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A limit equilibrium fracture zone model to investigate seismicity in coal mines

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International Journal of Mining Science and Technology 2018年第5期28卷 745-753页

作者： Daniel Malan John Napier department of Mining engineering Faculty of Engineering Built Environment and IT University of Pretoria

This paper explores possible synergies between techniques used to minimise seismicity in deep South African gold mines and their applicability to control coal bumps. The paper gives a summary of the techniques used in the deep gold mines and a critical appraisal if these are useful in coal mines. The techniques typically include control of mining rate, preconditioning, optimisation of extraction sequences and centralised blasting. Of particular interest to the coal bump problem is an experimental limit equilibrium fracture zone model implemented in a displacement discontinuity code. This was recently developed for the gold mines to enable the interactive analysis of complex tabular mine layout extraction sequences. The model specifically accommodates energy dissipation computations in the developing fracture zone near the edges of these excavations. This allows the released energy to be used as a surrogate measure of ongoing seismic activity and addresses a number of the weaknesses in the traditional usage of this quantity as a criterion for the design of seismically active layouts. This paper investigates the application of the model to a hypothetical coal longwall layout and the specific problem of coal bumps.

关键词： Coal bumps Limit equilibrium model Mining rate Seismicity

The failure propagation of weakly stable sediment:A reason for the formation of high-velocity turbidity currents in submarine canyons

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Journal of Oceanology and Limnology 2023年第1期41卷 100-117页

作者： Yupeng REN Yi ZHANG Guohui XU Xingbei XU Houjie WANG Zhiyuan CHEN Shandong Provincial Key Laboratory of marine environment and Geological engineering Qingdao 266100China Shandong Provincial Key Laboratory of marine environment and Geological engineering Ocean University of ChinaQingdao 266100China Key Laboratory of marine environment and Ecology Ocean University of ChinaMinistry of EducationQingdao 266100China

The long-distance movement of turbidity currents in submarine canyons can transport large amounts of sediment to deep-sea *** studies show obvious differences in the turbidity current velocities derived from the multiple cables damage events ranging from 5.9 to 28.0 m/s and those of field observations between 0.15 and 7.2 m/***,questions remain regarding whether a turbid fluid in an undersea environment can flow through a submarine canyon for a long distance at a high speed.A new model based on weakly stable sediment is proposed(proposed failure propagation model for weakly stable sediments,WS S-PFP model for short)to explain the high-speed and long-range motion of turbidity currents in submarine canyons through the combination of laboratory tests and numerical *** model is based on two mechanisms:1)the original turbidity current triggers the destabilization of the weakly stable sediment bed and promotes the destabilization and transport of the soft sediment in the downstream direction and 2)the excitation wave that forms when the original turbidity current moves into the canyon leads to the destabilization and transport of the weakly stable sediment in the downstream *** proposed model will provide dynamic process interpretation for the study of deep-sea deposition,pollutant transport,and optical cable damage.

关键词： turbidity current excitation wave dense basal layer velocity WSS-PFP model

An experimental study on thermal characteristics of nanofluid with graphene and multi-wall carbon nanotubes

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Journal of Central South University 2015年第8期22卷 3202-3210页

作者： A.K.M Mahmudul Haque Sunghyun Kwon Junhyo Kim Jungpil Noh Sunchul Huh Hanshik Chung Hyomin Jeong department of Ocean System engineering Gyeongsang National University department of marine environmental engineering Gyeongsang National University department of marine engineering Mokpo National Maritime University department of Energy and Mechanical engineering Gyeongsang National UniversityInstitute of Marine Industry

High-thermal conductivity enhancement of nanofluid is one of the promising topics of the nanoscience research field. This work reports the experimental study on the preparation of graphene(GN) and multi-walled carbon nanotubes(MWCNTs) based nanofluids with the assistance of sodium dodecyl benzene sulfonate(SDBS) and sodium dodecyl sulfate(SDS) surfactants, and their thermal behaviors. The present work suggests not a solution, but a solution approach and deduces a new conclusion by trying to resolve the agglomeration problem and improve the dispersibility of nanoparticles in the base fluid. The analysis results of FESEM, thermal conductivity, diffusivity, effusivity and heat transfer coefficient enhancement ratio of nanofluid with surfactants SDS and SDBS expose strong evidence of the dispersing effect of surfactant on the making of nanofluid.

关键词： graphene carbon nanotube surfactant dispersibility thermal conductivity

Characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater effluent

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Journal of environmental Sciences 2010年第6期22卷 940-945页

作者： Soyoung Lee Marla C.Maniquiz Lee-Hyung Kim department of Civil & environment engineering Kongju National University

Constructed wetland （CW） is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary effluent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery wastewater effluent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the CW were non-apatite phosphorus （59%） and residual phosphorus （32%） suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW system and design.

关键词： constructed free water surface wetland piggery wastewater phosphorus type secondary wastewater effluent sediment

An implementation strategy to quantify the marine microbial carbon pump and its sensitivity to global change

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National Science Review 2018年第4期5卷 474-480页

作者： Carol Robinson Douglas Wallace Jung-Ho Hyun Luca Polimene Ronald Benner Yao Zhang Ruanhong Cai Rui Zhang Nianzhi Jiao University of East Anglia School of Environmental Sciences Oceanography department Dalhousie University Hanyang University Department of Marine Science and Convergence Engineering Plymouth marine Laboratory University of South Carolina Department of Biological Sciences and School of the EarthOcean and Environment State Key Laboratory of marine environmental Science and Institute of marine Microbes and Ecospheres

INTRODUCTION The persistence of the vast pool of recalcitrant dissolved organic carbon(RDOC)in the deep ocean is fundamental to both global carbon cycling and global ***,quantitative understanding of the mechanisms that produce and utilize RDOC is still in its *** from a conceptual framework to quantitative understanding in marine carbon cycling can take the international research community several decades—precious time

关键词： MCP An implementation strategy to quantify the marine microbial carbon pump and its sensitivity to global change

Characterization and analysis of ribosomal proteins in two marine calanoid copepods

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Chinese Journal of Oceanology and Limnology 2016年第6期34卷 1258-1268页

作者：杨菲菲徐东会庄昀筠黄有松衣晓燕陈洪举刘光兴张寰 Key Laboratory of marine environment and Ecology(Ocean University of China) Ministry of Education College of environmental Science and engineering Ocean University of China department of marine Sciences University of Connecticut

Copepods are among the most abundant and successful metazoans in the marine ecosystem. However, genomic resources related to fundamental cellular processes are still limited in this particular group of crustaceans. Ribosomal proteins are the building blocks of ribosomes, the primary site for protein synthesis. In this study, we characterized and analyzed the c DNAs of cytoplasmic ribosomal proteins(c RPs) of two calanoid copepods, P seudodiaptomus poplesia and A cartia pacifi ca. We obtained 79 c RP c DNAs from P. poplesia and 67 from A. pacifi ca by c DNA library construction/sequencing and rapid amplifi cation of c DNA ends. Analysis of the nucleic acid composition showed that the copepod c RP-encoding genes had higher GC content in the protein-coding regions(CDSs) than in the untranslated regions(UTRs), and single nucleotide repeats(>3 repeats) were common, with "A" repeats being the most frequent, especially in the CDSs. The 3′-UTRs of the c RP genes were signifi cantly longer than the 5′-UTRs. Codon usage analysis showed that the third positions of the codons were dominated by C or G. The deduced amino acid sequences of the c RPs contained high proportions of positively charged residues and had high p I values. This is the fi rst report of a complete set of c RP-encoding genes from copepods. Our results shed light on the characteristics of c RPs in copepods, and provide fundamental data for further studies of protein synthesis in copepods. The copepod c RP information revealed in this study indicates that additional comparisons and analysis should be performed on different taxonomic categories such as orders and families.

关键词： amino acid composition codon usage copepod nucleotide composition ribosomal protein

Primers to block the amplification of symbiotic apostome ciliate 18S rRNA gene in a PCR-based copepod diet study

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Chinese Journal of Oceanology and Limnology 2014年第3期32卷 515-521页

作者：衣晓燕张寰刘光兴 College of environmental Science and engineering Ocean University of China department of marine Sciences Connecticut University Key Laboratory of marine environment and Ecology ( Ocean University of China ) Ministry of Education

Pelagic copepods play an important role in the marine food web. However, a full understanding of the ecological status of this zooplankton group depends on the careful study of their natural diets. In previous PCR-based copepod diet studies, we found many apostome ciliates that live symbiotically under the exoskeleton of the copepods, and their sequences were often over-represented in the 18S rRNA gene （18S rDNA） libraries. As a first step to address this issue, we designed three apostome ciliate 18S rDNA blocking primers, and tested their blocking efficiency against apostome ciliate 18S rDNA under various PCR conditions. Using a semi-quantitative PCR method, we optimized the conditions to efficiently amplify the 18S rDNA of the prey while simultaneously excluding the symbiotic apostome ciliates. This technique will facilitate PCR-based diet studies of copepods and other zooplankton in their natural environments.

关键词： copepod 18S rDNA apostome ciliate blocking primer PCR

WAKE SHIELDING EFFECTS OF THREE CYLINDERS IN CURRENTS

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Journal of Hydrodynamics 2004年第3期16卷 241-247页

作者： BOLSTAD Jarle Joint department of Naval Architecture and marine engineering

A large amount of experimental work has been carried out in the past tounderstand mean and fluctuating forces on a single circular cylinder in cross flows. In comparisonsubstantially less work can be found on the interference between multiple cylinders and the numberof publications a-vailable becomes drastically smaller as the number of cylinders involvedincreases. The current experimental work systematically examines the wake shielding effects of threecylinders in a towing tank. Though staggered, the three cylinders are arranged mainly along theflow direction with the downstream cylinders situating in the wakes of the upstream cylinders. Thetests are mainly carried out in the sub-critical Reynolds number regime with the upper end close tothe critical Reynolds number regime. Significant drag reduction on downstream cylinders isidentified.

关键词： wake shielding three cylinders interaction marine riser

Sources and distribution of sedimentary organic matter along the northern Bering and Chukchi Seas

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Journal of environmental Sciences 2017年第2期29卷 66-75页

作者： Fanglu Xu Haiyan Jin Zhongqiang Ji Jianfang Chen Pei Sun Loh Institute of marine Chemistry and environment Department of Marine Sciences Ocean College Zhejiang University Laboratory of marine Ecosystem and Biogeochemistry Second Institute of OceanographyThe State Oceanic Administration

In this study, lignin-derived phenols were used to determine the sources and distribution of sedimentary organic matter along the northern Bering Sea and Chukchi Sea of the Arctic Ocean. The lignin parameter syringyl/vanillyl（S/V） and cinnamyl/vanillyl（C/V） ratios are used to indicate vegetation sources; and the ratios of vanillic acid/vanillin,（Ad/Al）v and syringic acid/syringaldehyde,（Ad/Al）s are used as indicators of lignin diagenesis. Results showed the predominance of woody gymnosperm signal at the easternmost location in the northern Bering Sea, a mixture of refractory non-woody angiosperm and fresher gymnosperm tissues in the Chukchi Sea, and signal of fresher woody gymnosperm tissues in the northernmost locations in the Chukchi Sea. The lignin materials showed gradual increase in decomposition stage during transport along the northern Bering Sea. Hydrodynamic sorting process, which is the retention of coarser materials nearshore and transportation of finer particles farther offshore, most probably occurred along the east coast of the northern Bering Sea. In Chukchi Sea, the non-woody angiosperm tissues could have originated from the Canadian Arctic and gymnosperm tissues could be from the Russian Arctic side. The fresher materials in the northernmost Chukchi Sea could have been transported here via the ice-rafting *** of fresh lignin materials and the occurrence of lignin decomposition mean that this region could be sensitive to the impact of climate change.

关键词： Lignin-derived phenols Northern Bering Sea Chukchi Sea