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2008 Vol. 34, No. 7

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Bi-objective optimization design of civil transport wing using N-S equations
Wang Xiaolu, Zhu Ziqiang, Wu Zongcheng, Chen Zemin
2008, 34(7): 739-742.
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A bi-objective(BO) optimization method was proposed for civil transport wing design.The thickness and twist angle of wing sections along wingspan were chosen as the optimal design factors, the two goals were the lift-to-drag ratio and wing's volume at fixed lift coefficient. Navier-Stokes(N-S) equations were used as flow field solver and Powell method was used as optimization design tool,the Lockheed-AFSOR Wing A and some civil transport's wing were computed as cases.Cases on Wing A at 0.6217 Mach number condition showed that the BO optimization results were better than the single one. Case on civil transport wing at the cruise Mach number of 0.78 and the lift coefficient of 0.48 also showed that the BO optimization method could lead to higher lift-to-drag ratio and bigger wing volume. Comparing with the original wing, the BO optimal wing's maximum thickness-to-chord ratio was bigger at the root and smaller at the tip,and the absolute value of twist angles were all smaller. The BO optimization design method is better than the common single objective optimization design method,and could provide some value for civil transport engineering design.
e-Government data exchange overlay network
Liu Xudong, Ma Xiaoxuan, Xiong Zhang, Han Jun
2008, 34(7): 743-746.
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Data exchange is the kernel of e-Government. The establishment of an e-Government data exchange overlay network on application layer is one of the crucial parts of the solution to this issue. Based on the analysis of the characteristics of e-Government data exchange, an overlay network conceptual model, eGON (e-Government Data Exchange Overlay Network), was defined. The concepts of "Organizational Distance" between nodes and "Fitness" of a certain node were introduced, and a structural model, which was called DSHON(Dual Scale Heterogeneous Organization Network model),was proposed for eGON accordingly. The proposed model was based on the structure of tree and the network performance was promoted by adding shortcuts to the original tree according to the organizational distance between and the fitness of the nodes. The architecture, construction and maintenance mechanism, routing maintenance protocol and an organizational distance priority routing algorithm were developed for eGON. Simulations were performed for the proposed message routing algorithm and the results demonstrate the effectiveness and efficiency of the algorithm.
Reproject and correct optimization in determining C-arm extrinsic parameters based on geometry constraints
Wang Tianmiao, Luan Sheng, Hu Lei
2008, 34(7): 747-750.
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The precision of C-arm extrinsic parameters is critical to computer assisted surgery systems to implement the registration of X-ray image and surgery physical space intraoperatively. Feature point extraction errors may cause deviation of extrinsic parameters using current calibration methods. A projection method was adopted to literally analyze the influence of point error to the precision of extrinsic parameters and among the parameters the translation along the optical axis was found to be less convergent and prone to fall in false optimum state. A statistical projection ratio applying geometry constraints was presented as a restriction to rectify the initial parameter estimated using linear method along the optical axis, so that a coarse transformation between the world coordinate and the camera coordinate can be determined. A ‘reproject and correct’ approach was proposed to correct the estimated extrinsic parameters based on the reprojection of the physical space to images with intrinsic parameters preoperatively determined and calculate the extrinsic parameters directly without iteration. Simulation results show that this method is more robust and precise compared to the current linear calibration method.
Effect of combined impingement cooling and film cooling on hybrid cooling effectiveness
Wang Kai, Xu Guoqiang, Sun Jining, Tao Zhi
2008, 34(7): 751-754.
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The present study concentrates on the computational investigation of a new cooling configuration of a double-layer cavity in the middle section of modern turbine blade. A three-dimensional Navier-Stokes code with standard k-ε turbulence model as well as with wall functions was used to compute the flow and heat transfer characteristics for a combined impingement and film cooling configuration. The blowing ratios are from 0.6 to 2.0, and the Reynolds number based on the inlet velocity of the cooling air and hole diameter varied from 2000 to 5000. Additionally, the effect of the arrangement of both impingement hole and film hole on hybrid cooling effectiveness was discussed. Numerical results reveal that the maximum of hybrid cooling effectiveness is localized at a distance of 3.3 d and 9d from the beginning of the cavity leading edge to film cooling hole and impingement hole, respectively. For the present computational domain, a double peak distribution of the Nusselt number on impingement target was demonstrated, and the stagnant point is localized at the valley between these two peaks.
Hybrid RANS/LES model based on turbulent scale
Li Bin, Wu Songping
2008, 34(7): 755-758.
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The main difference between the inner model of BL(Baldwin-Lomax) turbulent model and the Smagorinsky subgrid model lays in the different methods to calculate the turbulent scale. The governing equations of RANS(Reynolds average numerical simulation) and LES(large eddy simulation) are of same form. A hybrid RANS/LES model is developed here based on above observations. The governing equations of RANS are solved in inner region and the governing equations of LES are solved in outer region. A blending function is used to combine inner and outer turbulent viscous coefficients. The computational cost can be reduced compared with LES model. The hypersonic flow over double ellipsoidal spheres is simulated using the present model. Comparing with the experiment and the data of RANS model, the results show that the approach is validated.
Software-hardware cooperate priority scheduling strategy for autonomous test
Zheng Wei, Meng Xiaofeng, Zhang Weijun
2008, 34(7): 759-762.
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Autonomous test is one of the key technologies for building spacecraft autonomy. For the problem of task priority scheduling in real time operation system, a mix scheduling strategy with software-hardware cooperate was presented. After analyzing the influence factors of task importance in the complex engineering background, a synthesizing estimate index of task importance was proposed to assign priorities statically. The huge task set was clustered by self-organizing feature map afterwards. Based on this work, a priority arbitrage agent was established to reassign priorities. Then the reliability criterion was introduced to realize the priority dynamical scheduling based on FPGA(field programmable gate array). The experiment shows the strategy has reference value for autonomous system to assign priority resource rationally and to schedule test task in high speed.
Evaluating failure risk for product design scheme based on knowledge model
Wang Bin, Tang Xiaoqing
2008, 34(7): 763-768.
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Considered the relationship among failure modes, a failure risk evaluation and optimization method for mechanical product design scheme based on knowledge model was proposed. The main relationship among failure modes was identified by data clustering. The method of computing the relationship coefficient of failure mode was given, thereby the relationship knowledge for failure mode could be effectively obtained. On the basis of the knowledge model of "function-failure mode-failure risk", "roof" triangle matrix and three-dimension cube were used to represent the relationship coefficient of failure mode as well as the knowledge model of "function-failure mode-failure risk-mode relationship" was set up. By means of the knowledge model, the severity evaluation method of relationship failure mode based on weighted linear synthesis was studied, and the approach to making risk priority number (RPN) of failure mode and product function was given, then the evaluation and optimization based on product failure risk knowledge for mechanical product design scheme were presented. Finally a case was studied to illustrate the proposed method.
Random modulation for fiber optic gyroscope based on four-states Markov chain
Jin Jing, Li Min, Song Ningfang, Zang Chunxi
2008, 34(7): 769-772.
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Electrical crosstalk from modulation signal deteriorates bias stability, dead band and linearity in digital closed-loop fiber optic gyroscope (FOG). A random modulation based on a four-states Markov chain was presented to attenuate the electrical crosstalk. With periodicity of sine function and equiprobability of state transition direction, the four-states Markov chain can generate two signals statistical independently, a demodulation signal and a modulation signal, and the demodulation signal is a zero-mean stochastic sequence with the value of -1 and 1 equiprobablely. So the electrical crosstalk from the modulation signal can be attenuated via correlation with demodulation signal. The random modulation was implemented by using state machine in field programmed gate array (FPGA). Simulation and experimental results indicate that the random modulation based on the four-states Markov chain can attenuate the electrical crosstalk from the modulation signal by 1×103 times, and improve bias stability, dead band and linearity of FOG.
RAIM algorithm for identifying simultaneous two-faulty satellites
Zhang Qiang, Zhang Xiaolin, Chang Xiaoming
2008, 34(7): 773-777.
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A new receiver autonomous integrity monitoring(RAIM) algorithm was proposed for identifying simultaneous two-faulty satellites. The optimal parity vector method was studied, and the results showed that the fault of one satellite may counteract the fault of the other satellite, which reduced correct identifying ratio greatly. Therefore a new approach was developed based the optimal parity vector method. For every possible two-faulty satellites combination, two new parity vectors were constructed for detecting and identifying simultaneous two-faulty satellites, using the parity vectors which were sensitive to designated satellite failure. Computer simulation results show that the correct identifying ratio of using new method is higher than that of using the optimal parity vector method, under the condition of simultaneous two-faulty satellites. With the new algorithm, the correct identifying ratio will be higher than 90%. Moreover, the new method simplifies the processing of constructing parity vector, and reduces more than 90% of the computational burden. So the new method is better for engineering implementation.
Modal parameters identification for flight vehicle based on the continuous wavelet transforms
Wu Xiaodong, Deng Zhongmin
2008, 34(7): 778-781.
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A multi-input multi-output (MIMO) method for identifying flight vehicle structure modal parameters was proposed based on the continuous wavelet transforms. The auto regression(AR)model in the wavelet domain was established by applying the continuous wavelet transform to discrete equations of motion. The coefficient matrices of the AR model, which determine the dynamic characteristics of the system, were calculated through the least squares approach. The modal parameters were then computed by solving eigenvalues of eigenmatrix constructed by these coefficient matrices. Optimization algorithm was used to improving accuracy and stability of proposed approach in process of identification. The advantages of the proposed approach over the exiting methods of applying the wavelet transform to modal parameters identification are in use of the time invariance property and filtering ability of the transform to enhance the efficiency of identification. Simulation result shows this method is accurate and stable and can be used to identify flight vehicle structure modal parameters.
Optimization design of vision display interface in plane cockpit based on mental workload
Kang Weiyong, Yuan Xiugan, Liu Zhongqi
2008, 34(7): 782-785.
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To confirm the optimization design for vision display interface of a plane cockpit in the design phase, the comprehensive evaluation of mental workload has been used. Colligating the three mental workload evaluation methods, which are main task evaluation method, physiology measure method and subjective evaluation method, the model of plane cockpit vision display interface mental workload comprehensive evaluation has been founded, the most optimized design has been selected and has been testified by an experiment. In some type plane vision interface different designs, their mental workload evaluation values were gained using the model on the landing task. The design of the mental workload value was the best one, also tallied with the design theory of vision interface in nation military criterion. During the phases of plane cockpit vision interface design, this comprehensive evaluation system could get a satisfying evaluation result. It could be helpful for the final determination of the designing scheme.
Simulation analysis of pump and valve combined EHA efficiency design
Ji Youzhe, Qi Xiaoye, Qiu Lihua, Wang Zhanlin
2008, 34(7): 786-789.
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The efficiency influencing factors of the valve control section of valve and pump combined electrical hydraulic actuator (EHA) were analyzed. The method to improve the system efficiency by decreasing the design value of source pressure was proposed. According to the working characteristics of the pump and valve combined EHA, the change of output flow, losing flow of servo valve and pump, total efficiency of actuation system and other main performance parameters caused by source pressure change were analyzed at the same working condition. The result indicates that the system efficiency is improved and the power loss caused by losing flow is reduced in some range. The rapidity and stability become better, the disturbance rejection becomes worse, so that the efficiency and performance should be considered integrated. The simulation testing of actuation system based on spring load proves the feasibility of new method.
Evaluation of engine thrust loss for canard-spanwise blowing
Wen Ruiying, Liu Peiqing
2008, 34(7): 790-793.
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The results of force measurement in low speed wind-tunnel show that canard-spanwise blowing can increase the lift of high angle of attack, delay the breakdown of wing vortex and enlarge the stalling angle of aircraft. But canard-spanwise blowing must bleed air from engine, which makes the engine thrust lost and affects the performance of aircraft. Two methods (theorem of momentum and formula of specific fuel consumption)were used to evaluate the mass loss of inlet air, engine thrust loss, and total lift of aircraft (the sum of lost lift by bleed air form engine and the increased lift by canard-spanwise blowing). The effect of canard-spanwise blowing was compared with that of the wing-spanwise blowing. It indicates that canard-spanwise blowing needs less mass of air-bleed, with fewer thrust loss and can improve the maneuverability at high angles of attack. So it is advisable that canard-spanwise blowing is an indirect vortex control technique in the future.
Design of multi-slice CT data acquisition system and its measurement
Ma Xin, Guo Hong
2008, 34(7): 794-797.
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A multi-channel, high density and precision real-time DAS(data acquisition system) design approach was presented. It based on the embedded soft core structure, and the real-time signal processing pipeline of multi-channel data buffer, format conversion, coding transmission and ping-pang operation were realized, the problem of more quantities of data, more strict timing sequence and precision of data transmission of multi-slice CT(computed tomography)in limited scan time were solved. Meanwhile, the high precise voltage source and the sensitive registers were used to simulate the input current of DAS. The virtual instrumentation based on PXI(PCI extensions for instrumentation) bus technology was put forward to test the performance of designed DAS, without extra noise involved. The approach has been applied in multi-slice CT, it can also act as an example for data acquisition system reference.
Fault prognostic algorithm based on dual estimation and particle filter
Zhang Lei, Li Xingshan, Yu Jinsong, Gao Zhanbao
2008, 34(7): 798-802.
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Supposing that system fault evolution process is expressed by a state space model with unknown slow time-variant parameters, then the fault prognostics can be formulated as a problem of estimating model states for some future time while knowing all the information about system till time step now. An algorithm based on dual estimation and particle filter was presented. This algorithm includes two major stages:on the state estimation stage, it used an iterative procedure to estimate the posterior distributions of system states and parameters alternatively based on two parallel connected particle filters; on the state prediction stage, the algorithm sampled former estimated posterior distributions iteratively and used the sampled particles to form the prior distributions of system states for some future time. Based upon above calculated results and combined with certain fault criterions, the time to failure could then be inferred by computing the probability of system failure. Comparing with the joint estimation approach, the simulation result demonstrates the validity and feasibility of proposed algorithm.
Motor speed robust control with multiplying nonlinear property
Bai Guochang, Qi Xiaoye, Wang Zhanlin
2008, 34(7): 803-806.
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The control method that combined variable speed and variable displacement is a new type of cubage control. It has the advantages of high efficiency and relative fast response. But its multiplicative essential nonlinear property causes trouble to control. To the pump controlled motor speed system with frequency inverter and variable displacement, its mathematical model was established. To the problem of essential nonlinear property, the exact feedback linearization method was put forward in the linear process, and the motor speed sliding mode control(SMC) with integral sliding surface was designed. Considering the system with multiple parameter, the parameters were variable and difficult to be determined. All this leaded to the more chatting phenomenon in the output. to debase it, the adaptive fuzzy SMC was used to improve it, and its stability was proved. The anti disturb ability and sinusoidal track ability simulation were done. The simulation results show the validity of this control method.
Digital definition of aircraft composite structures for manufacture
Zhang Lihua, Fan Yuqing
2008, 34(7): 807-811.
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In order to satisfy the data demands and requests for composite structure-s producibility of manufacture process in the composite structures- digital development environment, the whole contents of digital definition of aircraft composite structures for manufacture were summarized. The direction datum for composite structures digital models was constructed by defining direction coordinate systems. According to the difference of composite structures- Gaussian curvature, the direction coordinate systems were divided into three kinds. The definition methods and mapping rules of these three kinds of direction coordinate system were presented. The contents and classification of geometric data, relationship of composite objects to geometric data and the hierarchy of composite objects in the definition data of laminate lay-up in 3D model were studied. The detail contents and definition methods of process information were summarized, and constructing views based on the above-mentioned data classification methods were used to organize and manage the datasets of digital definition.
Early-warning of engineering-project risk model research based on maximum entropy clustering
Tang Baojun, Liu Xiaolong, Qiu Wanhua
2008, 34(7): 812-815.
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Due to most of current early-warning of engineering risk only give a alarm,but cannot forecast, engineering-project risk early-warning based on entropy optimal model was proposed. Firstly, minimum J-divergence entropy was applied to extract the risk early-warning index and to find out the most effective feature by feature extraction. Then the calculating result was classified to judge state of project with a new clustering algorithm-maximum entropy clustering algorithm. Maximum entropy clustering algorithm allocated index vectors to all of the code vectors rather than the nearest code vector with a ratio of possibility. The algorithm is an improved c-means algorithm. Finally, the case was verified to, the results of forecast were classified by the algorithm to estimate the project-s venture. The experiment results show that the improved algorithm can use to predict the project risk quickly and effectively at engineering analyses. The analytical results are basically identical with the actual situation.
Dressing performance and dressing mechanism of diamond roller
Zhang Hongxia, Chen Zhitong, Chen Wuyi
2008, 34(7): 816-820.
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Dressing of grinding wheel has especially significant effect on grinding behavior when grinding titanium alloys because of serious adherence between abrasives and workpiece material. Experiments of rotary diamond dressing of SG wheels for titanium alloys grinding were conducted to investigate the effects of different dressing parameters on the grinding operation. The grinding force, surface roughness and topography of ground surface were measured by varying dressing parameters, including axial speed, dressing depth of cut and speed ratio. Experiment results show that the grinding forces increase with decreasing of axial speed or dressing depth of cut and a better surface finish could be obtained simultaneously. The effect trend on surface roughness of dressing ratio is complex. It was found that the workpiece can obtain better surface quality ground by the wheels trued at speed ratio 0.4. Finally, the dressing mechanism of diamond roller and surface forming mechanism was discussed on the base of systematical analysis of effect on grinding operation of different dressing parameters. The results provide an experimental basis for diamond roller dressing of SG wheels in the grinding of titanium alloys.
Numerical simulation of aircraft integrated thermal management system in steady working condition
Chang Shinan, Yuan Meiming, Yuan Xiugan
2008, 34(7): 821-824.
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Steady simulation model of aircraft integrated thermal management system was established and simulation blocks were constructed on the platform of MATLAB software. Simulation was conducted for the system for different Mach numbers and different altitudes. The outlet temperature and flow flux of key components in the system were then obtained. Influences of Mach number and altitudes on temperature of each state point were analyzed. The results indicate that in the fuel subsystem, except one state point, temperature of other state point increases with the increasing of Mach number at the same altitude in different subsonic Mach number; In the subsystem of air cycle, temperature in all state points decreases and then increases with the increasing of Mach number. The results also indicate that in the fuel subsystem, except one state point, temperature of other state points decreases with the increasing altitude in the same Mach number; In the subsystem of air cycle, temperature in all state points decreases with the increasing altitude.
Camera self-calibration technique for vision system in front for teleoperation system based on pointing rotation
Wang zhifeng, Wang Zhanlin, Fu Yongling
2008, 34(7): 825-829.
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Camera self-calibration technique for vision system in front for teleoperation system based on pointing rotation is an effective method. The problem that the calibration object can not be put in front of the camera, when the teleoperation is going on and the camera parameters need to be modified can be solved by using the self-calibration. The theoretic of self-calibration was analyzed firstly, correlative examination was done secondly. In the testing process, the camera was fixed on the rotation device. The scale invariant feature transformation (SIFT) was used to solve the problem of the feature points detection and matching, and the Newton method was used to calculate. Another camera calibration method was used to calibrate the same camera, and compared with the self-calibration. The corner point of the calibration plane was detected by using the Harris corner detector. The result of the two methods is similar, so the self-calibration is effectual.
Estimation model of comprehensive index of heat stress on fighter pilots on ground
Qiu Yifen, Fu Yang, Li Yanjie
2008, 34(7): 830-832.
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Comprehensive index of heat stress(CIHS) was given to pay attention to the high temperature influence on fighter pilots, and to supply proof to take necessary protection to the pilots. According to the airport weather report thermal environment parameters of fighter cabin were estimated first, heat and mass transfer process was analyzed about thermal system concluding pilot, summer flying wear and the cabin environment, and changes of human body thermal physiological parameters were simulated, then the CIHS was calculated. The heat and mass transfer analysis software of the thermal system was developed. The CIHS estimation curve under a given weather was plotted. The high temperature cabin experiments show that calculated results about average skin temperature, core temperature and average body temperature are similar to the experimental results, they have same change tendencies, similar increments between initial and final values. The heat stress early-warning results are the same. The deviations between experimental and calculated results are less than 20%, so the estimation model is reliable and reasonable, can meet the application very well.
Application of time-frequency analysis to ultrasonic-guided-wave signal interpretation
Zhou Zhenggan, Feng Zhanying, Gao Yifei, Zhu Xuan
2008, 34(7): 833-837.
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Ultrasonic guided wave is a kind of non-stationary signal and characterized by disperse. Its frequency spectrum variation can not be traced with traditional methods in time domain and frequency domain respectively. To solve the problem, the non-stationary characteristics of guided waves were studied, the theory of STFT(short-time Fourier transform) was introduced, the STFT and time-frequency spectrum analysis were applied to the signal interpretation of guided waves propagating in an aluminum plate and a honeycomb core structure plate. The frequencies variation of the signal propagated in aluminum plate can be analyzed as well as mode conversion and precise group velocity. Due to energy leakage, A0 mode propagates just in short distance in honeycomb core structure plate when the excitation center frequency is 1.5MHz, which results in that mode conversion can not be done well. The results show that in further distance can the STFT method be applied to not only the frequency spectrum analysis and mode identification of guided waves but also an accurate measurement of their group velocity.
Fast RCS calculation technique for targets coated with multi-layer RAM
Wang Yong, Xu Xiaojian
2008, 34(7): 838-843.
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A fast radar cross section (RCS) calculation technique for targets coated with multi-layer radar absorbing materials (RAM)was presented. The targets were modeled as a combination of facets and wedges. Physical optics (PO) method and impedance boundary condition (IBC) were used for RCS calculation of coated facets. Physical theory of diffraction (PTD) combined with method of equivalent edge current (MEC) was applied for the scattering computation of coated wedges. During the RCS calculation, matrices of reflecting coefficient were pre-calculated and stored. This greatly improves the speed of scattering calculation. RCS of single-layer and multi-layer coated plates and typical revolving solids were calculated, demonstrating that results have good agreement with those in reference. Further results of complex target show the validity of this method in improving accuracy and computing speed.
Low voltage NMOS bulk-biased folded-cascode Gilbert mixer
Song Dan, Zhang Xiaolin, Xia Wenbo
2008, 34(7): 844-848.
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By using the bulk-biased technology and folded-cascode approach, the problem of stacking input-and switching-transistors within 0.8V supply voltage was solved. A low voltage N channel metal-oxide-semiconductor (NMOS)bulk-biased folded-cascode Gilbert mixer (BBFCM) was implemented in a SMIC 0.18μm CMOS process. The mixer was used in some double-system receiver, which includes the global position system(GPS) system. In order to test the performance of the mixer, take the GPS signal for example:the frequency of the radio frequency (RF) signal, local oscillator (LO) and the intermediate frequency (IF) signal are 1575.42MHz,1570MHz and 5.42MHz, respectively. Measurement results show that the mixer features a conversion gain (Gc) of higher than 15.66dB, a dual sideband (DSB) noise figure of 16.5dB, an input 1dB compression point (P-1dB) of approximate -10dBm, and consumes approximate 1.07mW at a power supply voltage of 0.8V.Although the mixer consumes very low power, it still provides reasonable gain as well as linearity. The mixer can be applied to the electronics system within the realm of the aviation aerospace.
Estimation method for inadequate fatigue test result of structures with multi-similar-details
Bao Rui, Zhang Jianyu, Fei Binjun
2008, 34(7): 849-852.
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A method for estimating fatigue life distribution parameters with inadequate result obtained by fatigue test of structures with multi-similar-details was proposed. Based on the assumption that fatigue life follows the log-normal distribution and 2-parameter Weibull distribution respectively, the relationship of two kinds of distribution parameters, one was adopted to describe the single detail fatigue quality and the other was gained by inadequate test results of multi-similar-detail structures, was discussed. The analysis indicates that there is a significantly difference between the two kinds of parameters, however a determinate function of the amount of details can be obtained to describe this relationship. The way of estimating single detail fatigue distribution parameters via inadequate data was presented. Numerical simulations were conducted to analysis the effects of number of specimens and the amount of details on the estimating results, which shows that when the amount of details is not very large, it is the number of specimens, but not the amount of details, which has great effect on the dispersivity of parameter estimation.
Analysis of piezoelectric ceramics PLZT based on ANSYS
Liang Lei, Wang Shaoping, Cao Feng
2008, 34(7): 853-856.
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In order to avoid the defect in traditional analytic method and the finite element analysis (FEA)used in the analysis of piezoelectric ceramics, FEA software ANSYS was introduced to analyze the characteristics of lanthanum-modified lead zirconate titanate (PLZT) ceramics. The software ANSYS and its coupled-field analysis function were introduced. The ANSYS model of PLZT was built and based on the model the static and dynamic performances of unilateralism, multilayer and bimorph PLZT were analyzed. The displacement output of unilateralism was linear with applied voltage and force load. The displacement output of multilayer was less than the theoretical output because of the deformation of the adhesive layer between each two layers of PLZT. The deformable magnitude of bimorph calculated with ANSYS was very close to the theoretical results by comparing with each other. So ANSYS software can be used to build solid models, employ geometrical dimensions and material characteristic parameters at piezoelectric devices analyses. Aiming at different devices, it just needs modify parameters, and the program has good currency.
Topological structure optimization of medical hybrid robot based on dexterity
Yun Chao, Tang Can
2008, 34(7): 857-860.
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The current methods for dexterity analysis of medical robot were summarized. With numerical approach based on service sphere, dexterity calculation for 5R serial robot and for 4H parallel robot was implemented, and each task dexterity was obtained. Because of kinematics-complexity of hybrid redundant 9-DOF robot, and also because of being difficult to gain analytic solution of inverse kinematics, the displacement manifold for serial robot and displacement manifold for parallel robot were provided. At the same time, the displacement manifold for hybrid robot was deduced. In terms of above investigation, the dexterity analysis method was put forward, namely method based on Riemann manifold. The general analytic expression of hybrid robot dexterity was defined. On the base of area calculation for circumscribed ellipsoid surface of Riemann surface, a conclusion that hybrid robot dexterity is much greater than the dexterity needed for CT-guided surgery was drew. A novel idea for analysis and measurement of dexterity which is an important performance for hybrid robot in minimally invasive surgery was provided.
Identification of coaxial helicopter dynamic system with elman neural networks
Xi Haijiao, Zhang Xiaolin
2008, 34(7): 861-864.
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A modified elman neural network according to the dynamic & kinematic equations of helicopters was established, the training algorithms for the neural networks(NN) was derived, and the training steps and their realizations were provided. From the telemetry data collection of real trial flights of a type of helicopter, the data of typical flying attitudes were exploited to train the NN and calculate the elements of associated weighted matrix, thus the NN for dynamic analysis against the helicopter was obtained. To illustrate the NN effeteness, the vertical operation response in the constant velocity forward flying attitude was simulated, comparing simulation results with real trial flight data shows that the NN basically reflects the real dynamic behavior of the helicopter.

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