Damage Mechanism of Drift Ice Impact

Li Gong,Zhonghui Wang,Yaxian Li,Chunling Jin,Jing Wang 한국정보처리학회 2019 Journal of information processing systems Vol.15 No.6

The ice damage occurs frequently in cold and dry region of western China in winter ice period and spring thawperiod. In the drift ice condition, it is easy to form different extrusion force or impact force to damage tunnellining, causing project failure. The failure project could not arrive the original planning and construction goal,giving rise to the water allocation pressure which influences diversion irrigation and farming production inspring. This study conducts the theoretical study on contact-impact algorithm of drift ices crashing diversiontunnel based on the symmetric penalty function in finite element theory. ANSYS/LS-DYNA is adopted as theplatform to establish tunnel model and drift ice model. LS-DYNA SOLVER is used as the solver and LSPREPOSTis used to do post-processing, analyzing the damage degrees of drift ices on tunnel. Constructingphysical model in the experiment to verify and reveal the impact damage mechanism of drift ices on diversiontunnel. The software simulation results and the experiment results show that tunnel lining surface will formvarying degree deformation and failure when drift ices crash tunnel lining on different velocity, different plansize and different thickness of drift ice. The researches also show that there are damages of drift ice impact forceon tunnel lining in the thawing period in cold and dry region. By long time water scouring, the tunnel liningsurfaces are broken and falling off which breaks the strength and stability of the structure.

Damage Mechanism of Drift Ice Impact

Gong, Li,Wang, Zhonghui,Li, Yaxian,Jin, Chunling,Wang, Jing Korea Information Processing Society 2019 Journal of information processing systems Vol.15 No.6

The ice damage occurs frequently in cold and dry region of western China in winter ice period and spring thaw period. In the drift ice condition, it is easy to form different extrusion force or impact force to damage tunnel lining, causing project failure. The failure project could not arrive the original planning and construction goal, giving rise to the water allocation pressure which influences diversion irrigation and farming production in spring. This study conducts the theoretical study on contact-impact algorithm of drift ices crashing diversion tunnel based on the symmetric penalty function in finite element theory. ANSYS/LS-DYNA is adopted as the platform to establish tunnel model and drift ice model. LS-DYNA SOLVER is used as the solver and LS-PREPOST is used to do post-processing, analyzing the damage degrees of drift ices on tunnel. Constructing physical model in the experiment to verify and reveal the impact damage mechanism of drift ices on diversion tunnel. The software simulation results and the experiment results show that tunnel lining surface will form varying degree deformation and failure when drift ices crash tunnel lining on different velocity, different plan size and different thickness of drift ice. The researches also show that there are damages of drift ice impact force on tunnel lining in the thawing period in cold and dry region. By long time water scouring, the tunnel lining surfaces are broken and falling off which breaks the strength and stability of the structure.

Blasting wave pattern recognition based on Hilbert-Huang transform

Li, Xuelong,Wang, Enyuan,Li, Zhonghui,Bie, Xiaofei,Chen, Liang,Feng, Junjun,Li, Nan Techno-Press 2016 Geomechanics & engineering Vol.11 No.5

Rockburst is becoming more serious in Chinese coal mine. One of the effective methods to control rockburst is blasting. In the paper, we monitored and analyzed the blasting waves at different blast center distances by the Hilbert-Huang transform (HHT) in a coal mine. Results show that with the increase of blast center distance, the main frequency and amplitude of blasting waves show the decreasing trend. The attenuation of blasting waves is slower in the near blast field (10-75 m), compared with the far blast field (75-230 m). Besides, the frequency superposition phenomenon aggravates in the far field. A majority of the blasting waves energy at different blast center distances is concentrated around the IMF components 1-3. The instantaneous energy peak shows attenuation trend with the blast center distance increase, there are two obvious energy peaks in the near blast field (10-75 m), the energy spectrum appears "fat", and the total energy is greater. By contrast, there is only an energy peak in the far blast field, the energy spectrum is "thin", and the total energy is lesser. The HHT three dimensional spectrum shows that the wave energy accumulates in the time and frequency with the increasing of blast center distance.

EMR: An effective method for monitoring and warning of rock burst hazard

Song, Dazhao,Wang, Enyuan,Li, Zhonghui,Qiu, Liming,Xu, Zhaoyong Techno-Press 2017 Geomechanics & engineering Vol.12 No.1

Rock burst may cause serious casualties and property losses, and how to conduct effective monitoring and warning is the key to avoid this disaster. In this paper, we reviewed both the rock burst mechanism and the principle of using electromagnetic radiation (EMR) from coal rock to monitor and forewarn rock burst, and systematically studied EMR monitored data of 4 rock bursts of Qianqiu Coal Mine, Yima Coal Group, Co. Ltd. Results show that (1) Before rock burst occurrence, there is a breeding process for stress accumulation and energy concentration inside the coal rock mass subject to external stresses, which causes it to crack, emitting a large amount of EMR; when the EMR level reaches a certain intensity, which reveals that deformation and fracture inside the coal rock mass have become serious, rock burst may occur anytime and it's necessary to implement an early warning. (2) Monitored EMR indicators such as its intensity and pulses amount are well and positively correlated before rock bursts occurs, generally showing a rising trend for more than 5 continuous days either slowly or dramatically, and the disaster bursts generally occurs at the lower level within 48 h after reaching its peak intensity. (3) The rank of EMR signals sensitive to rock burst in a descending order is maximum EMR intensity > rate of change in EMR intensity > maximum amount of EMR pulses > rate of change in the amount of EMR pulses.

Cardanol with a Covalently Attached Organophosphate Moiety as a Halogen-Free, Intrinsically Flame-Retardant PVC Bio-Plasticizer

Delong Hou,Songhang Wang,Jinming Chang,Zhou Xu,Qi Zeng,Zhonghui Wang,Yongcheng Yang,Jun Yan,Yi Chen 한국섬유공학회 2020 Fibers and polymers Vol.21 No.8

Plasticizers that enable flexible polyvinyl chloride (PVC) are usually combustible, restricting the application ofPVC in fire-prone scenarios. In this context, intrinsically flame-retardant plasticizers displaying dual function continue to bethe focus of intensive research. Despite their efficiency, the majority of these dual-functional plasticizers previously reportedcontain halogen elements, which, once ignited, emanate toxic and potentially carcinogenic substances, along with toxic gasesand smoke, polluting the environment, damaging the biota, and threatening human health. Here, we report a strategy to obtaina halogen-free, intrinsically flame-retardant PVC bio-plasticizer that harnesses the phenolic hydroxyl of naturally occurringcardanol and covalent attachment of an organophosphate moiety. When combined with di-(2-ethylhexyl) phthalate (DOP),the organophosphate-containing cardanol is qualified as a co-plasticizer, while endowing the PVC materials with flameretardancy. Unlike inorganic flame-retardants, the engineered cardanol is compatible with PVC such that the mechanicalproperties of the PVC materials are not compromised. The rationale underlying the present effort may provide guidance fordeveloping sustainable alternatives to halogen-containing plasticizers to address the sustainability challenge now confrontingPVC industry.

Load-Balancing Rendezvous Approach for Mobility-Enabled Adaptive Energy-Efficient Data Collection in WSNs

( Jian Zhang ),( Jian Tang ),( Zhonghui Wang ),( Feng Wang ),( Gang Yu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.3

The tradeoff between energy conservation and traffic balancing is a dilemma problem in Wireless Sensor Networks (WSNs). By analyzing the intrinsic relationship between cluster properties and long distance transmission energy consumption, we characterize three node sets of the cluster as a theoretical foundation to enhance high performance of WSNs, and propose optimal solutions by introducing rendezvous and Mobile Elements (MEs) to optimize energy consumption for prolonging the lifetime of WSNs. First, we exploit an approximate method based on the transmission distance from the different node to an ME to select suboptimal Rendezvous Point (RP) on the trajectory for ME to collect data. Then, we define data trans-mission routing sequence and model rendezvous planning for the cluster. In order to achieve optimization of energy consumption, we specifically apply the economic theory called Di-minishing Marginal Utility Rule (DMUR) and create the utility function with regard to energy to develop an adaptive energy consumption optimization framework to achieve energy effi-ciency for data collection. At last, Rendezvous Transmission Algorithm (RTA) is proposed to better tradeoff between energy conservation and traffic balancing. Furthermore, via collabo-rations among multiple MEs, we design Two-Orbit Back-Propagation Algorithm (TOBPA) which concurrently handles load imbalance phenomenon to improve the efficiency of data collection. The simulation results show that our solutions can improve energy efficiency of the whole network and reduce the energy consumption of sensor nodes, which in turn prolong the lifetime of WSNs.

Life Estimation Correction Model for Offshore Wind Power Transformer Based on Fault Tree Theory

Zhong Hui,Wang Runze,Zhang Li,Sun Youliang 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

The occurrence of fault would greatly afect the remaining life of ofshore wind power transformer. In this paper, the fault events during the operation of the ofshore power transformer were analyzed based on the fault tree theory and the structure function of the transformer fault event was established with considering the operation environment to propose the risk model of transformer fault events. The Monte Carlo method was used to sample the risk model, and the fault risk coefcient of the operation for the ofshore transformer was obtained. Taking the infuence of fault events into the remaining life of the transformer, a Life estimation correction model for ofshore wind power transformer was established, which provides guidance for the optimal design and early fault warning of ofshore transformers.