China Ship Development And Design Center
China Ship Development And Design Center
Liu L.,China Ship Development And Design Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017
In this paper, a method for individual tree shape modeling and canopy coverage delineation is provided for high density airborne LiDAR data. Three basic 3-D canopy shape models are introduced as fundamental assumptions, and then an iterative algorithm for calculating tree canopy window is implemented. After that, the prototype test is carried out with simulated forest point data which visually shows a valid result. After that, a real mixed forest LiDAR dataset is being put into experiment. Based on the same theory, the output and a statistical analysis reveals that the proposed method can yield an effective and distinguishable extraction of different tree canopy coverage delineation. © 2017 COPYRIGHT SPIE.
Liu Y.,China Ship Development And Design Center
MATEC Web of Conferences | Year: 2017
Large uniform load on plane widely exists in the structural design of ship equipment. In order to verify the reasonability of equipment structural design, a test system of structural strength is needed to make structural test. To this end, a strength test system is developed. In this test system, a concentrated load, which is equal to actual uniform surface load that acts on the equipment, is imposed on the loading part by Hydraulic Loading Method. Then, the concentrated load is turned into several concentrated loads uniformly distributed in loaded area of the equipment structure. Stress measurement system is applied to make a tracking measurement of the series of points in the equipment structure. The test data is professionally recorded with a real-Time analysis. In order to verify the feasibility of the test system, a complete test platform for a ship equipment structure is designed, furtherly a contrastive analysis has been undertaken between the outcome of the test system and the one of finite element simulation, and it turns out that the application of the test system is feasible. © The Authors, published by EDP Sciences, 2017.
Zhou H.,China Ship Development And Design Center
Ship Building of China | Year: 2017
Fatigue fracture forms are investigated for welding butt joints, which are subject to longitudinal bending cyclic load and vertical compressing cyclic load. Based on the shear strain and the normal strain on the maximal shear strain plane, a method is proposed to estimate the crack propagation life. Compared with other methods, this method is more practicable and has physical significance. © 2017, Editorial Office of Ship Building of China. All right reserved.
Huang Z.,China Ship Development And Design Center
Journal of Physics: Conference Series | Year: 2016
Rub-impact and fatigue crack are two important rotor faults. Based on the crack theory, an improved switching crack model is presented. Dynamic characteristics of a rotor-bearing system with imbalance, rub-impact and transverse crack are attempted. Various nonlinear dynamic phenomena are analyzed using numerical method. The results reveal that unstable form of the rotor system with coupling faults is extremely complex as the rotating speed increases and there are some low frequencies with large amplitude. The influence of crack depth and angle on the dynamic behavior of a cracked rotor is important insomuch as the quasi-periodical and chaotic motions in system response will occur along with different parameters. It is indicated that this study can contribute to a further understanding of the nonlinear dynamics of such a rotor system with coupling faults of crack and rub-impact. © Published under licence by IOP Publishing Ltd.
Juanjuan Z.,China Ship Development And Design Center
2016 2nd IEEE International Conference on Computer and Communications, ICCC 2016 - Proceedings | Year: 2017
A flying state transfer model of an anti-radiation missile (ARM) and an evaluation model of the ARM landing points were established by using probability tree, based on the theory of excursion link to antagonize ARM. Then, a flow chart for the simulations of excursion link to antagonize ARM was obtained. The influences of characteristics, i.e. resolving angle, velocity and maximum normal overload of ARM, and the parameters of decoying system, i.e. the working time of radiation sources and distance between radiation sources, on protected probabilities of radar and additive radiation sources were analyzed, regarding excursion link and excursion equilateral triangle. Finally, landing point pictures of ARM were also given. Numerical results indicate that the protected probability of radar in excursion link is larger than that in excursion equilateral triangle. Hence, the excursion link that antagonizes ARMs is effective and economical. © 2016 IEEE.
Huang W.,China Ship Development And Design Center
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2017
In terms of the uncertainty measurement and the constraint on the attitude quaternion, this paper proposes a quaternion constrained cubature Kalman filter based on uncertain measurements (UCCKF) for the spacecraft attitude estimation system. The proposed filter algorithm overcomes the limitation of the quaternion-constrained cubature Kalman filter. An independent Bernoulli random process is introduced to describe the measurement uncertainty, and the three degree spherical radial cubature rule is adopted to computer the posterior mean and covariance of the system state. To deal with quaternion normalization problem, the two-step projection theory is applied to solve the quaternion constraint. Simulation results show that, compared with constrained cubature Kalman filter and unscented mixture filter, the proposed UCCKF can help to implement the better convergence and higher estimation accuracy in the case of measurement uncertainty. This illustrates that the proposed algorithm is effective and feasible for the nonlinear attitude estimation system. © 2017, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.
Wu Z.,Peking University |
Chen G.Q.,Peking University |
Zeng L.,China Ship Development And Design Center
Ecological Modelling | Year: 2011
As an extension of the modelling on environmental dispersion in a single zone wetland [Zeng, L., Chen, G.Q., 2009. Ecological degradation and hydraulic dispersion of contaminant in wetland. Ecol. Model., 222, 293-300], the typical case of a pulsed contaminant emission into a steady flow through a distinctively vegetated two-zone shallow wetland channel is analytically explored in this paper in terms of the longitudinal evolution of the lateral mean concentration under environmental dispersion. The velocity profile of a fully developed flow through the wetland is derived, with that for a single zone wetland flow included as a special case. Taylor's classical analysis and Aris's method of concentration moments for solute dispersion in a single phase fluid flow are rigorously generalized for the two-zone case of a wetland flow to develop the dispersion model and to determine the dispersivity, which is illustrated with an asymptotic time variation characterized by stem dominated, transitional, and width-stem dominated stages. For typical contaminant constituents of chemical oxygen demand, biochemical oxygen demand, total phosphorus, total nitrogen and heavy metal, the evolution of contaminant cloud is illustrated with the critical length and duration of the contaminant cloud with constituent concentration beyond some given environmental standard level. © 2010 Elsevier B.V.
Niu M.,China Ship Development And Design Center |
Zang S.,Shanghai JiaoTong University
Experimental Thermal and Fluid Science | Year: 2011
This investigation presents detailed experimental measurements of an active tip-clearance control method based on tip injection in a high-turning axial turbine cascade. Besides that, numerical investigations are also conducted to study phenomena which are not easily measured in the experiments. It aims to study the influence of tip injection on tip clearance flow, with emphasis on the effects of injection locations. Detailed flow field measurements were made downstream of the cascade using a three-hole probe. Static pressure distributions were also measured on the blade surface at 50% and 97.5% span, respectively. The results suggest that tip injection can weaken tip clearance flow, reducing the tip clearance mass flow and its associated losses. Meanwhile, the heat transfer condition on the blade tip surface can be also improved significantly. It also can be found that injection chordwise location plays an important role in the redistribution of secondary flow within the cascade passage. When the same number of injection holes and injection mass flow are applied, holes located in the aft part of blade can perform much better than that in the front part. © 2011 Elsevier Inc.
Zhu Z.,China Ship Development And Design Center
Journal of Medical Systems | Year: 2012
To ensure patients' privacy, such as telephone number, medical record number, health information, etc.; authentication schemes for telecare medicine information systems (TMIS) have been studied widely. Recently, Wei et al. proposed an efficient authentication scheme for TMIS. They claimed their scheme could resist various attacks. However, in this paper, we will show their scheme is vulnerable to an off-line password guessing attack when user's smart card is lost. To improve the security, we propose a new authentication scheme for TMIS. The analysis shows our scheme could overcome the weaknesses in Wei et al.'s scheme and has better performance than their scheme. © 2012 Springer Science+Business Media, LLC.
Sun F.,Harbin Engineering University |
Tang L.-J.,China Ship Development And Design Center
Kongzhi yu Juece/Control and Decision | Year: 2013
In order to select the appropriate filtering method from the UKF and CKF for the different dimensions nonlinear systems estimation, the two filters are analyzed and compared through the Taylor expansion of function and the numerical stability. Due to the different dimension, the captured high-order item degree of function Taylor expansion and the numerical stability are different to appear different filter precisions, so that the filter choice ways of different dimension are acquired. Simulation results show the correctness of with the theoretical analysis.