The paper is written to analyze the behavior of a selected set of vehicles with different makes, on how they survive after each owner change. The data come from Github. The four cars are Honda Accord, Mini Cooper, Che...The paper is written to analyze the behavior of a selected set of vehicles with different makes, on how they survive after each owner change. The data come from Github. The four cars are Honda Accord, Mini Cooper, Chevy Cavalier, and Toyota Avalon. The two faults are Engine System and Transmission System. The data are from 1996 to 2012. The paper used the Kaplan-Meier curve to survival analysis;the paper also calculates and discusses the self-comparison of each car’s four time periods, the four-stage failure rate through median comparison, and the median comparison of fault conditions in all years. We find that all the vehicle types have gotten better with the years and Toyota vehicles are more reliable than Honda.展开更多
From the recent thirty years, scientists will never stop exploring the outer space. To assist the development of travelling into the universe, I devote myself into providing theoretical support and future indications ...From the recent thirty years, scientists will never stop exploring the outer space. To assist the development of travelling into the universe, I devote myself into providing theoretical support and future indications for designing the optimal orbit for satellite to travel in a Three-Body System. This paper offers the optimal orbit for satellite to change path in the earth-moon system. Also, it provides the path for the satellite to use the least fuel to go to the L4 and L5 Lagrange points. These inspiring results are obtained through several steps: to solve the problems caused by the non-linear character of Three-Body System, I use Koopman eigenfunction to change the system into a linear one. Data-driven method is adopted to find the most suitable Koopman eigenfunction to apply control. The traditional LQR operator for linear system is used to design the optimal orbit for the satellite.展开更多
In this study, we research about comb-drive micro-structure, which is a MEMS device used to measure velocities and accelerations. To ensure the accuracy and visualization of the result, we simulate the dynamics of the...In this study, we research about comb-drive micro-structure, which is a MEMS device used to measure velocities and accelerations. To ensure the accuracy and visualization of the result, we simulate the dynamics of the comb drive?using COMSOL Multiphysics, meanwhile introducing the concept of re-meshing.?We aim to find the optimal comb-drive-building material, which can provide the device with the most desirable first eigenfrequency. According to the optimization process, silver is the most suitable construction material. Afterwards, the electric responses of both the optimized device and the pre-optimized one are analyzed in frequency domain and stationary study. We conclude that the capacitance change is positively related to frequency in a linear manner, and that the optimized device has a larger increment of both displacement and capacitance per unit of frequency change than the pre-optimized one, showing that the optimization of material realizes our goal of enhancing electrical performance.展开更多
Percolation theory deals with the numbers and properties of the clusters formed in the different occupation probability. In this Paper, we study the calculation method of small clusters. We calcu-lated the small clust...Percolation theory deals with the numbers and properties of the clusters formed in the different occupation probability. In this Paper, we study the calculation method of small clusters. We calcu-lated the small cluster density of 1, 2 and 3 in the percolation model with the exact method and the numerical method. The results of the two methods are very close, which can be verified by each other. We find that the cluster density of all three kinds of small clusters reaches the highest value when the occupation probability is between 0.1 and 0.2. It is very difficult to get the analytical formula for the exact method when the cluster area is relatively large (such as the area is more than 50), so we can get the density value of the cluster by numerical method. We find that the time required calculating the cluster density is proportional to the percolation area, which is indepen-dent of the cluster size and the occupation probability.展开更多
文摘The paper is written to analyze the behavior of a selected set of vehicles with different makes, on how they survive after each owner change. The data come from Github. The four cars are Honda Accord, Mini Cooper, Chevy Cavalier, and Toyota Avalon. The two faults are Engine System and Transmission System. The data are from 1996 to 2012. The paper used the Kaplan-Meier curve to survival analysis;the paper also calculates and discusses the self-comparison of each car’s four time periods, the four-stage failure rate through median comparison, and the median comparison of fault conditions in all years. We find that all the vehicle types have gotten better with the years and Toyota vehicles are more reliable than Honda.
文摘From the recent thirty years, scientists will never stop exploring the outer space. To assist the development of travelling into the universe, I devote myself into providing theoretical support and future indications for designing the optimal orbit for satellite to travel in a Three-Body System. This paper offers the optimal orbit for satellite to change path in the earth-moon system. Also, it provides the path for the satellite to use the least fuel to go to the L4 and L5 Lagrange points. These inspiring results are obtained through several steps: to solve the problems caused by the non-linear character of Three-Body System, I use Koopman eigenfunction to change the system into a linear one. Data-driven method is adopted to find the most suitable Koopman eigenfunction to apply control. The traditional LQR operator for linear system is used to design the optimal orbit for the satellite.
文摘In this study, we research about comb-drive micro-structure, which is a MEMS device used to measure velocities and accelerations. To ensure the accuracy and visualization of the result, we simulate the dynamics of the comb drive?using COMSOL Multiphysics, meanwhile introducing the concept of re-meshing.?We aim to find the optimal comb-drive-building material, which can provide the device with the most desirable first eigenfrequency. According to the optimization process, silver is the most suitable construction material. Afterwards, the electric responses of both the optimized device and the pre-optimized one are analyzed in frequency domain and stationary study. We conclude that the capacitance change is positively related to frequency in a linear manner, and that the optimized device has a larger increment of both displacement and capacitance per unit of frequency change than the pre-optimized one, showing that the optimization of material realizes our goal of enhancing electrical performance.
文摘Percolation theory deals with the numbers and properties of the clusters formed in the different occupation probability. In this Paper, we study the calculation method of small clusters. We calcu-lated the small cluster density of 1, 2 and 3 in the percolation model with the exact method and the numerical method. The results of the two methods are very close, which can be verified by each other. We find that the cluster density of all three kinds of small clusters reaches the highest value when the occupation probability is between 0.1 and 0.2. It is very difficult to get the analytical formula for the exact method when the cluster area is relatively large (such as the area is more than 50), so we can get the density value of the cluster by numerical method. We find that the time required calculating the cluster density is proportional to the percolation area, which is indepen-dent of the cluster size and the occupation probability.
