Random vibration analysis of train-slab track-bridge coupling system under earthquakes

Zhi-ping Zeng,Xian-feng He,Yan-gang Zhao,Zhi-wu Yu,Ling-kun Chen,Wen-tao Xu,Ping Lou 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.5

This study aimed to investigate the random vibration characteristic of train-slab track-bridge interaction system subjected to both track irregularities and earthquakes by use of pseudo-excitation method (PEM). Each vehicle subsystem was modeled by multibody dynamics. A three-dimensional rail-slabgirder-pier finite element model was created to simulate slab track and bridge subsystem. The equations of motion for the entire system were established based on the constraint condition of no jump between wheel and rail. The random load vectors of equations of motion were formulated by transforming track irregularities and seismic accelerations into a series of deterministic pseudo-excitations according to their respective power spectral density (PSD) functions by means of PEM. The time-dependent PSDs of random vibration responses of the system were obtained by step-by-step integration method, and the corresponding extreme values were estimated based on the first-passage failure criterion. As a case study, an ICE3 high-speed train passing a fifteen-span simply supported girder bridge simultaneously excited by track irregularities and earthquakes is presented. The evaluated extreme values and the PSD characteristic of the random vibration responses of bridge and train are analyzed, and the influences of train speed and track irregularities (without earthquakes) on the random vibration characteristic of bridge and train are discussed.

Research on the relation the characteristics of the faculty and the commitment to continuous improvement of motivations and student study processes

Kun-Dang Chen,Ping-Kuo Chen 서울대학교 교육연구소 2017 Asia Pacific Education Review Vol.18 No.4

This study focused on China’s higher education system and explored if personality traits were a mediator of the relationship between motivational mechanisms and continuous improvement, and further explored if leadership change was a moderator of the relationship between personality traits and continuous improvement of the motivations and student study processes. In this paper, partial least squares (PLS) was the primary methodology used to test mediation and moderation. This study analysed 350 samples even though a large sample may cause an evaluative error in the mediation effect when using PLS. For this reason, we further adopted the Sobel test to verify this effect. According to the test results, in addition to motivational mechanisms having a positive effect on continuous improvement of the motivations and student study processes, personality traits are a mediator that influences the effect of motivational mechanisms on the continuous improvement of the motivations and student study processes. Furthermore, we proved that leadership change is a moderator between personality traits and continuous improvement of the motivations and student study processes. In addition, we discussed the relationship between mediation and moderation effects of different personality traits and leadership change.

Efficient and Selective Construction of Pyrrolo[3,2-d]pyrimidine Derivatives

Ping He,Jing Wu,Yang-Gen Hu,Zai-Fang Li,Qiu-Fei Hou,Yan-Ling Wang,Kun Zhao,Erli Zhang 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

An efficient and selective method for the synthesis of ethyl 2-amino/aryloxy-3-aryl-4-oxo-5-phenyl-4,5- dihydro-3H-pyrrolo[3,2-d]pyrimidine-7-carboxylate derivatives has been developed. The main process involved the reaction of diethyl 1-phenyl-3-((triphenylphosphoranylidene)amino)-1H-pyrrole-2,4-dicarboxylate and aromatic isocyanates, followed by addition of amines/phenols in the presence of catalytic amount of sodium ethoxide or solid potassium carbonate.

Modeling, analysis and optimization of adsorption parameters of Au(III) using low-cost agricultural residuals buckwheat hulls

Kun Deng,Ping Yin,Xiguang Liu,Qinghua Tang,Rongjun Qu 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

The agricultural residuals buckwheat hulls in the region of Jiaodong, China (BHJC) were employed to adsorb Au(III) ions both in the spiked samples and the gold-plating wastewater samples, and the relevant adsorption kinetics and isotherms were investigated. The investigation on the adsorption selectivity showed that BHJC displayed strong affinity for gold in the aqueous solutions. Furthermore, the process optimization was performed using response surface methodology (RSM), the quantitative relationship between the gold uptake and the different levels of experimental factors was used to work out optimized levels of these parameters.

High-gas pressure stabilization of the meta-stable magnetic hydrides, oxides, and nitrides

Ping-Zhan Si,Nai-Kun Sun,Chul-Jin Choi 한국자기학회 2016 한국자기학회 학술연구발표회 논문개요집 Vol.2016 No.11

Active control of a nonlinear and hysteretic building structure with time delay

Kun Liu,Long-Xiang Chen,Guo-Ping Cai 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.3

Time delay inevitably exists in active control systems, and it may cause the degradation of control efficiency or instability of the systems. So time delay needs to be compensated in control design in order to eliminate its negative effect on control efficiency. Today time delay in linear systems has been more studied and some treating methods had been worked out. However, there are few treating methods for time delay in nonlinear systems. In this paper, an active controller for a nonlinear and hysteretic building structure with time delay is studied. The nonlinear and hysteretic behavior of the system is illustrated by the Bouc-Wen model. By specific transformation and augmentation of state parameters, the motion equation of the system with explicit time delay is transformed into the standard state space representation without any explicit time delay. Then the fourth-order Runge-Kutta method and instantaneous optimal control method are applied to the controller design with time delay. Finally, numerical simulations and comparisons of an eight-story building using the proposed time-delay controller are carried out. Simulation results indicate that the control performance will deteriorate if time delay is not taken into account in the control design. The simulations also prove the proposed time delay controller in this paper can not only effectively compensate time delay to get better control effectiveness, but also work well with both small and large time delay problems.

Optimization Control Method of Intelligent Cooling and Lubrication for a Geared Spindle

Kun-Ying Li,Ping-Cheng Hsieh,Jen-Ji Wang,Shih-Jie Wei 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.10

The heat generated by the transmission system in the gear-driven spindle module of the machine tool not only influences the overall temperature field but also induces an excessive rise in temperature of gears tooth flank or rolling contact surface resulting in thermal deformation. In this study, high torque geared spindle was adopted to investigate a cooling control method, and an effective geared spindle cooling control method was proposed and tested. The controller of the cooling system received gear spindle load, rotational speed, and temperature of spindle to adjust the cooling flowrate, and the gas temperature of oil gas lubrication. Under spindle speed of 2000 rpm, the thermal deformations of X-axis, Y-axis, and Z-axis with cooling control are reduced by 43.7%, 46.8%, and 18.6%, respectively. The cooling control method not only can effectively control the rise in temperature of the meshing and contact friction area of the transmission system but also enables the transmission components and bearings of the geared spindle to achieve optimal cooling and lubrication effects.

Fermentation Quality of Alfalfa Silages Treated with Additives

Ping-Du Liu,Zhu Yu,Tao Shao,Kun Wang 한국초지조사료학회 2009 한국초지조사료학회 학술대회논문집 Vol.2009 No.08

Active control of a nonlinear and hysteretic building structure with time delay

Liu, Kun,Chen, Long-Xiang,Cai, Guo-Ping Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.3

Time delay inevitably exists in active control systems, and it may cause the degradation of control efficiency or instability of the systems. So time delay needs to be compensated in control design in order to eliminate its negative effect on control efficiency. Today time delay in linear systems has been more studied and some treating methods had been worked out. However, there are few treating methods for time delay in nonlinear systems. In this paper, an active controller for a nonlinear and hysteretic building structure with time delay is studied. The nonlinear and hysteretic behavior of the system is illustrated by the Bouc-Wen model. By specific transformation and augmentation of state parameters, the motion equation of the system with explicit time delay is transformed into the standard state space representation without any explicit time delay. Then the fourth-order Runge-Kutta method and instantaneous optimal control method are applied to the controller design with time delay. Finally, numerical simulations and comparisons of an eight-story building using the proposed time-delay controller are carried out. Simulation results indicate that the control performance will deteriorate if time delay is not taken into account in the control design. The simulations also prove the proposed time delay controller in this paper can not only effectively compensate time delay to get better control effectiveness, but also work well with both small and large time delay problems.

An evaluation on in-pile behaviors of SiC_f/SiC cladding under normal and accident conditions with updated FROBA-ATF code

Chen, Ping,Qiu, Bowen,Li, Yuanming,Wu, Yingwei,Hui, Yongbo,Deng, Yangbin,Zhang, Kun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.4

Although there are still controversial opinions and uncertainty on application of SiC_f/SiC composite cladding as next-generation cladding material for its great oxidation resistance in high temperature steam environment and other outstanding advantages, it cannot deny that SiC_f/SiC cladding is a potential accident tolerant fuel (ATF) cladding with high research priority and still in the engineering design stage for now. However, considering its disadvantages, such as low irradiated thermal conductivity, ductility that barely not exist, further evaluations of its in-pile behaviors are still necessary. Based on the self-developed code we recently updated, relevant thermohydraulic and mechanical models in FROBA-ATF were applied to simulate the cladding behaviors under normal and accident conditions in this paper. Even through steady-state performance analysis revealed that this kind of cladding material could greatly reduce the oxidation thickness, the thermal performance of UO₂-SiC was poor due to its low inpile thermal conductivity and creep rate. Besides, the risk of failure exists when reactor power decreased. With geometry optimization and dopant addition in pellets, the steady-state performance of UO₂-SiC was enhanced and the failure risk was reduced. The thermal and mechanical performance of the improved UO₂-SiC was further evaluated under Loss of coolant accident (LOCA) and Reactivity Initiated Accident (RIA) conditions. Transient results showed that the optimized ATF had better thermal performance, lower cladding hoop stress, and could provide more coping time under accident conditions.