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Xia G.,Nanjing University of Science and Technology | Sun H.,Nanjing University of Science and Technology | Niu X.,Nanjing Chenguang Group Corporation | Zhang G.,Nanjing University of Science and Technology | Feng L.,Nanjing University of Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2017

Human motion capture data, which are used to animate animation characters, have been widely used in many areas. To satisfy the high-precision requirement, human motion data are captured with a high frequency (120 frames/s) by a high-precision capture system. However, the high frequency and nonlinear structure make the storage, retrieval, and browsing of motion data challenging problems, which can be solved by keyframe extraction. Current keyframe extraction methods do not properly model two important characteristics of motion data, i.e., sparseness and Riemannian manifold structure. Therefore, we propose a new model called joint kernel sparse representation (SR), which is in marked contrast to all current keyframe extraction methods for motion data and can simultaneously model the sparseness and the Riemannian manifold structure. The proposed model completes the SR in a kernel-induced space with a geodesic exponential kernel, whereas the traditional SR cannot model the nonlinear structure of motion data in the Euclidean space. Meanwhile, because of several important modifications to traditional SR, our model can also exploit the relations between joints and solve two problems, i.e., the unreasonable distribution and redundancy of extracted keyframes, which current methods do not solve. Extensive experiments demonstrate the effectiveness of the proposed method. © 1982-2012 IEEE.

Dai W.,Beihang University | Lian Y.,Beihang University | Xiao J.,Beihang University | Luo G.,Nanjing Chenguang Group Co.
Proceedings of 2015 the 1st International Conference on Reliability Systems Engineering, ICRSE 2015 | Year: 2015

This paper develops a series of standardized procedures and improvements specific to inefficiency of domestic process reliability research by analyzing problems existing in process optimization of some current model. Firstly, weak links are identified through theoretical analyses including process FMECA. Secondly, mechanisms of process defects and critical stress are acquired by constructing physics model of failures, during which optimization measures need to be proposed. Finally, the optimization measures should be verified by the combination of theoretical analyses and FEA. The results should be subsequently applied to design and manufacture if approved. Demonstrated by tests, the standardized procedures is able to effectively identify critical stress and defects, making optimization more scientific and consequently improving efficiency. © 2015 IEEE.

Chu J.,Beihang University | Dai W.,Beihang University | An J.,China Nuclear Power Engineering Co. | Yong S.-R.,Nanjing Chenguang Group Co. | Zhao Y.,Beihang University
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS | Year: 2015

To improve the mission reliability of the manufacturing process and to quantitatively represent the changes of basic reliability and mission reliability in different rework strategies, a rework model based on stress-strength interference theory was built up. Through statistically analyzing the large amounts of historical data produced from the actual process, the function between reliability and mission payload could be simulated. The mission reliability and unit costs of each rework strategy based on the rework model were calculated under the given input quantities. Each rework strategy could be analyzed by calculating with the weighted decision value, and then the best rework strategy was found. An application case was used to prove the correctness of the method. ©, 2015, CIMS. All right reserved.

Xu X.,Nanjing Chenguang Group Co. | Sun Y.,Nanjing University of Science and Technology | Jiang Q.,Nanjing University of Science and Technology
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2013

When film was winding, the tension and the stability had a decisive impact on the winding quality. According to the dynamic process of the winding system of a casting machine, the dynamic relationships among tension and speed, radius, rotate speed were analyzed, the principles of tension control were proposed, and the compensation law of the rotaty speed was calculated when the radius was increasing and the winding roller was shifting. Based on the models, a tension control system was designed. The tension was controlled indirectly by controlling the difference of speed, and was controlled directly by using BP neural network PID controller to adjust the motor speed. Simulation results show that the controller has a good dynamic response and the anti-jamming ability. In practice, it also proves that the control system is feasible. It has a high precision of tension control and has great significance to improve the dynamic performance of the system and the winding quality of the film.

Zheng H.P.,Hebei University of Science and Technology | Chen L.,Hebei University of Science and Technology | Wang W.,Nanjing Chenguang Group Co. | Peng L.Q.,Hebei University of Science and Technology | Zhang J.Y.,Hebei University of Science and Technology
Applied Mechanics and Materials | Year: 2014

Vibratory pile driving is a common application method of piles foundation construction. A test bed was designed and built according to the principle of vibratory pile driving. The test bed is composed of excitation system, machinery parts and signal acquisition system. At first soil samples with different relative compactness and different saturation were made. Then tests of vibratory pile driving have been done by using the soil samples and the test bed. For each soil sample, time of pile sinking to the bottom of the container was recorded respectively under the condition of the exciting force with same amplitude. The time represents efficiency of vibratory pile driving. The former is shorter and the latter is higher. Relationships between efficiency of vibratory pile driving and exciting frequency, relative compactness of soil, saturation of soil were researched respectively by single factor method. The experimental results have guide meaning to vibratory pile driving construction. © (2014) Trans Tech Publications, Switzerland.

Zhang D.,Nanjing University of Aeronautics and Astronautics | Zuo D.,Nanjing University of Aeronautics and Astronautics | Jiao G.,Nanjing University of Aeronautics and Astronautics | Jiao G.,Nanjing Chenguang Group Co. | And 3 more authors.
Key Engineering Materials | Year: 2010

According to the characteristics of aerospace product, the model representation and storage of the rigid part and cable harness is proposed. The Dendritic Correlative Model of Mixed Assembly of Rigid and Flexible Parts (DCMMA-RFP) is introduced based on the hierarchical model and graph model. The assembly model which realizes the lightweight storage can clearly represent the hierarchy relation and assembly process of aerospace products. The assembly modeling process in the virtual assembly environment is detailed described. Finally the effectiveness of DCMMA-RFP is verified by an example.

Yan J.,Nanjing University of Aeronautics and Astronautics | Xie J.,Nanjing University of Aeronautics and Astronautics | Li J.P.,Nanjing Chenguang Group Co. | Zhang D.,Nanjing University of Aeronautics and Astronautics | Zuo D.W.,Nanjing University of Aeronautics and Astronautics
Key Engineering Materials | Year: 2010

A kind of model oriented assembly process simulation in WTK environment has been proposed. In the model, firstly, the assembly hierarchy of mechanical products can be presented clearly. Secondly, the assembly constraints between parts can be added to the model easily. At last, the assembly process information such as assembly sequence and path for each part can be recorded at real time in the model. Then, the converted method from PRO/E system to WTK environment about the mechanical product's design information including geometric models, product design hierarchies and constraints has been discussed, which makes for easier building the model in the virtual environment.

Wang H.-M.,Nanjing University of Science and Technology | Wang H.-M.,No208 Research Institute Of China Ordnance Industries | Chen X.,Nanjing University of Science and Technology | Zhao C.,Nanjing University of Science and Technology | And 2 more authors.
Tuijin Jishu/Journal of Propulsion Technology | Year: 2015

Using CO2 laser, high-speed camera and IR thermograph, the ignition and combustion process and the surface temperature distribution of NEPE propellant under laser irradiation were studied. The influence of laser heat flux on the ignition delay time and the dynamic response of NEPE propellant after unloading laser were analyzed. Results show that the ignition delay time tends to decrease with the increase of laser heat flux. When the heat flux is less than 6.7×105W·m-2, the ignition delay time decreases fast with the increase of laser heat flux, but varies little when the heat flux is greater than this value. Laser irradiation had a significant effect on the combustion of NEPE propellant, the brighter flame, the more sparks and the higher temperature of the propellant surface are presented. After the laser unloading, the surface temperature of the propellant does not decline immediately, but falls rapidly after a short delay, and then shows a small rise slowly. ©, 2015, Tuijin Jishu/Journal of Propulsion Technology. All right reserved.

Chen X.,Nanjing University of Science and Technology | Zhu G.-Q.,Nanjing Chenguang Group Co. | Zheng J.,Nanjing University of Science and Technology
Binggong Xuebao/Acta Armamentarii | Year: 2015

Numerical simulation and direct connected test methods are used to study the influences of selected factors on the fuel surface regression rate of polymethylmethacrylate (PMMA) in a solid fuel ramjet. The influences of air mass flux and fuel internal diameter on the solid fuel average regression rate and local regression rate are studied. The results show that the temperature, heat flux and local regression rate of the solid fuel surface firstly increase and then decrease gradually along the axial direction, and reach the maximum values at the reattachment point in the end of the recirculation zone. The local regression rate of the fuel surface increases with the inner radius of fuel, but decreases with the mass flux of the air. The average regression rate of the fuel shows an increasing power function relation with air mass flux and a decreasing power function relation with fuel internal diameter. The numerical simulation results are coincident with the experimental results, and are slightly larger than experimental results. The maximum error is less than 10%. © 2015, China Ordnance Society. All right reserved.

Zhang D.,Nanjing University of Aeronautics and Astronautics | Zuo D.-W.,Nanjing University of Aeronautics and Astronautics | Jiao G.-M.,Nanjing University of Aeronautics and Astronautics | Yan J.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Jisuanji Jicheng Zhizao Xitong/Computer Integrated Manufacturing Systems, CIMS | Year: 2010

To ensure the precision and efficiency of virtual assembly operations, a novel assembly intention capturing algorithm was proposed. The expression of constraint model and modeling method in virtual assembly environment were presented. The concept of Constraint Element Bounding Box(CEBB)was introduced and its construction rules and method were also put forward. Intersection test between two CEBB was used as the portal of assembly intention capturing algorithm. Constraints multi-layer recognition rules were presented to define the constraint type based on the mapping relationship between constraint elements and degree of freedom. Then, to realize the intelligent constraint confirmation, constraint priority and comparison strategy of motion increment between constraint elements were proposed. The time cost function was introduced to estimate the computation efficiency of the algorithm. Finally, effectiveness of the proposed method was verified by an application example in an aerospace product.

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