This paper uses two navigation schemes to prove the potential of a novel autonomous orbit determination with stellar horizon atmospheric refraction measurements. Scheme one needs a single processor and uses an extende...This paper uses two navigation schemes to prove the potential of a novel autonomous orbit determination with stellar horizon atmospheric refraction measurements. Scheme one needs a single processor and uses an extended Kalman filter. The second scheme needs two parallel processors. One processor uses a hatched leastsquare initial state estimator and a high-precision dynamic state propagator. The other processor uses a real-time orbit predictor. Simulations have been executed respectively for three types （low/medial/high） of satellite orbits on which various numbers of stars are observed. The results show both schemes can autonomously determine the orbits with a considerable performance. The second scheme in general performs a little better than the first scheme.展开更多
Discovering and preventing the frauds which affect the business organizations negatively require a greater degree of specialism. Detecting a fraud in the organizations is very hard, because not only such a fraud is ex...Discovering and preventing the frauds which affect the business organizations negatively require a greater degree of specialism. Detecting a fraud in the organizations is very hard, because not only such a fraud is exercised by the people who have deep professional knowledge, but they also use some peculiar methods to hide their tricky activities. Therefore, it is obvious that it is necessary to have the fraud examiners and especially fraud auditors who should have deep professional knowledge and experience. The aim of this study is to give some general information about employee fraud, which targets the different functions of the companies, takes many forms, and reaches important levels in recent years, in qualitative point. In this study, firstly, forensic accounting is a highly dynamic area in nowadays which is related to fraud auditing and its profession, and its search area of frauds and employee frauds subjects have been reviewed. Finally, qualitative data were collected about fraud incidents which had occurred and been sent to the court in the province of Kars in Turkey. Actual case analysis method has been used in this study. The obtained data have been analyzed by using Statistical Package for the Social Sciences （SPSS） 17 statistics package program. Results of the study have been discussed and interpreted in details.展开更多
The objective of the whole-spacecraft vibration isolation (WSVI) system is to reduce the launch-induced dynamic loads and the quality control cost of the satellite and its components, and to increase the launch reliab...The objective of the whole-spacecraft vibration isolation (WSVI) system is to reduce the launch-induced dynamic loads and the quality control cost of the satellite and its components, and to increase the launch reliability by insertion of isolators between the satellite and the launch vehicle. A niche hybrid genetic algorithm (NHGA) is proposed to optimize stiffness and damping of the isolators. Through the comparison of the frequency response analysis results, it shows that the optimized WSVI system more effectively reduces spacecraft axial / lateral response due to the broadband structure-born launch environment. At the same time, the case of the whole-spacecraft vibration isolation optimization design demonstrates the efficiency and validity of the genetic algorithm.展开更多
In this paper,we propose a roll angle measurement method with a large range based on the photoelectronic autocollimator.According to the corresponding relationship between the rotation position of the measured shaft a...In this paper,we propose a roll angle measurement method with a large range based on the photoelectronic autocollimator.According to the corresponding relationship between the rotation position of the measured shaft and the spot position on the circular trajectory,the roll angle is calculated quickly and conveniently using a simple algorithm.Only a mirror,a coupler and a fine shaft are contained in the measurement system besides the photoelectronic autocollimator.Aiming at the terrible measurement error induced by the axis wobbly error,two measurement schemes are proposed,which are linking the fine precision shaft to the measured shaft for reducing the axis wobbly error and using the segment measurement to enlarge the radius of the circular trajectory.The experimental results show that the measurement error is decreased by ±0.38°.The roll angle error of the mechanism is ±0.14°,and the measurement precision is about ±2′.The proposed method can be widely used in the engineering fields.展开更多
文摘This paper uses two navigation schemes to prove the potential of a novel autonomous orbit determination with stellar horizon atmospheric refraction measurements. Scheme one needs a single processor and uses an extended Kalman filter. The second scheme needs two parallel processors. One processor uses a hatched leastsquare initial state estimator and a high-precision dynamic state propagator. The other processor uses a real-time orbit predictor. Simulations have been executed respectively for three types （low/medial/high） of satellite orbits on which various numbers of stars are observed. The results show both schemes can autonomously determine the orbits with a considerable performance. The second scheme in general performs a little better than the first scheme.
文摘Discovering and preventing the frauds which affect the business organizations negatively require a greater degree of specialism. Detecting a fraud in the organizations is very hard, because not only such a fraud is exercised by the people who have deep professional knowledge, but they also use some peculiar methods to hide their tricky activities. Therefore, it is obvious that it is necessary to have the fraud examiners and especially fraud auditors who should have deep professional knowledge and experience. The aim of this study is to give some general information about employee fraud, which targets the different functions of the companies, takes many forms, and reaches important levels in recent years, in qualitative point. In this study, firstly, forensic accounting is a highly dynamic area in nowadays which is related to fraud auditing and its profession, and its search area of frauds and employee frauds subjects have been reviewed. Finally, qualitative data were collected about fraud incidents which had occurred and been sent to the court in the province of Kars in Turkey. Actual case analysis method has been used in this study. The obtained data have been analyzed by using Statistical Package for the Social Sciences （SPSS） 17 statistics package program. Results of the study have been discussed and interpreted in details.
基金The Natural Science Foundation of China(No. 60402003)The National High Technology and Development Program of China(No. 2002AA745120)
文摘The objective of the whole-spacecraft vibration isolation (WSVI) system is to reduce the launch-induced dynamic loads and the quality control cost of the satellite and its components, and to increase the launch reliability by insertion of isolators between the satellite and the launch vehicle. A niche hybrid genetic algorithm (NHGA) is proposed to optimize stiffness and damping of the isolators. Through the comparison of the frequency response analysis results, it shows that the optimized WSVI system more effectively reduces spacecraft axial / lateral response due to the broadband structure-born launch environment. At the same time, the case of the whole-spacecraft vibration isolation optimization design demonstrates the efficiency and validity of the genetic algorithm.
基金supported by the National Natural Science Foundation of China(Nos.111742741117427961205021 and 11204299)
文摘In this paper,we propose a roll angle measurement method with a large range based on the photoelectronic autocollimator.According to the corresponding relationship between the rotation position of the measured shaft and the spot position on the circular trajectory,the roll angle is calculated quickly and conveniently using a simple algorithm.Only a mirror,a coupler and a fine shaft are contained in the measurement system besides the photoelectronic autocollimator.Aiming at the terrible measurement error induced by the axis wobbly error,two measurement schemes are proposed,which are linking the fine precision shaft to the measured shaft for reducing the axis wobbly error and using the segment measurement to enlarge the radius of the circular trajectory.The experimental results show that the measurement error is decreased by ±0.38°.The roll angle error of the mechanism is ±0.14°,and the measurement precision is about ±2′.The proposed method can be widely used in the engineering fields.
