Leak Detection in Water Distribution Systems Using Bayesian Theory and Fisher’s Law

A leak detection method based on Bayesian theory and Fisher’s law was developed for water distribution systems. A hydraulic model was associated with the parameters of leaks (location, extent). The randomness of parameter values was quantified by probability density function and updated by Bayesian theory. Values of the parameters were estimated based on Fisher’s law. The amount of leaks was estimated by back propagation neural network. Based on flow characteristics in water distribution systems, the location of leaks can be estimated. The effectiveness of the proposed method was illustrated by simulated leak data of node pressure head and flow rate of pipelines in a test pipe network, and the leaks were spotted accurately and renovated on time.     

The mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol

Fe (Ⅲ)-catalyzed ozonation yielded better degradation rate and extent of COD (Chemical Oxygen Demand) or oxalic acid as compared with oxidation by ozone alone. Two parameters with strong effects on the efficiency of ozonation are pH of the solution and the catalyst (Fe3 ) dosage. The existence of a critical pH value determining the catalysis of Fe (Ⅲ) in acid conditions was observed in phenol and oxalic acid systems. The best efficiency of catalysis was obtained at a moderate concentration of the catalyst. A reasonable mechanism of Fe (Ⅲ)-catalyzed ozonation of phenol was obtained based on the results and literature.     

基于自适应控制的非线性系统的滞后同步

Active control is an effective method for synchronizing two identical chaotic systems. However, this method works only for a certain class of chaotic systems with known parameters. An improvement method was proposed in order to overcome this limitation in this paper. A classical example was used to demonstrate the method. Finally, numerical examples were given to validate the efficiency of the method.     

Dynamical Behavior of Nonlinear Viscoelastic Timoshenko Beams with Damage on a Viscoelastic Foundation

Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams with large deflections, the nonlinear equations governing dynamical behavior of Timoshenko beams with damage on viscoelastic foundation were firstly derived. By using the Galerkin method in spatial domain, the nonlinear integro-partial differential equations were transformed into a set of integro-ordinary differential equations. The numerical methods in nonlinear dynamical systems, such as the phase-trajectory diagram, Poincare section and bifurcation figure, were used to solve the simplified systems of equations. It could be seen that simplified dynamical systems possess the plenty of nonlinear dynamical properties. The influence of load and material parameters on the dynamic behavior of nonlinear system were investigated in detail.     

Isobaric vapor-liquid equilibrium for methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system

This paper describes measurement of vapor-liquid equilibrium (VLE) data of methyldichlorosilane-methyltrichlorosilane-dimethyldichlorosilane system and that of the three binary systems at 101.325 kPa with a new pump-ebulliometer. The equilibrium composition of the vapor phase was calculated from pTx by indirect method. The model parameters of the liquid activity coefficient of the Wilson, NRTL, Margules and van Laar equations was corrected by the least square method. The ternary system VLE data were predicted by the Wilson equation, with the calculated boiling points showing good agreement with the experimental data.     

New multi-camera calibration algorithm based on 1D objects

A new calibration algorithm for multi-camera systems using 1D calibration objects is proposed. The algorithm integrates the rank-4 factorization with Zhang （2004）＇s method. The intrinsic parameters as well as the extrinsic parameters are recovered by capturing with cameras the 1D object＇s rotations around a fixed point. The algorithm is based on factorization of the scaled measurement matrix, the projective depth of which is estimated in an analytical equation instead ofa recursive form. For more than three points on a 1D object, the approach of our algorithm is to extend the scaled measurement matrix. The obtained parameters are finally refined through the maximum likelihood inference. Simulations and experiments with real images verify that the proposed technique achieves a good trade-off between the intrinsic and extrinsic camera parameters.     

Science Letters：Alterations in seedling vigour and antioxidant enzyme activities in Catharanthus roseus under seed priming with native diazotrophs

An experiment was conducted on Catharanthus roseus to study the effect of seed treatments with native diazotrophs on its seedling growth and antioxidant enzyme activities. The treatments had significant influence on various seedling parameters. There is no significant influence on dry matter production with the diazotrophs, Azospirillum and Azotobacter. However, the vital seedling parameters such as germination percentage and vigour index were improved. Azotobacter treatment influenced maximum of 50% germination, whereas Azospirillum and Azotobacter were on par with C. roseus with respect to their vigour index. There was significant difference in the population of total diazotrophs. Azospirillum and Azotobacter between rhizosphere and non-rhizosphere soils of C. roseus had the same trend and were observed at various locations of the study. The activities of antioxidant enzymes such as superoxide dismutase （SOD）, peroxidase （POX） and catalase （CAT） were increased to a significant extent due to the treatment with diazotrophs.     

Individualization of data-segment-related parameters for improvement of EEG signal classification in brain-computer interface

In electroencephalogram (EEG) modeling techniques, data segment selection is the first and still an important step. The influence of a set of data-segment-related parameters on feature extraction and classification in an EEG-based brain-computer interface (BCI) was studied. An auto search algorithm was developed to study four datasegment-related parameters in each trial of 12 subjects’ EEG. The length of data segment (LDS), the start position of data (SPD) segment, AR order, and number of trials (NT) were used to build the model. The study showed that, compared with the classification ratio (CR) without parameter selection, the CR was increased by 20% to 30% with proper selection of these data-segment-related parameters, and the optimum parameter values were subject-dependent. This suggests that the data-segment-related parameters should be individualized when building models for BCI.     

Effect of Air Velocity on Thermal Comfort under Thermal Environment Ramp Changing

Set points of the indoor air temperature and relative humidity in short-term staying location were studied. In this condition, the thermal reaction of human body varied with the ramp changes of the environmental thermal parameters. The change rules of about 60 subjects‘ thermal reaction to the ramp change of environment were surveyed, and the effect of air movement on the thermal reaction during transient condition was considered by using a questionnaire. With the experimental results and research findings under stable condition, a way to set environmental parameters of short-time staying location was recommended.     

Mathematical modeling and characteristics analysis for the nutation gear drive based on error parameters

We focused on the mathematical modeling and characteristics analysis for the nutation drive based on error parameters. The crown gear tooth profile equation was introduced according to the national standard double circular arc tooth profile and based on the equal tooth strength principle. The nutation drive meshing coordinate system was set up by introducing the cone vertex error, tilt error, nutation angle error and spiral angle error. The tooth profile equations of the double circular arc external and internal spiral bevel gears were further obtained based on the crown gear tooth profile equation concerning above mentioned error parameters. The influences of the nutation gear reducer tooth contact conditions were analyzed with the gear tilt error and axial misalignment error. Finally, the correctness of the theoretical analysis was verified by the contact spot test.     

孤子与湍流之间的相变

运用线性稳定性分析法严格证明，某些微扰KdV方程的孤子解具有条件稳定性。稳定条件被得到为系统参数与初始常数间的一个关系。在该条件下，微扰作用下的孤子解处于临界稳定态，湍流产生于临界态附近的混饨区、选择适当的系统参数与初始条件以满足稳定性条件，可以控制孤子与湍流之间的相变。     

Riemann-Liouville分数阶非线性系统的稳定性分析

通过讨论Riemann-Liouville分数阶非线性系统的稳定性,特别地分析了扰动系统的稳定性。基于分数阶线性微分方程的稳定性理论,利用拉普拉斯变换、Mittag-Leffler 函数和Gronwall不等式,给出了一些稳定性定理。     

Singular perturbation of a second-order three-point boundary value problem for nonlinear systems

This paper deals with the existence of solutions to a singularly perturbed second-order three-point boundary value problem for nonlinear differential systems. The authors construct an appropriate generalized lower- and upper-solution pair, a concept defined in this paper, and employ the Nagumo conditions and algebraic boundary layer functions to ensure the existence of solutions of the problem. The uniformly valid asymptotic estimate of the solutions is given as well. The differential systems have nonlinear dependence on all order derivatives of the unknown.     

一类非线性不确定奇异摄动系统的鲁棒镇定

研究非线性不确定奇异摄动系统的鲁棒稳定性问题.基于引入状态变换矩阵以及构造Lyapunov函数得到了非线性不确定奇异摄动系统稳定的上界ε*,并且获得了该类系统渐近稳定的充分条件,最后给出数值例子来说明如何使用所获得的结果.     

讨论扰动方程稳定性的Liapunov函数法

本文提出了一种新的Liapunov函数法讨论时变时滞系统的稳定性问题,我们得到了简洁的稳定性判据。本文的第二部分讨论扰动迭代系统的稳定扰动界限。     

含有双参数的非局部反应扩散方程的奇摄动问题

1 Introduction A kind of problems for ordinary differentialequations with two small parameters has been studiedin [1 -4] and a class of singularly perturbed reaction-diffusion equations has been studied in [5 -6] . Untilnow, few papers discussed the partial differentialequation with two small parameters .Now we considera class of non-local reaction-diffusion equations involv-ing two parameters as follows : u t-(εL1u μL2u) =f(x,u,Tu) , 0 相似文献   

Nonlinear predator-prey singularly perturbed Robin Problems for reaction diffusion systems

INTRODUCTIONThenonlinearsingularlyperturbedproblemisaveryattractiveobjectofstudyininternation alacademiccircles (DeJageretal.,1996 ) .Intherecent 10years,manyapproximationmeth ods,includingthemethodofaveraging,bound arylayermethod ,matchedasymptoticexpans…     

Traversing the singularity hypersurface by applying the input disturbances to 6-SPS parallel manipulator

The singular points of a 6-SPS Stewart platform are distributed on the multi-dimensional singularity hypersurface in the task-space, which divides the workspace of the manipulator into several singularity-free regions. Because of the motion un- certainty at singular points, while the manipulator traverses this kind of hypersurface from one singularity-free region to another, its motion cannot be predetermined. In this paper, a detailed approach for the manipulator to traverse the singularity hypersurface with its non-persistent configuration is presented. First, the singular point transfer disturbance and the pose disturbance, which make the perturbed singular point transfer horizontally and vertically, respectively, are constructed. Through applying these disturbances into the input parameters within the maximum loss control domain, the perturbed persistent configuration is transformed into its corresponding non-persistent one. Under the action of the disturbances, the manipulator can traverse the singularity hypersurface from one singularity-flee region to another with a desired configuration.     

微扰sine-Gordon孤子的稳定性

考虑一个微扰sine－Gordon方程的孤子解,应用Lyapunov稳定性分析证明：受扰孤子是稳定的,当且仅当系统参数和孤子速度满足一定的条件．利用该条件,人们可以设置和调节控制参数,控制孤子的稳定性,以达到应用的目的．     

光学孤子系统的微扰效应(英文)

考虑一个由微扰非线性Ｓｃｎｒａａｉｎｇｅｒ方程支配的光学孤子系统，在一级近似下，作者用直接微扰法得到孤子解及其存在条件，即微扰参数与孤子振幅间的一个关系。分析结果与早先的实验数据较好地一致。