| 1 | LA-ICP-MS U-Pb zircon geochronology and Hf isotope, geochemistry and kinetics of the Daxigou anorthosite from Kuruqtagh block, NW China显示文摘Kuruqtagh block is the best area for Precambrian geology in Xinjiang Autonomous Region, NW China, since it exposed complete Precambrian lithology units. The study of this ancient base will deepen the understanding of the Precambrian evolution of the Tarim Basin. In this paper, we studied the petrology, geochemistry, zircon LA-ICPMS U-Pb chronology and zircon Hf isotope of Daxigou anorthosite(DA) which is located at the northern margin of Tarim craton and discussed the rock formation, tectonic and geological significance. Zircons from the intrusions display oscillatory zoning and high Th/U ratios(0.39–1.35), implying their magmatic origin. Zircon LA-ICP-MS U-Pb dating results indicate that they formed during the Paleoproterozoic age with the weighted 206Pb/238 U average age of 1818±9 Ma, which is significantly different from former's Neoproterozoic age, and is coincidentally identical with its associated syenite granite age within the error range. Studies on petrogeochemistry suggest that DA belongs to medium-sodium peraluminous alkaline type, rich in Pb, La, Th and LILE, and poor in HFSE(Gd, Nd, and Ta). The chondrite-normalized REE pattern is slightly to the right form. The average ∑REE is 317.2×10-6; HREE show moderate fractionation [average LREE/HREE is 14.71, average(La/Yb)N is 24.77; average(La/Sm)N is 3.85, and average(Gd/Yb)N is 3.46]; and the δEu and δCe are not obvious. Their initial Hf isotope ratios and Hf two-stage model ages range from-6.6 to-4.43 and 2.63 to 2.74 Ga, respectively. Taken together, it is suggested that Daxigou anorthosite is a typical volcanic anorthosite and its primary magma could be contaminated by the partial melt Neoarchaean crust and mainly formed in the arc environment, which recoded the tectonic-magma activities response of the Tarim refers to the amalgamation of the supercontinent Columbia. | YUAN Qian CAO Xiaofeng Lü Xinbiao WANG Xiangdong YANG Enlin LIU Yuegao RUAN Banxiao LIU Hong MUNIR Mohammed Abdalla Adama | 2014 | Chinese Journal Of Geochemistry2014，33，3： | 2 |
| 3 | Optimal Designs of Wound Field Switched Flux Machines with Different DC Windings Configurations显示文摘Wound field switched flux(WFSF)machines exhibits characteristics of the simple robust rotor,flexible flux-adjustable capability,and no risk of demagnetization.However,they suffer from a poor torque density compared with permanent magnet machines due to the saturation.Therefore,in this paper,two WFSF machines with single-and double-layer DC windings,respectively,are optimized for the maximum torque.The end-winding(EW)lengths differ in these two machines,which can affect the optimal design.Design parameters including the DC to armature winding copper loss ratio,slot area ratio and split ratio are optimized when two machines have the same copper loss and overall sizes.In addition,the influence of the flux density ratio,total copper loss,air-gap length and aspect ratio on the optimal split ratio is investigated using the finite element method and results are explained through the analytical model accounting for the saturation.It is discovered that the EWs have no effect on the optimal copper loss ratio,which is unity.In terms of the slot area ratio,the machine with single-layer DC windings prefers smaller DC slot areas than armature slot areas.In the WFSF machine with longer EWs,the optimal split ratio becomes smaller.Moreover,compared with other parameters,the flux density ratio can significantly affect the optimal split ratio. | Wenting Wang Yuankui Wang Enlin Ma Lijian Wu | 2022 | CES Transactions on Electrical Machines and Systems2022，6，4： | 0 |
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