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Behaviors of UHPC-filled Q960 high strength steel tubes under lowtemperature compression
Jia-Bao Yan,Shunnian Hu,Yan-Li Luo,Xuchuan Lin,Yun-Biao Luo,Lingxin Zhang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.2
This paper firstly proposed high performance composite columns for cold-region infrastructures using ultra-high performance concrete (UHPC) and ultra-high strength steel (UHSS) Q960E. Then, 24 square UHPC-filled UHSS tubes (UHSTCs) at low temperatures of -80, -60, -30, and 30℃ were performed under axial loads. The key influencing parameters on axial compression performance of UHSS were studied, i.e., temperature level and UHSS-tube wall thickness (t). In addition, mechanical properties of Q960E at low temperatures were also studied. Test results revealed low temperatures improved the yield/ultimate strength of Q960E. Axial compression tests on UHSTCs revealed that the dropping environmental temperature increased the compression strength and stiffness, but compromised the ductility of UHSTCs; increasing t significantly increased the strength, stiffness, and ductility of UHSTCs. This study developed numerical and theoretical models to reproduce axial compression performances of UHSTCs at low temperatures. Validations against 24 tests proved that both two methods provided reasonable simulations on axial compression performance of UHSTCs. Finally, simplified theoretical models (STMs) and modified prediction equations in AISC 360, ACI 318, and Eurocode 4 were developed to estimate the axial load capacity of UHSTCs at low temperatures.
Jia-Yu Lv,Ning-Ning Zhang,Ya-Wei Du,Ying Wu,Tian-Qiang Song,Ya-Min Zhang,Yan Qu,Yu-Xin Liu,Jie Gu,Ze-Yu Wang,Yi-Bo Qiu,Bing Yang,Da-Zhi Tian,Qing-Jun Guo,Li Zhang,Ji-San Sun,Yan Xie,Zheng-Lu Wang,Xin 연세대학교의과대학 2021 Yonsei medical journal Vol.62 No.1
Purpose: The aim of this study was to compare the efficacy of liver transplantation (LT) and liver resection (LR) for hepatocellularcarcinoma (HCC) patients with portal vein tumor thrombus (PVTT) and to investigate risk factors affecting prognosis. Materials and Methods: A total of 94 HCC patients with PVTT type I (segmental PVTT) and PVTT type II (lobar PVTT) were involvedand divided into LR (n=47) and LT groups (n=47). Recurrence-free survival (RFS) and overall survival (OS) were comparedbefore and after inverse probability of treatment weighting (IPTW). Prognostic factors for RFS and OS were explored. Results: Two treatment groups were well-balanced using IPTW. In the entire cohort, LT provided a better prognosis than LR. Among patients with PVTT type I, RFS was better with LT (p=0.039); OS was not different significantly between LT and LR(p=0.093). In subgroup analysis of PVTT type I patients with α-fetoprotein (AFP) levels >200 ng/mL, LT elicited significantly longermedian RFS (18.0 months vs. 2.1 months, p=0.022) and relatively longer median OS time (23.6 months vs. 9.8 months, p=0.065). Among patients with PVTT type II, no significant differences in RFS and OS were found between LT and LR (p=0.115 and 0.335,respectively). Multivariate analyses showed treatment allocation (LR), tumor size (>5 cm), AFP and aspartate aminotransferase(AST) levels to be risk factors of RFS and treatment allocation (LR), AFP and AST as risk factors for OS. Conclusion: LT appeared to afford a better prognosis for HCC with PVTT type I than LR, especially in patients with AFP levels>200 ng/mL.
Output Feedback Stabilization for an ODE Coupled with a Wave Equation with Variable Coefficients
Yan Xing Zhao,Jun Jun Liu,Yan Na Jia 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2
In this paper, we are concerned with the output feedback problem for coupled ODE-wave systems subject to spatially-varying coefficients. An original transformation is designed to turn the wave equation into an equation of the same type with constant coefficient and low order term. Taking advantage of the backstepping method, a state observer is constructed by non-collocated boundary displacement and velocity measurement. Output feedback on the based of the observer output feedback is then constructed, which makes use of the backstepping method to make the system exponentially stable. Finally, we demonstrate the well-posed and the exponential stability of the closed-loop system.
Ketamine induces neuronal apoptosis and cognitive disorder via miR-199a-5p/HIF-1α in neonatal rats
Jia Yan,Yue Yu,Yu Sun,Rong Hu,Hong Jiang 대한독성 유전단백체 학회 2017 Molecular & cellular toxicology Vol.13 No.4
It reported that repeated administration of clinical doses of ketamine could induce neuronal apoptosis in the immature brain. In this study, SpragueDawley postnatal day 7 rats were treated with ketamine. As the rats grew, we found ketamine impaired the cognitive function of the rats. Ketamine increased HIF1α level in the brain tissues of rats as compared to the control group and YC-1 rescued those effects. The escape latency and the platform crossing time of Morris water maze decreased in the YC-1-treated rats compared to the control in ketamine-treated rats. We also found that ketamine decreased the expression of miR199a-5p and HIF-1α is a directly target of miR-199a5p. Administration of ketamine also decrease the cell activity while YC-1 and MiR-199a-5p mimics rescued the inhibition effect. In conclusion, we suggest that ketamine-induced neuronal apoptosis in neonatal rats, followed by learning and memory impairment, might be mediated via the miR-199a-5p/HIF-1α signalling pathway.
Jia-Bao Yan,J.Y. Richard Liew,Min-Hong Zhang 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.4
Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of 1,450 kg/㎥ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. This paper investigates the structural performances of SCS sandwich composite beams with ULCC as filled material. Overlapped headed shear studs were used to provide shear and tensile bond between the face plate and the lightweight core. Three-dimensional nonlinear finite element (FE) model was developed for the ultimate strength analysis of such SCS sandwich composite beams. The accuracy of the FE analysis was established by comparing the predicted results with the quasi-static tests on the SCS sandwich beams. The FE model was also applied to the nonlinear analysis on curved SCS sandwich beam and shells and the SCS sandwich beams with J-hook connectors and different concrete core including ULCC, lightweight concrete (LWC) and normal weight concrete (NWC). Validations were also carried out to check the accuracy of the FE analysis on the SCS sandwich beams with J-hook connectors and curved SCS sandwich structure. Finally, recommended FE analysis procedures were given.
Developments of double skin composite walls using novel enhanced C-channel connectors
Jia-Bao Yan,An-Zhen Chen,Tao Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.6
The developments of double skin composite (DSC) walls with novel enhanced C-channel connectors (DSCW-EC) were reported. Followed axial compression tests on prototype walls were carried to evaluate structural performances of this novel DSC composite structures. The testing program consists of five specimens and focused on the layout of the novel enhanced C-channel (EC) connectors, which include the web direction of C-channels, steel-faceplate thickness, vertical and horizontal spacing of Cchannels. Crushing in concrete core and buckling of steel faceplate were two main observed failed modes from the compression tests. However, elastic or plastic buckling of the steel faceplate varies with designed parameters in different specimens. The influences of those investigated parameters on axial compressive behaviors of DSCW-ECs were analyzed and discussed. Recommendations on the layout of novel EC connectors were then given based on these test results and discussions. This paper also developed analytical models for predictions on ultimate compressive resistance of DSCW-ECs. Validation against the reported test results show that the developed theoretical models predict well the ultimate compressive resistance of DSCW-ECs.
Tensile behavior of stainless steel S30408 at the Arctic low temperature
Jia-Bao Yan,Zhicheng Lin,Peng Xie,Yun-Biao Luo,Yanbo Li 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5
This paper investigated tensile behaviours of S30408 at the Arctic low temperatures (T) of -80~20℃. A cooling chamber equipped with liquid nitrogen gas was adopted to rebuild the Arctic low-temperature environment. Standard tension tests were performed on 48 coupons with different thickness at different T values of -80, -60, -30, and 20℃. Test results revealed the ductile failure mode of stainless steel S30408 even at -80℃. The tensile stress-strain (σ-ε) curves of S30408 at ambient temperatures exhibited a long strain hardening plateau. Meanwhile, the low-temperature tensile σ-ε curves of S30408 were different from those at ambient temperatures, which exhibited a second hardening stage with a larger slope than the first hardening. The decreasing T generally increased the elastic modulus, yield and ultimate strength, but reduced the ductility of S30408. Decreasing the T from 20 to -80℃ reduced the ductility of S30408 by about 28%, but improved the elastic modulus, yield and ultimate strength by about 20%, 22%, and 75%, respectively. This paper also adopted the best subset regression analysis method to develop empirical formulae on estimating influences of T on mechanical properties of S30408. Validations of the predictions by these empirical formulae against the test results in the literature proved their accuracies.
Shear and tensile behaviors of headed stud connectors in double skin composite shear wall
Jia-Bao Yan,Zhe Wang,Tao Wang,Xiao-Ting Wang 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.6
This paper studies shear and tensile behaviors of headed stud connectors in double skin composite (DSC) structure. Firstly, 11 push-out tests and 11 tensile tests were performed to investigate the ultimate shear and tensile behaviors of headed stud in DSC shear wall, respectively. The main parameters investigated in this test program were height and layout of headed stud connectors. The test results reported the representative failure modes of headed studs in DSC structures subjected to shear and tension. The shear-slip and tension-elongation behaviors of headed studs in DSC structures were also reported. Influences of different parameters on these shear-slip and tension-elongation behaviors of headed studs were discussed and analyzed. Analytical models were also developed to predict the ultimate shear and tensile resistances of headed stud connectors in DSC shear walls. The developed analytical model incorporated the influence of the dense layout of headed studs in DSC shear walls. The validations of analytical predictions against 22 test results confirmed the accuracy of developed analytical models.