A SPH-Lagrangian-Eulerian Approach for the Simulation of Concrete Gravity Dams under Combined Effects of Penetration and Explosion

Guangdong Yang,Gaohui Wang,Wenbo Lu,Peng Yan,Ming Chen,Xinxia Wu 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.8

The damage prediction of high dams under the attacks of earth-penetrating weapons has gained significant importance in recentyears. For this purpose, a SPH-Lagrangian-Eulerian coupled approach is proposed to describe the damage processes of concretegravity dams subjected to the combined action of the penetration and explosion. The SPH method is used to model the concretematerial with the large deformation near the penetration and explosion regions. The Lagrangian algorithm is adopted to simulate thehigh-velocity projectile and dam body with the small distortion. And the Eulerian algorithm is employed to describe the dynamicbehavior of the water and air media. The validity of the penetration model is calibrated against a previous penetration test. Meanwhile, the SPH-Lagrangian-Eulerian coupled method is verified by implementing an underwater explosion test in a concretecube. The computed distribution of cracking damage is consistent with the result of the experimental test, which validates the validityof the proposed SPH-Lagrangian-Eulerian coupling method. Subsequently, the penetration processes of a concrete gravity dam underthe high-velocity projectile are presented. After the rapid penetration, the explosives are detonated in the dam with the initialpenetration damage. The shock wave propagation characteristics in the dam and reservoir water are discussed. The failure processesand dynamic responses of the dam subjected to the combined action of the penetration and explosion are investigated. The influenceof the initial penetration damage and the reservoir water on the failure processes of the dam subjected to the internal blast loading is alsodiscussed. The results show that the penetration of the high-velocity projectile only causes a local damage to the concrete gravity dam. However, the combined effects of the penetration and explosion cause significantly more damage to the upper region of the dam.

A flexible piezoelectric-triboelectric hybrid nanogenerator in one structure with dual doping enhancement effects

Yang Xiude,Li Ping,Wu Bo,Li Hongwei,Zhou Guangdong 한국물리학회 2021 Current Applied Physics Vol.32 No.-

For achieving more effective mechanical energy conversion, based on low-cost and flexible polydimethylsiloxane (PDMS) and polyvinylidene fluoride (PVDF) polymer film as triboelectric and piezoelectric function layer respectively, a polymer-based hybrid piezoelectric-triboelectric nanogenerator (PT-NG) with a structure of Al/ PVDF/Cu-PDMS/indium tin oxide (ITO)/polyethylene terephthalate (PET) has been demonstrated. The device has realized the simultaneous triboelectric and piezoelectric conversions in one structure. In addition, when PDMS and PVDF are further modified by graphene quantum dot (GQD) and titanium dioxide (TiO2) nanoparticles respectively, both triboelectric and piezoelectric outputs of the modified device are greatly enhanced synchronously. The experimental results have indicated that the increase of triboelectric output is due to the improvement of dielectric properties of PDMS film doped with conductive GQDs as well as the enhancement of the effective contact caused by the change of PDMS surface microstructure. While the promotion of piezoelectric output is mainly attributed to the fact that PVDF film after TiO2 modification induces more polarized β phase with a polarization-free process. Accordingly, the modified device converts mechanical energy into electricity more effectively, which shows a promising prospect in the fields of flexibility display, electronic skin, wearable electronic products and self-powered sensors.

Pentacene as a hole transport material for high performance planar perovskite solar cells

Xiude Yang,Gang Wang,Debei Liu,Yanqing Yao,Guangdong Zhou,Ping Li,Bo Wu,Xi Rao,Qunliang Song 한국물리학회 2018 Current Applied Physics Vol.18 No.10

A cost-effective and efficient organic semiconductor pentacene was developed as a hole transport layer (HTL) material to replace classical PEDOT:PSS for planar perovskite solar cells (PSCs). As expected, the pentacene based device exhibits power conversion efficiency (PCE) of 15.90% (Jsc of 19.44 mA/cm2, Voc of 1.07 V, and FF of 77%), comparable to the PEDOT:PSS based device (PCE of 15.65%, Jsc of 18.78 mA/cm2, Voc of 1.07 V, and FF of 77%) under the same experimental conditions. The excellent performance of vacuum deposited pentacene is mainly attributed to the high efficient charge extraction and transfer in device due to the high-quality perovskite film grown on the top of pentacene substrate and a favorable energy-level alignment together with a desired downward band bending formed at the perovskite/pentacene interface. Our research has confirmed that pentacene could be served as a promising HTL material to achieve effective and potentially economical planar type PSCs.

The N, N-Dimethylformamide Annealing for Enhanced Performance of Perovskite Solar Cells Fabricated in Ambient Air

Xiude Yang,Debei Liu,Ping Li,Bo Wu,Haishen Huang,Tingyan Zhou,Guangdong Zhou 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.09

By adopting N, N-Dimethylformamide (DMF) atmosphere annealing at room temperature, planar perovskite solar cells with a p-i-n structure of ITO/PEDOT:PSS/Perovskite/PCBM/C60/Al are fabricated by a simple one-step solution process in ambient air with humidity around 50%, and the influence of DMF atmosphere on perovskite solar cells (PSCs) is systematically investigated. Compared to the reference device without DMF reaction, the perovskite films treated by modest DMF annealing show a better distribution and a higher densification, and thus the power conversion efficiency (PCE), short circuit current density (Jsc) and fill factor (FF) are increased by about 17%, 8% and 6%, respectively. This work displays the importance of solvent annealing for perovskite film prepared by the one-step spin-coating method, and possibly provides a simple and cost-effective way to efficiently fabricate PSCs in ambient air.

Statistical characteristics of sustained wind environment for a long-span bridge based on long-term field measurement data

Youliang Ding,Guangdong Zhou,Yang Deng,Aiqun Li 한국풍공학회 2013 한국풍공학회지 Vol.17 No.1

The fluctuating wind induced vibration is one of the most important factors which has been taken into account in the design of long-span bridge due to the low stiffness and low natural frequency. Field measurement characteristics of sustained wind on structure site can provide accurate wind load parameters for wind field simulation and structural wind resistance design. As a suspension bridge with 1490 m main span, the Runyang Suspension Bridge (RSB) has high sensitivity to fluctuating wind. The simultaneous and continuously wind environment field measurement both in mid-span and on tower top is executed from 2005 up to now by the structural health monitoring system installed on this bridge. Based on the recorded data, the wind characteristic parameters, including mean wind speed, wind direction, the turbulence intensity, the gust factors, the turbulence integral length, power spectrum and spatial correlation, are analyzed in detail and the coherence functions of those parameters are evaluated using statistical method in this paper. The results indicate that, the turbulence component of sustain wind is larger than extremely strong winds although its mean wind speed is smaller; the correlation between turbulence parameters is obvious; the power spectrum is special and not accord with the Simiu spectrum and von Karman spectrum. Results obtained in this study can be used to evaluate the long term reliability of the Runyang Suspension Bridge and provide reference values for wind resistant design of other structures in this region.

Mechanism analysis of switching direction transformation in an Er2O3 based RRAM device

Shuangsuo Mao,Guangdong Zhou,Bai Sun,Hosameldeen Elshekh,Xiaohua Zhang,Xiaohua Zhang,Feng Yang,Yong Zhao 한국물리학회 2019 Current Applied Physics Vol.19 No.12

The resistive random access memory (RRAM) based on resistive switching effect has considered to be the most advanced next generation memory, in which the switching direction determines the order of reading-writing. In this work, the rare-earth metal Er2O3 was used as functional layer, and Ag and indium-tin-oxide (ITO) are selected as top and bottom electrode to fabricate resistive switching device. Further, it is observed that the switching direction and memory window of resistive switching device can be regulated by exchanging top and bottom electrode. Moreover, the complementary switching memory behavior in Ag/Er2O3/ITO/Er2O3/Ag structure was also observed. Through mechanism analysis, it is expected that the barrier changes and metal-ions oxidation-reduction should be responsible for the conversion of switching direction and regulation of memory window. This work opens up a way to the development of next generation new concept memory.

Statistical characteristics of sustained wind environment for a long-span bridge based on long-term field measurement data

Ding, Youliang,Zhou, Guangdong,Li, Aiqun,Deng, Yang Techno-Press 2013 Wind and Structures, An International Journal (WAS Vol.17 No.1

The fluctuating wind induced vibration is one of the most important factors which has been taken into account in the design of long-span bridge due to the low stiffness and low natural frequency. Field measurement characteristics of sustained wind on structure site can provide accurate wind load parameters for wind field simulation and structural wind resistance design. As a suspension bridge with 1490 m main span, the Runyang Suspension Bridge (RSB) has high sensitivity to fluctuating wind. The simultaneous and continuously wind environment field measurement both in mid-span and on tower top is executed from 2005 up to now by the structural health monitoring system installed on this bridge. Based on the recorded data, the wind characteristic parameters, including mean wind speed, wind direction, the turbulence intensity, the gust factors, the turbulence integral length, power spectrum and spatial correlation, are analyzed in detail and the coherence functions of those parameters are evaluated using statistical method in this paper. The results indicate that, the turbulence component of sustain wind is larger than extremely strong winds although its mean wind speed is smaller; the correlation between turbulence parameters is obvious; the power spectrum is special and not accord with the Simiu spectrum and von Karman spectrum. Results obtained in this study can be used to evaluate the long term reliability of the Runyang Suspension Bridge and provide reference values for wind resistant design of other structures in this region.

Expressing a Modified Cowpea Trypsin Inhibitor Gene to Increase Insect Tolerance Against Pieris rapae in Chinese Cabbage

Xiaoli Ma,Zhen Zhu,Yane Li,Guangdong Yang,Yanxi Pei 한국원예학회 2017 Horticulture, Environment, and Biotechnology Vol.58 No.2

To increase the tolerance of Chinese cabbage (Brassica campestris L. ssp. pekinensis) to Pieris rapae, weintroduced a modified cowpea trypsin inhibitor (CpTI) gene, SCK, into various cultivars. SCK was derived fromCpTI, an insect-resistance gene. The protein accumulating capacity of CpTI can be improved by adding a signalpeptide sequence at the 5' end and an endoplasmic reticulum-detained signal sequence at the 3' end. Using an optimizedAgrobacterium tumefaciens-mediated transformation system in Chinese cabbage, we obtained a maximum transformationefficiency of ~6.83%. Insect resistance tests and CpTI enzymatic assays showed that most of the transgenic plantshad significant resistance to cabbage worm (Pieris rapae) larvae and that the plants with the highest levels of insectresistance had the greatest CpTI-related capacity, indicating a high correlation between SCK expression and insectresistance. An evaluation of segregation patterns in the independent transgenic line with the highest insect resistance,‘ZB-08-04’, showed that kanamycin resistant versus sensitive plants segregated in a 3:1 Mendelian fashion. This studyprovides a potential germplasm resource for Chinese cabbage breeding in the future.

Polymorphism of the Promoter Region of Hsp70 Gene and Its Relationship with the Expression of HSP70mRNA, HSF1mRNA, Bcl-2mrna and Bax-AMrna in Lymphocytes in Peripheral Blood of Heat Shocked Dairy Cows

Cai, Yafei,Liu, Qinghua,Xing, Guangdong,Zhou, Lei,Yang, Yuanyuan,Zhang, Lijun,Li, Jing,Wang, Genlin Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.5

The blood samples were collected from dairy cows at the same milking stage. The single-strand conformation polymorphism (PCR-SSCP) method was used to analyze for polymorphism at the 5'flanking region of the hsp70 gene. The mRNA expression levels of HSP70, HSF1, Bcl-2 and Bax-$\alpha$ at different daily-mean-temperature were analyzed by relative quantitative RTPCR. The DNA content, cell phase and the ratio of apoptosis of lymphocytes in peripheral blood of dairy cattle at different daily-meantemperature were determined by FCM. The PCR-SSCP products of primer pair 1 showed polymorphisms and could be divided into four genotypes: aa, ab, ac, cc, with the cis-acting element (CCAAT box) included. Mutations in the hsp70 5'flanking region (468-752 bp) had different effects on mRNA expression of HSP70, HSF1, Bcl-2 and Bax-$\alpha$. The ac genotypic cows showed higher expressions of HSP70mRNA, HSF1mRNA and Bcl-2mRNA/Bax-$\alpha$mRNA and lower ratio of apoptosis. These mutation sites can be used as molecular genetic markers to assist selection for anti-heat stress cows.

Analysis of Toe Formation in Stress-Concentration Zones on High Rock Slopes

Ke Deng,Ming Chen,Peng Yan,Zhendong Leng,Guangdong Yang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.2

Toe formation is a phenomenon resulting from unconnected cracks between blastholes,which occurred during blasting excavation of the abutment slot at Baihetan hydropower station. Analysis of crack development has tended not to focus on the high in-situ stress environment at the slope corner. Therefore, this study aimed to explore the toe formation process through theoretical analysis and numerical simulation. Firstly, a three-blasthole model was established to analyze the effects of blasting load and in-situ stress on crack extension. Then, a finite-element model of the abutment slot was built to simulate crack propagationunder different in-situ stress environment. Finally, optimization measures for avoiding toe were proposed. The results demonstrate that cracks grow preferentially in the direction of the maximum tangential tensile stress and are influenced by the blasting load and in-situ stress. On the lateral side of the abutment slot, the crack initiation and extension occur far from the centerline due to the deviation of the maximum tangential tensile stress. The deviation increased as the in-situ stress. Consequently, cracks between blastholes not being able to connect with each other results in toe formation. Increment of the linear density of the charge and optimization of the excavated profile are both effective in reducing the impact of the stress concentration caused by in-situ stress and preventing toe formation.