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Micromechanical modeling of hollow cylinder torsional shear test on sand using discrete element method

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JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING 2024年第12期16卷 5193-5208页

作者： Song, Shunxiang wang, pei Yin, Zhenyu Cheng, Yi Pik East China Jiaotong Univ Inst Geotech Engn Sch Civil Engn & Architecture Nanchang Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China UCL Dept Civil Environm & Geomatic Engn London England

Previous studies on the hollow cylinder torsional shear test (HCTST) have mainly focused on the macroscopic behavior, while the micromechanical responses in soil specimens with shaped particles have rarely been investigated. This paper develops a numerical model of the HCTST using the discrete element method (DEM). The method of bonded spheres in a hexagonal arrangement is proposed to generate flexible boundaries that can achieve real-time adjustment of the internal and external cell pressures and capture the inhomogeneous deformation in the radial direction during shearing. Representative angular particles are selected from Toyoura sand and reproduced in this model to approximate real sand particles. The model is then validated by comparing numerical and experimental results of HCTSTs on Toyoura sand with different major principal stress directions. Next, a series of HCTSTs with different combinations of major principal stress direction (a) and intermediate principal stress ratio (b) is simulated to quantitatively characterize the sand behavior under different shear conditions. The results show that the shaped particles are horizontally distributed before shearing, and the initial anisotropic packing structure further results in different stress-strain curves in cases with different a and b values. The distribution of force chains is affected by both a and b during the shear process, together with the formation of the shear bands in different patterns. The contact normal anisotropy and contact force anisotropy show different evolution patterns when either a orb varies, resulting in the differences in the non-coaxiality and other macroscopic responses. This study improves the understanding of the macroscopic response of sand from a microscopic perspective and provides valuable insights for the constitutive modeling of sand. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the

关键词： Sand Hollow cylinder torsional shear test (HCTST) Discrete element method (DEM) Principal stress rotation Micromechanics Anisotropy

EXPERIMENTAL STUDY ON SEDIMENT RESUSPENSION IN TAIHU LAKE UNDER DIFFERENT HYDRODYNAMIC DISTURBANCES

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Journal of Hydrodynamics 2011年第6期23卷 826-833页

作者： QIAN Jin ZHENG Sha-sha wang pei-fang wang Chao Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes Ministry of Education and College of Enviroment Hohai University Nanjing 210098 China

Contaminants resuspension in sediments induced by wind-wave could influence the water quality in shallow lakes. Resuspension of surface sediments from the Zhushan Bay, Taihu Lake was simulated under different wind forcing by using a pneumatic annular flume in this study. Acoustic Doppler Velocimeter （ADV） was used to measure flow velocity at each wind speed, and the characteristics of sediment resuspension were studied with the layered sampling technology. The experimental results show that the flow velocity increases with wind speed obviously and 6m/s is a critical wind speed which affected hydrodynamic conditions significantly. The distribution of flow velocity and water depth is different from that in ordinary open channel. With the enhanced hydrodynamic factors, the Suspended Solids Concentration （SSC） in water increases accordingly, and the incipient velocity of sediment resuspension is about 0.21 m/s. Based on the analysis of wind speed and average SSC in water column, the quantitative relationship is obtained. The SSC of the bottom layer is higher than the content of surface layer under different hydrodynamic conditions, and there are similar distributions between SSC and flow velocity in different water layers.

关键词： hydrodynamic disturbance sediment resuspension wind speed flow velocity

The application of environmental economics in marine functional zoning and coastal city conceptual planning

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Ecological Economy 2007年第4期3卷 425-433页

作者： wang pei＇er Environmentol Science Research Center Xiamen University Xiamen 361005P.R.China

There are a lot of functions of marine resources. The various and competing conflicts between different users and different sectors in the use of marine resources will cause the disorderly development of marine resources, and even destroy the marine ecosystem. Marine functional zoning is an effective tool to solve the conflicts. However, there are some shortcomings in the current understanding on marine functional zoning and its practice. In this paper, a case study on the resource-oriented marine functional zoning of Xiangshan Port is introduced. By the principles of resource-oriented and public participation, Xiangshan Port is divided into seven zones, and the main function of the whole port and seven zones are determined by the environmental economics analysis. A case study of Xiamen is also introduced for how to integrate marine functional zoning into a coastal city conceptual planning. Under the conservation principle, resources-oriented principle and so on, the advantages and disadvantages of natural ecosystem, social ecosystem and economic ecosystem are holistically analyzed, the urban orientation of Xiamen is determined as a regional international tourism city, and the whole city is divided into five function zones according to its leading industry -tourism. Resource-oriented marine functional zoning has a long-term guidance for sustainable use of marine resources and development strategy of a coastal city. And environmental economics analysis is an effective tool for resource-orientation.

关键词： Marine functional zoning Resource-ariented Environmental economics analysis

Species authentication and geographical origin discrimination of herbal medicines by near infrared spectroscopy:A review

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Journal of Pharmaceutical Analysis 2015年第5期5卷 277-284页

作者： pei wang Zhiguo Yu School of Pharmacy Shenyang Pharmaceutical University Center for Excellence in Post-Harvest Technologies North Carolina Agricultural and Technical State UniversityNorth Carolina Research Campus

Near infrared （NIR） spectroscopy as a rapid and nondestructive analytical technique, integrated with chemometrics, is a powerful process analytical tool for the pharmaceutical industry and is becoming an attractive complementary technique for herbal medicine analysis. This review mainly focuses on the recent applications of NIR spectroscopy in species authentication of herbal medicines and their geo- graphical origin discrimination.

关键词： Near infrared spectroscopyHerbal medicineSpecies authenticationGeographical origin discriminationQuality control

Prediction for the Multi-band Afterglows of FRB 200428 and its Implication

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Research in Astronomy and Astrophysics 2023年第11期23卷 84-89页

作者： Mei Du Shuang-Xi Yi Can-Min Deng pei wang School of Physics and Physical Engineering Qufu Normal UniversityQufu 273165China Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China

The physical mechanism of fast radio bursts(FRBs) is still unknown. On 2020 April 28, a special radio burst, FRB200428, was detected and believed to be associated with the Galactic magnetar SGR 1935+2154. It confirms that at least some of the FRBs were generated by magnetars, although the radiation mechanism continues to be *** this end, we study in detail the multiband afterglows of FRB 200428 described by the synchrotron fireball shock model. We find the prediction for the optical and radio afterglows of FRB 200428 is consistent with the observations when considering the post-FRB optical and radio upper limits from the literature. We also show that the follow up detection of the afterglows from fast radio bursts like—FRB 200428 is possible at the radio band,though challenging. Based on our model, one can obtain information about the energy of the fireball, the radiation zone, and the nature of the surrounding medium. That may shed light on the physical mechanism of FRBs.

关键词： stars:magnetars (stars:)gamma-ray bursts:general radiation mechanisms:non-thermal

Versatile physiological functions of the Nudix hydrolase family in berry development and stress response in grapevine

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Journal of Integrative Agriculture 2022年第1期21卷 91-112页

作者： wang pei-pei wang Zhao-ke GUAN Le Muhammad Salman HAIDER Maazullah NASIM YUAN Yong-bing LIU Geng-sen LENG Xiang-peng Institute of Grape Science and Engineering College of HorticultureQingdao Agricultural UniversityQingdao 266109P.R.China College of Horticulture Nanjing Agricultural UniversityNanjing 210095P.R.China Qingdao Key Laboratory of Modern Agriculture Quality and Safety Engineering College of HorticultureQingdao Agricultural UniversityQingdao 266109P.R.China

Nudix hydrolases are widely distributed across all classes of organisms and provide the potential capacity to hydrolyze a wide range of organic pyrophosphates. Although Nudix hydrolases are involved in plant detoxification processes in response to abiotic and biotic stresses, the biological functions of Nudix hydrolases remain largely unclear in *** the present study, a total of 25 putative grapevine Nudix hydrolases(VvNUDXs) were identified by bioinformatics analysis and classified into eight subfamilies based to their preferred substrates. Both tandem and segmental duplications were responsible for the evolution and expansion of the NUDX gene family in grapevine. To investigate the regulatory roles of VvNUDX genes during growth and development, as well as in response to abiotic and biotic stresses in grapevine, the expression patterns were revealed in publicly available microarray data. The spatial and temporal expression patterns of the VvNUDX genes indicated that they might play important roles in multiple developmental processes. Transcriptome and qRT-PCR analyses showed that ten VvNUDX genes were specifically expressed in grapevine berries, suggesting potential roles in grapevine berry development. Expression and phylogenetic analyses demonstrated that VvNUDX1 and VvNUDX3 might be involved in terpenoid biosynthesis in grapevine. Furthermore,most VvNUDX genes active toward the ADP-ribose/NADH showed different patterns in response to various abiotic and biotic stresses, such as salinity and drought, as well as different types of biotic treatments, such as Erysiphe necator,Bois Noir phytoplasma and leaf-roll-associated virus-3(GLRaV-3). These results indicated that VvNUDX genes were associated with plant detoxification processes in response to abiotic and biotic stresses, and regulate the disease immunity and resistance pathways. The information obtained here may provide good opportunities to explore the physiological functions of VvNUDX genes in berry d

关键词： grapevine NUDX gene expression berry development stress response

Evolutionary genetics of wheat mitochondrial genomes

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The Crop Journal 2023年第6期11卷 1774-1781页

作者： Hui-Lin Hu Fan Zhang pei wang Fu-Hao Lu State Key Laboratory of Crop Stress Adaptation and Improvement School of Life SciencesHenan UniversityKaifeng 475004HenanChina Henan Key Laboratory of Big Data Analysis and Processing School of Computer and Information EngineeringHenan UniversityKaifeng 475004HenanChina School of Mathematics and Statistics Henan UniversityKaifeng 475004HenanChina

The Triticum-Aegilops complex provides ideal models for the study of polyploidization,and mitochondrial genomes(mtDNA)can be used to trace cytoplasmic inheritance and energy production following *** this study,gapless mitochondrial genomes for 19 accessions of five Triticum or Aegilops species were *** genomics confirmed that the BB-genome progenitor donated mtDNA to tetraploid ***(genome formula AABB),and that this mtDNA was then passed on to the hexaploid ***(AABBDD).T urartu(AA)was the paternal parent of ***(AAGG),and an earlier ***(DD)was the maternal parent of ***(CCDD).Genic sequences were highly conserved within species,but frequent rearrangements and nuclear or chloroplast DNA insertions occurred during *** highly variable mitochondrial genes(atp6,cob,nad6,and nad9)were established as marker genes for Triticum and Aegilops species *** BB/GG-specific atp6 and cob genes,which were imported from the nuclear genome,could facilitate identification of their diploid *** haplotypes and repeat-sequence patterns indicated that BB was much closer to GG than to ***(SS).These findings provide novel insights into the polyploid evolution of the Triticum/Aegilops complex from the perspective of mtDNA,advancing understanding of energy supply and adaptation in wheat species。

关键词： Wheat Mitochondrion mtDNA Comparative genomics Polyploidization

Fast Moving Object Extraction in H.264/AVC Compressed Domain

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Journal of Electronics(China) 2010年第6期27卷 801-807页

作者： wang pei Wu Zhixia College of Information Mechanical ＆ Electrical Engineering Shanghai Normal University Shanghai 200234 China

This paper presents a novel approach for moving object extraction in the H.264/AVC compressed domain, which based on Ant Colony clustering Algorithm (ACA) and threshold method in macro block layer. Firstly, the Motion Vector (MV) field and the macro block types are extracted from the H.264/AVC compressed video, and then merge MVs with the same characteristic. Secondly, an improved ACA is used to classify the MV field into different motion homogenous regions. At the same time, use macro block types to determine the location of objects. Finally, using the complementarities of macro block template and MVs clustering template to obtain final objects. Experimental results for several video sequences demonstrate that in the case of ensuring accuracy, the proposed approach can extract moving object faster.

关键词： H.264/AVC Moving object extraction Motion Vector (MV)

Control performance and energy saving of multi-level pressure switching control system based on independent metering control

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High Technology Letters 2020年第2期26卷 224-234页

作者： Cao Xiaoming Yao Jing Sha Tong wang pei College of Mechanical Engineering Yanshan UniversityQinhuangdao 066004P.R.China School of Mechanical Engineering Nanjing Institute of TechnologyNanjing 210000P.R.China

Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure switching control system based on independent metering control is proposed combined with the independent metering control *** configuration principle of the system is given,the mathematical model of this system is established,and the control strategy of the system under 4 different working quadrants is put ***,the control performance and energy saving characteristics of the system are *** test results show that the switching of high and low pressure power supply has a certain effect on the response of step position and ramp position under impedance working *** displacement curves show slow climbing or abrupt change of ramp position,and the position accuracy is less than 1 *** multi-level pressure switching control system based on independent metering control can recover and store energy under the transcendence working *** control accuracy is about 1 mm,and the energy recovery rate is about 70%~80%.

关键词： multi-level pressure independent metering control displacement control energy saving hydraulic switching system