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1.
《Ceramics International》2022,48(6):8325-8330
In this work, we propose a facile approach to fabricate Ti4+-doped Li3V2(PO4)3/C (abbreviated as C-LVTP) nanofibers using an electrospinning route followed by a high temperature treatment. In this designed nanocomposite, the ultrafine LVTP dots are homogeneously dispersed into one-dimensional carbon nanofibers and the Ti4+ doping does not destroy the crystal structure of monoclinic Li3V2(PO4)3. Compared to the undoped Li3V2(PO4)3/C (abbreviated as C-LVP), the as-fabricated C-LVTP fibers present higher reversible capacity, superior high-rate capability as well as better cyclic property. Especially, the C-LVT7%P cathode delivers not only high capacities of 187.2 and 160.3 mAh g?1 at 0.5 and 10 C respectively, but also stable cyclic property with the reversible capacity of 135.8 mAh g?1 at 20 C following 500-cycle spans. The good battery characteristics of C-LVT7%P can be mainly ascribed to Ti4+ doping, which can increase the electrical conductivity and Li+ diffusion coefficient. 相似文献
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This study develops a 6-DOF mathematical model for a robotic fish that considers surge, sway, heave, roll, pitch, and yaw. The model considers the conditions of a fish swimming in ocean current perturbations similar to the ocean current perturbations of the slender-body autonomous underwater vehicles. For swimming and turning behaviors, a nonlinear, dynamic, carangiform locomotion model is derived by using a planar four-link model. A 2-DOF barycenter mechanism is proposed to provide body stabilization and to serve as an actuating device for active control design. A barycenter control scheme is developed to change the center of gravity of the robot fish body by moving balancing masses along two axes. The projected torque on x and y axes propel pitch and roll angles to the desired settings. A Stabilizing controller, fish-tail mechanism, rigid body dynamics, and kinematics are incorporated to enable the fish robot to move in three dimensional space. Simulation results have demonstrated maneuverability and control system performance of the developed controller which is proposed to conduct path tracking of the robot fish as it swims under current perturbations. 相似文献
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This research is concerned with the problem of 4 degrees of freedom (DOF) ship manoeuvring identification modelling with the full-scale trial data. To avoid the multi-innovation matrix inversion in the conventional multi-innovation least squares (MILS) algorithm, a new transformed multi-innovation least squares (TMILS) algorithm is first developed by virtue of the coupling identification concept. And much effort is made to guarantee the uniformly ultimate convergence. Furthermore, the auto-constructed TMILS scheme is derived for the ship manoeuvring motion identification by combination with a statistic index. Comparing with the existing results, the proposed scheme has the significant computational advantage and is able to estimate the model structure. The illustrative examples demonstrate the effectiveness of the proposed algorithm, especially including the identification application with full-scale trial data. 相似文献
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Liu Xiao-zhou Liu Ying-zhong Miao Guo-ping School of Naval Architecture Ocean Engineering Shanghai Jiaotong University Shanghai China 《水动力学研究与进展(B辑)》2001,(1)
1 . INTRODUCTIONWhenhigh speedairfloworcurrentpassesovergapsorcavitiesinaflatplate ,self excitedoscillationsmayoccur ,leadingtodramaticpressureandvelocityfluctuationandintensivenoise .Thesephenomenamayappearinmanyengineeringapplications .Forexample ,weaponb… 相似文献
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《Cement and Concrete Composites》2007,29(9):700-711
Surface opening cracks are common defects in large civil structures like bridges. They allow penetration of water or other agents that result in loss of durability earlier than expected. Their repair can be conducted by the injection of epoxy material that seals the crack sides keeping out any aggressive substances in addition to the recovery of strength. In order to evaluate crack parameters before impregnation as well as to determine the final repair effectiveness, a combination of Rayleigh and longitudinal waves is applied. Rayleigh waves demonstrate the filling condition of the material into the shallow layer near the surface while tomography using longitudinal waves through the thickness yields information about the area inside the structure. Wave propagation dispersion features are exploited by the proposed tomography at different frequencies, demonstrating that higher frequencies lead to more accurate characterization. 相似文献
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A simplified two-dimensional model of two-layer porous burner based on pore level is developed.The heat transfer of solid phase in porous burner is seen as the synergistic effects of conduction through con-necting bridges and surface radiation between the solid particles in the model.A numerical simulation study on the characteristics of flow,combustion and heat transfer in the two-layer porous burner is car-ried out using the pore level model,and the effects of the control parameters such as the inlet velocity and solid thermal conductivity on thermal non-equilibrium are investigated.The results show that the flame structure is highly two-dimensional based on pore level.Obvious thermal non-equilibrium in the burner for the two phases and solid phase are observed,the largest temperature difference between the gas and solid phases is observed in combustion zone,while the temperature difference inside the solid particles is largest near the flame front.The results also reveal that thermal non-equilibrium of por-ous burner is much affected by the inlet velocity and solid thermal conductivity. 相似文献
9.
《Fuel》2006,85(12-13):1772-1780
With a view to developing onboard generation of selective reductants for NOx removal from diesel engine exhaust we compared the performance of a primary, secondary and tertiary amine to NH3 using a typical mini core NH3-SCR catalyst. Primary amines with short hydrocarbon chains, e.g. CH3NH2 (maximum NOx conversion, 50%) approached the NOx conversion obtained using NH3 (maximum NOx conversion, 70%). Increasing the amine to NOx ratio greater than 1 results in NOx conversions closer to those of NH3 (maximum NOx conversion increased to 60%). Secondary and tertiary amines had smaller NOx conversions as a function of temperature and the drop in NO and NOx conversion decreased with increasing amine hydrogen substitution. Also, the maximum NOx conversion for each reductant tends to move to a lower temperature as the degree of substitution increases.Unlike NH3, the amines can react in the gas phase at temperatures within the range of diesel engine exhaust. Due to this gas phase reactivity the NOx conversions measured using the mini core SCR catalyst also contain a gas phase conversion component. Gas phase conversions were investigated by replacing the mini core SCR catalyst with an equivalent length of quartz beads. Subtraction of the two results highlighted the differences between the mini core catalytic and gas phase conversions measured in this manner over the temperature range investigated. These differential NOx conversions for the three amines had maxima at about 375 °C. 相似文献
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