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- 实验方案
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An optimized space-time Gaussian beam migration method with dynamic parameter control
摘要： In the Gaussian beam (GB) method, initial beam parameters are principal factors influencing the accuracy and computational efficiency of seismic depth imaging. Various optimized beam parameter strategies for Gaussian beam migration (GBM) have been proposed to improve imaging quality as well as computational efficiency, while optimized space-time Gaussian beam schemes for seismic migration have still not been fully investigated. In this paper, an optimized space-time Gaussian beam approach with dynamic parameter control for seismic depth imaging is developed. We first provide an expression for dynamic beam parameter by taking in account the effect of velocity field variation on the beam forming. Based on dynamic beam parameters, the new space-time adaptive Gaussian beam generated by an arbitrary source wavelet is obtained, which can adaptively calculate the beam width to make the seismic beam energy better focused in the central ray neighborhood. Then, the forward wavefield is constructed in two-dimensional (2D) acoustic media by space-time adaptive Gaussian beam for the implementation of migration. Adhering to the framework of conventional space-time Gaussian beam method, we perform the up-going ray tracing from subsurface imaging points to the receiver surface to compute the asymptotic Green function for the construction of the backward wavefield. Numerical experiments demonstrate that the new presented approach has a superior accuracy for seismic depth imaging in both shallow and deep regions compared to the conventional space-time Gaussian beam migration scheme.
关键词： Space-time Gaussian beam,Green function,Up-going ray tracing,Dynamic beam parameter
更新于2025-09-23 15:21:21
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Successive DSPE-based coherently distributed sources parameters estimation for unmanned aerial vehicle equipped with antennas array
摘要： In electronic countermeasures and reconnaissance, unmanned aerial vehicle (UAV) has played a more and more significant role. Usually when UAV conducts low altitude reconnaissance, due to the complicated environment, the reflected signals of the same source through different propagation paths will produce multipath signals. In this paper, we construct the received multipath signals of UAV with antennas array as coherently distributed (CD) sources model and propose a successive distributed signal parameter estimation (S-DSPE) algorithm to estimate its nominal direction of arrival (DOA) and angular spread. The proposed algorithm simplifies two-dimensional (2D) spectral peak searching within the conventional DSPE algorithm to one-dimensional spectral peak searching, which remarkably reduces the computational complexity of conventional DSPE algorithm. Furthermore, the parameters estimation performance of the proposed algorithm is close to the conventional DSPE algorithm, and outperforms the estimation of signal parameters via rotational invariance technique (ESPIRT) algorithm and propagator method(PM). The simulations results verify the usefulness of the proposed algorithm.
关键词： Distributed signal parameter estimation (DSPE),Nominal direction of arrival (DOA),Coherently distributed(CD),Unmanned aerial vehicle (UAV)
更新于2025-09-23 15:21:21
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On the root mean square error (RMSE) calculation for parameter estimation of photovoltaic models: A novel exact analytical solution based on Lambert W function
摘要： In the literature, one can find a lot of methods and techniques employed to estimate single diode solar photovoltaic (PV) cell parameters. The efficiency of these methods is usually tested by calculating the Root Mean Square Error (RMSE) between the measured and estimated values of the solar PV cell output current. In this work, first, the values of RMSE calculated using 69 different methods published in many journal papers for the well-known RTC France solar PV cell are presented and discussed. Second, a novel exact analytical solution for RMSE calculation based on the Lambert W function is proposed. The results obtained show that the RMSE values were not calculated correctly in most of the methods presented in the literature since the exact expression of the calculated cell output current was not used. Third, the precision of calculation of the methods used for analytical solving of Lambert W equation is presented and discussed. Fourth, the applicability of the proposed solution methodology in accordance with current-voltage characteristics measured in the laboratory for solar modules of Clean Energy Trainer Setup is checked. Identification of its unknown parameters is presented using three optimization techniques. Further, the proposed solution methodology is proven for Solarex MSX–60 PV module, and the most promising 5-parameter single diode parameters are estimated based on minimization of the precise RMSE values calculated. Finally, this work aimed to develop a good base for proper investigation and implementation of optimization algorithms to solve the parameter estimation problem of 5-parameter single diode PV equivalent circuits.
关键词： Root mean square error,5-parameter single diode model,PV parameter estimation,Optimization,RTC France solar cell,Lambert W function
更新于2025-09-23 15:21:01
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Relativistic Self Focusing and Frequency Shift of super-Gaussian Laser Beam in Plasma
摘要： Relativistic self focusing and frequency shift of laser beam having super-Gaussian profile in space and Gaussian profile in time is studied in a plasma. The relativistic mass nonlinearity is found to cause time dependent self focusing of the laser pulse and the saturation effect of nonlinearity avoids point focusing of the beam. For ultrashort laser pulse, the front of the pulse undergoes frequency down shift while that of the tail undergoes up shift. Frequency shift increases and self focusing becomes stronger for higher intensity of the laser. The self focusing is also stronger for the laser beam carrying larger wavelength.
关键词： Beam width parameter,Self focusing,Frequency shift,super-Gaussian laser,Moment Theory,Relativistic nonlinearity
更新于2025-09-23 15:21:01
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Behavior of Specialty Optical Fibers in Crude Oil Environment
摘要： Models of biochemical reaction networks commonly contain a large number of parameters, while at the same time, there is only a limited amount of (noisy) data available for their estimation. As such, the values of many parameters are not well known as nominal parameter values have to be determined from the open scienti?c literature and a signi?cant number of the values may have been derived in different cell types or organisms than that which is modeled. There clearly is a need to estimate at least some of the parameter values from experimental data; however, the small amount of available data and the large number of parameters commonly found in these types of models require the use of regularization techniques to avoid over?tting. A tutorial of regularization techniques, including parameter set selection, precedes a case study of estimating parameters in a signal transduction network. Cross-validation results rather than ?tting results are presented to further emphasize the need for models that generalize well to new data instead of simply ?tting the current data.
关键词： parameter estimation,Computational systems biology,nonlinear dynamical systems
更新于2025-09-23 15:21:01
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[IEEE 2019 International Council on Technologies of Environmental Protection (ICTEP) - Star?? Smokovec, Slovakia (2019.10.23-2019.10.25)] 2019 International Council on Technologies of Environmental Protection (ICTEP) - The Statistical Measurements of Photovoltaic Panels Degradation
摘要： State-space current control enables high dynamic performance of a three-phase grid-connected converter equipped with an LCL filter. In this paper, observer-based state-space control is designed using direct pole placement in the discrete-time domain and in grid-voltage coordinates. Analytical expressions for the controller and observer gains are derived as functions of the physical system parameters and design specifications. The connection between the physical parameters and the control algorithm enables automatic tuning. Parameter sensitivity of the control method is analyzed. The experimental results show that the resonance of the LCL filter is well damped, and the dynamic performance specified by direct pole placement is obtained for the reference tracking and grid-voltage disturbance rejection.
关键词： parameter sensitivity,Active damping,LCL filter,sensorless state feedback,grid-connected converter,current control
更新于2025-09-23 15:21:01
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Extraction of uncertain parameters of a single-diode model for a photovoltaic panel using lightning attachment procedure optimization
摘要： The aim of this work is to improve the estimation of parameters of solar photovoltaic models. An approach based on lightning attachment procedure optimization, which takes into account the uncertainties of measurements, is proposed. The approach includes three steps: the extraction of the parameters in a conventional manner, the determination of the partial uncertainties of all the parameters, and finally the determination of the instantaneous parameters based on the results of the first two steps. To validate the proposed theoretical developments, the approach is applied to four different photovoltaic parameter estimation problems. The results obtained are compared with those given by well-established algorithms to confirm the effectiveness of the proposed method, revealing that the proposed method exhibits very effective performance with a root-mean-square error on the order of 1 × 10?17, compared with 1 × 10?4 for existing literature methods.
关键词： Lightning attachment procedure optimization,Photovoltaic modeling,Parameter estimation,Uncertain measurements
更新于2025-09-23 15:21:01
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[IEEE 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Brasov, Romania (2019.11.3-2019.11.6)] 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Estimation of Photovoltaic Panel Parameters by a Numerical Heuristic Searching Algorithm
摘要： This work uses the Nelder-Mead approach, which is a direct search optimization method, to obtain the accurate photovoltaic parameters by minimizing a predetermined objective function of five variables. This paper presents some new modifications made to the Nelder-Mead algorithm which allow a better convergence of the method. A comparison study has conducted between this proposed technique and a classical Nelder-Mead algorithm towards the additive noise of the current along with a sensitivity analysis towards the resolution of ADC.
关键词： parameter extraction,Photovoltaic panel,Nelder-Mead algorithm
更新于2025-09-23 15:21:01
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Diagnosis of copper plasma by laser induced breakdown spectroscopy
摘要： In this paper influence of laser energy on the emission spectrum of laser copper-interaction and plasma parameter for plasma Copper by used a first harmonic generated wavelength of Nd:YAG exaction source. The metal plasma that had detection by HR4000 detection system (ocean optics) was use to different excited. plasma temperature via the Boltzmann plot diagram with measuring the electron density number by McWhirter CRITERION. Values of measuring (Ne), (Te) found between (61178776 K°) and (Ne) is (1.77*1015, 2.01*1015 cm-3) at 1064nm.
关键词： LIBS,Copper plasma,electron number density,self-absorption,plasma parameter
更新于2025-09-23 15:21:01
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Porosity and joint property of laser-MIG hybrid welding joints for 304 stainless steel
摘要： Laser-metal inert gas (MIG) hybrid butt welding was carried out on 5 mm-thick 304 stainless steel to study the influence of parameters on porosity defect, weld formation, and property of the joints. Research reveals that laser-MIG hybrid welding of 304 stainless steel has porosity sensitivity. The effects of welding speed and laser power on porosity and formation of welds were analyzed. Results show that increasing of laser power and decreasing of welding speed are conducive to improve the formation of welds and reduce porosity. Improving the welding speed on the premise of ensuring proper weld formation is of considerable significance, which is recommended to be 1.8 m/min. Based on the fixed welding speed, parameter of laser power optimization is carried out. Results show that tensile strength and elongation of the welded joints reach at least 98.1% and 75.8% of the base metal when laser powers are 4.3 and 5.0 kW. Compared with real-time monitoring and the numerical simulation method, this kind of results-oriented optimization parameter method has engineering guiding significance.
关键词： property,welding parameter,weld formation,304 stainless steel,porosity,laser-MIG hybrid weld
更新于2025-09-23 15:21:01