800 publications from this institution
Abstract Along with the advancement in sensing and communication technologies, the explosion in the measurement data collected by structural health monitoring (SHM) systems installed in bridges brings both opportunities and challenges to the engineering community for the SHM of bridges. Deep learning (DL), based on deep neural networks and equipped with high-end computer resources, provides a promising way of using big measurement data to address the problem and has made remarkable successes in recent years. This paper focuses on the review of the recent application of DL in SHM, particularly damage detection, and provides readers with an overall understanding of the missions faced by the SHM of the bridges. The general studies of DL in vibration-based SHM and vision-based SHM are respectively reviewed first. The applications of DL to some real bridges are then commented. A summary of limitations and prospects in the DL application for bridge health monitoring is finally given.
Abstract The challenge of the alpha/beta waves gravel packing open hole in offshore Brazil is how to successfully displace the proppant slurry in a large wellbore with a low fracture gradient formation, deep to ultra-deep water depths, and extended reach horizontal section. Since 2001, job data from more than 72 open hole horizontal gravel packings have been compiled into a database. This paper reviews the well information and the key gravel packing parameters: pump rate, fluid density, injection proppant concentration, inner/outer annulus area ratio, dune ratio, packing rate, packing time and packing efficiency during alpha/beta waves. The engineering implementations and challenges, the best practices and lessons learned for open hole horizontal gravel packing are also summarized. The data analysis yields a better understanding about the open hole horizontal gravel packing in the Brazil offshore and provides a good guideline for future practice. A historical review is also presented showing how the gravel packing methodology has improved packing efficiency and success rate. Case histories are provided demonstrating how to deploy the single trip system and pack the extended reach wellbore utilizing ultra-light-weight (ULW) proppant under extreme with improved packing efficiency and the success rate.
The synchronizer is often used for the measurement of axis-angle because of its simple structure, reliability and high precision. But the output signal from the synchronizer is an analog signal, so it is difficult to realize digital measurement. This paper introduces a measuring circuit based on a singlechip. This circuit can produce exciting signal independently and no extra exciting power supply is needed, making the application easy. The AC signals output from the synchronizer are converted into DC signals and then measured directly by the singlechip. The measuring data, after being processed, are turned into serial data to output through a RS232 serial interface. The synchronizer equipped with the circuit will be a digital axis-angle sensor. The sensor is of high precision and reliability, low price, easy application and high practical value.
System-in- Package (SiP) aims to integrate a functional subsystem, one or more semiconductor chips and passive components into a package, so as to realize a basically complete function. The power module based on system-in-package (SiP) has many structural and performance advantages, such as miniaturization, high heat dissipation, low impedance and so on, which fits the development trend of electronic packaging towards miniaturization and high performance. In this paper, the random vibration simulation analysis of a power module is carried out by using finite element simulation software, and the influence of random vibration load onto the stress on the micro bumps on the adapter board in the power module is studied, and the potential risk points are determined before the product manufacture, thus improving the product reliability, reducing the development cost and shortening the development cycle.
The low temperature co-fired ceramic (LTCC) technology has already become an integrated technology of electric components. As a new integrating and packing technology, it have successfully applied to the integrating technology of the passive component for its excellent high frequency high Q and high speed transfer characteristics. The manufacturing process of the LTCC and its extensive application prospect are introduced particularly.
Nonlinear characteristics in the dynamic behaviors of civil structures degrade the performance of damage detection of the linear theory based traditional time- and frequency-domain methods. To overcome this challenge, this paper proposes a damage detection approach for nonlinear structures based on Variational Mode Decomposition (VMD). In this approach, the measured dynamic responses from nonlinear structures under earthquake excitations are adaptively decomposed into a finite number of monocomponents by using VMD. Each decomposed mono-component represents an amplitude modulated and frequency modulated (AMFM) signal with a limited frequency bandwidth. Hilbert transform is then employed to identify the instantaneous modal parameters of the decomposed monomodes, including instantaneous frequencies and mode shapes. Based on the identified modal parameters from the decomposed structural dynamic responses, two damage indices are defined to identify the location and severity of structural damage, respectively. To validate the effectiveness and accuracy of the proposed approach, a nonlinear seven-storey shear building model with four different damage cases under earthquake excitations is used in the numerical studies. In experimental verifications, data from shake table tests on a 12-storey scaled reinforced concrete frame structure with different earthquake excitations are analyzed with the proposed approach. The results in both numerical studies and experimental validations demonstrate that the proposed approach can be successfully applied for nonlinear structural damage identification.
To provide a basis for regional economics decision-making, based on the theory of fuzzy neural networks (FNN) an environmental Kuznets curve (EKC) was investigated quantitatively by predicting the coordination degree of environment and economic development. As an example, the coordination degree of environment and economic development of Chengdu City, Sichuan Province, was predicted, and based on the predicted result, the relationship between the environment and economic development of Chengdu City was analyzed. The analysis shows that there is not a marked peak value on its environmental Kuznets curve, i.e., the relationship between its environment and economic development tends towards coordination.
Wavelet shrinkage de-noising is applied to electrophoretic nuclear magnetic resonance (ENMR) data. Both threshold rules for removing noise, namely soft and hard, proposed in Donoho's (1993) VisuShrink, are used simultaneously. Soft thresholding is applied to fine levels of wavelet decomposition coefficients and hard thresholding is applied to coarse levels. This implementation is coordinated by visualizing the features presented in ENMR spectra.
Aimed to the needs for interoperability and comprehensive integration on fieldbus, On the basis of introducing the characteristics of EDD (Electronic Device Description) and FDT (Field Device Tool) , an integration model based on EDD and FDT is proposed. Through embedding the EDDL (Electronic Device Description Language) interpreter into the device DTM and adding the user interface generator module in the DTM UI (User Interface), when the interpreter parse an EDD file, in terms of contents of the device description the intermediate data structure is generated, and by interacting with the view builder user interfaces are automatically generated, and then the operation for the device with EDD can be implemented. As a consequence, the FDT frame application support both DTM (Device Type Manager) and EDD. Inner logic of the model is clarified, and the implementation of interpreter and user interface is specified in detail. The DTM based on EDD can be easily integrated into existing FDT frame application, attaining a purpose of flexible and wide device integration.
