2015 Vol. 41, No. 5

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Volume 41 Issue52015
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Oxidation behavior of 5A06 and 2A12 aluminum alloys in sulfuric-adipic acid and electrochemical property of anodic oxide film
LIU Jianhua, GAO Qingna, LI Yingdong, LI Songmei, YU Mei
2015, 41(5): 757-763. doi: 10.13700/j.bh.1001-5965.2014.0330
Abstract:
Anodic films of 5A06 and 2A12 aluminum alloys were obtained in sulfuric-adipic acid.The influence of alloy phase on anodic oxidation behavior, and the structure and corrosion resistance of the oxide film were analyzed. Electrochemical results were completed by the polarization curve and electrochemical impedance spectroscopy (EIS), and microstructure characterization of the anodic film was carried out by field emission-scanning electronmicroscopy (FE-SEM). 2A12 aluminum alloy showed two current peaks during anodization process, which shown that the dissolution of copper phase would influence the process of anodic oxidation. The pores of 2A12 anodic oxide film are not neat and have serious connectivity. Enrichment of copper phase promotes the production of oxygen. With the same soaked time, the corrosion potential of anodic oxide film on 5A06 is higher and corrosion current is lower than those of 2A12.The corrosion resistance of anodic oxide film on 5A06 is better. There properties all attributed to the higher porosity of Al-Cu alloy than that of Al-Mg alloy.
Integrated surveying method for FOG inclinometer aided by cable length
ZHANG Chunxi, LIN Tie, WANG Lu, LI Xianmu, XU Meibao
2015, 41(5): 764-769. doi: 10.13700/j.bh.1001-5965.2014.0382
Abstract:
In order to realize long-term surveying with high accuracy of fiber optic gyroscope (FOG) inclinometer, according to the logging operation, an integrated surveying method based on Kalman filter technology was proposed, which was aided by cable length information. The error model of inertial surveying system (ISS) and the measurement model of the cable length were introduced. The overall scheme of the integrated surveying method was designed. Meanwhile, the error state-space model of the integrated surveying system and the measurement update model were established. The proposed method was validated by semi-physical simulation. The simulation results show that, during 14 400 s simulation process, inclination angle error is less than 0.02°, toolface angle error is less than 0.12°, azimuth error is less than 0.98° and the position error is less than 47.5 m. Compared with the pure inertial measurement results, surveying errors can be reduced effectively, the long-term surveying precision is guaranteed and the performance of the instrument is improved.
Angular rate sensing based on mode splitting in an optical microresonator
YANG Zhaohua, HAN Xiaowei, YANG Xu
2015, 41(5): 770-775. doi: 10.13700/j.bh.1001-5965.2014.0329
Abstract:
Backscattering has been treated as one of the major error sources in resonant optic gyroscopes (ROG) in a traditional way, which has to be restrained. A microresonator with ultra-high quality factor can greatly enhance the backscattering light. As a result, it cannot be deemed as a disturbance noise anymore. Coupling of the scattering light and the original propagating light can induce mode splitting. The frequencies of the split modes change along with the angular rotation rate of the microresonator. Considering the Sagnac effect, the model that describes mode splitting in an active optical microresonator was modified and the explicit expression of angular rotation rate versus the splitting amount was derived. The resonator is preferred to work in the under-coupling regime by monitoring the reflection spectra at several excitation levels and taper fiber coupling conditions. Optical gain of the active medium can be utilized to manipulate the splitting profiles and to narrow the line widths, which helps the rate measurement. Theoretical analysis and simulation results show that the resolving power can reach 10-6 (°)/s in a microresonator with a quality factor of 108, providing a promising angular rate sensing mechanism.
Split-type implicit scheme using flux splitting and dual-time step for Euler equations
DONG Haitao, CHEN Zhe, LIU Fujun
2015, 41(5): 776-785. doi: 10.13700/j.bh.1001-5965.2014.0326
Abstract:
There are some shortcomings of the traditional implicit schemes such as complex forms and large amount of computations. Using the idea of operator splitting combining with implicit discrete schemes—flux vector splitting and dual-time step scheme—a simpler split-type implicit difference scheme for Euler equations was developed. The validity and reliability of the new implicit scheme were verified by performing numerical experiments on some typical problems in aerodynamics, and the properties of the new scheme were discussed in detail at the same time. The new scheme has common advantages of good stability and few constraints on time step just like other implicit schemes. In addition, the new scheme has the following advantages: it has simple formulas; it is easy for programming; it needs smaller amount of computations by avoiding solving systems of equations and doing inverse matrix operation compared with conventional implicit schemes in single time step; it has faster convergence rate compared with LU-SGS scheme.
Influence of engine inlet and exhaust on flying wing UAV and its mechanism analysis
YU Xinhua, TAO Yujin, ZHANG Lin, GAO Limin
2015, 41(5): 786-792. doi: 10.13700/j.bh.1001-5965.2014.0327
Abstract:
The inlet and exhaust can remarkably affect the pressure distribution and flow fields properties near the forebody and afterbody of the aircraft, therefore causing certain changes to the lift, drag and momentum characteristics. In order to know how inlet and exhaust affect aerodynamic characteristics of aircraft, computational fluid dynamics (CFD) numerical simulation technology was introduced to build a flying wing unmanned aerial vehicle (UAV) fairing model and an actual model, in which engine inlet and exhaust were taken into account. Boundary conditions of the actual model at the inlet and exhaust cross sections were set according to the different engine working conditions. Comparative analysis shows differences of flow fields and aerodynamic characteristics between these two models and reveals inner effect mechanism of the differences. The study on exhaust effect benefits the comprehensive aerodynamic design of aircraft/engine integrated system.
Electromagnetic interference caused by electric load of more electric aircraft
XIAO Chunyan, GAO Shuai
2015, 41(5): 793-801. doi: 10.13700/j.bh.1001-5965.2014.0339
Abstract:
As an increasing number of power electronic converters are used in the electrical system of more electric aircraft (MEA), electro-magnetic interference (EMI) problems are becoming more and more severe both within the electrical systems and between different systems. Based on the electrical load characteristics of MEA, electrical load was classified into rectification, chopping and inverter. The conduction EMI current of the three major electrical load during the stable operation and the load surge of electrical loads were studied by modeling and simulations. EMI characteristics caused by the inverter load obtained was verified by experiments. The research results show that the conducted EMI to the power line is concentrated in the switch frequency of the power electronic device and the multiple frequency or so; the step change of the high power electrical load after the Buck chopper circuit makes the conduction EMI characteristics change significantly, which reflected in the frequencies of local maximum of amplitude spectrum. The study results provide the guidance for the EMI identification and the filter design of an independent electrical system.
Discrete tolerance optimization for aircraft multi-joint assembly based on dynamic programming
TAN Changbai, KUANG Heng
2015, 41(5): 802-810. doi: 10.13700/j.bh.1001-5965.2014.0372
Abstract:
According to the nature of multi-stage decision of tolerance design for aircraft multi-joint assembly, a novel method of discrete tolerance optimization was proposed based on dynamic programming. First, coordination error models of typical three-joint assembly and four-joint assembly were presented. Second, a dynamic programming-based directed graph was built by introducing assembly quality indicator and cost indicator. Each individual graph node denoted an optional tolerance and contained optimal assembly quality index and cost index of rear sub-process. The constraint of tolerance selection between adjacent dimensional links was depicted by a directed edge linking two correspondent graph nodes. Finally, a two-phrase graph traversal algorithm was developed to make the optimal tolerance selection. The binary-indicator attribute of each graph node and edge were evaluated by inverse sequence method in the “backtracking” phase, and then a heuristic search algorithm was proposed to find the optimal route based on the binary-indicator attribute of each graph node in the following “forwarding” phase. This method was verified by a case study of helicopter tail beam and inclined beam assembly. The results show that the global optimal tolerance selection can be attained. Meanwhile, the efficiency of tolerance optimization is improved significantly by elimination of repetitive cost and assembly quality evaluations as well as diminishment of tolerance search space.
Fuzzy-clustering-based all-factor automatous validation approach of modal parameters of structures
ZHOU Sida, ZHOU Xiaochen, LIU Li, YANG Wu
2015, 41(5): 811-816. doi: 10.13700/j.bh.1001-5965.2014.0344
Abstract:
To solve the problem of modal parameter validation, an automatous validation approach of modal parameters was realize by using the fuzzy clustering analysis, which reduced the dependence of users' subjective experience on modal parameter validation, and improve the efficiency of modal parameter validation at modal analysis work. First, the modal parameters are divided into the scalar type and the vector type. Second, the scalar modal parameters were clustered by the convention fuzzy clustering approach. Third, the modal shape were fuzzy clustered by using a new proposed modal assurance criterion based metric function to solve the high-dimensional difficulty of fuzzy clustering. Then, combining the clustering results both of the scalar and the vector modal parameters, the all-factor automatous validation of modal parameters was accomplished. Finally, the proposed approach was validated by experimental results and illustrate that the proposed approach can automatously, accurately and high-efficiently validate the modal parameters.
Automatic code generation method based on Esterel
HE Yanxiang, YU Tao, LIU Jianbo, XU Chao
2015, 41(5): 817-824. doi: 10.13700/j.bh.1001-5965.2015.0108
Abstract:
Embedded systems development is much different from the traditional software development. Embedded system has the characteristics of small kernel, strong specificity, high reliability, high timeliness and complex target platforms, such that it requires higher designing criteria. Considering these problems existed in development process of embedded system, an automatic code generation method based on Esterel was proposed especially aiming at problems of complex development process, low-level automation of system, etc. The method employed the Esterel language to construct the target system that can be compiled to codes for multiple target platforms. Based on the design of operating system (OS) abstract layer, developers did not need to care about the implementation details for target platforms, which made it easier for the design of multiple target platforms, and achieved the automatic program design of embedded system. The experiments illustrate that the Esterel model can be compiled to codes correctly and efficiently for multiple target platforms, which implement the automatic code generation for target platforms.
United-proportional-navigation law for interception of high-speed maneuvering targets
LI Yuan, ZHAO Jiguang, YAN Liang, BAI Guoyu
2015, 41(5): 825-834. doi: 10.13700/j.bh.1001-5965.2014.0335
Abstract:
Aimed to high-speed maneuvering targets, three dimensional united proportional navigation (UPN) law was proposed. The guidance law combines the advantages of head-on and head-pursuit engagement through time-varying navigation ratio. The three-dimensional UPN law consisted of two planar laws can execute head-on with head-on, head-pursuit with head-pursuit and head-on with head-pursuit mixed models, which enlarge the capture region of interceptor tremendously. At planar engagement geometry, the analytic expression of line of sight (LOS) angular rate was deduced according to the target acceleration, and the time-variant navigation ratio was designed. While the planar UPN guidance law was extended into a three dimensional condition, the mistake of interceptor path angle and velocity at pitch plane in prior algorithm was modified and the target evading model was given. The simulation results show that, for high speed maneuvering targets, UPN has less miss distance than proportional navigation (PN) and retro proportional navigation (RPN), less control effort than augmented proportional navigation (APN) and larger capture region than the others.
Method for modeling and simulation of aircraft taxiing with unilateral and non-holonomic constraints
XU Ziyao, WANG Qi
2015, 41(5): 835-840. doi: 10.13700/j.bh.1001-5965.2014.0342
Abstract:
The motion of the aircraft taxiing along the ground was related to wind load and asymmetric braking torque. The method for modeling and simulation of the aircraft was presented on the basis of the dynamics of the non-smooth multibody system with non-holonomic constraints in order to analyze the dynamic behavior of the aircraft taxiing along the ground. The aircraft was treated as the multibody system which consisted of a rigid fuselage, two wheels of main landing gears and a wheel of nose landing gear. Two wheels of main landing gears rolled on the ground without slip. The lateral slip of the wheel on the nose landing gear was taken into account when the aircraft taxied along the ground. The dynamic equations of the system were obtained by Routh's equations and the constraint-stabilized method to reduce constraint drift. The frictional model between the wheels and the ground was the model of Coulomb friction which was described by the set value of function to determine whether the wheel of the nose landing gear slipped in lateral direction or not. Finally, numerical examples were presented to analyze the dynamic behavior of the aircraft undertook the wind load and the asymmetric braking torque.
Vibration model for multi-span beam with arbitrary complex boundary conditions
LIU Xiangyao, NIE Hong, WEI Xiaohui
2015, 41(5): 841-846. doi: 10.13700/j.bh.1001-5965.2014.0315
Abstract:
The transverse free vibration equations for Timoshenko beam were derived. Based on these equations, the vibration model for a multi-span beam with arbitrary complex boundary conditions was given by the transfer matrix method. Without considering the shear deformation and moment of inertia of the neutral axis, the model was simplified as the analogous model for Bernoulli-Euler beam. Three simplified models of some engineering significance were given. They are the free vibration model for a two-span beam, a cantilever with a lumped mass, and a beam with arbitrary lumped masses and translational springs. A comparison between the frequency equations derived by the three simplified models and those by the previous studies shows good consistency of the two, and it is thus concluded that the model developed in this paper is reasonable and feasible.
Uncertainty evaluation for the dynamic calibration of pressure transducer
LI Qiang, WANG Zhongyu, WANG Zhuoran
2015, 41(5): 847-856. doi: 10.13700/j.bh.1001-5965.2014.0356
Abstract:
The uncertainty of dynamic calibration for pressure transducer is a key indicator of its dynamic measurement precision. A novel grey method (GM) was proposed to evaluate the dynamic calibration uncertainty of pressure transducer. Firstly, a sine pressure generator was used to produce required sine pressure signal to drive the calibrated pressure transducer and obtain output of transducer. Secondly, using the grey relational analysis to deal with the measurement sequences outputted, a weighted value sequence was obtained. Thirdly, a grey model was established to calculate the calibration uncertainty of appointed frequency. Finally, a weighted least-square fitting method was applied to do fitting with the calibration uncertainty of appointed frequency, and then a dynamic calibration uncertainty model was established. An experimental verification under the calibration condition of changing amplitude and unchanging amplitude was set up. Grey method and Huang method (HM) were used to process the output of pressure transducer separately. The results show that the curve models of dynamic calibration uncertainty are consistent with each other in the setting condition. What is more, under changing amplitude, the relative error of calibration uncertainty obtained by the two methods is superior to 6% at appointed frequency points and is also less-than 10% at testing frequency points. Under unchanging amplitude, the relative error is less than 5% at most of frequency points and is superior to 0.018% at some testing frequency points. Based on the above analysis, it can be approved that the grey method can evaluate the dynamic calibration uncertainty of pressure transducer reliably.
Guidance law with angular constraints for head-pursuit or head-on engagement
YAN Liang, ZHAO Jiguang, LI Yuan
2015, 41(5): 857-863. doi: 10.13700/j.bh.1001-5965.2014.0369
Abstract:
For head-on or head-pursuit engagement, angle control proportional navigation (ACPN) and angle control retro-proportional navigation (ACRPN) closed-form trajectory shaping guidance law with impact angular constraints were proposed, which were based on proportional navigation (PN) or retro-proportional navigation (RPN) guidance law. ACPN with positive navigation ratio intercepted targets in head-on engagement, whose advantages were using less control efforts and final acceleration. ACRPN with negative navigation ratio intercepted targets in head-pursuit engagement. ACRPN's control efforts, miss distance and impact angle error were much less than that of guidance law in head-on engagement. Simulations demonstrate these claims mentioned above. Besides, the capture regions of ACPN and ACRPN for interception of high-speed targets are analyzed, which indicates that ACPN's capture region is larger than that of bias PN. Moreover, ACPN should be used to intercept targets in head-on engagement when the gimbal angle is less than sum of initial line-of-sight angle and 90°, and ACRPN should be used in head-pursuit engagement for the gimbal angle is equal to or greater than sum of initial line-of-sight angle and 90°.
Predictor-corrector reentry guidance satisfying no-fly zone constraints
ZHAO Jiang, ZHOU Rui, ZHANG Chao
2015, 41(5): 864-870. doi: 10.13700/j.bh.1001-5965.2014.0488
Abstract:
To enforce the lateral maneuverability of the reentry gliding flight, a predictor-corrector guidance method satisfying the no-fly zone constraints was proposed for the lifting hypersonic reentry vehicles. First, the longitudinal guidance was developed by the prediction of the landing error and the correction of the guidance command. The downrange was modified in real time by updating the magnitude of the bank angle. Then, a new handoff mechanism for the bank angle reversal logic was designed for the lateral guidance. The maneuver of the lateral motion was performed by employing the heading angle error corridor and the heading angle orienting area. Based on the CAV-H model, the numerical simulations show that the no-fly zone constraints can be satisfied by the predictor-corrector guidance method which is independent of the standard reentry trajectory. The Monte Carlo simulation results of the reentry gliding guidance with random initial dispersions and errors also demonstrate the robustness of the proposed algorithm.
Problems of network simplification by edge bundling
YAO Zhonghua, WU Lingda, SONG Hanchen
2015, 41(5): 871-878. doi: 10.13700/j.bh.1001-5965.2014.0501
Abstract:
Node occlusion and edge congestion problems, which are caused by the increment of network scale and complexity, had become a hot spot in network visualization research. To solve the visual clutter problem in network, edges close to each other in network were bundled by curving them. The bundling started from node position and group division, laying emphasis on edge bundling technique through edge convergence, edges bundled close to each other in network to reduce visual complexity. A segmental forced directed algorithm (FDA) simplification model and a group based consistent edge bundling network model were proposed and improved. In segmental FDA bundling model, quadratic spline was used to display line in network, control points of spline were produced by iteration to implement edge bundling. To solve the problem of excessive bending of some edges in segmental FDA bundling model, network was divided into different groups by CNM cluster algorithm. Lines in the same group were applied with edge consistent principle on basement of network group structure, and bundling level was calculated by the matching coefficient of edges. After edge bundling, the phenomena of curve's distortion decreased and curves became smoother. Domestic airline network data was chosen as experimental subject, and the network was simplified by two bundling models, and then the simplification result was analyzed. Experimental result shows that positions of nodes in the same group stand close to each other, and airline network shows distinct crossing skeleton. Airlines have north-south and west-east orientation bundle independently, which reveals the whole trends of airline network construction in these two directions. The bundling simplification algorithm introduced mentioned above has a wide applicability, and network visualized by this algorithm has good visual effect and readability.
Analysis of impact of use of composite materials on direct operating costs of airliners
YIN Hailian, YU Xiongqing
2015, 41(5): 879-884. doi: 10.13700/j.bh.1001-5965.2014.0320
Abstract:
The impact of the use of composite materials on the direct operating cost (DOC) of airliners needs to be evaluated at the preliminary stage of aircraft design. An analysis of the influence of the use of composite materials on aircraft cost and weight was carried out. A revised model for airliner weight and cost estimation was developed. An evaluation method was proposed to quantify the benefits of the use of composite materials in airliner design. A 150-seat airliner was used as a case for study. The impact of the percentage of the use of composite materials on DOC was evaluated for airliner design. The impacts of the fluctuation of aircraft price, fuel price and maintenance cost on DOC were investigated. The results show that the DOC of airliners declines with the increase of the percentage of the use of composite materials. With the increase of fuel prices, application of composite materials in aircraft design can bring remarkable economic benefits as the reduction of the costs of manufacturing and maintenance of the airframe of composite materials can lead to a significant decrease of the DOC of aircrafts of composite materials.
Depth control of robotic fish propelled by oscillating paired pectoral fins
MA Hongwei, BI Shusheng, CAI Yueri, NIU Chuanmeng
2015, 41(5): 885-890. doi: 10.13700/j.bh.1001-5965.2014.0331
Abstract:
The double-closed loop depth control method based on expert PID and fuzzy control was proposed, which was used to realize the depth control of robotic fish propelled by oscillating pectoral fins. The pitching moment acting on the robotic fish was produced by the oscillating angle control of the robotic fish's tail rudder. Then the pitch attitude of the robotic fish was changed, and it could achieve the up-and-down motion. Related depth control experiments of the robotic fish were also carried out. The reason that initial ranges of pitching angle under different target depth are different was analyzed. The experimental results show that the proposed depth control method can make the robotic fish reach the target depth accurately. After the robotic fish arrives in the target depth, the proposed method can also improve the pitching stability when the robotic fish swims in the target depth. The proposed control method can better realize the depth control of the robotic fish.
Changes of contamination deposition on spacecraft surface and evaluation of control factors
TANG Ping, ZHU Guangwu, QIN Guotai, LI Yongping, HE Yumei
2015, 41(5): 891-896. doi: 10.13700/j.bh.1001-5965.2014.0376
Abstract:
After spacecraft launched into space environment, molecule contamination and tiny particle contamination deposit on spacecraft surface and constitute the surface contamination layer. This contamination phenomenon has different levels of negative impacts on some technical systems. The on-orbit detection results of spacecraft surface contamination both in China and abroad were discussed. Surface contamination deposition changes and control factors were preliminarily evaluated. The result shows that deposition changes of surface contamination within the first 1 to 2 years after launch are controlled by the spacecraft outgassing mass by itself, outgassing rate, spacecraft surface temperature and air flow direction. The deposition mass within early period is larger, which is controlled by more surface outgassing by spacecraft itself within early period and higher deposition rate after launch. And the deposition mass is more in the ram area than in the yield area. The surface deposition in the later period shows obvious drop or slow fluctuations, and possesses omnidirectional characteristics. Some control factors with omnidirectional effect were discussed, among which high-energy particle flux and solar ultraviolet radiation flux may be the main control factors.
Robust design optimization of a two-dimensional airfoil with deformable trailing edge
ZHENG Yuning, QIU Zhiping, HUANG Ren, YUAN Kaihua
2015, 41(5): 897-903. doi: 10.13700/j.bh.1001-5965.2014.0387
Abstract:
In order to improve the aerodynamic stability of a two-dimensional airfoil with deformable trailing edge during the change of external conditions, a robust optimization method considering the uncertainty was proposed. Based on class-shape function transformation (CST) method, a parametric model was established to represent the geometry of a two-dimensional airfoil with a deformable trailing edge. The differences between robust optimization method and deterministic optimization method were discussed. Taking into account the uncertain airfoil geometry and inlet Mach number, the robust optimization method was applied to maximize the mean value of the lift-to-drag ratio and minimize its standard deviation. The actuation power requirement of the optimized airfoil with a deformable trailing edge was calculated. The results show that the robust optimization method can help to improve the aerodynamic performance of morphing airfoil and reduce the sensitivity of this performance to inlet Mach number simultaneously and to reduce the actuation power requirement of the robust optimal airfoil.
Predicting web search behavior based on gaze data
LU Wanxuan, JIA Yunde
2015, 41(5): 904-910. doi: 10.13700/j.bh.1001-5965.2014.0464
Abstract:
Predicting user's web search behavior is important for search engine improvements and user experience enhancements. Most existing studies are based on user's interaction data, including queries, clicks, cursor movements, etc. The prediction of web search behavior using gaze data was presented. To capture user's eye movement data during web search tasks, an eye-tracking study was conducted and the data were transformed into two data formats: histogram and sequence. The histogram data describes the distribution of user's attention while the sequence data presents user's scan path. Four learning methods were used to predict user decision or user intent and investigate the performances of the two data formats at the same time. The results show that the two data formats are both suitable for user decision prediction, and the sequence data is more suitable for user intent prediction. The results also demonstrate the effectiveness of web search behavior prediction using gaze data.
Cooperative jamming-detecting-attacking task allocation in air combat
RAN Huaming, ZHOU Rui, DONG Zhuoning, CHE Jun
2015, 41(5): 911-918. doi: 10.13700/j.bh.1001-5965.2014.0325
Abstract:
To solve task allocation problem of cooperative jamming in air combat, according to jamming power, jamming frequency bands and jamming style of our aircraft together with radar working power, working frequency bands, anti-jamming style of enemy aircraft, advantage of jamming power, jamming frequency, and jamming style were established. Considering the jamming capability of our aircraft and air combat capability of both sides, the total jamming advantage was established, and cooperative jamming task allocation model was built. According to the distance performance of enemy aircraft after jamming and air combat situation for both sides, detecting capability and attacking capability of our aircraft to enemy aircraft were studied, and cooperative detecting and attacking task allocation model was set up. Genetic algorithm was used to optimize and solve those cooperative task allocation problems. The simulation results demonstrate that those models can accomplish cooperative jamming task allocation, cooperative detecting and attacking task allocation.
Rapid anodizing technology replacing chromic acid for LY12CZ aluminum alloy
JI Zhenjiang, ZHU Liqun, LIU Huicong, LI Weiping
2015, 41(5): 919-924. doi: 10.13700/j.bh.1001-5965.2014.0352
Abstract:
Aluminum alloy anodizing coatings were prepared for LY12CZ in 45 g/L sulfuric acid solution through adding organic acid additive and buffering agent for fast film-forming, with the gradient voltage of 15-25 V, to replace the traditional chromic acid anodizing and boric-sulfuric acid anodizing. The field emission scanning electron microscope, titrating test, coating mass test and fatigue test were used to evaluate the properties of the anodizing coatings. The results show that organic acid additive and buffering agent for fast film-forming can relieve the dissolution of anodizing coatings, improve the compactness and corrosion resistance and reduce the fatigue damage during the anodizing process. Moreover, the properties of coatings anodized in the new anodizing solution of sulfuric acid, organic acid and buffering agent with the voltage of 15 V for 5 min and of 25 V for 5 min are equal to ones anodized in boric-sulfuric acid with the voltage of 15 V for 20 min. Organic acid additive is YP additive and buffering agent for fast film-forming is YJ additive.
Resistance evaluation for flying boats sliding at medium and high speed in calm water
SUN Jianjun, MA Dongli
2015, 41(5): 925-929. doi: 10.13700/j.bh.1001-5965.2014.0365
Abstract:
Considering the unique multimedia condition during take-off process of a flying boat and referring to the method of studying the resistance performance of a planning boat in the sliding process, a formula, to evaluate the resistance of a flying boat at medium and high speed in calm water, was proposed. The formula combines theoretical analysis and empirical correction and also includes the effect of aerodynamic distribution. With this formula, graphs illustrating hydrodynamic resistance and pitch angle varying with the volume Froude number were obtained and the reasons for the varying were analyzed. Take-off running distance was calculated with the hydrodynamic resistance and pitch angle that calculated from the formula. As the calculated take-off running distance is in consistent with experimental results, the validation of the formula was verified indirectly. And a method to calculate the take-off running distance of a flying boat was also proposed at the same time.
Multi-user identification based on double views coupling in cooperative interaction scenarios
YANG Yuhui, WANG Weijie, WAN Huagen
2015, 41(5): 930-940. doi: 10.13700/j.bh.1001-5965.2014.0454
Abstract:
An approach of multi-user identification based on double views coupling was proposed for the problem of identification error in cooperative multiplayer caused by occlusion and contact, in cooperative interaction scenarios. Double views motion tracking was established by the method of skeletons motion tracking and Kalman filter, with the depth cameras. Correlative finite-state machine was build using the motion tracking data of double views, to analyze the specific user motion status of coupling relationship and set up algorithms, the value of true or false tag was introduced to monitor and coupling correct multi-user identity in real-time. The new approach was compared with that of multi-user identity based on single view by experimentation, it is indicated that, the approach of multi-user identification based on double views coupling in cooperative interaction scenarios is more robust.
Optimization of drag-reduction by suction using multi-island genetic algorithm
ZHAO Dejian, WANG Yankui, ZHOU Ping, LI Qian
2015, 41(5): 941-946. doi: 10.13700/j.bh.1001-5965.2014.0345
Abstract:
To overcome the drawback of large suction mass requirement, the suction control for drag reduction was optimized. Computational fluid dynamics (CFD) in conjunction with multi-island genetic algorithm was employed as the tool to achieve the optimization. E387 airfoil was employed as the physical model. The suction location and mass flux of slot were set as the design optimization variables. The goal was to minimize both the airfoil drag and suction mass requirement by identifying the optimal suction location on the upper airfoil surface. The results show that the suction location and the suction mass requirement could be optimized by multi-island genetic algorithm. When the suction location is optimal, the mass flux of slot reaches the lower limit of the optimization interval with the airfoil drag reduced up to 8.3%. The occurrence of transition is not delayed by suction control so that friction drag is not reduced and the airfoil drag reduction is mainly due to the reduction in pressure drag.
Study on the ellipsoidal reflector interception methods for quasi-optical systems
LIU Dawei, WU Zhengxun, WU Zheng, LIU Kai
2015, 41(5): 947-952. doi: 10.13700/j.bh.1001-5965.2014.0322
Abstract:
For quasi-optical system, in order to improve the application performance of quasi-optical system on weather satellites, a new method of intercepting ellipsoidal reflectors that can effectively reduce extra energy loss in transmission and decrease the sizes of reflectors was proposed. Ellipsoidal reflectors are important optical elements for light beam transmission in quasi-optical system. The traditional method of intercepting ellipsoidal reflectors would introduce extra energy loss which deteriorates the performance of the whole system. To solve this problem, by building a Gaussian beam transmission model, traditional method of designing ellipsoidal reflectors was improved—translating ellipsoidal reflectors according to the beam waist radius. Simulations reveal that improved method performs better than traditional method—it not only reduces the maximal electrical level from-30 dB to-35 dB but also decreases the size of mirror by 10% to 30% which will benefit the electrical performance of quasi-optical system as a whole. All in all, improved method makes for decreasing the size and increasing signal-to-noise ratio (SNR) of the whole system, which ensures energy maintenance of weak meteorological signals during transmission process and improved method is of great significance to improve the properties of the quasi-optical system.
Retraction system performance analysis of landing gear with the influence of multiple factors
YIN Yin, NIE Hong, WEI Xiaohui, NI Huajin
2015, 41(5): 953-960. doi: 10.13700/j.bh.1001-5965.2014.0380
Abstract:
The landing gear retraction system is a mixed complex system consisted of mechanism, electricity and hydraulics. The retraction performance is affected by various factors. In most of the current studies, the subsystems are not well combined. Thus, a set of method combining theoretical analysis, multidisciplinary simulation and test verification was put forward, which provided a more accurate analysis method for the landing gear retraction system. Firstly, the dynamics equations of the retraction system were derived by power bond graph in detail. Then, a multidisciplinary simulation model was established, which combined the mechanism dynamics with the hydraulic system. This virtual prototype was verified by contrasting its results with the test results. At last, the key parameters' influence on the landing gear retraction performance was studied. The results show that, the pressure curves of the co-simulation model agree well with the ones of the test. Meanwhile, some key parameters, including crosswind, friction, damper orifices, liquid capacity and oil leak, affect the landing gear retraction performance in different degrees. Some meaningful results are concluded, which can be used as the guidances of the determination of retraction system parameters, the retraction fault analysis and the reliability study.