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2012 Vol. 38, No. 5

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Energy management ascent guidance algorithm with multiple constraints
Xu Heng, Chen Wanchun
2012, 38(5): 569-573.
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The ascent guidance for hypersonic vehicle launch mission needs to satisfy multiple constraints. For the solid-powered launch vehicle without burn control, energy management was applied to satisfy the constraints. To achieve the energy management, the basic idea is to control the angle between the thrust and the velocity. Based on the alternate attitude control energy management (AEM) and the general energy management (GEM), the spline energy management (SEM) guidance was proposed, and modified for the constraint that the attitude angle should be constant before separation. A three-stage launch vehicle example was demonstrated. Comparing the AEM, GEM and SEM simulation results, the feasibility of the SEM guidance is verified.
Optimal correction strategy during Lambert transfer from view of probability
Xu Ming, Tan Tian, Li Zhiwu
2012, 38(5): 574-578.
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Monte-Carlo simulation and genetic algorithm were employed to achieve the optimal correction strategy during Lambert transfer from the view of probability. The Lambert trajectory associated J2 perturbation was generated from differential correction algorithm that was used to yield the periodic orbit in circular restricted three body problem (CR3BP). So the correction maneuvers dealt with just the residual errors from navigation and controller. Then the linear and nonlinear strategies were derived from the monodromy matrix of differential correction algorithm, and then the Monte-Carlo simulation and genetic algorithm were employed to minimize the rendezvous errors from the view of probability. Quite different from the traditional strategies, the correction developed is universal for its robustness to measure errors.
Rapid aircraft structure modeling based on structure case base
Feng Haocheng, Luo Mingqiang, Liu Hu, Wu Zhe
2012, 38(5): 579-584,590.
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In order to utilize and study more effectively from existing examples of aircraft structure information, the parametric object-oriented description method of structure instance was studied. The architecture framework of aircraft structure case base was proposed and the prototype system was established. The design method of aircraft structure based on structure case base was studied. The parametric modeling method of fuselage structure and wing structure was represented. The functionality of rapid aircraft structure design based on structure case base was achieved in an open conceptual aircraft design system.An instance is given to illustrate the effectiveness of the system and methods.
Trajectory tracking for automated aerial refueling based on adaptive dynamic inversion
Gai Wendong, Wang Honglun, Li Dawei
2012, 38(5): 585-590.
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Receiver aircraft trajectory tracking control is studied during the automated aerial refueling (AAR). The method of the outer guidance loop and inner control loop was adopted. The method was proposed to combine the nonlinear path-following guidance and adaptive neural networks, and was used in receiver aircraft trajectory tracking. The improved nonlinear guidance law was used to guide the receiver aircraft in longitude and latitude. The disturbance and model error were compensated in the angular rates loop. The angular rate error equations with proportional-integral desired dynamics were used to design the update law for the adaptive neural networks. Results show, during the receiver aircraft approaching to the tanker, by using this method, the receiver aircraft ability of restraining disturbance and accommodating model error can be improved effectively, and the control requirement in automated aerial refueling can be met.
Light-stripes fast matching method for raster binocular stereo vision sensor
Wei Zhenzhong, Fan Yanrui, Hou Yarong
2012, 38(5): 591-594,600.
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Raster binocular stereo vision sensor is widely used in 3D measurement, and one of its difficulties is light-stripe matching and recognizing. Based on the relationship between the viewed stripes number and the stripe sequence combination, a fast matching method for light-stripe based on 3D searching was proposed. The raster binocular stereo vision system was regarded as two raster structured light sensors, and then was calibrated under one common coordinated system. So, the 3D coordinates of the light stripes center points were obtained by the two raster structured light sensors, respectively, as well as the distances between the light-stripe center points. As a result, the light-stripes whose model numbers are equal and have the minimal distance are matching stripes. All the possible combinations were listed after the relationship between the viewed stripes number and the stripe sequence combination, and the matching method was designed with the character of much less extra calculations which brings about less computational burden. The experiment results show the effectiveness of the method.
Influent of inerting process of multi-bays central fuel tank for civil passenger airplane under various gas distributions
Feng Shiyu, Feng Chenxi, Wang Qixiang, Liu Weihua
2012, 38(5): 595-600.
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Based on the assumption of zero mass accumulation in the fuel tank and all bays, a mathematical model to automatically determine the flow direction and rate via the pressure difference was set up, and iterative steps were offered. Then, the mole concentration of the oxygen in the each bay related to volumetric tank exchange of ullage via the differential method was obtained. Adopting Boeing 747 central wing tank as the object of study, the calculating results of the models show highly accurate with the experimental data published on the foreign literature. The central fuel tank of an unnamed domestic passenger airplane was employed to study the inerting process influenced by 4 different configurations of the nitrogen-enriched air inlet port and 2 different gas distributions. The result reveals that the inering effect is the best to distribute the nitrogen-enriched air into all bays according to the volume average while it is the worst to solo distribute the nitrogen-enriched air into an outside bay. Moreover, it is better to emplace the inlet ports on the symmetrical bays than the asymmetrical bays.
Preparation and atomic oxygen resistance of polyimide/inorganic oxide composite films
Wang Kai, Xiao Fei, Zhan Maosheng
2012, 38(5): 601-604.
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Three series of polyimide/inorganic oxide composite films were synthesized through sol-gel method using zirconium n-butoxide, tetrabutyl titanate and tetraethyl orthosilicate as the oxide precursor, respectively. The atomic oxygen (AO) resistance testes of the films were carried out using a ground-based atomic oxygen effects simulation facility. The atomic oxygen fluence is about 3.1 1020 atom/cm2. The results indicate that the dispersing status of inorganic oxides will affect on the mechanical properties of polyimide films dramatically, and the inorganic oxides-rich layer is formed on the polyimide film after AO exposure, which decreases the mass loss rate and improves the AO resistance of polyimide films obviously.
Optimization in the stable region of demand information sharing supply chain systems
Wang Jing, Yang Huan, Han Weiwei
2012, 38(5): 605-613.
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A DIS-APIOBPCS (demand information sharing-automatic pipeline inventory and order based production control system) model was established to confirm the system-s stability indexes. Based on the impact of system parameter on the system stability, the system stable region was confirmed. Three stability indexes were established which were ITAE (integral of time absolute error), ORATE (order rate) maximum deviation and Wn (noise bandwidth). According to optimization theory, a group of optimal solution was searched out through multi-object algorithm NASA-Ⅱ in the stable region of the system which makes the stability indexes Pareto optimal which means that one individual index could not make better off without making any other individual index worse off. The optimal stability indexes and the corresponding system parameters can be obtained in different parameters of lead time in the stable condition. Valuable insights into the importance of the stable operation of the system and the influence of the system parameters on the system-s performances in the system stable region were obtained, and then relative managerial strategies were proposed.
Hydraulic system simulation platform under the framework of airborne electromechanical integrated management
Deng Shuo, Yang Bo, Wang Yunlu, Wang Jiangyun
2012, 38(5): 614-619.
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The simulation platform of aircraft hydraulic system had been designed based on the utility management system. Its design concept and structure of simulation platform were described, the principle and realization of each subsystem of simulation platform were expounded, and the design concepts and control algorithm of the flow rate pressure simulation hydraulic load module were analyzed. The hydraulic oil temperature of different flight stage was simulated by adopting the average temperature calculation method. Simulation test results and the design scheme of aircraft hydraulic utility management system were presented. Test results show that hydraulic system simulation platform can effectively achieve the actual hydraulic system features and has provided favorable support for implementation and optimization of aircraft hydraulic system in the electromechanical integrated management.
Optical flow/INS multi-sensor information fusion
Liu Xiaoming, Chen Wanchun, Xing Xiaolan, Yin Xingliang
2012, 38(5): 620-624.
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Several optical flow sensors were mounted dispersedly on a missile airframe. The airframe kinematics model in the vertical plane and the optical flow sensor measurement model were established. Discrete-time Kalman filters were used to fuse the optical flow data and rate gyroscope data, and estimate the altitude, attitude and velocity of the airframe. A very-low altitude-holding flight simulation was then implemented based on these estimations. The simulation results indicate that several optical flow sensors and a rate gyroscope can be used to estimate the altitude, vertical velocity, pitching angle, pitching angular velocity and attack angle exactly and real-time. These estimations can help to implement very-low penetration missions.
AQSSE method for damage identification of base-isolated structures
Mu Tengfei, Zhou Li, Yin Qiang
2012, 38(5): 625-629.
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A new data analysis method, referred to as the adaptive quadratic sum-squares error(AQSSE) method,has been investigated for the online identification of time-varying system parameters of structures. Experimental study was conducted and presented to verify the capability of the AQSSE approach for identifying and tracking the variations of structural parameters. A base-isolated building model was tested in the laboratory. A stiffness element device was proposed to simulate the abrupt reduction of model stiffness due to damage during the tests. Both El Centro and Kobe earthquake excitations were used to drive the test model. Different damage scenarios were simulated and tested. Then the AQSSE approach was used to track the variation of the stiffness during the test based on the measured acceleration response data. The tracking results for the stiffness variations correlate well with that of the referenced values obtained by finite element method. It is concluded that the AQSSE approach is effective and accurate in tracking the variations of structural parameters leading to the detection of structural damages, including the time, location and severity of the damage.
Structural optimization design based on non-probabilistic convex modeling reliability
Wang Xiaojun, Wang Lei, Jia Xiao, Qiu Zhiping
2012, 38(5): 630-635.
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Taking into account the uncertainty of structural system parameters and based on the proposed new definition of the non-probabilistic reliability index based on convex models, a new mathematical model and solution method of structural optimization design was proposed under the non-probabilistic reliability constraint. The super-ellipsoidal convex sets were taken to describe the uncertain parameters. The ratio between the volume of safe region and the total volume of the super-ellipsoidal set for the basic uncertain variables was defined as the measurement of structural non-probabilistic reliability. By taking the reliability index as constraint condition, the structural optimization problem was iteratively solved through the multiplier method and the damping Newton-s method, which was a stable, efficient algorithm. Numerical examples verify the correctness of the proposed method.
Object auto-segmentation based on watershed and graph cut
Liu Rong, Peng Yanmin, Tang Can, Cheng Sheng
2012, 38(5): 636-640,647.
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In order to segment CT slices mostly and accurately, watershed algorithm and graph cut were combined. Firstly, the inner contour and the outer contour of the target object were selected, and then watershed algorithm was applied to divide the region between contours into series of smaller regions. Each smaller region was regarded as a node to establish the graph. Multiple sources and multiple sinks can be converted to the single source and the single sink to refine the graph. Secondly, the target object of the first CT can be extracted by the maximal-flow cut. Thirdly, mapping the contour to the next CT, the contour was reduced and expanded to regard as the inner contours and the outer contours. Then the next CT was segmented. Followed by the cycling, the entire sequence of CT will be operated. The experiment proves that this algorithm is more effective in the segmentation and the running time than the other traditional algorithms. Meanwhile, the contours of the series of CT were extracted automatically.
Three dimensional numerical simulation of rotor in vertical descent flight
Cao Dong, Cao Yihua
2012, 38(5): 641-647.
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Using the actuator disc model, blade element momentum theory and computational fluid dynamics(CFD)method, the flow field and aerodynamic performance of a helicopter rotor in vertical descent flight were simulated. In calculation, the loads of spinning rotor were represented as momentum source terms distributed along the span of the rotor with functional relationship to the local flow conditions. The finite volume method was adopted and incompressible Navier-Stokes (N-S) equation was solved in Cartesian coordinates. The Spalart-Allmaras(S-A) turbulence model, especially the induced velocity empirical formulae were also included in the calculation method. The simulation results for flow field and aerodynamic performance show good agreement with the experiment data. Therefore, this numerical simulation technique is proved to be feasible for analyzing rotor flow characters in descent condition and it also provides the references for the further vortex ring state research.
Network coding-aware opportunistic forwarding mechanism in wireless multi-hop networks
Yuan Yongqiong, Zhang Jun, Wang Yun
2012, 38(5): 648-653.
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A network coding-aware opportunistic forwarding (NCAOF) mechanism was proposed to overcome the defects of COPE with passive coding. Taking advantage of broadcast characteristic of wireless channel, NCAOF combines the features of opportunistic forwarding and network coding. Compared with traditional methods using predetermined route forwarding mechanism, NCAOF can create more coding opportunities. In delivering packets process, the intermediate node employs the defined coding gain function to evaluate how much the opportunistic coding gain can be obtained if some packets are coded together. Then some packets are selected to encode together based on the computed coding gain, dynamically and intelligently. NCAOF assigns a higher dynamic priority according to coding gain function to forwarding the encoded packets than the native packets. The simulation results show that NCAOF can achieve a remarkable improvement in terms of the network throughput and packet delivery fraction for delivering packets in wireless multi-hop networks.
Numerical simulation of helicopter slung-load flow field and fins design
Ma Chao, Cao Yihua, Xu Zhongda
2012, 38(5): 654-658.
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Tow 3D slung-load models of helicopter were built by the CAD software according to the known geometry data. Fins of the first slung-load were designed with the method of mapping pictures. Through methods of computational fluid dynamics(CFD), the slung-load with fins was calculated and analyzed, and the result of aerodynamic resistance between CFD methods and theory methods had good agreement. Moreover, the second slung-load with fins of UH-60 Black Hawk helicopter was calculated through CFD methods, and the flow field interaction between fins and slung-load was investigated. By the calculation of two cases, fins were proved for ensuring the directional stability of slung-load crucially in flight. Then a design method of slung-load fins based on hypothesis of ignoring air damping force was presented, and the second slung-load fins were designed through the method. The impacts of fins on the directional stability of slung-load were consistent with the wind tunnel tests.
Method of small unmanned aerial rotorcraft altitude information fusion based on wavelet filter
Bai Lang, Lei Xusheng, Sheng Wei, Du Yuhu
2012, 38(5): 659-664.
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Focusing on the low performance of the sensors for the small unmanned aerial rotorcraft, an adaptive Kalman method based on filter data was proposed to improve the accuracy and reliability of the altitude measurement information. Using the wavelet decomposition and reconstruction filter, the high frequency noise of altitude information for the small unmanned aerial rotorcraft was eliminated. Furthermore, since the global positioning system(GPS) measurement accuracy was influenced by GPS satellite-number fluctuation, an adaptive Kalman filter was used to improve altitude measurement performance. At last, hovering flight and three-dimensional track flight test were used to verify the feasibility and effectiveness of the method.
Two-layer clustering over data stream with fault-tolerance
You Yuyang, Zhu Jihong, Yang Zhihong
2012, 38(5): 665-669,674.
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A new envolving data stream clustering algorithm with fault-tolerance characteristic was proposed named FTGDStream (fault-tolerant grid-density clustering over data stream). It introduces appropriate relaxation of conditions for discover generalised knowledge in real world data polluted by noise. First, FTGDStream uses similarity measure technology and lifting wavelet to construct synopsis HLSFTS (hierarchical lifting scheme fault-tolerant synopses) to realize online micro-cluster phase. Second, FTGDStream uses grid-density clustering technology to realize offline macro-cluster phase. High compression ratio of HLSFTS in micro-cluster reduces the computation load of grid-density clustering algorithm in macro-cluster and improves the efficiency of two-layer algorithm. Simulation in UCI data set proves that FTGDStream is able to clustering any shape in data space and suitable for dealing with high-dimensional data streams. FTGDStream is an efficient clustering algorithm with fault-tolerance.
Fusion algorithm for transient loading volume with accumulative error
Wang Xinfeng, Wang Hongzhi, Gao Minzhong
2012, 38(5): 670-674.
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In order to improve measuring accuracy of rocket propellant loading volume, an ultrasonic flowmeter and a high precision liquid-level meter were added to the original loading-system based on the single flowemeter. The relationship between the liquid-level and the volume was calibrated in advance. Thus, the loading volume was measured with three devices at the same time. Through analyzing the variation characteristic and error characteristic of the three measurement data, variance estimations of the three loading volume error were deduced respectively using time-domain estimation and data window, and the optimal weighted fusion algorithm was given using the least squares method. Practical application shows that the fusion algorithm is able to inhibit the expansion of accumulative error, offer more precise real-time loading volume data.
Process planning of aircraft skins NC trimming based on reconfigurable fixture
Hu Fuwen, Li Dongsheng, Li Xiaoqiang, Zhu Minghua
2012, 38(5): 675-680.
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For aircraft skins NC trimming based on the combination of the reconfigurable fixture (RF) and 5-axis gantry type milling machine, a process planning method was presented. Firstly, the locating principle, design configuration and positioning datum coordination of RF were introduced. Then the process planning analysis was detailed to solve the three problems: reasonable layout, accurate locating and stable fixturing. For the RF developed independently by our group, the implementation approaches were proposed for surface parts fixturing posture positioning, actuator rods strokes calculation, autonomic layout design, and workpiece loading process simulation. Moreover, a special supporting software system was developed. Using arbitrary Lagrangian-Eulerian method, the finite element simulation of aircraft skins perimeter milling was achieved. Finally, a cutting experiment of an aircraft skin part held by RF was done. The errors analysis results show that the machining accuracy can meet production requirements.
Damping assessment and improving design of blade shrouds based on contact states
Hong Jie, Yang Xin, Chen Lulu, Zhang Dayi
2012, 38(5): 681-687.
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Damping assessment and improving design of a certain type of shrouded blades were conducted by applying the damping design method of sawtooth shroud based on contact states. Contact states included contact forms and contact parameters, in which contact forms could be used to judge the rationality of structure design; while contact parameters could be applied to evaluate the damping effect according to their mechanical properties. By generally assessing and analyzing the dynamic characteristics, contact states and dynamic response of the blade, the deficiencies of shroud structure design were found, and then the optimization measures which contributed to improve the contact states and dynamic response of the shroud were also proposed, also the stable operation range of chord width was obtained. The contact states could reflect the real contact conditions of shrouds when they are working, which can be regarded as a more accurate and detailed criterion for designing shroud structure and judging damping effects.
Parameters estimation method of radial transformable airship
Xiao Zhiyuan, Li Zhengneng
2012, 38(5): 688-691,696.
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To break the crucial technical difficulties of controllable aerostat in near space, and make it possible of controlling aerostat going and returning between ground and near space, the conception of solar powered radial transformable airship was raised, and it-s parameters estimation method was given. The method was based on Archimedes theory and Li-style transformable airship theory. The self-adapting and controllable-transformation of sectional area was actualized by radial transformation of structure, net lift was changed by controlling the volume of airship. Controllable aerodynamic configuration was consistently kept through the change of volume ,thereby the controls for ascending, descending and staying of airship were actualized. Size of inside ballonet and outside ballonet were accounted by designing transformation project, length of airship was accounted by analyzing dynamics balance and energy balance. Based on study out design parameter, an overall design project for solar powered radial transformable airship was given, feasibility and practicality of the method was validated by example.
Compound control strategy for the pump-controlled-parallel-variable-displacement-motor speed system
Zheng Qi, Li Yunhua, Yang Liman
2012, 38(5): 692-696.
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Addressing the adaptive characteristics of the flow rate and the multiplying nonlinearity in the pump-controlled-parallel-variable-displacement-motor speed system, a kind of compound control architecture was proposed, in which the pressure is controlled by on the variable displacement pump and the rotational speed of each driving axle is controlled by variable displacement motor respectively. The 2-order linearized models of the pump-controlled-pressure-system and the motor-speed-control-system were derived. A pressure planning algorithm and a sliding mode control law were presented for the dynamic regulating of pressure. By means of introducing of the disturbance observer to the motor proportion integration differentiation controller, the nonlinear disturbance and unknown load disturbance can be restrained, so as to promote the steady precision under fluctuant pressure. The compound controller for a 1-pump-2-motor system of the transporter was designed. The simulation verifies validity of the proposed compound control strategy.
New range-Doppler decoupling method for FMCW ladar
Wang Qiao, Du Xiaoping, Zhao Jiguang
2012, 38(5): 697-701.
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FMCW(frequency modulation continues wave) ladar could detect moving target. It often uses 2-dimension FFT method to decouple range and doppler frequency. When detecting high speed target, different chirp period spectrum peaks are not in the same range bin, and using 2-dimension FFT method would acquire a fuzzy speed. In the new decoupling method, one fitting line was acquired from serial period-s spectrum peaks at first, and an estimated speed was achieved. Then a Doppler compensation signal based on the estimated speed was given and plus with the original IF signal. It makes the spectrum peaks of serial periods compensated IF signal are in the same range bin. By using 2-dimension FFT method on compensated IF signal, a compensated speed was achieved. And the target speed could be the sum of compensated speed and estimated speed. Simulation results indicate that the new range-Doppler decoupling method could effectively extend no fuzzy velocity of FMCW ladar, and achieve high precision of target range and velocity at the same time.
Structure design of a new cooling system combined micro channel and film cooling in the turbine blade
Sun Jining, Deng Jing, Deng Hongwu
2012, 38(5): 702-706.
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Numerical simulation was used to investigate a new compound cooling system, which combines micro channel and film cooling together in a guide turbine vane. Research was focused on the optimization design of these new organizational structures, in order to discuss the different effect on the characteristics of flow resistance and heat transfer. In these designed structures, branching channel structure in balancing cooling efficiency and the pressure loss has good effects. The computational results also show that the cooling efficiency of this compound cooling structure is higher than the cast-cooling blade. The prospect of the compound structure applied to turbine cooling system is huge.
Synthesis and properties of bisphenol B dicyanate ester resin
Xuan Lixin, Wang Zhiqiang, Wang Hongwei, Liu Yanming
2012, 38(5): 707-710.
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The preparation process of non-crystallized BBDCy(bisphenol B dicyanate ester resin) by alkaline catalyzer was researched. The structure and processing property of BBDCy monomer were characterized by FTIR, NMR, DSC and Rheometer. The dielectric property, heat resistance and mechanical properties of cured resin were also studied. The results show that the prepared BBDCy has high purity, and the gel time at 200 ℃ exceeds 100 min. This type of Cyanate has lower viscosity(η25℃=470 mPa·s,η40℃=210 mPa·s), which is suitable for RTM(resin transfer molding) processing at room temperature. After cured at 250 ℃, the dielectric constant of resin is 2.75, and the dielectric loss is 0.007 at 10 GHz. The cured resin exhibits excellent comprehensive with the glass-transition temperature is 299 ℃, the flexural strength is 174 MPa and the flexural modulus is 3.2 GPa.

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