Publications

Improved decentralized structural identification with output-only measurements

Three dimensional printing of carbon/carbon composites by selective laser sintering

A Novel Short-term Multi-energy Load Forecasting Method Based on VMD-MPA and Optimal Bagging Ensemble Learning

Dynamic Assessment of Shear Connectors in Composite Bridges with Ambient Vibration Measurements

Shear connectors are normally used in composite bridges, such as slab-on-girder structures, to link the slab and girder together. Damage of shear connectors will result in shear slippage between slab and girder, which significantly reduces the load-carrying capacity of the bridge. Routine visual inspection is not able to detect conditions of shear connectors because they are buried inside the structure. This paper proposes a dynamic damage detection approach based on wavelet packet energy of cross-correlation functions from ambient vibration measurements to identify the damage of shear connectors in slab-on-girder bridges. Measured acceleration responses on the slab and corresponding girder locations under ambient vibrations are used to compute the cross-correlation functions. Wavelet packet decompositions of cross-correlation functions from the undamaged and damaged structures are performed and the percentage of wavelet packet energy in selected frequency bandwidths to the total wavelet packet energy is used to calculate the damage index. Numerical and experimental studies on a composite bridge with a concrete slab supported by two steel girders are conducted to validate the proposed approach and investigate its performance and robustness with noisy measured responses. It is demonstrated that the introduced damage of shear connectors can be identified accurately and efficiently.

Analysis of Nonlinear Contact Force in Anchorage Zone of Cable Tower on Chongqing Dongshuimen Yangtze River Bridge

A novel structure is adopted in anchorage zone of cable tower on Chongqing Dongshuimen Yangtze River Bridge,the end plates in anchorage zone of common external steel anchor box cable tower are cancelled,and the steel anchor boxes are connected with concrete tower limbs by means of shear studs,in the mean time the prestress among tower limbs is arranged,enabling close connection between the steel anchor boxes and concrete,and the shear studs,side pulling plates and friction force are used to bear the force of stayed cables.Aiming at this novel structure,this paper establishes a nonlinear contact model for anchorage zone of cable tower via large-scale finite element software Midas FEA,the stress distribution in the steel anchor boxes,side pulling plates,shear studs and concrete on tower walls are acquired as well as transfer and distribution of cable force based on exquisite simulation calculation for the model.

Improving identifiability of structural damage using higher order responses and phase space technique

ELECTRE Method Based on Interval-Valued Intuitionistic Fuzzy Number

A new multi-criteria decision-making method for interval-valued intuitionistic fuzzy number is proposed by the advantage of intuitionistic fuzzy set and ELECTRE method. Firstly, the possibility-degree and deviation-degree of interval number are used to establish the preference relation of interval-valued intuitionistic fuzzy number. Then, we exposit the decision theory and the steps of this method. Finally, a numerical example is given to illustrate the application of the method. The numerical results show that it is feasible and effective.

Speed sensorless control of bearingless motor

The performance of surface permanent magnet bearingless snchronous motor(sPMBLM) system is usually affected by its parameter unknown or change with temperature and saturation.An online identification method for sPMBLM was presented based on current pridiction using the grey prediction method.The position and speed sensorless control system of sPMBLM based on system identification was proposed.The simulating and experimental results show that this method has such advantages as simple model,rapid convergence and small error.The system can achieve the stable suspension under the larger interference.

Physical-Layer Counterattack Strategies for the Internet of Bio-Nano Things with Molecular Communication

Molecular communication (MC) is an emerging new communication paradigm where information is conveyed by chemical signals. It has been recognized as one of the most promising physical layer techniques for the future Internet of Bio-Nano Things (IoBNT), which enables revolutionary applications beyond our imagination. Compared with conventional communication systems, MC typically demands a higher security level as the IoBNT is deeply associated with the biochemical process. Against this background, this article first discusses the security and privacy issues of IoBNT with MC. Then, the physical-layer countermeasures against the threat are presented from an interdisciplinary perspective concerning data science, signal processing techniques, and the biochemical properties of MC. Correspondingly, both the keyless and key-based schemes are conceived and revisited. Finally, some open research issues and future research directions for secrecy enhancement in IoBNT with MC are put forward.

Finite Linear Representation of Nonlinear Structural Dynamics Using Phase Space Embedding Coordinate

Modeling of structural nonlinear dynamic behavior is a central challenge in civil and mechanical engineering communities. The phase space embedding of response time series has been demonstrated to be an efficient coordinate basis for data-driven approximation of the modern Koopman operator, which can fully capture the global evolution of nonlinear dynamics by a linear representation. This study demonstrates that linear and nonlinear structural dynamic vibrations can be represented by a universal forced linear model in a finite dimension space projected by time-delay coordinates. Compared with the existing methods, the proposed approach improves the performance of finite linear representation of nonlinear structural dynamics on two essential issues including the robustness to measurement noise and applicability to multidegree-of-freedom (MDOF) systems. For linear structures, the dynamic mode shapes and the corresponding natural frequencies can be accurately identified by using the time-delay dynamic mode decomposition (DMD) algorithm with acceleration response data experimentally measured from an 8-story shear-type linear steel frame. Modal parameters extracted from the time-delay DMD matched well with those identified from traditional modal identification methods, such as frequency domain decomposition (FDD) and complex mode indicator function (CMIF). In addition, numerical and experimental studies on nonlinear structures are conducted to demonstrate that the finite-dimensional DMD based on the discrete Hankel singular value decomposition (SVD) coordinate is highly symmetrically structured, and is able to accurately obtain a linear representation of structural nonlinear vibration. The resulting linearized data-driven equation-free model can be used to accurately predict the responses of nonlinear systems with limited training data sets.

A Label Embedding Algorithm Based on Maximizing Normalized Cross-Covariance Operator

The Design of Signal Generator based on Virtual Instrument

The paper design a Virtual Signal Generator based on Virtual Instrument,which can produce continuous adjustable amplitude and frequency signal .It's contains of the most basic three waveform: sine wave, pulse wave and triangle wave.We design the signal generator by LabVIEW.Data acquisition is NIUSB-6009.By the measurement we can seen from function to output signal parameters of the virtual signal generator are similar as the results of actual measurement.

Study On the Simulation Performance of Two-sided Segmented Wavemakers

Segmented wavemakers which consist of numerous individually programmed paddles have become important in the study of wave and its interaction with ocean engineering structures in ocean basin. There are some key problems greatly affecting the simulation quality of segmented wavemakers, including the limitation of direction angle of oblique wave simulation induced by paddle width and wave period, the generation of spurious waves and the effective test area of 3D shortcrested wave. The following results are obtained through the analysis of the performance of two-sided segmented wavemakers:(1)The relationship between oblique wave angle and wave period; (2)Wave direction limitation to prevent spurious waves; (3)Effective test area of simulated 3D short-crested wave. The results are significant to high quality wave simulation and providing better wave environment conditions for model tests of various ocean engineering structures in deep ocean basin.

FEM Analysis on the Lateral Earth Pressure of the Retaining Wall with the Relieving Platform

FEM simulation construction process was carried on the relieving platform retaining wall which often used in hydraulics and communication civil engineering.This kind of retaining wall was researched on its influential factors,such as the distribution of earth pressure,the width of plat and its height,on lateral soil pressure.It was a good reference for the design of practical engineering construction.

Route Reconstruction from Floating Car Data with Low Sampling Rate Based on Feature Matching

Floating Car Technology is widely used to collect traffic information. To reappear the actual trips of drivers, a bi-level probability method is proposed to reconstruct routes from floating car data, address two issues: the first one is incorrect map matching caused by GPS accuracy and complexity of road network; and the second one is the link missing duo the low sampling rate of floating car. Using confidence region, GPS points are divided into three types: zero-feature points with no feature matching, single-feature points that have a unique matched link or node and multiple-features points that have multiple features. The matching probability for GPS points to the possible feature according to the distance between GPS point and the link, which is assumed to be normal distribution. The missing links between two single-feature points are reconstructed by the shortest path algorithm with consideration of the probability of multiple matched features. A case study of Guangzhou floating car data shows that the proposed method can produce reasonable routes on complicated urban road network.

Damage detection of wind turbine blades by Bayesian multivariate cointegration

Investigation of Traffic Loading Effects for Different Codes on Medium- and Small-Span Girder Bridges in China

With increasing traffic volume, the traffic load grade given by design codes has gradually increased. For new bridges, there is no problem, and the traffic load can be met through the requirements of the new code. However, for existing bridges, there is a lack of uniform standards on whether they can continue to be used. It is not clear whether these bridges will be judged according to the new code or the original design code. The traffic loading effects of different codes on medium‐ and small‐span girder bridges in China are investigated in this study. Three codes are introduced: JTJ 021‐89, JTG D60‐2004, and JTG D60‐2015. Simply supported girder bridges and continuous girder bridges are discussed. The traffic loading effects calculated based on JTG D60‐2015 are significantly larger than those calculated based on JTJ 021‐89. For simply supported girder bridges, most of the differences range from 20% to 40%, and the maximum value is almost larger than 60%. For continuous girder bridges, most of the differences in the positive bending moments are concentrated in the 20%∼40% range, while the differences in the negative bending moments range from 10% to 20%. Therefore, the differences in traffic loading effects calculated based on various codes cannot be ignored in actual bridge engineering. The conclusion in this study can provide a basis for bridge structure evaluation and life prediction.

Deep learning based data anomaly detection considering data imbalance and extreme loadings