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The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solutionbased method with basic chromium(III) nitrate solution (pH=11.9). And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 particles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, LixCr2O3, formed by the lithiation of Cr2O3, can further stabilize Li7Ti5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution (pH=3.2) modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to improve the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At-20℃, its reversible specific capacity was still as high as 118 mAh/g. 相似文献
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高速磁浮列车气动噪声分布规律研究 总被引:1,自引:0,他引:1
本文基于上海线高速磁浮列车现场噪声测试,结合数值仿真分析了磁浮列车行驶时的噪声特性以及气动噪声分布规律.数值仿真采用延时分离涡结合声比拟的方法,并对比现场测试噪声数据,给出了高速列车气动噪声特性以及噪声源分布规律.研究结果表明:列车行驶时噪声时程呈现很强脉冲性,频率小于100 Hz噪声主要来源于与高架桥梁结构振动相关的二次辐射噪声,特别是次声频段内,桥梁自振会产生显著的噪声.磁浮列车表面气动噪声分布规律与噪声频率相关,低频噪声与列车的车尾涡脱相关,高频噪声由车头边界层分离以及再附着、车身边界层流动等引起,而中频噪声主要产生于列车底部、抱轨与轨道梁表面相对运动作用.因此,高速磁浮列车除了要重点考虑车头、车尾的气动外形对气动噪声的影响外,还应考虑轨道间隙处气动噪声及其分布规律. 相似文献
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鱼生作是消费者钟爱的菜式之一,其品质主要受蛋白质、脂肪、含水率指标影响。传统品质检测操作繁琐、检测时间长、专业要求高,无法满足产业品质快速监管需求。因此,以草鱼生鱼片为研究对象,用点光谱(光纤光谱)、面光谱(高光谱成像)技术作为研究手段进行对比,探究一种快速、高效的生鱼片蛋白质、脂肪、含水率检测方法。研究发现:点光谱技术在鱼生鱼片品质无损检测上比面光谱技术更优,其光谱数据经卷积平滑法(SG)+标准正态变量变换(SNV)+竞争性自适应加权算法(CARS)+偏最小二乘(PLSR)建模后,蛋白质的指标训练集决定系数(R2)为0.995 7,均方根误差(RMSE)为0.000 6,验证集决定系数(R2)为0.941 9,均方根误差(RMSE)为0.002 4;脂肪指标训练集R2为0.999 3, RMSE为0.000 6,验证集R2为0.997 6, RMSE为0.001 7;含水率训练集R2为0.999 2, RMSE为0.001 7,验证集R2为0.094 1... 相似文献
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