Bundle adjustment is a camera and point refinement technique in a 3D scene reconstruction pipeline. The camera parameters and the 3D points are refined by minimizing the difference between computed projection and obse...Bundle adjustment is a camera and point refinement technique in a 3D scene reconstruction pipeline. The camera parameters and the 3D points are refined by minimizing the difference between computed projection and observed projection of the image points formulated as a non-linear least-square problem. Levenberg-Marquardt method is used to solve the non-linear least-square problem. Solving the non-linear least-square problem is computationally expensive, proportional to the number of cameras, points, and projections. In this paper, we implement the Bundle Adjustment (BA) algorithm and analyze techniques to improve algorithmic performance by reducing the mean square error. We investigate using an additional radial distortion camera parameter in the BA algorithm and demonstrate better convergence of the mean square error. We also demonstrate the use of explicitly computed analytical derivatives. In addition, we implement the BA algorithm on GPUs using the CUDA parallel programming model to reduce the computational time burden of the BA algorithm. CUDA Streams, atomic operations, and cuBLAS library in the CUDA programming model are proposed, implemented, and demonstrated to improve the performance of the BA algorithm. Our implementation has demonstrated better convergence of the BA algorithm and achieved a speedup of up to 16× on the use of the BA algorithm on various datasets.展开更多
The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and...The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and very efficient for reducing harmonic distortion in the output voltage and output current. The proposed nine-level current source inverter has been tested under symmetrical and asymmetrical modes of operation, and their activities are compared using PI and Fuzzy PI (Proportional Integral) controllers with multicarrier PWM (Pulse Width Modulation) strategy. MATLAB/Simulink simulation has been made for the proposed converter to obtain its performance measures. Some experimental results are given to verify the presented Current Source Multilevel Inverter.展开更多
A modified distorted-wave Born approximation （DWBA） method is used to calculate the triple differential cross sections （TDCSs） in a coplanar asymmetric geometry for the electron impact single ionization of a He （...A modified distorted-wave Born approximation （DWBA） method is used to calculate the triple differential cross sections （TDCSs） in a coplanar asymmetric geometry for the electron impact single ionization of a He （ls2） atom at intermediate and lower energies. The post-collision interaction and the polarization effect in （e, 2e） collisions of helium are considered in the calculations. The polarization potentials from the damping method and density functional theory （DFT） are compared. Theoretical results are compared with the recent experimental data.展开更多
文摘Bundle adjustment is a camera and point refinement technique in a 3D scene reconstruction pipeline. The camera parameters and the 3D points are refined by minimizing the difference between computed projection and observed projection of the image points formulated as a non-linear least-square problem. Levenberg-Marquardt method is used to solve the non-linear least-square problem. Solving the non-linear least-square problem is computationally expensive, proportional to the number of cameras, points, and projections. In this paper, we implement the Bundle Adjustment (BA) algorithm and analyze techniques to improve algorithmic performance by reducing the mean square error. We investigate using an additional radial distortion camera parameter in the BA algorithm and demonstrate better convergence of the mean square error. We also demonstrate the use of explicitly computed analytical derivatives. In addition, we implement the BA algorithm on GPUs using the CUDA parallel programming model to reduce the computational time burden of the BA algorithm. CUDA Streams, atomic operations, and cuBLAS library in the CUDA programming model are proposed, implemented, and demonstrated to improve the performance of the BA algorithm. Our implementation has demonstrated better convergence of the BA algorithm and achieved a speedup of up to 16× on the use of the BA algorithm on various datasets.
文摘The paper proposes a Current Source Multilevel Inverter (CSMLI) with single rating inductor topology. Multilevel inverters are most familiar with power converter’s applications due to reduced dv/dt, di/dt stress, and very efficient for reducing harmonic distortion in the output voltage and output current. The proposed nine-level current source inverter has been tested under symmetrical and asymmetrical modes of operation, and their activities are compared using PI and Fuzzy PI (Proportional Integral) controllers with multicarrier PWM (Pulse Width Modulation) strategy. MATLAB/Simulink simulation has been made for the proposed converter to obtain its performance measures. Some experimental results are given to verify the presented Current Source Multilevel Inverter.
文摘A modified distorted-wave Born approximation （DWBA） method is used to calculate the triple differential cross sections （TDCSs） in a coplanar asymmetric geometry for the electron impact single ionization of a He （ls2） atom at intermediate and lower energies. The post-collision interaction and the polarization effect in （e, 2e） collisions of helium are considered in the calculations. The polarization potentials from the damping method and density functional theory （DFT） are compared. Theoretical results are compared with the recent experimental data.
