GMRTHI observations of the Eridanus group of galaxies     

A. Omar  K. S. Dwarakanath 《Journal of Astrophysics and Astronomy》2005,26(1):1-70

The GMRTHI 21 cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ≈ 23 Mpc, is a loose group of ≈200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ≈240 km s⁻¹. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + S0) and 70% (Sp + Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ≈ 200 h. HI emission was detected from 31 galaxies. The channel rms of ≈ 1 mJy beam⁻¹ was achieved for most of the image-cubes made with 4 h of data. The corresponding HI column density sensitivity (3σ) is ≈ 1 × 10²⁰ cm⁻² for a velocity-width of ≈ 13.4 km s⁻¹. The 3σ detection limit of HI mass is ≈ 1.2 X 10⁷ Mpd for a line-width of 50 km s⁻¹. Total HI images, HI velocity fields, global HI line profiles, HI mass surface densities, HI disk parameters and HI rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. These data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and HI lopsidedness in galaxies.  相似文献   

新世纪我国地质钻探技术发展的思考          下载免费PDF全文

曾南中  李振潜 《探矿工程》1995,(4):26-27

探讨了新世纪我国地质钻探技术的发展，论述了综合钻探技术是我国未来地质钻探技术的发展方向，分析了发展综合钻探技术的必要性及有利条件，并提出了前期应做的准备工作。  相似文献   

徐深21-平1井轨迹控制技术          下载免费PDF全文

孟祥波  陈春雷  孙长青 《探矿工程》2014,41(1):30-32

徐深21-平1井完钻井深4955 m。在火山岩储层中横向穿行905 m,井眼轨迹控制精度要求高,并在登二泥岩段岩石可钻性达8级的情况下裸眼侧钻成功,为后续施工奠定了基础。简述了井身结构及轨迹剖面设计,分析了井眼轨迹控制难点,详细介绍了增斜段、侧钻段、水平段井眼轨迹控制情况。该井的成功钻探,为该区块水平井施工积累了宝贵经验。  相似文献   

The Middle Triassic (Anisian) Otter Sandstone biota (Devon,UK): review,recent discoveries and ways ahead     

Robert A. Coram  Jonathan D. Radley  Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(3-4):294-306

The Middle Triassic (Anisian) Otter Sandstone was laid down mostly by braided rivers in a desert environment and is now well exposed along the south-east Devon coast in south-west England, part of the ‘Jurassic Coast’ World Heritage Site. It yields uncommon and generally fragmentary fossils, principally of vertebrates, including fish, temnospondyl amphibians and reptiles such as rhynchosaurs, predatory archosaurs, and small superficially lizard-like forms. These provide important information about a freshwater and terrestrial ecosystem that marks recovery from the end-Permian mass extinction, but pre-dated the appearance of dinosaurs and mammals. The constantly eroding Otter Sandstone exposures continue to reveal new taxa (for example, freshwater sharks). Furthermore, microvertebrate material obtained by sieving bone-bearing levels has the potential to further expand the faunal list. Newly discovered associated and articulated vertebrate remains, including small tetrapods, improve knowledge of whole-body anatomy and facilitate systematic work. Invertebrate burrows and reptile footprints provide information on ecological interactions and detailed bed-by-bed collecting casts light on taphonomic processes and faunal changes over time.  相似文献   

21 世纪末珠江口深圳最高潮位重现期值预估     

聂宇华  汤超莲  程泽梅 《热带地理》2016,36(6):901-905

采用 P-III 适线拟合法分析赤湾验潮站建站以来的潮位资料,得出该站 1965―2014 年最高潮位的重现期值：其中 100 a 一遇最高潮位为 2.31 m,50 a 一遇最高潮位为 2.18 m。通过插值法分析 1965―2011 年赤湾站与北角/鰂鱼涌站的年最高潮位,得出两者存在显著相关关系,并据此后报出赤湾站近百年来 2 次最高潮位为 1962 年2.7 m 和 1937 年 2.34 m。。根据 IPCC AR5 中的 RCP2.6 方案,预估了 21 世纪末（2081―2100 年）赤湾最高潮位的重现期：100 a 最高潮位在全球海平面上升 0.24 m 的情况下为 2.55 m,在全球海平面上升 0.40 m 的情况下为 2.71m。并讨论了围海造地导致伶仃洋潮位上升率降低以及 0814 号台风“黑格比”对赤湾站增水的影响：赤湾北面西乡沿海地势特别低,当潮位≥1.40 m（珠基起算）时,就会发生海水倒灌现象。也就是说,未来海平面的上升将加大该区海水倒灌频率。通过分析台风过境时该站的潮位观测资料,得出 0814 号台风“黑格比”经过珠江口时赤湾站的最高潮位为增水 1.46 m。最后,重新修订了赤湾站最高潮位的重现期值,这不但能够提高该区域防台水位设计的准确性,还能为该海域的风暴潮预警预报提供参考依据。  相似文献   

渤海海域旅大21-A构造沙四段储集层特征及控制因素     

刘志刚  杜晓峰  王清斌  王军  王晓刚  郭涛 《海洋地质译丛》2012,(2):26-29,89

渤海海域旅大21-A构造在3600m以下的沙四段中发现了很好的油气显示,并且测试成功。沙四段在该构造是个新的油气勘探层系,具有很好的勘探前景。为了更好地研究该构造储集层情况,通过对该构造沙四段岩心、壁心资料,运用常规、铸体薄片鉴定和扫描电镜等化验分析资料,对该构造沙四段储集层基本特征进行了系统分析,认为该构造岩性主要以长石岩屑砂岩为主,岩屑长石砂岩次之,孔隙质量为中等一好,渗透率为特低渗～中渗,储集层物性中等。确定了影响储集层物性的主要因素为沉积作用、成岩作用和构造作用,三者综合影响着储集层的物性变化。  相似文献   

Evaluation of two spectral wave models for wave hindcasting in the Mackenzie Delta     

《Applied Ocean Research》2017

Climate change, reduced sea ice and increased ice-free waters over extended areas for longer summer periods potentially lead to increased wave energy in the Beaufort Sea (Wang et al., 2015; Khon et al., 2014) [1], [2], which is a major concern for coastal and offshore engineering activities. We compare two spectral wave models SWAN (Simulating WAves Nearshore) and MIKE 21 SW (hereafter MIKE21) in simulations of storm-generated waves in the Mackenzie Delta region of the southern Beaufort Sea. SWAN model simulations are performed using two nested grids system, whereas MIKE21 uses an unstructured grid system. Forcing fields are defined by hourly hindcast winds. Moving ice edge boundaries are incorporated during storm simulations. Modelled wave spectra from four storms are shown to compare well with field observations. Two established whitecapping formulations in SWAN are investigated: one dependent on mean spectral wave steepness, and the other on local spectral steepness. For the Beaufort Sea study area, we suggest that SWAN wave simulations using the latter local spectral steepness formulation are better than those using the former mean spectral steepness formulation. MIKE21 simulations also tend to agree with SWAN results using the latter whitecapping formulation.  相似文献   

Harnessing the wind: A case study of applying Flettner rotor technology to achieve fuel and cost savings for Fiji's domestic shipping industry     

《Marine Policy》2017

For over 5000 years, humans have successfully harnessed the power of wind to transport people and goods across the world's oceans. This research expands on previous studies of the unique Flettner rotor propulsion system and the demonstrable success in reducing fuel consumption and carbon dioxide (CO₂) emissions. Recent examples such as Enercon's E-ship 1 have proven seaworthy and economically viable along major shipping routes. The remote Pacific island countries (PICS), however, have the unique characteristics of retaining a remarkable seafaring heritage while remaining on the periphery of global commerce. With data obtained from a field study of Fiji's domestic shipping, this research analyzes the potential for implementing Flettner rotor systems to achieve more economically viable alternatives to the current situation. The findings show that with an incremental approach and the addition of a government fuel savings incentive, the Government Shipping Franchise Scheme (GSFS) subsidies could be significantly lowered for Fiji's ten uneconomical shipping routes. Four scenarios of 5%, 10%, 15%, and 25% fuel savings contrast the baseline data on one extreme with a zero-emissions scenario on the other. The most likely fuel savings scenario of between 10% and 15% results in a 20-year government savings of between 348,042 and 522,063 U.S. dollars and a 20-year cumulative reduction in CO₂ emissions of between 2931 and 4396 t. The paper concludes that Flettner rotors show promising results in reducing fuel consumption and CO₂ emissions and recommends future studies in collaboration with the Fiji government to develop practical strategies of implementation.  相似文献   

21世纪中国东北地区气候变化预估   总被引：14，自引：3，他引：11       下载免费PDF全文

赵宗慈  罗勇 《气象与环境学报》2007,23(3):1-4

利用各国政府间气候变化专门委员会(IPCC)第4次科学评估报告中全球气候系统模式组考虑人类排放情景的计算结果,计算与分析了多个气候模式对21世纪中国东北地区气候变化的集成预估结果。多模式集成预估结果表明:到21世纪后期,由于人类排放增加的影响,中国东北地区气温将可能较目前变暖3.0℃或以上,降水将可能增加。需要注意这种气候变化对中国东北地区社会经济的长远影响。  相似文献   

山东威海滨海新城北部海域潮流数值模拟研究          下载免费PDF全文

王玉莲  张坤  王振兴  高光  王嫚 《山东国土资源》2023,39(3)

山东省威海市滨海新城作为威海市的新行政中心，是威海市着力打造的宜居、宜业、宜游、宜学的现代化卓越新城。本文采用MIKE21FM平面二维数值模型研究威海市滨海新城北部海域的潮流场运动，并以分层流速流向实测资料对模型进行验证。结果表明，研究区潮流场流速和流向数值模拟结果与实测资料变化基本一致。  相似文献