Load-transferring mechanism and evaluation theory of bolt with single and double nut fasteners

Qiyu Li,Dachang Zhang,Hao Xu,Yibi Li,Weiqun Chen,Kaixuan Zhang 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.2

The use of the ordinary double nut (i.e., ODN) composed of a master nut (i.e., M-nut) and a slave nut (i.e., S-nut) is a highly efficient method to prevent bolts loosening. A novel double nut (i.e., FODN) composed of a master nut (i.e., M-nut) and flat slave nut (i.e., FS-nut) is proposed to save raw materials. The bolt fastening tests with single nut, ODN and FODN are performed to investigate the preload and counterbalance forces. Corresponding finite element analysis (FEA) models are established and validated by comparing the preload with the experimental results. The load-bearing capacity, the extrusion effect, and the contact stress of each engaged thread for ODN and FODN are observed by FEA. The experimental and simulated results revealed that the bolt fastening with double-nut has different load-transferring mechanisms from single-nut. Nevertheless, for double-nut/bolt assemblies, the FS-nut can provide load transfer that is like that of the S-nut, and the FODN is a reasonable and reliable fastening method. Furthermore, based on the theory of Yamamoto, a formula considering the extrusion effect is proposed to calculate the preload distribution of the double-nut, which is applicable to varying thicknesses of slave-nuts in double-nut/bolt assemblies.

Fuzzy system and Improved APIT (FIAPIT) combined range-free localization method for WSN

( Xiaofeng Li ),( Liangfeng Chen ),( Jianping Wang ),( Zhong Chu ),( Qiyue Li ),( Wei Sun ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.7

Among numerous localization schemes proposed specifically for Wireless Sensor Network (WSN), the range-free localization algorithms based on the received signal strength indication (RSSI) have attracted considerable research interest for their simplicity and low cost. As a typical range-free algorithm, Approximate Point In Triangulation test (APIT) suffers from significant estimation errors due to its theoretical defects and RSSI inaccuracy. To address these problems, a novel localization method called FIAPIT, which is a combination of an improved APIT (IAPIT) and a fuzzy logic system, is proposed. The proposed IAPIT addresses the theoretical defects of APIT in near (it`s defined as a point adjacent to a sensor is closer to three vertexes of a triangle area where the sensor resides simultaneously) and far (the opposite case of the near case) cases partly. To compensate for negative effects of RSSI inaccuracy, a fuzzy system, whose logic inference is based on IAPIT, is applied. Finally, the sensor`s coordinates are estimated as the weighted average of centers of gravity (COGs) of triangles` intersection areas. Each COG has a different weight inferred by FIAPIT. Numerical simulations were performed to compare four algorithms with varying system parameters. The results show that IAPIT corrects the defects of APIT when adjacent nodes are enough, and FIAPIT is better than others when RSSI is inaccuracy.

Prediction Model for Disc Cutter Wear of TBM in Sandy Cobble Strata

Yitao Li,Honggui Di,Qiyu Yao,Longlong Fu,Shunhua Zhou 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.3

The disc cutter of tunnel boring machines (TBMs) intended for sandy cobble strata undergoes severe wear, which significantly increases the cost and construction period. Currently, there is no wear prediction model for disc cutters in the case of sandy cobble strata. This paper proposes a wear prediction model for disc cutters of a TBM operated in sandy cobble strata. A wear rate expression is determined based on the theory of tribology. A quantitative relationship between the wear coefficient and the particle size parameters (Cu and d60) is established. The strength of the cobbles and the motion track and outline of the disc cutter are considered in the model. The model is validated using field data from two cases. The effect of grain distribution is considered in the proposed model, unlike that in existing prediction models, thus offering a more effective approach in predicting the wear of disc cutters intended for sandy cobble strata.

Research on the Theories and Practice of Sports Event Culture Construction in China

( Hongjiang Li ),( Qingwei Wang ),( Rufeng Su ),( Fang Wang ),( Qiyue Chen ),( Xuecui Bi ) 한국체육학회 2015 국제스포츠과학 학술대회 Vol.2015 No.1

Comparative Study on Microstructure and Aluminum Distribution Between Laser Beam Welding and Electron Beam Welding of Ti–6Al–4V Alloy Plates

Hengchang Bu,Qiyu Gao,Yun Li,Feiyun Wang,Xiaohong Zhan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

Ti–6Al–4V alloy plates with a thickness of 4 mm were joined by electron beam welding (EBW) and laser beam welding(LBW). The comparison of LBW and EBW was performed according to grain morphology, microstructure, aluminum distribution,and microhardness of the joints. Results indicate that compared with LBW joint, more equiaxed grains are observedaround the central zone of the EBW joint. The microstructure in fusion zone (FZ) of EBW joint presents more uneven withobviously coarser acicular martensite α′. Moreover, the aluminum element content of EBW joint is substantially lower,which demonstrates a more significant burning loss behavior in EBW process. The lower aluminum content in the uppercenter areas of the joints is attributed to the more significant element burning loss caused by higher temperature, whereasmore uniform aluminum distribution in the upper part of the joints is ascribed to stronger convection form within the upperpart of the joint. In addition, the characteristics of convection and thermal field within the molten pool are recognized asvital factors influencing the aluminum distribution. The lower microhardness profile in FZ of the EBW joint is principallyattributed to coarser acicular martensite α′ and lower aluminum element in EBW joint.

Inhibition of chromosomal region maintenance 1 suppresses the migration and invasion of glioma cells via inactivation of the STAT3/MMP2 signaling pathway

Qianqian Shan,Shengsheng Li,Qiyu Cao,Chenglong Yue,Mingshan Niu,Xiangyu Chen,Lin Shi,Huan Li,Shangfeng Gao,Jun Liang,Rutong Yu,Xuejiao Liu 대한생리학회-대한약리학회 2020 The Korean Journal of Physiology & Pharmacology Vol.24 No.3

Chromosomal region maintenance 1 (CRM1) is associated with an adverse prognosis in glioma. We previously reported that CRM1 inhibition suppressed glioma cell proliferation both in vitro and in vivo. In this study, we investigated the role of CRM1 in the migration and invasion of glioma cells. S109, a novel reversible selective inhibitor of CRM1, was used to treat Human glioma U87 and U251 cells. Cell migration and invasion were evaluated by wound-healing and transwell invasion assays. The results showed that S109 significantly inhibited the migration and invasion of U87 and U251 cells. However, mutation of Cys528 in CRM1 abolished the inhibitory activity of S109 in glioma cells. Furthermore, we found that S109 treatment decreased the expression level and activity of MMP2 and reduced the level of phosphorylated STAT3 but not total STAT3. Therefore, the inhibition of migration and invasion induced by S109 may be associated with the downregulation of MMP2 activity and expression, and inactivation of the STAT3 signaling pathway. These results support our previous conclusion that inhibition of CRM1 is an attractive strategy for the treatment of glioma.

Compound-Type Hybrid Energy Storage System and Its Mode Control Strategy for Electric Vehicles

Bin Wang,Jun Xu,Binggang Cao,Qiyu Li,Qingxia Yang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

This paper proposes a novel compound-type hybrid energy storage system (HESS) that inherits the unique advantages of both battery/supercapacitor (SC) and the SC/battery HESSs for electric vehicles (EVs). Eight operation modes are designed to match this system. A mode control strategy is developed for this HESS on the basis of these modes, and five classes of operation modes are established to simplify this strategy. The mode control strategy focuses on high operating efficiency and high power output. Furthermore, the compound-type HESS is designed such that the SC is the main priority in braking energy absorption. Thus, this HESS can operate efficiently and extend battery life. Simulation results also show that the compound-type HESS can not only supply adequate power to the motor inverter but can also determine suitable operation modes in corresponding conditions. Experimental results demonstrate that this HESS can extend battery life as well. The overall efficiency of the compound-type HESS is higher than those of the battery/SC and the SC/battery HESSs.

Compound-Type Hybrid Energy Storage System and Its Mode Control Strategy for Electric Vehicles

Wang, Bin,Xu, Jun,Cao, Binggang,Li, Qiyu,Yang, Qingxia The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.3

This paper proposes a novel compound-type hybrid energy storage system (HESS) that inherits the unique advantages of both battery/supercapacitor (SC) and the SC/battery HESSs for electric vehicles (EVs). Eight operation modes are designed to match this system. A mode control strategy is developed for this HESS on the basis of these modes, and five classes of operation modes are established to simplify this strategy. The mode control strategy focuses on high operating efficiency and high power output. Furthermore, the compound-type HESS is designed such that the SC is the main priority in braking energy absorption. Thus, this HESS can operate efficiently and extend battery life. Simulation results also show that the compound-type HESS can not only supply adequate power to the motor inverter but can also determine suitable operation modes in corresponding conditions. Experimental results demonstrate that this HESS can extend battery life as well. The overall efficiency of the compound-type HESS is higher than those of the battery/SC and the SC/battery HESSs.

DC Bus Voltage Stabilization Control Considering Power Loss of the Full-Quadrant Operated Inverter

Shi Jingkui,Huang Wenxin,Zheng Xinxin,Li Qiyue 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

This paper proposed a DC bus voltage stabilization control strategy of the full-quadrant operated three-phase grid-connected inverter, of which the reactive current is not 0. The strategy considers the power loss of the switches caused by both active and reactive current, which would aff ect the dynamic performance of voltage loop. In this condition, the power loss can be seen as a disturbance of the voltage loop so it should be taken into consideration in the design process. Besides, the voltage loop is the outer loop of the active current loop. The active and reactive current are coupled because of the coordinate transformation. As a result, the interference of the reactive current would aff ect the DC bus voltage through current coupling. The proposed control strategy considers the power loss and designs the outer voltage loop. Also the decoupling current controller based on complex vectors is discussed. With the proposed DC bus voltage stabilization strategy, the inverter can realize good dynamic and static performances. The control principle is analyzed in detail. The design of the control loops are discussed. The infl uences of the reactive current on the DC voltage and active current are analyzed. Finally, the simulation and experimental results verify the theoretical analysis.

Current Decoupling Scheme of Three-Phase Inverter with Complex Coefficient Controller

Zheng Xinxin,Xu Jianjun,Shi Jingkui,Huang Wenxin,Li Qiyue 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

In the control of three-phase system, AC signals are always changed into DC signals by synchronous coordinate transformation. A decoupling control scheme in the dq synchronous reference frame (SRF) is proposed to realize active and reactive current decoupling of three-phase inverter. The complex vector control model is established in SRF. Diff erent from the model established in static reference frame, the SRF control model can refl ect the coupling characteristic of the active and reactive current. As a result, the PI controller with complex coeffi cient can be applied to realize current decoupling. In this paper, the coupling characteristic of three-phase system is analyzed. A novel complex PI controller design method is proposed based on the SRF control model and the coeffi cients are calculated. And its implementation in the control loop is given. Compared with existing PI controllers with real or complex coeffi cients, the proposed complex PI controller can realize completely the decoupling of the active and reactive current in three-phase system. Besides, the control scheme can make current loop fulfi ll the expected symmetrical bandwidth, so as to realize a higher eff ective set-off frequency. As a result, the inverter can achieve well dynamic performance. Finally, the simulation and experimental results are given to verify the theoretical analysis.