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RISS 인기검색어
- 검색키워드
- 저자 : Haiwang Li (검색결과 4 건)
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Experimental Study on the Ultralow Cycle Fatigue Performance of Bolted Spherical Joint Specimens
Yanying Li,Haiwang Li,Pengliang Liang,Xingyu Wang 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.3
Under disastrous earthquake conditions, the bolted spherical joints in spatial steel grid structures are prone to bending, breaking, and other failure modes, and their failure has obvious ultralow cycle fatigue failure characteristics. In this paper, quasistatic tests were carried out on three groups (nine specimens in total) of bolted spherical joints with joints at both ends under uniaxial cyclic loading. The failure characteristics, hysteretic behaviour, bearing capacity degradation, stiffness degradation, and energy compression capacity of bolted spherical joints under three loading schemes were studied. At the same time, the change rule of the rotation angle with the number of cycles was obtained. The experimental study shows that each member experiences characteristic moments of high-strength bolt bending, cracking, crack propagation, and a loud crack and that bolt failure occurs at the middle bolt ball connection. The ultimate ultralow cycle fatigue failure of the specimen occurs after more than 10 cycles, and the energy compression capacity is poor due to the small volume of high-strength bolts and sleeves. The "pinching phenomenon" of the hysteresis curve of the bolted spherical joint is serious. The tension area of the hysteresis curve increases, and the fullness of the compression area decreases, with increasing tensile amplitude. Based on the cumulative energy compression, a damage model suitable for bolted spherical joints under cyclic loading is proposed. From the experimental data, a correlation formula between the angle change rate and the damage model was established when the middle bolt ball of the connection specimen experienced a tension–compression cyclic load. This formula provides a reference for the evaluation of bolted spherical joints of bolt ball grid structures after an earthquake.
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Dasheng Li,Dawei Wang,Jianping Dong,Nana Wang,He Huang,Haiwang Xu,Chen Xia 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.4
The epidemic of 2019 novel coronavirus, later named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is still gradually spreading worldwide. The nucleic acid test or genetic sequencing serves as the gold standard method for confirmation of infection, yet several recent studies have reported false-negative results of real-time reverse-transcriptase polymerase chain reaction (rRT-PCR). Here, we report two representative false-negative cases and discuss the supplementary role of clinical data with rRT-PCR, including laboratory examination results and computed tomography features. Coinfection with SARS-COV-2 and other viruses has been discussed as well.
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Hai Wang,Jie Li,Yuchen Song 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3
A numerical investigation is presented in this paper on partially encased composite (PEC) columns subjected to eccentric loading. 3D fi nite element (FE) models were established based on the dynamic explicit method, which were validated by comparing the FE outcomes with some available test results in previous literature. Using the verifi ed model, a parametric study was conducted to investigate the eff ects of several factors on the strength and behaviors of PEC columns, including the concrete strength, the steel yield strength, and the load eccentricity. The outcomes of the FE analyses, together with the test results reported in previous studies, were compared with the capacities predicted by the current design codes for eccentrically loaded PEC columns. It was found that the existing design methods with the assumption of rectangular stress blocks (fully plastic assumption) could be unconservative in some circumstances. Therefore, a modifi ed partially plastic design approach was proposed based on the Eurocode 4 design method, which was confi rmed to be conservative yet economic in predicting the interactive force–moment (N–M) capacity of PEC columns under eccentric compression.
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Neutrophils as a Protagonist and Target in Chronic Rhinosinusitis
Hai Wang,Li Pan,Zheng Liu 대한이비인후과학회 2019 Clinical and Experimental Otorhinolaryngology Vol.12 No.4
Neutrophils have traditionally been acknowledged as the first immune cells that are recruited to inflamed tissues during acute inflammation. By contrast, their importance in the context of chronic inflammation has been studied in less depth. Neutrophils can be recruited and are largely present in the nasal mucosa of patients with chronic rhinosinusitis (CRS) both in Asians and in Caucasians. Increased infiltration of neutrophils in patients with CRS has been linked to poor corticosteroid response and disease prognosis. Meanwhile, tissue neutrophils may possess specific phenotypic features distinguishing them from resting blood counterparts and are endowed with particular functions, such as cytokines and chemokines production, thus may contribute to the pathogenesis of CRS. This review aims to summarize our current understanding of the pathophysiologic mechanisms of CRS, with a focus on the roles of neutrophils. We discuss recruitment, function, and regulation of neutrophils in CRS and outline the potential therapeutic strategies targeting neutrophils.
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