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Experimental axial force identification based on modified Timoshenko beam theory
Li, Dong-sheng,Yuan, Yong-qiang,Li, Kun-peng,Li, Hong-nan Techno-Press 2017 Structural monitoring and maintenance Vol.4 No.2
An improved method is presented to estimate the axial force of a bar member with vibrational measurements based on modified Timoshenko beam theory. Bending stiffness effects, rotational inertia, shear deformation, rotational inertia caused by shear deformation are all taken into account. Axial forces are estimated with certain natural frequency and corresponding mode shape, which are acquired from dynamic tests with five accelerometers. In the paper, modified Timoshenko beam theory is first presented with the inclusion of axial force and rotational inertia effects. Consistent mass and stiffness matrices for the modified Timoshenko beam theory are derived and then used in finite element simulations to investigate force identification accuracy under different boundary conditions and the influence of critical axial force ratio. The deformation coefficient which accounts for rotational inertia effects of the shearing deformation is discussed, and the relationship between the changing wave speed and the frequency is comprehensively examined to improve accuracy of the deformation coefficient. Finally, dynamic tests are conducted in our laboratory to identify progressive axial forces of a steel plate and a truss structure respectively. And the axial forces identified by the proposed method are in good agreement with the forces measured by FBG sensors and strain gauges. A significant advantage of this axial force identification method is that no assumption on boundary conditions is needed and excellent force identification accuracy can be achieved.
Wind-rain-induced vibration test and analytical method of high-voltage transmission tower
Li, Hong-Nan,Tang, Shun-Yong,Yi, Ting-Hua Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.4
A new computational approach for the rain load on the transmission tower is presented to obtain the responses of system subjected to the wind and rain combined excitations. First of all, according to the similarity theory, the aeroelastic modeling of high-voltage transmission tower is introduced and two kinds of typical aeroelastic models of transmission towers are manufactured for the wind tunnel tests, which are the antelope horn tower and pole tower. And then, a formula for the pressure time history of rain loads on the tower structure is put forward. The dynamic response analyses and experiments for the two kinds of models are carried out under the wind-induced and wind-rain-induced actions with the uniform and turbulent flow. It has been shown that the results of wind-rain-induced responses are bigger than those of only wind-induced responses and the rain load influence on the transmission tower can't be neglected during the strong rainstorm. The results calculated by the proposed method have a good agreement with those by the wind tunnel test. In addition, the wind-rain-induced responses along and across the wind direction are in the same order of response magnitude of towers.
Wind-rain-induced vibration test and analytical method of high-voltage transmission tower
Hong-Nan Li,Shun-Yong Tang,Ting-Hua Yi 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.48 No.4
A new computational approach for the rain load on the transmission tower is presented to obtain the responses of system subjected to the wind and rain combined excitations. First of all, according to the similarity theory, the aeroelastic modeling of high-voltage transmission tower is introduced and two kinds of typical aeroelastic models of transmission towers are manufactured for the wind tunnel tests, which are the antelope horn tower and pole tower. And then, a formula for the pressure time history of rain loads on the tower structure is put forward. The dynamic response analyses and experiments for the two kinds of models are carried out under the wind-induced and wind-rain-induced actions with the uniform and turbulent flow. It has been shown that the results of wind-rain-induced responses are bigger than those of only wind-induced responses and the rain load influence on the transmission tower can‟t be neglected during the strong rainstorm. The results calculated by the proposed method have a good agreement with those by the wind tunnel test. In addition, the wind-rain-induced responses along and across the wind direction are in the same order of response magnitude of towers.
Reviews on innovations and applications in structural health monitoring for infrastructures
Li, Hong-Nan,Yi, Ting-Hua,Ren, Liang,Li, Dong-Sheng,Huo, Lin-Sheng Techno-Press 2014 Structural monitoring and maintenance Vol.1 No.1
The developments and implementations of the structural health monitoring (SHM) system for large infrastructures have been gradually recognized by researchers, engineers and administrative authorities in the last decades. This paper summarizes an updated review on innovations and applications in SHM for infrastructures carried out by researchers at Dalian University of Technology. Invented sensors and data acquisition system are firstly briefly described. And then, some proposed theories and methods including the sensing technology, sensor placement method, signal processing and data fusion, system identification and damage detection are discussed in details. Following those, the activities on the standardization of SHM and several case applications on specific types of structure are reviewed. Finally, existing problems and promising research efforts in the field of SHM are given.
Structural health monitoring of innovative civil engineering structures in Mainland China
Li, Hong-Nan,Li, Dong-Sheng,Ren, Liang,Yi, Ting-Hua,Jia, Zi-Guang,LI, Kun-Peng Techno-Press 2016 Structural monitoring and maintenance Vol.3 No.1
This paper describes the backgrounds, motivations and recent history of structural health monitoring (SHM) developments to various types of engineering structures. Extensive applications of SHM technologies in bridges, high-rise buildings, sport avenues, offshore platforms, underground structures, dams, etc. in mainland China are summarily categorized and listed in tables. Sensors used in implementations, their deployment, damage identification strategies if applicable, preliminary monitoring achievements and experience are presented in the lists. Finally, existing problems and promising research efforts in civil SHM are discussed, highlighting challenges and future trends.
Li, Zheng,Zhang, Li-Juan,Zhang, Hong-Ru,Tian, Gao-Fei,Tian, Jun,Mao, Xiao-Li,Jia, Zheng-Hu,Meng, Zi-Yu,Zhao, Li-Qing,Yin, Zhi-Nan,Wu, Zhen-Zhou Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13
Tumors have evolved numerous mechanisms by which they can escape from immune surveillance. One of these is to produce immunosuppressive cytokines. Transforming growth factor-${\beta}$(TGF-${\beta}$) is a pleiotropic cytokine with a crucial function in mediating immune suppression, especially in the tumor microenvironment. TGF-${\beta}$ produced by T cells has been demonstrated as an important factor for suppressing antitumor immune responses, but the role of tumor-derived TGF-${\beta}$ in this process is poorly understood. In this study, we demonstrated that knockdown of tumor-derived TGF-${\beta}$ using shRNA resulted in dramatically reduced tumor size, slowing tumor formation, prolonging survival rate of tumor-bearing mice and inhibiting metastasis. We revealed possible underlying mechanisms as reducing the number of myeloid-derived suppressor cells (MDSC) and $CD4^+Foxp3^+$ Treg cells, and consequently enhanced IFN-${\gamma}$ production by CTLs. Knockdown of tumor-derived TGF-${\beta}$ also significantly reduced the conversion of na$\ddot{i}$ve $CD4^+$ T cells into Treg cells in vitro. Finally, we found that knockdown of TGF-${\beta}$ suppressed cell migration, but did not change the proliferation and apoptosis of tumor cells in vitro. In summary, our study provided evidence that tumor-derived TGF-${\beta}$ is a critical factor for tumor progression and evasion of immune surveillance, and blocking tumor-derived TGF-${\beta}$ may serve as a potential therapeutic approach for cancer.
Da-Hong Li,Jia Guo,Wen Bin,Nan Zhao,Kai-bo Wang,Jian-yong Li,Zhan-Lin Li,Hui-Ming Hua 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.7
Two novel rare chloro-containing benzylisoquinolinealkaloids, thalfoliolosumines A (1) and B (2),along with eight known isoquinoline alkaloids (3–10) wereisolated from the whole plant of Thalictrum foliolosum. The structures of these compounds were elucidated byspectral analyses, including 1D and 2D NMR (COSY,HSQC, HMBC and NOESY) experiments. The antiproliferativeeffects of all the isolated compounds were evaluatedby MTT method against MCF-7, PC-3, and U937cells, and trypan blue method against HL-60 cells. Newcompounds 1 and 2 exhibited moderate in vitro antiproliferativeactivity against MCF-7, PC-3, and HL-60 cells,and good inhibitory effects against U937 cells with IC50values of 7.50 and 6.97 μM, respectively. Compounds 7and 10 showed the strongest in vitro antiproliferative withIC50 values of 0.93 and 1.69 lM against HL-60 cell line. The antioxidant properties were also measured, bisbenzyltetrahydroisoquinolinealkaloids 3–6 showed the strongestantioxidant activities in ABTS assay.
Lu-Xi Li,Hong-Nan Li,Chao Li 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6
Residual deformation is a crucial index that should be paid special attention in the performance-based seismic analyses of reinforced concrete (RC) structures. Owing to their superior re-centering capacity under earthquake excitations, the post-tensioned self-centering (PTSC) RC frames have been proposed and developed for engineering application during the past few decades. This paper presents a comprehensive assessment on the seismic fragility of a PTSC frame by simultaneously considering maximum and residual deformations. Bivariate limit states are defined according to the pushover analyses for maximum deformations and empirical judgments for residual deformations. Incremental Dynamic Analyses (IDA) are conducted to derive the probability of exceeding predefined limit states at specific ground motion intensities. Seismic performance of the PTSC frame is compared with that of a conventional monolithic RC frame. The results show that, taking a synthetical consideration of maximum and residual deformations, the PTSC frame surpasses the monolithic frame in resisting most damage states, but is more vulnerable to ground motions with large intensities.
Zhi-Ning Huang,Han Liang,Hong Qiao,Bao-Rui Wang,Ning Qu,Hua Li,Run-Run Zhou,Li-Juan Wang,Shan-Hua Li,Fu-Nan Li 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.12
Guided by bioisosterism and pharmacokinetic parameters, we designed and synthesized a series of novel benzamide derivatives. Preliminary in vitro studies indicated that compounds 10b and 10j show significant inhibitory bioactivity in HepG2 cells (IC50 values of 0.12 and 0.13 μM, respectively). Compounds 10b and 10j induced the expression of HIF-1α protein and downstream target gene p21, and upregulated the expression of cleaved caspase-3 to promote tumor cells apoptosis.