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2009 Vol. 35, No. 11

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Optimization method of schemes of engine groups based on system reliability
Huang Min, Yang Jun, Zhao Yu, Tang Suping
2009, 35(11): 1287-1289.
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The power equipment of a large system consists of three engines, which has two kinds of design scheme: cold standby and down-rating. The cold standby design scheme is that two engines run in power rating and the left one is reserved; after one failure, the cold reserved engine is switched. Yet the down-rating design scheme is that three engines work at the same time, once one fails, the other two run in power rating. On condition that each engine-s life distribution follows the different Weibull distributions, the reliability models were established for these two design schemes. Based on the life distributions of engines in power rating situation and down rating situation, the time-varying reliability curves of these two design schemes were given. Then according to the comparison with the two design scheme-s reliability curves with time varying, the better design scheme was chosen. At the end, the example shows that the method is reasonable.
Tank self-pressurization process of N2O monopropellant micro-propulsion system
Sun Wei, Fang Jie, Cai Guobiao
2009, 35(11): 1290-1293.
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A ground experimental system was built to study the propellant-tank self-pressurization process of the sub-Newton-thrust N2O monopropellant propulsion system. Numerical simulation using a three-region lumped model was conducted to simulate the same process as well. Simulation results under adiabatic wall condition agree well with the experimental data, which preliminary testifies the validity of the three-region lumped model. Both experimental and simulation results show that the heat compensation for propellant-tank is necessary during the propellant self-pressurization supply process of the sub-Newton-thrust N2O monopropellant propulsion system, in order to keep stability of the tank pressure. It is also found that the initial filling factor, the volume of the tank and the propellant flowrate have great effects on the decline velocity of the propellant-tank pressure.
Attitude control technology of new-generation launch vehicles
Wu Yanshen, He Linshu
2009, 35(11): 1294-1297.
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A detail analysis was presented for attitude control design of new-generation launch vehicles. First, rigid body dynamics models and fluid sloshing dynamics models were developed based on Newton-Euler equations, and then elastic dynamics models which suggest a potential for interaction between attitude control and the structural dynamics of the vehicle, was investigated based on finite element method. According to dynamic models, attitude control system was designed. Toward the end, the method to reduce aerodynamics loads and fault tolerance design was aimed. In order to enhance the reliability of launch vehicle, fault-tolerant reconfiguration system was designed, and servo system fault influence on attitude control system was considered. Accelerometer feedback was used to reduce the aerodynamic lateral loads caused by in-flight atmospheric. All the results derived form above research are well suit for attitude control design of new-generation launch vehicles.
Simulation of near-space airship based on wrinkle during ascent
Ma Yunpeng, Lü Mingyun, Wu Zhe, Liu Dongxu
2009, 35(11): 1298-1301.
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The material of the near-space airship film is nonlinear,anisotropic,viscoelastic and incompressible.Wrinkling will be present as the airship rises and inflates in the atmosphere.The expanding wrinkles can influence stress and strain of the film.Meanwhile,it can change dynamic action and thermodynamic distributing of film in the space environment.The principal stress-principal strain criterion for predicting the wrinkle states and the constitutive matrix equation with modified wrinkle unit were used to analyse wrinkle areas.The simulation result of the new method is more conform with the testing value through the test on the ground.An effective analysis method is provided for the design of the stratospheric balloon and near-space airship.
Relative position modification of SVM’s optimal hyperplane
Zhou Hao, Li Shaohong
2009, 35(11): 1302-1305.
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Through releasing the equal-margin constraint in the standard support vector machines (SVM), keeping the sum of the binary-class function margins, a new SVM was gotten within the framework of SVM. The separating hyperplane of the new SVM can be adjusted as per the distribution of the binary-class samples, and its dual express is same as the standard SVM. Thus, the SVM was further improved theoretically. On the basis of the new SVM, a concrete algorithm, variance modification algorithm, was proposed. In the variance modification algorithm, the binary-class margins are in proportion to the standard deviation of binary-class samples. The goal of adjusting the optimal separating hyperplane as per sample-s variance is attained through the variance modification algorithm. Statistically, errors are reduced through the variance modification algorithm, while the computational complexity is not increased much.
Computer analysis of transport aircraft oxygen system based on Flowmaster
Tu Yi, Lin Guiping, Li Guodong
2009, 35(11): 1306-1310.
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Transport aircraft oxygen system was discussed, and a computer analysis model of oxygen system was established in order to analyze the flow and distribution of oxygen in the whole pipeline network. This system was comprised of three parts. They were high pressure oxygen source, aircrew oxygen supply points and cabin oxygen supply points. Separate models were established before the single system. Several special components of oxygen system were created using the external component models in Flowmaster, including the oxygen regulator, pressure reducer and quick-don oxygen mask. It made the designer more convenient to create new system models for different pipeline networksdesign. A computer analysis of the oxygen system was also performed with a given flight assignment using this analysis model,and the simulation results show the oxygen consumption and the flow rate of each oxygen supply points. It was used to verify that the system meets the design reguirements.
Optimal design of broadband matching network for electrically small antennas
Chen Aixin, Zhang Yanjun, Jiang Tiehua, Su Donglin
2009, 35(11): 1311-1314.
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A novel network topology for electrically small antennas was presented and verified successfully. An optimal design approach which combines the real frequency method and the direct numerical optimization was used to design the broadband matching network. According to the characteristic of an electrically small antenna, a network topology which can improve the efficiency of the electrically small antenna observably was designed with two methods of full-band and piecewise-band frequency matching, and the design result was computed and validated with simulation software. Finally, the two methods were compared. Results show that the voltage standing wave ratio of the antenna is below 2.5 and its efficiency is above 30% in 100~180MHz by the optimal design. The proposed network topology is especially useful in the matching of electrically small antennas and allows a good prospect of application on the designing of broadband matching networks for electrically small antennas.
Design of flight control system based on inverse dynamics and center of gravity estimation
Zhang Jing, Shen Gongzhang, Yang Lingyu
2009, 35(11): 1315-1319.
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Due to the center of gravity varying over a specified range, the aircraft may deviate from its known dynamics, thus bringing special problems to the attitude control system. A synthesis approach based on in-flight estimation of center of gravity position and the inverse dynamics was proposed. First of all, a six degree-of-freedom flight dynamics model of aircraft with center of gravity offset was built. Based on the above model, the inverse dynamics in analytical form was obtained by deducting the dynamic equation. The estimation of center of gravity location could be obtained by the initial and updated weight data. As in-flight estimation of the center of gravity position could be utilized effectively, the simulation results demonstrate good control performance under various possible conditions of center of gravity offset. The proposed method is also clear and easy to implement.
Integrated reconfigurable flight control method for aircraft with multiple control effectors
Zhong Youwu, Yang Lingyu, Shen Gongzhang
2009, 35(11): 1320-1324.
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An integrated reconfigurable flight control design method, combining passive reconfigurable flight control with active reconfigurable flight control, was presented for enhancing flight safety. The robust flight control law was designed by the trajectory linearization control method. In addition, the concept of management of control effectors was proposed to regulate the remaining control effectors. The control reconfiguration under control effector failures was achieved by optimal basis-sequence control allocation method which recombined the available control effectors as bases of multidimensional space and sequenced them according to the control objective. The simulation results indicate that the integrated reconfigurable flight control system can deal with some typical failures of control effectors. And the control commands can be followed with relative good handling quality under control effectors failures.
Semantic Web service discovery based on WordNet ontology and PLSA
Xing Shaomin, Zhou Bosheng, Chen Tianying
2009, 35(11): 1325-1329.
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A semantic Web service discovery based on WordNet ontology and PLSA (Probabilistic Latent Semantic Analysis) was proposed. Firstly, the operation name, input parameters, output parameters and the query request were annotated by WordNet ontology. Then the annotated output parameters were taken as term set, and web services as document set to construct a vocabulary-document matrix. After that the query request was taken as service and was injected into the PLSA model to determine its category. Secondly, in this category, a mapping table was established. The output parameters of services were taken as map key, and services list which contained the output parameter was taken as the key value for the map. Each output parameter of query request could match the map keys which were similar to themselves. According to the matched map key, the corresponding list of services would be identified, and then the service set that was compatible with QoS requirements also would be identified. Finally, the final service result set would be acquired according to the query request input parameters. Testing data set including 415 web services was used to make an experiment for this method. Results show that not only the performance is better than other methods but also R-precision and recall rate have been improved.
Infrared signature simulation model for space objects
Li Fubing, Xu Xiaojian
2009, 35(11): 1330-1334.
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Based on specified three-dimensional scene, an infrared signature simulation model for space objects was developed. Firstly, an object was geometrically modeled and decomposed into micro-elements in three-dimensions. Formulation for surface heating of the object with micro-motion dynamics from the sun and earth was derived. Energy dissipated into space from outer surface as well as the thermal exchange between facets of inner surface was calculated. In this way, three-dimensional thermal conduction of a ballistic object constructed with multi-layer materials was calculated, and the micro-element temperatures were obtained using Gauss-Seidel iteration. Then, radiant components including self-emitted radiation and surface-reflected radiation from the sun and earth in mid-long wave infrared band and long wave infrared band were calculated. It is seen that, because of the sun heating, temperature difference along the circumference is obvious when the object moves without spinning motion in space. Such difference becomes trivial when it undergoes spinning motion.
Correction of conservative smoothing approach used in SPH method
Long Liping, Zhang Jianyu, Zhao Libin
2009, 35(11): 1335-1338.
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The conservative smoothing approach (CSA) is a kind of methods which is very efficient for eliminating the instability of traditional smoothed particle hydrodynamics (SPH) method. Research discovered that total physical quantities of system (such as mass, moment and energy) were no longer strictly conservative in each time step with the use of CSA. The calculated value fluctuated around the theoretical value with time and affected the result precision. Correction of CSA(CCSA) was proposed. Used CSA to smooth the physical variables obtained from SPH governing equations and then used CCSA to weighted average the change of the physical variables to each neighbor node, thus ensured the conservation of total physical quantities of system (such as mass, moment or energy) in each time step. Owing to reduce of the excessive smoothness which CSA acted on physical variables, calculation accuracy was improved. Physical meaning, theoretical derivation and numerical test show the efficiency of this correction.
FPGA-based hardware-efficient architecture for variable block-size motion estimation
Wang Rui, Jiang Hongxu, Li Bo
2009, 35(11): 1339-1343.
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To improve the hardware efficiency of the FPGA-based(field programmable gate array based)architecture for variable block-size motion estimation, a novel architecture was proposed, which was optimized in both area and speed. This architecture introduced RAM-based SAD(sum of absolute differences) accumulators, which had better performance than register-based combiner in both area and speed. To improve the speed of SADs’ comparison and support partial difference eliminating algorithm, the architecture adopted a systolic comparing chain, which substituted for the bus-based comparator used in former designs. Based on Virtex-II family FPGA from Xilinx Inc., the proposed architecture consumed only 2261 slices, with the clock frequency as high as 164MHz. It means that the architecture could process standard-definition format video with 16×16 search window in real-time. Compared with similar designs, the architecture could save the area by 77% and increase the speed by 218%.
Reentry guidance law design for RLV based on predictor-corrector method
Li Huifeng, Xie Ling
2009, 35(11): 1344-1348.
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A new on-line guidance law designed based on predictor-corrector method and quasi-equilibrium glide condition (QEGC) for the reentry of hypersonic reusable launch vehicles (RLV) was presented. This advanced guidance law can generate reasonable bank angle profiles which can simultaneously satisfy the target accuracy and the path constraints such as heat rate flow, normal load and dynamic pressure. After establishing the 3DOF dynamic equations and specifying the initial states, target accuracy (CEP) and path constraints, the predictor-corrector method and quasi-equilibrium glide condition were explained in detail. The predictor-corrector method was used to generate the basic reentry guidance law for RLV, and the QEGC was used to modify the bank angle profile so that it can satisfy all path constraints. Finally, the Monte Carlo simulation was used to evaluate the performance of the guidance law under uncertain initial states. The simulation results show that this guidance law not only works accurately and fast but also has a high robustness.
Well-to-wheels analysis of large-scale bus diesel fuels
Gao Youshan, Li Xinghu
2009, 35(11): 1349-1352.
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Well-to-wheel assessment was used to evaluate the energy utilization and greenhouse gas emissions from crude oil extraction, transport, refining, namely well-to-tank (WTT), to vehicle operation, tank-to-wheel (TTW) for large-scale bus conformed to first and second phase of the fuel consumption limits.Statistical data was analyzed in WTT, test data was analyzed in TTW. Results shows that the energy consumption and greenhouse gas emissions in WTW were respectively 1.151 and 1.153 times that in TTW. Energy consumption proportion of crude oil extraction, transport, refining was respectively 6.7%, 0.42% and 6.1%. Greenhouse gas emissions proportion of crude oil production, transport and refining was respectively 1.92%, 1.42% and 9.97%. The first phase of the fuel consumption limits can reduce energy consumption and greenhouse gas emissions by 12% and 11.81% respectively; while the second phase can reduce energy consumption and greenhouse gas emissions by 16.91% and 17.67% respectively.
Fuel thermal management system of high performance fighter aircraft
Gao Feng, Yuan Xiugan
2009, 35(11): 1353-1356.
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For improving the character of high-performance fighter aircraft, fuel thermal management system (FTMS) was put forward. FTMS uses fuel as the main heat sink of environmental control system (ECS) and other systems which need to be cooled. Thermal management system of F-22 fighter aircraft is a typical applied case. Taking F-22 FTMS as an original version, the research method of thermal management system were analyzed. By using MATLAB simulation tools and S-function, static simulation and dynamic simulation modules of the system components were built up in order to get the simulation platform of FTMS. This platform could estimate the system performance and the fuel penalties. The simulation results show that FTMS can work better than the air cycle system (ACS) and satisfy the needs of high-performance fighter aircraft. FTMS will be one of the options for designing thermal management system of high-performance fighter aircraft.
Multidisciplinary optimization of control-aerodynamic-stealth for flying wing aircraft design
Sun Yijie, Shen Gongzhang
2009, 35(11): 1357-1360.
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Flying wing is a widely applied configuration for advanced military aircraft. Not only should aerodynamic and stealth requirements be taken into account at its conceptual design stage, but also the flight control system should be well designed. A flying wing aircraft was investigated, and the strategy and methods for integrated control-aerodynamic-stealth were studied. A new flow suitable for conducting multi-objective optimization in each discipline-s subspace was proposed. Design variables in subspace were assigned based on disciplinary analyses, and then system level design variables were formed by variable synthesis. According to the characteristics of flying wing configuration, control allocation based control system architecture was adopted, and time domain indexes were used as objectives and constraints in control discipline. Results of optimization show the effectiveness of new methods, which supply a feasible way for incorporating control discipline into the multidisciplinary design optimization of flying wing configuration aircraft.
CMAC neural network for the rudder dynamic load simulator of unmanned aerial vehicles
Yang Bo, Wang Junkui
2009, 35(11): 1361-1365.
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In order to solve the nonlinearity and the surplus torque disturbance in the rudder load simulator of the unmanned aerial vehicles, a hybrid controller was proposed with the cerebellar model articulation controller(CMAC) network and the traditional proportional-derivative(PD) controller. The CMAC can simulate the nonlinear continuous function with high approximation and high speed learning rate which is suitable for the real time control of nonlinear systems. In the hybrid controller, the CMAC performed the feed forward control and the PD controller realized the feedback control to ensure the accuracy in process of the control. The instability of hybrid controller was discussed and analyzed, the application of credit-assigned and adaptive learning rate CMAC hybrid controller was researched and a simple one-input and one-output CMAC hybrid control method was proposed. The simulation results show the method has settled the unstable problem of the hybrid controller and effectively improved the system dynamics with high robustness.
Method for aerodynamic and structure integrative design
Ma Tielin, Ma Dongli, Zhang Shuo
2009, 35(11): 1366-1370.
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In order to apply aerodynamic and structure integrative design to engineering practice, a concurrent subspace optimization design method based on Pareto genetic algorithm(CSSODM-PGA) which is much more suitable for aerodynamic and structure multidisciplinary design optimization is brought out based on the traditional concurrent subspace optimization(CSSO) algorithm and the analysis of characteristics of aerodynamic and structure integrative design. The CSSODM-PGA method developed in this study imports the method of the design of experiments (DOE) in response surface methodology (RSM), the subspace design concept in subspace optimization, and the Pareto genetic algorithm (PGA) in system level optimization. The developed method was used on an aerodynamic and structure multidisciplinary design optimization of a wing, and a Pareto front was obtained to give the decision-maker a more useful information.
Image transmission over multipath fading channel using joint source channel coding modulation
Wang Zhe, Zhang Xiaolin, Chen Lei
2009, 35(11): 1371-1374.
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For multipath fading channel, an image transmission method which combines wavelet transform and orthogonal frequency division multiplexing (OFDM) adaptive modulation was proposed, and the algorithm for joint source channel optimal allocation of channel bandwidth and power was presented as well. Following the presentation of system structure, the problems such as the implementation and distortion estimation of image transmission based on wavelet transform over noisy channel, and optimal bit-power allocation for multi bit error rate (BER) OFDM adaptive modulation were modeled and analyzed, modeling and analysis facilitate the combination of source quantization coding and OFDM adaptive modulation, and a joint source channel optimal bandwidth and power allocating algorithm was also developed. Simulations and analysis show that the image transmission using joint source-channel coding modulation over multipath fading channel can be achieved with small coding complexity and delay, and performance can be improved due to joint source-channel optimal allocation of bandwidth and power.
Spacecraft automatic test and spacecraft test language
Sun Bo, Ma Shilong, Yu Dan
2009, 35(11): 1375-1378.
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By the analysis of the spacecraft automatic test demands, the characteristics of test language for spacecraft automatic test were summed up, and two types of statements of spacecraft test language, that is, the regular test statements and the special test statements were given based on the analysis of test operations, test processes and test architecture. In addition, in the spacecraft test language the special test statements were classified into four kinds of statements, including operation statements, data statements, time statements and control statements. The definitions and their formal descriptions of the four kinds of the special test statements were presented in detail. This language will improve the efficiency of spacecraft test business and testers of our country, and promote the researches on spacecraft automatic test.
Simulation on pressure regulator characteristic
Yu Zhongjun, Zhao Jingquan
2009, 35(11): 1379-1383.
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The pressure regulator’s structure and working process in aviation oxygen supply system (OSS) were explored and discussed. Based on reverse-type pressure regulator, combining with the theoretic structural model and dynamics of gas flow, the mathematic models for steady and dynamic characteristics were built. By the numerical simulation on MATLAB/Simulink and the theoretic analysis to regulator performance, the steady and dynamic characteristics of regulator were analyzed. The simulation results are in good agreement with those measured in the experiment.They show that the analytical models are correct and the simulation method is in accordance with the precision requirements. By using the mathematic models and the simulation method,the affection to the steady characteristic by regulator structural parameters is analyzed and the major parameter is found to affect the dynamic characteristics. The study and its conclusions are useful for the design of congener regulators and the system analyses.
Use of X-ray pulsar-based navigation method on interplanetary trajectory
Yang Bo, Guo Xingcan, Yang Yong
2009, 35(11): 1384-1387.
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It is supposed that the X-ray pulsar-based navigation method (XPNAV) can provide high-precision navigation throughout the solar system, and its utility on the heliocentric transfer orbit was discussed. The search space array method was introduced to resolve integer pulse phase cycle ambiguities between the nominal position and estimated position of the spacecraft. A description of blending the vehicle dynamics with the pulse phase differences at nominal and estimated spacecraft locations within an Kalman Filter was provided for recursive determination of vehicle position and velocity. The simulation illustrates that this method is feasible and effective for interplanetary missions.
Sliding mode attitude control using momentum exchange device
Wang Lei, Zhao Yushan
2009, 35(11): 1388-1392.
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Modified rodrigues parameters(MRP) sliding mode control law was designed considering actuator character. Spacecraft attitude dynamics with double-gimbaled control moment gyro (DGCMG) and kinematics on MRP were founded. The model uncertainties was analyzed so that whether sliding mode control can be used here is known. Then sliding manifold was chosen and the corresponding control law was presented while estimating the parameters of the controller on the base of linear system theory and Lyapunov theory. The Monte Carlo simulation proves that this controller can execute attitude control well, precisely and robustly.
Principal component analysis used in pulsed thermographic NDT of aluminum specimens
Guo Xingwang, Qidalatu
2009, 35(11): 1393-1397.
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To improve the defect detecting ability of pulsed infrared thermographic nondestructive testing (NDT) of aluminum specimens, the principal component analysis (PCA) method and its application in thermographic signal processing were studied. Some aspects of PCA, such as data preparation, algorithm and processing effects were discussed, based on the pulsed thermographic sequence processing. Experimental studies were carried out to evaluate the validity of the algorithm and detect the defects in an aluminum alloy plate. The results show that the second and third PCA images and a reconstructed image from the first few principal components have the ability to increase the defect contrast and reduce the effects of non-uniform heating, and the detection capability of pulsed thermographic NDT is enhanced. Besides, the minimum detectable corrosion rate decreases by approximately 10 percent by using PCA in detecting the imitative corrosion in the aluminum alloy plate.
Generalized multiple-revolution Lambert algorithm for solving multiple-impulse rendezvous problem
Tong Kewei, Zhou Jianping, He Linshu, Zhang Liyan
2009, 35(11): 1398-1402.
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Techniques based on a high efficient high precision Battin multiple-revolution Lambert algorithm were extended to a generalized multiple-revolution Lambert algorithm which can consider orbital perturbations. The approach is difficult to understand but is high efficient with a simple calculation flow which needs only several inner and outer iterations. A unified multiple-revolution multiple-impulse rendezvous planning framework was proposed by combining the generalized multiple-revolution Lambert algorithm and a feasible iteration rendezvous approach. A two-step optimization method was used to solve this difficult multi-variable engineering optimization problem which first utilizing a high efficient evolutionary algorithm with an analytical orbit model for global search, then a sequential quadratic programming algorithm was used with a simplified high precision orbit model for local optimization. The proposed method can guarantee to solve multiple-revolution multiple-impulse rendezvous problem with high efficiency and precision. The demonstration validates that it is very suitable for rendezvous planning problem with practical engineering constraints.
Simulation of liquid slosh in turning process of tank truck
Liu Kui, Kang Ning
2009, 35(11): 1403-1407.
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The liquid sloshing in turning process of tank truck was simulated by volume-of-fluid(VOF) model. The forces and turning moment of a single room were calculated. The results show that the maximum of Fy (force in direction y), Fz(force in direction z) and M (turning moment) increase when the centripetal acceleration increases without a baffle. When the liquid filling ratio increases, the maximum of Fy increases, the maximum of Fz and M increase firstly and decrease afterwards. When there is a baffle, as the area of the baffle becomes bigger, the maximum of Fy and Fz decrease and the maximum of M increases firstly and decreases afterwards.
Real-time performance evaluation in WDM networks for avionics
Zhou Li, Zhao Ran, Yu Hang, Xiong Huagang
2009, 35(11): 1408-1412.
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To solve real-time performance evaluation problem in avionics wavelength division multiplexing (WDM) network, a method of end-to-end maximum delay calculation during multihop period message transmitting in WDM virtual topology was provided, based on network calculus analysis theory. A network model of the wavelength routing WDM networks was built, and then the composed parts of the end-to-end delay were analyzed. Concerning the communication model of the wavelength routing WDM networks based network calculus analysis theory, a concisely analytical expression was derived for message maximum delay passing through single and multiple wavelength routers. And then treatments of the expression which resolving the problem of the overextended burst were modified to obtain the closed upper bound of maximum delay according to the actual system of avionics. Finally, the evaluated method was testified by the simulation results on OPNET.

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