工业铂热电阻ITS—90的分度函数的讨论

介绍了意大利国家计量院和中国上海工业自动化仪表研究所对t≥0℃范围的R-t特性进行的研究和分析,重点讨论了它们之间的异同和优缺点.

辐射温度计分度方法探讨

研讨了辐射温度计的标定方法，提出了1种新的标定法──分度函数法；并以Ge光电池为例，导出其分度函数的具体形式，同时估算了分度误差。

铂电阻高精度非线性校正及其在智能仪表中的实现

以铂电阻分度函数为基础 ,给出了 2种高精度非线性校正的算法 ,其结果已在智能仪表中得到应用 ,并达到良好的效果。

最小二乘法在石油闪点检测中的应用

以铂电阻分度函数为基础,利用最小二乘法算法,给出了拟合多项式,很好地解决了石油闪点检测系统中铂电阻不平衡电桥法测温方案中的非线性误差,其方便性和实用性已在应用中得到验证。

采用时域与时频域联合特征空间的转子系统碰磨故障诊断

针对转子系统早期碰磨故障,提出了一种基于时域和时频域联合特征提取和分析的方法,并采用该方法对简单转子模型进行了故障诊断。基于BP神经网络和影响函数法,建立了滑动轴承单盘转子碰磨故障动力学模型,并对转子系统碰磨故障进行了数值模拟;分别采用统计学和小波包分解方法,对振动信号的时域和时频域特征进行了提取,综合两者建立了碰磨故障的特征空间,并采用支持向量机(SVM)模型对比分析了基于时域、时频域和综合两者特征空间的故障诊断效果,在此基础上,通过引入可分度函数,将正常振动信号与故障信号同时考虑,对各特征的可分度进行了分析和排序;根据特征分析结果,将特征空间分为高可分度区域和低可分度区域,分别针对单特征和组合特征对碰磨故障进行识别。研究结果表明:单特征的碰磨故障识别率与其可分度函数值呈正相关;组合特征识别效果要优于单特征,且高可分度区域内的组合特征识别效果要明显优于低可分度区域,针对本文所建碰磨故障样本空间,高可分度区域内随机三特征组合平均故障识别率达到90%以上。文中提出的故障特征提取和分析方法可为复杂故障的识别提供参考。

Quantitative Study on Characteristics of the Weibull Distribution

Aim To quantitatively study three characteristics of the Weibull distribution. Methods Theoritical analysis of the three characteristics of parameters of the Weibull distribution was done and mathematics software was used to make some chart analysis. Results 17 equations and 7 figures were made. Conclusion Under the standard form, the class of the Weibull probable density founction(pdf) curves appear double peak shape. Under the standard form, the maximum value point curve of the Weibull pdf takes line t =0 and t=1 as asymptotes. When β = 3 30-3 40, the Weibull distribution is the most similar to the normal distribution.

Calculation of saturation in carbonate reservoirs based on electrical efficiency

We derived an equation for saturation in carbonate reservoirs based on the electrical efficiency model in the case of lacking core data. Owing to the complex pore structure and strong heterogeneity in carbonate reservoirs, the relation between electrical efficiency and water porosity is either complex or linear. We proposed an electrical efficiency equation that accounts for the relation between electrical efficiency and water porosity. We also proposed a power-law relation between electrical efficiency and deep-formation resistivity and analyzed the factors controlling the error in the water saturation computations. We concluded that the calculation accuracy of the electrical efficiency is critical to the application of the saturation equation. The saturation equation was applied to the carbonate reservoirs of three wells in Iraq and Indonesia. For relative rock electrical efficiency error below 0.1, the water saturation absolute error is also below 0.1. Therefore, we infer that the proposed saturation equation generally satisfies the evaluation criteria for carbonate reservoirs.

On n-K Width of Certain Function Classes Defined by Linear Differential Operators in L_2 Space

Let M(u) be an N function, A=D r+∑r-1k=0a k(x)D k a linear differential operator and W M(A) the Sobolev Orlicz class defined by M(u) and A. In this paper we give the asymptotic estimates of the n K width d n(W M(A),L 2[0,1]) .

Improved response surface method and its application in stability reliability degree analysis of tunnel surrounding rock

An approach of limit state equation for surrounding rock was put forward based on deformation criterion. A method of symmetrical sampling of basic random variables adopted by classical response surface method was mended, and peak value and deflection degree of basic random variables distribution curve were took into account in the mended sampling method. A calculation way of probability moment, based on mended Rosenbluth method, suitable for non-explicit performance function was put forward. The first, second, third and fourth order moments of functional function value were calculated by mended Rosenbluth method through the first, second, third and fourth order moments of basic random variable. A probability density the function（PDF） of functional function was deduced through its first, second, third and fourth moments, the PDF in the new method took the place of the method of quadratic polynomial to approximate real functional function and reliability probability was calculated through integral by the PDF for random variable of functional function value in the new method. The result shows that the improved response surface method can adapt to various statistic distribution types of basic random variables, its calculation process is legible and need not itemtive circulation. In addition, a stability probability of surrounding rock for a tunnel was calculated by the improved method, whose workload is only 30% of classical method and its accuracy is comparative.

Analysis of Cost Functions for Retrieving Sea Surface Salinity

Two kinds of Bayesian-based cost functions (i.e., the unconstrained cost function and parameter-constrained cost function) are investigated for retrieving the sea surface salinity (SSS). In low SSS regions, we have analyzed the sensitivity of the two cost functions to geophysical parameters. The results show that the unconstrained cost function is valid for retrieving several parameters (including SSS, wind speed and significant wave height), and the constrained cost function, which largely depends on the accuracy of reference values, may lead to large retrieval biases. Furthermore, as a retrieval parameter, the sea surface temperature (SST) can re-sult in the divergence of other geophysical parameters in an unconstrained cost function due to the strong sensitivity of brightness temperature to SST. By using the unconstrained cost function and the simulated brightness temperature TB with white noises, the retrieval biases of SSS are discussed with the following two procedures. Procedure a): the simulated TB values are first averaged, and then SSS is retrieved. Procedure b): the SSS is directly retrieved from the simulated TB , and then the retrieved SSS values are aver-aged. The results indicate that, for low SSS and SST distributions, the SSS retrieval by procedure a) has less biases compared with that by procedure b), while the two procedures give almost the same retrieval results for high SSS and SST sea regions.

Calculation of One-Valued Control Limits by Control Chart of Angles

The data we use to express angle or direction are entitled directional data. In a plan right angled coordinate system the traditional control chart can’t solve the quality control problem which the characteristic value is angle. This paper analyses and calculates the one valued control limits by control chart of angles.

Elastic and Thermodynamic Properties of CdSe from First-Principles Calculations

The lattice parameters, bulk modulus, phase transition pressure, and temperature dependencies of the elastic constants cij of CdSe are investigated by using the Cambridge Serial Total Energy Package （CASTEP） program in the frame of Density Functional Theory （DFT）. It is found that the phase transitions from the ZB structure to the RS structure and from WZ structure to RS structure are 2.2 GPa and 2.8 GPa, respectively. Our results agree well with the available experimental data and other theoretical results. The aggregate elastic modulus （B, G, E, A ）, the Poisson＇s ratio （v）, the Griuneisen parameter （γ）, the Debye temperature θD on pressure and temperature are also successfully obtained.

Effects of homogeneous-heterogeneous reactions in flow of Powell-Eyring fluid

The steady two-dimensional flow of Powell-Eyring fluid is investigated. The flow is caused by a stretching surface with homogeneous-heterogeneous reactions. The governing nonlinear differential equations are reduced to the ordinary differential equations by similarity transformations. The analytic solutions are presented in series forms by homotopy analysis method(HAM). Convergence of the obtained series solutions is explicitly discussed. The physical significance of different parameters on the velocity and concentration profiles is discussed through graphical illustrations. It is noticed that the boundary layer thickness increases by increasing the Powell-Eyring fluid material parameter(ε) whereas it decreases by increasing the fluid material parameter(δ). Further, the concentration profile increases when Powell-Eyring fluid material parameters increase. The concentration is also an increasing function of Schmidt number and decreasing function of strength of homogeneous reaction. Also mass transfer rate increases for larger rate of heterogeneous reaction.

A strip thickness prediction method of hot rolling based on D_S information reconstruction

To improve prediction accuracy of strip thickness in hot rolling, a kind of Dempster/Shafer(D_S) information reconstitution prediction method(DSIRPM) was presented. DSIRPM basically consisted of three steps to implement the prediction of strip thickness. Firstly, iba Analyzer was employed to analyze the periodicity of hot rolling and find three sensitive parameters to strip thickness, which were used to undertake polynomial curve fitting prediction based on least square respectively, and preliminary prediction results were obtained. Then, D_S evidence theory was used to reconstruct the prediction results under different parameters, in which basic probability assignment(BPA) was the key and the proposed contribution rate calculated using grey relational degree was regarded as BPA, which realizes BPA selection objectively. Finally, from this distribution, future strip thickness trend was inferred. Experimental results clearly show the improved prediction accuracy and stability compared with other prediction models, such as GM(1,1) and the weighted average prediction model.

Effect of composition and aging time on hardness and wear behavior of Cu-Ni-Sn spinodal alloy

Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens were characterized for microstructure and tested for microhardness and wear rate.A hybrid model with a linear function and radial basis function was developed to analyze the influence of nickel,tin,and aging time on the microhardness and tribological behavior of copper-nickel-sin alloy system.The results indicate that increase in the composition of nickel and tin increases the microhardness and decreases the wear rate of the alloy.The increase in the concentration of nickel and tin decreases the peak aging time of the alloy system.

A compound objective reconfiguration of distribution networks using hierarchical encoded particle swarm optimization

With the development of automation in smart grids,network reconfiguration is becoming a feasible approach for improving the operation of distribution systems.A novel reconfiguration strategy was presented to get the optimal configuration of improving economy of the system,and then identifying the important nodes.In this strategy,the objectives increase the node importance degree and decrease the active power loss subjected to operational constraints.A compound objective function with weight coefficients is formulated to balance the conflict of the objectives.Then a novel quantum particle swarm optimization based on loop switches hierarchical encoded was employed to address the compound objective reconfiguration problem.Its main contribution is the presentation of the hierarchical encoded scheme which is used to generate the population swarm particles of representing only radial connected solutions.Because the candidate solutions are feasible,the search efficiency would improve dramatically during the optimization process without tedious topology verification.To validate the proposed strategy,simulations are carried out on the test systems.The results are compared with other techniques in order to evaluate the performance of the proposed method.

Blind source separation based on generalized gaussian model

Since in most blind source separation(BSS)algorithms the estimations of probability density function(pdf)of sources are fixed or can only switch between one sup-Gaussian and other sub-Gaussian model,they may not be efficient to separate sources with different distributions.So to solve the problem of pdf mismatch and the separation of hybrid mixture in BSS,the generalized Gaussian model(GGM)is introduced to model the pdf of the sources since it can provide a general structure of univariate distributions.Its great advantage is that only one parameter needs to be determined in modeling the pdf of different sources,so it is less complex than Gaussian mixture model.By using maximum likelihood(ML)approach,the convergence of the proposed algorithm is improved.The computer simulations show that it is more efficient and valid than conventional methods with fixed pdf estimation.

Spatiotemporal characteristics of wind energy resources from 1960 to 2016 over China

In the paper,daily near-surface wind speed data from 462 stations are used to study the spatiotemporal characteristics of the annual and seasonal mean wind speed(MWS)and effective wind energy density(EWED)from 1960 to 2016,through the methods of kriging interpolation,leastsquares,correlation coefficient testing,and empirical orthogonal function(EOF)analysis.The results show that the annual MWS is larger than 3 m s-1 and the EWED is larger than 75 W m-2 in northern China and parts of coastal areas.However,the MWS and EWED values in southern China are all smaller than in northern China.Over the past 50 years,the annual and seasonal MWS in China has shown a significant decreasing trend,with the largest rate of decline in spring for northern China and winter for coastal areas.The annual MWS in some areas of Guangdong has an increasing trend,but it shows little change in southwestern China,South China,and west of Central China.Where the MWS is high,the rate of decline is also high.The main spatial distributions of the annual MWS and the annual EWED show high consistency,with a decreasing trend year by year.The decreasing trend of wind speed and wind energy resources in China is mainly related to global warming and land use/cover change.

Dynamic Monte Carlo study on the probability distribution functions of tail-like polymer chain

The configurational properties of tail-like polymer chains with one end attached to a flat surface are studied by using dynamic Monte Carlo technique. We find that the probability distribution of the free end in z direction P（Rz） and the density profile p（z） can be scaled approximately by a factor β to be a length independent function for both random walking （RW） and self-avoiding walking （SAW） tail-like chains, where the factor β is related to the mean square end-to-end distance 〈RE〉. The scaled P（Rz） of the SAW chain roughly overlaps that of the RW chain, but the scaled p（z） of the SAW chain locates at smaller βz than that of the RW chain.

A novel scale-free network model based on clique growth

A novel scale-flee network model based on clique （complete subgraph of random size） growth and preferential attachment was proposed. The simulations of this model were carried out. And the necessity of two evolving mechanisms of the model was verified. According to the mean-field theory, the degree distribution of this model was analyzed and computed. The degree distribution function of vertices of the generating network P（d） is 2m^2m1^-3（d-m1 ＋ 1）^-3, where m and m1 denote the number of the new adding edges and the vertex number of the cliques respectively, d is the degree of the vertex, while one of cliques P（k） is 2m^2Ek^-3, where k is the degree of the clique. The simulated and analytical results show that both the degree distributions of vertices and cliques follow the scale-flee power-law distribution. The scale-free property of this model disappears in the absence of any one of the evolving mechanisms. Moreover, the randomicity of this model increases with the increment of the vertex number of the cliques.