Model predictive control strategies for protection of structures during earthquakes

Long-He Xu,Zhong-Xian Li 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.2

This paper presents a theoretical study of a model predictive control (MPC) strategy employed in semi-active control system with magnetorheological (MR) dampers to reduce the responses of seismically excited structures. The MPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an objective function, which can compensate for the effect of time delay that occurred in real application. As an example, a 5-story building frame equipped with two 20 kN MR dampers is presented to demonstrate the performance of the proposed MPC scheme for addressing time delay and reducing the structural responses under different earthquakes, in which the predictive length l = 5 and the delayed time step d = 10, 20, 40, 60, 100 are considered. Comparison with passive-off, passive-on, and linear quadratic Gaussian (LQG) control strategy indicates that MPC scheme exhibits good control performance similar to the LQG control strategy, both have better control effectiveness than two passive control methods for most cases, and the MPC scheme used in semi-active control system show more effectiveness and robustness for addressing time delay and protecting structures during earthquakes.

Self-consistent Calculations of the Effects of Disorder in d-wave and s-wave Superconductors

Long-He Xu,Yun Song 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

The kernel polynomial method, as an approach to deriving highly-accurate spectral properties oflarge sparse matrices, is extended to investigate the effects of disorder in two-dimensional inhomogeneoussuperconductors. Being able to solve the Bogoliubov-de Gennes equations for quite largesquare lattices self-consistently, we gain new microscopic insights and make intuitive observationsof the localization of low-energy quasiparticles on the nanometer scale. We also compare the behaviorsof the optical conductivities of superconductors with different pairing symmetries. We findthat the Drude weight turns out to be finite only for the weakly-disordered d-wave superconductorwhile obvious suppression of the optical conductivity in the infrared range can be observed in thedisordered s-wave superconductor.

Model predictive control strategies for protection of structures during earthquakes

Xu, Long-He,Li, Zhong-Xian Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.2

This paper presents a theoretical study of a model predictive control (MPC) strategy employed in semi-active control system with magnetorheological (MR) dampers to reduce the responses of seismically excited structures. The MPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an objective function, which can compensate for the effect of time delay that occurred in real application. As an example, a 5-story building frame equipped with two 20 kN MR dampers is presented to demonstrate the performance of the proposed MPC scheme for addressing time delay and reducing the structural responses under different earthquakes, in which the predictive length l = 5 and the delayed time step d = 10, 20, 40, 60, 100 are considered. Comparison with passive-off, passive-on, and linear quadratic Gaussian (LQG) control strategy indicates that MPC scheme exhibits good control performance similar to the LQG control strategy, both have better control effectiveness than two passive control methods for most cases, and the MPC scheme used in semi-active control system show more effectiveness and robustness for addressing time delay and protecting structures during earthquakes.

Hysteretic behavior studies of self-centering energy dissipation bracing system

Long-He Xu,Xiaowei Fan,Dengcheng Lu,Zhong-Xian Li 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.6

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the selfcentering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

Seismic behavior enhancement of frame structure considering parameter sensitivity of self-centering braces

Long-He Xu,Xing-Si Xie,Xintong Yan,Zhong-Xian Li 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.71 No.1

A modified mechanical model of pre-pressed spring self-centering energy dissipation (PS-SCED) brace is proposed, and the hysteresis band is distinguished by the indication of relevant state variables. The MDOF frame system equipped with the braces is formulated in an incremental form of linear acceleration method. A multi-objective genetic algorithm (GA) based brace parameter optimization method is developed to obtain an optimal solution from the primary design scheme. Parameter sensitivities derived by the direct differentiation method are used to modify the change rate of parameters in the GA operator. A case study is conducted on a steel braced frame to illustrate the effect of brace parameters on node displacements, and validate the feasibility of the modified mechanical model. The optimization results and computational process information are compared among three cases of different strategies of parameter change as well. The accuracy is also verified by the calculation results of finite element model. This work can help the applications of PS-SCED brace optimization related to parameter sensitivity, and fulfill the systematic design procedure of PS-SCED brace-structure system with completed and prospective consequences.

Seismic response analysis of RC frame core-tube building with self-centering braces

Xu, Long-He,Xiao, Shui-Jing,Lu, Xiao Techno-Press 2018 Structural monitoring and maintenance Vol.5 No.2

This paper examines the seismic responses of a reinforced concrete (RC) frame core-tube building with pre-pressed spring self-centering energy dissipation (PS-SCED) braces. The PS-SCED brace system consists of friction devices for energy dissipation, pre-pressed combination disc springs for self-centering and tube members as guiding elements. A constitutive model of self-centering flag-shaped hysteresis for PS-SCED brace is developed to better simulate the seismic responses of the RC frame core-tube building with PS-SCED braces, which is also verified by the tests of two braces under low cyclic reversed loading. Results indicate that the self-centering and energy dissipation capabilities are well predicted by the proposed constitutive model of the PS-SCED brace. The structure with PS-SCED braces presents similar peak story drift ratio, smaller peak acceleration, smaller base shear force and much smaller residual deformations as compared to the RC frame core-tube building with bucking-restrained braces (BRBs).

Prognostic Significance of Overexpression of EZH2 and H3k27me3 Proteins in Gastric Cancer

He, Long-Jun,Cai, Mu-Yan,Xu, Guo-Liang,Li, Jian-Jun,Weng, Zi-Jin,Xu, Da-Zhi,Luo, Guang-Yu,Zhu, Sen-Lin,Xie, Dan Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.7

The enhancer of zeste homolog 2 (EZH2) methyl transferase and histone 3 lysine 27 (H3K27me3) protein can repress gene transcription, and their aberrant expression has been observed in various human cancers. This study determined their expression levels in gastric cancer tissues with reference to clinicopathological features and patient survival. We collected 117 gastric cancer and corresponding normal tissues for immunohistochemistry analysis. In gastric cancers, 82/117 (70.1%) were positive for EZH2 and 66/117 (56.4%) for H3K27me3 proteins in contrast to only 5.41% and 7.25% of normal gastric mucosa specimens, respectively. Kaplan-Meier survival data showed the average overall and disease-free survival of EZH2 high expression patients was 25.2 and 20.2 months, respectively, shorter than that with EZH2 low expression (40.5 and 35.9 months). The average overall survival and disease-free survival of high H3K27me3 expression patients was 23.4 and 17.4 months, shorter than without H3K27me3 expression (37.6 and 34.5 months). The average overall survival and disease-free survival of patients with both EZH2 and H3K27me3 expression was 18.8 and 12.9 months, respectively, shorter than that with either alone (34.7 and 31.2 months) or with low levels of both (43.9 and 39.9 months). Multivariate Cox regression analysis showed that H3K27me3 and EZH2 expression, tumor size differentiation and clinical stage were all independent prognostic factors for predicting patient survival. This study demonstrated that detection of both EZH2 and H3K27me3 proteins can predict poor survival of gastric cancer patients, superior to single protein detection. In addition, H3K27me3 and EZH2 protein expression could predict lymph node metastasis.

Determination of Amatoxins in Lepiota brunneoincarnata and Lepiota venenata by High-Performance Liquid Chromatography Coupled with Mass Spectrometry

( Pan Long ),( Fengxia Fan ),( Bin Xu ),( Zhengmi He ),( Yuting Su ),( Ping Zhang ),( Jianwei Xie ),( Zuohong Chen ) 한국균학회 2020 Mycobiology Vol.48 No.3

Three hepatic failure poisoning incidents caused by Lepiota brunneoincarnata and Lepiota venenata mushrooms have been occurred in China in 2017, L. venenata has been described as a new species. However, the cyclopeptide toxins of these lethal mushrooms remain poorly understood. In this study, the composition and content of amatoxins in L. brunneoincarnata and L. venenata are analyzed and compared, the analysis of composition and content of amatoxins in L. venenata are reported for the first time. The results showed that b-amanitin (b-AMA), a-amanitin (a-AMA), amanin, and amaninamide were identified in L. brunneoincarnata, and a-AMA, amanin II (an analog of amanin), and an unknown compound were identified in L. venenata. The differences between L. brunneoincarnata and L. venenata in the identified compounds provide chemical evidence for L. venenata as a new species. Quantitative analysis shows that a-AMA concentrations in L. brunneoincarnata and L. venenata were 0.72-1.97mg/g dry weight, b-AMA concentrations in L. brunneoincarnata were 0.57-0.94mg/g dry weight, and b-AMA was absent in L. venenata.

Controlled fabrication and electrochemical corrosion behavior of ultrathin Ni-Cu alloy foil

Linping Yu,Long Chen,Qizhi Chen,Luli Feng,Ziyi Xu,Bo Nan,Xiyue Kang,Yuehui He 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Cost-effective ultrathin alloy foils (<20 lm) are highly expected with the development of electronicindustry and micro-system technology. In this paper, electrodeposition combined with vacuum sinteringis used to fabricate a Ni-Cu alloy foil with thickness of 12.0 (±0.2) lm. For the ultrathin Ni-Cu alloy foil, adensified structure without pores can be achieved by prolonging sintering duration at 900 ℃ for 3 h. Under the current density of 10 mA cm 2, 700 s is the optimal electrodeposition time to obtain the highesttensile strength (187 MPa) with the Ni content of 41.5 wt.% in the alloy foil. Compared with Cu foil, Ni-Cu alloy foil shows superior corrosion resistance in 3.5 wt.% NaCl solution and also HCl solutions (0.5 mol/L, 1.0 mol/L, 2.0 mol/L), respectively. The uniform composition and defect-free surface, excellent tensilestrength and corrosion resistance together exhibits the great application potential of the obtained Ni-Cualloy foil, which may provide an inspiration for future development of integrated electronic or medicaldevices.

Ce3+ triggers fenton-like processes in neutral solutions for effective catechol degradation

Xing Chen,Xu Liu,Hai-Bo Wang,Kang-Ping Cui,Rohan Weerasooriya,Shi-Long He,Guang-Hong Li,Jun Pan,Kai Zhou 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

Classical Fenton and Fenton-like processes destruct organic pollutants in water non-selectively to complete mineralization. However, the usage of classical Fenton or Fenton-like processes is often limited due to the narrow operational pH window, sludge accumulation, inefficient H₂O₂ and efficiency decline. To overcome these constraints, in this study, we used a homogeneous Fe<SUP>3+</SUP>-Ce<SUP>3+</SUP>-H₂O₂ Fenton-like process to degrade catechol at different experimental conditions. At pH 7, almost 97% of 10 mM catechol can be destructed within 60 min while the degradation by Classical Fenton or Fe<SUP>3+</SUP>-H₂O₂ Fenton-like process only 36.2% and 23.7%. The resultant solution after the degradation contains only traces of cerium ions. The sludge created by the process was extensively characterized by FTIR and XPS spectroscopy to elucidate the fate of cerium ions. Electron spin resonance (ESR) data confirmed •OH as the major free radical in Fe<SUP>3+</SUP>-Ce<SUP>3+</SUP>-H₂O₂ process. Our Fenton-like process widens the optimal pH values to neutral condition.