Xian University of Posts & Telecommunications
Xian University of Posts & Telecommunications
Jing J.,Xian University of Posts & Telecommunications |
ZhongFu X.,Xian University of Posts & Telecommunications
International Journal of Future Generation Communication and Networking | Year: 2016
Large-scale Multiple-Input Multiple-Output (MIMO) can promise high spectrum efficiency and low multi-user interference. But the pilot contamination of the uplink channel estimation is the obstacle to acquire the great performance gains. A novel iterative joint channel estimation and detection algorithm is proposed. First, the initial channel information is estimated with the uplink pilots. Then the receiver detects the receiving signals with Match Filter (MF) precoding and Minimum Mean Square Error (MMSE) criterion based on the initial channel estimation. The receiving signal acquires the great large-scale MIMO detection gains and is more lightly interfered than the multiplexed uplink pilots because of the non-coherence of the transmitted data. Thus, it is in turn applied to suppress the pilot contamination in the channel estimation. In the iteration, the updated channel estimation is used for the data detection in the next loop. The theoretical analysis shows that the interference items in the detected signals and the channel estimation are continually decreased with the number of the iteration increasing. At last, the numerical results prove that, the proposed algorithm has significant performance gains comparing with the conventional algorithms. After only one iteration in light pilot contamination cases and three iteration in severe pilot contamination cases, it can obtain the detected data and the channel estimation information with the required performance. The proposed algorithm effectively improves the detection performance and suppress the pilot contamination of the uplink channel estimation, and can be worthy for the large-scale MIMO system. © 2016 SERSC.
Qiao L.,Xian University of Posts and Telecommunications |
Zhao D.,Xian University of Posts & Telecommunications |
Li C.,Xian University of Posts and Telecommunications
Journal of Applied Optics | Year: 2016
In order to obtain the infrared/visible/low-level light images of targets, a multi-channel photoelectric system optical axis parallelism calibration device was proposed. This device could easily load multi-channel photoelectric detection system, it realized the adjustment for the optical axis parallism in the azimuth and pitch directions mainly through the waist-shaped hole of the backplane clearance and the pad under repair backplane, to meet the optical axis parallelism not more than 15″. The instrument is characterized by simply adjusting the optical system of optical axis parallelism for the first time, it is possible to achieve different detectors repeating interchangeable lenses, and the repeatable positioning accuracy is higher than 0.01 mm. In addtional, the instrument can be easily loaded on other light equipments, such as photoelectric rotary table, convenient for field experiments, which can satify the requirement for using. © 2016, Editorial Board, Journal of Applied Optics. All right reserved.
Dong Q.,Xian University of Posts & Telecommunications |
Hui Z.,Xian University of Posts & Telecommunications |
Ruan C.,CAS Xi'an Institute of Optics and Precision Mechanic
Journal of Applied Optics | Year: 2016
An optical fiber displacement-vibration sensor using the incoherent light as a light source and the mirror as a reflective surface was analyzed. The analytic expressions of the optical fiber output power and the measurement distance were derived. The relationship between power ratio and measurement distance was detailedly investigated based on different optical fiber radii, different numerical apertures, different spacings and included angles between transmitting and receiving optical fibers. The results of numerical simulation show that the measurement precision and scope are affected by the optical fiber radius, the optical fiber numerical aperture, the distance and axis angle of both transmitting and receiving optical fibers. By analyzing the variation curves of distance and output power ratio, it is helpful to select the appropriate sensor according to the measurement target in practical engineering applications. Moreover, the measurement error was discussed. The results shows that the measuring range of distance is increased with the increasing of optic fiber included angle, while the error rate is reduced. The error rate is 1% for the included angle of 0.25°. © 2016, Editorial Board, Journal of Applied Optics. All right reserved.
Guo B.,Xian University Of Posts & Telecommunications
International Journal of Simulation: Systems, Science and Technology | Year: 2016
With the rapid economic development and progress of society, there is a need for increasing the number of sports venues. Through the construction and operation management of stadiums, and full analysis of the current situation, it is clear that faced with engineering design and construction problems operators often find it difficult to meet completion targets. Therefore, in order to achieve social and economic benefits of the overall optimization and multi-party major sports venues, the technology must include: i) the full life-cycle management theory and methods, ii) in-depth study of the construction of stadium implementation, iii) operational management for sustainable development, and iv) important stadiums theoretical and practical significant issues. This paper attempts to improve the overall effectiveness and efficiency in the use of large stadia by means of architectural design using concepts of further expansions. We propose BIM-based information management system to include architecture, structure and extension mechanisms. © 2016, UK Simulation Society. All rights reserved.
Zhao D.-S.,Xian University of Posts & Telecommunications |
Wu R.-J.,Xian University of Posts & Telecommunications
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016
The pose matrix of a 6-SPS mechanism was described with the quaternion method. The matrix and vector coordinates were expanded into a 4-dimensional form to derive the motion equations of the mechanism without clearance. Then, the novel kinematic Jacobi matrixes JA and JB of the mechanism motion were achieved. On this basis, the movement coefficient matrixes of two S-pairs co-linkage and a different-linkage mechanism were derived with the continuous contact model. Determinants of movement coefficients were expanded, respectively. Subsequently, the trajectory equations containing the first category of singularity and the second category of singularity of mechanisms containing clearance were derived, respectively. Using MATLAB software, the three-dimensional track surfaces of the first category and the second category of pose-attitude singular trajectories at a given location of the mechanism were obtained. The comparison between two types of singularity trajectory surfaces of mechanisms containing clearance showed that the influence of mechanism clearance on the second category of singular it is greater than that on the first category; among the two types of singularity tracks, the influence of mechanism clearance in different-linkage S pairs is greater than that in co-linkage S pairs; the singular point on the trajectory surface of a mechanism without clearance is taken as a reference point, comparing the singular points on the singularity trajectory surface of a mechanism containing clearance corresponding to the reference point, a singular area with respect to the reference point can be found. © 2016, Editorial Office of Journal of Vibration and Shock. All right reserved.
Tong X.,Xian University Of Posts & Telecommunications |
Sun T.,Xian University Of Posts & Telecommunications
International Journal of Electronics | Year: 2016
A multi-output and high-precision output-tuning technique in a low-dropout regulator (LDO) for multi-reference low-power SAR ADC is proposed in this article. A programmable resistor string is utilised for multi-output, and a tuneable resistor ladder is introduced in the feedback network for high-precision LDO output control. The applicability and superiority of this proposed approach are verified by the design of a 65 nm CMOS LDO with programmable output. The design results show that the LDO output ranges from 0.4 to 1.2 V with 0.2 V/step, and the output voltage can be precisely tuned by 0.05 V/step within a range of 0.8–1.15 V. The line regulation of this LDO is about 0.27 mV/V. The multi-output ability enables the LDO to drive five light loads simultaneously, and the high-precision tuning ability can effectively overcome the output errors caused by power supply variation, temperature drift and other non-ideal factors. © 2016 Informa UK Limited, trading as Taylor & Francis Group
Tong X.,Xian University of Posts & Telecommunications |
Zhang Y.,Xian University of Posts & Telecommunications
Xitong Fangzhen Xuebao / Journal of System Simulation | Year: 2016
D/A conversion network of SAR (SAR: Successive Approximation Register) ADC was discussed. The energy model of the capacitor array in R-C hybrid D/A network was established by using MATLAB. With the combination of resistor string's static power and capacitor array's switching power, the power model of the R-C hybrid network in SAR ADC was proposed based on a 65nm CMOS process. Furthermore, by considering matching requirement for the passive components, 12-bit R-C hybrid D/A networks with "5+7", "6+6" and "7+5" type of structures were simulated and compared. The research can provide significant guidance for circuit design and optimization of low-power SAR ADC. © 2016, The Editorial Board of Journal of System Simulation. All right reserved.
Zhang X.,Xian University of Posts & Telecommunications
Guti Dianzixue Yanjiu Yu Jinzhan/Research and Progress of Solid State Electronics | Year: 2015
Temperature is one of the key factors that affect the performance index and limit the application of micro-mechanical accelerometer. In this paper, the research of MEMS accelerometers was introduced and the influence mechanism of the temperature on MEMS accelerometers was analyzed briefly. Several main research methods reported by research institutions in recent years on how to reduce the temperature drift of MEMS accelerometer were elaborated in detail. These works could provide a reference for advancing the research field. © 2015, Editorial Office of «Res. Prog. SSE». All right reserved.
Xiao Y.-L.,Xian University of Posts & Telecommunications |
Wang Y.-M.,Xidian University |
Pang L.-J.,Xidian University |
Tan S.-C.,Xidian University
Tongxin Xuebao/Journal on Communications | Year: 2014
To solve the existing problems caused by that the third version of WLAN authentication infrastructure (WAI) protocol was used to establish WLAN Mesh security association, a WLAN Mesh security association scheme based on an improved WAI protocol was proposed. The results of performance analysis of the scheme show that the scheme improves the performance of WLAN Mesh security association, especially decreases the overhead of the authentication server (AS). Then, on basis of this scheme, a WLAN Mesh security association scheme in trusted computing environment was put forward to meet the demand of trusted computing environment. Moreover, the two WLAN Mesh security association schemes were proved secure in the strand space model (SSM).
Zhang Z.,Xian University of Posts & Telecommunications
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2015
Based on the work status of the aero-engine turbine blade, the contact fatigue tests of modeling specimens of tenon/groove were carried out. A fatigue crack growth life model of the modeling specimens was established. The crystallographic finite element program was implemented to study the stress field of the tenon/groove. Crack growth lives obtained from the finite element analysis had a good agreement with the results of experiment. It was demonstrated that the life model could be used in engineering to predict the remaining life of turbine disk. ©, 2015, Journal of Mechanical Strength. All right reserved.