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136 results on '"Zhang, Shengfei"'

10. Non-contact impact load identification based on intelligent visual sensing technology.

Author

Zhang, Shengfei, Ni, Pinghe, Wen, Jianian, Han, Qiang, Du, Xiuli, and Xu, Kun

Abstract

Accurate identification of impact loads is vital for structural assessment and design. Traditional methods rely on complex equipment, such as accelerometers or strain gauge, which can be expensive and prone to failure. This study introduces a non-contact intelligent identification approach incorporating visual sensing technology, providing a convenient means to identify impact loads. Numerical simulations explore the differences in identifying impact forces through acceleration and displacement responses, particularly by considering such variables as measurement noise and number of measurement points. A meticulously designed experiment verified the feasibility of the proposed method for measuring the displacement and velocity of rapidly moving targets, and evaluated its performance in terms of accuracy. A series of impact loading experiments were conducted on a simply supported girder bridge model to validate the effectiveness of the proposed impact force identification method. Results indicate strong agreement between displacement response measurements and percentile meters. The proposed non-contact method accurately identifies single or continuous impact loads, with a minimum peak relative error of 0.2%. This study represents a pioneering application of intelligent visual sensing technology in the field of impact load identification. Moreover, the current research introduces a novel approach to address the challenges faced by conventional methods in identifying impact loads. Future research can leverage the groundwork laid by this study to further optimize and expand the proposed method, enhancing its capabilities and fully harnessing its potential to offer advanced solutions in structural health monitoring. [ABSTRACT FROM AUTHOR]

Published
2024
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22. Slotted vertical wall for decoupling and beam tilt correction.

Author

Wang, Yiying, Zhang, Shengfei, Wang, Bo, Zhang, Hongxin, Jiang, Yannan, Pan, Wanghua, and Kishk, Ahmed A.

Subjects
ANTENNA radiation patterns, SIDING (Building materials), CONDUCTORS (Musicians), MICROSTRIP transmission lines, BANDWIDTHS
Abstract

An intra-band pattern-corrected decoupling vertical conducting wall is realized by dielectric substrate with conductor cladding on both side wall between two tightly spaced H-plane microstrip patches with λ 0/20 edge-to-edge spacing. The wall is grounded and two symmetrical slots are etched on the vertical substrate. The measured results agree with the simulations, showing that the slotted vertical wall reduces the mutual coupling within the bandwidth to −30 dB and corrects the radiation beam tilt to be within −4.5° to 3° from the broadside direction. A gain reduction of 0.6 dB is observed compared to the gain without the slotted decoupling wall. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Continuous authentication by free-text keystroke based on CNN plus RNN

Author

Zhang Shengfei, Yi Shengwei, and Lu Xiaofeng

Subjects
Authentication, InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI), Computer science, Speech recognition, ComputingMilieux_PERSONALCOMPUTING, 020206 networking & telecommunications, 02 engineering and technology, Keystroke logging, Set (abstract data type), InformationSystems_MODELSANDPRINCIPLES, Mode (computer interface), 0202 electrical engineering, electronic engineering, information engineering, Feature (machine learning), General Earth and Planetary Sciences, 020201 artificial intelligence & image processing, General Environmental Science
Abstract

Personal keystroke mode is difficult to imitate and can therefore be used for identity authentication. According to the keystroke data when a person inputs free text, the keystroke habit of the person can be learned. Detecting a user’s keystroke habits as the user enters text can continuously verify the user’s identity without affecting user input. This paper proposes to divide the user keystroke data into a fixed-length keystroke sequence, and convert the keystroke sequence into a keystroke vector sequence according to the time feature of the keystroke. A model of a recursive neural network plus a convolutional neural network is used to learn a sequence of individual keystroke vectors to obtain individual keystroke features for identity authentication. The model was tested using an open data set and the best False Rejection Rate(FRR) was 1.95%, False Acceptance Rate (FAR) was 4.12% and Equal Error Rate(EER) was 3.04%.

Published
2019

45. Unidirectional Radiation of Thin Slot Antenna on Single Substrate

Author

Yiying Wang, Weiping Cao, Ahmed A. Kishk, Guizhen Lu, and Zhang Shengfei

Subjects
Microstrip antenna, Optics, Materials science, business.industry, Order (ring theory), Slot antenna, Reflector (antenna), Substrate (electronics), Radiation, Lambda, business, Microstrip
Abstract

A novel deformed reflector very close to a narrow slot is proposed to realize unidirectional radiation. These reflectors consist of two large metal planes and are separated by one slot in order to accommodate the feed. The microstrip line feeding is adopted on a thin substrate of $\boldsymbol{\lambda}_\mathbf{{\mathrm{eff}}}/\mathbf{42}$ thickness at 5.8GHz.

Published
2020

46. Associations between VDR Gene Polymorphisms and Osteoporosis Risk and Bone Mineral Density in Postmenopausal Women: A systematic review and Meta-Analysis

Author

Zhang, Liang, Yin, Xin, Wang, Jingcheng, Xu, Daolinag, Wang, Yongxiang, Yang, Jiandong, Tao, Yuping, Zhang, Shengfei, Feng, Xinmin, and Yan, Caifeng

Subjects
musculoskeletal diseases, lcsh:R, Gene Expression, lcsh:Medicine, Middle Aged, Article, Bone and Bones, White People, Postmenopause, Retraction Note, Asian People, Bone Density, polycyclic compounds, Humans, Receptors, Calcitriol, Female, Genetic Predisposition to Disease, lipids (amino acids, peptides, and proteins), lcsh:Q, Deoxyribonucleases, Type II Site-Specific, lcsh:Science, Osteoporosis, Postmenopausal, Polymorphism, Restriction Fragment Length
Abstract

Results on the relationships between vitamin D receptor (VDR) gene polymorphisms and postmenopausal osteoporosis (PMOP) susceptibility and bone mineral density (BMD) are conflicting. The aim of the study is to identify more eligible studies that calculated pooled OR and WMD with 95% CI to assess their associations. Overall, there were significant correlations between VDR ApaI, VDR FokI and PMOP susceptibility. Subgroup analysis showed that VDR ApaI polymorphism significantly decreased the osteoporosis risk in Caucasian postmenopausal women. In Asian populations, VDR BsmI and VDR FokI were associated with an increased risk of PMOP. As to the associations between VDR polymorphisms and BMD, Caucasian PMOP women carrying the ApaI aa genotype were at risk of high BMD in femoral neck, and low femoral neck BMD was observed in Caucasian PMOP women with FokI Ff genotype. PMOP women with the Cdx2 GA genotype had a lower lumbar spine BMD in overall and Caucasian populations compared with PMOP women with GG genotype. Different VDR gene polymorphisms have different impacts on PMOP risk and BMD.

Published
2018

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