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2014 Vol. 40, No. 10

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Continuous control for probe landing based on Terminal sliding mode
Liu Keping, Zeng Jianpeng, Zhao Bo, Li Yuanchun
2014, 40(10): 1323-1328. doi: 10.13700/j.bh.1001-5965.2013.0638
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For the probe descending and landing safely, a continuous control method based on proportional plus derivative (PD) and nonsingular Terminal sliding mode was proposed. First, the dynamic equation was deduced in the landing site coordinate system. Then the nominal trajectory guidance method based on optimal polynomial in open-loop state was designed, by which the consumption of fuel was suboptimal. Third, the operability of PD control method was combined with the fast convergence and short adjustment time of nonsingular Terminal sliding mode control method. In the descending phase, the PD control method was adopted. In the landing phase, the continuous control method based on nonsingular Terminal sliding mode variable structure was adopted. The influence caused by uncertainty during landing was compensated by nonsingular Terminal sliding mode control, which could effectively suppress the influence of external disturbance and weaken the system chattering. Finally, simulation results demonstrate that the probe can land safely, and also show the effectiveness and robustness of the proposed method.
Pre-treatment of litsea cubeba nucleolus oil for bio-based aviation fuels
Zhu Yuelin, Liu Yajie, Ma Shengdong, Li Fan
2014, 40(10): 1329-1334. doi: 10.13700/j.bh.1001-5965.2013.0613
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Though litsea cubeba nucleolus oil has been used to prepare low level products such as alkanolamides for a long time, the main constituents including lauric acid, are thought to be excellent raw materials for bio-based aviation fuels since the carbon atomic numbers are around 8-16. Hydrogen peroxide decolorization, activated carbon/modified active floridin decolorization and phospholipase degumming methods were carried out to refine the oil and the best parameters were selected. It proves that the decolorization rate reaches up to 97.33% and the content of phosphatide is reduced from 1.036 mg/g to 0.036 mg/g. The results show that the best parameters are as follows,W(H2O2)=15%, t=80 min, T=110℃ for the H2O2 decolorization; the ratio of weight (activated carbon/modified active floridin)=1/15, t=40 min, T=80℃,W(adsorbent)=4% for the composite adsorption decolorization; and W(phosphatidase)=40 mg/kg, pH5.1, t=2.5 h, T=48℃ for the phospholipase degumming. It provides a cheap and convenient way with low loss rate and little effect on the component to refine litsea cubeba nucleolus oil to get bio-based aviation fuels by hydrodeoxygenation and other reactions.
Kinematical simulation analysis of steering system of mining dump truck based on adaptive differential evolution algorithm
Jiang Libiao, Cheng Cheng, He Jiashou, Liu Jianxiong
2014, 40(10): 1335-1340. doi: 10.13700/j.bh.1001-5965.2014.0104
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Spatial kinematics formulations were built on the basis of the steering system of 220 ton mining dump truck, which were verified by the model built in ADAMS and referring to the kingpin caster angle and kingpin inclination angle. This research focused to use MATLAB to program the dual-trial adaptive differential evolution algorithm (DADEA) in order to work out the global optimal steering property. It made inner and outer wheel's corner of 220 ton mining dump truck meet to the Ackerman steering geometry of considering the wheel cornering characteristics to achieve pure rolling when turning. The design variables are the arm length of the steering trapezium (K) and its base angle (Φ). The results of the optimal steering property were analyzed and compared to the optimal results generated by ADAMS. It turns out the optimization results obtained by MATLAB are better than those obtained by ADAMS. It was proven by real car tire comparison test that the former can make the steering design more reasonable, improve the serious type wore situations of mining dump trucks, and extend the service life of the type.
Design and validation of cold-flow test for air-breathing hypersonic vehicle
Deng Fan, Du Xin, Tan Huijun, Zeng Xianzheng
2014, 40(10): 1341-1348. doi: 10.13700/j.bh.1001-5965.2013.0617
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Cold-flow test is an important method for air-breathing vehicle to validate the inlet capability and aerodynamic characteristics. An airframe/propulsion integrative cruise vehicle with scramjet egine was designed; two-dimensional mixed-compression inlet and airframe/propulsion system coupling was used. The cold-flow wind tunnel test of the model was finished in hypersonic wind tunnel. Experimental data was measured when free Mach number was 5.0,6.0,7.0, and angle of attack was between -4° and 8°. The pressure performance test results indicate that, with the increase of the free stream Mach number, the total pressure recovery coefficient decreases, while the mass flow ratio increases firstly, and the maximum is obtained at design point; with the range of the angle of attack to a certainty, the total pressure recovery coefficient and the flow ratio increases. But after the cruise angle of attack, with the increase of the angle of attack, the total pressure recovery coefficient and the mass flow ratio decreases. The aerodynamics force performance wind tunnel test results validate the efficiency of the numerical simulation method, which shows a consistent trend with the experimental results, except the axial force coefficient. The aerodynamics characteristics of air-breathing hypersonic cruise vehicle could be obtained by revising the experimental results.
Analysis on characteristics of CO2 removal system of multi-cabin human spacecraft
Jin Jian, Hou Yongqing
2014, 40(10): 1349-1354. doi: 10.13700/j.bh.1001-5965.2013.0653
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Air environment of human spacecraft with multi-cabin is usually controlled by one core cabin through inter-cabin ventilation. An integrated simulation model of CO2 removal system of human spacecraft with multi-cabin was developed with Ecosimpro, including cabin sub module, crew sub module, CO2 removal sub module, and inter-cabin ventilation sub module. Using this simulation model, the characteristics of CO2 removal system were analyzed. According to the results, when crew number in cabins without CO2 removal equipment is up to 6 and air flux into CO2 removal equipment is maintained at 0.007 2 kg/s, CO2 partial pressure of cabins without CO2 removal equipment is beyond upper limit of 700 Pa. In that case, CO2 partial pressure could not be improved effectively by increasing inter-cabin ventilation flux. However, when air flux into CO2 removal equipment is increased from 0.007 2 kg/s to 0.011 3 kg/s, CO2 partial pressure of cabin without CO2 removal system is reduced below 700 Pa. The work is helpful to accelerate the process of design and improvement of air environment control system of human spacecraft.
Design of firmware upgrade algorithm for HINOC system
Cui Jingfei, Wang Jinlin, Zhang Zhen
2014, 40(10): 1355-1360. doi: 10.13700/j.bh.1001-5965.2013.0667
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High performance network over coax (HINOC) is a new technology of coaxial cable access, used for next generation broadcasting network. It can be used in triple play and the two-way cable TV network of digital and upgrade. The system is made up of HINOC bridge (HB) and HINOC modem (HM). In order to improve software function, it is necessary to update embedded software. File transmission and FLASH ROM program are basic processes in upgrades. In consideration of problems existed in widely used upgrades system such as low efficiency of encryption transmission and the lack protection for hardware failures, the system design introduced mechanisms such as coding and decoding of delta information, cryptography, file verification, and abnormal protection. According to the experimental results, the design meets requirements of HINOC in terms of efficiency, security and reliability. Information safety can be effectively protected, and the embedded devices can maintain basic function when abnormal problems happen.
Properties and fracture surface morphology of fiber-reinforced shell for investment casting
Lü Kai, Liu Xiangdong, Li Yanfen, Feng Hua, Wang Hao
2014, 40(10): 1361-1365. doi: 10.13700/j.bh.1001-5965.2014.0171
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In order to improve the properties of silicon sol shell for investment casting process, natural plant fibers combined with aluminum silicate fibers at natural-to-aluminum silicate fibers mass ratio of 1:1 were mixed into the slurries preparing for fiber-reinforced shell. The flexural strength of specimens of green shells, fired shells at different temperatures and the self-loaded deformation of the latter at elevated temperature were investigated. The fracture surface of shell specimens was observed by SEM. The results show that the green strength of shell specimens increases firstly and then decreases with variation of content of fiber from 0.2% to 1.0%. However, the self-loaded deformation at elevated temperature firstly decreases and then increases. The green strength of shell specimens reinforced with 0.6% fibers reaches the maximum of 2.94 MPa. The bending strength of shell specimens reinforced with 0.6% fibers fired at 900℃ reaches 4.04 MPa, approaching that of the non-reinforced shell specimens. It is found by SEM that the failure of the fiber-reinforced shell specimens at the applied load is resulted in breakdown of silicon sol films and pulling-out, fracturing and debonding of fibers in the shell.
Civil aircraft's exceedance event diagnosis method based on fuzzy associative classifier
Gao Xiaoxia, Huo Weigang, Feng Xingjie
2014, 40(10): 1366-1371. doi: 10.13700/j.bh.1001-5965.2013.0656
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Most of current civil aircraft's exceedance event intelligent diagnosis models are "black box" model, which donot contribute to analyze the occurrence of civil aircraft's exceedance event. In order to overcome these shortcomings, a civil aircraft's exceedance event diagnosis method based on fuzzy associative classifier (FAC) was proposed. First, quick access recorder's (QAR's) parameters value when exceedance event occured was extracted.Fuzzy C-means (FCM) cluster algorithm was adopted to preprocess extracted QAR's parameters value. Then, the library of fuzzy associative classification rule (FACR) was generated by Apriori algorithm.Genetic algorithm was used to prune the library of FACR.Finally,fuzzy classification reasoning method was integrated to build FAC. The FAC was verified with sample data generated by B737-800. Experiment results show that the FAC can diagnose exceedance event effectively, and its classification error rate is equivalent to least squares support vector machine (LS-SVM), but its interpretability is superior to LS-SVM.
Selection of shifting element design based on genetic algorithm
Ma Mingyue, Liu Yanfang, Xu Xiangyang, Wang Yi
2014, 40(10): 1372-1377. doi: 10.13700/j.bh.1001-5965.2013.0619
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Based on the kinematic analysis of planetary gear mechanism and shifting element, an intelligent algorithm applied for selection of the shifting element design of automatic transmission was presented. Unlike traditional design methods, the characteristic parameters of the planetary gear mechanism were optimized based on genetic algorithm. According to the condition of the shifting logical, the offset value of the design was defined, and the fitness function of the shifting element design optimal algorithm was constructed. This method took the ratio sequence and shifting logical into account at the same time to shorten the design cycle. Based on MATLAB, selection of the shifting element design of ZF-8AT was realized and 3 optimal shifting element designs were obtained. The results demonstrate that the selection algorithm proposed is effectively able to realize shifting element design.
Fault tolerant control of multi-effectors aircraft using integral sliding model with WPI
Wang Fawei, Dong Xinmin, Wang Xiaoping, Xue Jianping
2014, 40(10): 1378-1385. doi: 10.13700/j.bh.1001-5965.2013.0623
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An integral sliding model using dynamic adjustment weighted pseudo inverse (WPI) was proposed to fault tolerant control for over-actuated aircraft actuator damaged, which had fault reconstruction error and time delay, position and rate limiting. The instruction restricts module was used to limit saturation control command and instantaneous disturbance. A control allocation scheme using dynamic adjustment WPI was designed to gradually reduce instruction saturation. The control allocation was reconstructed by failure estimate to compensate the aerodynamic loss, which reduced the effects of fault for system stability. An integral siding model control law was designed to ensure system stability with fault reconstruction error and time delay. The simulation results show good track performance, as well as the robust for time delay and tolerant ability for actuator damaged.
Calculation and simulation of stratospheric airship capsule stress considering the pressure gradient
Liu Longbin, Lü Mingyun, Xiao Houdi, Cao Shuai
2014, 40(10): 1386-1391. doi: 10.13700/j.bh.1001-5965.2013.0629
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The capsule volume of stratospheric airships was usually too huge and the surface curvature of buoyancy capsule was small, so local stress concentration of airship envelope could easily lead to large transformation and cause the capsule to overpressure damage and blast quickly. Basing on the pressure gradient loading condition of the inside and outside of the airship buoyancy capsule, the theoretical calculation method of the hoop and axial stress was developed under the real overpressure load working situation, and the Von Mises stress strength criterion was proposed as well. The finite element (FEM) analysis software ABAQUS was used to simulate the hoop Von Mises stress under the different overpressure loads of 300, 500 and 800 Pa respectively. The contrastive results show the Von Mises values between the simulation and theoretical calculation are in consistent nearly, and the hoop Von Mises stress of airship capsule envelope increases with the increasing of pressure gradient, While the axial Von Mises stress of airship overpressure capsule is determined by the hoop Von Mises stress and envelope local curvature of the warp and weft directions together, moreover, the two kinds of Von Mises stress associated with the overpressure load is positively correlated at different directions, which provides the effective basis research of stress evaluation and strength calculation for the airship envelope overpressure.
Fast algorithm of motion state detection based on tri geo-satellites
Yang Yuxiang, Zhang Huichuan
2014, 40(10): 1392-1398. doi: 10.13700/j.bh.1001-5965.2013.0631
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Aiming at the difficulty to detect the motion state of targets in the satellite-borne passive location system, a fast motion state detection algorithm, based on the principle that the location result of the dual-satellites geolocation using differential time offset (DTO) and differential frequency offset (DFO) should be consistent with that of the tri-satellites geolocation using dual DTOs under the stationary hypothesis, was proposed. Firstly the region of target was obtained by location error analysis. Then the DFO range of this region under the stationary hypothesis was obtained through the statistics. Finally the observed value of DFO at the location time was compared with the DFO range to detect the motion state of target. And the expression of theoretical detection probability was given. The algorithm was verified by the simulation and experiment results. For the targets with velocity above 40 m/s, the detection probabilities are more than 99% when the estimation precision of DTO/DFO is 10 μs/100 mHz. It is demonstrated by the practical data that the proposed algorithm helps the system improve the ability to detect motion state significantly.
Packet time delay of polling-based multiplexing in advanced orbiting systems
Zhang Meng, Xiong Huagang, Zhao Hongbo, Xia Ying
2014, 40(10): 1399-1404. doi: 10.13700/j.bh.1001-5965.2013.0661
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Most researches on multiplexing in advanced orbiting systems (AOS) were made by simulation, and few literatures got theoretical results. The packet time delay of polling-based multiplexing in AOS was studied. Mathematical model was established by using vacation queue system with non-exhaustive service, and it was analyzed through cycle regeneration method. A calculation formula of multiplexing packet time delay was derived, and the lower bound value was also obtained. Simulation results show that when the packet arrival rates are 1, 2, 3 packets per second and downlink rate ranges from 240 to 330 bit/s, simulation values of packet time delay are larger than the theoretical lower bound values, which proves the correctness of theoretical derivation. The results can provide reference for practical engineering design.
H∞ controller design for a class of nonideal switched systems
Li Wei, Wang Qing, Dong Chaoyang
2014, 40(10): 1405-1410. doi: 10.13700/j.bh.1001-5965.2013.0665
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A class of smoothly switched system model was proposed to describe the phenomena of dynamics switching that generally occured in real-world processes, and the problem of robust H∞ switching controller design was investigated for systems of this kind. Based on the average dwell time method and the differential inequality theory, the sufficient condition was presented such that asymptotic stability and some given L2 gain are guaranteed for the smoothly switched system. The design criterion of the robust H∞ switching controller was further obtained in terms of linear matrix inequalities. The smoothly switched system model covers the prevailing switched system model as a special case; therefore the controller synthesis method in this note is applicable to traditional switched systems. A design example on a morphing aircraft illustrates that the resultant tracking control system qualifies well robustness against parameter uncertainties while possessing stability and acceptable tracking performance.
Fractional integral sliding mode nonlinear controller of electrical-hydraulic flight simulator
Han Songshan, Jiao Zongxia, Wang Chengwen, Shang Yaoxing, Shi Yan
2014, 40(10): 1411-1416. doi: 10.13700/j.bh.1001-5965.2013.0689
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Electrical-hydraulic flight motion simulator is the key equipment in hardware-in-the-loop testing of flight control systems. It can accurately reproduce, in real-time, the flight motion of aerial vehicles under laboratory conditions, which has great economic value and plays a very important role in the national defense. Based on fractional integral sliding mode surface, a nonlinear robust controller was proposed to improve its dynamic tracking accuracy. This nonlinear robust control approach introduces fractional order calculus in integral sliding mode controller, which can further improve transient performance and offer more degrees of freedom. In presence of strong disturbance torque, parametric uncertainty and nonlinear friction, the globally asymptotic stability of developed nonlinear robust controller was proved via Lyapunov analysis method. Under various working conditions, comparative simulation results of outer-axis's motor in a type of flight simulator demonstrate the effectiveness of the proposed nonlinear robust algorithm, which can guarantee transient performance and effectively improve the robustness.
Effects of modification on jet mixing of sword alternating lobed nozzle
Sheng Zhiqiang, Huang Peilin, Ji Jinzu, Wang Ying
2014, 40(10): 1417-1423. doi: 10.13700/j.bh.1001-5965.2013.0633
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A novel lobed nozzle named as sword alternating lobed nozzle was designed, combined with the characteristics of the existing alternating lobed nozzles to modify the baseline lobed nozzle. The effects of scalloping and scarfing on jet mixing of sword alternating lobed nozzle were investigated by numerical method. The results show that when the degree of scalloping or scarfing enhanced, the mixing in the downstream region of the lobe peak is accelerated, however the center primary flow needs a longish journey to be mixed. Scarfing has more capacity on promoting mixing than scalloping. Pumping performance and flow loss change little with scalloping whereas decrease slightly with scarfing. The results also indicate that the form of streamwise vortices has higher influence on mixing efficiency compared with the intensity of streamwise vortices.
Weapon-target assignment based on Memetic optimization algorithm in beyond-visual-rang cooperative air combat
Yan Ji, Li Xiangmin, Liu Lijia, Zhang Fengxia
2014, 40(10): 1424-1429. doi: 10.13700/j.bh.1001-5965.2013.0643
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In beyond-visual-rang (BVR) cooperative air-to-air combat, weapon resources could be wasted if all weapon units are fully assigned at a time. To cope with the disadvantage, a new weapon-target assignment mathematical model based on the threshold of damage probability was proposed. The new model guarantees the threshold of damage probability by employing fewer weapon units to save and make full use of weapon resources. The proper fire units were assigned to the targets according to the priority of menace. Meanwhile, the maximum of the target damage probability average value can also be achieved. Based on the new model, a Memetic algorithm, using the discrete particle swarm optimization (DPSO) algorithm as the global search strategy and greedy algorithm as the local search strategy, was proposed to solve the weapon-target assignment problem. Simulation results show the advantage of the proposed new model and the effectiveness of Memetic algorithm.
Parameter determination of Chaboche kinematic hardening models and ratcheting simulation
Jiang Jinpeng, Chen Tao, Jin Ping, Wang Jue
2014, 40(10): 1430-1435. doi: 10.13700/j.bh.1001-5965.2013.0655
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Chaboche kinematic hardening model is a powerful tool to evaluate the cyclic behavior and it can predict the ratcheting phenomenon. Parameters in three Chaboche kinematic hardening models were determined using genetic algorithm considering both hysteresis loop and ratcheting. In the three models, model with four nonlinear components has the best prediction for ratcheting compared with experimental results. Peak strain increases when increasing stress amplitude or mean stress, and strain accumulation rate accelerates at the same time. Ratcheting was simulated using Chaboche kinematic hardening model containing four components to study the effects of loading sequence on ratcheting. Results show that loading sequence of mean stress makes a difference on ratcheting. Accumulated strain under high-low loading sequence is lower than that under low-high loading sequence. The higher the former mean stress is, the lower the accumulated strain under the later load is. However, loading sequence of stress amplitude has little impact on accumulated strain.
Fault detection and identification for a dual-redundant brushless DC motor system using wavelet transform and hierarchical clustering algorithm
Wang Xin, Du Yang, Zhou Yuanjun, Ma Qishuang
2014, 40(10): 1436-1441. doi: 10.13700/j.bh.1001-5965.2014.0207
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In order to implement the high reliability and wide-ranged speed control of an electro-mechanical actuator (EMA), a novel scheme was proposed to detect and identify faults of a dual-redundant brushless DC motor (BLDCM) system, which combines wavelet transform (WT) technique with hierarchical clustering algorithm (HCA) by testing the existing bus-current signals in each channel and using the features of the specific system structure and commutation process. Experimental results reveal that the motor open-phase faults and all kinds of inverter-transistor open-circuit faults of this BLDCM system can be correctly detected and identified with high robustness for the impact of wide-ranged motor speed, operating load, and even unexpected noise. This method is so sensitive to the sudden changes of the bus currents that it is very powerful for detecting those faults which lead to abnormal commutations. It needs no more extra devices, and is of low complexity, well fault-distinguish ability, high reliability and practical simplicity.
Numerical simulation of two dimensional ice accretion based on lubrication theory
Hou Shuo, Cao Yihua
2014, 40(10): 1442-1450. doi: 10.13700/j.bh.1001-5965.2013.0625
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Water film-ice layer model based on lubrication theory was extended to two-dimensional orthogonal curvilinear coordinate system on arbitrary sections. Two governing partial differential equations of water film flow and ice accretion on curved sections were obtained. The numerical methods for solving these unsteady governing equations were presented. An implicit-explicit discrete scheme was applied to obtain the algebraic form of governing equations. Examples of numerical icing calculation were verified on NACA0012 airfoil and circle cylinder section in typical aero icing and structural icing environment. The results of calculation using current model were compared with ice shapes of simulation using traditional Messinger model and results from ice wind tunnel tests. Ice shapes on airfoil obtained using this numerical method were close to icing curves calculated by Messinger model in low temperature glaze icing conditions. In relatively high temperature icing conditions, more accurate results were obtained than Messinger model compared with results of ice tunnel experiments. Ice accretion on transmission line wires which cannot be predicted properly by traditional Messinger model was also effectively predicted by current model in structural icing conditions.
Packet scheduling algorithm for multi-service MIMO-OFDMA downlink systems
Liu Zhuang, Li Xi, Ji Hong
2014, 40(10): 1451-1456. doi: 10.13700/j.bh.1001-5965.2013.0616
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A utility-based packet scheduling algorithm was proposed for downlink multiuser multiple input multiple output-orthogonal frequency division multiplexing access (MIMO-OFDMA) systems. The proposed algorithm not only considered the channel condition of physical layer, but also utilized the transmitting buffer status information and the automatic repeat-request (ARQ) feedback information to help improve the system performance. In order to satisfy the different qualities of service (QoS) of multi-service, different utility functions were designed for different traffics and then the scheduling problem was formulated into a problem of overall system utility maximization. Moreover, considered the limits of practical long term evolution (LTE), a heuristic algorithm with low computational complexity was proposed. The simulation results show that the proposed algorithm outperforms the existing algorithms in terms of the system throughput and the packet loss rate and can also guarantee the QoS demand of real-time traffic.
Cooperative guidance of multi aircraft in beyond-visual-range air combat
Ran Huaming, Zhou Rui, Wu Jiang, Dong Zhuoning
2014, 40(10): 1457-1462. doi: 10.13700/j.bh.1001-5965.2013.0620
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To solve the task allocation problem of air-to-air missile guidance power handover, according to the situation of our aircrafts to missiles whose guidance power needs to be turned over, situational advantage model to the missiles was established. Detecting capability model to missiles' targets was established by the situation of our aircrafts to the targets. Threat degree model of enemy aircrafts to our aircrafts was established by the situation of enemy aircrafts to our aircrafts. Air combat effectiveness advantage model was established by the air combat capability of both sides. On the basis of these four models, the whole guidance superiority model of our aircrafts to missiles was established. Cooperative guidance task allocation model was established based on the whole guidance superiority, genetic algorithm was used to optimize and solve the cooperative guidance task allocation problem. The simulation results demonstrate that this method can calculate guidance superiority and do task allocation in real time, and can accomplish multiple cooperative guidance feasibility.
Adaptive cubic convolution based image interpolation approach
Li Chunlong, Pan Haixia, Wang Huafeng
2014, 40(10): 1463-1468. doi: 10.13700/j.bh.1001-5965.2013.0621
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Image interpolation is an important technique of image processing, which can be used in many image process areas. In recent years, it is often used to zoom in or zoom out images. A novel effective image interpolation mechanism to enhance the enlarged image edges was proposed for the visual artifacts problem in traditional magnification algorithms and the high computational cost in some adaptive image interpolation algorithms. The proposed algorithm combines the edge-directed gradient with the cubic convolution interpolation algorithm to obtain the higher quality of an image both in the edges and smooth areas. The result shows that the proposed algorithm gets a better visual effect and effectively removes the jaggy and blur at the edge. The proposed algorithm is less complex with running time reduced by 3.19 s on average, compared with the edge-adaptive interpolation algorithm, and has higher quality with the peak signal-to-noise ratio (PSNR) raised by 0.89 dB on average, compared with the cubic algorithm.
Application of the improved fuzzy comprehensive evaluation method in forming processing decision-making for the composite component
He Long, Mei Zhongyi
2014, 40(10): 1469-1476. doi: 10.13700/j.bh.1001-5965.2013.0663
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The original fuzzy comprehensive evaluation method can be improved and converted to the computer-operable decision-making algorithm which can solve the problem of making the forming processing decision for the aircraft composite component, and the evaluation result is more consistent with actual production. The membership degree calculation method was introduced to determine the evaluation matrix and it achieved the computer instead of manpower to complete determining the evaluation matrix. The increasing safety margin method for the scope of the evaluation was adopted to avoid the problem that dividing the evaluation scope boundaries is too absolute by the original fuzzy comprehensive evaluation method. The dynamic weight distribution method was combined with the ratio method to achieve the computer automatic weight distribution, and it ensured the effective allocation results to meet the user's actual preferences. By using the improved fuzzy comprehensive evaluation method as the core algorithm, the computer aided forming processing design system for the composite component was developed. The developed system was applied in the actual forming processing decision-making, and the decision result was conformed to the actual production. It indicates the feasibility and accuracy of the method in the application of the computer-aided forming processing decision-making.
Spatial straightness error evaluation based on three-dimensional least squares method
Wang Bingjie, Zhao Junpeng, Wang Chunjie
2014, 40(10): 1477-1480. doi: 10.13700/j.bh.1001-5965.2013.0644
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Spatial straightness error is very important for the assessment of mechanical product precision. The spatial straightness error evaluation algorithm with high precision is needed in real project. In order to evaluate the spatial straightness error more accurately, a mathematical model of spatial straight line fitting was established based on the national standard (GB/T 11336—2004) and three-dimensional least squares method, the exact solution to the model was deduced. The diameter of the minimum cylindrical surface of the least squares was obtained by using the method of spatial projection, coordinate transformation and lattice method. The proposed method was validated by numerical experiments. It is not only more accurate and robust, but also easy to be implemented.

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