多氯代二苯并呋喃在不同色谱柱上的气相色谱保留行为——定量结构-色谱保留关系(QSRR)的研究

 以一种拟原子的方式处理多氯代二苯并呋喃 (PCDFs)异构体中的苯环 ,将PCDFs异构体中的原子或基团分为 3类 ,即 :氯原子 (Cl) (记为“1”) ,氧原子 (O) (记为“2”)及拟原子 (B) (记为“3”)。在烷烃分子距边矢量的基础上 ,提出一种以基团为基准的分子距离边数矢量 (μ矢量 ) ,借助多元线性回归方法分别建立了多氯代二苯并呋喃在不同色谱柱上的色谱保留指数与表征其结构的 μ矢量间的定量结构 色谱保留关系 (QSRR)相关模型。各样本总体所建模型的相关系数均在 0 98以上。     

High Resolution Crossed Beams Scattering Study of the F＋HD→DF＋H Reaction

Crossed beams scattering study was carried out on the F＋HD→DF＋H reaction using high- resolution H-atom Rydberg tagging time-of-flight technique. Vibrational state-resolved differential cross sections were measured, with partial rotational state resolution, at eight collision energies in the range of 2.51-5.60 kJ/mol. Experimental results indicated that the product angular distributions are predominantly backward scattered. As the collision energy increases, the backward scattered peak becomes broader gradually. Dependence of product vibration branching ratios on the collision energy was also determined. The experimental results show that the DF products are highly inverted in the vibrational state distribution and the DF （v＇=3） product is the most populated state. Furthermore, the DF （v＇=l） product has also been observed at collision energy above 3.97 kJ/mol.     

Structural Characterization and Retention Time Prediction for Components of Essential Oil of Meconopsis Integrifolia Flowers

A molecular structural characterization (MSC) method called reduced molecular electronegativity-distance vector (MEDVR) was used to describe the molecular structures of 55 components of meconopsis integrifolia flowers. By use of stepwise multiple regression (SMR) and partial least square (PLS) methods, a model with the correlation coefficient (R1) of 0.987 and the standard deviation (SD1) of 1.377 could be obtained. Then through multiple linear regression (MLR), another model with the correlation coefficient (R2) of 0.989 and standard deviation (SD2) of 1.395 could be constructed. Furthermore, in virtue of variable screening by the stepwise multiple regression technique (SMR), 8 vectors were selected to build up another model with its correlation coefficient (R3) and standard deviation (SD3) of 0.989 and 1.366, respectively. Then all the three models were evaluated by performing cross-validation with the leave-one-out (LOO) procedure, and the correlation coefficients (QCV) were 0.981, 0.976 and 0.979, respectively. The results show that the models constructed could provide estimation stability and favorable predictive ability.     

烹饪过程中锅具运动姿态测量方法

提出一种用于跟踪烹饪时锅具运动姿态变化的方法.该方法将MEMS陀螺仪、加速度计以及地磁传感器正交三元组安装于锅具柄部,并将其输出信息经过硬件滤波、软件误差补偿之后利用REQUEST算法进行融合.REQUEST算法与EKF算法相同之处在于均为以四元数为基础的迭代算法,而REQUEST算法由于其不易受锅具线加速度影响的特点而表现出优越性.文末通过仿真和实验对该方法进行了验证,并对REQUEST与EKF两种数据融合算法进行了比较,结果显示,即使在锅具高速运动情况下,由REQUEST算法得到的姿态解算精度仍可在以内,而此时由EKF算法得到的解算误差已达以上.上述结果表明,该文提出的方法对于测量锅具运动姿态而言是适用的.     

高校既有建筑地面抗滑性能试验研究

在滑倒摔伤事故中地面光滑是1个关键因素,以往许多研究都是在实验室内进行的,而本研究是用建筑地面抗滑性能测定仪对大学校园的干燥和潮湿2种地面条件进行了实地检测,考虑了不同湿水时间、不同测试方向以及橡胶机械磨损对地面摩擦系数的影响。通过对某食堂地面的测定来说明不同测试位置对地面摩擦的影响,并比较了潮湿条件下的摩擦损失值。为了确定静摩擦系数和动摩擦系数可能的相关性,对所测得的数据进行了线性回归分析。     

Multi-scale magnetic resonance measurements and validation of Discrete Element Model simulations

This short review describes the capabilities of magnetic resonance (MR) to image opaque single- and two-phase granular systems, such as rotating cylinders and gas-fluidized beds operated in different fluidization regimes. The unique capability of MR to not only image the solids’ distribution (voidage) but also the velocity of the particulate phase is clearly shown. It is demonstrated that MR can provide measurements over different length and time scales. With the MR equipment used for the studies summarized here, temporal and spatial scales range from sub-millisecond to hours and from a few hundred micrometres to a few centimetres, respectively. Besides providing crucial data required for an improved understanding of the underlying physics of granular flows, multi-scale MR measurements were also used to validate numerical simulations of granular systems. It is shown that predictions of time-averaged properties, such as voidage and velocity of the particulate phase, made using the Discrete Element Model agree very well with MR measurements.     

SURFACE STRESS EFFECT IN MECHANICS OF NANOSTRUCTURED MATERIALS

This review article summarizes the advances in the surface stress effect in mechanics of nanostructured elements,including nanoparticles,nanowires,nanobeams,and nanofilms,and heterogeneous materials containing nanoscale inhomogeneities.It begins with the fundamental formulations of surface mechanics of solids,including the definition of surface stress as a surface excess quantity,the surface constitutive relations,and the surface equilibrium equations.Then,it depicts some theoretical and experimental studies of the mechanical properties of nanostructured elements,as well as the static and dynamic behaviour of cantilever sensors caused by the surface stress which is influenced by adsorption.Afterwards,the article gives a summary of the analytical elasto-static and dynamic solutions of a single as well as multiple inhomogeneities embedded in a matrix with the interface stress prevailing.The effect of surface elasticity on the diffraction of elastic waves is elucidated.Due to the difficulties in the analytical solution of inhomogeneities of complex shapes and configurations,finite element approaches have been developed for heterogeneous materials with the surface stress.Surface stress and surface energy are inherently related to crack propagation and the stress field in the vicinity of crack tips.The solutions of crack problems taking into account surface stress effects are also included.Predicting the effective elastic and plastic responses of heterogeneous materials while taking into account surface and interface stresses has received much attention.The advances in this topic are inevitably delineated.Mechanics of rough surfaces appears to deserve special attention due to its theoretical and practical implications.Some most recent work is reviewed.Finally,some challenges are pointed out.They include the characterization of surfaces and interfaces of real nanomaterials,experimental measurements and verification of mechanical parameters of complex surfaces,and the effects of the physical and chemical processes on the surface properties,etc.     

数字梯度敏感方法及其在航空透明件断裂力学中的应用

本文将数字梯度敏感方法用于航空透明件断裂力学问题研究。首先,基于透明材料的弹性-光学效应,建立了透明件应力状态与光线穿过透明件后的偏转角之间的关系。在平面应力假设下,利用最小二乘拟合建立了I型裂纹尖端应力强度因子与光学偏转角的关系。其次,通过数字梯度敏感方法搭建非接触光学测试平台,开展了带单边裂纹的航空有机玻璃试件三点弯曲实验,应用数字梯度敏感方法提取了I型裂纹尖端应力强度因子。最后,通过选择不同计算子区域和步长大小,分析了数字梯度敏感方法中的子区域和步长选择对计算结果的影响。研究结果表明,数字梯度敏感方法实验所得应力强度因子与经验公式计算所得结果偏差小于10%,通过增加最小二乘拟合项数以及合理的子区域和步长选择可以减小数字梯度敏感方法计算应力强度因子误差。     

FUNDAMENTALS OF TRANSMISSION FLUCTUATION SPECTROMETRY WITH VARIABLE SPATIAL AVERAGING

Transmission signal of radiation in suspension of particles performed with a high spatial and temporal resolution shows significant fluctuations,which are related to the physical properties of the particles and the process of spatial and temporal averaging.Exploiting this connection,it is possible to calculate the particle size distribution (PSD) and particle concentration.This paper provides an approach of transmission fluctuation spectrometry (TFS) with variable spatial averaging,The transmission fluctuations are expressed in terms of the expectancy of transmission square (ETS) and are obtained as a spectrum,which is a function of the variable beam diameter.The reversal point and the depth of the spectrum contain the information of particle size and particle concentration,respectively.     

有限宽板孔边弹塑性变形测试

测量应变集中区域的弹塑性变形，对于研究材料损伤或微裂纹的产生，以预防宏观裂纹的产生及扩展具有重要的意义。为给航空发动机轮盘的损伤容限设计研究提供相关材料的力学实验参数，做了两个有限宽中心带孔试件的拉伸试验。试验中，采用单调逐级加、卸栽的循环加栽方式，并应用自动网格法和数字图像相关技术测量了孔用的全场位移分布。再应用最小二乘法将离散的位移分量拟合成二元多项式函数，求解出拉伸方向的应变分布，并给出孔边应力σ与孔边应变εy的关系曲线。