UPLC-Q/TOF-MS coupled with multivariate analysis for comparative analysis of metabolomic in Dendrobium nobile from different growth altitudes

Dendrobium nobile alkaloids (DNLA) and glycosides are the main active components extracted from Dendrobium nobile Lindl. (D. nobile) used for thousands of years in China. The pharmacological effects of the above chemical components are significantly different. D. nobile is mainly grown at an altitude ranging from 230 to 800 m in Chishui City, Northwest Guizhou Province. However, it is unclear whether the metabolite in D. nobile is influenced by the planting altitude. Hence, to reveal the different metabolite in D. nobile cultivated at the altitude of 336 m, 528 m, and 692 m, ultra-high performance liquid chromatography with Q/TOF-MS couple with multivariate analysis were developed. Using the orthogonal partial least squares-discriminant analysis, 19 different metabolites were discovered and then tentatively assigned their structures as alkaloids and glycosides by comparing mass spectrometry data with in-house database and literature. Moreover, the result of semiquantitative analysis showed the content of dendrobine that was belonged to alkaloids significantly increased at the altitude of 692 m, whereas the content of glycosides demonstrated an accumulation trend at the altitude of 528 m. The results could provide valuable information for the optimal clinical drug therapeutics and provide a reference for quality control.     

An analysis of peak overpressures in vented gaseous explosions

Experimental data from vented explosion tests using stoichiometric methane–air and 18% hydrogen–air mixtures in a 63.7 m³ chamber with a 2.7 or 5.4 m² vent are presented. Results from experiments conducted using stoichiometric propane–air in 2.42 m³ vessel with a 0.26 m² vent are also reported. The tests were focused on the effect of fuel, enclosure size, ignition location, vent size, and obstacles on the pressure development of a propagating flame in a vented enclosure. The dependence of the maximum pressure generated on the experimental parameters was analyzed. It was found that the pressure maxima may be caused by pressure transients controlled by the interplay of the maximum-flame area, the burning velocity, and the overpressure generated by an external explosion. A simple model was proposed to estimate the maximum pressure for each of the main pressure transients. The model was found to agree with the experimental data within the experimental uncertainty.     

机动方舱核爆炸冲击波动力响应和安定性分析

本文以核爆炸当量、高度、距离为参数，采用等超压圆给出了普通方舱和防核加固方舱结构在核冲击波下的安全域。研究了限制舱体倾斜的压力条件。本文还以冲击波压力的时间函数为激励，求解了方舱的动力响应。从试验结果推论和计算模拟两方面，分析了方舱承受冲击波的能力。     

平面坡体渐进破坏模型及其应用

平面坡体渐进破坏模型旨在通过在坡体稳定性分析中引进渐进坡坏的概念,来较合理地考虑岩土材料的峰值强度和残余强度在稳定性分析中的不同作用。通过与其它稳定性分析方法进行比较以及实例应用研究,证明该计算模型可用于初步判断坡体稳定状态并估算其破坏变形范围。这一研究也说明了水对边坡破坏的重要作用。     

Numerical and empirical modeling of peak deceleration and stress analysis of polyurethane elastomer under impact loading test

In this work, we present the modeling of the peak deceleration (PD) using data of the experimental drop test. Specimens with different thicknesses and areas tested in the drop test device which has adaptable height and weight. In the empirical modeling of the PD, the thickness, area, drop mass and drop height considered as separable functions. An analytical model and Neural Network (NN) was used as the empirical models. Further, the stress on the material was calculated using differential equations and the Finite Element Method (FEM). The Obtained PD from the experimental test, analytical and NN models was converted to the stress on the material using a derived differential equation. Finally, the best model for analyzing the PD and Stress on the material was presented.     

基于二极管阵列检测器的色谱峰纯度的快速直观鉴定

基于二极管阵列检测器（DAD）得到的色谱-光谱图,通过去噪、归一化、计算欧氏距离,聚类分析等方法,建立了一种快速直观的评价色谱峰纯度的有效方法：可直观的判断色谱峰的纯度,并判断存在干扰峰的位置,为色谱工作者评价色谱峰,进行下一步工作提供了依据。     

Nondestructive evaluation for remanent life of modified 9Cr-1Mo steel by reversible magnetic permeability

We present a magnetic and nondestructive method to evaluate the remanent life of modified 9Cr-1Mo steel by measuring the reversible magnetic permeability. Specimens with ten different kinds of aging periods were prepared using an isothermal heat treatment at 690 °C. The Larson-Miller parameter (LMP) was calculated and the peak interval of reversible magnetic permeability (PIRMP) was measured using the surface type probe. PIRMP was inversely proportional to LMP. We can evaluate the remanent life of modified 9Cr-1Mo steel using the relationship between PIRMP and LMP. Also, we present the possibility that the tensile strength and yield strength measured by destructive methods could be estimated by PIRMP measured nondestructively.     

基于多尺度小波变换的红外光谱谱峰识别算法

传统的谱峰检测方法一般分为3个步骤:谱线平滑、基线校正和谱峰识别.现有的基于小波变换的峰值检测方法能较好地将基线校正和谱峰识别两个步骤融为一步.在此基础之上,本研究将谱线平滑也很好地融入到小波变换的峰值检测算法中,使整个峰值检测算法成为一个整体.在峰值提取时,原始谱图直接处理,不再是处理加工过的谱图,减小了谱峰检测结果...     

中心引爆破片战斗部产生的近区空气爆炸波的计算

本文提出一种计算中心起爆有限装药尺寸破片战斗部产生的近区空气爆炸波超压的近似方法。战斗部壳体碎片除受爆轰产物的推力及空气反压外,还考虑了碎片形状等因素引起的形阻修正。适当选取形阻修正系数及修正项引入时刻,计算数据与数十公斤装药战斗部近区实验结果十分接近。本文结果表明,爆破战斗部近区空气爆炸波的计算不能采用强爆炸波理论,应当考虑飞片驱动冲击波的模型。