Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2022-06-06 Cooperative journals: 《计算机应用研究》
Abstract： Aiming at the problem that it is difficult to take into account both obstacle avoidance and formation when multi-AUV system plans path in unknown environment, this paper proposed a multi-AUV cooperative obstacle avoidance method based on leader-follower and behavior. First, this paper designed a local path planning method for AUV by constructing the evaluation function of collision risk and deviation from the target; on this basis, combined with formation control method, this paper designed different behaviors and behavior selection patterns for leader and followers respectively. The semi-physical simulation experiment results show that the algorithm can realize the cooperative obstacle avoidance of multi-AUV system in unknown environment, and the formation deviation and recovery time are better than traditional multi-robot obstacle avoidance algorithms. Experimental results verify the feasibility and effectiveness of the algorithm.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-07-09 Cooperative journals: 《计算机应用研究》
Abstract： As the bearing fault signal is non-stationary and non-linear in nature, this paper used the wavelet packet decomposition (WPD) and auto-regressive (AR) spectrum estimating method to extract features. In order to improve the accuracy of diagnosis, the deep believe network was proposed to train diagnostic models. Firstly, using the WPD and AR spectrum estimating method to calculate the energy of different signal bands to realize the feature extraction of vibration signals. Then, using the extracted eigenvalues as input vectors of the deep belief network to conduct model training. Finally, using the trained model to carry out bearing fault diagnosis. In order to verify the effectiveness of the proposed method, using the rotating bearing data set provided by the Case Western Reserve University in the United States, the algorithm is compared with three fault diagnosis methods. Experimental results show that the proposed method has better diagnostic performance.
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-05-20 Cooperative journals: 《计算机应用研究》
Abstract： The lightweight block ciphers can be widely used in various applications, such as smart cities, internet of things and cloud computation and so on, in order to protect data and information secure. Midori is a lightweight block cipher proposed in ASIACRYPT 2015. Its block size has two scenarios, i. e, 64 bits and 128 bit, denoted by Midori64 and Midori128 respectively. Up to now, there are no results about meet-in-the-middle attacks on Midori128. This paper developed a meet-in-the-middle attack on 10-round Midori128 for the first time. Specifically, studying the basic construction and key schedule of Midori128, this paper constructed a 7-round distinguisher on Midori128 by using the differential enumeration and key-dependent sieve techniques. Through appending one round at its top and two rounds at its bottom, this paper mounted a meet-in-the-middle attack on 10-round Midori128. In the attack, time-memory tradeoff technique and some weak subkeys were considered so as to reduce the time complexity of online phase. Finally, the data, time and memory complexities of our attack are 2125 chosen plaintexts, 2126.5 10-round encryptions and 2105 128-bit blocks, respectively.
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