无限集上严格保序变换半群的正则元及格林关系

设X是一个全序集,SOx是X上的严格保序变换半群.考虑X是一个全序无限集的情形.讨论了SOx中的正则元和SOx上的格林关系.证明了SOx中的元素α是正则的当且仅当α是双射.还证明了SOx的所有正则元形成SOx的一个极大子群.另外,给出了SOx上的格林关系L,R,D和H的刻划.SOx上格林关系的刻画对SOx的研究起重要作...     

Antidesigns and regularity of partial spreads in dual polar graphs

We give several examples of designs and antidesigns in classical finite polar spaces. These types of subsets of maximal totally isotropic subspaces generalize the dualization of the concepts of m ‐ovoids and tight sets of points in generalized quadrangles. We also consider regularity of partial spreads and spreads. The techniques that we apply were developed by Delsarte. In some polar spaces of small rank, some of these subsets turn out to be completely regular codes. © 2010 Wiley Periodicals, Inc. J Combin Designs 19: 202‐216, 2011     

Ahlfors 正则空间上的开集分解与加倍测度

对于一致完全的加倍度量空间建立了 Whitney 分解定理. 作为应用, 借助于 Ahlfors 正则空间上的加倍测度描述了它的任意非空闭集的 Whitney 修正集上的加倍测度.     

具有左简纯正断面的正则半群

本文引入并研究了左简纯正断面, 得到了与之相关的若干刻画; 推广并丰富了Blyth 和AlmeidaSantos 于1996 年得到的关于左简逆断面及Kong 于2007 年得到的关于纯正断面的相关结果; 同时,给出了具有左简纯正断面的正则半群的结构定理.     

Cubic semisymmetric graphs of order 8p~3

A regular edge-transitive graph is said to be semisymmetric if it is not vertex-transitive.By Folkman [J.Combin.Theory 3(1967),215-232],there is no semisymmetric graph of order 2p or 2p 2 for a prime p,and by Malni et al.[Discrete Math.274(2004),187-198],there exists a unique cubic semisymmetric graph of order 2p 3,the so called Gray graph of order 54.In this paper,it is shown that there is no connected cubic semisymmetric graph of order 4p 3 and that there exists a unique cubic semisymmetric graph of orde...     

Temperature impact on mechanically induced long-period fiber gratings

The spectral response of mechanically induced long-period fiber gratings (MLPFG) to the ambient temperature variation was experimentally study. In the MLPFG setting, a pressure rig with aluminum grooved plates on standard telecommunication fiber was used. We found that a relatively low change in temperature can produce a severe impact on the characteristic parameters of the attenuation bands, such as a critical decrease in the contrast and fast shift saturation. When the temperature increases from −10 to 70 °C, all the bands are shifted toward longer wavelengths with a mean sensitivity of approximately 180 pm/°C from 0 to 40 °C in the near-linear region, then they present a flattened zone beyond this temperature. Meanwhile, the contrast of the attenuation bands rapidly decreases from the maximum value to 0 dB with a quasi-cosinoidal behavior. These results are important and have to be considered when MLPFG are applied in a medium with ambient temperature variation. Furthermore, we show that MLPFG can be used as low cost ambient temperature sensors through intensity based measurements.     

Metabolomics study of cured tobacco using liquid chromatography with mass spectrometry: Method development and its application in investigating the chemical differences of tobacco from three growing regions

Cured tobacco is an important plant material. Component studies are a big challenge for its significantly diverse chemical properties and vastly different concentrations. In this work, liquid chromatography with quadrupole time‐of‐flight mass spectrometry was used to perform a metabolomics study of cured tobacco owing to its efficient separation and detection of semipolar metabolites. A solvent of methanol/water (8:2, v/v) and 30 min of ultrasound time were found to be optimal to perform extraction. 95, 92, and 93% of metabolite features had within 20% of coefficient of variation for repeatability, intraday and interday precision analysis, respectively, indicating a good stability of the method developed. 113 metabolites were identified in cured tobacco based on accurate mass, retention time, and MS/MS fragments. The developed method was applied to a metabolomics study of cured tobacco from three growing regions. Forty three metabolites were found to be contributed to the classification. It is shown that the developed method can be applied to metabolomics analysis of plant materials.     

变宽截面箱梁剪力滞效应研究

将变宽度截面箱梁的剪力滞翘曲位移函数定义为三次抛物线形式,用能量变分原理建立了分析变宽截面箱梁剪力滞效应的控制微分方程,并用差分法求解此方程。分别计算了简支箱梁在集中荷载和均布荷载作用下的正应力,并用有限元法作了验证。将计算结果与等截面箱梁的应力进行对比,总结变宽箱梁剪力滞效应的分布规律。结果表明,均布荷载作用下,相对于等截面梁,变宽箱梁的顶板应力变化幅度更大,峰值更高,箱梁的顶板宽度变化对剪力滞效应影响较大;在集中荷载作用下,等截面与变宽度箱梁跨中截面的应力相近,应力分布曲线吻合较好,说明顶板宽度变化对剪力滞效应影响较小;分别在集中和均布荷载作用下,箱梁跨中截面应力均为正剪力滞分布状态。当箱梁顶板、底板和悬臂板宽度相等时,剪力滞效应控制微分方程也适用于等截面箱梁。     

Multiple internal resonances of rotating composite cylindrical shells under varying temperature fields

Applied Mathematics and Mechanics - Composite cylindrical shells, as key components, are widely employed in large rotating machines. However, due to the frequency bifurcations and dense frequency...     

压电压磁复合材料中正六边形孔边裂纹的反平面断裂问题

基于线性磁电弹性理论,利用Schwarz-Christoffel(CS)变换技术和Stroth公式,首次系统研究了压电压磁复合材料中含带两个不对称裂纹的正六边形孔口问题在部分渗透磁电边界条件下的解析解.当忽略磁场时,磁电非渗透裂纹和磁电渗透裂纹两种极端情况下的解析解答可退化为文献已有研究结果.数值结果揭示了正六边形孔口尺寸、裂纹长度以及力电载荷和磁载荷对能量释放率的影响规律.研究结果表明：减小孔口边长和裂纹长度可以提高材料的可靠性;机械载荷总是促进裂纹扩展;在磁电非渗透和磁电部分渗透边界条件下,负电场和负磁场会延缓裂纹的扩展,而正电场可以增强或阻碍裂纹的扩展,这取决于所施加的电场和磁场的强度以及机械载荷的水平;在磁电渗透边界条件下,电场和磁场对裂纹的扩展没有影响.