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silicification in Mississippian Lodgepole Formation,Northeastern Flank of Williston Basin,Manitoba,Canada

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Journal of Earth science 2012年第1期23卷 1-18页

作者： Harvey R young Moe Kuroda Department of Geology Brandon University

Five types of replacement silica are recognized in the Lower Mississippian Virden Member carbonates on the northeastern flank of Williston basin： microcrystalline quartz, chalcedonic quartz, anhedral megaquartz, euhedral megaquartz, and stringy megaquartz. silica tends to replace various bioclasts, and all except the stringy megaquartz also occur as non-replacive void-filling cement or as silica forming chert nodules and silicified limestone. Although crinoids, brachiopods, corals, bryozoans, molluscs, trilobites, forams, and ostracodes are present in the sediments studied, only the first three show evidence of silicification. Crinoids are commonly replaced by microcrystalline quartz whereas brachiopods typically by spherules of length slow chalcedony. Coalesced spherules, often in concentric rings （beekite rings）, may form sheet-like masses on the surface of corals and brachiopods. Although bryozoans are common in the Virden Member, none showed any evidence of silicification. The difference in the susceptibility to silicification may be related to the shell microstructure, biological group, size of organism, skeletal mineralogy, and organic content of the bioclasts. Biogenic silica derived from the dissolution of siliceous sponge spicules is considered to be the most likely silica source for silicification. Most silica is believed to be released during early diagenesis before the sediments were deeply buried. The Virden Member carbonate may have experienced two episodes of replacement, the first affecting the bioclasts, the second producing silicified limestone and chert nodules.

关键词： silicification Williston basin Lodgepole Formation Virden Member Mississippian carbonate.

Phosphorus fractionation and release characteristics of sediment in the saemangeum Reservoir for seasonal change

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International Journal of sediment Research 2018年第3期33卷 250-261页

作者： Dong-Heui Kwak young-Tae Jeon young Duck Hur Jeongeup Industry-Academic Cooperation support Center Chonbuk National University Jeollabuk-do Provincial Covernment Department of Environmental Engineering Chonbuk National University

Periodical algal blooms result in deposition and release of phosphorus(P) from the sediment into the water. Therefore, during seasonal changes when algal particles begin to settle to the bottom, understanding the behavior and distribution characteristics of the P in sediment is the most important key to manage the water quality of the saemangeum Reservoir. In this study, the variation of water quality and sediment composition including chlorophyll-a(Chl-a) and P was investigated to determine the interaction between water and sediment. The study focused primarily on algal particle sedimentation that affects the P release and mineralization of sediment. The Chl-a concentration in water showed a sharp decline in October when the algae began to die in the fall, and afterward the concentration of chemical oxygen demand(COD) and total P(TP) in the sediment increased due to the sedimentation of decaying algal particles in *** the same period of time, the readily bio-available P(RAP) in the sediment showed a drastic increase in the upper region where the Chl-a concentration of water was high. In sequence, the high RAP zone shifted from the upper region to the lower region in the early winter. The RAP shift was considered to be derived from the physical flow of the overlying water from which the decomposing algae settled on the surface of the sediment. The saemangeum Reservoir was constructed recently; therefore, all the types of inorganic P fractions except soluble reactive phosphorus(sRP) that exist on the bottom surface of the lake and the marsh’s sediment layer were not sufficient to significantly influence the overlying water. On the other hand, the released P from the algae was distinct and sensitive to the seasonal change. In conclusion,the algal particle sedimentation was important to control eutrophication rather than P release from the mineralized inorganic P of the sediment surface layer in the seamangeum Reservoir.

关键词： Algal bloom Fractionation Phosphorus Water management Release sediment

Evidence of specific MJO Phase Occurrence with summertime California Central Valley Extreme Hot Weather

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Advances in Atmospheric sciences 2019年第6期36卷 589-602页

作者： Yun-young LEE Richard GROTJAHN Asia-Pacific Economic Cooperation Climate Center Department of Land Air and Water Resources University of California

This study examines associations between California Central Valley(CCV) heat waves and the Madden Julian Oscillation(MJO). These heat waves have major economic impact. Our prior work showed that CCV heat waves are frequently preceded by convection over the tropical Indian and eastern Pacific oceans, in patterns identifiable with MJO phases. The main analysis method is lagged composites(formed after each MJO phase pair) of CCV synoptic station temperature, outgoing longwave radiation(OLR), and velocity potential(VP). Over the CCV, positive temperature anomalies occur only after the Indian Ocean(phases 2-3) or eastern Pacific Ocean(phases 8-1) convection(implied by OLR and VP fields). The largest fractions of CCV hot days occur in the two weeks after onset of those two phase pairs. OLR and VP composites have significant subsidence and convergence above divergence over the CCV during heat waves, and these structures are each part of larger patterns having significant areas over the Indian and Pacific Oceans. Prior studies showed that CCV heat waves can be roughly grouped into two clusters: Cluster 2 is preceded by a heat wave over northwestern North America, while Cluster 1 is not. OLR and VP composite analyses are applied separately to these two clusters. However, for Cluster 2, the subsidence and VP over the CCV are not significant, and the large-scale VP pattern has low correlation with the MJO lagged composite field. Therefore, the association between the MJO convection and subsequent CCV heat wave is more evident in Cluster 1 than Cluster 2.

关键词： MJO heat wave large-scale meteorological pattern extratropical response tropical convection

simulation of wind-induced near-inertial oscillations in a mixed layer near the east coast of Korea in the East/Japan sea

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Acta Oceanologica sinica 2013年第9期32卷 11-20页

作者： NAM sungHyun PARK young-Gyu Naval systems Development Center Agency for Defense Development Ocean Circulation and Climate Research Division Korea Institute of Ocean Science and Technology

Using a simple damped slab model, it was possible to show that a local wind induced 88% （15 of 17） of the near-inertial oscillations （NIO） observed in the mixed layer near the east coast of Korea from 1999 to 2004. The model, however, overestimated the energy level in about two-thirds of the simulated cases, because the slab model was forced with winds whose characteristic period was shorter than the damping time scale of the model at 1.5 d. At the observation site, due to typhoons and orographic effects, high-frequency wind forcing is quite common, as is the overestimation of the energy level in the slab model results. In short, a simple slab model with a damping time-scale of about 1.5 d would be enough to show that the local wind was the main energy source of the near-inertial energy in this area, but the model could not be used to accurately estimate the amount of the work done by the wind to the mixed layer.

关键词： near-inertial oscillations near-inertial waves slab model high-frequency wind forcing eastcoast of Korea

Cardiovascular Care for Older Adults Aortic valve disease in the older adult

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Journal of Geriatric Cardiology 2016年第12期13卷 941-944页

作者： neal Bhatia sukhdeep s Basra Adam H skolnick Nanette K Wenger Emory University school of Medicine Atlanta GA USA The Heart Hospital Baylor Piano Dallas TX USA Leon H Charney Division of Cardiology New York University Langone Medical Center NY USA

As the population continues to age, aortic stenosis re- mains as the most prevalent valvular disease in Western countries. The number of elderly patients with aortic ste- nosis continues to pose both a diagnostic and therapeutic challenge. Despite new advances such as transcatheter aortic valvular replacement （TAVR）, there is still much pa- tient-provider decision making that needs to take place giv- en the comorbidities and complex goals of care in an elderly patient population.

关键词： Aortic stenosis The elderly Valve disease

Effect of thixoextrusion parameters on mechanical properties of 7003 Aluminum wrought alloy

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Rare Metals 2006年第z2期25卷 124-128页

作者： YOON young-Ok JANG Dong-In JO Hyung-Ho KIM young-Jig KIM shae K Department of Advanced Material Engineering Sungkyunkwan University 300 Chunchun-dong Jangan-gu Suwon Gyunggi-do 440-746 KoreaAdvanced Material Center Korea Institute of Industrial Technology 7-47 Songdo-dong Yeonsu-gu Incheon 406-840 Korea Advanced Material Center Korea Institute of Industrial Technology 7-47 Songdo-dong Yeonsu-gu Incheon 406-840 Korea Department of Advanced Material Engineering Sungkyunkwan University 300 Chunchun-dong Jangan-gu Suwon Gyunggi-do 440-746 Korea

The processing of high strength Al wrought alloys does lead either to restrictions for geometrical complexity or to high production costs due to low productivity and multiple-step processes. Thixoextrusion process to overcome these difficulties has been under investigation. In the present study, the effect of thixoextrusion parameters was investigated on mechanical properties of 7003 Al wrought alloy. The maximum extrusion pressure of the thixoextrusion process is three times lower than that of the hot extrusion process. The elongated grains which have the axisymmetry with extrusion direction are generally observed during hot extrusion process, while the microstructures of the thixoextruded are isotropic. The tensile and yield strengthes of the thixoextruded bar are lower than those of the hot extruded bar, while the elongation value of the thixoextruded bar is higher than that of the hot extruded bar.

关键词： thixoextrusion isotropy 7003 Al wrought alloy

Hydro-mechanical behavior of an argillaceous limestone considered as a potential host formation for radioactive waste disposal

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第6期10卷 1063-1081页

作者： T.s.Nguyen Zhenze Li Grant su M.H.B.Nasseri R.P.young Canadian Nuclear safety Commission OttawaCanada Department of Civil Engineering University of TorontoTorontoCanada

The Canadian Nuclear safety Commission(CNsC), Canada’s nuclear regulator, conducts regulatory research in order to develop independent knowledge on safety aspects related to the deep geological disposal of radioactive wastes. In Canada, the Cobourg limestone of the Michigan Basin is currently considered as a potential host formation for geological disposal. The understanding of the hydromechanical behavior of such a host rock is one of the essential requirements for the assessment of its performance as a barrier against radionuclide migration. The excavation of galleries and shafts of a deep geological repository(DGR) can induce damage to the surrounding rock. The excavation damaged zone(EDZ) has higher permeability and reduced strength compared to the undisturbed rock and those factors must be considered in the design and safety assessment of the DGR. The extent and characteristics of the EDZ depend on the size of the opening, the rock type and its properties, and the in situ stresses, among other factors. In addition, the extent and characteristics of the EDZ can change with time due to rock strength degradation, evolution of fractures within the EDZ, and the redistribution of pore pressure around the excavation. In this research project initiated by the CNsC, the authors conducted experimental and theoretical research in order to assess the hydro-mechanical behavior of the Cobourg limestone under undamaged and damaged conditions, both in the short and long terms. The short-term behavior was investigated by a program of triaxial tests with the measurement of permeability evolution on specimens of Cobourg limestone. The authors formulate a coupled hydro-mechanical model to simulate the stress-strain response and evolution of the permeability during those triaxial tests. Using creep and relaxation data from a similar limestone, the model was extended to include its long-term strength degradation. The model successfully simulated both the short-and long-term hydro-me

关键词： Hydro-mechanical behavior Excavation damage Deep geological repository(DGR) Limestone Poro-elasto-plasticity

Realization of Numbers As the Degrees of Maps between Manifolds

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Acta Mathematica sinica,English series 2010年第8期26卷 1413-1424页

作者： young Min LEE Fei XU Department of Mathematics Seoul National University Seoul 151747 Republic of Korea school of Mathematics Capital Normal University Beijing 100048 P. R. China

We determine the set of degrees between some classes of oriented closed （n - 1）-connected 2n-manifolds by using the arithmetic theory of quadratic forms.

关键词： Oriented closed manifold degree of a map integral quadratic form

Investigation of factors influencing roof stability at a Western *** coal mine

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International Journal of Mining science and Technology 2019年第1期29卷 139-143页

作者： Meriel young Gabriel Walton Elizabeth Holley Department.Geology&Geol.Engineering Colorado School of Mines Department Mining Engineering Colorado School of Mines

The coal mine roof rating(CMRR) was developed to bridge the gap between geological variation in underground coal mines and engineering design. The CMRR accounts for the compressive strength of the immediate roof, the shear strength and intensity of any discontinuities present, and the moisture sensitivity of the immediate roof. The CMRR has been widely used and validated in Eastern Us coal mines, but it has seen limited application in the Western Us. This study focuses on roof behavior at a Western coal mine(Mine A). Mine A shows significant lateral geological variation, along with localized faulting and a laterally extensive sandstone channel network. The CMRR is not used to predict roof instability at the mine. It is, therefore, hypothesized that there are other factors that are correlated with roof instability in underground coal mines that could potentially also be considered in conjunction with the *** hypothesis was tested by collecting 30 CMRR measurements at Mine A. At each measurement location, a binary record of the roof condition(stable or unstable) was made, and other parameters such as depth of cover, presence of faulting, and sandstone channels were also recorded. ANOVA tests showed that the CMRR values and the roof conditions were not strongly correlated, indicating that the CMRR input criteria are not fully predictive of roof stability at this mine. The CMRR values showed statistically significant correlations(p less than 0.05) with faulting as well as with location at an intersection. For areas that had previously experienced roof fall but were currently stable, faulting was correlated with roof condition(p less than 0.05) only when the condition was classified as unstable.

关键词： Coal mine roof stability CMRR Western U.s.coal Case study