二维均匀流作用的线性表面张力-重力短峰波解析解

考虑二维均匀流的作用,寻找到有限水深线性表面张力-重力短峰波系统的解析解.进而从中发现广义Doppler频移关系和广义色散关系.而且,广义本征频率直接与均匀流相关,具有对偶值,富于变化性. 关键词： 表面张力-重力短峰波 二维均匀流 广义Doppler频移关系 广义色散关系     

Local aromaticity in polycyclic aromatic hydrocarbons: electron delocalization versus magnetic indices

The local aromaticity of benzenoid rings is examined by means of the Polansky index (P) and generalized population analysis (GPA). The results are found to agree very well with recently published circuit-condensed ring currents and magnetic-energetic aromaticity indices, but no correlation is found with nucleus independent chemical shifts (NICS). This is usually seen as a manifestation of the more general multidimensional nature of aromaticity. This paper examines the sources for the observed correlations, showing that some indices give conflicting results because they inherently reflect different phenomena.     

基于模糊理论的汽轮机故障诊断

针对汽轮发电机组的单一故障诊断的局限性,对现有的故障进行分析和比较.根据振动信号的基本原理,应用了综合模糊诊断的方法对汽轮机的六种常见故障进行诊断.首先由不同故障在不同特征倍频的比例关系得到故障的模糊矩阵,分段对故障振动信号求隶属度,再与故障的模糊矩阵相乘即可求出各故障的隶属度,并用Minkowski距离公式计算隶属度距离大小,来判断诊断的准确性;最后提出模糊诊断的前景及存在的问题.     

Energy and momentum of general spherically symmetric frames on the regularizing teleparallelism

In the context of the covariant teleparallel framework, we use the 2-form translational momentum to compute the total energy of two general spherically symmetric frames. The first one is characterized by an arbitrary function H(r), which preserves the spherical symmetry and reproduces all the previous solutions, while the other one is characterized by a parameter ξ which ensures the vanishing of the axial of trace of the torsion. We calculate the total energy by using two procedures, i.e., when the Weitzenböck connection Γ_α^β is trivial, and show how H(r) and ξ play the role of an inertia that leads the total energy to be unphysical. Therefore, we take into account Γ_α^β and show that although the space×we use contain an arbitrary function and one parameter, they have no effect on the form of the total energy and momentum as it should be.     

Wind turbine fault detection using multiwavelet denoising with the data-driven block threshold

Rapid expansion of wind turbines has drawn attention to reduce the operation and maintenance costs. Continuous condition monitoring of wind turbines allows for early detection of the generator faults, facilitating a proactive response, minimizing downtime and maximizing productivity. However, the weak features of incipient faults in wind turbines are always immersed in noises of the equipment and the environment. Wavelet denoising is a useful tool for incipient fault detection and its effect mainly depends on the feature separation and the noise elimination. Multiwavelets have two or more multiscaling functions and multiwavelet functions. They possess the properties of orthogonality, symmetry, compact support and high vanishing moments simultaneously. The data-driven block threshold selected the optimal block length and threshold at different decomposition levels by using the minimum Stein’s unbiased risk estimate. A multiwavelet denoising technique with the data-driven block threshold was proposed in this paper. The simulation experiment and the feature detection of a rolling bearing with a slight inner race defect indicated that the proposed method successfully detected the weak features of incipient faults.     

利用可调谐的混沌Fabry-Perot激光器实现波分复用无源光网络的断点检测

波分复用无源光网络具有支路多、节点密的特征,为精确定位各支路的断点,提出了一种基于可调谐混沌Fabry-Perot激光器的检测方法.将光反馈多纵模Fabry-Perot半导体激光器作为混沌光源,在改变反馈光光波模式的条件下输出波长可调谐的混沌激光.以探测光的波长标记各被测支路,将探测信号和携带延时信息的回波信号进行互相关运算,根据相关曲线峰值的位置即可完成定位.分析了可调谐混沌源的特性,并以1×4的波分复用无源光网络为例,进行了初步的实验验证,结果表明该方法可以精确定位光网络支路中连接点及断点的位置,空间分辨率达4 cm,且与探测距离无关.     

Probing the fourth neutrino existence by neutral current oscillometry in the spherical gaseous TPC

It is shown that, if the “new neutrino” implied by the Reactor Antineutrino Anomaly exists and is in fact characterized by the suggested relatively high mass squared difference and reasonably large mixing angle, it should clearly reveal itself in the oscillometry measurements. For a judicious neutrino source the “new oscillation length” L₁₄ is expected shorter than 1.5 m. Thus the needed measurements can be implemented with a gaseous spherical TPC of modest dimensions with a very good energy and position resolution, detecting nuclear recoils following the coherent neutrino-nucleus elastic scattering. The best candidates for oscillometry, yielding both monochromatic neutrinos as well as antineutrinos, are discussed. A sensitivity in the mixing angle θ₁₄, sin²(2θ₁₄)=0.1 (99%), can be reached after a few months of data handling.     

Single domain wall dynamics in ferromagnetic lamination with variable conductivity

The influence of variable conductivity and thickness of two outer non-ferromagnetic layers on magnetization reversal of one central ferromagnetic layer is theoretically investigated. The model of a thin rigid 180°$180°$ domain wall moving transversely through the axially magnetized ferromagnetic layer is used to calculate induced eddy currents in lamination from which the domain wall mobility is determined. The effect of asymmetric distribution of eddy currents around moving domain wall results in acceleration of the wall near the edge of the lamination. The known domain wall mobility in ferromagnetic lamination can then be used to determine either the conductivity or the thickness of deposited outer non-ferromagnetic layers as proposed in discussion.