不同产地独活及其混伪品的质量差异性分析

多点采样,对不同来源的独活及其混伪品进行质量差异性分析.测定不同产地独活及其混伪品总灰分、酸不溶性灰分、蛇床子素和二氢欧山芹醇当归酸酯质量分数,并结合HPLC指纹图谱对不同产地独活及其混伪品开展质量评价.结果表明,不同产地独活除陕西样品的蛇床子素略低于《中华人民共和国药典》(以下简称《药典》)标准外,其余样品均符合《药典》质量要求,而独活混伪品的蛇床子素质量分数均远低于正品独活质量分数.不同产地的独活HPLC指纹图谱有25个共有峰,各独活样品的指纹图谱与对照图谱的相似度在0.9以上,所建立的指纹图谱可用于独活的质量评价.因此,多指标的测定结果结合HPLC指纹图谱,可有效对不同产地的独活质量进行差异性分析和评价;混伪品蛇床子素的质量分数远低于正品独活,蛇床子素的质量分数高低可作为正品独活区别于混伪品的一个重要特征指标.     

The Life-Cycle Model with Optimal Retiring Age and Simulation

In this paper, a life-cycle model with retirement is set up to study how an individual chooses the optimal retiring age on account of wage growth rate, longevity and healthy state. It is proved that there exists optimal retiring age under given conditions. The numerical simulations are given to show how wage growth rate, longevity and healthy state affect retiring age.     

桩筏基础前排桩的工作参数分析研究

针对桩筏基础力学性能分析,基于荷载分担比率和曲线的代表性,主要研究参数改变下前排中层桩的力学性能改变.利用有限元软件ANSYS10.0为平台来模拟原位桩筏基础试验,针对横向荷载受力,考虑合理的网格划分、桩-土之间的滑动及脱离、边界条件等因素的影响并进行了模型验证.通过改变模型参数如桩距、桩长和桩径参数较准确的反映了桩筏基础的受力机理,有较好的参考价值.     

A Constrained Interval-Valued Linear Regression Model: A New Heteroscedasticity Estimation Method

Linear regression models for interval-valued data have been widely studied. Most literatures are to split an interval into two real numbers, i.e., the left- and right-endpoints or the center and radius of this interval, and fit two separate real-valued or two dimension linear regression models. This paper is focused on the bias-corrected and heteroscedasticity-adjusted modeling by imposing order constraint to the endpoints of the response interval and weighted linear least squares with estimated covariance matrix, based on a generalized linear model for interval-valued data. A three step estimation method is proposed. Theoretical conclusions and numerical evaluations show that the proposed estimator has higher efficiency than previous estimators.

     

食品中胺鲜酯的气相色谱-质谱联用仪测定方法研究

为检测食品中胺鲜酯残留量,以大米、白菜、玉米为研究对象,建立了食品中胺鲜酯的气相色谱-质谱联用仪测定方法。样品经丙酮微波萃取,固相萃取柱净化,氮吹浓缩,用气相色谱-质谱联用仪测定,外标法定量。结果表明:胺鲜酯在20~4000 ng/L范围内具有良好的线性关系(R=0.9999),方法检出限6μg/kg,定量限20μg/kg。在40~4000μg/kg的添加水平,胺鲜酯的回收率在95%~107%之间,方法精密度试验的相对标准偏差在5%以内。该方法适用于食品中胺鲜酯的定性和定量测定。     

含螺栓联接的转子系统轴向刚度不确定性分析

转子系统中螺栓联接结构轴向联接刚度的不确定性对转子系统动力学特性具有重要影响,为此,在构建螺栓联接结构有限单元基础上,建立了转子系统整体有限元模型,采用非嵌入多项式混沌展开法分析轴向联接刚度不确定性对转子系统动力学特性的影响.结果表明:轴向联接刚度在一定范围内变化会导致临界转速及临界转速对应的稳态响应幅值偏离预期,随着轴向刚度不确定性的标准差增大,盘竖直方向稳态响应均值降低.研究结果可为螺栓联接转子的设计提供理论参考.     

农业机械化：十年进展与发展方向

自2004年实施农机具购置补贴10年来,农业机械化水平得到了极大的提高：2013年底,耕收种综合机械化水平达到59.48%;农机结构不断优化;三大主粮作物的综合机械化水平分别为：小麦93.7%、水稻73.1%、玉米79.8%;农机服务组织也得到了长足的发展。进一步提高农机化水平,必须抓住薄弱环节,着力发展农机社会化服务。     

本征晶格缺陷对BNT铁电薄膜光响应性能的影响简

用溶胶-凝胶法在YSZ/Si衬底上制备Bi3．15 Nd0．85 Ti3 O12（BNT）铁电薄膜,研究了退火气氛和退火温度对BNT薄膜的光响应性能的影响。对不同退火气氛和退火温度下的BNT薄膜进行微观结构和光响应性能表征。研究结果表明：随着退火气氛中氧含量的降低,光响应增大,BNT薄膜中氧空位起到了为光生载流子传输提供通道的作用;随着退火温度的降低,光开启电压和饱和光电导增大,BNT薄膜中高密度的晶界虽然阻碍了光生载流子的迁移,却有利于使光生载流子在晶界处及时分开。     

Monitoring and analysis of shock wave in water for underwater drilling blasting

Taking the underwater reef blasting in Gulei sea channel of Xiamen Port as an example, the forming characteristic of shock wave in water for underwater drilling blasting is analyzed. By field monitoring, the pres- sure of shock wave in water for different distances is attained; the major parameters such as pressure amplitude and positive action time, and the propagation attenuation rule of shock wave in water are analyzed in this paper. The results can be helpful for engineering design and construction and environmental safety assessment.