关于一维可压Navier-Stokes方程自模解的注记

目的研究一维可压的Navier-Stokes方程的自模解的非存在性。方法利用能量爆破理论。结果当压力函数p(ρ)=aργ(γ>1)的时候,方程没有具有有限能量的自模解。结论可压的Navier-Stokes方程的自模解不能用来构造满足有限能量的奇异解。

黏性系数依赖于密度的一维可压Navier-Stokes方程的自模解

目的为研究黏性系数依赖于密度的一维可压Navier-Stokes方程自模解的非存在性问题。方法对能量函数进行定量分析。结果证明了黏性系数依赖于密度的一维可压Navier-Stokes方程不存在具有有限总能量的自模解。结论将研究常黏性系数Navier-Stokes方程的自模解的方法推广到黏性系数依赖于密度的情形。

关于二维等温可压缩球对称Navier-Stokes方程自模解的注记

研究了二维等温可压缩球对称Navier-Stokes方程的自模解,给出了具有有限能量的Navier-Stokes方程既没有向前的自模解,也没有向后的自模解的充分条件.

一维可压Navier-Stokes方程自由边值问题的自模解

研究黏性系数μ(ρ)=1+θρθ时一维可压Navier-Stokes方程自模解的非存在性.首先通过建立能量估计式,熵估计式得到密度函数ρ的正的下界,然后对能量函数进行定量分析,利用能量爆破理论证明了θ>0时一维可压Navier-Stokes方程不存在具有有限总能量的自模解.最后将常黏性系数Navier-Stokes方程自模解的方法推广到黏性系数依赖于密度的情形,并且把θ的范围扩展到θ>0.

Joint application of feature extraction based on EMD-AR strategy and multi-class classifier based on LS-SVM in EMG motion classification

This paper presents an effective and efficient combination of feature extraction and multi-class classifier for motion classification by analyzing the surface electromyografic(sEMG) signals. In contrast to the existing methods,considering the non-stationary and nonlinear characteristics of EMG signals,to get the more separable feature set,we introduce the empirical mode decomposition(EMD) to decompose the original EMG signals into several intrinsic mode functions(IMFs) and then compute the coefficients of autoregressive models of each IMF to form the feature set. Based on the least squares support vector machines(LS-SVMs) ,the multi-class classifier is designed and constructed to classify various motions. The results of contrastive experiments showed that the accuracy of motion recognition is improved with the described classification scheme. Furthermore,compared with other classifiers using different features,the excellent performance indicated the potential of the SVM techniques embedding the EMD-AR kernel in motion classification.

A test sequence generation method of zone controller based on timed automata

In order to solve the problem of artificial generation and low efficiency of test sequences for zone controller (ZC), a model-based automatic generation method of test sequence is proposed. Firstly, the timed automata model is established based on function analysis of the zone controller, and the correctness of the model is verified by UPPAAL. Then by parsing the timed automata model files, state information and transition conditions can be extracted to generate test case sets. Finally, according to the serialization conditions of test cases, the test cases are serialized into test sequences by using the improved depth first search algorithm. A case, the ZC controls the train running within its jurisdiction, shows that the method is correct and can effectively improve the efficiency of test sequence generation.

Analytical modelling and free vibration analysis of piezoelectric bimorphs

An efficient and accurate analytical model for piezoelectric bimorph based on the improved first-order shear deformation theory （FSDT） is developed in this work. The model combines the equivalent single-layer approach for mechanical displacements and a layerwise-type modelling of the electric potential. Particular attention is devoted to the boundary conditions on the outside faces and to the interface continuity conditions of the bimorphs for the electromechanical variables. Shear correction factor （k） is introduced to modilfy both the shear stress and the electric displacement of each layer. And the detailed mathematical derivations are presented. Free vibration problem of simply supported piezoelectric bimorphs with series or parallel arrangement is investigated for the closed circuit condition, and the results for different length-to-thickness ratios are compared with those obtained from the exact 2D solution. Excellent agreements between the present model prediction with k=-8/9 and the exact solutions are observed for the resonant frequencies.

Solutions to a Novel Casimir Equation for the Ito System

We discuss two classes of solutions to a novel Casimir equation associated with the Ito system,a couplednonlinear wave equation.Both travelling wave solutions and separable self-similar solutions are discussed.In a numberof cases,explicit exact solutions are found.Such results,particularly the exact solutions,are useful in that they provideus a baseline of comparison to any numerical simulations.Besides,such solutions provide us a glimpse of the behaviorof the Ito system,and hence the behavior of a type of nonlinear wave equation,for certain parameter regimes.

Removal of noises from electromagnetic radiation of coal or rock with EEMD-adaptive morphological filter

The electromagnetic radiation （EMR） signal collected by monitoring system during coal or rock dynamic disaster may be interferred easily by electromagnetic noises in mines. The noises have a direct influence on the recognition and analysis of the EMR signal features during the disaster. With the aim of removing these noises, an ensemble empirical mode decomposition （EEMD） adaptive morphological filter was proposed. From the result of the simulation and the experiment, it is shown that the method can restrain the random noise and white Gaussian noise mixed with EMR signal effectively. The filter is highly useful for improving the robustness of the coal or rock dynamic disaster monitoring system.

Automatic target recognition of moving target based on empirical mode decomposition and genetic algorithm support vector machine

In order to improve measurement accuracy of moving target signals, an automatic target recognition model of moving target signals was established based on empirical mode decomposition(EMD) and support vector machine(SVM). Automatic target recognition process on the nonlinear and non-stationary of Doppler signals of military target by using automatic target recognition model can be expressed as follows. Firstly, the nonlinearity and non-stationary of Doppler signals were decomposed into a set of intrinsic mode functions(IMFs) using EMD. After the Hilbert transform of IMF, the energy ratio of each IMF to the total IMFs can be extracted as the features of military target. Then, the SVM was trained through using the energy ratio to classify the military targets, and genetic algorithm(GA) was used to optimize SVM parameters in the solution space. The experimental results show that this algorithm can achieve the recognition accuracies of 86.15%, 87.93%, and 82.28% for tank, vehicle and soldier, respectively.

Fault Diagnosis of Reciprocating Compressors Valve Based on Cyclostationary Method

The relationship between second-order cyclostationary method and time-frequency distribution is studied, and cyclic autocorrelation（CA） function is indicated to be one sort of special time-frequency distribution method. Furthermore, a fault diagnosis method for reciprocating compressors based on empirical mode decomposition （EMD） and CA function is proposed, and then it is applied to the fault diagnosis of reciprocating compressor valve. Firstly, the vibration signal of reciprocating compressor valve is decomposed by using ENID method, and several intrinsic mode functions （IMFs） are obtained. Secondly, the IMFs are evaluated by some denoising criterions to remove the noise and interfering ones. Finally, the CA functions of the remained IMFs are calculated, which will be used to reconstruct the CA function of the original vibration signal. Engineering application indicates that this method can sufficiently inhibit the cross-interference items of CA function. Therefore, more explicit working conditions of reciprocating compressor components can be achieved.

Multi-loop Constrained Iterative Model Predictive Control Using ARX -PLS Decoupling Structure

A multi-loop constrained model predictive control scheme based on autoregressive exogenous-partial least squares(ARX-PLS) framework is proposed to tackle the high dimension, coupled and constraints problems in industry processes due to safety limitation, environmental regulations, consumer specifications and physical restriction. ARX-PLS decoupling character enables to turn the multivariable model predictive control(MPC) controller design in original space into the multi-loop single input single output(SISO) MPC controllers design in latent space.An idea of iterative method is applied to decouple the constraints latent variables in PLS framework and recursive least square is introduced to identify ARX-PLS model. This algorithm is applied to a non-square simulation system and a stirred reactor for ethylene polymerizations comparing with adaptive internal model control(IMC) method based on ARX-PLS framework. Its application has shown that this method outperforms adaptive IMC method based on ARX-PLS framework to some extent.

Effect of the computer fuzzy control on coal seam injection

To enhance the technology and efficiency of strata injection is a problem to be solved urgently. Because of effected by the rough and poor production conditions of mining and the changeable bearing condition of strata, the technological process of injection can not be controlled automatically.The fuzzy controlling technology of the coal strata injection is applied. This is the good way to ensure the effectiveness and efficiency of coal strata injection and to solve the current problems of production and safety in mining industry.

Joint detection method of pornographic images with skin-like color background

A novel approach is proposed to automatically detect pomographic images with skin-like color background on the Intemet using the locations of human faces and bodies. It has two separate skin-color detection steps： the first one is to quickly detect the potential human skin-color regions; and the second one is to use an off-the-shelf face detector to locate a human face and then apply hypothesis testing based on series of assumptions which take into account the face-height ratio, body orientation and modem photograph composition common sense, etc. After that, a template matching method is used to further discriminate normal images or pornographic ones. Experimental results show that the proposed method has high precision and real time speed.

Photocatalytic degradation of formaldehyde using mesoporous TiO_2 prepared by evaporation-induced self-assembly

The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.

Exact Generator and its High Order Expansions in Time-Convolutionless Generalized Master Equation:Applications to Spin-Boson Model and Exictation Energy Transfer

The time-convolutionless （TCL） quantum master equation provides a powerful tool to simulate reduced dynanfics of a quantum system coupled to a bath. The key quantity ill the TCL master equation is the so-called kernel or generator, which describes eflhcts of the bath degrees of freedom. Since the exact TCL generators are usually hard to calculate analytically, most applications of the TCL generalized master equation have relied on approximate generators using second and fourth order perturbative expansions. By using the hierarchical equation of motion （HEOM） and extended HEOM methods, we present a new approach to calculating the exact TCL generator and its high order perturbative expansions. The new approach is applied to the spin-boson model with diflhrent sets of parameters, to investigate the convergence of the high order expansiolls of the TCL generator. We also discuss circumstances where the exact TCL generator becomes singular for the spin-boson model, and a model of excitation energy transfer in the Fenna-Matthews-Olson complex.

Explaining How： The Intelligibility of Mechanical Explanations in Boyle

In this paper I examine the following claims by William Eaton in his monograph Boyle on Fire： （i） that Boyle＇s religious convictions led him to believe that the world was not completely explicable, and this shows that there is a shortcoming in the power of mechanical explanations; （ii） that mechanical explanations offer only sufficient, not necessary explanations, and this too was taken by Boyle to be a limit in the explanatory power of mechanical explanations; （iii） that the mature Boyle thought that there could be more intelligible explanatory models than mechanism; and （iv） that what Boyle says at any point in his career is incompatible with the statement of Maria Boas-Hall, i.e., that the mechanical hypothesis can explicate all natural phenomena. Since all four of these claims are part of Eaton＇s developmental argument, my rejection of them will not only show how the particular developmental story Eaton diagnoses is inaccurate, but will also explain what limits there actually are in Boyle＇s account of the intelligibility of mechanical explanations. My account will also show why important philosophers like Locke and Leibniz should be interested in Boyle＇s philosophical work.

Transmission Mechanisms of Monetary Policy in Saudi Arabia： Evidence From SVAR Analysis

In this research, the authors evaluate different channels of the monetary policy transmission mechanisms in Saudi Arabia over the last 15 years with a baseline of structural vector autoregressive （SVAR） models. Contemporaneous coefficient in the structural model indicates that while Saudi Arabia pegs its currency to US dollar, monetary policy instrument reacts positively to unexpected changes in the monetary aggregate. In addition to the traditional interest rate channel, the authors have also found the effects of credit channel. Moreover, variance decomposition results show that past shocks of credit, nominal effective exchange rate （NEER）, federal funds rate （FFR） and treasury bill （TB） are found to be important for credit growth in shorter and longer horizons. The exchange rate channel has been less significant in comparison to other channels.

Combustion of nitrate ester plasticized polyether propellants

Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism different from both double-base propellants and composite propellants.In order to study the combustion mechanism of NEPE propellants,we improved the free radical cracking model of previous research to make it capable of predicting the burning rate of NEPE propellants.To study the combustion characteristics and provide data support for the model,an experimental system was built and four kinds of NEPE propellants with different compositions and grain size distributions were tested.The results show that our modified model can reflect the combustion characteristics of NEPE propellants with an acceptable accuracy.The difference between the model and the experimental data is mainly caused by uncertain environmental factors and the ignorance of interactions between components.Both the experimental data and the results predicted by the model show that increasing the backpressure helps to increase the burning rate of NEPE propellants.Furthermore,the grain size of the oxidizer inside the NEPE propellant has a more severe impact on the burning rate but a lighter impact on the burning rate pressure exponent in comparison with the grain size of aluminum.For aluminum-free NEPE propellants,the reaction in the gas phase is dominant in the combustion process while adding aluminum into the propellant makes the solid phase dominant in the final stage.The combustion of fine aluminum particles near the burning surface generates heat feedback to the burning surface which evidently influences the surface temperature.However,the agglomeration of coarse aluminum particles has little effect on the burning surface temperature.

COMBINING SINGULAR SPECTRUM ANALYSIS AND PAR(p) STRUCTURES TO MODEL WIND SPEED TIME SERIES

Singular spectrum analysis （SSA） is a technique that decomposes a time series into a set of components, such as, trend, harmonics, and residuals. Leaving out the residual components and adding up the others, the time series can be smoothed. This procedure has been used to model Brazilian electricity consumption and flow series. The PAR（p）, periodic autoregressive models, has been broadly used in modelling energy series in Brazil. This paper presents an approach of this decomposition method, by fitting the PAR（p）, considering its multivariate version known as multivariate SSA （MSSA）. The method was applied to a vector of two wind speed series recorded at two locations in the Brazilian Northeast region. The obtained results, when compared to the univariate decomposition of each series, were far superior, showing that the spatial correlation between the two series were considered by MSSA decomposition stage.