Blasting wave pattern recognition based on Hilbert-Huang transform

Li, Xuelong,Wang, Enyuan,Li, Zhonghui,Bie, Xiaofei,Chen, Liang,Feng, Junjun,Li, Nan Techno-Press 2016 Geomechanics & engineering Vol.11 No.5

Rockburst is becoming more serious in Chinese coal mine. One of the effective methods to control rockburst is blasting. In the paper, we monitored and analyzed the blasting waves at different blast center distances by the Hilbert-Huang transform (HHT) in a coal mine. Results show that with the increase of blast center distance, the main frequency and amplitude of blasting waves show the decreasing trend. The attenuation of blasting waves is slower in the near blast field (10-75 m), compared with the far blast field (75-230 m). Besides, the frequency superposition phenomenon aggravates in the far field. A majority of the blasting waves energy at different blast center distances is concentrated around the IMF components 1-3. The instantaneous energy peak shows attenuation trend with the blast center distance increase, there are two obvious energy peaks in the near blast field (10-75 m), the energy spectrum appears "fat", and the total energy is greater. By contrast, there is only an energy peak in the far blast field, the energy spectrum is "thin", and the total energy is lesser. The HHT three dimensional spectrum shows that the wave energy accumulates in the time and frequency with the increasing of blast center distance.

The Benefits of Indirect Exposure to Trauma

Xiaofei Kang,Yueyan Fang,Sihan Li,Yadong Liu,Di Zhao,Xiujuan Feng,Yaqi Wang,Ping Li 대한신경정신의학회 2018 PSYCHIATRY INVESTIGATION Vol.15 No.5

Objective Ambulance personnel who witness trauma experienced by patients have been reported to experience positive changes, known as vicarious posttraumatic growth (VPTG). We examined VPTG and its relationship with social support and resilience among ambulance personnel. Methods The sample (n=227) was recruited from six emergency centers in China. The measures included the Posttraumatic Growth Inventory (PTGI), the Social Support Rating Scale (SSRS), and the 10-item Connor-Davidson Resilience Scale (CD-RISC-10). Structure Equation Modeling (SEM) and the bootstrapping procedure were used to examine indirect effects. Results The participants’ mean score for VPTG was 68.96 (SD=15.51). Social support had significant direct effects on resilience (β=0.51, p<0.001) and VPTG (β=0.25, p=0.001), and resilience (β=0.58, p<0.001) had a significant direct effect on VPTG. Furthermore, social support had a significant indirect effect (0.51×0.58=0.30, p<0.001) on VPTG through resilience. Conclusion Although the nature of the work of ambulance personnel is not expected to change, the negative effects of the trauma they encounter can be reduced by providing them with more support resources and interventions to foster their resilience, which in turn, promote VPTG.

Kano Model Analysis Required in APP Interactive Design based on Mobile User Experience

Xiaofei Li,Yue You 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.11

The user experience in APP interactive designdraws more and more attention in the APP market where the user population expands continuously and the competition becomes increasingly intense, butcurrent studies mostly focus on the user website experience. This paper is intended to classify and study user needs in APP interactive design based on Kano model and Better-Worse coefficient, and gain Kano two-dimensional attribute classification of user needsin the design. In addition, it carries out analysis on these needs based on the better-worse coefficient.

A BIM Based Approach for Structural Health Monitoring of Bridges

Xiaofei Li,Yuyu Xiao,Hainan Guo,Jisong Zhang 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.1

With the development of bridges, independent condition assessment of large-scale bridges has garnered significant attention over the past few decades. Data-driven structural health monitoring (SHM) techniques offer valuable information on the existing health of the structures, maintain safety, and uninterrupted use under varied operational conditions by undertaking timely risk and hazard mitigation. Traditional approaches, however, are not enough to monitor a large amount of SHM data and conduct systematic decision making for future maintenance. In this paper, a bridge health monitoring system is developed through the combination of building information modeling (BIM) and traditional bridge health monitoring that can organize and visualize a considerable amount of sensor data and subsequent structural health information over a prolonged period. The system can identify the structural damage by evaluating the data from sensors using Wigner-Ville distribution (WVD) in bilinear time-frequency analysis. A BIM-enabled platform is utilized to develop the proposed visualization tool for a long-span bridge and enable automated sensor data inventory into the BIM environment. The system has been tested for its robustness and functionality against the development requirements, and the results showed promising potential to support more effective bridge information management.

Asymptotic analysis of the narrow escape problem in dendritic spine shaped domain: three dimensions

Li, Xiaofei,Lee, Hyundae,Wang, Yuliang IOP 2017 JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL Vol.50 No.32

<P>This paper deals with the three-dimensional narrow escape problem in a dendritic spine shaped domain, which is composed of a relatively big head and a thin neck. The narrow escape problem is to compute the mean first passage time of Brownian particles traveling from inside the head to the end of the neck. The original model is to solve a mixed Dirichlet–Neumann boundary value problem for the Poisson equation in the composite domain, and is computationally challenging. In this paper we seek to transfer the original problem to a mixed Robin–Neumann boundary value problem by dropping the thin neck part, and rigorously derive the asymptotic expansion of the mean first passage time with high order terms. This study is a nontrivial three-dimensional generalization of the work in Li (2014 <I>J. Phys. A: Math. Theor</I>. <B>47</B> 505202), where a two-dimensional analogue domain is considered.</P>

화장품 쇼핑가치가 쇼핑행동에 미치는 영향 연구: 중국인 관광객을 중심으로

이효비 ( Xiaofei Li ),김정아 ( Chung Ah Kim ) 대한관광경영학회 2016 觀光硏究 Vol.31 No.2

본 연구는 새로이 각광받고 있는 쇼핑관광의 관점에서 중국인 관광객의 한국화장품 쇼핑행동에 영향을 미치는 쇼핑가치에 대한 관심으로 시작되었으며, 특히 한류에 대한 호감도가 한국화장품과 같은 한국제품의 판매에 영향을 줄 수 있으므로 한류호감도의 조절효과에 대해 알아보고자 하였다. 분석결과는 첫째, 중국인 관광객들의 쇼핑가치 중에 미적 가치, 쾌락적 가치 및 실용적 가치는 화장품 쇼핑행동에 긍정적인 영향을 미치고 있는 것으로 나타났다. 둘째, 미적가치와 한류광고의 상호작용은 화장품 쇼핑행동에 부(-)의 조절효과가 나타났으며, 한류 컨텐츠와 쾌락적 가치의 상호작용 또한 부(-)의 조절효과가 있는 것으로 나타났으며, 한류 컨텐츠와 시각적 가치의 상호작용은 화장품 쇼핑행동에 정(+)의 조절효과가 있는 것으로 나타났다. The purpose of this research was to analyze the effects of shopping value on the shopping behavior and the moderating effect of KoreanWave. The results were as follows: (1) Shopping values of Chinese tourists had significant effects on the cosmetic shopping behavior. Beauty value hedonic value and practical value were found to have positive effects on the cosmetic shopping behavior. (2) Korean wave contents and Korean wave advertisement were found to have significant moderating effects on the relationship between the shopping value and the shopping behavior. Specifically, the interaction of beauty value and Korean wave advertisement had a negative moderating effect; the interaction of hedonic value and Korean wave contents had a negative moderating effect; the interaction of visible value and Korean wave contents had a positive moderating effect.

Observer-based Composite Adaptive Dynamic Terminal Sliding-mode Controller for Nonlinear Uncertain SISO Systems

Xiaofei Liu,Shengbo Qi,Reza Malekain,Zhixiong Li 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.1

In the present paper, the observer-based composite adaptive terminal sliding-mode control is investigatedfor the nonlinear uncertain system. First, an adaptive observer is designed to estimate the unavailable high-orderderivative of the output. Then, a new dynamic terminal sliding surface is proposed with a state filter, which aims todevelop the dynamic terminal sliding mode controller. By the composite adaptive control methods, a new adaptivelaw is designed, and the stability of the overall system is proofed based on the Lyapunov method. Finally, somenumerical simulations are conducted to validate the effectiveness of the proposed algorithm.

A Simple and Fast Action Recognition Method Based on AdaBoost Algorithm

Xiaofei Ji,Lu Zhou,Ningli Qin,Yibo Li 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.8

A novel feature representation method based on AdaBoost algorithm is put forward for action recognition in this paper. The method can not only adequately describe action in complex scenarios, but also select the most discriminative sample subset from a large amount of raw features of training data. So it can realize a double result, that is, reduce the recognition computational complexity and achieve a good recognition accuracy. The pyramid histogram of oriented gradient feature (PHOG) descriptor is utilized to represent raw feature data. In order to select most discriminative samples subset, AdaBoost algorithm is used to extract the raw feature data. The nearest neighbor classifier algorithm is utilized to test the proposed method on the UCF Sports database. Experiment results show that the method not only achieve the better recognition rate but also greatly improve the speed of recognition.

The Influence of Dietary Calcium and Phosphorus Imbalance on Intestinal NaPi-IIb and Calbindin mRNA Expression and Tibia Parameters of Broilers

Li, Jianhui,Yuan, Jianmin,Guo, Yuming,Sun, Qiujuan,Hu, Xiaofei Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.4

A $2{\times}2$ factorial experiment was conducted to study the effect of dietary calcium and non-phytate phosphorus (nPP) imbalance on calbindin and NaPi-IIb mRNA levels in the small intestine and tibia parameters of broiler chicks. One hundred and forty four 1-d-old Arbor Acres male broiler chicks were divided into four treatments consisted of six replicates with six chicks each. The two dietary calcium levels were 1.10% and 0.60%, and two dietary nPP levels were 0.50% and 0.27%. Results showed that a high Ca/nPP ratio diet (4.07:1) significantly depressed feed intake and weight gain of broilers (p<0.05), but a lower Ca:nPP ratio (1.2:1) had no influence (p>0.05). Low-Ca with low-P diet resulted in low tibia minerals and tibia breaking strength of broilers, and all the tibia parameters were further decreased when the dietary ratio of Ca to P was relative higher. Low dietary Ca or P up-regulated the calbindin and NaPi-IIb mRNA expression levels. Low Ca with normal P diet up-regulated duodenal calbindin mRNA expression level to the greatest extent. Low P with a normal Ca diet significantly enhanced NaPi-IIb mRNA expression level to the highest extent. These results suggest that the calbindin and NaPi-IIb mRNA expression were enhanced by the imbalance between dietary Ca and nPP, and their expression were not only influenced by Ca or nPP level, but also the ratio of Ca:nPP.

Research on Electromagnetic Effect of Irradiation on Silicon via Interconnects

Xiaofei Xu,Denghua Li 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

The paper was studied the damage effect mechanism of proton radiation on metallic interconnect, where the metal electron migration was caused by space ion irradiation. A physical transfer model of via was constructed, where the equivalent distribution parameters circuit structure was extracted. The parameters of the electromagnetic eff ect of copper via interconnects were calculated under diff erent irradiation dose rates. The study showed the result of the influence on via length of the eff ective transmission signal, the infl uence of radiation on the characteristic impedance, and the effect of radiation on the failure of via, which could provide a theoretical instruction to enhance the anti-TID ability.