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【Objective】 Hydraulic loss is a great concern in designing hydraulic apparatus and the objective of this paper is to investigate how to reduce it in the outlet conduit so as to improve the performance of shaft tubular pump. 【Method】 The analysis was based on the standard k-ε turbulent model, and water flow in the conduit was numerically simulated with the simulated results verified against experimental test. The validated model was then used to study the influence of outlet conduit parameters on the performance of the pump, from which we proposed three outlet conduits with different outlet widths. The simulated hydraulic loss and flow pattern in the conduits with different plane diffusion angles, elevation diffusion angles and transition section lengths were analyzed using the single factor method. 【Result】 With the increase in the plane diffusion angle, the hydraulic loss in the outlet decreased first followed by an increase after the angle was larger than 17o. For elevation diffusion angle less than 7°, the hydraulic loss remained almost unchanged, while when it was larger than 7o, the hydraulic loss increased steadily. With the increase in the diffusion section length, the hydraulic loss decreased first followed by an increase when the relative length of the transition section was more than 0.6~0.8. When the hydraulic design parameters were within the normal range, we did not find bad flow patterns in the conduit. 【Conclusion】 When the design parameters are selected appropriately, the hydraulic loss of the outlet conduit of the front shaft tubular pump system can be minimized, and the pump system efficiency will be improved.

In the present study, relationships among all Chinese species of lacertids in the genus Eremias, E. velox, E. grammica, E. vermiculata, E. przewalskii, E. multiocellata, E. arguta, E. brenchleyi, and E. argus, were assessed using 574 aligned base positions of 16S rRNA mitochondrial DNA sequences from 103 individuals collected from 28 populations. Three kinds of phylogenetic tree (MP, ME, and NJ) were reconstructed and were found to be concordant. All eight species well form a monophyletic group. The resulting genetic distance between E. przewalskii and E. multiocellata is surprisingly low, only 0.008. The result could be due to introgression of the mtDNA molecule. All Eastern-Asia lacertids except E. vermiculata grouped together and formed a monophyletic clade. E. vermiculata are closely related to E. arguta, a Central-Asia species. E. brenchleyi and E. argus formed a monophyletic clade as the sister group of E. multiocellata. The Central-Asia species (E. arguta, E. grammica and E. velox) originated from Central-Asia and Eastern-Asia species (the rest) from China. The phylogenetic relationships among E. grammica, E. velox, E. arguta-vermiculata, E. argus-brenchleyi, and E. multiocellata-przewalskii are unclear in the study, which needs more comprehensive taxonomic sampling from Western Asia and Europe, and additional genetic evidence to resolve it. [ABSTRACT FROM AUTHOR]