According to the characteristics of strong coupling and nonlinearity of the robot arm control system, a fuzzy PID controller optimized by the genetic algorithm (GA) is proposed. The method realizes ...the control of nonlinear system and improves the dynamic response speed and adaptive capacity of the system by the fuzzy control strategy. Taking the overall performance index as the fitness function, the genetic algorithm is used to optimize and self-tune the PID control parameters to meet the design requirements of system which can make up the shortage of low precision of fuzzy control. In the control of robot arm, the fuzzy PID control based on parameter optimization by the genetic algorithm has the characteristics of fast response and small overshoot. In the presence of external disturbances and parameter variation of the object, system has a certain ability to adapt. Simulation results show that the algorithm is effective and practical, and can be used in other control objects and processes.
Password guessing plays an important role in studying the vulnerability of passwords to improve security. In modern password guessing methods, the patterns of passwords from users in specific regions ...are discovered from a large number of leaked passwords. Most traditional methods, such as PCFG, Markov process, and other deep learning methods rely only on the training set. Different from other application areas of machine learning, the training set of password guessing comes from leaked real password sets, such as Rockyou, CSDN, and VK. Traditional approaches of password guessing are effective for large-scale training sets. However, the size of leaked password sets leaked by users of small languages or users of specific organizations is very small, which makes it difficult for current password guessing methods which relying only on training sets to discover enough words in passwords. In order to solve this problem, this paper proposed a corpus-based password guessing method. First, we analyzed the common words and their categories in the leaked password sets from users in three different countries. On this basis, we proposed an organization method for multiple language corpora, and constructed corpora of more than 3 million words. Secondly, we improved the traditional PCFG password segmentation method and described password structure based on corpora. Third, we evaluated the probability of words in the corpora which are not appearing in the training set based on the Lapalace smoothing. Actual tests show that our method can produce a finer structure than the PCFG. When the size of the training set decreases, the cracking rate of the PCFG decreases significantly, while the impact of our method is not significant, and the cracking rate is significantly higher than that of the PCFG.
This paper gives new formulae of X-ray dynamical diffraction for a plane-parallel crystal with finite thickness. These formulae are applicable when the ratio of the two absolute values, i.e. the real ...part of the atomic scattering factor and the imaginary part, is arbitrary. Based on these formulae, the results calculated in both the Bragg and the Laue cases show that the formulae not only agree well with originally theoretical predictions, but also provide an incentive for cases which have not been studied.
