectiveness of the proposed deadbeat power control methods. © The Institution of Engineering and Technology 2014.


Zhang Y.,North China University of Technology | Xie W.,North China University of Technology | Li Z.,North China University of Technology | Zhang Y.,Chongqing Communication Institute
IEEE Transactions on Power Electronics | Year: 2013

This paper proposes an improved model predictive direct power control (MPDPC) for a pulse width modulation (PWM) rectifier by using a duty cycle control. The conventional MPDPC achieves good steady-state performance and quick dynamic response by selecting the best voltage vector, which minimizes the errors between the reference power and the real power. However, due to the limited number of voltage vectors in a two-level converter, the sampling frequency has to be high to achieve satisfactory performance. This paper introduces the concept of a duty cycle control in the MPDPC by allocating a fraction of control period for a nonzero voltage vector and the rest time for a zero vector. The nonzero vector is selected by evaluating the effects of each nonzero vector and its duration is obtained based on the principle of power errors minimization. Simulation and experimental results prove that, compared to the conventional MPDPC, the proposed MPDPC with duty cycle achieves further steady-state performance improvement without affecting the dynamic response at a small cost of control complexity increase. © 1986-2012 IEEE.


Zhang Y.,North China University of Technology | Li Z.,North China University of Technology | Zhang Y.,Chongqing Communication Institute | Xie W.,North China University of Technology | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Conventional switching-table-based direct power control (STDPC) presents irregular power ripples and variable switching frequency, due to the use of predefined switching table and hysteresis comparators. This paper proposes an improved DPC for three-phase pulsewidth modulation (PWM) rectifier with simple calculation. The concept of duty cycle control is introduced in DPC to allocate only a fraction of control period to the voltage vector selected from conventional switching table in DPC, while a null vector is applied for the rest of time. The main advantages of the proposed duty cycle control are twofold. On one hand, it is independent of rectifier parameter such as line-side inductance, hence strong robustness against inductance variations is obtained. On the other hand, the principle to obtain the duty cycle is very simple and easy to implement. Compared to conventional DPC, significant power ripple reduction and more sinusoidal grid current can be observed in the improved DPC. The presented simulation results and laboratory tests validate the effectiveness of the proposed method. © 1986-2012 IEEE.


Zhang G.,Chongqing University | Tang B.,Chongqing University | Tang G.,Chongqing Communication Institute
Measurement: Journal of the International Measurement Confederation | Year: 2012

An improved stochastic subspace identification algorithm is introduced to solve the low computational efficiency problem of the Data-driven stochastic subspace identification. Compared with the conventional algorithm, it needs much less cost of memory and computing time because it does not have a process of the QR decomposition of Hankel matrix. Model similarity index is proposed to measure the reliability of the modes obtained by the improved stochastic subspace identification. Furthermore, the stabilization diagram in combination with the modal similarity index is adopted to effectively indicate spurious modes resulting from noise and model redundancy. A criterion named the modal norm is introduced to indicate the dominating mode. A numerical example on the parameter estimation of a linear time-invariant system of 7 degrees of freedom and one experimental example on the parameter estimation of Chaotianmen bridge model in Chongqing are presented to demonstrate the efficacy of the method. © 2012 Elsevier Ltd. All rights reserved.


Zhang Y.,North China University of Technology | Xie W.,North China University of Technology | Li Z.,North China University of Technology | Zhang Y.,Chongqing Communication Institute
IEEE Transactions on Industrial Electronics | Year: 2014

Conventional model predictive power control (MPPC) achieves good steady-state performance and quick dynamic response by minimizing a cost function relating to the power errors. However, applying single voltage vector during the whole control period fails to reduce the power ripples to a minimal value; particularly in the two-level converter with limited switching states. Recently, the concept of duty cycle control has been introduced in MPPC to achieve further power ripple reduction. Although better steady-state performance is obtained, a lot of calculations are needed when deciding the best voltage vector and its corresponding duration. This paper proposes a low-complexity MPPC with quick voltage selection and fast duty cycle calculation. Different from prior MPPC, the negative conjugate of complex power in synchronous frame is selected as the control variable. As a result, only one prediction is required to select the best voltage vector, and its duration is determined base on the principle of error minimization of both active and reactive power. Further study reveals that the proposed low-complexity MPPC is equivalent to the recently reported MPPC with duty cycle control. Simulation and experimental results obtained from a two-level three-phase ac/dc converter are presented to confirm the theoretical study and the effectiveness of the proposed method. © 1982-2012 IEEE.


Zeng F.,Chongqing Communication Institute
IEEE Communications Letters | Year: 2014

This letter discusses the construction of 16-quadratic-amplitude modulation (QAM) Golay complementary sequences of length N=2m. Based on the standard binary Golay-Davis-Jedwab (GDJ) complementary sequences (CSs), we present a method to convert the aforementioned GDJ CSs into the required sequences. The resultant sequences have the upper bounds 3.6N, 2.8N, 2N, 1.2N, and 0.4N of peak envelope powers, respectively, depending on the choices of their offsets. The numbers of the proposed sequences, corresponding to five upper bounds referred to above, are (24m-16)(m/2)2m+1, 128(m-1)(m/2)2m+1, (176m-160)(m/2)2m+1, 128(m-1)(m/2)2m+1, and (24m-16)(m/2)2m+1. Our sequences can be potentially applied to the QAM systems whose input signals are binary signals. © 1997-2012 IEEE.


Zeng F.,Chongqing Communication Institute
International Conference on Communication Technology Proceedings, ICCT | Year: 2015

This paper discusses the relationship between Zeng, et al.'s and Xu, et al.'s constructions yielding perfect sequences over 8-QAM constellation. By shucking off extrinsic difference of two types of constructions, their essence is found. We verify that two types of constructions are equivalent under unit constant transform. Hence, we draw the conclusion that Xu, et al.'s constructions are the special case of Zeng, et al.'s constructions. © 2015 IEEE.


Li Q.,Chongqing Communication Institute
Modern Tunnelling Technology | Year: 2014

The Nanhu tunnel goes beneath the Nanhu lake park in Nanning City, of which around 400 m section lies under the Nanhu lake. Construction of Nanhu tunnel is at high risk due to the poor geological conditions and high pressure of groundwater. To ensure safety during construction of foundation pit, based on the experiences of similar projects in past, it put forward a combined vertical water sealing by curtain grouting consisting of deep mixing piles (at upper slightly permeable layer) and high pressure jet grouting piles (at lower highly permeable layer) and dewatering by casing wells in foundation pit for the special geological condition in Nanning area to effectively control groundwater under high pressure during the period of construction. The soil nailing is applied as support of pit slope at the lake section and SMW method piles combining with inner support system are adopted as a support of foundation pit along lakeshore to ensure the construction safety. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.


Zeng F.,Chongqing Communication Institute | Zhang Z.,Chongqing Communication Institute
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences | Year: 2011

Based on the known quadriphase zero correlation zone (ZCZ) sequences ZCZ4(N, M, T), four families of 16-QAM sequences with ZCZ are presented, where the term "QAM sequences" means the sequences over the quadrature amplitude modulation (QAM) constellation. When the quadriphase ZCZ sequences employed by this letter arrive at the theoretical bound on the ZCZ sequences, and are of the even family size M or the odd width T of ZCZ, two of the resulting four 16-QAM sequence sets satisfy the bound referred to above. The proposed sequences can be potentially applied to communication systems using 16-QAM constellation as spreading sequences so that the multiple access interference (MAI) and multi-path interference (MPI) are removed synchronously. © 2011 The Institute of Electronics, Information and Communication Engineers.

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