排序方式: 共有56条查询结果,搜索用时 218 毫秒
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数值测量了卸载过程中二维单分散圆盘颗粒系统的横波、纵波声速、声衰减系数、非线性系数随压强的变化以及声衰减系数随频率的变化.结果表明,二维(2D)圆盘颗粒体系的横波、纵波声速均随压强呈分段幂律标度:当压强P10~(-4)时,横波、纵波声速随压强的增大而减小;当P10~(-4)时,有v_t~P~(0.202),v_l~P~(0.338).进一步得到其剪切模量和体积模量的比值G/B也随压强呈幂律标度,G/B~P~(-0.502),暗示在低压强下,与三维(3D)球形颗粒体系类似,2D圆盘颗粒体系也处于L玻璃态.水平激励和垂直激励下2D圆盘颗粒系统的衰减系数随频率变化也呈现分段行为:当频率f0.05时,衰减系数不随f变化;当f0.05时,横波纵波的衰减系数α~f;当f0.35时,横波衰减系数α_T~f~2,纵波衰减系数α_L~f~(1.5).此外,竖直水平激励下的2D圆盘颗粒系统的非线性系数和衰减系数随压强也呈现与声速类似的分段规律:当P10~(-4)时,横波非线性系数β_T~P~(-0.230),其余都不随压强变化.当P10~(-4)时,两者均随压强增大呈幂律减小:β_T~P~(-0.703),β_L~P~(-0.684),α_T~P~(-0.099),α_L~P~(-0.105).进而得到2D圆盘颗粒系统中散射相关的特征长度?~*随压强呈幂律标度,当P10~(-4)时,?~*~P~(-0.595);当P10~(-4)时,?~*~P~(0.236). 相似文献
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利用电子束蒸发方法将MgB2超导薄膜沉积到Al2O3(001)衬底上.采用标准的四引线法研究了磁场平行和垂直超导薄膜ab平面下的电阻转变.一个激活能模型 U(T,H)= U0(1-T/(Tc+δ))n (1-H/Hc2(0))m被建立用来分析超导薄膜磁通线的激活能和电阻转变,结果表明该模型能够在整个转变温度范围描述超导体磁通线的激活能和电阻转变.另外,利用多项式Hc2(t)=Hc2(0)+At+Bt2分析了MgB2/Al2O3超导薄膜的上临界磁场,获得了该超导薄膜的各向异性参数γ=Hc2ab(0)/Hc2c(0)= 2.26. 相似文献
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气相色谱-质谱法测定大气颗粒物中的有机胺类物质 总被引:1,自引:0,他引:1
建立了大气颗粒物中有机胺类物质的气相色谱-质谱(GC-MS)分析方法.样品用超纯水超声萃取,然后在碱性条件下,用苯磺酰氯(Benzenesulfonyl chloride,BSC)衍生化,衍生物用二氯甲烷萃取,最后用DB-5MS色谱柱分离测定,实现了13种有机胺(包括7种脂肪胺、2种杂环胺和4种芳香胺)的同时测定.本方法的仪器检出限(S/N=3)和定量限(S/N=10)分别为0.00008~0.017 μg/mL和0.00026~0.0565 μg/mL; 标准曲线线性相关系数为0.9903~0.9996,相关性良好;相对标准偏差(RSD)均小于30%, 除低浓度加标水平的甲胺和苯甲胺,其余样品基质加标平均回收率为54.4%~159.7%,大部分胺具有较高的精密度与准确度.将本方法应用于广州城区PM2.5样品的检测, 共检出有机胺9种,其中甲胺、二甲胺和二丁胺约占9种有机胺总和的90%,是PM2.5中主要胺类物质,而丙胺浓度最低,浓度小于1.0 ng/m3. 相似文献
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We present a scheme for probabilistic dense coding via quantum channels of non-maximally entangled threeparticle states. Quantum dense coding will succeed with a certain probability if the sender introduces an auxiliary particle and performs a collective unitary transformation. The average information transmitted in this scheme is calculated. 相似文献
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利用微带谐振技术研究了MgB2/A12O3和YBa2Cu3o7-X/LaAlO3(YBCO/LAO)超导薄膜的微波性质.一个颗粒尺寸模型被用来分析超导薄膜的穿透深度和表面电阻.结果表明,对于高质的YBCO/LAO,微波性质主要由颗粒决定.对于低质的MgB2/Al2O3,该薄膜的微波性质主要由颗粒边界决定. 相似文献
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以磷钨酸为催化剂 ,乙酰乙酸乙酯和乙二醇为原料 ,甲苯为带水剂合成了苹果酮。结果表明 ,磷钨酸催化剂具有活性高、选择性好、后处理简单的优点 相似文献
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By using the momentum theorem and waterbalance principle, basic equations of slope runoff were derived, soil erosion by raindrop splash and runoff were discussed and a model was established for decribing hillslope soil erosion processes. The numerical solution of the model was obtained by adopting the Preissmann format and considering the common solution-determining conditions, from which not only the runoff and soil erosion but also their processes can be described. The model was validated by ten groups of observation data of Soil Conservation Ecological Science and Technology Demonstration Park of Jiangxi Province. Comparisons show that the maximum relative error between simulation and experimental data is about 10.98% for total runoff and 15 % for total erosion, 5.2% for runoffprocess and 6.1% for erosion process, indicating that the model is conceptually realistic and reliable and offers a feasible approach for further studies on the soil erosion process. 相似文献