Flow Characteristics of Microbubble Suspensions in Porous Media as an Oxygen Carrier     

Yong Ju Choi  Joo Young Park  Young‐Jin Kim  Kyoungphile Nam 《洁净——土壤、空气、水》2008,36(1):59-65

Microbubble suspensions were generated as an oxygen carrier for aerobic biodegradation, and their flow characteristics in porous media were investigated. Commercial surfactants including sodium dodecyl sulfate (SDS), and dodecylethyldimethylammonium bromide (DEDAB), saponin (a natural surfactant), and collagen (a protein hydrolysate) were examined as base materials for generating microbubble suspensions. Among them, 2×CMC (critical micellar concentration) of SDS, DEDAB, and saponin developed microbubble suspensions with the highest gas hold‐up and half‐drainage time. Visualization of the flow patterns in sand showed that the microbubble suspensions were separated into a liquid and gas phase directly after injection, showing much faster movement of liquid phase flow. The gas front of the microbubble suspensions flowed in a plug‐flow manner, particularly in cases of SDS and DEDAB. The experimental results from both homogeneous and heterogeneous cells confirmed that the microbubble flow could overcome the heterogeneity in porous media. However, the plug‐flow characteristics and flow propagation of the microbubble suspensions to the low‐permeability zone was accompanied by a large pressure drop, which needs to be considered for future field application.  相似文献   

Reducing the effects of vegetation phenology on change detection in tropical seasonal biomes     

Eduarda Martiniano de Oliveira Silveira  Fernando Del Bon Espírito-Santo  Fausto Weimar Acerbi-Júnior  Lênio Soares Galvão  Kieran Daniel Withey  George Alan Blackburn 《地理信息系统科学与遥感》2019,56(5):699-717

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Evaluating the potential of multi-view data extraction from small Unmanned Aerial Systems (UASs) for object-based classification for Wetland land covers     

Tao Liu  Amr Abd-Elrahman  Bon Dewitt  Scot Smith  Jon Morton  Victor L. Wilhelm 《地理信息系统科学与遥感》2019,56(1):130-159

Unmanned Aerial Systems (UASs) have the potential to provide multi-view data, but the approaches used to extract the multi-view data from UAS and investigation of their use in image classification are currently unavailable in publications to our best knowledge. This study presents a method that combines collinearity equations and a two-phase optimization procedure to automatically project a point from real world coordinate system of an orthoimage to UAS image coordinate system (row and column numbers) to be used in multi-view data extraction. The results show average errors for the computed UAS column and row numbers were 1.6 and 1.8 pixels respectively evaluated with leave-one-out method. Based on this algorithm, it’s also for the first time that object-based multi-view data were extracted and presented, and the potential of using the multi-view data to aid Geographic Object-Based Image Analysis(GEOBIA) through bidirectional reflectance distribution function (BRDF) modelling was evaluated with two representatives of BRDFs, the Rahman-Pinty-Verstraete(RPV) and Ross-Thick-LiSparse (RTLS). Our results indicate the RPV model tends to overestimate the bidirectional reflectance for land cover types with high reflectance, while perform well for those with relatively low reflectance in our study area. To test the impact of using multi-view data on image classification, we extracted parameters from BRDF models and used these parameters as object features for object-based classification. The 10-fold cross validation results show that the 3-parameter RTLS significantly improved overall accuracy compared to the classifications relying only on the orthoimage features, while other BRDF models did not show significant improvements, raising the needs to develop new methods to better utilize the multi-view information in GEOIBA in the future.  相似文献   

Influence of environmental disturbances and reproductive strategy on genetic diversity and differentiation of Zostera marina populations on the southern coast of Korea     

Young Kyun Kim  Seung Hyeon Kim  Joo Mi Yi  Sang Rul Park  Kun‐Seop Lee 《Marine Ecology》2019,40(1)

The genetic diversity and differentiation of four Zostera marina populations along the southern coast of Korea were estimated using random amplified polymorphic DNA (RAPD) markers to determine the effects of natural and anthropogenic stresses and reproductive strategy on within‐population genetic diversity. The mean number of alleles and gene diversities, indicating population genetic diversity, was highest in the Z. marina population that was exposed to repeated environmental disturbances, and lowest in the most undisturbed population. The higher genetic diversity in the disturbed population was associated with a higher contribution of sexual reproduction to population persistence. This suggests that both the level of disturbances and the reproductive strategy for population persistence contributed significantly to population genetic diversity at the study sites. According to the analysis of molecular variance (AMOVA), 76% genetic variation was attributable to differences among individuals within populations. The observed genetic differentiation (F_ST = 0.241) among Z. marina populations at the study sites appeared to result from reduced meadow size, increased genetic drift, and a high incidence of asexual reproduction. Increased population genetic diversity can enhance resistance and resilience to environmental disturbances; thus, this investigation of seagrass population genetics provides valuable new insights for the conservation, management, and restoration of seagrass habitats.  相似文献   

Physiological Characteristics and Related Biochemical Parameters of Snow Algae from King George Island,Antarctica     

Bo?Kyung?Kim  HyoungMin?Joo  Boyeon?Lee  Dong-Hun?Lee  In-Young?Ahn  Sun-Yong?HaEmail author 《Ocean Science Journal》2018,53(4):621-630

Red and green snow caused by snow algal blooms is common on glaciers and snowfields worldwide. Reddish and greenish snow samples containing algae were collected at the vicinity of penguin rockeries on King George Island (62°13′S, 58°47′W, near the King Sejong Station), Antarctica in February 2017 to investigate their physiology. Eight pigments and six fatty acids were detected from the samples. No difference in pigment and fatty acid (FA) composition was found between reddish and greenish snow samples. In contrast, spectral profiling and mycosporine-like amino acids (MAAs) were different between reddish and greenish snow. Particularly in greenish snow, a high absorbance between 450–600 nm was observed. The average MAA concentration was 316.0 μg g^-1 in greenish snow, which was higher than that of reddish snow (278.2 μg g^-1). The MAA to Particulate organic carbon (POC) ratio (mg (g C)^-1) for reddish snow (6.2 mg (g C)^-1) was higher than that of greenish snow (2.6 mg (g C)^-1). These results suggest that reddish and greenish snow are considered to be the same species based on pigment and FA composition. Compared with photoprotective pigments, MAAs offer snow algae a more effective photoprotection strategy to promote tolerance of natural levels of ultraviolet radiation (UVR).  相似文献   

A new proposition for redating the Mithraic tauroctony scene     

E. Bon  M.M. &#x;irkovi&#x;  I. Milosavljevi&#x; 《Astronomische Nachrichten》2002,323(6):579-580

Assuming that the figures of the central icon of the Mithraic cult – the scene of tauroctony (bull slaying) – represent equatorial constellations at the time when the spring equinox was placed somewhere between Taurus and Aries, it is difficult to explain why some equatorial constellations (Orion and Libra) were not included in the Mithraic icons A simulation of the sky at the times in which the spring equinox was in the constellation of Taurus, only a small area of spring equinox positions permits to exclude these two constellations, with all other representations of equatorial constellations (Taurus, Canis Minor, Hydra, Crater, Corvus, Scorpio) included. These positions of the spring equinox occurred at the beginning of the age of Taurus, and included Gemini as an equatorial constellation. Two of the main figures in the Mithraic icons are two identical figures, usually represented on the each side of the bull, wearing phrygian caps and holding torches. Their names, Cautes and Cautopates, and their looks may indicate that they represent the constellation of Gemini. In that case the main icon of Mithraic religion could represent an event that happened around 4000 BC, when the spring equinox entered the constellation of Taurus. Also, this position of equator contains Perseus as an equatorial constellation. Ulansey suggested that the god Mithras is identified with the constellation Perseus. In that case, all figures in the main scene would be equatorial constellations.  相似文献   

Observational evidence for AGN feedback in early-type galaxies     

Kevin Schawinski  Daniel Thomas  Marc Sarzi  Claudia Maraston  Sugata Kaviraj  Seok-Joo Joo  Sukyoung K. Yi  Joseph Silk 《Monthly notices of the Royal Astronomical Society》2007,382(4):1415-1431

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Mechanism of skillful seasonal surface chlorophyll prediction over the southern Pacific using a global earth system model     

Ham  Yoo-Geun  Joo  Young-Sik  Park  Jong-Yeon 《Climate Dynamics》2021,56(1-2):45-64

Climate Dynamics - This study investigates the physical mechanism involved in an Earth system model (ESM)-based global marine biogeochemical prediction system providing successful forecasts of...  相似文献   

The Global/Regional Integrated Model system (GRIMs)   总被引：5，自引：0，他引：5  

Song-You Hong  Hoon Park  Hyeong-Bin Cheong  Jung-Eun Esther Kim  Myung-Seo Koo  Jihyeon Jang  Suryun Ham  Seung-On Hwang  Byoung-Kwon Park  Eun-Chul Chang  Haiqin Li 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(2):219-243

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Optimal tonal detectors based on the power spectrum     

Chun Ru Wan Joo Thiam Goh Hong Tat Chee 《Oceanic Engineering, IEEE Journal of》2000,25(4):540-552

The detection of tonals embedded in noise is an important sonar function and the traditional power spectrum analysis method has been widely used for this purpose. Wagstaff et al. (1997) proposed the WISPR (Wagstaff's Integration Silencing PRocessor) family processors, which perform a nonlinear integration or combination of the power spectrum observations. In this paper, we analyze the statistical property of the power spectrum observations and develop novel tonal detectors by optimally integrating the spectrum observations. The optimal detectors are derived by using the method of maximum likelihood hypothesis test. The results from simulations and real sea trial data have shown that the proposed detectors are promising in detecting tonals  相似文献