Study of Robustness Approximate Time-Optimal System

Xu, Song Yuan,Yao, Li Qiang,Rong, Hong Bing,Xu, Shao Qing 대한전자공학회 1992 HICEC:Harbin International Conference on Electroni Vol.1 No.1

Using the $quot;bang-bang$quot;control the system can obtain the optimal time. But there have the chatter and the bad robustness after considering the practical factors. If we use the chang structure principle, the chatter will be diminated and the system will get the strong robustness. This paper adopted this two kinds of the principles to design the satellite attitute control system and the satisfied results were received.

Dynamic Analysis of AP1000 Shield Building Considering Fluid and Structure Interaction Effects

Qiang Xu,Jianyun Chen,CHAOBI ZHANG,Jing Li,Chunfeng Zhao 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.1

The shield building of AP1000 was designed to protect the steel containment vessel of thenuclear reactor. Therefore, the safety and integrity must be ensured during the plant life inany conditions such as an earthquake. The aim of this paper is to study the effect of waterin the water tank on the response of the AP1000 shield building when subjected to threedimensionalseismic ground acceleration. The smoothed particle hydrodynamics method(SPH) and finite element method (FEM) coupling method is used to numerically simulatethe fluid and structure interaction (FSI) between water in the water tank and the AP1000shield building. Then the grid convergence of FEM and SPH for the AP1000 shield building isanalyzed. Next the modal analysis of the AP1000 shield building with various water levels(WLs) in the water tank is taken. Meanwhile, the pressure due to sloshing and oscillation ofthe water in the gravity drain water tank is studied. The influences of the height of water inthe water tank on the time history of acceleration of the AP1000 shield building are discussed,as well as the distributions of amplification, acceleration, displacement, andstresses of the AP1000 shield building. Research on the relationship between the WLs in thewater tank and the response spectrums of the structure are also taken. The results showthat the high WL in the water tank can limit the vibration of the AP1000 shield building andcan more efficiently dissipate the kinetic energy of the AP1000 shield building by fluidstructureinteraction.

Cyclic Behavior of Steel Frame Joints in the Offshore Atmospheric Environment

Qiang Xu,Xiaoyu Shang,Shansuo Zheng 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.3

The natural deterioration of mild steel elements exposed to off shore atmospheric environments compromises the long-term safety of existing steel buildings. An experimental study was conducted to investigate the eff ect of the off shore atmospheric environment on the seismic performance of steel frame joints. An indoor accelerated corrosion test was conducted to simulate the degradation of the mechanical properties of the materials and steel frame joints in the off shore atmospheric environment. After determining the corrosion rate by weighing after rust removal, the yield strength, ultimate strength, modulus of elasticity, and elongation of three test specimen with diff erent thicknesses were obtained by regression of the tensile failure test, which demonstrated a linear decay relationship with the corrosion rate. Under four diff erent corrosion degrees and three diff erent low-cycle reciprocating loads, the failure modes of 12 steel frame joints were all plate-tearing at welded through holes. However, the diff erence is that the joints had ductile failure under equal-amplitude 90 mm loading and brittle failure under variable-amplitude loading. The eff ects of corrosion on the hysteresis behavior, deformation degradation, strength degradation, and energy dissipation capacity of steel frame joints were analyzed. The test results indicate that corrosion has signifi cant eff ects on the seismic performance of steel frame joints. With the increase in corrosion degree, the energy dissipation capacity of steel frame joints declines more signifi cantly than other performance indicators, and the yield platform of the steel frame joints is not evident.

Analysis and Experimental Verification of Digital Self-Interference Cancelation for Co-time Co-frequency Full-Duplex LTE

Qiang Xu,Xin Quan,Zhiliang Zhang,Youxi Tang,Ying Shen 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.1

Dynamic Analysis of AP1000 Shield Building Considering Fluid and Structure Interaction Effects

Xu, Qiang,Chen, Jianyun,Zhang, Chaobi,Li, Jing,Zhao, Chunfeng Korean Nuclear Society 2016 Nuclear Engineering and Technology Vol.48 No.1

The shield building of AP1000 was designed to protect the steel containment vessel of the nuclear reactor. Therefore, the safety and integrity must be ensured during the plant life in any conditions such as an earthquake. The aim of this paper is to study the effect of water in the water tank on the response of the AP1000 shield building when subjected to three-dimensional seismic ground acceleration. The smoothed particle hydrodynamics method (SPH) and finite element method (FEM) coupling method is used to numerically simulate the fluid and structure interaction (FSI) between water in the water tank and the AP1000 shield building. Then the grid convergence of FEM and SPH for the AP1000 shield building is analyzed. Next the modal analysis of the AP1000 shield building with various water levels (WLs) in the water tank is taken. Meanwhile, the pressure due to sloshing and oscillation of the water in the gravity drain water tank is studied. The influences of the height of water in the water tank on the time history of acceleration of the AP1000 shield building are discussed, as well as the distributions of amplification, acceleration, displacement, and stresses of the AP1000 shield building. Research on the relationship between the WLs in the water tank and the response spectrums of the structure are also taken. The results show that the high WL in the water tank can limit the vibration of the AP1000 shield building and can more efficiently dissipate the kinetic energy of the AP1000 shield building by fluid-structure interaction.

Distinctions Between Clinicopathological Factors and Prognosis of Alpha-fetoprotein Negative and Positive Hepatocelluar Carcinoma Patients

Xu, Jia,Liu, Chang,Zhou, Lei,Tian, Feng,Tai, Ming-Hui,Wei, Ji-Chao,Qu, Kai,Meng, Fan-Di,Zhang, Ling-Qiang,Wang, Zhi-Xin,Zhang, Jing-Yao,Chang, Hu-Lin,Liu, Si-Nan,Xu, Xin-Shen,Song, Yan-Zhou,Liu, Jun,Z Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.2

Serum alpha-fetoprotein (AFP) is a significant marker for clinical diagnosis and prognosis evaluation in hepatocellular carcinoma (HCC) patients. However, some proportion of liver cancer patients are AFP-negative (AFP ${\leq}$20ng/ml). In order to study the differences between clinicopathological factors and prognosis of alpha-fetoprotein negative and positive patients, a total of 114 cases (41 AFP-negative and 73 AFP-positive) were selected for our research. By systematically statistical analysis, the results demonstrated that compared with AFP-negative patients, AFP-positive examples were more likely to feature cirrhosis nodules, non-complete neoplasm capsules, and a poor Edmondson-steiner grade. Furthermore, AFP-negative patients demonstrated a favorable long-term prognosis. By univariate analysis and multivariate analysis with Cox's proportional hazards model, multiple tumors were found to be independent risk factors for worse survival of AFP negative patients; however, less tumor-free margins, multiple tumors and Edmondson-steiner grades III/IV, proved to be independent risk factors leading to a poor prognosis of AFP positive cases. Finally, we can infer that high levels of AFP signify a highly malignant tumor and unfavorable prognosis.

Flexural Behavior and Prediction Model of Basalt Fiber/Polypropylene Fiber-Reinforced Concrete

Qiang Fu,Zhaorui Zhang,Wenrui Xu,Xu Zhao,Lu Zhang,Yan Wang,Ditao Niu 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.5

The flexural behavior of basalt fiber (BF)/polypropylene fiber (PF)-reinforced concrete (BPRC) was investigated. When the content of BF and PF is 0.1%, the addition of fibers increases the compressive strength of concrete. A BF content of 0.1% has the most obvious effect on improving the compressive strength, but a hybrid fiber content of 0.2% exhibits a negative effect on the compressive strength. The addition of BF and PF can increase the flexural strength and the expansion tortuosity of the fracture cracks, thus enhancing the ductility of concrete. The hybrid fibers with content of 0.1% are most beneficial to increase the flexural strength. However, the ductility of concrete and the tortuosity of fracture crack decrease with the matrix strength, and the improvement proportion of fibers on the flexural strength also decreases. When the BF and PF are mixed, compared to the case of single fiber added, there is no significant change in the damage of BF, whereas the damage of PF is more severe. The flexural toughness index FTδ effectively characterizes the change in the flexural toughness of BPRC. The hybrid fiber contents of 0.1% and 0.2% exhibit the most significant improving effect on FT-l/600 and FT-l/150, respectively. Considering the influence of fibers on the compressive strength, flexural strength and flexural toughness of concrete, a hybrid content of 0.1% is the optimal choice of fiber content. A prediction model for flexural strength of BPRC is proposed based on the composite material theory.

An ABC-BP-ANN Algorithm for Semi-active Control for Magnetorheological Damper

Qiang Xu,Jianyun Chen,Xiaopeng Liu,Jing Li,Chenyang Yuan 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.6

The Magnetorheological (MR) damper is one of the most popular semi-active devices, which uses MR fluids to produce controllable dampers. In this work, the Back-propagation (BP) Artificial Neural Network (ANN) optimized by the Artificial Bee Colony (ABC) algorithm (ABC-BP-ANN) is proposed to obtain the required voltage for semi-active control of MR damper simulated by Spencer model. It is found that the control-forces of MR damper are close to the results of active control algorithms such as the conventional Linear Quadratic Regulator (LQR) control algorithm. The initial weights and the thresholds of BP-ANN are regarded as solutions; the training errors of BP-ANN are used for the cost function and ABC algorithm is used to optimize the initial weights and the thresholds of BP-ANN. The proposed model uses the Spencer model to calculate the train samples to train proposed ABC-BP-ANN model. The proposed ABC-BP-ANN model predicts the voltage based on the results of control-force calculated by LQR model. Several numerical examples are used to verify the proposed model. The results show that the control-forces of MR damper calculated by proposed model are close to those calculated by LQR algorithm. The proposed ABC-BP-ANN inversion algorithm for obtaining the voltage for MR damper has greater computational efficiency and higher accuracy than the conventional BP-ANN algorithm.

Theoretical Prediction Model for Surface Settlement Caused by the Excavation of New Tunnels Undercrossing Existing Tunnels Based on Modified Stochastic Medium Theory

Qiang Xu,Shengxiang Lei,Yongquan Zhu,Wei Zhao,Cong Wang,Dapeng Wang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

The deformation pattern of the stratum caused by constructing a new metro tunnel crossing an existing tunnel is different from the deformation pattern caused by general tunnel construction. However, the prediction results by the ordinary surface settlement prediction model often bring significant errors because the complex influence of existing tunnels on the surface settlement caused by the excavation of new tunnels is always neglected. Based on the equivalent layered method and stochastic medium theory, a prediction model for the surface settlement due to excavating a new tunnel under an existing tunnel in the heterogeneous stratum was established. By equating the bending stiffness of an existing tunnel before and after applying the equivalent layered method, the layer index was determined. The critical parameters of the stochastic medium theory were derived based on the relationship between the critical parameters of both the Peck empirical formula and the stochastic medium theory. The surface settlement of some typical projects was predicted and compared by the prediction model in this paper and the ordinary prediction model. The comparison shows that the proposed prediction model and parameter determination method in this paper had high accuracy and applicability. The results of the prediction model in this paper fit the results of numerical calculation. The research of this paper can provide a new method for the theoretical prediction of surface settlement caused by the excavation of a new tunnel under an existing tunnel in the heterogeneous stratum and the determination of critical parameters of the stochastic medium theory.problem in the construction industry, and helps reducing the material waste and budget cost.

A Dynamic Modeling Approach to Simulate Groundwater Discharges into a Tunnel from Typical Heterogenous Geological Media During Continuing Excavation

Qiang Xia,Mo Xu,Han Zhang,Qiang Zhang,Xian-xuan Xiao 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.1

Most of the analytical and numerical models of tunnel groundwater inflow ignore the excavation process, leading to inaccurate prediction of discharge rate. A dynamic modeling approach was introduced by redevelopment of MODFLOW to simulate the change of groundwater flow step by step in accord with tunnel excavation. The drilling tunnel was conceptualized as a changing boundary condition, which was modeled by dividing the drilling process into a series of successive steps. The impact of permeability heterogeneity on groundwater flow was studied through a comparison between a homogeneous hydraulic conductivity case and a synthetic heterogeneous one. It was found that the discharge rate at drilling front kept stable in the homogeneous case, resulting in a linear increase in the total discharge rate, similar to the analytical solution by Perrochet (2005). In contrast, the front and total discharge rate were influenced significantly by the variability of permeability in the heterogeneous case. The time-dependent discharge rate at a given place was subject to an exponential decay for both cases with the maximum inflow occuring at the beginning of excavation. The relationship between discharge rate and hydraulic properties was further investigated in a high-K zone. It revealed that maximum discharge rate was proportional to hydraulic conductivity (K) and specific storage (Ss). The decaying rate of discharge was time-dependent and also proportional to the value of K and Ss. The water budget analysis demonstrated that water released from storage of the high-K zone was the major source of tunnel discharge at early times.