Content-based image retrieval has been an active area of research for more than ten years. Gabor schemes and support vector machine （SVM） method have been proven effective in image representation and clas-sification...Content-based image retrieval has been an active area of research for more than ten years. Gabor schemes and support vector machine （SVM） method have been proven effective in image representation and clas-sification. In this paper, we propose a retrieval scheme based on Gabor filters and SVMs for hepatic computed tomography （CT） images query. In our experiments, a batch of hepatic CT images containing several types of CT findings are used for the retrieval test. Precision comparison between our scheme and existing methods is presented.展开更多
To further improve the steady-state performance of the conventional dual vector model predictive current control(MPCC),an improved optimal duty MPCC strategy for permanent magnet synchronous motor(PMSM)is proposed.Thi...To further improve the steady-state performance of the conventional dual vector model predictive current control(MPCC),an improved optimal duty MPCC strategy for permanent magnet synchronous motor(PMSM)is proposed.This strategy is realized by selecting an optimal voltage vector combination and its duration from the five basic voltage vector combinations,followed by acting on the inverter.The five combinations are:the combination of the optimal voltage vector at the previous moment and basic voltage vector with an angle difference of 60°;the combination of the optimal voltage vector at the previous moment and basic voltage vector with an angle difference of-60°;the combination of the aforementioned three basic voltage vectors with the zero vector.Experimental results indicate that the method effectively reduces the stator current ripple without increasing the calculational burden.Furthermore,it improves the steady-state performance of the system without altering the dynamic performance of the system.展开更多
String similarity join(SSJ) is essential for many applications where near-duplicate objects need to be found. This paper targets SSJ with edit distance constraints. The existing algorithms usually adopt the filter-and...String similarity join(SSJ) is essential for many applications where near-duplicate objects need to be found. This paper targets SSJ with edit distance constraints. The existing algorithms usually adopt the filter-andrefine framework. They cannot catch the dissimilarity between string subsets, and do not fully exploit the statistics such as the frequencies of characters. We investigate to develop a partition-based algorithm by using such statistics.The frequency vectors are used to partition datasets into data chunks with dissimilarity between them being caught easily. A novel algorithm is designed to accelerate SSJ via the partitioned data. A new filter is proposed to leverage the statistics to avoid computing edit distances for a noticeable proportion of candidate pairs which survive the existing filters. Our algorithm outperforms alternative methods notably on real datasets.展开更多
基金the Joint National Natural Science Foundation of China under Grant No.30770589.
文摘Content-based image retrieval has been an active area of research for more than ten years. Gabor schemes and support vector machine （SVM） method have been proven effective in image representation and clas-sification. In this paper, we propose a retrieval scheme based on Gabor filters and SVMs for hepatic computed tomography （CT） images query. In our experiments, a batch of hepatic CT images containing several types of CT findings are used for the retrieval test. Precision comparison between our scheme and existing methods is presented.
基金Supported by the National Natural Science Foundation of China(51907061)Natural Science Foundation of Hunan Province(2019JJ50119)National Engineering Laboratory of UHV Engineering Technology(Kunming,Guangzhou)(NEL202008)。
文摘To further improve the steady-state performance of the conventional dual vector model predictive current control(MPCC),an improved optimal duty MPCC strategy for permanent magnet synchronous motor(PMSM)is proposed.This strategy is realized by selecting an optimal voltage vector combination and its duration from the five basic voltage vector combinations,followed by acting on the inverter.The five combinations are:the combination of the optimal voltage vector at the previous moment and basic voltage vector with an angle difference of 60°;the combination of the optimal voltage vector at the previous moment and basic voltage vector with an angle difference of-60°;the combination of the aforementioned three basic voltage vectors with the zero vector.Experimental results indicate that the method effectively reduces the stator current ripple without increasing the calculational burden.Furthermore,it improves the steady-state performance of the system without altering the dynamic performance of the system.
文摘String similarity join(SSJ) is essential for many applications where near-duplicate objects need to be found. This paper targets SSJ with edit distance constraints. The existing algorithms usually adopt the filter-andrefine framework. They cannot catch the dissimilarity between string subsets, and do not fully exploit the statistics such as the frequencies of characters. We investigate to develop a partition-based algorithm by using such statistics.The frequency vectors are used to partition datasets into data chunks with dissimilarity between them being caught easily. A novel algorithm is designed to accelerate SSJ via the partitioned data. A new filter is proposed to leverage the statistics to avoid computing edit distances for a noticeable proportion of candidate pairs which survive the existing filters. Our algorithm outperforms alternative methods notably on real datasets.
