查看更多>>摘要：Diabetic retinopathy (DR) is one of the most important causes of visual impairment.Automatic recognition of DR lesions,like hard exudates (EXs),in retinal images can contribute to the diagnosis and screening of the disease.To achieve this goal,an automatically detecting approach based on improved FCM (IFCM) as well as support vector machines (SVM) was established and studied.Firstly,color fundus images were segmented by IFCM,and candidate regions of EXs were obtained.Then,the SVM classifier is confirmed with the optimal subset of features and judgments of these candidate regions,as a result hard exudates are detected from fundus images.Our database was composed of 126 images with variable color,brightness,and quality.70 of them were used to train the SVM and the remaining 56 to assess the performance of the method.Using a lesion based criterion,we achieved a mean sensitivity of 94.65％ and a mean positive predictive value of 97.25％.With an image-based criterion,our approach reached a 100％ mean sensitivity,96.43％ mean specificity and 98.21％ mean accuracy.Furthermore,the average time cost in processing an image is 4.56 s.The results suggest that the proposed method can efficiently detect EXs from color fundus images and it could be a diagnostic aid for ophthalmologists in the screening for DR.
查看更多>>摘要：Biogas from renewable sources and natural gas (NG) are both high-efficient and good-quality gaseous fuels on account of their enrichment in methane.Due to the dissimilar physical properties of biogas and NG,biogas cannot substitute NG directly without treatment and is usually used on site due to the high cost of the transportation and distribution via exclusive pipeline system.Consequently,the injection of biogas into existing NG infrastructure was proposed to address the deficiency.In this paper,the Wobbe index (WI) as well as the combustion potential (CP) were introduced for analyzing the interchangeability of an NG-biogas mixture,and a mathematical framework was put forward for modeling and simulating NG grid with a decentralized biogas injection.Results show that the maximum admissible amount of biogas in mixture was 10.5％ by volume.A medium pressure network was used to interrogate the comprehensive effect of distributed biogas injection,which showed an impact on both gas quality and hydraulic regime across the grid.
查看更多>>摘要：Product storage policy,single picking volume and picking routing are the three factors of vital importance that affect the efficiency of a crane to pick goods in automated storage and retrieval systems (AS/RS).Comparative experiments on picking efficiency were conducted targeting picking operation with order of 1 to 20.Based on dedicated and random storage policies,4 picking methods of patching-based,S-type,return-type and optimized-type routes were used and compared in the experiments.The results show that either the dedicated policy or the random policy was applied,crane worked most efficiently with optimizedtype route,followed by S-type path,patching-based path,and return-type path.When the number of orders in a single picking is larger (more than 5),the random storage policy is preferable to the dedicated policy.
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NSTL
万方数据
维普