Publications

The development of Global Energy Interconnection (GEI) is essential for supporting a wide range of basic data resources. The Global Energy Interconnection Development and Cooperation Organization has established a comprehensive data center covering six major systems. However, methods for accurately describing and scientifically evaluating the credibility of the massive amount of GEI data remain underdeveloped. To address this lack of such methods, a GEI data credibility quantitative evaluation model is proposed here. An evaluation indicator system is established to evaluate data credibility from multiple perspectives and ensure the comprehensiveness and impartiality of evaluation results. The Cloud Model abandons the hard division of comments to ensure objectivity and accuracy in evaluation results. To evaluate the suitability of the proposed method, a case analysis is conducted, wherein the proposed method demonstrates sufficient validity and feasibility.

Structural physical parameters often vary gradually due to the degradation of material properties or effects of environment. In this paper, two novel approaches are proposed to identify the gradually varying physical parameters based on the discrete cosine transform (DCT) using partial measurements of structural responses. Approach I is proposed for the circumstance of known excitations. The gradually varying physical parameters are first located by the fading-factor extended Kalman filter (FEKF) and then identified by the proposed DCT integrated with Kalman filter (KF) method. Approach II is proposed for the identification of gradually varying physical parameters under unknown excitations. The gradually varying physical parameters are first localized by the proposed fading-factor extended Kalman filter under unknown input (FEKF-UI) and then identified by the proposed DCT integrated with Kalman filter under unknown input (KF-UI). Numerical examples demonstrate that the proposed approaches can identify the gradually varying physical parameters accurately with incomplete measurement data. Moreover, the identification of time-varying cable force in cable-stayed bridge is also discussed as a case study of the proposed approach I. Experimental verification shows that it provides a new path to identify the time-varying cable force by only using one acceleration response measurement of the cable.

A directional blasting method was introduced to demolish a 210m-high chimney of reinforced concrete.Practices and techniques regarding the selection of blasting cut,the determination of blasting parameters,the design of ignition network as well as the pretreatment and safety precautions were presented for precise control of collapse direction of the chimney.Besides,the feasibility of directional blasting demolition of the 210m-high chimney was also explored.The demolition saw a very successful collapse in directional blasting demolition of the 210m chimney,with the top of the chimney falling into the area just 1.5m away from the central line of collapse.

This paper presents a structural damage identification approach based on the time domain impulse response functions, which are extracted from the measured dynamic responses with the input available. The theoretical sensitivity of the impulse response function with respect to the system stiffness parameters considering the damping model is derived. The first-order sensitivity based model updating technique is performed for the iterative model updating. The initial structural finite element model and acceleration measurements from the damaged structure are required. Local damage is identified as a reduction in the elemental stiffness factors. The impulse response function sensitivity based optimal sensor placement strategy is employed to investigate the best sensor locations for identification. Numerical studies on a beam model are conducted to validate the proposed approach for the extraction of time domain impulse response functions and subsequent damage identification. The simulated damage can be identified effectively and accurately.

Abstract Stimulated reservoir volume fracturing, in unconventional gas and tight oil development, is a key technology. Injecting low viscosity sand-laden fluid of high flow rate, it can form complex fracture networks. Therefore, placement of proppant deep into the complex fracture networks brings a conductive path for production enhancement and reduces flowing resistance when fluid flowing form rock matrix to wellbore. At current, it is still unclear that sand features of low viscosity sand-laden fluid of high flow rate, and especially for proppant transport in subsidiary fractures are also not clearly understand. In this study, we fully think about the practical condition of engineering. Thus, in terms of similarity criterion of geometry and Reynolds number, we build a large scale of proppant placement in visualization complex fracture networks device which can changes angles of fractures, width of fractures and numbers of fractures. Due to the single factors experiment, this paper will discuss a series tests to evaluate proppants transport in complex fracture networks. Different slick water treatment tests are simulated by pumping sand slurry through the visualization complex fracture networks device while varying parameters of perforation, angles of fractures, proppant size, pump rate and proppant concentration. From the experiment, treatment tests which are used in variable factors can obtain different laws about traction carpet feature, traction carpet areas, balance hight and balance time in complex fracture networks. This paper also describes a 3-D physical model. This model is designed by SolidWorks software and using grid software to make complex fracture grids. Afterwards, using fluent software to simulate proppant concentration distribution field in the model of complex fracture networks. In addition, comparing the results between physical model and numerical model, the results can reveal, during the process of SRV, the law of proppant placement in complex fracture networks and serve as guidelines for engineering design.

In this study, a mock-up of a nuclear safe-end dissimilar metal weld (DMW) joint (SA508-3/316L) was manufactured. The manufacturing process involved cladding and buttering of the ferritic steel tube (SA508-3). It was then subjected to a stress relief heat treatment before being girth welded together with the stainless steel tube (316L). The finished mock-up was subsequently machined to its final dimension. The weld residual stresses were thoroughly characterised using neutron diffraction and the contour method. A detailed finite element (FE) modelling exercise was also carried out for the prediction of the weld residual stresses resulting from the manufacturing processes of the DMW joint. Both the experimental and numerical results showed high levels of tensile residual stresses predominantly in the hoop direction of the weld joint in its final machined condition, tending towards the OD surface. The maximum hoop residual stress determined by the contour method was 500 MPa, which compared very well with the FE prediction of 467.7 Mpa. Along the neutron scan line at the OD subsurface across the weld joint, both the contour method and the FE modelling gave maximum hoop residual stress near the weld fusion line on the 316L side at 388.2 and 453.2 Mpa respectively, whereas the neutron diffraction measured a similar value of 480.6 Mpa in the buttering zone near the SA508-3 side. The results of this research thus demonstrated the reasonable consistency of the three techniques employed in revealing the level and distribution of the residual stresses in the DMW joint for nuclear applications.

Medical images provide intuitive visualization methods and provide reliable basis for disease diagnosis and treatment. In the process of medical image acquisition, transmission and recording, noise information will inevitably be introduced due to the influence of transmission medium errors, measurement errors and the quantization of digital information. Noisy images not only reduce the image quality and affect the visual effect, but also blur or obscure the important information of the image. In order to obtain clear and noise-free medical images, this paper proposes an adaptive median filter image denoising method. Firstly, the noise points and signal points in the image are judged, and only the noise points are processed. Then, in the process of removing noise signal, we fully consider the pixel distribution feature information around the noise point and replace the pixel value of the noise point. This method has a good ability to remove noise and it can effectively deal with impulse noise while protecting the details of the image.