According to the current research status of component retrieval, the component description model based on facet classification is improved by adding semantic features. Furthermore, the component retrieval process mode...According to the current research status of component retrieval, the component description model based on facet classification is improved by adding semantic features. Furthermore, the component retrieval process model is put forward by combining the domain ontology with the relative concept match algorithm. A detailed illustration of a component reasoning engine and a component classification engine is given and the component classification algorithm is provided by using the Naive Bayes algorithm based on domain ontology. The experimental results show that the recall ratio and the precision ratio are obviously improved by using the method based on semantics, and demonstrate the feasibility and effectiveness of the proposed method.展开更多
The purpose of this paper is to investigate the performance improvement mechanism of a high power vertical centrifugal pump by using numerical calculations.Therefore,a comparative study of energy losses and internal f...The purpose of this paper is to investigate the performance improvement mechanism of a high power vertical centrifugal pump by using numerical calculations.Therefore,a comparative study of energy losses and internal flow characteristics in the original and optimized models was carried out with special attention to the hydraulic component matching.The optimized model(model B)was obtained by optimizing the vaned diffuser and volute based on the original model(model A),mainly the diffuser inlet diameter,diffuser inlet vane angle,volute channel inlet width and volute throat area were changed.Firstly,the comparative results on performance and energy losses of two models showed that the efficiency and head of model B was significantly increased under design and part-load conditions.It is mainly due to the dramatic reduction of energy loss PL in the diffuser and volute.Then,the comparisons of PL and flow patterns in the vaned diffuser showed that the matching optimization between the model B impeller outlet flow angle and diffuser inlet vane angle resulted in a better flow pattern in both the circumferential and axial directions of the diffuser,which leads to the PL3 reduction.The meridian velocity Vm of model B was significantly increased at diffuser inlet regions and resulted in improvements of flow patterns at diffuser middle and outlet regions as well as pressure expansion capacity.Finally,the comparisons of PL and flow characteristics in the volute showed that the turbulence loss reduction in the model B volute was due to the flow pattern improvement at diffuser outlet regions which provided better flow conditions at volute inlet regions.The matching optimization between the diffuser and volute significantly reduced the turbulence loss in volute sections 1–4 and enhanced the pressure expansion capacity in sections 8–10.展开更多
基金The National Natural Science Foundation of China(No60072006)
文摘According to the current research status of component retrieval, the component description model based on facet classification is improved by adding semantic features. Furthermore, the component retrieval process model is put forward by combining the domain ontology with the relative concept match algorithm. A detailed illustration of a component reasoning engine and a component classification engine is given and the component classification algorithm is provided by using the Naive Bayes algorithm based on domain ontology. The experimental results show that the recall ratio and the precision ratio are obviously improved by using the method based on semantics, and demonstrate the feasibility and effectiveness of the proposed method.
基金Project supported by the National Natural Science Foundation of China(Grant No.51979125)supported by the Jiangsu Provincial Science Fund for Distinguished Young Scholars(Grant No.BK20211547)+2 种基金the Technological Innovation Team Project in Colleges and Universities of Jiangsu Province(Grant No.SKJ(2021)-1)the Open Research Subject of Key Laboratory of Fluid Machinery and Engineering(Xihua University)of Sichuan Province(Grant No.LTDL-2022007)the Graduate Research and Innovation Projects of Jiangsu Province(Grant No.KYCX23_3701).
文摘The purpose of this paper is to investigate the performance improvement mechanism of a high power vertical centrifugal pump by using numerical calculations.Therefore,a comparative study of energy losses and internal flow characteristics in the original and optimized models was carried out with special attention to the hydraulic component matching.The optimized model(model B)was obtained by optimizing the vaned diffuser and volute based on the original model(model A),mainly the diffuser inlet diameter,diffuser inlet vane angle,volute channel inlet width and volute throat area were changed.Firstly,the comparative results on performance and energy losses of two models showed that the efficiency and head of model B was significantly increased under design and part-load conditions.It is mainly due to the dramatic reduction of energy loss PL in the diffuser and volute.Then,the comparisons of PL and flow patterns in the vaned diffuser showed that the matching optimization between the model B impeller outlet flow angle and diffuser inlet vane angle resulted in a better flow pattern in both the circumferential and axial directions of the diffuser,which leads to the PL3 reduction.The meridian velocity Vm of model B was significantly increased at diffuser inlet regions and resulted in improvements of flow patterns at diffuser middle and outlet regions as well as pressure expansion capacity.Finally,the comparisons of PL and flow characteristics in the volute showed that the turbulence loss reduction in the model B volute was due to the flow pattern improvement at diffuser outlet regions which provided better flow conditions at volute inlet regions.The matching optimization between the diffuser and volute significantly reduced the turbulence loss in volute sections 1–4 and enhanced the pressure expansion capacity in sections 8–10.