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The high performance of an electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of electroactive materials.A porous core-shell architecture in which one-dimensional cobalt oxide(Co_3O_4)nanowire cores are grown on nickel foam prior to the growth of layered double hydroxide(LDH)shells is fabricated.Hydrothermal precipitation and thermal treatment result in homogeneous forests of 70-nm diameter Co_3O_4 nanowire,which are wrapped in LDH-nanosheet-built porous covers through a liquid phase deposition method.Due to the unique core-shell architecture and the synergetic effects of Co_3O_4and NiAl-LDH,the obtained Co_3O_4@LDH electrode exhibits a capacitance of 1 133.3F/g at a current density of 2A/g and 688.8F/g at 20A/g(5.3F/cm~(2 )at 9.4mA/cm~(2 )and 3.2F/cm~(2 )at 94mA/cm~2),which are better than those of the individual Co_3O_4nanowire.Moreover,the electrode shows excellent cycling performance with a retention rate of 90.4%after 3 000cycles at a current density of 20A/g. 相似文献
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搅拌头形状对焊缝塑化金属流动行为的影响 总被引:2,自引:0,他引:2
本文研究了搅拌形状对焊接过程中焊缝塑化金属流动行为的影响,使用了4种形式的搅拌头,(a)带反螺纹的圆柱形搅拌头,(b)带正螺纹的圆柱形搅拌头,(c)带反螺纹的圆锥形搅拌头,(d)带反螺纹的凸轮形搅拌头。研究结果表明,焊接过程中,焊缝塑化金属存在三种运动:表层的水平圆周运动、探针周围的螺旋运动、塑化环外围的刚塑性运动。搅拌头形状是影响焊缝塑化金属流动形态的主要因素。搅拌头探针表面的螺纹旋转方向不同,塑化金属的受力状态不同,探针周围金属朝上或朝下螺旋运动,从而带动周围金属流动;探针形状不同,可以改变塑化金属的流动性。 相似文献
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针对高脉冲重复频率脉冲多普勒(HPRF-PD)体制的相控阵主动雷达导引头中存在的距离遮挡问题,设计了一种新的波形选择策略。首先,利用提出的脉冲重复频率(PRF)波形选择策略,离线计算得到距离对应PRF的波形查找表。然后,通过叉积自动频率控制环路滤波(CPAFCLF)算法预估下个相参处理间隔(CPI)导引头与目标间的径向相对速度,并联合提出的基于Sage-Husa带有速度预测的自适应"当前"统计模型(SH-ACSMVP)算法得到的距离跟踪值,获得下个CPI的距离预测值。在跟踪机动目标场景中,相比于"当前"统计(CS)模型跟踪算法及基于"当前"统计模型的自适应无迹卡尔曼滤波(CAUKF)算法,本文算法得到的距离预测误差更小,误差收敛速度更快。根据此距离预测值从波形查找表中选择波形发射,作为下个CPI的发射波形,实现后续跟踪阶段的抗距离遮挡,提高目标跟踪性能。仿真结果表明了本文所设计波形选择策略的正确性及有效性。 相似文献
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结合“风云一号”C9(FY-1C)卫星姿轨控地面测试系统的研制实践,阐述了为适应卫星型号研制中试验任务多变,试验场所多变的特点,地面测试系统应采用先进的主流总线技术,充分利用计算机应用的领域的现有成果,遵循通用化,系列化,组合化的“三化”要求,研制性能价格比高的地面自动化测试系统,卫星在轨的正常运行,证明了该系统的有效性。 相似文献
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We conduct an in-depth study on the shape error of initially curved antennas to investigate errors that occur in the design and manufacturing processes. First, a numerical model is developed to simulate the actual surfaces. This model features a main advantage that it can predict the effects of cutting patterns on the shape error. The model is used to evaluate and optimize the design of cutting patterns. An error sensitivity analysis is performed to quantify and distinguish between the effects of error sources in manufacturing. The following sources are analyzed: errors in the elastic modulus of the membrane, pressure variations, and boundary deviations. The boundary deviation is found to be the most significant error source, and thus, boundary perturbation is recommended as an efficient error control measure. Finally, an inflatable antenna model is used to experimentally validate the numerical model. The experimental results display acceptable agreement with the numerical results. Thus, the developed numerical model and error control measure are shown to be feasible and efficient. 相似文献
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Helmut Lammer Eric Chassefière Özgür Karatekin Achim Morschhauser Paul B. Niles Olivier Mousis Petra Odert Ute V. Möstl Doris Breuer Véronique Dehant Matthias Grott Hannes Gröller Ernst Hauber Lê Binh San Pham 《Space Science Reviews》2013,174(1-4):113-154
The evolution and escape of the martian atmosphere and the planet’s water inventory can be separated into an early and late evolutionary epoch. The first epoch started from the planet’s origin and lasted ~500 Myr. Because of the high EUV flux of the young Sun and Mars’ low gravity it was accompanied by hydrodynamic blow-off of hydrogen and strong thermal escape rates of dragged heavier species such as O and C atoms. After the main part of the protoatmosphere was lost, impact-related volatiles and mantle outgassing may have resulted in accumulation of a secondary CO2 atmosphere of a few tens to a few hundred mbar around ~4–4.3 Gyr ago. The evolution of the atmospheric surface pressure and water inventory of such a secondary atmosphere during the second epoch which lasted from the end of the Noachian until today was most likely determined by a complex interplay of various nonthermal atmospheric escape processes, impacts, carbonate precipitation, and serpentinization during the Hesperian and Amazonian epochs which led to the present day surface pressure. 相似文献