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Liu J.-X.,Central South University | Liu J.-X.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Guo R.-W.,Central South University | Guo R.-W.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 7 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2011

In this paper, we apply Fourier analysis (including local Fourier analysis and general Fourier analysis) of multi-grid method to predict and analyze the convergence of multi-grid method used to discretize Helmholtz equations with complex-valued entries aroused in magnetotelluric problem. The Fourier spectra, which are usually complex in spectral domain, however, should be converted to real domain when visualizing the convergence behavior. The eigenvector spectra in real domain could be used to answer the slow convergence in two-grid method with Gauss-Seidel solver used on the coarsest grid. As not including boundary conditions and variant coefficients, local Fourier analysis (e.g., one-grid Fourier analysis and two-grid Fourier analysis) is difficult to give a reasonable asymptotic convergence estimate of two-grid method with a direct solver on the coarsest grid, whereas two-grid general Fourier analysis could. The Fourier analysis for five-grid method using a direct solver on coarsest grid shows that when the general higher-grid Fourier analysis is applied, the general Fourier analysis gets close to the numerical asymptotic convergence. Based on the set of general multi-grid Fourier analysis results, an empirical formula approximating the asymptotic convergence for five-grid method is derived, thus we just need to carry out the general low-grid Fourier analysis(two-grid and three-grid) on coarsest grids and approximate the asymptotic convergence with low cost.


Yan F.-B.,Central South University | Yan F.-B.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Liu J.-X.,Central South University | Liu J.-X.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Su Y.-R.,CAS Chengdu Institute of Optics and Electronics
Journal of Communications | Year: 2015

Power-consumption reduction, resource optimization and cost reduction are inevitable on geophysical instrument design. We propose a new method for serial data clock domain crossing (CDC) transmission to solve the resource utilization problem of data acquisition interface in geophysical instrument design, combining with the use of digital programmable logic chip FPGA/CPLD. This method changes the usage mode of several simple serial-to-parallel and parallel-to-serial converting registers in original design to convert the CDC serial data instead of the traditional FIFO transfer way, which saves FIFO chips or FIFO modules in programmable logic chip resources fundamentally and can realize the same function as traditional design mode. Through long time verification in practical engineering, the method we proposed can be proved to be with reliability, effectiveness and stable operation. © 2015 Journal of Communications.


Yan F.-B.,Central South University | Yan F.-B.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Su Y.-R.,CAS Chengdu Institute of Optics and Electronics | Liu J.-X.,Central South University | Liu J.-X.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection
Journal of Communications | Year: 2015

For measurement systems, guaranteeing the accuracy is the primary task and optimizing resources has strong connection with low power consumption and low cost. There is a need for smooth filtering, median filtering and some other data processing in Complex Programmable Logic Device or Field-Programmable Gate Array design of measurement systems. And the weighted arithmetic is indispensable for filtering. Combined with the characteristics of data acquisition in measurement systems, a new real-time weighted method is put forward. This method does not need to call IP core and built-in CPU. Two data registers with different bits are designed in Complex Programmable Logic Device or Field-Programmable Gate Array. Combining with the addition and shift operation of the input data with the addition and shift operation of quotient together to form the new weighted division data, this method owns the advantages of good real-time ability and high accuracy compared with the conventional division operations. And it can be used in the Complex Programmable Logic Devices without IP core, as well as in low power consumption Field-Programmable Gate Arrays. This method achieves the goal of utilizing resources according to the function realization of the measurement systems. To acquire the same function with the traditional design pattern, the feasibility and effectiveness of the method described in this article are verified through designing five-order smoothing filter test. This method has been used in a project, which proves that the method is reliable, efficient and stable in practical application. © 2015 Journal of Communications.


Yan F.,Central South University | Yan F.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Yan F.,CAS Chengdu Institute of Optics and Electronics | Su Y.,CAS Chengdu Institute of Optics and Electronics | And 3 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2015

For the focusing demand of optical platform applied in photoelectric tracking control system, such as theodolite and quantum communication telescope, a low-cost, small-sized and high-precision optical focusing control system on the basis of the guarantee performance and reliability was designed. With ARM and FPGA as the processing cores, PID optical control platform realized focusing control, according to the image-forming principle. We analyzed how to improve focusing accuracy of the optical platform and utilized the buffer operational amplifier extending the signal method to improve focusing control feedback deviation signal precision. Three kinds of feedback signal compensation methods were put forward and their comparison and analysis were done as well. An equal median compensation method was chosen to compensate the potentiometer feedback signal. This method simplified the hardware and software design without affecting the focusing time, improved the focusing accuracy and was with features of low-power consumption, easy implementation, high focusing control precision, low cost and small size. The subjective analysis was done to an image collected from the focusing experiment. The objective criterion was used to confirm the analysis. And the validity of the design was verified. This design was applied to a photoelectric tracking and detecting product, whose full focusing time was about 3 seconds at 1 μm-leveled precision. The design was with fast response as well as stable and reliable performance. ©, 2015, Editorial Office of High Power Laser and Particle Beams. All right reserved.


Tang D.,Central South University | Tang D.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Liu J.,Central South University | Liu J.,Hunan Key Laboratory of Non ferrous Resources and Geological Hazard Detection | Yang Z.,HIGH-TECH
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2014

To improve detection accuracy, simplify hardware circuits and accurately measure response parameters on geologic body of main frequencies in 2n composite frequency signals, a digital coherent detection system was designed based on digital coherent detection principle. The hardware adopts high quality processor STM32F103RD, 24 bit high precision ADC ADS1271 and GPS to realize signal acquisition. The software realizes response parameters detection through A/D sample rate processing algorithm, reference signal discretization processing algorithm, GPS synchronization rules setting algorithm and coherent detection calculation algorithm based on hardware platform. The results show that the digital coherent detection system can accurately detect response information on simulated geologic body of main frequencies in 2n composite frequency signals. It has good consistency, repeatability and high ability to resist temperature interference. And it can efficiently improve detection accuracy and decrease error. So this system can meet detecting requirements of current frequency domain exploration instruments in geophysical field, and it has broad application prospect.


Liu J.-X.,Central South University | Liu J.-X.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Cao C.-H.,Central South University | Cao C.-H.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 2 more authors.
Wutan Huatan Jisuan Jishu | Year: 2012

With the Grapher7. 0 Scripter by Scripter Basic language programming for secondary development, Geophysical profiles can be batched automatically. Firstly, This paper describes the interaction process of the Grapher7. 0's Automation Technology; Then uses the fortran programming to preprocess the batch of raw data, and shows scripter basic language programming to generation the color profile; Finally, drawing results was analyzed by geophysical practical examples. Obviously, this method provides a simple and effective way to develop the software of geophysical profiles.


Liu J.,Central South University | Liu J.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Tang W.,Central South University | Tang W.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2014

Finite element equations were given for 2.5-D frequency domain controlled-source electromagnetic (FCSEM), and the solving process of stiff matrix of finite equations was explained, based on rectangle meshing and biquadratic interpolation. The chosen schedule of wave number was researched and a high precision wave number select scheme was reached. Using this algorithm to compute for a homogenous half space model, comparison results between analytic solution and numerical solution verified the correctness of this algorithm. Finally, two 2-D geo-electric models were computed, and the contour maps both for apparent resistivity and phase of TE and TM mode were obtained. The results show that the forward modeling results can reflect anomaly on different levels, which furtherly verifies the effectiveness of this algorithm modeling for 2.5-D FCSEM.


Tang W.,Central South University | Tang W.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | Liu J.,Central South University | Liu J.,Hunan Key Laboratory of Non Ferrous Resources and Geological Hazard Detection | And 2 more authors.
Jilin Daxue Xuebao (Diqiu Kexue Ban)/Journal of Jilin University (Earth Science Edition) | Year: 2013

In order to simulate continuous conductivity of subsurface medium and inverse continuous medium, we worked on the finite element forward modeling on line source of FCSEM (frequency domain controlled-source electromagnetic) for two-dimensional block linear change of conductivity. In each unit, the linear interpolation both for electrical field and conductivity parameter was used, which would keep conductivity changing continuously between each unit. Firstly, boundary value problem and variational problem were given for finite element simulation. And the meshing, interpolation, unit analysis and total synthesis of FEM (finite element method) were discussed in detail. Secondly, sparse storage and BICGSTAB algorithm based on incomplete LU decomposition were used to solve complex equations, which had saved memory and improved compute speed. Then, a homogenous half space model was simulated and its result showed that the FEM numerical solutions of low and high frequency agreed with analytic solutions very well, which proved the correctness of this algorithm. Finally, a horizontal layered model and a vertical fault model were calculated, the contour maps both for apparent resistivity and phase reflected anomaly quite well. All of these had showed this algorithm can simulate the line source of FCSEM for continuous conductivity effectively.

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