基于场量分析的涡流无损检测技术

鉴于微型探头技术的发展和精确诊断缺陷的需要,提出基于场量分析的涡流无损检测技术。与传统的阻抗分析方法不同,它是通过分析扰动磁场的分布进行缺陷识别的。

通过扰动磁场识别缺陷

在涡流检测中 ,扰动磁场的分布比线圈的阻抗能够更好地反映缺陷信息。研究缺陷参数与扰动磁场的对应关系 ,通过扰动磁场的分布识别缺陷。

涡流检测的现状及新进展

对涡流检测法中的几个方面做了介绍,首先介绍激励电场从单频、多频到频带检测的发展趋势,然后介绍涡流检测中数据分析物理量,重点介绍了涡流检测中的数据处理方法及有限元数值计算方法.

Numerical analysis of multicomponent responses of surface-hole transient electromagnetic method

We calculate the multicomponent responses of surface-hole transient electromagnetic method. The methods and models are unsuitable as geoelectric models of conductive surrounding rocks because they are based on regular local targets. We also propose a calculation and analysis scheme based on numerical simulations of the subsurface transient electromagnetic fields. In the modeling of the electromagnetic fields, the forward modeling simulations are performed by using the finite-difference time-domain method and the discrete image method, which combines the Gaver–Stehfest inverse Laplace transform with the Prony method to solve the initial electromagnetic fields. The precision in the iterative computations is ensured by using the transmission boundary conditions. For the response analysis, we customize geoelectric models consisting of near-borehole targets and conductive wall rocks and implement forward modeling simulations. The observed electric fields are converted into induced electromotive force responses using multicomponent observation devices. By comparing the transient electric fields and multicomponent responses under different conditions, we suggest that the multicomponent-induced electromotive force responses are related to the horizontal and vertical gradient variations of the transient electric field at different times. The characteristics of the response are determined by the varying the subsurface transient electromagnetic fields, i.e., diffusion, attenuation and distortion, under different conditions as well as the electromagnetic fields at the observation positions. The calculation and analysis scheme of the response consider the surrounding rocks and the anomalous field of the local targets. It therefore can account for the geological data better than conventional transient field response analysis of local targets.

Experimental and simulation investigation into the cause and treatment of rail corrugation for metro

The cause and treatment of rail corrugation for the metro have always been a popular and challenging issue. In this work, the field measurements were carried out on rail corrugation, track stiffness, and the track dynamic response. A three-dimensional finite element model was developed to investigate the cause of rail corrugation. The constraints on rail vibration from two wheelsets and adjacent wheel-rail interactions were taken into account in the model. According to experimental and simulation results, the suppression measure for rail corrugation was proposed and the suppression mechanism was discussed. It was found that the cause of rail corrugation is related to vertical and lateral vibration of the rails outside the two wheelsets at around 380 Hz. The increased stiffness of the fasteners reduces the vibration energy of the rail and the wheel-rail force. However, simply increasing the stiffness of the fasteners may not be effective in the suppression of rail corrugation. If necessary, the rails need to be grinded to reduce the roughness to a certain level, so that increasing the fastener stiffness can effectively suppress the rail corrugation.

Three-dimensional conjugate gradient inversion of magnetotelluric full information data

Based on the analysis of impedance tensor data, tipper data, and the conjugate gradient algorithm, we develop a three-dimensional （3D） conjugate gradient algorithm for inverting magnetotelluric full information data determined from five electric and magnetic field components and discuss the method to use the full information data for quantitative interpretation of 3D inversion results. Results from the 3D inversion of synthetic data indicate that the results from inverting full information data which combine the impedance tensor and tipper data are better than results from inverting only the impedance tensor data （or tipper data） in improving resolution and reliability. The synthetic examples also demonstrate the validity and stability of this 3D inversion algorithm.

A back analysis of the temperature field in the combustion volume space during underground coal gasification

The exact shape and size of the gasification channel during underground coal gasification(UGC) are of vital importance for the safety and stability of the upper parts of the geological formation.In practice existing geological measurements are insufficient to obtain such information because the coal seam is typically deeply buried and the geological conditions are often complex.This paper introduces a cylindrical model for the gasification channel.The rock and soil masses are assumed to be homogeneous and isotropic and the effect of seepage on the temperature field was neglected.The theory of heat conduction was used to write the equation predicting the temperature field around the gasification channel.The idea of an excess temperature was introduced to solve the equations.Applying this model to UCG in the field for an influence radius,r,of 70 m gave the model parameters,u1,2,3...,of 2.4,5.5,8.7...By adjusting the radius(2,4,or 6 m) reasonable temperatures of the gasification channel were found for 4 m.The temperature distribution in the vertical direction,and the combustion volume,were also calculated.Comparison to field measurements shows that the results obtained from the proposed model are very close to practice.

Oil Crisis, Market Reforms, and Human Welfare： An Econometric Analysis of the Australian Economy

As an active trader in international crude oil and petroleum product markets, Australia＇s human welfare is affected by oil crisis and contagion from the perspectives of economic growth, income inequality, and environmental sustainability. This paper investigates the impacts of oil price shocks upon Australia＇s gross domestic product （GDP） growth, Gini coefficients, and carbon dioxide emissions per capita from 1970 to 2012 with yearly frequency. Hypotheses concerning whether Australia＇s economic immunity against oil crisis is affected after the deregulation of oil market and whether endogenous oil price shocks account for more variations in human welfare than exogenous oil price shocks are tested. The methodologies include a theoretic model and a series of econometric tests. For the short-run dynamics, oil price is integrated into the model both linearly and non-linearly. Oil price shocks are categorized into exogenous and endogenous shocks. The conclusions are that inflated oil prices exert mainly non-linear negative impacts upon human welfare indicators and exogenous shocks induce endogenous shocks through labor price, Consumer Price Index （CPI）, interest rate, and exchange rate. For the long-run equilibrium, non-linear shocks＇ effects decay more slowly than linear shocks and the impacts of endogenous shocks last longer than that of exogenous shocks. Finally, oil market policies are evaluated and proposed.

Market Analysis of Typical Products in Italy： Bivariate Statistical Relationships Between Qualitative Variables

The denominations of origin being perceived by the consumers in terms of both intrinsic qualities and of extrinsic qualities, have contributed in no uncertain manner to the increase of the typical products in question, positively influenced also by the noted emergencies coming from verified alimentary alarms during the beginning of the XXI century. The objective of this paper, is to determine the habits of purchase of typical and traditional products of the people of Messina （Sicily, Italy）. To do this a ＂motivational＂ survey was carried out by traditional methodology of descriptive researches. The adopted methodology of research was quantitative and random. The random research strives to identify the factors that depend on the behaviour of purchase and the appraisal of the existing relationships of cause-effect in a determined population. The interviewed were given a questionnaire composed of 17 questions on their knowledge of the typical products characteristics, the frequency of consumption, the monthly amounts destined to the purchase, the motivations that push them to the purchase of typical products rather than pre-packed. Methodologically, our statistical analysis has been performed using the log-likelihood ratio test in order to investigate the existence of association between the joint distributions of qualitative measured variables.

GH4169合金叶片终锻成形宏观场量规律数值模拟

通过有限元数值模拟,采用选取GH4169合金叶片终锻件上典型截面及追踪预锻件上特征点在整个终锻成形过程中金属流动特点及变化趋势的研究方法,从而较深入全面的揭示了不同工艺参数下叶片终锻成形演化规律。研究结果显示:等效应变及应力场的分布均随着始锻温度的升高而愈均匀;等效应力场、温度场及载荷-行程曲线对于上模下压速度敏感性较强,较大的变形速度引起大温升,还易使变形体内部组织晶格形变,产生大的附加应力及应力集中,且上模出现瞬时峰值载荷的时间越早但次数反而越多;摩擦因子的增大对叶身中部纵向截面最低温度升幅影响较大,增加了锻造难度的同时使变形渐不均匀。

Economical Analysis of Milk Production in the Farms of Siedlce Region

Last years the most profitable line of activity in agriculture is considered with milk production. The-effectiveness of this project depends primarily on the direct costs and the obtained of purchase price. Therefore the aim of this work was to analyze the financial results of dairy farms in the east part of Mazovia region. Completing the research in 2010, to the owners of 36 farms were sent a questionnaire containing 18 questions. The obtained data were used to characterize the various research facilities. And then the whole population was devoted on the 6 production groups, depend on the number of physical units of dairy cows. Moreover, based on survey data, an analysis of the profitability of milk production was done. It was the following economic values： direct costs, revenue, gross margin and the index of production profitability. Also the statistical analysis by calculating the Pearson linear correlation coefficient （r） and coefficient of determination （R2） was done. The study showed that the highest annual yield of milk from a cow at the level of 7500 kg, reached the farmers with the area of l 9.7 ha of with the density of 1.82 BFU/ha and with 8 years of cow utilization. Respondents from this group also received the highest value of effectiveness index （184.60%）. In addition, the performed regression analysis showed significant positive correlation between the effectiveness index and the surface agricultural lands occurring in the farms, density of agricultural lands, and efficiency from a cow and the price of milk.

Novel Quantum Phases of Ultracold Bosonic Atoms in Honeycomb Optical Lattice

We study the quantum phase transition of ultracold atoms in the honeycomb optical lattice. The Hamiltonian of ultracold bosonic atoms in the honeycomb optical lattice is derived. We take the mean-field approximation and further solve the Hamiltonian with the numerical diagonalization method. We obtain the phase diagram and find that the Mort-insulator （MI）, density wave （DW） and modulated superfluid （MS） phases appear. Furthermore, the phase diagram is analyzed according to the order parameter and the average number of particles.

Analyzing the Impacts of Minimum Wage Standards on Reducing the Working Poor in China

During the past decades, the transformation of the labor market has significantly impacted on workers＇ wage structures and their employment in China. Along with the widening wage gaps and the growing income inequalities, the size of non-standard jobs expanded rapidly in China＇s urban labor market. As a result of this, the concept of working poor has become increasingly applicable to social and labor market realities in China, Based on the household survey data and by using quantitative analysis, this paper attempts to examine the interaction between the compulsory minimum wage standards and the working poor in the period of China＇s economic transition. The results show that for those whose monthly wages higher than the compulsory minimum wage standards were less likely to work poor and that workers with wages lower than the minimum wage floor were vulnerable to working poor, which supported the expectation that the implementation of compulsory minimum wages would help to reduce the risk of being a member among the working poor in China＇s urban labor market.

Effect of Market Power in Electricity Markets

The main objective of this paper is to show an overview analysis of market power issues.Market power reflects the scarcity of power supply.It is the ability of a particular seller or group of sellers to maintain prices profitably above competitive levels for a significant period of time.Because the electric power system has its own characteristics that are different to other economic systems,both physical factors and economic factors of power system are key elements on this definition.We study some cases here,including different line limit levels,load levels and bid strategy through a market model based on OPF (optimal power flow) with a decommitment algorithm.

Market orientation for the hotel segment： The Portuguese case

In view of the importance of the hotel segment for the tourism and for the economy of countries such as Portugal, the objective of this study was to measure the level of orientation for the market of the largest hotel groups of Portugal. This investigation initially emphasized the importance of the marketing for the organizations, mainly the orientation for the market. After a brief explanation on the hotel segment in Portugal, an empirical study was presented, of quantitative, exploratory and traversal character, performed with the largest groups of 20 hotels of Portugal, using as an instrument of collection data, the traditional Markor scale （market orientation） adapted to the hotel sector. After analyzing the data, it was found in the investigated organizations that a good capacity to generate market information and response to the market, which formed two of the three constructs of Markor scale. However the results obtained with the construct of the dissemination of market information were below the expectations. It was possible to conclude that marketing professionals of the large hotel groups in Portugal are well oriented to the market, something not shared by other investigated departments of the hotels. So the current challenge for the main networks of hotels in Portugal is to improve the internal dissemination of information that marketing professionals gathered at the market.

The Implementation of Radiological Characterization for Reactor Decommissioning

The radiological characterization is to determine the type, the distribution and the radioactivity of the radionuclide in the reactor by investigation of the information, instrumentation detection, sampling analyses and theoretical calculation. It is used for determination of the decommissioning implementation option and radiological protection measure of the workers. After completion of the decommissioning it is used for determination of the site release. The radiological characterization should go through whole decommissioning process, which includes： the collection and review of historical file, the performing calculation of radionuclide inventory in the reactor, in situ measurement, sampling analyses, the review and evaluation of the data obtained and the comparison of calculated result with measured date etc.. The special attention should be paid to the radiological characterization information from the key part of reactor in decommissioning end state. The sampling from the ＂hot spot＂ should not be lost; the number of the sampling should be reasonable based on reliable statistics. The radioactivity density for site release should comply with the guide, standard and regulation of International Atomic Energy Agency and China.

CRUDE OIL PRICE FORECASTING WITH TEI@I METHODOLOGY

The difficulty in crude oil price forecasting, due to inherent complexity, has attracted much attention of academic researchers and business practitioners. Various methods have been tried to solve the problem of forecasting crude oil prices. However, all of the existing models of prediction can not meet practical needs. Very recently, Wang and Yu proposed a new methodology for handling complex systems-TEI@I methodology by means of a systematic integration of text mining, econometrics and intelligent techniques.Within the framework of TEI@I methodology, econometrical models are used to model the linear components of crude oil price time series (i.e., main trends) while nonlinear components of crude oil price time series (i.e., error terms) are modelled by using artificial neural network (ANN) models. In addition, the impact of irregular and infrequent future events on crude oil price is explored using web-based text mining (WTM) and rule-based expert systems (RES) techniques. Thus, a fully novel nonlinear integrated forecasting approach with error correction and judgmental adjustment is formulated to improve prediction performance within the framework of the TEI@I methodology. The proposed methodology and the novel forecasting approach are illustrated via an example.

On the extinction route of a stochastic population model under heteroclinic bifurcation

The noise-induced transition of the augmented Lotka-Volterra system is investigated under vanishingly small noise.Populations will ultimately go extinct because of intrinsic noise,and different extinction routes may occur due to the Freidlin-Wentzell large deviation theory.The relation between the most probable extinction route(MPER)and heteroclinic bifurcation is studied in this paper.The MPERs and the quasi-potentials in different regimes of parameters are analyzed in detail.Before the bifurcation,the predator goes extinct,and the prey will survive for a long time.Then,the heteroclinic bifurcation changes the MPER wherein both species go extinct.The heteroclinic cycle plays a role in transferring the most probable extinction state.Moreover,the analyses of the weak noise limit can contribute to predicting the stochastic behavior under finite small noise.Both the heteroclinic bifurcation and the rotational deterministic vector field can reduce the action necessary for the MPER.

Quantitative analysis of nanoscale deformation fields of a crack-tip in single-crystal silicon

A mode II crack in single-crystal silicon was investigated experimentally using high-resolution transmission electron microscopy.Geometric phase analysis and numerical moiré method were employed to map the deformation fields of the crack-tip area.The normal strain field maps of the crack-tip area indeed showed the deformation occurs primarily in the vicinity of the dislocations and the normal strains are near zero in the crack-tip area.The shear strain field map shows that the relatively large shear strain is in the crack-tip area.The experimental results were compared with the predictions of linear elastic fracture mechanics.The comparison shows that measured strain distribution ahead of the crack-tip agrees with the predictions of linear elastic fracture mechanics up to 1 nm from the crack-tip.

Chelating agents role on phase formation and surface morphology of single orthorhombic YMn_2O_5 nanorods via modified polyacrylamide gel route

YMn2O5nanorods were synthesized through a modified polyacrylamide gel route.The synthesis strategy in this work is based on a sol-gel process using a polyacrylamide gel method in which oxalic acid,citric acid or tartaric acid is employed as the chelating agent.In the gel routes,oxalic acid was used as a carboxyl chelating agent,while citric acid or tartaric acid was a carboxyl and hydroxyl chelating agent.The as-prepared samples were characterized by means of techniques such as X-ray powder diffraction(XRD)measurement,thermogravimetric analysis(TG),differential scanning calorimetry analysis(DSC),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermal expansion measurement and field-emission scanning electron microscopy(SEM)investigations.It was found that oxalic acid is the best chelating agent with Y(NO3)3·6H2O and Mn(CH3COO)2·4H2O as precursors to prepare a single orthorhombic YMn2O5nanorods at 1000°C.Scanning electron microscope observation shows that the morphology of YMn2O5powders is significantly dependent on the chelating agent.The peaks(single orthorhombic YMn2O5nanorods)at 642,600,573,546,521,493,486,468,448 and 400cm?1were observed from FTIR spectra.The phase,surface morphology and chelation mechanisms of YMn2O5samples have been discussed on the basis of the experimental results.