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2014 Vol. 40, No. 7

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Statics and stiffness of 3 DOF parallel loading mechanism
Fan Rui, Liu Huan, Wang Dan
2014, 40(7): 861-866. doi: 10.13700/j.bh.1001-5965.2013.0491
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A static model of a 3-DOF parallel mechanism (PM) that is used for computerized numerical control (CNC) machine tool follow-up loading test was established based on the screw theory. The mapping between actuation force and loading force of the moving platform was built considering the influence of limbs' weight. Then the distribution of actuation forces in workspace under specified loads was analyzed through a numerical example. Moreover, the static stiffness mapping model of the PM was established. The model considers influences of the limbs' weight and the parts' elastic deformation under the constraint force. At last the deformation of the PM in the workspace under given static loads was analyzed and the stiffness characteristic was evaluated. The results show that the distribution of stiffness in workspace is symmetrical about the y-axis and the stiffness will be worsened when it comes near the workspace boundary.
Stress corrosion properties of 00Cr18Ni10N austenitic stainless steel welded joints
Liu Jianhua, Wang Bing, Li Songmei, Yu Mei
2014, 40(7): 867-872. doi: 10.13700/j.bh.1001-5965.2013.0474
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The behaviors of stress corrosion cracking of an austenitic stainless 00Cr18Ni10N parent material and its welded joint in 3.5% NaCl solution were investigated by using the constant load stress corrosion cracking and microscopic analysis methods. The residual strength was measured after 120 h for stress corrosion test to compare the stress corrosion resistance of 00Cr18Ni10N parent material and its welded joint through the loss analysis of strength. The microstructures of the weld zone, heat affected zone and base metal were analyzed by metallographic technique, and fracture morphology of stress corrosion cracking was investigated using scanning electron microscopy. The results show stress corrosion cracking of welded joints is located in the weld zone. A higher stress level 90% σ0.2, the strength lose of 00Cr18Ni10N parent material is 13.02% lower than that of the welded joints, which show that the stress corrosion resistance of 00Cr18Ni10N parent material is superior to the weld material. The fracture morphology analysis shows that the fracture of 00Cr18Ni10N parent material and its welded joint has the characteristic of intergranular fracture and dimple fracture under the joint action of stress and corrosive solution.
Electromechanical coupled dynamic characteristics of the plate with piezoelectric network
Li Lin, Yi Kaijun
2014, 40(7): 873-880. doi: 10.13700/j.bh.1001-5965.2013.0501
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Electromechanical coupled dynamic equations of the plate with piezoelectric network were established which was based on homogenization method of modeling composite structure. The characteristic equation of this coupled system was obtained by solving the dynamic equations. Through solving the characteristic equations it is found that the nature modes of the system always appear in coupled pairs, and the varying of frequencies corresponding to the coupled modal pairs with the inductance has a veer. Further analysis on the energy exchange in frequency veering zones of the system gave the mechanism of the frequency veering phenomena. At last, impacts of design parameters to frequency veering zones were studied, which provides theoretical reference for reasonable design of the plate with piezoelectric network.
Mechanical properties evaluation based on least squares for actuators system
Zhang Yeming, Cai Maolin
2014, 40(7): 881-886. doi: 10.13700/j.bh.1001-5965.2013.0493
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The advantages and disadvantages of mechanical properties evaluation methods were analyzed. The main evaluation factors of mechanical properties of pneumatic and electric actuators system were given, and three ways of acquiring actuator system evaluation factor data were listed. A method of mechanical properties combination weight evaluation for actuator systems based on least squares was proposed. Firstly, two kinds of attribute weights of actuators system mechanical properties were obtained with information entropy theory and analytic hierarchy process (AHP) theory. Then the combination weights of actuators system were obtained with least squares method, and the comprehensive evaluation values of actuators system were calculated for selecting the most excellent solution. Finally the new evaluation method authentication was carried out with the specific examples. Results show that, as a case of pneumatic and electric actuators system under the specific conditions, the mechanical properties of pneumatic actuator system are better than that of electric actuator system with the combination weight mechanical properties evaluation method, and the result fits the on-site conditions. The standard deviation of the new method for actuators system is smaller than that of information entropy and AHP-fuzzy comprehensive evaluation (AHP-FCE).
Adaptive parameter generation in terrain reconstruction with descent images
Meng Cai, Zhou Na, Zhang Yani
2014, 40(7): 887-892. doi: 10.13700/j.bh.1001-5965.2013.0464
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In homography based landing area terrain reconstruction with descent images, the reconstruction parameters greatly influence the reconstruction results. Therefore a method for adaptive parameter generation was proposed to find the best parameters automatically. Firstly, an approximate terrain plane was fitted by the spatial points which were determined by the matched feature points in the descent images. The fitted terrain plane worked as the reference plane of the series of parallel slices and determined the normal vector and basic depth. Secondly, at both sides of the fitted terrain plane, the furthest distances between the 3D points and the fitted terrain plane were calculated separately, and thus the terrain height difference could be reckoned. At last, the best account of virtual slice planes was determined with the terrain height difference and the basic depth information of the fitted terrain plane. Through these steps, the homographies which were needed to recover the terrain of landing area could be worked out by these parameters. The comparison of reconstruction results of different parameters shows that the parameters obtained by the proposed method can lead to better reconstruction results without redundant calculation burden.
Thermal characteristic of aerostatic direct-driven rotary stage
Zhang Congpeng, Liu Tong, Li Meibo
2014, 40(7): 893-898. doi: 10.13700/j.bh.1001-5965.2013.0771
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In order to develop a precision aerostatic direct-driven rotary stage for precision engineering application, the thermal structure stability and forced cooling method were investigated. First, the heat generation and heat transfer characteristics of this aerostatic direct-driven rotary stage were analyzed, and finite element model of thermal characteristics was set up. The temperature field distribution in the aerostatic direct-driven rotary table was obtained. Then, according to the indirect coupling analysis method, the thermal-structural coupling deformation of the rotary stage was calculated by taking the temperature field as loading conditions. Next, through comparing thermal deformation, the aerostatic direct-driven rotary stage structure thermal stability was discussed, and an air forced convection cooling method and the gas circuit design were provided. Finally, temperature field distribution test experiments were carried out. Experimental results indicate that temperature field distribution calculator precision is high, and maximum bias of the finite element calculation is 1.93 ℃, and the air film thickness change of the thrust air bearing is less than 0.55 μm which is within the permitted range and has no effect on air bearing performance. The rear-motor aerostatic direct-driven rotary stage has good thermal stability and is suitable for industrial application.
Identification method of failure mechanism consistency by non-equidistance grey theory model
Li Xiaogang, Wang Yahui
2014, 40(7): 899-904. doi: 10.13700/j.bh.1001-5965.2013.0483
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To deal with the problems of accelerated failure mechanism consistency identification in the methods based on data processing and experimental observation need the accelerated testing data and the method based on grey theory needs that the data of pre-test is equidistant as well as the prediction accuracy is not high, a new method of failure mechanism consistency identification based on non-equidistance grey theory model was proposed. The method combined the non-equidistance GM (1, 1) with equal dimension model by the non-equidistance pre-test data, got the residual, and found the change point of trend of data from pre-test. According to the contrast test, the method of fitting precision and prediction precision was higher, and the application scope of GM (1, 1) model in the failure mechanism consistency identification was enlarged. Finally, the effectiveness of the method was validated by a practical example on photoelectric encoder and accelerometer.
Optimal multi-impulse rendezvous based on T-H equations
Ji Xiaoqin, Xiao Lihong, Chen Wenhui
2014, 40(7): 905-909. doi: 10.13700/j.bh.1001-5965.2013.0488
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For rendezvous near an elliptic reference orbit, relative motion was described by T-H equations. One time-fixed fuel-optimum multi-impulse rendezvous method was proposed to determine the optimal impulse and its time. If J2 perturbation or the far initial relative distance was considered, the T-H equations linearization error couldn't be ignored, while the trajectory integration was more time-consuming and the optimal convergence rate decreased. For this problem, a new method was put forward that the current node state could be predicted with the orbit element computed by the previous one. It was very simple and valid for making optimal convergence faster. Based on the optimal impulse time, the trajectory numerical integration was carried out to verify the rendezvous precision. The results indicate that the terminal position has higher accuracy up to 75 m even under J2 perturbation and the initial relative distance of 1 000 km.
Optimization of lunar soft landing trajectory based on hybrid method
Peng Kun, Guo Linli, Xiang Kaiheng, Wang Ping, Xu Shijie
2014, 40(7): 910-915. doi: 10.13700/j.bh.1001-5965.2013.0710
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The lunar soft landing trajectory was optimized by hybrid method and artificial immune algorithm (AIA). Firstly, the system model of lunar soft landing trajectory was established and normalized. Secondly, the optimization problem of lunar soft landing trajectory was converted into a nonlinear programming (NLP) via hybrid method, in which optimal control law was derived by Pontryagin's maximum principle, the initial values of adjoint variables and terminal time were variables to be optimized, and terminal constraints were introduced into evaluation function as penalty terms. Finally, a guiding artificial immune algorithm (GAIA) was applied to solve this optimization problem. Simulation results show that the GAIA hybrid method has faster optimization speed and higher optimization precision than direct method, and can obtain the theoretical optimal trajectory. Meanwhile, GAIA hybrid method has larger convergence range of initial value of adjoint variables than indirect method, and reduces the difficulty of searching optimal lunar soft landing trajectory.
Experimental analysis on micro-Doppler characteristics of rotors
Wang Ying, Peng Yaokun, Liu Feiliang, Huang Peilin, Ji Jinzu
2014, 40(7): 916-920. doi: 10.13700/j.bh.1001-5965.2013.0486
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In order to analyze the micro-Doppler effect of rotor and its main parts, a measurement method using microwave anechoic chamber was suggested, and its reliability was verified by some examples. A series of experiments on some rotors with two kinds of blades and with different numbers of blades indicate that echoes of various scattering components can be separated by frequency in the micro-Doppler effect. The number of blades and the rotation speed of rotor do not affect the analysis and estimate of the micro-Doppler effect. It can also be concluded that the micro-Doppler effect only depends on the motion characteristic of the rotor. Combined with target characteristics of helicopter, micro-Doppler effect of rotor was extracted from experimental data using short fast Fourier transform, and the frequency characteristic, wide frequency band and polarization characteristic were obtained by analyzing the influences of incident wave and geometry characteristics of rotor on micro-Doppler effect.
Numerical method of forward position solution for 6-3 Stewart platform based on mechanism simplification
Xue Jian, Tang Zhiyong, Pei Zhongcai
2014, 40(7): 921-926. doi: 10.13700/j.bh.1001-5965.2013.0492
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To increase the speed of forward position solution for Stewart platform, the classical iterative method based on speed Jacobian was analyzed, and the new method for 6-3 Stewart platform was proposed. 6-3 Stewart platform was simplified as virtual 3-RPS parallel mechanism and its forward position solution was obtained by Newton-Raphson method. The result was solved back to the pose of actual platform. Experimental results on self-designed hydraulic 6-3 Stewart platform system present that, compared with classical method, the new one reduced nearly 50% of iterations and about 85% of time cost for solution. The concept of the new method is clear, mechanism simplification is easy implementing, and the computational cost of forward position solution for simplified 3-RPS parallel mechanism is significantly decreased. The new method is capable for forward position solution in a real-time control with 0.1 ms control cycle.
Structural finite element model updating based on response surface optimization
Bao Nuo, Wang Chunjie
2014, 40(7): 927-933. doi: 10.13700/j.bh.1001-5965.2013.0525
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In order to solve the low accuracy problem in structural finite element analysis, a model updating method of surface response optimization was proposed. The sample points acquired by optimal Latin hypercube experimental design and the F-test evaluation utilized for parameter selection were used to construct the polynomial response surface model, and then the validity of response surface was tested. The residual error of the results between response surface and experiment was taken as the objective function. The genetic algorithm was employed to optimize the updating parameters. The updated model was obtained by substituting updated parameters into initial finite element model (FEM). The ability of the model updating methodology was proved under three working conditions, accurate parameters, no parameters and inaccurate parameters by the three degree-of-freedom numerical model. The model of GARTEUR was taken as an example. Significant parameters were selected out to implement the model updating. The results show that it not only proves the reappearance and prediction ability of the updated FEM, but also shows the ability to predict the modal frequency of locally modified structures, and verifies the validity of the model updating methodology.
Dynamic viscosity measurements of aviation hydrocarbon fuel RP-3 at sub-critical pressures
Jia Zhouxia, Xu Guoqiang, Deng Hongwu, Wen Jie
2014, 40(7): 934-938. doi: 10.13700/j.bh.1001-5965.2013.0456
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A new experimental method and apparatus were developed for the measurements of dynamic viscosity of fluids under high temperature and high pressure conditions based on classical capillary tube method. This method has an uncertainty of 1.009% according to the error analysis. Validation experiments were performed to measure the viscosity of distilled water (2 MPa, 290-400 K). The test results demonstrate that the average absolute deviation (AAD) is below 0.715%, and the maximum absolute deviation (MAD) is 2.3%. And then the dynamic viscosity of aviation kerosene RP-3 was measured under 298-755 K and 0.1-2 MPa. This method can be applied to any homogeneous Newtonian fluids.
Analysis on repeater jamming active cancellation for linear frequency modulated wave
Chen Shichun, Huang Peilin, Ji Jinzu
2014, 40(7): 939-946. doi: 10.13700/j.bh.1001-5965.2013.0457
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A repeater jamming active cancellation method for linear frequency modulated (LFM) wave was proposed. Utilizing the coupling between time delay and frequency shift of matched filtering output, by phase and frequency modulating, the synthetizing output of cancellation and original wave can meet the cancellation conditions on time, amplitude and phase, consequently the filtering output decreases as well as the detection probability. Formulae for the output of the phase-only modulated wave and phase and frequency modulated wave were derived. Filtering output characteristics were analyzed theoretically. Simulation results show that, for the phase-only modulated wave, the cancellation effect is proportional to the product of repeating time delay and wave bandwidth, decrease of which resulting in a better cancellation effect but a higher demand on the accuracy of phase and amplitude controlling. For the phase and frequency modulated wave, the cancellation effect is decided by the division of repeating time delay and pulse width. Bandwidth of the wave has no influence on the cancellation effect. A wider bandwidth needs a higher accuracy of the frequency modulating.
Aerodynamic design of micro radial inflow turbine with wall heat transfer
Ding Chao, Bian Lei, Zou Zhengping
2014, 40(7): 947-952. doi: 10.13700/j.bh.1001-5965.2013.0490
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The heat transfer effect is a significant difference between the micro radial inflow turbine and the conventional radial inflow turbine, so it is very important to take the wall heat transfer effect into consideration when designing a micro radial inflow turbine. Based on the feature of non-adiabatic wall in the micro radial inflow turbine, and through theoretical analysis, a velocity diagram analytical model was obtained preliminarily. On that basis, the aerodynamic design method of the micro radial inflow turbine was developed. Then the design rule of the micro radial inflow turbine considering wall heat transfer effect was summarized. Finally a three-dimensional numerical simulation was carried out to verify the obtained model and design method. Results show that the model and design method of the micro radial inflow turbine considering wall heat transfer effect is feasible.
Numerical method of aeroelasticity based on radial basis function interpolation
Lin Yanzhong, Chen Bing, Xu Xu
2014, 40(7): 953-958. doi: 10.13700/j.bh.1001-5965.2013.0460
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Proper and effective means of moving mesh and data exchange are the key points for aeroelasticity analysis. Radial basis function interpolation was introduced and used for aeroelasticity simulation, and the way how it was used in mesh deformation and data exchange was proposed. A computational method coupling computational fluid dynamics (CFD) and computational structure dynamics (CSD) was employed in solving the AGARD 445.6 wing flutter problem. In order to obtain different vibration phenomena including amplitude attenuation, equal amplitude resonance and amplitude increase, solutions under several upper stream velocity conditions were computed. Flutter speed and flutter frequency results are both in accordance with experimental data, which means that the radial basis function interpolation method is valid and can be used in aeroelasticity analysis.
Algorithm of structural topology optimization under loading uncertainty
Zhao Junpeng, Wang Chunjie
2014, 40(7): 959-964. doi: 10.13700/j.bh.1001-5965.2013.0476
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Structural topology optimization under loading uncertainty was studied, where the uncertainty was described by the probabilistic approach. According to the superposition principle of linear theory, computational method for expected and variance of structural compliance was proposed. Sensitivity analysis method was developed based on the expressions of the expected and variance of compliance. For 2D cases, the expected compliance and variance of structures as well as sensitivity information can be obtained by solving the equilibrium equation under 2n deterministic load cases, where n is the number of uncertain loads. Algorithm of structural topology optimization to minimize the weighted sum of expectation and standard deviation of compliance was proposed and verified by numerical examples. The numerical examples also demonstrate the robustness of topology optimization results under loading uncertainty. The proposed algorithm can be readily generalized into 3D cases.
Dynamic index based method for multi-objective optimization in aircraft conceptual design
Xu Min, Huang Peilin, Yan Ying, Li Wuzhou
2014, 40(7): 965-969. doi: 10.13700/j.bh.1001-5965.2013.0447
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To increase the search efficiency of optimal solution in aircraft conceptual design multi-objective optimization, comparison evaluation technique for multi-objective model was studied along with the implementation. Index benchmark (IB) was proposed for multi-objective model comparison, and dynamic index (DI) was conducted by updating the IB with the objective value of new solutions. Then multi-objective genetic algorithm (MOGA) was improved through conducting the fitness model with DI. The results of some optimization with two objectives indicate that better Pareto front can be obtained through the improved algorithm. Finally, the improved MOGA with DI (DIMOGA) was used in the multi-objective optimization of a light fighter conceptual design, including four optimal objectives in discipline on weight, aerodynamic, and stealth. The optimization results validate the effectiveness of DIMOGA method in the aircraft conceptual design optimization.
Vibration model of coilable mast considering slack diagonals
Han Jianbin, Huang Hai, Ma Haibo
2014, 40(7): 970-977. doi: 10.13700/j.bh.1001-5965.2013.0450
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After the coilable mast deploying, the battens are curved and the diagonals are tensioned because of the preload. The diagonals can be slack for large amplitude vibration. A vibration model was constructed to describe the fundamental frequency characteristic of that status. The curved batten and slack of diagonals was considered. The batten with small stiffness in curved status and preload was simulated with a rod with small elastic modulus and corresponding strain, and one rod element was modeled to simulate two cables which slacked in different time. The coilable mast before and after diagonals slack was treated as two different structures, and their finite element method (FEM) models were constructed with Ansys. Two fundamental frequencies were computed. Then the coilable mast was equivalent to a continuous beam with pricewise linear stiffness, the pricewise stiffness correspond to the different structure before and after the diagonals slack. Considering the criterion of diagonals slack obtained with that FEM model, the vibration equation of coilable mast with large amplitude was established. Using equivalent linearization method, the relationship between equivalent frequency of coilable mast and the top-end amplitude can be obtained. The result can be verified with transient analysis of Ansys. The model and result is helpful for the design and vibration control of coilable mast.
Effect of Reynolds number on characteristics of separated shear layer transition of backward facing step
Zhou Ning, Ze Cheng, Pan Chong
2014, 40(7): 978-983. doi: 10.13700/j.bh.1001-5965.2013.0481
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The backward-facing step flow is a classical model for the investigation of shear layer separation and reattachment characteristics. The transitional shear layer and its Re dependence was discussed by using two-dimensional time-resolved particle image velocimetry (PIV) measurement. It was observed that the location of reattachment point moves upstream if Re increases, while the transition point of the shear layer moves forward at the same time, leading to the dimensionless reattachment length inversely proportional to Re. In addition, before the transition occurs, the perturbation contained within the shear layer presents initial exponential growth, whose spatial growth rate is positively correlated with Re.
Excitation order verification of bladed-disk coupled resonance condition
Qi Zheng, Wang Jianjun
2014, 40(7): 984-987. doi: 10.13700/j.bh.1001-5965.2013.0455
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In order to define the influence factors of excitation order in bladed-disk coupling resonance condition, the image description of excitation order applied on bladed-disk structure under rotor-stator interference was given firstly. Then the new formula of excitation order was performed according to the similarity of excitation order image description and aliasing image description in sampling problem. Finally verification of excitation order formula was given both numerically and experimentally using a simple experimental bladed-disk model. The results show that under rotor-stator interaction the excitation order applied on bladed-disk structure is equal to the absolute value of the difference between stator vane number and an integral multiple rotor blade number which is the one nearest to stator vane number and the excitation order only relates to the blade number of rotor-stator. The bladed-disk coupling resonance also appears even if the stator vane number is more than the half of the rotor blade number.
Design and experiment of adjusting mechanism in aviation drilling end effector
Wang Qishen, Yuan Peijiang, Wang Tianmiao, Wang Chengkun
2014, 40(7): 988-993. doi: 10.13700/j.bh.1001-5965.2013.0471
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Aiming at the robot drilling perpendicularity in aircraft assembly, an adjusting attitude mechanism was designed using double eccentric discs. First, the normal at the drilling point was measured by four laser range sensors and the intersection point of the normal and the adjusting plane was calculated. Then the angles of eccentric discs should be rotated can be obtained and adjusting motors drived the mechanism to adjust the drill's attitude. The trait of the mechanism is that the drill's point can keep static when adjusting the drill's attitude. Thus, it can be avoided to remove the drill's point position. A model was simulated in ADAMS and a drilling experiment was done on a robot drilling system and both the results prove the principle of adjusting attitude mechanism.
Novel design for deeply integrated GPS/INS navigation system
Mo Fan, Wang Xinlong
2014, 40(7): 994-1000. doi: 10.13700/j.bh.1001-5965.2013.0489
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In order to enhance the tracking performance and navigation accuracy in high-dynamic and severe jamming conditions, a new deeply integrated navigation scheme of strapdown inertial navigation system/global positioning system (SINS/GPS) based on vector tracking was proposed. This scheme utilized the feedback loop of integrated Kalman filter to replace the independent and parallel tracking loops in traditional receivers, which enabled GPS receivers accomplish the tasks of available GPS satellite signals tracking and integrated navigation information processing synchronously. Vector tracking algorithm was used to enhance the correlations of tracking channels and strengthen the adaptability of changes of carrier-to-noise power density ratio (C/N0) for tracking channels, so that it could improve navigation performance during brief signal outage. This deeply integrated system treated the Is and Qs measurements as the measurements of the navigation filter directly, which could decrease residual errors of the filter and improve the navigation accuracy and tracking performance of this navigation system. The simulation results indicate that this deep integration scheme based on vector tracking could not only guarantee the navigation precision and reliability of the integrated system during brief signal outage, but also improve perfect tracking performance and anti-jamming capability at low (C/N0) level.
Simulation of voltage doubling rectifying circuit in 150 kV high-voltage inverter power supply
Du Huicong, Liu Fangjun, Zhang Wei, Zhao Jing
2014, 40(7): 1001-1005. doi: 10.13700/j.bh.1001-5965.2013.0503
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According to the characteristics of the electron beam high-voltage inverter power supply, high voltage transformer and voltage doubling rectifying circuit were combined for producing a 150 kV high voltage. Several common doubler rectifier circuit models were set up. The effect of capacitance parameters on the output voltage characteristic was simulated by using the MULTISIM software, especially the capacitance parameters of Cockcroft-Walton full wave voltage doubling rectifying circuit. Cockcroft-Walton full wave voltage doubling rectifying circuit was chosen. Experimental results show that the Cockcroft-Walton full wave voltage doubling rectifying circuit has a better performance and could get a better output voltage. The design scheme could meet the operating requirements.
Separator materials in microbial fuel cell contrary to waste treatment in space
Li Xingye, Jia Boyang, Xie Beizhen, Liu Hong
2014, 40(7): 1006-1010. doi: 10.13700/j.bh.1001-5965.2013.0494
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In order to obtain a separator material with higher performance and lower cost, four materials including alkaline battery separator, lithium-ion battery separator, and two different kinds of activated carbon-stainless steel separators were discussed. The results show that, the ordinary alkaline battery separator has excellent permeability of hydrogen, but the high permeability of moisture and oxygen restrains its application in microbial fuel cell (MFC) and needs to be further improved. The output power of MFCs with the rolled and brushed activated carbon-stainless steel separators is higher than that with cation exchange membrane, due to the lower resistance. The characteristics of the rolled and brushed activated carbon-stainless steel separators are similar, while the cost of the latter is lower, thus the brushed activated carbon-stainless steel separator is considered to be the ideal separator material for MFC.

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