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Jing-Liang Liu,Fu-Lian Qiu,Zhi-Ping Lin,Yu-Zu Li,Fei-Yu Liao 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.1
Engineering structures in operation essentially belong to time-varying or nonlinear structures and the resultant response signals are usually non-stationary. For such time-varying structures, it is of great importance to extract time-dependent dynamic parameters from non-stationary response signals, which benefits structural health monitoring, safety assessment and vibration control. However, various traditional signal processing methods are unable to extract the embedded meaningful information. As a newly developed technique, variational mode decomposition (VMD) shows its superiority on signal decomposition, however, it still suffers two main problems. The foremost problem is that the number of modal components is required to be defined in advance. Another problem needs to be addressed is that VMD cannot effectively separate nonstationary signals composed of closely spaced or overlapped modes. As such, a new method named generalized adaptive variational modal decomposition (GAVMD) is proposed. In this new method, the number of component signals is adaptively estimated by an index of mean frequency, while the generalized demodulation algorithm is introduced to yield a generalized VMD that can decompose mode overlapped signals successfully. After that, synchrosqueezing wavelet transform (SWT) is applied to extract instantaneous frequencies (IFs) of the decomposed mono-component signals. To verify the validity and accuracy of the proposed method, three numerical examples and a steel cable with time-varying tension force are investigated. The results demonstrate that the proposed GAVMD method can decompose the multi-component signal with overlapped modes well and its combination with SWT enables a successful IF extraction of each individual component.
Measure Synchronization and Phase Coherence in a High Dimensional Hamiltonian System
Jing Tian,Bo Li,Haibo Qiu 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.8
Partial and complete measure synchronizations (MSs) are investigated in a high-dimensional Hamiltonian system. Here, a four-coupled ring-shaped rotor model is employed. We calculate the averaged energy of each rotor numerically to address the clustering process of measure synchronization. Poincar\'e sections are used to analyze the dynamic mechanism of partial MS and complete MS transitions, and the separatrix crossing is revealed to be the dynamical mechanism behind all different MS transition behaviors. By calculating the averaged frequency of each rotor, we explore the relationship between frequency locking and MS, and reveal a one-to-one correspondence. Furthermore, we find that abrupt changes in global or even partial phase coherence between the phase oscillators can be an indicator for MS transitions, albeit full phase coherence is not equivalent to measure synchronization.
Jing Zhang,Yichao Ma,Mingjun Wang,Dalin Zhang,Suizheng Qiu,Wenxi Tian,Guanghui Su 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.8
Three-layer back propagation network (BPN) and genetic neural network (GNN) were developed in this study to predict the flow boiling heat transfer coefficient (HTC) in conventional and small-diameter channels. The GNN has higher precision than BPN (with root mean square errors of 17.16% and 20.50%, respectively) and other correlations. The inputs include vapor quality x, mass flux G, heat flux q, diameter D and physical parameter φ, and the predicted flow boiling HTC is set as the outputs. Influences of input parameters on the flow boiling HTC are discussed based on the trained GNN: nucleate boiling promoted by a larger saturated pressure, a larger heat flux and a smaller diameter is dominant in small channels; convective boiling improved by a larger mass flux and a larger vapor quality is more significant in conventional channels. The HTC increases with pressure both in conventional and small channels. The HTC in conventional channels rises when mass flux increases but remains almost unaffected in small channels. A larger heat flux leads to the HTC growth in small channels and an increase of HTC was observed in conventional channels at a higher vapor quality. HTC increases inversely with diameter before dry out.
Jing Li,Yuan-ying Qiu,Hai-dong Wang,Zhao-xi Wang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6
In order to derive a method for estimating the strength coeffi cient and strain hardening exponent of steel, the performance parameters of 86 kinds of steel taken from American Iron and Steel Institute (AISI) Bar Steel Fatigue Database were examined and equations that related the strength coeffi cient and strain hardening exponent to the ultimate tensile strength and yield strength were developed. Correlations from the literature among the strength coeffi cient, strain hardening exponent and other monotonic tensile properties were also examined and compared to the relationships proposed in this study using the data of 86 kinds of steel. The proposed method was shown to be better used to estimate the strength coeffi cient and strain hardening exponent.
Jing Chen,Ji-Qing Qiu,Peng Shi,Hong-Jiu Yang 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.2
In this paper, the problem of stochastic robust stability of time-varying delay neutral system with Markovian jump parameters is investigated. The jumping parameters are considered as a continuous-time, continuous state Markov process. Based on the Lyapunov-Krasovskii functional approach, a new delay-dependent stochastic stability criteria is presented in terms of LMIs. A numerical example is given to illustrate the effectiveness of the developed method.
Measure Synchronization in a Huygens’s Non-Dissipative Two-Pendulum Clocks System
Jing Tian,ZiChen Chen,HaiBo Qiu,XiaoQiang Xi 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.2
In this paper, we characterize measure synchronization (MS) in a four-degrees-of-freedom Huygens’s two-pendulum clocks system. The two-pendulum clocks are connected by a massless spring with stiffness constant k. We find that with the stiffness constant k increasing, the coupled pendulums system achieves MS above a threshold value of kc. The energy characteristics of measure synchronization have been discussed, it is found that averaged energy of each pendulum system provide us an easy way to characterize MS transition. Furthermore, we discuss the dependence of the critical value for MS transition on initial conditions and the characteristic parameters of the system.
Instantaneous frequency extraction in time-varying structures using a maximum gradient method
Jing-liang Liu,Xiaojun Wei,Ren-Hui Qiu,Jin-Yang Zheng,Yan-Jie Zhu,Irwanda Laory 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.3
A method is proposed for the identification of instantaneous frequencies (IFs) in time-varying structures. The proposed method combines a maximum gradient algorithm and a smoothing operation. The maximum gradient algorithm is designed to extract the wavelet ridges of response signals. The smoothing operation, based on a polynomial curve fitting algorithm and a threshold method, is employed to reduce the effects of random noises. To verify the effectiveness and accuracy of the proposed method, a numerical example of a signal with two frequency modulated components is investigated and an experimental test on a steel cable with time-varying tensions is also conducted. The results demonstrate that the proposed method can extract IFs from the noisy multi-component signals and practical response signals successfully. In addition, the proposed method can provide a better IF identification results than the standard synchrosqueezing wavelet transform.
Qiu-Yan Chen,Qing-Nan Tang,Lin-Quan Tang,Wen-Hui Chen,Shan-Shan Guo,Li-Ting Liu,Chao-Feng Li,Yang Li,Yu-Jing Liang,Xue-Song Sun,Ling Guo,Hao-Yuan Mo,Rui Sun,Dong-Hua Luo,Yu-Ying Fan,Yan He,Ming-Yuan C 대한암학회 2018 Cancer Research and Treatment Vol.50 No.3
Purpose The measuring Epstein-Barr virus (EBV) DNA is an important predictor of nasopharyngeal carcinoma (NPC). This study evaluated the predictive value of pretreatment serum amyloid A (SAA) and C-reactive protein (CRP) comparing with EBV DNA in patients with NPC. Materials and Methods In an observational study of 419 non-metastatic NPC patients, we prospectively evaluated the prognostic effects of pretreatment SAA, CRP, and EBV DNA on survival. The primary endpoint was progress-free survival (PFS). Results The median level of SAA and CRP was 4.28 mg/L and 1.88 mg/L, respectively. For the high- SAA group (> 4.28 mg/L) versus the low-SAA ( 4.28 mg/L) group and the high-CRP group (> 1.88 mg/L) versus the low-CRP ( 1.88 mg/L) group, the 5-year PFS was 64.5% versus 73.1% (p=0.013) and 65.2% versus 73.3% (p=0.064), respectively. EBV DNA detection showed a superior predictive result, the 5-year PFS in the EBV DNA 1,500 copies/mL group was obviously different than the EBV DNA < 1,500 copies/mL group (62.2% versus 77.8%, p < 0.001). Multifactorial Cox regression analysis confirmed that in the PFS, the independent prognostic factors were including EBV DNA (hazard ratio [HR], 1.788; p=0.009), tumour stage (HR, 1.903; p=0.021), and node stage (HR, 1.498; p=0.049), but the SAA and CRP were not included in the independent prognostic factors. Conclusion The results of SAA and CRP had a certain relationship with the prognosis of NPC, and the prognosis of patients with high level of SAA and CRP were poor. However, the predictive ability of SAA and CRP was lower than that of EBV DNA.
Antiblurry Dejitter Image Stabilization Method of Fuzzy Video for Driving Recorders
( Jing-ying Xiong ),( Ming Dai ),( Chun-lei Zhao ),( Ruo-qiu Wang ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.6
Video images captured by vehicle cameras often contain blurry or dithering frames due to inadvertent motion from bumps in the road or by insufficient illumination during the morning or evening, which greatly reduces the perception of objects expression and recognition from the records. Therefore, a real-time electronic stabilization method to correct fuzzy video from driving recorders has been proposed. In the first stage of feature detection, a coarse-to-fine inspection policy and a scale nonlinear diffusion filter are proposed to provide more accurate keypoints. Second, a new antiblurry binary descriptor and a feature point selection strategy for unintentional estimation are proposed, which brought more discriminative power. In addition, a new evaluation criterion for affine region detectors is presented based on the percentage interval of repeatability. The experiments show that the proposed method exhibits improvement in detecting blurry corner points. Moreover, it improves the performance of the algorithm and guarantees high processing speed at the same time.