Fabrication of carbon nanotube-loaded TiO2@AgI and its excellent performance in visible-light photocatalysis

Liu Yang,Yang An,Bin Dai,Xuhong Guo,Zhiyong Liu,Banghua Peng 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

Novel, visible light driven CNTs-TiO2@AgI hybrid materials were synthesized by a simple solvothermaldissolution- precipitation method, during which the acid vapor treated carbon nanotubes (CNTs) as template, AgI as sensitizer and TiO2 as the bridge unified them to form a ternary composite. The morphology and chemical components of as-prepared samples were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and XPS characterizations indicated that anatase TiO2 and crystal AgI co-existed in the composite. HRTEM demonstrated CNTs were decorated with well-dispersed AgI and TiO2 nanoparticles (NPs), and TiO2 had an intimate connection with both AgI and CNTs. Diffusive reflectance UV-vis spectroscopy of CNTs-TiO2@AgI nanocomposite was extended to the whole UV-visible region due to adding of CNTs and AgI NPs. Degradation of Rhodamine B (RhB) polluted water using CNTs-TiO2@AgI NPs was carried out under visible light irradiation, and it showed higher degradation efficiency than CNTs-TiO2, TiO2@AgI, and CNTs@AgI NPs. The primary reason for the enhanced photocatalytic property was attributed to the synergic effect in CNTs-TiO2@AgI, which included the good adsorption ability and electrical conductivity of CNTs as well as the intimate connection and hetero-junctions among AgI, TiO2, and CNTs. Meanwhile, the as-prepared hybrid materials can be easily separated and reclaimed from the liquid phase, and the recycling tests indicated CNTs-TiO2@AgI had renewable performance.

Fire Damage Identification in RC Beams based on Support Vector Machines considering Vibration Test

Chaofeng Liu,Caiwei Liu,Chengxin Liu,Xuhong Huang,Jijun Miao,Wenlong Xu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.10

In order to obtain the degree of damage in reinforced concrete (RC) beams exposed to fire, using the equivalent fire exposure time as the damage index, a new method of damage identification based on the support vector machine technology was proposed. Firstly, the feasibility analysis was conducted based on finite element models of simply supported beams. Thereafter, four RC simply supported beams were designed for fire test and vibration test, which were used to amend the finite element model and the SVM-based identification method. Fire tests were carried out on 4 beams for 60, 90, 120, and 150 min, respectively. During and after the fire tests, structural modal information were recorded. The first two order modal information, as SVM input paraments, was used to predict the equivalent fire exposure time based on SVM. The predicted results were very close to the actual fire exposure time. The residual bearing capacities of the beams after fire were calculated according to the predicted fire exposure time, which were close to experimental results. It indicated that the equivalent fire exposure time as the output parameter for damage identification was reliable. Finally, on the basis of damage identification method for simply supported beams, a new three-step positioning method was established for identifing the degree of damage in continuous beams. The method was applied to a thress-span continuous beam. The numercial situlation results revealed that the three-step positioning method was accurate.

A New Dual-Active Soft-Switching Converter for an MTEM Electromagnetic Transmitter

Xuhong Wang,Yiming Zhang,Wei Liu 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

In this study, a new dual-active soft-switching converter is proposed to improve conversion efficiency and extend the load range for an MTEM electromagnetic transmitter in geological exploration. Unlike a conventional DC/DC converter, the proposed converter can operate in passive soft-switching, single-active soft-switching, or dual-active soft-switching modes depending on the change in load power. The main switches and lagging auxiliary switches of the converter can attain soft-switching over the entire load range. The conduction and switching losses are greatly reduced compared with those of ordinary converters under the action of the cut-off diodes and auxiliary windings coupled to the main transformer in the auxiliary circuits. The conversion efficiency of the proposed converter is significantly improved, especially under light-load conditions. First, the working principle of the proposed converter is analyzed in detail. Second, the relationship between the different operating modes and the load power is given and the design principle of the auxiliary circuit is presented. Finally, the Saber simulation and experimental results verify the feasibility and validity of the converter and a 50 kW prototype is implemented.

A New Dual-Active Soft-Switching Converter for an MTEM Electromagnetic Transmitter

Wang, Xuhong,Zhang, Yiming,Liu, Wei The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

In this study, a new dual-active soft-switching converter is proposed to improve conversion efficiency and extend the load range for an MTEM electromagnetic transmitter in geological exploration. Unlike a conventional DC/DC converter, the proposed converter can operate in passive soft-switching, single-active soft-switching, or dual-active soft-switching modes depending on the change in load power. The main switches and lagging auxiliary switches of the converter can attain soft-switching over the entire load range. The conduction and switching losses are greatly reduced compared with those of ordinary converters under the action of the cut-off diodes and auxiliary windings coupled to the main transformer in the auxiliary circuits. The conversion efficiency of the proposed converter is significantly improved, especially under light-load conditions. First, the working principle of the proposed converter is analyzed in detail. Second, the relationship between the different operating modes and the load power is given and the design principle of the auxiliary circuit is presented. Finally, the Saber simulation and experimental results verify the feasibility and validity of the converter and a 50 kW prototype is implemented.

Application of Steel-tubed Concrete Structures in High-rise Buildings

Zhou, Xuhong,Liu, Jiepeng Council on Tall Building and Urban Habitat Korea 2019 International journal of high-rise buildings Vol.8 No.3

Making full use of material strength, maintaining sufficient ductility of structural components, and ensuring simple and robust connections are crucial to the development of steel-concrete composite structures. The steel-tubed concrete structure uses thin-walled steel tube to provide confinement, so that the strength and ductility of the concrete core are improved. Meanwhile, the thin-walled steel tube is terminated at the beam-column joint to avoid the local buckling problem and simplify the connections between steel tube and RC members. A brief overview of the development of steel-tubed concrete structures is presented. Through the discussion on the structural behavior of steel-tubed concrete and the introduction of typical practical projects, the prospects for future research are highlighted.

Shear behavior of short square tubed steel reinforced concrete columns with high-strength concrete

Xiang Li,Xuhong Zhou,Jiepeng Liu,Xuanding Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.3

Six shear-critical square tubed steel reinforced concrete (TSRC) columns using the high-strength concrete (fcu,150 = 86.6MPa) were tested under constant axial and lateral cyclic loads. The height-to-depth ratio of the short column specimens was specified as 2.6, and the axial load ratio and the number of shear studs on the steel shape were considered as two main parameters. The shear failure mode of short square TSRC columns was observed from the test. The steel tube with diagonal stiffener plates provided effective confinement to the concrete core, while welding shear studs on the steel section appeared not significantly enhancing the seismic behavior of short square TRSC columns. Specimens with higher axial load ratio showed higher lateral stiffness and shear strength but worse ductility. A modified ACI design method is proposed to calculate the nominal shear strength, which agrees well with the test database containing ten short square TSRC columns with shear failure mode from this study and other related literature.

Vibration performance characteristics of a long-span and light-weight concrete floor under human-induced loads

Cao, Liang,Liu, Jiepeng,Zhou, Xuhong,Chen, Y. Frank Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.3

An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.

Axial load behavior and stability strength of circular tubed steel reinforced concrete (SRC) columns

Biao Yan,Jiepeng Liu,Xuhong Zhou 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.5

The tubed steel reinforced concrete (SRC) column is a composite column in which the outer steel tube is mainly used to provide confinement on the core concrete. This paper presents experimental and analytical studies on the behavior of circular tubed SRC (TSRC) columns subjected to axial compression. Eight circular TSRC columns were tested to investigate the effects of length-to-diameter ratio (L/D) of the specimens, diameter-to-thickness ratio (D/t) of the steel tubes, and use of stud shear connectors on the steel sections. Elastic-plastic analysis on the steel tubes was used to investigate the mechanism of confinement on the core concrete. The test results indicated that the tube confinement increased the strength and deformation capacity for both short and slender columns, and the effects on strength were more pronounced for short columns. A nonlinear finite element (FE) model was developed using ABAQUS, in which the nonlinear material behavior and initial geometric imperfection were included. Good agreement was achieved between the predicted results using the FE model and the test results. The test and FE results were compared with the predicted strengths calculated by Eurocode 4 and the AISC Standard. Based on the analytical results, a new design method for this composite column was proposed.

Analysis of Peripheral B Cell Subsets in Patients With Allergic Rhinitis

Jing Luo,Huanhuan Guo,Zhuofu Liu,Tao Peng,Xianting Hu,Miaomiao Han,Xiangping Yang,Xuhong Zhou,Huabin Li 대한천식알레르기학회 2018 Allergy, Asthma & Immunology Research Vol.10 No.3

Purpose: Recent evidence suggests that B cells can both promote and inhibit the development and progression of allergic disease. However, the characteristics of B cell subsets in patients with allergic rhinitis (AR) have not been well documented. This study aimed to analyze the characteristics of B cell subsets in the peripheral blood of AR patients. Methods: Forty-seven AR patients and 54 healthy controls were enrolled in this study, and the B cell subsets in peripheral blood of all subjects were analyzed by flow cytometry. Moreover, the serum total immunoglobulin E (IgE) and IgE concentrations secreted into the cultured peripheral blood mononuclear cells (PBMCs) were measured by using enzyme-linked immunosorbent assay. Results: We found the peripheral blood of AR patients contained higher percentages of memory B cells, plasma cells, and CD19+CD24hiCD27+ regulatory B cells (Bregs) than those of age-matched healthy controls (P<0.05), while the percentages of naïve B cells and CD19+CD24hiCD38hi Bregs were significantly lower in AR patients than in healthy individuals (P<0.05). In addition, the serum total IgE and IgE concentrations secreted into the cultured PBMCs were elevated in AR patients than in the healthy controls (P<0.05). Conclusions: Our findings indicate that AR patients were characterized by increase in terminally differentiated memory B cells or plasma cells and decreases in CD19+CD24hiCD38hi Breg cells in the peripheral blood.

Experimental Research on Impact Resistance of Partially Precast Concrete Beams

Huimin Mao,Xueyuan Yan,Chenchen Zong,Cihang Lin,Xuhong Liu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.9

A building may be subjected to multiple accidental loads during its service-life. Partially precast concrete (PC) beam is a primary force-bearing member. When subjected to an impact load, its impact resistance will significantly affect the overall safety of the structure. In this study, five PC beams were designed and manufactured, and drop-hammer impact tests were performed. The influences of impact mass and impact height on the failure mode and the dynamic response of the component under different loading conditions were examined. The typical failure mode of the test beam under a dynamic load was derived from the failure mode and crack distribution. The dynamic responses such as impact force, supporting reaction force, and displacement–time-history curve were obtained by the test. With increasing impact energy, the peak impact force increased from 3,353 to 3,708 kN, the peak mid-span displacement increased from 33.6 to 47.3 mm, and the residual mid-span displacement increased from 11.9 to 15.1 mm. Subsequently, the law of energy dissipation in the impact process was analyzed using the combined curves of the impact force-mid-span displacement and support reaction force-mid-span displacement. Furthermore, the result obtained by the integration of the reaction force-displacement curve in the middle of the span is more suitable for evaluating the overall energy consumption of the beam. The vibration energy and internal energy of the beam itself account for the primary part of the remaining energy.