中国开放科研知识云: 检索

Structural design of large aperture rectangular mirror for space telescope (EI CONFERENCE) 会议论文
2nd International Conference on Civil Engineering and Transportation, ICCET 2012, October 27, 2012 - October 28, 2012, Guilin, China
Li Z.

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Structural design of large aperture mirror is one of the key technologies for space telescope development. To meet the requirements of high stiffness strength and thermal dimensional stability some factors such as support scheme materials selection lightweight design and flexible support design were taken into account. The three supports location of the mirror was determined according to the modal analytical solution. By adjusting the parameters of flexure hinge influences of gravity assembly stress and thermal stress on the mirror were reduced obviously. Finite element analysis (FEA) results indicate that the surface accuracy reach to rms10.2nm and 10.8nm under the gravity along optical axis direction and 5C uniform temperature rise respectively the fundamental frequency of the mirror component is 268Hz. Dynamics test shows that the first order natural frequency is 256Hz which shows an error less than 5% compared to FEA results. (2013) Trans Tech Publications Switzerland.

Image mosaic technique based on the information of edge (EI CONFERENCE) 会议论文
2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012, July 31, 2012 - August 2, 2012, Guilin, Guangxi, China
Wu Z.-G.; Wang M.-J.; Wang Y.-Q.

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Image mosaic is an important branch in the field of image processing. This paper designs and realizes an image mosaic technique based on the information of edge. The technology is suitable for engineering application. First of all two images of the adjoining frames are processed by convolution operation get the edge images. And then we cut edge image into pieces and compute their spatial frequency. According to the value of the spatial frequency select reasonable registration model group. We compute correlation strength and the value of movement offset which are the model group and the current frame edge image. We can complete image mosaic by them. We use video sequence which of the resolution is 1024 * 768 do the experiment. The results show that the method has good effect and strong adaptability. Algorithm is high efficiency which running time is 24 ms. It is suitable for real-time processing requirements of the application. This method is an effective mosaic technique which is suitable for engineering application. 2012 IEEE.

Study on ultra-light secondary baffle for coaxial two-mirror telescope (EI CONFERENCE) 会议论文
2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012, August 5, 2012 - August 8, 2012, Chengdu, China
Zhang L.; Jia X.; Xie P.; Xing L.

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The coaxial two-mirror telescope consists of two mirrors facing each other. Classical two-mirror arrangements are Gregorian and Cassegrain. These systems are usually applied to space telescopes and often have optical baffles to prevent stray light from entering the focal plane. The optical baffles consist of concentric rings suspended between the secondary and the primary mirror. The secondary baffle for a large two-mirror optical system is designed and analyzed in this paper. According to mission of a telescope the structure should have high stiffness and high reliability and light weight. Compared with invar aluminum alloy and titanium alloy carbon fiber composite is currently the best material in terms of weight-to-strength ratio. It also has advantages of high temperature tolerance and low thermal expansion. So carbon fiber composite is chosen as material to meet requirements of the coaxial telescope. In this paper optimization method based on finite element analysis (FEA) is used for design the secondary baffle. Minimum weight of the baffle is chosen as an objective function. Thicknesses of former tube and vanes are chosen as variables. Analysis results show that the designed secondary baffle has maximum diameter of 180mm total length of 120mm and weighs 142g. And its fundamental frequency reaches 651Hz. Therefore the baffle has many advantages such as ultra-light weight high stiffness and dimensional stability etc. The optimization method and the baffle design can be helpful to other coaxial telescopes such as Cassegrain Gregorian and their subdivisions. 2012 IEEE.

Lightweight design and analysis of support structure of certain UAV engine (EI CONFERENCE) 会议论文
2012 International Conference on Electrical Insulating Materials and Electrical Engineering, EIMEE 2012, May 25, 2012 - May 27, 2012, Shenyang, Liaoning, China
Xing X.; Liu B.; Han X.; Jia H.

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Support structure of UAV (Unmanned Aerial Vehicle) engine is the important support for UAV engine playing a support role and bearing extremely complex load so its lightweight strength and dynamic characteristics have a great influence on high performance of UAV. This paper focuses on UAV having the requirement of high performance and stability to the support structure of engine and uses the software of MSC.Patran and MSC.Nastran and topology optimization criterion to lightweight design and analysis the support structure of UAV engine under the premise condition of existing constraints. Then the static strength and modal are analyzed for the result of lightweight design and the strength of the model and dynamic characteristics are verified. (2012) Trans Tech Publications Switzerland.

Research on defect detection technology of C/C composite (EI CONFERENCE) 会议论文
2011 International Conference on Advanced Engineering Materials and Technology, AEMT 2011, July 29, 2011 - July 31, 2011, Sanya, China
Zhao W.; Dong J.; Li W.; Wang H.; Guo Q.

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Carbon matrix/Carbon fibre reinforced composite(C/C composite) has many special characteristics such as high strength high elastic modulus high temperature resistance and ablation resistance. So it is used to manufacture rocket engine nozzle in aerospace filed. But its security will be seriously effected during rocket engine working due to the manufacturing defects. Based on analyzing defect types and structure characteristic of C/C composite the ultrasonic and infrared testing methods on C/C composite are further studied in this thesis. and effective defect detection has been achieved. (2011) Trans Tech Publications.

Surface shape optimization for the space membrane reflector (EI CONFERENCE) 会议论文
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
Zhang P.; Jin G.; Zhong X.; Zhang Y.; Qi Y.-C.; Jie P.

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Space membrane reflector is very promised for optical quality application with the merits of ultra-lightweight and flexible. In order to improve the surface precision of membrane reflectors the formation and surface shape error of a membrane at uniform load are studied based on the henky-cambell equations of circular membrane. The ANSYS software is used to build an optimization model of membrane reflector surface shape in which the yield strength is the state variable the surface load on ten concentric annular regions of the mirror is the design variable and the minimum RMS between ideal surface and mirror surface is the target function. and the theoretical and experimental result show that RMS and PV of the optimized surfaces are reduced respectively than those before optimization. In a word this paper offers the theoretical and experimental basis of the polyimide membrane reflector. 2011 IEEE.

Multi-focus image fusion algorithm based on adaptive PCNN and wavelet transform (EI CONFERENCE) 会议论文
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Wu Z.-G.; Wang M.-J.; Han G.-L.

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Being an efficient method of information fusion image fusion has been used in many fields such as machine vision medical diagnosis military applications and remote sensing.In this paper Pulse Coupled Neural Network (PCNN) is introduced in this research field for its interesting properties in image processing including segmentation target recognition et al. and a novel algorithm based on PCNN and Wavelet Transform for Multi-focus image fusion is proposed. First the two original images are decomposed by wavelet transform. Then based on the PCNN a fusion rule in the Wavelet domain is given. This algorithm uses the wavelet coefficient in each frequency domain as the linking strength so that its value can be chosen adaptively. Wavelet coefficients map to the range of image gray-scale. The output threshold function attenuates to minimum gray over time. Then all pixels of image get the ignition. So the output of PCNN in each iteration time is ignition wavelet coefficients of threshold strength in different time. At this moment the sequences of ignition of wavelet coefficients represent ignition timing of each neuron. The ignition timing of PCNN in each neuron is mapped to corresponding image gray-scale range which is a picture of ignition timing mapping. Then it can judge the targets in the neuron are obvious features or not obvious. The fusion coefficients are decided by the compare-selection operator with the firing time gradient maps and the fusion image is reconstructed by wavelet inverse transform. Furthermore by this algorithm the threshold adjusting constant is estimated by appointed iteration number. Furthermore In order to sufficient reflect order of the firing time the threshold adjusting constant is estimated by appointed iteration number. So after the iteration achieved each of the wavelet coefficient is activated. In order to verify the effectiveness of proposed rules the experiments upon Multi-focus image are done. Moreover comparative results of evaluating fusion quality are listed. The experimental results show that the method can effectively enhance the edge details and improve the spatial resolution of the image. 2011 SPIE.

Study of the neural network constitutive models for turfy soil with different decomposition degree (EI CONFERENCE) 会议论文
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
Lv Y.; Nie L.; Xu K.

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The turfy soil is of a special humus soil. The decomposition degree is the main factor on the physical and mechanical properties of turfy soil. To build the turfy soil constitutive model there are a few shortages such as the calculation cumbersome and low accuracy for parameter value with the method of traditional models. Furthermore those methods did not reflect the influence of strength that effected by decomposition degree of the turfy soil. In this paper the relationship of stress-strain with different decomposition degrees of turfy soil was carried out through indoor tests. Based on above experimental results an improved method which divided into different zones according to different decomposition degrees of turfy soil and calculated combining with neural network constitutive model is put forward. The result shows that the neural network of turfy soil has good fitting precision and good generalization ability. It can fully describe the influence of the turfy soil. 2011 IEEE.

Optimum design of the carbon fiber thin-walled baffle for the space-based camera (EI CONFERENCE) 会议论文
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Yan Y.; Gu S.; An Y.; Jin G.

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The thin-walled baffle design of the space-based camera is an important job in the lightweight space camera research task for its stringent quality requirement and harsh mechanical environment especially for the thin-walled baffle of the carbon fiber design. In the paper an especially thin-walled baffle of the carbon fiber design process was described and it is sound significant during the other thin-walled baffle design of the space camera. The designer obtained the design margin of the thin-walled baffle that structural stiffness and strength can tolerated belong to its development requirements through the appropriate use of the finite element analysis of the walled parameters influence sensitivity to its structural stiffness and strength. And the designer can determine the better optimization criterion of thin-walled baffle during the geometric parameter optimization process in such guiding principle. It sounds significant during the optimum design of the thin-walled baffle of the space camera. For structural stiffness and strength of the carbon fibers structure which can been designed the effect of the optimization will be more remarkable though the optional design of the parameters chose. Combination of manufacture process and design requirements the paper completed the thin-walled baffle structure scheme selection and optimized the specific carbon fiber fabrication technology though the FEM optimization and the processing cost and process cycle are retrenchment/saved effectively in the method. Meanwhile the weight of the thin-walled baffle reduced significantly in meet the design requirements under the premise of the structure. The engineering prediction had been adopted and the related result shows that the thin-walled baffle satisfied the space-based camera engineering practical needs very well its quality reduced about 20% the final assessment index of the thin-walled baffle were superior to the overall design requirements significantly. The design method is reasonable and efficient to the other thin-walled baffle that mass and work environment requirement is requirement harsh. 2011 SPIE.

Thermal-structure analysis of supersonic dome based on three materials (EI CONFERENCE) 会议论文
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
Jiang Z.; Ai X.; Wei Q.; Liu B.; Jia H.

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To a supersonic missile a seeker could enhance the aerodynamic ability due to decrease the resistance in flying. At the same time the primary function of a seeker has been considered as the most important equipment for a missile due to the importance for cueing of targets and tracking for the final approach. However the dome of a seeker which is made up of glass has poor mechanical performance. Especially in the higher altitude for a dome in which the aerothermal and pressure loads could destroy the structure easily it is necessary to do the thermal-structure coupled analysis due to varied materials. In the paper to take the spherical dome of a seeker as a example the analysis has been completed according to the varied materials consist of MgF2 Al2O3 and ZnS. The temperature loads and the pressure loads derived from the results of fluent analysis has been forced on the surface of dome which simulates the actual Mach 2.5 in flying. According to the results of coupled analysis the SEQV stress of the dome radium 80mm based on three materials had reached to 31MPa which shows that the strength is sufficient for Mach 2.5 and offered the warranty to design the attaching to missile for the dome. At the same time the results required the flexible mounting for the dome due to the displacements results which the crystal material couldn't accept. 2011 IEEE.

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