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.

A new strategy for stem cells therapy for erectile dysfunction: Adipose-derived stem cells transfect Neuregulin-1 gene through superparamagnetic iron oxide nanoparticles

Jianxing Cheng,Zhongjie Zheng,Wenhao Tang,Jichun Shao,Hui Jiang,Haocheng Lin 대한비뇨의학회 2022 Investigative and Clinical Urology Vol.63 No.3

Purpose: Our previous studies showed that nanotechnology improves derived adipose-derived stem cells (ADSCs) therapy for erectile dysfunction (ED). In this study, the Neuregulin-1(NRG1) gene was transfected into ADSCs with superparamagnetic iron oxide nanoparticles (SPION) further to improve the therapeutic effect of ADSCs on ED. Materials and Methods: ADSCs were isolated from epididymal adipose tissue of Sprague–Dawley rats. The optimal concentration of PEI-SPION (SPION modified with polyethyleneimine) was selected to construct the gene complex. After electrostatic binding of PEI-SPION and DNA, a PEI layer was wrapped to make the PEI-SPION-NRG1-PEI gene transfection complex. Different groups were set up for transfection tests. Lipo2000 transfection reagent was used as the control. PEI-SPION-NRG1-PEI in the experimental group was transfected under an external magnetic field. Results: When the concentration of PEI-SPION was 10 µg/mL, it had little cytotoxicity, and cell activity was not significantly affected. PEI-SPION-NRG1-PEI forms positively charged nanocomposites with a particle size of 72.6±14.9 nm when N/P ≥8. The PEI-SPION-NRG1-PEI gene complex can significantly improve the transfection efficiency of ADSCs, reaching 26.74%±4.62%, under the action of the external magnetic field. PCR and Western blot showed that the expression level of the NRG1 gene increased significantly, which proved that the transfection was effective. Conclusions: PEI-SPION can be used as a vector for NRG1 gene transfection into ADSCs. PEI-SPION-NRG1-PEI packaging has the highest transfection efficiency under the external magnetic field than the other groups. These findings may provide a new strategy for ADSCs therapy for ED.

Co-State Variable Determination in Pontryagin’s Minimum Principle for Energy Management of Hybrid Vehicles

Jianxing Zhang,Chunhua Zheng,차석원,Shanxu Duan 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.9

In order to achieve the best fuel economy for hybrid vehicles, energy management strategies should optimize the power allocation between power sources. Recently, Pontryagin’s Minimum Principle (PMP) has been attracting attention for the energy management of hybrid vehicles owing to the solution optimality and the calculation instantaneity. In the PMP, there is an important control parameter, which is defined as the co-state variable and difficult to be determined. This research mainly deals with the co-state variable, where the PMP is applied to a fuel cell hybrid vehicle (FCHV) and a hybrid electric vehicle (HEV) respectively, and the effect of the co-state variable on the optimal solution is discussed for each case. The determination of the co-state variable for the cases of certain driving cycles and uncertain driving cycles is discussed, and an online co-state variable updating method is proposed for the uncertain driving cycle cases and its effectiveness is proved.

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.

Dynamic characteristics of a planetary gear system based on contact status of the tooth surface

Ruibo Chen,Jianxing Zhou,Wenlei Sun 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

Studies on the planetary gear have attracted considerable attention because of its advantages, such as compactness, large torque-toweight ratio, vibrations, and high efficiency, which have resulted in its wide applications in industry, wind turbine, national defense, and aerospace fields. We have established a novel dynamic model of the planetary gear transmission by using Newton’s theory, in which some key factors such as time-variant meshing stiffness, phase relationships, and tooth contact characteristics are considered. The influences of gear axial tipping, operating conditions, and the meshing phase on the contact characteristics and the dynamic characteristics were researched systematically. It was found that the contact area of the tooth surface was moved due to the axial gear tipping, which obviously affected the meshing stiffness. With the increase in the inclination angle of the sun gear, the meshing stiffness decreases, which produces an evident influence on the high natural frequency in the planetary transmission system. In terms of the dynamic characteristics of the system, the component of rotating frequency appeared in the dynamic meshing force of the sun gear and the planetary gear. Moreover, the floating track of the center wheel varied significantly and exhibited an oval distribution as the inclination angle of the sun gear changed. When the inclination angle of the sun gear increased, the rotating frequency component increased significantly, but the other meshing frequency components remained unchanged; meanwhile, the deformation of the floating track also increased. If the inclination angle of the sun gear changes, the vibration state of the system and the collision impact could become more serious, and the lifetime of the planetary transmission system will reduce. Furthermore, when the load was increased, we found that the gear-tooth contact zone transformed from line contact to surface contact, the meshing stiffness increased, the effect of high natural frequency on the planetary transmission system became more evident, but its low-order natural frequency remained stable. With regard to the dynamic characteristics of the system, the components of the major frequency at the external gearing remained unchanged, but the rotation frequency of the sun gear and the meshing frequency amplitude increased linearly with the increase in load. In conclusion, the variation in the meshing stiffness of the planetary gear system had minor impact on the low-order natural frequency, but had a significant impact on the high natural frequency of the planetary transmission system due to the phase variation of the gear.

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 transmission error and torsional stiffness of RV reducer under wear

Ronghua Zhang,Jianxing Zhou,Zheng Wei 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

In order to discuss the influence of wear dynamic evolution on the degradation of core transmission performance, transmission error and meshing torsional stiffness of RV reducer, taking BX-40E reducer as the research object, based on Langkali-Nikraves contact force model and Archard wear theory, the wear coefficients with different position conditions were obtained through equivalent wear experiments. The RV transmission dynamic model considering wear, meshing stiffness, meshing force, meshing tooth pairs and transmission error linkage was established by using centralized parameter method and dynamic subsystem method. Compared with the traditional tooth profile wear simulation, which distribution and size of the wear depth curves were more and more different with wear dynamic evolution, theoretically concluded that the dynamic update of wear coefficient is necessary and correct for the accurate simulation of tooth surface wear. The transmission error shows a "double hump" distribution mapped to the wear depth of the tooth profile, and deteriorates with the wear accumulation. The equivalent torsional stiffness of cycloid pin teeth decreases piecewise approximately linearly due to wear. In the previous stage, the reduction rate is small because the tooth detachment first occurs at the tooth top and root, and the single tooth torsional stiffness near the tooth top and root is smaller. The research results provide a new idea and theoretical basis for improving the transmission accuracy, stability holding ability, wear reduction and life extension of RV reducer.

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.

Study on the coupling relationship between wear and dynamics under steady uniform temperature field of planetary gear system

Ning Dong,Jianxing Zhou,Ruiting Tong,Quanwei Cui,Yiyi Kong,Junshang Feng,Shichen Xiao 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

Wear of tooth profiles and thermal deformation caused by temperature changes are difficult to avoid in gear systems and have important effects on the performance, even to failure. In this paper, a dynamic wear prediction model with coupled thermal deformation and wear is proposed to study the interaction between wear and dynamics of planetary gear system under temperature field, accounting for the effect of temperature on material properties. The system's performance under different wear cycles and temperatures is analyzed. The results show that the difference in the structure makes the curve shape of the thermal deformation error for the external and internal gear pairs completely different, which in turn affects the dynamic response. The distribution and the degree of fluctuation of tooth profile wear depth change as the mesh cycle increases. The early wear is beneficial to the system's uniform load performance and vibration, and the performance decreases as the wear increases, but the external and internal gear pairs are affected by wear to a different extent. The thermal deformation and wear errors have competing or facilitating mechanisms depending on the temperature difference and the degree of wear.

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.