Progressive Failure of Precast Shear Wall Structure for RC Composite Column Confined Uniform Hollow Panels under Cyclic Loading

Jianxing Sun,Mengyao Ci,Guangda Xu,Rucheng Wang,Weibin Ni,Zongmei Xu,Shao-Jie Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

To increase the assembly construction efficiency of low-rise and multi-story buildings in rural areas, the precast shear wall for RC composite column confined uniform hollow panels was designed in this paper. The seismic performance and failure mechanism of the structure are studied by combining low cyclic load test with finite element and theoretical analysis. The study found that the connection between the components is safe. The structure has three progressive failure processes that are the interaction stage, composite column constrained dense column work stage and weak framework stage. The structure has good bearing and capacity of energy dissipation, and the ductility coefficient of the specimen is 2.89. In addition, the finite element model is established based on ABAQUS, and the damage evolution process of the structure is visually represented by the damage nephogram. In combination with test and simulation, calculation methods of shear capacity of the shear wall are established. The ratio of test value to calculated value in the interaction stage and weak framework stage is 1.14 and 1.06 respectively. The calculation method is reliable and has clear physical significance. The study can provide a reference for the application in low-rise and multi-story buildings.

Low noise optimization of two-stage gearbox housing structure based on acoustic contribution analysis and topology optimization

Le Qi,Jianxing Zhou,Pengcheng Jin,Mingming Wang,Yongzheng Su,Hengyu Zhou,Guochun Liu,Lirui Song 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

In this paper, a rib layout optimization method that can efficiently reduce the radiated noise of gearboxes is proposed. Taking the secondary gearbox as the research object, the radiated noise of the housing is calculated using the FEM/BEM method, the process of determining the region with the maximum acoustic contribution is illustrated, and a topology optimization model that can reduce the air noise on the field points of the gearbox is established with the surface normal velocity of the region as the optimization target. The method is applied to add new noise reduction ribs on the surface of the gearbox. The results show that after combining the topology optimization with the acoustic contribution analysis, the sound pressure in the area with the highest sound pressure on the gearbox sound field is significantly reduced by adding new noise reduction ribs according to the optimization results.

The New Structural Design Process of Supertall Buildings in China

Lianjin, Bao,Jianxing, Chen,Peng, Qian,Yongqinag, Huang,Jun, Tong,Dasui, Wang Council on Tall Building and Urban Habitat Korea 2015 International journal of high-rise buildings Vol.4 No.3

By the end of 2014, the number of completed and under-construction supertall buildings above 250 meters in China reached 90 and 129, respectively. China has become one of the centers of supertall buildings in the world. Supertall buildings in China are getting taller, more slender, and more complex. The structural design of these buildings focuses on the efficiency of lateral resisting systems and the application of energy dissipation. Furthermore, the research, design, and construction of high-performance materials, pile foundations, and mega-members have made a lot of progress. Meanwhile, more and more challenges are presented, such as the improvement of structural system efficiency, the further understanding of failure models, the definition of design criteria, the application of high-performance materials, and construction monitoring. Thus, local structural engineers are playing a more important role in the design of supertall buildings.

Research on dynamic characteristics and radiation noise of a helicopter main reducer based on finite element and boundary element method

Jingqi Zhang,Jianxing Zhou,Shengnan Wang,Haiwei Wang,Feng-xia Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

In order to solve the problem of radiation noise of helicopter reducer with symmetrical structure, a simulation method is proposed to predict the noise of gearbox of a helicopter reducer from steady dynamic response to the acoustic radiation calculation. Primarily, taking the influence of time-varying stiffness into consideration, the lumped mass model of gear-rotorbearing system is established. The dynamic load of transmission system is solved by NewMark-β method, which is regarded as excitation of the gearbox. Then finite element model of housing is established, the radiated noise of the housing is predict by finite element and boundary element method, the influence of multi-source excitation on the radiated noise of the gearbox is analyzed. Finally, the radiated noise of the reducer under different working conditions is explored. All conclusions of this research could provide theoretical reference for vibration and noise reduction of helicopter reducer.

Biodegradation of omethoate by Bacillus sp. YB-10: optimization of culture conditions and degradation characteristics

Riqiang Li,Jianxing Wang,Songhui Li 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.4

Omethoate is an acute organophosphorus pesticide which is widely used. It presents a high pollution potential and health risk nowadays. In this study, Bacillus sp. YB-10, which was isolated from the activated sludge of a pharmaceutical wastewater treatment plant, was used for degrading omethoate. The culture conditions and degradation characteristics were investigated. Results showed that the Bacillus sp. YB-10 could degrade omethoate through co-metabolism. The optimal carbon and nitrogen sources were glucose and NH₄NO₃, respectively. Response surface methodology (RSM) results showed that the most appropriate nutrition ratio of C:N:P was 3:1:1 when degrading 1,000 ㎎/L of omethoate. Omethoate degradation kinetics could be described by a first-order rate equation. The optimal degradation conditions were pH of 7.0, temperature of 30℃, initial bacteria concentration of 0.25%, rotation speed of 150 r/min. Under the optimal conditions, the degradation rate reached 77.24% within 5 d by the Bacillus sp. YB-10 when the initial omethoate concentration was 1,000 ㎎/L.

Study on wear evolution of spur gears considering dynamic meshing stiffness

Ning Dong,Quanwei Cui,Jianxing Zhou,Ruiting Tong,Haiwei Wang,Feng-xia Lu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.7

Wear is an inevitable phenomenon in gear systems and has a great impact on performance and longevity. In view of the fact that the actual variation of meshing stiffness in the double teeth contact region and the nonlinear relationship between meshing stiffness and force are ignored in previous wear prediction studies, a new method with loss-of-lubrication is proposed in this study. A translational-torsional dynamic model is developed for the coupling effect between wear and dynamic characteristics of external spur gears. To obtain more precise dynamic responses, the meshing stiffness and force are coupled with tooth wear, taking into account the structural coupling effect and nonlinear contact. The tooth surface is then discretized, and a wear model is developed based on Archard wear equation, in which the average pressure is used for the engaging point. Experiments and numerical simulations are carried out to analyze the wear pattern and the interaction between wear and dynamic responses. The results show that the progressive wear process is self-adaptive. Meanwhile, the area with the largest wear depth moves slightly from the dedendum and addendum to the pitch line as the wear cycle increases. When the wear depth is at the level of the tooth profile deviation, the influence of wear on meshing stiffness is very small within the single tooth contact region. However, there is a significant decrease in the stiffness of the double teeth contact, and this decrease is related to the wear cycle and torque. At the initial wear phase, as the load increases, the fluctuation of the wear depth within the engaging-in region intensifies and the overall wear depth increases. With the increment of rotate speed, the engaging-in impact makes the fluctuant area of wear depth become larger.

TRIM24-Mediated Acetylation of STAT6 Suppresses Th2-Induced Allergic Rhinitis

Yue Liyan,Jia Qiaojing,Dong Jinhui,Wang Jianxing,Ren Xiumin,Xu Ou 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.5

Purpose: Allergic rhinitis (AR) is a T helper type 2 (Th2)-mediated inflammatory disease. The E3 ligase tripartite motif-containing 24 (TRIM24) regulates the recruitment of acetyltransferase CREB-binding protein (CBP) to signal transducer and activator of transcription 6 (STAT6). CBP mediates the acetylation of STAT6 and decreases its activity. To date, the precise role of TRIM24 in AR has not been fully interpreted. Herein, our study aimed to explore the functions of TRIM24 in AR. Methods: The expression of TRIM24 in peripheral blood mononuclear cells (PBMCs) and CD4+ T cells from patients with AR was measured. TRIM24-conditional knockout mice with TRIM24 deficiency in CD4+ T cells were generated. Wide-type (WT) AR mice and TRIM24-conditional knockout AR mice were established. Then, AR symptoms and interleukin (IL)-4 levels were compared. Further, the proliferation, activation and polarization of CD4+ T cells from WT mice and TRIM24 knockout mice after stimulation were determined. The effects of TRIM24 deficiency on STAT6 activities were also evaluated. Results: Downregulated TRIM24 expression was detected in PBMCs and CD4+ T cells from patients with AR. TRIM24 conditional knockout mice had more sever AR symptoms with elevated IL-4 production. TRIM24-knockout CD4+ T cells had similar proliferation and activation when compared to WT CD4+ T cells, while they had enhanced Th2 polarization. TRIM24-knockout CD4+ T cells had decreased acetylation of STAT6 and enhanced STAT6 activities after IL-4 stimulation. The regulation of STAT6 activities by TRIM24 depended on TRIM24 N terminal RIGN domain and Lys383 acetylation site of STAT6. Conclusions: TRIM24 suppresses Th2-mediated AR by regulating the acetylation of STAT6.

Constructing all-in-one graphene-based supercapacitors for electrochemical energy storage via interface integration strategy

Zhu Yucan,Peng Long,Chen Song,Feng Yuchao,Xia Jianxing,Wang Wei,Chen Liang,Yin Hong,Zhou Minjie,Hou Zhaohui 한국탄소학회 2023 Carbon Letters Vol.33 No.3

With the rapid development of flexible wearable electronic products, flexible all graphene-based supercapacitors (FGSCs) with reduced graphene oxide rGO//graphene oxide (GO)//rGO structure have attracted substantial attention due to their unique structures and energy storage mechanism. However, restricted by design idea and preparation technology, improvement of capacitance performance for the FGSCs is not obvious recently. Herein, we demonstrate that an interface integration strategy of constructing the high-performance FGSCs with compact structure. Hydroquinone (HQ)-modified rGO (HQ-rGO) films (electrode materials) and sulfuric acid-intercalated GO films (electrolyte/separator) are assembled into the FGSCs utilizing hydrogen bonding and capillary contractility. The HQ further improves the electrochemical capacitance of electrode materials. The synergistic effect of the hydrogen bonding and capillary contractility guarantees compact and stable structure of the device. The resulting FGSCs exhibit an excellent areal capacitance of 804.6 mF cm−2 (@2 mA cm−2) and 441 mF cm−2 (@30 mA cm−2), and their highest energy and power densities can achieve 109.5 μWh cm−2 and 21,060 μW cm−2, respectively. These performances are superior to other all-in-one graphene-based SCs reported. Therefore, the construction technology of the FGSCs is a promising for developing all graphene-based SCs with high-performance.