实对称型上的Schur子空间及应用

本文构作了Schur型多项式,将其作为研究实对称型的基础.研究了具有零点(1,1,...,1)的实对称型形成的子空间,即Schur子空间.建立了这种子空间的构造性理论,并应用于计算(构造)实代数几何中比较关心的对称型正性判定问题,以及给出一些特殊类型的Hilbert第17问题的构造解.     

矩阵方程AX=A+X有正定解和幂零解的充要条件

给出了矩阵方程AX=A+X有解、实对称解、正定解和幂零解的充要条件.     

基于遗传算法的光综合孔径圆周阵优化

从光综合孔径圆周阵列成像的基本原理出发,建立了圆周阵列的优化模型;采用改进的实数编码方法对子孔径阵列位置进行编码,运用遗传算法进行子孔径阵列的优化;以阵列的u-v覆盖点间距最大化及最小冗余度来设计目标函数,实现了8~16个子孔径二维圆周阵的优化排列;分析了二维圆周光综合孔径阵列成像系统的点扩展函数、光学传递函数和衍射成像的基本原理;对优化结果与模拟退火算法的结果进行对比,使用仿真成像程序分析其点扩展函数,并与均匀排布的圆周阵列进行对比。结果表明,采用改进的实数编码的遗传算法可以很好地解决综合孔径阵列优化的问题,相对于模拟退火算法,该方法的计算时间更短,结果更优。     

光纤光栅压力传感器在列车实时追踪系统中的应用

随着外界应力的变化 ,光纤光栅的Bragg中心反射波长将发生相应的移动。利用此特性 ,与计算机监控相结合 ,研制出一种光纤光栅压力传感系统 (FBG) ,测量时间约 1ms/点 ,该系统可广泛用于列车实时追踪 ,实现列车的定位、速度与加速度计算等 ,并可以对列车脱节等事故及时作出判断     

Fitting continuum wavefunctions with complex Gaussians: Computation of ionization cross sections

We implement a full nonlinear optimization method to fit continuum states with complex Gaussians. The application to a set of regular scattering Coulomb functions allows us to validate the numerical feasibility, to explore the range of convergence of the approach, and to demonstrate the relative superiority of complex over real Gaussian expansions. We then consider the photoionization of atomic hydrogen, and ionization by electron impact in the first Born approximation, for which the closed form cross sections serve as a solid benchmark. Using the proposed complex Gaussian representation of the continuum combined with a real Gaussian expansion for the initial bound state, all necessary matrix elements within a partial wave approach become analytical. The successful numerical comparison illustrates that the proposed all-Gaussian approach works efficiently for ionization processes of one-center targets.     

Ricci η‐recurrent real hypersurfaces in 2‐dimensional nonflat complex space forms

Let M be a Hopf hypersurface in a nonflat complex space form $M^2(c)$, $c\ne 0$, of complex dimension two. In this paper, we prove that M has η‐recurrent Ricci operator if and only if it is locally congruent to a homogeneous real hypersurface of type (A) or (B) or a non‐homogeneous real hypersurface with vanishing Hopf principal curvature. This is an extension of main results in [17, 21] for real hypersurfaces of dimension three. By means of this result, we give some new characterizations of Hopf hypersurfaces of type (A) and (B) which generalize those in [14, 18, 26].     

Flows in networks with delay in the vertices

Our goal is to show asynchronous exponential growth (AEG) for a flow in a network with delay in the vertices. For this purpose we show first that its wellposedness can be characterized via an appropriate operator being the generator of a strongly continuous semigroup. We investigate the long term behavior of the system via the spectrum of this generator using techniques from operator matrices, Hille‐Yosida operators and positive semigroups. Finally, we apply our results to deduce that our problem has (AEG).     

基于贝叶斯学习的最优互联网化房地产金融合约

房地产金融的互联网化是当前金融市场创新的重要方向。本文采用动态道德风险理论研究了互联网化房地产金融合约的最优性及其经济特征,并以动态合约的视角考虑了参与方的贝叶斯学习对互联网化房地产金融最优性的影响。研究发现,为了激励资信良好的融资方努力工作且排除资信欠佳的融资方,互联网化房地产金融合约不仅需权衡激励成本和收益以确定适当的努力激励强度,而且还需考虑因融资方的信息优势带来的信息租金。     

Recognition of beer brand based on multivariate analysis of volatile fingerprint

Automated head-space solid-phase microextraction (HS-SPME)-based sampling procedure, coupled to gas chromatography–time-of-flight mass spectrometry (GC–TOFMS), was developed and employed for obtaining of fingerprints (GC profiles) of beer volatiles. In total, 265 speciality beer samples were collected over a 1-year period with the aim to distinguish, based on analytical (profiling) data, (i) the beers labelled as Rochefort 8; (ii) a group consisting of Rochefort 6, 8, 10 beers; and (iii) Trappist beers. For the chemometric evaluation of the data, partial least squares discriminant analysis (PLS-DA), linear discriminant analysis (LDA), and artificial neural networks with multilayer perceptrons (ANN-MLP) were tested. The best prediction ability was obtained for the model that distinguished a group of Rochefort 6, 8, 10 beers from the rest of beers. In this case, all chemometric tools employed provided 100% correct classification. Slightly worse prediction abilities were achieved for the models “Trappist vs. non-Trappist beers” with the values of 93.9% (PLS-DA), 91.9% (LDA) and 97.0% (ANN-MLP) and “Rochefort 8 vs. the rest” with the values of 87.9% (PLS-DA) and 84.8% (LDA) and 93.9% (ANN-MLP). In addition to chromatographic profiling, also the potential of direct coupling of SPME (extraction/pre-concentration device) with high-resolution TOFMS employing a direct analysis in real time (DART) ion source has been demonstrated as a challenging profiling approach.