P—type AlAs／[GaAs／AlAs]Semiconductor／Superlattice DBR Grown by MBE

A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n +-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm 2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×10 18 cm -3 ). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.     

Shape-based time series similarity measure and pattern discovery algorithm

Pattern discovery from time series is of fundamental importance. Most of the algorithms of pattern discovery in time series capture the values of time series based on some kinds of similarity measures. Affected by the scale and baseline, value-based methods bring about problem when the objective is to capture the shape. Thus, a similarity measure based on shape, Sh measure, is originally proposed, and the properties of this similarity and corresponding proofs are given. Then a time series shape pattern discovery algorithm based on Sh measure is put forward. The proposed algorithm is terminated in finite iteration with given computational and storage complexity. Finally the experiments on synthetic datasets and sunspot datasets demonstrate that the time series shape pattern algorithm is valid.     

Self-adaptive Processing and Forecasting Algorithm for Univariate Linear Time Series

As the Box-Jenkins method could not grasp the non-stationary characteristics of time series exactly, nor identify the optimal forecasting model order quickly and precisely, a self-adaptive processing and forecasting algorithm for univariate linear time series is proposed. A self-adaptive series characteristic test framework which employs varieties of statistic tests is constructed to solve the problem of inaccurate identification and inadequate processing for non-stationary characteristics of time series. To achieve favorable forecasts, an optimal forecasting model building algorithm combined with model filter and candidate model pool is proposed, in which a univariate linear time series forecasting model is built. Experimental data demonstrates that the proposed algorithm outperforms the comparativemethod in all forecasting performance statistics.     

THE INVERSE ELECTROMAGNETIC SCATTERING OF INHOMOGENEOUS DIELECTRIC THIN TUBES

By using the method of Fourier series expansion, the inverse electromagnetic scattering problemof a 2- dimensional lossy dielectric body, of which the cross section is a narrow annulus, is studied. Theanalytic expressions of the electric parameters of a dielectric body are given in terms of the outsidesca,ttering field, and the simulative results are satisfactory.     

Impossible Differential Evaluations for New-Structure Series

Impossible differential cryptanalysis is a powerful tool to evaluate the strength of a block cipher structure, and the key step of this cryptanalysis is to find the longest impossible differential. Recently a series of generalized Feistel structures named New-structure I, II, III and IV were proposed, which were designed with full consideration of differential and linear cryptanalysis secu- rity. In this paper, we investigate the impossible differen- tial properties of New-structure series, and we show that there always exists 14/∞/19/15 rounds impossible differ- ential for New-structure I, II, III and IV respectively.     

Effects of the Planar Optical Waveguide Thickness on the Transmission Attenuation^①

By analyzing and computing,according to the wave theory of planar optical waveguide attenuation,a new opinion is put forward.A series of transmission atteenuation with waveguide film-thickness are given and it illustrates that optical transmission is not carrying out efficiently within some waveguide film-thickness.     

基于Y和Z参数表征的微波SiGe HBT小信号模型参数提取

High frequency intrinsic small-signal model parameter extraction for microwave SiGe heterojunction bipolar transistors is studied, with a focus on the main feedback elements including the emitter series resistor, internal and external base-collector capacitors as well as the base series resistor, all of which are important in determining the behavior of the device equivalent circuit. In accordance with the respective features of definition of the Y- and Z-parameters, a novel combined use of them succeeds in reasonably simplifying the device equivalent circuit and thus decoupling the extraction of base-collector capacitances from other model parameters. As a result, a very simple direct extraction method is proposed. The proposed method is applied for determining the SiGe HBT small-signal model parameters by taking numerically simulated Y- and Z-parameters as nominal ＂measurement data＂ with the help of a Taurus-device simulator. The validity of the method is preliminarily confirmed by the observation of certain linear relations of device frequency behavior as predicted by the corresponding theoretical analysis. Furthermore, the extraction results can be used to reasonably account for the dependence of the extracted model parameters on device geometry and process parameters, reflecting the explicit physical meanings of parameters, and especially revealing the distributed nature of the base series resistor and its complex interactions with base-collector capacitors. Finally, the accuracy of our model parameter extraction method is further validated by comparing the modeled and simulated S-parameters as a function of frequency.     

Superposition Effect of Passive Intermodulation for Cable Assemblies with Discrete Point-Sources

In order to expand the cell coverage of wireless cellular systems, the number of passive components in wireless systems has been substantially increased. There can be many passive intermodulation(PIM) pointsources even in a device or a radio link, which may add up constructively or destructively. A modified point-source model with lossy components is proposed to evaluate the superposition effect of the forward and refl ected PIM in case of series connection. The index of the series connection factor(SCF) is employed for systems that incorporate multiple PIM sources to predict the important characteristics of the cumulative PIM, such as the maximum and minimum values and the limit form. Furthermore, some initial experimental results are given out and the deviation in the above-mentioned prediction is also analyzed.     

CIRCULARLY POLARIZED CONTOURED BEAM ANTENNA WITH OFFSET REFLECTORARRAY FEEDS

A mathematical model of the circularly polarized feed is developed in this paper.The approach,for the Jacobi-Bessel series expansion of the physical optics radiation integral studied by R.Mittraet al.is extended to the case of circular polarizition.A computation method for the circularly polar-ized contoured beam of the offset reflector antennas is analysed.Representative numerical resultis given for effective isotropic radiated power contour-plot of the western zone coverage of Chineseterritory by the 7-element array illumination.     

A novel direction of arrival estimator

A Direction Of Arrival(DOA) estimator based on the signal separation principle is introduced, and one of representative multidimensional estimators is established by introducing Matrix Operator projection signal steering Vector Excision(MOVE) operation. Thanks to Alternating Separation (AS) technique, the multidimensional problem is transformed into a series of one-dimensional optimal ones. Furthermore, an equivalent simplified implementation of the AS is obtained. Finally the definiteness and uniqueness of the estimator are analyzed.     

A Novel Parallel Scheme for Fast Similarity Search in Large Time Series

The similarity search is one of the fundamental components in time series data mining,e.g.clustering,classification,association rules mining.Many methods have been proposed to measure the similarity between time series,including Euclidean distance,Manhattan distance,and dynamic time warping(DTW).In contrast,DTW has been suggested to allow more robust similarity measure and be able to find the optimal alignment in time series.However,due to its quadratic time and space complexity,DTW is not suitable for large time series datasets.Many improving algorithms have been proposed for DTW search in large databases,such as approximate search or exact indexed search.Unlike the previous modified algorithm,this paper presents a novel parallel scheme for fast similarity search based on DTW,which is called MRDTW(MapRedcuebased DTW).The experimental results show that our approach not only retained the original accuracy as DTW,but also greatly improved the efficiency of similarity measure in large time series.     

THE METHOD OF SEPARATING HARMONIC SIGNALS FROM MULTIPLICATIVE AND ADDITIVE NOISES

This paper focuses on the extraction of a harmonic signal from multiplicative and additive noises. A method is proposed in two stages: (1) to square the original discrete time series, which in- cludes both signals and noises, and form a new time series. By this means, the multiplicative noise is converted to additive noise; and (2) to filter out the noise by using existing noise removal schemes. With a large amount of simulation, experimental results demonstrated the efficiency and effective- ness of this newly developed method in terms of Signal-to-Noise Ratio (SNR) and other criteria. From the experiment, it is also found that: the two kinds of noises affect the SNR differently. In gen- eral, the SNR is not influenced by multiplicative Gaussian noise regardless of its variance. However, if both kinds of noise exist, the SNR decreases with the incensement of the Variance of Additive Noise to Multiplicative Noise Ratio (VAMNR). This analysis is also supported by simulation work.     

An Efficient Adaptive Failure Detection Mechanism for Cloud Platform Based on Volterra Series

Failure detection module is one of important components in fault-tolerant distributed systems, especially cloud platform. However, to achieve fast and accurate detection of failure becomes more and more difficult especially when network and other resources＇ status keep changing. This study presented an efficient adaptive failure detection mechanism based on volterra series, which can use a small amount of data for predicting. The mechanism uses a volterra filter for time series prediction and a decision tree for decision making. Major contributions are applying volterra filter in cloud failure prediction, and introducing a user factor for different QoS requirements in different modules and levels of IaaS. Detailed implementation is proposed, and an evaluation is performed in Beijing and Guangzhou experiment environment.     

Social network users clustering based on multivariate time series of emotional behavior

It is known that the social network is an excellent source for gathering the emotions of people. There are thousands of micro-blogs posted in every second and every micro-blog that may contain a variety of user＇s emotions. The users＇ collective emotional behaviors are with great impacts on today＇s societies, so it is good to find groups for society management based on users＇ emotional behavior. This article focuses on analyzing multivariate emotional behavior of users in social network and the goal is to cluster the users from a fully new perspective-emotions. The following tasks are completed： firstly, the multivariate emotion of Chinese micro-blog with vector is analyzed, and multivariate time series to describe the user＇s emotional behavior are constructed. Seconedly, considering principal component analysis （PCA） in similarity and distance similarity, the similarity of the multivariate emotion time series is measured. The contribution could be summarized as follows： groups of users though different emotions in social network are discovered. The emotional fluctuation and intensity of users are considered as well. Experiment in clustering effectively illustrates the emotional behavior characteristics of the Users in different groups.     

DESIGN AND MANUFACTURE OF A 1GHz SPLIT RING RESONATOR

The Q value and the resonant frequency for split ring resonator are derived by the method of equivalentcircuit.The relationship between Q and dimensions of split ring resonator is obtained by taking theresonator as a solenoid.A series of curves for optimum design is plotted.In our experiments,a high Q value of 900 to 1000 in the frequency range of 1 to 1.4 GHz is easilyobtained;the resonator has the merits of small dimension,wide frequency range and simplicity inconstruction.     

A cross-reference method of parameter estimation and noise reduction and its applications

This paper proposes a cross-reference method of nonlinear time series analysis, combining the tasks of dynamical system parameter estimation and noise reduction which were fulfilled separately before. With the positive interaction between the two processing modules, the method is somewhat superior. Some prior works can be viewed as special cases of this general framework and effective new algorithms may be devised according to it. Two examples of chaotic time series analysis are also given to show the applicability of the proposed method.     

Cloud Computing （3）

Editor's Desk: In the preceding two parts of this series, several aspects of cloud computing-including definition, classification, characteristics, typical applications, and service levels-were discussed. This part continues with a discussion of Cloud Computing Oopen Architecture and Market-Oriented Cloud. A comparison is made between cloud computing and other distributed computing technologies, and Google's cloud platform is analyzed to determine how distributed computing is implemented in its particular model.     

SELECTION OF PROPER EMBEDDING DIMENSION IN PHASE SPACE RECONSTRUCTION OF SPEECH SIGNALS

In phase space reconstruction of time series, the selection of embedding dimension is important. Based on the idea of checking the behavior of near neighbors in the reconstruction dimension, a new method to determine proper minimum embedding dimension is constructed. This method has a sound theoretical basis and can lead to good result. It can indicate the noise level in the data to be reconstructed, and estimate the reconstruction quality. It is applied to speech signal reconstruction and the generic embedding dimension of speech signals is deduced.     

ANALYSIS OF THE CAPACITANCE OF RECTANGULAR SHIELDED LINE WITH OFFSET INNER CONDUCTOR

The partial charge-simulation method is presented for calculating the capacitances of rectangularshielded lines with offset inner conductors.The capacitances calculated by using this method are in goodagreement with those of other available methods.This method can improve the accuracy by increasing theterm number N of series.     

A Cascade Multilevel Inverter Using a Single DC Source

3. SWITCHING ANGLES If the nominal capacitor voltage is chosen as Vdc/2, then one can compute the switching angles θ1, θ 2, and θ 3. Following the development, the Fourier series expansion of the （staircase） output voltage waveform of the multilevel inverter as shown in Fig. 2（a） is