共查询到20条相似文献，搜索用时 31 毫秒
1.
Aiming at the questions of raceway section two dimension temperature distribution from two dimensional image accumulated by three dimensional radiation space and three dimensional temperature reconstruction error caused by limited charge coupled device (CCD) sensors for a sudden spread combustion chamber, the two dimension rectangle interpolation virtual CCD sensor installation algorithm is provided as a new technology for solving the difficulties of installing more CCD sensors and filtered back projection reconstruction error caused by limited projection numbers. The radiation intensity projection data got from flame image collected from the installed CCD sensors and computed virtual CCD sensors is interpolated for filtered back projection to computer intensity distribution and calibrated bi color method is used to calculation temperature in raceway depth direction. The results of experiments on a mini type coal gas furnace and practice test showed that the algorithm is accurate and credible and realized the on line monitoring for sudden spread combustion chamber raceway depth direction. At the same time, the useful information is provided for further studying combustion working state for the sudden spread combustion chamber. 相似文献
2.
Computation method of magnetic field inverse problem on grounding grids fault diagnosis 总被引：1，自引：0，他引：1
Grounding grids are the guarantee of substation running safety. The fault of grounding grids is a threat to people and equipment in substations. A method to diagnose the fault of grounding grids based on magnetic field inverse problem. The inverse problem of magnetic field is established by injecting and extracting a low frequency current. The morbid of inverse problem is solved through regularization and Newton iteration method to obtain the distribution of the mesh currents. The approximate distribution of the magnetic field is calculated to diagnose the fault of the grounding grid. A 4×4 substation grounding grids is taken as an example. By comparison of the forward problem result, the error is under 3%, so the prposed method of inverse problem is verified. The selection of measurement point is discussed, and 40% of the number of meshes is accounted to approximate the real distribution of the magnetic field on the grounding grids. 相似文献
3.
A new method is introduced to measure the conductivity of brain. This method uses magnetic excitation to induce eddy currents inside the brain matter and measures the magnetic field caused by the induced eddy current. The theoretical basis of this method is analyzed and the measurement system is introduced. The aufhors do the experiment and draw a conclusion that the method provided is feasible. 相似文献
4.
Effects of transverse rotating magnetic field on thermocapillary flow under microgravity 总被引：1，自引：0，他引：1
Semiconductor melt is electrically conducting, which makes it possible to apply magnetic fields to control the thermocapillary convection induced by surface tension in the floating zone under microgravity, and ultimately to control grown crystal quality. In the present paper, based on the comparison between the transverse static magnetic field and the rotating magnetic field(RMF), we focuses on the effects of RMF on thermocapillary convection. Results indicate that in the RMF, the induced Lorentz force is effective in stirring the melt in the azimuthal direction and suppressing axial convection, and both effects are beneficial for the three-dimensional melt convection returning to a steady axisymmetric flow. The RMF is a promising method for convection control in floating zone for semiconductor crystal growth. 相似文献
5.
A low-complexity blind adaptive receiver for ultra-wideband (UWB) systems in the presence of both multiple access interference (MAI) and inter symbol interference (ISI) is proposed, which is composed of two stages. In the first stage, a reduced-rank algorithm based on the multi-stage Wiener filter (MSWF) is considered to suppress the MAI and extract multi-path components. Channel estimation using the projection approximation subspace tracking with deflation (PASTd) algorithm and multi-path combining are then performed to further enhance the signal to interference plus noise ratio (SINR) of the desired user in the second stage. The simulation results show that the proposed receiver exhibits reasonably good bit error ratio (BER) performance compared with those of matched filter, conventional Rake receiver, decorrelating Rake receiver and adaptive receiver based on constant modulus algorithm (CMA). Moreover, it has faster convergence speed and less complexity. 相似文献
6.
It is an effective way for improving quality of reconstructed images that projection data are optimized in the field of Computerized Tomography (CT). For lowering the fuzziness on projection data caused by lots of factors such as noise and getting the unigue optimal reconstructed image from noisy projection data further more, in this paper, the authors develop a new model named Multicriterion Optimization Model (MOP) for optimizing projection data. The model is structured based on the theories of fuzzy mathematics and decision making, via the method of deducing projection fuzzy exponent function and square error fuzzy exponent function. The experiments for validating the model have been carried out on personal computer (PC). At first, we make simulation collecting in the images presented and add Gauss Noise into the projection data obtained by simulation collecting, Then, complete the image reconstruction from noisy projection data by the solution without optimization and another solution with multicriterion optimization. Finally, compare and analysis the different results about images reconstructed by two different solutions. The experiment results indicate that the MOP in this paper has better consistency with the theory and practice as well as obvious advantage of antinoise ability. 相似文献
7.
Based on technical aspects of ferromagnetic components crack damage detection methods and instruments applications, this paper establishes a the magnetic flux leakage analysis model for V-Cracks to get the theoretical expressions for any probe point of flat ferromagnetic component surface. We use MATLAB software programming to do a comprehensive simulation, and obtain the relation curve between magnetic flux leakage normal component Hy and crack opening width, the relation curve between magnetic flux leakage normal component Hy and crack depth, the relation curve between magnetic flux leakage normal component Hy and crack length are obtained, crack magnetic flux leakage distribution characters: normal component of Hy with zero-crossing, maximum value of tangential component Hx, and tangential component Hz with tip zero-crossing. According to the leakage magnetic characteristics obtained underby the theoretical analysis, the array type detection device and test platform are designed and fabricated, and then the plate-type ferromagnetic component with V-Cracks is detected. The experimental results show that: there is a good agreement between the three-dimensional magnetic flux leakage obtained from thesis theoretical analysis and the test results, to a certain degree the magnetic flux leakage model has directive significance for the prediction and analysis of crack parameters, and the test device be developed according to the magnetic flux leakage model is able to detect cracks in ferromagnetic components. 相似文献
8.
The edge finite element method and the imaging visualization have been studied in the forward problem of magnetic induction tomography MIT with homogeneous sinusoidal magnetic excitation. The definite equations of the forward problem were established using the electric field intensity as the vector variable. The edge FE method for solving the definite equations was introduced in detail and realized as the MATLAB program. In order to realize the visualization of MIT in imaging the intracranial hemorrhage, a real human brain finite element model was created with the human head MRI data. On the basis of this model, we realized the 3D visualization of MIT imaging in MATLAB. The research results demonstrated the validity of the definite equations and the edge FE method in calculating the forward problem. And the 3D visualization of MIT imaging with real human brain model established a foundation for the application study of MIT in imaging intracranial hemorrhage. 相似文献
9.
The Kalman filter algorithm can be used to estimate the state of charge (SOC) of power batteries, however, it easily causes divergence due to uncertain of system noise and its estimation performance is affected by model. An adaptive Kalman filter algorithm is adopted to dynamically estimate SOC of lithium iron phosphate batteries for application in electric vehicles. At first, an equivalent circuit model, appropriate for SOC estimation is built after studying battery models. Then some charging and discharging experiments are carried out for parameter identification and the results are verified. At last, the adaptive Kalman filter algorithm is used on this model for on-line SOC estimation under unknown interfering noise. Simulation results show that adaptive Kalman filter method can correct SOC estimation error caused by tiny model error online, and the estimate accuracy is higher than Kalman filter method. Adaptive Kalman filter algorithm can also correct the initial error. Full-cycle test in electric vehicles proves that the algorithm is appropriate for SOC estimation of lithium iron phosphate battery. 相似文献
10.
对复合绝缘子伞裙老化状态的评估,关系到电力系统的安全稳定运行。为了实现在工程现场对复合绝缘子伞裙的无损检测,提出了一种便携式单边核磁共振传感器的设计方案。对静态磁场的均匀度和射频线圈进行了优化,以获得较高的信噪比。以110 kV等级下不同运行年份的绝缘子为样品进行测量,使用CPMG序列对样品进行激励;采用单指数拟合和反拉普拉斯变换对核磁共振横向弛豫回波信号进行处理。结果表明,随着复合绝缘子运行时间的增加,其等效横向弛豫时间减小。因此,这种便携式单边核磁共振传感器有望用于复合绝缘子伞裙老化程度的定量分析。 相似文献
11.
基于磁性标签石块的桥墩局部冲刷监测方法 总被引：1，自引：0，他引：1
针对桥墩局部冲刷监测存在服役环境恶劣、传感器需粗放式布设等特点,提出基于磁性标签石块的桥墩局部冲刷监测方法。桥墩局部冲刷监测系统,包括磁性标签石块和磁力梯度仪。磁性标签石块采用磁性标签浇筑成混凝土石块,通过运动自由度缩减的方式,避免了基于优化搜索的磁场梯度反演中的非线性和不适定性的问题,采用磁场梯度反演磁性标签石块的三维运动,实现桥墩局部冲刷的动态监测。在磁性标签石块的模拟定位试验中,最大误差为0.2 m,最大相对误差为5%,满足桥墩局部冲刷监测的要求。磁场梯度、磁场梯度张量不变量及张量的模量均与冲刷位移场高度相关,可直接用于冲刷监测的早期预警。 相似文献
12.
The range of magnetostrictive displacement sensors (MDS) is directly determined by the electromagnetic properties of the magnetostrictive line (ML). The small measuring range of domestic MDS is caused by the ML of Fe-Ni. In accordance with the problem,applying the ML of Fe83Ga17to MDS is proposed and the possibility is demonstrated from the point of electromagnetic properties. A magnetic field model based on the fourier analysis and electromagnetic theory is firstly built,which lays a foundation for the research on electromagnetic properties. And then,the distribution of the magnetic field simulated by MATLAB helpful for wiedemann effect is obtained. The feasibility of our scheme is demonstrated by the good effect of echo signal finally. 相似文献
13.
In this paper, the vortex electric field is computed. It is caused by magnetic field subject to two dimensional change. This problem can't be solved in general physics. Two examples are listed. 相似文献
14.
[Objective] The aim of this study was to improve the cotton image segmentation accuracy in a picking robot image processing system. [Method] An image segmentation algorithm based on a fusion method of Markov random field and quantum particle swarm optimization clustering was proposed. The process of the proposed algorithm is as follows: first, transform the RGB (red, green, blue) images into grayscale; second, use it to segment these images; finally, the threshold of the connected area is set on the basis of the segmented image to obtain the target area. Then, the cotton front image and the cotton side image are selected from the images collected from different angles. The segmentation experiment was carried out by using this algorithm, and compared with the Otsu algorithm, the fuzzy C-means algorithm, the quantum particle swarm image segmentation algorithm and the Markov random field image segmentation algorithm. [Result] The results showed that the segmentation accuracy and peak signal to noise ratio of the proposed algorithm were 98.94% and 77.48 dB. When compared with the Otsu algorithm, fuzzy C-means algorithm, quantum particle swarm optimization algorithm and Markov random field algorithm, the average segmentation accuracy and peak signal to noise ratio of the proposed algorithm increased by 2.47%–4.56%, and 9.81–13.11 dB, respectively. [Conclusion] The proposed algorithm had higher segmentation accuracy and higher peak signal to noise ratio than the other algorithms tested. 相似文献
15.
In order to improve the convergence rate of genetic algorithms based on edge detection, a novel edge detection method based on a good point set genetic algorithm (GGA) was proposed. The proposed method designed the crossover operation with the theory of good point set in which the progeny inherits the common genes of the parents which represent its family so as to improve the convergence rate of the genetic algorithm. Furthermore, before the algorithm was used for edge detection, the feature space of the image grey level was transformed into the feature space of the fuzzy entropy. Dissimilarity enhancement processing next was applied to the image by using a fuzzy entropy theory to filter the non edge pixels so as to reduce the scale of the solution domain. This approach offered another efficient way to improve the convergence rate. Experimental results show the proposed algorithm performs very well in terms of convergence rate. The detected edge image is well localized, thin, and robustly resistant to noise. 相似文献
16.
During data collection,the experimental data such as curve of force versus displacement are usually disturbed by the environmental uncertain signals,which cause the data to drift greatly.Since the drift is stochastic,uncertain,and has distorted the real experimental curve severely,it brings lots of difficulties in analyzing the experiment results.In this paper,based on the characteristic of the stochastic disturbance signals,a three-phase digital filter arithmetic is given,in which the disturbance signals are filtered in each phase gradually,according to the different filter methods,and then the real curve is reappeared again.Two idiographic and different instances are adopted to prove the validity of the arithmetic at the end. 相似文献
17.
When an ignition system operates, conducted interference caused by transient voltage of the primary circuit will impact on the accumulator and the disturbance will travel throughout the vehicle via wiring. The ignition system can disrupt the Electronic Control Unit and the normal operation of other electrical devices. Spark plug gap noise simultaneously produces very strong radiation interference in a vehicle. We analyzed the changes of the ignition coil voltage and current when an ignition switch was turned on and off. A discharged circuit model of spark plug also was set up. The electric field distribution in an automobile was calculated. For these calculations, the high voltage wire was considered to be a unipole antenna. This simulation indicates that using either damped wire or adding spark plug resistance can suppress spark noise effectively. 相似文献
18.
A fracture-developed carbonate oil field in the east has a complicate oil and gas distribution in facture network at late development stage, which leads to multiplicity of favorable reservoir estimation. In view of problems above, ant colony algorithm is adapted to recognition and predict facture in this field. The ant parameters are optimized on the basis of core and image log data, and the spatial distribution feature of fracture is described, as a reticulate structure with three dominant clusters of fracture (NW, NNE & NE). Drilling leakage, production data and image log are then used for reliability analysis of fracture predict, which presents that ant colony algorithm is a practicable methodology to recognition fracture and provides a support for remaining oil distribution analysis. As a booming bionic algorithm, ant colony algorithm has great potential for quantitative fracture predict with seismic materials. 相似文献
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20.
To solve the lack of information and the error in forward and inverse problem caused by the approximation of actual three-dimensional field from two-dimensional field in electrical impedance tomography (EIT), this article presents a new EIT system. This system improves one-dimensional electrode array to two-dimensional array, and extends the solution domain to the entire three-dimensional field in order to increase the information quantity and eliminate the model error. Based on several current stimulation patterns in EIT which might yield the best sensitiveness for 3-D field, we calculate the forward problem by finite element method and the distinguishability and surface projection image method. The results show that the back electrode pattern has obvious advantages in detecting depth and precision, and has convenience in clinical application. The conclusion of this article can provide reference for the study of 3-D EIT. 相似文献