Papers by Keyword: Inversion

Abstract: We established a typical ripped-rock revetment engineering geoelectric model based the resistivity difference of ripped-rock and its surrounding rock. And we also realized the models’ forward and inversion calculation for different device types of high density resistivity method using finite element method. Results show that the α device could delineate the horizontal scope of the ripped-rock better, and the γ device could reflect the bottom of ripped-rock better than the other three device. In addition, we can also get riprap’s bottom boundary according to the gradient belt of resistivity of the β device. In a real world application, we use the small subdomain filtering technology to enhance the image, better divide the riprap distribution range.

Abstract: In order to improve the resolution and accuracy of the inversion, this paper proposed a new inversion method. By introducing constraint sparse spike inversion, the new method can fully take the advantages of high vertical resolution of logging data and the preferable transverse continuity of the seismic data to improve the resolution of the profiles and the quality of imaging and inversion in specific areas. Experimental results showed that this solution can deduce more precise and reasonable inversion result than other inversion solution. Constraint sparse spike inversion can generate reflection coefficients with broad frequency band and solve the marking problems preferably, thereby makes the impedance model obtained from the inversion even close to the actual situation underground.

Abstract: The main function of the application software of the rapid inversion method of 3D apparent physical properties, and the key techniques used to achieve software are described in this paper. The core modules of the software is apparent physical properties inversion which can achieve the 3D apparent density and the 3D apparent magnetic inversion calculation, in addition, the software provides data preprocessing, reduction to the pole, the potential field continuation and potential field cut function. In software implementation process, first, compiling the calculation program modules by Fortran90 language, and then combining with dynamic link library, multi-threading and Surfer automated call technology, we compiled the visualization software interface to realize the function of the new method by C, C + + language, under the C + + Builder6.0 environment.

Abstract: A rapid method for 3D physical properties inversion based on separation and continuation of potential field are introduced in this paper. The inversion technique characterized by faster computing speed, it does not need to divide the underground field sources region into many rectangular blocks in one time and does not need to solve linear algebraic equations as well. So, this technique can overcome the requirement of large computer memory, unstable solution and computation time bottleneck which hinders the application of 3D inversion to practice. The method is used to apparent magnetic susceptibility inversion of magnetic anomaly in a iron mine area, the inversion results show that the method has good accuracy, and the advantages of strong stability and a high computation speed, and is suitable for 3D inversion of magnetic data in large area.

Abstract: Identification of a bird constitutive model and its parameters is a very difficult work in bird-impact coupling solution. In order to identify the constitutive model and the parameters simultaneously, an inversion analytic model for the bird material parameters is given based on penalty function method and nonlinear optimization principle, and then combining the model preferential criterion proposed in this paper, the identification system of the bird constitutive model is established with ANSYS Parametric Design Language (APDL). Finally, the feasibility and practicability of this identification method are verified by an example.

Abstract: A new multi-parameter optimal inversion method for jet ratio and jet angle is established by coupling data-driven model theory with variable density anisotropic turbulent buoyant jet model in this paper. In this method, firstly the multi-parameter matching cases of jet ratio and jet angle are computed by the jet model, and the solution space of internal observation site in the computation waters is constructed by numerical simulation results. Secondly, the nonlinear relationship between state variables (dilution degree) and control variables (model multi-parameter) is established by data-driven model theory. Finally the optimal solution is obtained by inputting the needed dilution degree to the relationship. The numerical results show that multi-parameter optimal coupled inversion method is efficient for the optimal jet parameters and has advantages of jet water mixing with environment water.

Abstract: To fulfill the requirements of processing, analysis and inversing the observational data of experimentations, simulation software for the inversion of satellite experimentations is designed and developed independently on the developing platform of Qt, based on satellite observational data inverse theory. It provides a simulation and calculation platform for analysis and evaluation of space tests. By using dynamics principle and energy conservation principle, the software resolves inverse problems in satellite orbital dynamics. This article mainly presents the function and design method of the software, explains the design goals, shows the overall design framework, and emphasizes key technologies and countermeasures in process of the software design and realization. The software could be used to investigate the inversion of observational data and evaluate technologic indexes in satellite tests.

Abstract: A MMW radiometer is widely used in remote sensing and guidance. In order to obtain the real brightness temperature distribution of the target, we need to solve the first kind of ill Fredholm integral equation of radiometric antenna temperature. The paper presents a kind of inversion method for modifying antenna pattern and the approach of error compensation. Compared with the theoretical calculation model of 3mm smooth water surface, the results show this algorithm has a higher accuracy for the measurement application.

Abstract: CoCr_xFe_2-xO₄ samples with x = 0.0 to 2.0 were prepared by air oxidation of aqueous suspension containing Co²⁺, Cr³⁺ and Fe³⁺ ions and characterized by x-ray diffraction. Positron lifetime and coincidence Doppler broadening (CDB) measurements indicated three distinct stages of positron trapping in defects. Initially the vacancy-type defects located at the A-sites (tetrahedral) trapped positrons but, with the substitution of Fe by Cr in low concentrations (x <= 0.7), positrons are trapped by defects at the B-sites (octahedral). Mossbauer spectroscopic results indicated the cationic distribution at B-sites to be stoichiometry-dependent and, till x = 0.7, the deficiency of Fe³⁺(B) ions was compensated by interchange of Fe³⁺(A) ions with Co²⁺(B) ions. Between x = 0.9 and 1.7, the substitution resulted in continued decrease of Fe³⁺(B) ions and the structure got fully transformed into a normal spinel configuration during x = 1.8 to 2.0.

Abstract: We report in this work about the inversion of the spinel structure of ZnFe₂O₄ induced by the substitution of Zn²⁺ by Ni²⁺ ions. Positron lifetimes were measured in Zn_1-xNi_xFe₂O₄ with different concentrations (x) of doped Ni²⁺ ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni²⁺ is smaller in size than Zn²⁺, defects due to non-stoichiometry are less in NiFe₂O₄ than in ZnFe₂O₄. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.