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2011 Vol. 37, No. 10

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Numerical investigation of impingement and heat transfer on inner surface of airfoil former cavity with film holes
Wu Hong, Liu Yusheng, Xu Guoqiang
2011, 37(10): 1191-1195. doi: CNKI:11-2625/V.20111013.1738.017
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Numerical simulations of impingement and heat transfer in a static airfoil former cavity with film holes were performed on conditions at different Reynolds numbers. Flows of the vortex by impingement on heat transfer mechanism was analyzed on the inner surface of leading-edge. The numerical result shows: heat transfer enhancement on the area near film holes is higher than the average value of channel at the same Reynolds number and it increases slightly with the higher Reynolds number. Wavy area of vortex generated by impingement and cross-flow extends the scope of enhanced heat transfer greatly. Suction effect of film holes flow generates an impact on impingement and enlarges the covering area of cooling air on the inner surface of leading-edge furthermore. Vortex in the vertical section of the film chamber root hinders cooling air flowing there and results in a lower cooling efficiency. While vortex in the cross-section promotes the mixing of cold and hot air near the wall with an enhancement in heat transfer.
Multiple channels extended chirp scaling algorithm for spaceborne multi-channels data processing in ScanSAR mode
Yang Wei, Li Chunsheng, Chen Jie, Wang Pengbo
2011, 37(10): 1196-1201. doi: CNKI:11-2625/V.20111013.1436.005
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Aimed at the realization of ultra-wide-swath, the operation of spaceborne multi-channels synthetic aperture radar(SAR) systems in ScanSAR mode was studied. Based on the characteristic analysis of the mode, a new method of ultra-wide-swath was presented as well as the imaging algorithm (MCECS, multiple channels extended chirp scaling). The algorithm calibrates amplitude and phase difference among receive-channels by internal calibration data and reconstructs nonuniformly sampled signal in azimuth by filter banks. After Scalloping remedy by applying the amendatory length of antenna and accurate focusing, it enabled the subswaths combination after image geocoding by solving the quartic equation. Finally, computer simulations show the validity of the algorithm.
Real-time performance evaluation in fibre channel networks
Zhao Changxiao, Tu Xiaojie, Ding Fan, Xiong Huagang
2011, 37(10): 1202-1206. doi: CNKI:11-2625/V.20111013.1517.013
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To solve real-time performance evaluation problem in fibre channel (FC) network, a network model of the FC networks was built, and then two different switch strategies were proposed to satisfy different needs of avionic networks. A method of end-to-end maximum delay calculation was provided, based on network calculus analysis theory. Delay upper bounds based on the strategies of switches were analyzed. The analysis results show that using non-preemptive priority (NPP) service strategy, compared with first come first service (FCFS) service strategy, can reduce the upper bound delay of high-priority data stream. Finally, the evaluated method was testified by the simulation results on OPNET.
Flight operations risk diagnosis method on quick-access-record exceedance
Qi Mingliang, Shao Xueyan, Chi Hong
2011, 37(10): 1207-1210. doi: CNKI:11-2625/V.20111020.1126.010
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Based on the data of quick access record(QAR), a mathematical model was formulated to find the high risk subspace-, which has high probability for a special QAR exceedance in landing stage, in the space- consisted of the flight operation indexes, such as decline rate, aircraft pitch, etc. Focusing on this QAR exceedance, data of above mentioned indexes at 20 feet radio altitude and their change ratios from 20 feet to 0 feet were considered in the method. Preliminary analysis shows that the QAR exceedance samples and the normal samples have a similar ratio in the scope with more than 62 tons total-landing-weight and less than 32 Celsius degrees landing-temperature. This result reflects that environmental factors in this scope may be not the main mechanism of this QAR exceedance. For elaborately diagnosing these samples, the objective of the mathematical model is maximum ratio of QAR exceedance; the subspace- must satisfy certain sample size. An algorithm based on golden section was provided, and threshold values of each index were found. The result would guide the pilot’s simulation pertinence training.
Dynamic response analysis of airdrop for flexible aircrafts
Wu Zhigang, Yang Chao, Jing Zhiwei, Yang Qiuyan
2011, 37(10): 1211-1217. doi: CNKI:11-2625/V.20111014.0830.002
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Airdrop of heavy cargos can produce severe dynamic loads. Excitation of the loads have wide band of frequency, which can excite many higher order elastic modes. And the dynamic response may be amplified by the aeroelastic effects. A method of dynamic response analysis of heavy cargo airdrop for flexible aircrafts was presented. The equations of motion of the elastic flexible airplanes were deduced by applying energy method and considering rigid-body modes and elastic modes. The state-space equations of airdrop dynamics were established by applying rational function approximation of unsteady aerodynamics.Airdrop response can be simulated by numerical integration, in which the results of trim analysis were defined as the initial conditions. The numerical simulation of a transport aircraft was presented, and the influence of cargo mass on airdrop dynamic response was studied. Results show that elastic aircrafts have more severe airdrop response than rigid airplanes, and heavier cargo will arouse more severe response. For the aircraft without altitude stabilizer, airdrop will induce a decrease of the flight altitude.
Mechanical behaviors of brush seals and sealing performance
Wang Zhili, Guo Miaomiao, Li Like
2011, 37(10): 1218-1222. doi: CNKI:11-2625/V.20111013.1436.007
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The brush seal design and analysis software named Field CAL which was built independently. The mechanical behaviors of bristles are the main reasons of bristles ‘low down’ and hysteresis effect. The pressure field and flow field of brush seal were stimulated and the bristle mechanical behaviors were studied. The interactions between bristle mechanical behaviors and flow field influenced the sealing performance. Based on the cantilever beam theory and the calculated pressure distribution, bristle deflections in both the axial and circumferential directions were calculated utilizing the finite element method. The calculated results were compared with experimental results. The results show that the larger pressure gradients which are formed in radial and axial directions of the outlet of brush seal can close the clearance and blow down the bristles. It can maintain the steady sealing performance, when the states of working or clearance are changed. The research results are of referential value for the design and analysis of brush seals.
Results analysis and prediction on civil aviation safety indices
Wang Yanyang, Cao Yihua
2011, 37(10): 1223-1227. doi: CNKI:11-2625/V.20111013.1727.015
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In order to predict civil aviation safety, the range prediction model was developed by using grey range prediction method, which suited for the character of less and uncertain of the safety assessment result data. The results of civil aviation safety indices were shown. According to these results, the civil aviation safety level was analyzed, which showed the function and usage of this safety assessment indices system. To demonstrate the validity of grey range prediction method, the grey prediction range model of civil aviation safety assessment was tested by actual data of China civil aviation composite safety index. By using this model, the prediction range of China civil aviation composite safety index for next year was given.
Route planning of cruise missile based on improved particle swarm algorithm
Sun Jian, Wu Sentang
2011, 37(10): 1228-1232. doi: CNKI:11-2625/V.20111013.1436.008
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Particle swarm optimization algorithm(PSO) is new type swarm intelligence algorithm after genetic algorithm and ant colony optimization algorithm,which is usually used in solving complex problems. Because its iterative formula is continuous, PSO is more suitable to solve route planning without grid. To the problem of premature frequently appeared in standard particle swarm optimization, improved particle swarm optimization (IPSO) algorithm was proposed. IPSO firstly selected elite particles and bad particles according to relevant cost function,updated velocity of bad particles according to kinetic energy loss of elite particles to avoid premature in search process. Secondly IPSO proposed velocity update strategy with failure experience of worst particles to let particles avoid bad result. Result which use IPSO in route planning of missile shows that, IPSO has better search capability in route planning application and receives smaller cost if iterations are same.
Quality of service guarantee for avionics high-speed switched network
Wang Haotian, Zhou Li, Liu Cheng, Xiong Huagang
2011, 37(10): 1233-1237. doi: CNKI:11-2625/V.20111020.1126.008
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To achieve avionics network-s real-time and high bandwidth performance, the fibre channel(FC) over wavelength division multiplexing(WDM) architecture was established, which adopt the periodical flows for real-time communication in switches, and the scheduling algorithm based on load-matching output port round(LOR)was proposed. Using only once arbitration, LOR could obtain input/output port-s maximum matching (100%). Core code of LOR was described after that, which had O(1) complexity and could be embed into hardware suitably. Finally, the experiments were conducted at network processor under time-sensitive load in term of quality of service (QoS) parameters (delay, throughput and overtime packets number), and the results show that under low load (30%) LOR algorithm has the same QoS performance with traditional algorithms (iSLIP, DRR, EDRR), but under heavy load (70%) only LOR could satisfy real-time delay constraint, and throughput of LOR is nearly more than 10% than traditional algorithms, and overtime packet number of LOR is less 100 than traditional algorithms-.
Analysis method for influential factors of aviation equipment availability based prognostics and health management
Liu Rui, Ma Lin, Kang Rui, Zou Yingzhi
2011, 37(10): 1238-1244. doi: CNKI:11-2625/V.20111020.1126.003
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The aviation equipment availability analysis method was reviewed and the influential factors of aviation equipment availability were classified as three categories.The newly increased influential factors of aviation equipment availability were analyzed through analyzing in the influence of prognostics and health management (PHM) technology to the availability. These factors were specified in term of the sources as two categories: the operate factors and the design factors. Four reasonable assumptions to simplify the simulation process. were provided. Furthermore, the design factors were divided into five categories. Combined with an example, the definitions of the simulation inputs of aviation equipment availability were given with the values of them. And the output of the simulation process is the steady-state availability under given conditions. Simultaneously, the analytical algorithm of it is pressed. Then the compositions simulation program and its flow chart were detailed described. The simulation results of the example were given by graph. At the same time the processes and conclusions of univariate analysis and multi-coupling analysis were given to verify the feasibility of the analysis mentioned.
Inter-satellite links topology scenario based on minimum PDOP criterion
Sun Hua, Hao Xiaopeng, Feng Wenquan, Yin Jia
2011, 37(10): 1245-1249. doi: CNKI:11-2625/V.20111013.1436.006
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Inter-satellite link is a critical technology for the satellite navigation system to realize its independent running. On the base of Walker(24/3/2) constellation, the visibilities between satellites and relative constraints of inter-satellite links were analyzed. After computing and determining the arrange scheme of satellites on the same orbit, the method to establish inter-satellite link topology with the minimal position dilution of precision(PDOP) value, that means the ranging precision is highest, was probed. On this basis the optimal paths between satellites and between satellites and ground stations were computed using Dijkstra algorithm. The statistics of time-delay in inter-satellite data transmission and data flow of satellite nodes show this link generation method can fulfill the pre-defined technological requirements and is practicable. Meanwhile simulate on three different strategies that are shortest path, minimal hop and balanced flow to verify the different results of the strategies.
Improved approach for digital multiple notch filter design
Wang Qiusheng, Yuan Haiwen
2011, 37(10): 1250-1255. doi: CNKI:11-2625/V.20111013.1436.009
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A digital multiple notch filter was mainly used to remove sinusoidal interferences contained in a digital signal. To remove the shortcomings in the classic methods, an improved design approach about the filter was presented. It made use of the mapping relationship between the amplitude response of a notch filter and the phase response of an all-pass filter. It converted the design problem of the notch filter to that of the all-pass filter. The basic principle and design process of the proposed method were discussed in detail. The stability and effectiveness of the presented approach were validated by a series of simulation experiments.
Critical region protection testing method for operating system shared date
Zhang Mingjie, Lei Xun, Song Heng, Li Qiang
2011, 37(10): 1256-1259. doi: CNKI:11-2625/V.20111020.1126.002
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The method for testing critical region protection was studied. A method called SVAM (shared variable address monitor) for testing critical region protection mechanism of shared variable, which is based on monitoring shared date address, was presented. The proposed testing method consists of a real-time address monitor module and a shared variables address list. When the system is running, SVAM will monitor the variable written on the address bus. If the variable is updating and the interrupt is open, the system will enter uncontrollable status, and the critical region protection mechanism is corrupted. The correctness of SVAM was verified through theoretical analysis, and the validity of SVAM was verified through an embedded real-time operating system software testing project.
System synthesis design method in system engineering process
He Fei, Yang Jianjun
2011, 37(10): 1260-1263,1270. doi: CNKI:11-2625/V.20111020.1126.005
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Based on the design process acted as a solution-finding process under certain constraints, and on analysis of the system engineering process, for a complex product, a system synthetic design method with ‘request-function-structure’ solution space and ‘analysis-synthesis-evaluation’ execution mechanism was presented, a basic process for system synthetic design was determined for complex product, and a synthetic design platform composed of integrated product and process models and a tool management architecture was established according to the system synthetic design method, thereby providing a uniform integrated platform for engineers, implementing the system synthetic design method, helping the engineers to organizing and coordinating the product design action with a whole system view, ensuring that all of the action in the whole product design process was performed based on the whole system, fully determining all technologies, function requests and physical structures by a uniform mean, and ensuring that the performance of the final system in a given environment can satisfy the original expectation of users.
CAN bus application layer protocol design for unmanned helicopter system
Zhang Lei, Zhu Ming, Wu Zhe
2011, 37(10): 1264-1270. doi: CNKI:11-2625/V.20111013.1436.012
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In order to put the CAN (Controller Area Network) into UHS (Unmanned Helicopter System) application, a universal CAN application layer protocol was developed. The problems which are data definition, telemetry, telecontrol data link bandwidth and so on in the CANaerospace V1.7 protocol application in UHS were improved. Redefining of the basic message format and the data identifier, the CANauh protocol for UHS was put forward. In order to verify the CANauh protocol, a proposal of UHS avionics system based on CAN data bus was chosen as the research object, the data on the CAN bus, data identifier distribution and bus schedule were designed and simulated by the CANoe tool. The CAN bus load on 10 ms basic period is 40.83%, data extended definition space is 67.4%, the duty factor of telemetry and telecontrol data link bandwidth is 66.7%, satisfying the requirements of UHS. The CANauh protocol will promote the CAN data bus application in new UHS, can avoid repeated design, increases the interoperability and reduces the cost of development and maintenance.
On-orbit calibration of stellar camera considering distribution of star image points
Xie Junfeng, Jiang Wanshou, Gong Jianya
2011, 37(10): 1271-1276. doi: CNKI:11-2625/V.20111020.1127.013
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Although the parameters of the stellar camera are accurate by the ground calibration in advance, they will change due to the intense vibration in the process of the satellite launch or the change of space environmental factors such as the temperature, the atmospheric pressure, etc. The on-orbit calibration method based on the spatial resection with multi-images was applied to the stellar camera. The percentage of the convex hull area out of the star image was employed to choose the stellar image with good distribution since the calibration accuracy is related to the distribution of the star image points. The experiment result indicates that the calibration accuracy based on the selected images is better than that based on all the stellar images.
Planning of CSADT with stress optimization under cost constrained
Ge Zhengzheng, Li Xiaoyang, Jiang Tongmin
2011, 37(10): 1277-1281. doi: CNKI:11-2625/V.20111020.1127.012
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In constant stress accelerated degradation testing (CSADT)scheme, there are four variables: stress levels, interval of performance inspection, sample size and number of inspection at each stress level need to be determined. However, the issue about how to optimize stress levels is seldom discussed. For optimizing the four variables comprehensively a method was proposed. First stochastic process was used to describe a typical CSADT problem. Next, under the constraint that the total experimental cost does not exceed a predetermined budget, the objective is to minimize the asymptotic variance of the estimation of the reliability of the pth quantile of product-s lifetime under use condition. The optimal plan can give the four variables mentioned above. Then a simulation example was presented to illustrate this method. Finally, sensitivity analyses of optimal plans to misspecifications illuminates that the optimal plan is quiet robust for a moderate departure from the assumed value of parameters.
Optimal safety partition design for integrated core processor under dynamical priority
He Feng, Gu Jian, Xiong Huagang
2011, 37(10): 1282-1287. doi: CNKI:11-2625/V.20111020.1127.011
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During the research on the application of partition management model into avionic integrated core processor (ICP), the reasonable partition parameters design is an important factor to ensure the mission-critical and safety-critical guarantee for the whole system. Based on the standard model, the extended model that the upper scheduler adopts the dynamical priority scheduling strategy was proposed. Through observing partition behavior during the processing busy period, the worst-case preemptive effect calculating algorithm for any given requested time length was obtained, which explains the atomic preemption behavior under the dynamical priority in detail from a more microscopic aspect. By calculating the task load for task set and considering the preemptive influence caused by the requested time length which extends to the last partition execution window for the task load, the safe partition parameters design solutions were also established for the priority based scheduling strategy in the lower scheduler. The simulation experiment shows that the safe partition parameters design algorithms have a higher efficiency than the virtual processing resource method.
Power line communication for control system of reconfigurable machine tools
Yang Dongsheng, Huan Ji, Stefan Schmitz, Karl-Heinz Wurst
2011, 37(10): 1288-1292,1297. doi: CNKI:11-2625/V.20111020.1126.007
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The communication system requirements for reconfigurable machine tools were analyzed. A new communication system based on PLC (power line communication) was proposed. The carrier frequency and bandwidth of the communication system were settled according to the channel characteristics and noise spectrum of the power line in machine tools. To deal with multipath fading, improve the spectral efficiency, and obtain a high speed data transmission, OFDM (orthogonal frequency division multiplex) was employed as means of modulation and demodulation. A PLC modem was developed. The PHY (physical layer) frame structure was defined. A field test system based on main spindle servo system was set up. The experimental results show that it achieves a data rate of 10 Mbit/s with BER (bit error rate) less than 10-8.
Sun sensor calibration based on exact modeling with intrinsic and extrinsic parameters
Fan Qiaoyun, Zhang Guangjun, Wei Xinguo
2011, 37(10): 1293-1297. doi: CNKI:11-2625/V.20111013.1435.003
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Polynomial equation fitting and simply modeling with only intrinsic parameters were generally used methods to calibrate a sun sensor, in which its accuracy was limited to 0.02° in field of view: ±60°. To improve the accuracy, a new calibration method based on integrated modeling with intrinsic and extrinsic parameters was put forward. An integrated imaging model was firstly established with intrinsic and extrinsic parameters. And then the calibration points- data were acquired by using a 2-axis rotary table and a sun simulator. Finally, a two-step procedure was presented to optimize these parameters. This method does not require initial alignment between incident light and the imaging plane, and the calibration accuracy of intrinsic parameters were immune to extrinsic parameters error by exactly separating of them. Furthermore, the calibration accuracy is greatly improved by two-step optimization. Experimental results show that the calibration accuracy reaches 0.005°(field of view: ±60°) which is 4 times of the accuracy reached by generally used methods.
Theoretical analysis on stiffness and damping characteristics of metal rubber
Zhu Bin, Ma Yanhong, Hong Jie
2011, 37(10): 1298-1302. doi: CNKI:11-2625/V.20111020.1126.004
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The theoretical research on hysteretic characteristic and nonlinear stiffness and damping characteristics of metal rubber was performed. Wire helix was considered as the micro-element structure of metal rubber by analyzing the characteristics of processing components of metal rubber. A mechanical model of wire helix was established based on the material mechanics and the coulomb friction model. The contact states of wire helix were also considered in this model which combined with the impact of friction to cylindrical compression coil spring theory. It was easy to explain the mechanism of hysteresis loop and the nonlinear stiffness and damping characteristic of metal rubber by analyzed contact states and contact numbers of micro-element wire helix. This model was valuable for the analysis of the material mechanics and the design of metal rubber. It provides theoretical support for the further engineering application of metal rubber in the field of vibration reduction.
Fast target detection based on area prediction and visual attention computation
Liu Qiong, Qin Shiyin
2011, 37(10): 1303-1307. doi: CNKI:11-2625/V.20111013.1436.004
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A new method of fast target detection was proposed with combination of area prediction and modeling computation of visual attention (VA). A rule set to predict target area was established based on the analysis of three feature parameters in three horizontal subareas: grayscale rate, entropy and its position. Meanwhile, the VA computational model was improved by optimizing the selected features and optimizing contribution weights of feature maps. Given an image to be detected, the target area was predicted according to the rule set. Then, the VA modeling computation was carried out only in the predicted areas. The experiment results demonstrate that in the task of detecting pedestrian in outdoor scene, the proposed method can reduce the detection time by 30% and enhance the detection accuracy by 9% in comparison with the traditional method.
Instantaneous phase based SNR estimation algorithm for BPSK signals
Zhang Xiaoyong, Luo Laiyuan
2011, 37(10): 1308-1311. doi: CNKI:11-2625/V.20111020.1126.001
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By studying of the characteristics of the instantaneous phase of the mixed signals of sinusoidal signal and additive white Gaussian noise (AWGN), a novel signal-to-noise ratio (SNR) estimation algorithm for binary phase shift keying(BPSK) signal was proposed. There is a nearly linear one to one relationship between the variance of instantaneous phase and the SNR, based on which the estimation of SNR was acquired by comparing the variance of instantaneous phase of the received signal with the theoretical one. The algorithm treated directly with the over sampled baseband signal, so symbol timing and synchronization, which were hard to acquire when symbol-rate is unknown or in accurate, are not needed. Computer simulations were used to test the performances of the SNR estimation algorithm. Results show that the proposed algorithm is more accurate in precision than the high-order cumulants based method and the subspace decomposition based method.
Subsystem disturbance rejection control of turbo-shaft engine/helicopter based on cascade ADRC
Sun Liguo, Wang Rixian, Sun Jianguo, Zhang Haibo
2011, 37(10): 1312-1316. doi: CNKI:11-2625/V.20111020.1126.009
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Disturbance rejection control problem of turbo-shaft engine speed was studied. A disturbance rejection control scheme of turbo-shaft engine was proposed based on increment cascade adaptive disturbance rejection control (ICADRC). For one thing, cascade control structure was used to ensure that the disturbance in the inner loop can be suppressed in time. In this control structure, gas turbine speed was controlled in the inner loop, while power turbine speed in the outer loop. For another, in both control loops the control object was compensated from disturbance in virtue of extended state observation. Finally, digital simulation of integrated helicopter/engine system shows that the new control scheme can improve the power following character of turbo-shaft engine evidently, and can enhance the handling limit of integrated helicopter/engine closed loop system.
Fast transform and frequency estimation algorithm of finite Ramanujan Fourier transformation
Guo Xujing, Wang Zulin
2011, 37(10): 1317-1320,1325. doi: CNKI:11-2625/V.20111020.1126.006
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A new Ramanujan transformation (RFT) is an arithmetic transformation based on Ramanujan sums, well adapted to the analysis of signals with fractional frequency. First, spectrum characteristic for the finite Ramanujan transform and the distribution model of Ramanujan base vectors were presented. Second, the fast algorithm for RFT was derived and the multiplication computation amount of the Ramanujan transformation with that of the fast Fourier transformation was compared. Furthermore, a recursive frequency estimation algorithm for RFT and the frequency resolution analysis had been presented. Finally, over the non-Gaussian noise, the frequency estimation performance comparison of RFT and Fourier transformation has shown that the normalized mean square error (MSE) of RFT can reach at 10-3 for the non-Gaussian noise with the SNR equal to -20 dB.
Laser triangulation based measurement about the surface 3D topography of a cup CBN grinding wheel
Chen Feng, Chen Wuyi, Chen Zhitong
2011, 37(10): 1321-1325. doi: CNKI:11-2625/V.20111013.1708.014
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The limitation of the normal measuring methods about the surface topography of the grinding wheel was discussed, and the theory of the laser triangulation was expounded. Then, a method of measuring the surface topography of the wheel using the laser triangulation was proposed and the measuring system was built. It was used to obtain the 3D coordinate data of the point on the wheel surface by scanning way. Then the 3D topography of the grinding wheel surface could be established and the 3D size of one single grain can be obtained through analyzing those measuring data with the Origin 8.0. In the experiment, the 3D topography of 0.5 mm×1.6 mm area on the wheel surface were obtained. It also indicates that the width of a wheel grain was 209.1 μm and the height was 17.3 μm.The error ratio of this measuring was about 1.00%,compared with the measuring result using white-light interfering profilometer by WYKO from the US. It is concluded that the proposed method and system is feasible and satisfied.
AFDX modeling and simulation based on discrete event method
Huang Zhen, Zhang Yongtao, Xiong Huagang
2011, 37(10): 1326-1332. doi: CNKI:11-2625/V.20111013.1436.011
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For dimensioning avionics full duplex switched ethernet (AFDX) network, discrete event method was used. Devices in the network, such as end-system and switch, were modeled by the basic network elements. The communication behavior including VL control, message framing and switch forwarding etc. was described as discrete event. Different network elements were integrated by these events, and a model of the network was composed. Based on AFDX modeling, the simulation tool was developed with C+ +. Typical AFDX network topology was used to verify the model. The simulation was verified by comparison with the theory calculus which is called network calculus. The result indicated that the modeling and simulation were reliable. Two simulation scenes with different network flow were used to analyzing the performance of AFDX. According to the simulation analysis, irregular flow generated by either end-system or switches was isolated by VL, so that it cannot take effect on the regular flow. The reliability of AFDX was verified.

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