Xiao H.,University of Science and Technology Beijing |
Zhou X.,China Ship Research and Development Academy |
Liu J.,Chongqing University |
Shao Y.,Chongqing University
Measurement: Journal of the International Measurement Confederation | Year: 2017
In this work, an eight-degree-of-freedom (DOF) dynamic model of the gear-shaft-bearing-housing system is established and the vertical vibration transmission and energy dissipation characteristics through the multiple transmitting interfaces under the impulse force due to gear fault are studied. The elastic deformations at the interfaces between gear and shaft, inner race and outer race, outer race and housing are formulated by the corresponding contact stiffness. The housing compliance is also included. A half-sine impulse force with two characteristic parameters as amplitude and time duration, which are associated with the defect type and size, is employed to represent the effect of gear fault on the system dynamics. The acceleration responses for different transmitting components as gear, inner race, outer race and housing are calculated for different impulse time duration, different impulse force amplitudes and shaft rotating speeds. The vibration transmission and energy dissipation through the multiple interfaces are characterized by the defined vibration transmission ratio and energy dissipation ratio. Obvious attenuation in acceleration magnitude is observed between the transmitting components from gear to housing. The maximum attenuation occurs at the transmission from inner race to outer race, while the minimum is between the outer race and the housing. The time duration of the impulse force determines the resonance and also the vibration transmission characteristics of the system. The energy dissipation increases nonlinearly with the amplitude of the applied impulse force. Results also suggest that the interface between inner race and outer race, and the interface between gear and shaft dissipated about 60% and 40% of the total energy, are the main sources of energy dissipation in the system. However, the shaft rotating speed has limited effect on the vertical impulse vibration amplitude, vibration transmission and energy dissipation. Experimental validation is performed, which supports the characteristics obtained from numerical results. © 2017 Elsevier Ltd
Li W.,Beihang University |
Li N.,Beihang University |
Li N.,China Ship Research and Development Academy
Science China Information Sciences | Year: 2012
This work aims to build a semantic framework for automated debugging. A debugging process consists of tracing, locating, and fixing processes consecutively. The first two processes are accomplished by a tracing procedure and a locating procedure, respectively. The tracing procedure reproduces the execution of the failed test case with well-designed data structures and saves necessary information for locating bugs. The locating procedure will use the information obtained from the tracing procedure to locate ill-designed statements and to generate a system of fix-equations, whose solution will be used to fix the bugs. A structural operational semantics is given to define the functions of the tracing and locating procedures. Both of them are proved to terminate. The main task of fixing process is to solve the fix-equations. It turns out that for a given failed test case, there exist four types of fix-equations and three different solutions: 1) The bug is solvable, i. e., there exists a solution of the system of fix-equations, and the program can be repaired. 2) There exists a structural design error in the program, i. e., the system of fix-equations generated at each round of the locating procedure is solvable, but a new bug will arise when the old bug is being fixed. 3) There exists a logical design error, and the system of fix-equations is not solvable. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.
Song N.,Beihang University |
Cai Q.,Beihang University |
Yang G.,Beihang University |
Yin H.,China Ship Research and Development Academy
Measurement Science and Technology | Year: 2013
The rotational inertial navigation system (INS) has received wide attention in recent years because it can achieve high precision without using costly inertial sensors. However, the introduction of the turntable causes additional errors, including mounting errors between the inertial measurement unit (IMU) axes and the turntable axes. Analysis, calibration and compensation of the mounting errors are necessary in rotational INS. In this paper, the mounting errors are introduced into the sensor model of a dual-axis rotational INS. Analysing the improved model indicated that the mounting errors' effect on the IMU errors is inconspicuous, but the effect on the output attitude is significant. If the output attitude is not required, the mounting errors can be ignored; conversely, it is important to calibrate and compensate for such errors. A calibration method for the mounting errors is designed using the thin-shell (TS) algorithm, and the method's precision has the same order of magnitude as the residuals of gyro misalignment in the simulation test. Laboratory experimental results validate the theory and proved that the calibration and compensation method for mounting errors proposed in this paper helps improve the output attitude's precision without a precise installation. © 2013 IOP Publishing Ltd.
Tian Z.-D.,Beijing West Third Ring Road19 A 4 |
Ji F.,Harbin Engineering University |
Ji F.,China Ship Research and Development Academy
Chuan Bo Li Xue/Journal of Ship Mechanics | Year: 2011
Based on wave theory, the characteristics of wave propagation of typical hull structure from blocking mass are discussed. Concerned with assemble process, the influence of eccentricity of blocking mass to its vibration isolation performance is analyzed. From the engineering application point of view, the blocking mass ribbon is introduced into rigid vibration design of typical base structure. Combining the acoustic-structural coupled method and Statistical Energy Analysis, the full-band influences of blocking mass ribbon cross-section size, cross-section shape parameters and layout location to base isolation performance are discussed. On this base, the quick-engineering prediction method of base blocking mass ribbon in power cabin is developed, which aims to provide reference for primary acoustic design of typical hull structure.
Zheng M.,China Ship Research and Development Academy
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2015
To determine the angle and position in width direction of angled deck objectively, this paper reviewed and analyzed the factors that influence the angled deck general arrangements. Based on several schemes of foreign mature aircraft carriers, support vector machine (SVM) model was introduced to regression and gain the trand and characteristics of angled deck arrangement. The regression for former Soviet Union Ulyanovsk aircraft carrier demonstrates that the accuracy and validity of this method is good. © 2015, Wuhan University of Technology. All right reserved.
Liu S.,Harbin Engineering University |
Cheng Y.,China Ship Research and Development Academy
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015
In order to solve the problem that the generation system with constant power loads can result in voltage instability in shipboard medium voltage DC integrated power systems, small signal model based eigenvalue stability analysis was employed in this paper. A constant RL-branch synchronous generator voltage-behind-reactance (VBR) model combining diode rectifier average value model modeling approach was proposed. Low pass filters are employed to solve the problem that the system can not be conducted in ordinary differential equation (ODE) form directly, and the nonlinear ODE model for the generation system was constructed. The model was validated by detailed numerical simulation. Based on the ODE model, the small signal model was constructed and the stability of the generation system was analyzed by the eigenvalue loci of equilibrium points. The stability of the system with different inputs and design parameters was investigated, and the stability regions were obtained. The results of the stability analysis were validated by both the quantitative simulation and qualitative analysis. © 2015 Chin. Soc. for Elec. Eng.
Ji F.,China Ship Research and Development Academy |
Ji F.,Harbin Engineering University
Gongcheng Lixue/Engineering Mechanics | Year: 2013
Through the combination of hollow blocking mass with polyurethane sandwich plate, the composite low-noise brace structure is designed. Its preliminary marine application is also presented. On this basis, the large scale double shells' underwater model test of vibration, sound radiation and input power flow is carried out. The test data show that the outer shell 20Hz-3000Hz vibration acceleration level is reduced by 3.1dB, the near field sound radiation pressure at 5m is reduced by 7.2dB. The 90°-270° clockwise circumferential distribution of sound pressure has the highest noise reduction. The input power flow is also obviously attenuated, which is single-peaked and moves to lower frequency.
He C.,Northwestern Polytechnical University |
Huang J.,Northwestern Polytechnical University |
Yan Z.,China Ship Research and Development Academy |
Zhang Q.,Northwestern Polytechnical University
Science China Information Sciences | Year: 2011
A novel M-ary code division multiple access (M-ary CDMA) underwater acoustic communication (UAC) that utilizes quasi-orthogonal sequences has been proposed for the multiple mobile unmanned underwater vehicle (UUV). Its performance has been verified in both four-user synchronous and three-user asynchronous scenarios through a lake experiment over a very shallow-water channel. At a chip rate of 2 kilochips per second, good bandwidth efficiency and robust links have been achieved both at 5 and 15 km distances. The performance of M-ary CDMA in mobile condition (3 m/s) is demonstrated by using the recorded lake experimental data. Experimental results show that the proposed scheme is suitable for multi-user communication platform in long-range shallow-water channel with simple receiver algorithms. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.
Pan D.-Y.,Zhejiang University |
Liu H.,China Ship Research and Development Academy |
Shao X.-M.,Zhejiang University
Journal of Hydrodynamics | Year: 2010
This paper studies the oscillation behavior of a flexible plate in the wake of a D-section cylinder. The interaction between the flexible body and its surrounding vortices is investigated. A modified immersed boundary method is used to solve the motion of fluid, integrated with a linearized Euler-Bernoulli beam model to govern the motion of the flexible plate. Results show that, when the distance between cylinder and plate is small, the surface of the plate is surrounded by vortices layers and the plate oscillates periodically, with amplitude similar to the cylinder movement. However, if the distance becomes large, we find that the vortices are shed from the D-cylinder in front of the plate, and the incoming vortices make the plate oscillate with large amplitude at the beginning and then slant laterally. Also, the amplitude becomes smaller compared to the case of the small distance. © 2010 Publishing House for Journal of Hydrodynamics.
Zhu Y.,China Ship Research and Development Academy
7th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2011 | Year: 2011
Dynamic Spectrum Anti-Jamming (DSAJ) is a new system of anti-jamming communications. By employing the opportunistic spectrum access concept of cognitive radio, DSAJ treats subbands in its entire system bandwidth as "spectrum holes", where there is no jamming or the power of jamming is below a particular threshold. Transmit frequencies are determined via real-time spectrum hole detection. System parameters are adjusted during the communication process according to the variations of jamming in the spectrum holes. These measures minimize the detriment of jamming and provide robust anti-jamming capability for the DSAJ system. Processing gain of DSAJ is analyzed and compared with the conventional frequency hopping (FH) over various types of jamming. Results show that significant improvement can be obtained by DSAJ. © 2010 IEEE.