A note on the measurement of phase space observables with an eight-port homodyne detector

It is well known that the Husimi Q-function of the signal field can actually be measured by the eight-port homodyne detection technique, provided that the reference beam (used for homodyne detection) is a very strong coherent field so that it can be treated classically [see e.g. Leonhardt, U.; Paul, H. Phys. Rev. A 1993, 47, R2460–R2463]. Using recent rigorous results on the quantum theory of homodyne detection observables [Kiukas, J.; Lahti, P. J. Mod. Opt., in press (see arXiv:0706.4436v1 [quant-ph])], we show that any phase space observable, and not only the Q-function, can be obtained as a high amplitude limit of the signal observable actually measured by an eight-port homodyne detector. The proof of this fact does not involve any classicality assumption.     

基于相空间方法的海底底质分类

基于相空间重构方法,从海底回波信号的相平面和相空间中提取了三个特征量:一阶距、相似序列重复度和熵,应用于海底底质分类。通过对海上实验数据的分析表明:这三个特征参数能有效地将两类海底分开,结果与海底采样分析吻合良好。     

相空间重构延迟时间互信息改进算法研究

针对改进互信息算法利于快速可靠获得时间序列相空间重构的延迟时间问题,通过等边缘分布2、4等分Lorenz时间序列构成平面分析Cellucci互信息算法缺陷;用大小顺序值代替原序列数值、判断新序列数值所在等边缘概率区间获得概率分布矩阵、修正概率分布矩阵最末行与列改进Cellucci互信息算法;以改进算法所得最佳延迟时间进行Lorenz时间序列相空间重构并以小数据量法得出其最大Lyapunov指数,对比雅可比矩阵法所得最大Lyapunov指数以确认改进算法的有效性。结果表明,时间序列长度不能整除划分区间数时Cellucci互信息算法会获得错误的最佳延迟时间;所提改进算法能消除Cellucci算法缺陷,且计算速度快于Fraser算法;数据序列长度较大时改进算法结果更稳定;由两种最大Lyapunov指数计算方法所得结果间误差较小,表明改进的互信息算法有效、可靠。     

基于Gram-Charlier展开的相空间重构时间延迟选择方法

时间延迟是相空间重构中的一个关键参数。利用冗余度作为标准来选择时间延迟具备充分的理论依据,然而冗余度的计算在实现上比较困难。基于概率密度的G ram-Charlier展开式,提出了一种简化的计算方法,该方法显著降低了冗余度计算的复杂度,使得冗余度方法能够有效地应用于相空间重构时间延迟的选择。     

He II phase separaton with slits and porous plugs for space cryogenics

Superfluid helium (He II) is an excellent coolant for space instruments like infrared detectors which need temperatures down to 2 K A He II phase separator is a crucial part of the cryogenic system at zero-gravity: it keeps the liquid phase separated from the vapour, by using the fountain effect in narrow flow channels between the He II storage under a heat load and the (cooler) vent line pumped by the space vacuum. The boil-off gas is used as a heat intercept and leaves the system at the ambient temperature which is close to 300 K on the Space Shuttle. A number of research groups are now in the middle of investigations of so called porous plugs as phase separators which are fine pore sinter bodies of cm dimensions.This paper compares and discusses the different research efforts and tries to unify seemingly contradictory results within a simple theory deduced from the phase separating properties of single straight slits. According to the two-fluid model including Gorter-Mellink friction, the flow properties depend strongly on the internal geometry, which makes quantitative predictions for porous plugs difficult.Suggestions are made with regard to room temperature measurements of permeability, effective porosity and the like and with regard to a low temperature experimental programme.     

改进相空间重构方法在混沌识别中的应用研究

讨论了传统非线性时间序列相空间重构方法的特点。提出了一种改进的相空间重构方法．为了揭示非线性时间序列中的非线性相关性。采用了一种基于关联积分的统计量，并研究了不同参数对它的影响．研究了延迟时间和嵌入维数之间的关系，并采用时间窗口描述这2个参数的变化规律．同时，应用改进方法计算了混沌时间序列的重构参数。重构了混沌信号的吸引子．研究结果表明。该方法能够从时间序列有效地重构原系统的相空间，为混沌信号识别提供了新的途径．     

Analysing bullwhip and backlash effects in supply chains with phase space trajectories

We will investigate demand and supply variations in supply chains commonly known as bullwhip and backlash effects. The main goal of this paper is to detect bullwhip and backlash effects and its interactions by measuring only a few supply chain variables. To do so, we consider a multistage supply chain and analyse it with the aid of phase space trajectories. An examination of the geometrical structures of trajectories can reveal the dynamics of the bullwhip and backlash behaviour in supply chains. Therefore, we use a physical analogy to wave theory and describe order and delivery oscillations as a process of wave reflection. The proposed methodology systematically provides the basis for analysing a number of dynamic and transient behaviours that supplement the traditional analysis. These behaviour patterns include supply chain stability, compactness and bullwhip/backlash trade-offs, which have important consequences for the design, operation and control of supply chains.     

嵌入式相电检测及相序调整系统设计

针对许多行业有三相电相序与安全生产的要求,设计了基于32位ARM9处理器芯片S3C2410X的嵌入式系统,并移植了Linux操作系统来提高系统多任务与实时响应能力.介绍了该系统各硬件模块设计和软件设计流程,硬件模块由相电检测、相序调整、人机交互及TC35i报警等模块构成.该系统可对"三相四线制"供电端口进行相电检测与相序调整,在出现异常时执行报警操作并短信或者电话通知到负责人员,可应用于压缩机、风机和三相电机等装置的供电,特别适用于大型的移动供配电设备.     

水下目标辐射噪声相空间重构参数选取方法

利用自相关函数法和平均互信息法求取相空间重构的延迟参数,对实测数据计算结果进行了分析比较,确定了相空间重构时间延迟参数的选择方法。在用伪最近邻法进行相空间重构嵌入维数的选取时,使用时空曲线法计算TheilerWindow的窗口值W,并以此为依据剔除由于时间上的邻近而造成的空间上的邻近的最近邻点,改进了伪最近邻计算嵌入维数的方法。实测数据计算结果表明,该方法能够获取合理、有效的嵌入维参数。     

Online prediction of dense medium suspension density based on phase space reconstruction

In the dense medium separation process of the coal preparation plant, the fluctuation of raw coal quality and the lag of heavy media separation density adjustment often lead to the instability of clean coal quality. To solve this problem, phase space reconstruction with online data was carried out to derive a mathematical formula of working dense medium density with raw coal ash and clean coal ash produced. Then the data was trained by two ways, namely Least Square Support Vector Machine (LS-SVM) and LS-SVM based on time series. Simulation results show that the latter way can achieve a more accurate prediction of heavy medium suspension density.     

A mesoporous silica modified conjugated polymer film: Preparation and detection nitroaromatics in aqueous phase

The linear conjugated polymer of polyfluorene/poly(p-phenylenevinylenes) (PFO/PPV) was synthesized and selected as the matrix film. The incorporation of a small fraction of inorganic mesoporous silicas into the polymer matrix resulted in a significant increase in overall detection efficiency of nitroaromatics. The structure of the obtained mixed films was characterized by ¹H-NMR, IR, and XRD. The optical and fluorescence properties of the mixed films were demonstrated by ultraviolet and visible spectroscopy (UV-Vis) and photoluminescence (PL) spectra in ethanol/water solution. Compared with the pure conjugated polymer film, the mixed films had high fluorescence quenching sensitivity toward nitroaromatic compounds, especially 2,4,6-trinitrophenol (TNP), in the aqueous phase. The fluorescent emission quenching is quantitative and can be analyzed on the basis of the Stern-Volmer model relation with the quenching process. The results revealed that such mixed matrix films of conjugated polymer/mesoporous silicas can be a promising strategy of designing chemosensory materials for detecting nitroaromatic compounds.     

空间引力波探测望远镜多自由度形变测量方法解耦研究与噪声分析

空间引力波探测望远镜是引力波探测卫星的核心载荷之一,它同时对传输光束进行扩束和缩束。光程稳定性是望远镜的核心指标之一,其与望远镜结构稳定性密切相关。为了满足引力波探测任务对望远镜提出的超高光程稳定性和结构稳定性要求,必须对望远镜结构形变测量进行研究。本文开展了对空间引力波探测望远镜多自由度形变测量的研究,重点解决多自由度测量的耦合问题,并对误差来源进行详细分析。在空间引力波探测望远镜的研制阶段,该测量方法的研究有望满足望远镜多自由度形变测量的需求,为望远镜设计提供多自由度形变的数据反馈,为望远镜光程稳定性研究提供指导。

     

Fault detection,classification, and location for active distribution network based on neural network and phase angle analysis

The improved radial basis function (RBF) method utilizes an orthogonal regression matrix to produce an artificial neural network structure based on regularized least square. The phase angle and amplitude signal of fault voltage and current are extracted based on frequency domain analysis. The proposed method adopts the fault signal for fault diagnosis synchronously. The IEEE 13-bus active distribution network (ADN) simulation model is set up in Matlab. Test results demonstrate that accuracy of the fault diagnosis can reach 98.07% and the response time of the fault classification method is less than 0.04s. The wavelet neural network (WNN) model is developed to extract the maximum decomposition level and time series behavior. The WNN method can resist noise effects and improve the fault classification accuracy by 4.3%. The effect of fault type and fault resistance on the fault location method is researched. The fault simulation result shows that the proposed method can locate a fault precisely and synchronously. The improved RBF method can diagnose the fault section, classify the fault type and locate a fault accurately in ADN. The research is significant to maintain system stability against realistic fault and network restore.