A deep learning approach for detecting candidates of supernova remnants     

Wei Liu  Cong Dai  Meng Zhu  Cong Dai  Bing-Yi Wang  Kang Wu  Xian-Chuan Yu  Wen-Wu Tian  Meng-Fei Zhang  Hong-Feng Wang 《天文和天体物理学研究(英文版)》2019,(3)

Detecting supernova remnant(SNR) candidates in the interstellar medium is a challenging task because SNRs have weak radio signals and irregular shapes. The use of a convolutional neural network is a deep learning method that can help us extract various features from images. To extract SNRs from astronomical images and estimate the positions of SNR candidates, we design the SNR-Net model composed of a training component and a detection component. In addition, transfer learning is used to initialize the network parameters, which improves the speed and accuracy of network training. We apply a T-T plot(of the different brightness temperatures of map pixels at two different frequencies) to calculate the spectral index of SNR candidates. To accelerate the scientific computing process, we take advantage of innovative hardware architecture, such as deep learning optimized graphics processing units, which increases the speed of computation by a factor of 5. A case study suggests that SNR-Net may be applicable to detecting extended sources in the images automatically.  相似文献   

印尼贯穿流源区马鲁古海和哈马黑拉海水团来源的气候态分析   总被引：3，自引：1，他引：2  

王露  谢玲玲  周磊  李强  石雨鑫  李明明 《海洋学报》2018,40(3):1-15

本文利用World Ocean Atlas 2013（WOA2013）气候态的温盐资料和the Simple Ocean Data Assimilation （SODA v3.3.1）流场数据,分析印尼贯穿流东部源区马鲁古海和哈马黑拉海的水团垂向分布特征及其来源,特别是次表层、中层及深层水的来源和路径。结果表明,气候态下,马鲁古海次表层的高温高盐水来自于北太平洋,与北太平洋热带水性质接近,哈马黑拉海次表层主要是来自南太平洋热带水;中层水以低温低盐为特征,马鲁古海的中层水来自南太平洋,受南极中层水控制,哈马黑拉海的中层水可能是从马鲁古海而来的南太平洋水;对于次表层和中层之间的过渡层,马鲁古海与哈马黑拉海的水源为南、北太平洋的混合水,且两个海域之间也存在着水团交换;在深层,马鲁古海的水源更倾向于班达海北部及塞兰海,而与太平洋水无关,哈马黑拉海由于地形阻挡也难以与太平洋直接发生水团交换。  相似文献   

化感物质抑制短裸甲藻的机理研究          下载免费PDF全文

韩锡锡  于庆云  鞠莲  李玲玲  谢冕 《海洋开发与管理》2018,35(5):71-76

文章通过研究邻苯二甲酸二丁酯(DBP)对短裸甲藻的活性氧自由基(ROS,主要为H_2O_2)水平、过氧化标志产物丙二醛(MDA)含量以及对细胞亚显微结构的影响,初步揭示DBP抑制短裸甲藻的机理,为沿海赤潮的控制和有效防治提供有力的支持。研究结果表明,DBP通过引起短裸甲藻细胞内活性氧自由基的过度积累而引起膜质过氧化,与不添加DBP的对照组相比,在低浓度DBP(0.1mg/L)的影响下,H_2O_2含量前48h变化比较平稳,48h以后逐渐下降。而在高浓度DBP(10mg/L)的影响下,H_2O_2含量变化波动明显,暴露72h后,H_2O_2含量达到248.24nmol·(10~7cells)~(-1),约是对照组的4.67倍。过氧化标志产物MDA在低浓度DBP(0.1mg/L)处理后暴露24h分别出现峰值0.23μmol·(10~9cells)~(-1)、0.28μmol·(10~9cells)~(-1),高浓度DBP(10 mg/L)处理MDA含量24h后持续上升,72h时高达0.351μmol·(10~9 cells)-1,约是对照组的2.32倍。同时DBP可以引起短裸甲藻细胞结构受损,表现在叶绿体、线粒体等细胞器变模糊,细胞空泡化,原生质膜皱缩,细胞脂质体(黑色颗粒)明显增多等,初步认为过氧化损伤为化感物质作用机理。  相似文献   

The Interactive Effects of Elevated CO<Subscript>2</Subscript> and Ammonium Enrichment on the Physiological Performances of <Emphasis Type="Italic">Saccharina japonica</Emphasis> (Laminariales,Phaeophyta)     

Jin Woo Kang  Ik Kyo Chung 《Ocean Science Journal》2018,53(3):487-497

Environmental challenges such as ocean acidification and eutrophication influence the physiology of kelp species. We investigated their interactive effects on Saccharina japonica (Laminariales, Phaeophyta) under two pH conditions [Low, 7.50; High (control), 8.10] and three NH ₄ ⁺ concentrations (Low, 4; Medium, 60; High, 120 μM). The degree of variation of pH values in the culture medium and inhibition rate of photosynthetic oxygen evolution by acetazolamide were affected by pH treatments. Relative growth rates, carbon, nitrogen, and the C:N ratio in tissue samples were influenced by higher concentrations of NH ₄ ⁺ . Rates of photosynthetic oxygen evolution were enhanced under elevated CO₂ or NH ₄ ⁺ conditions, independently, but these two factors did not show an interactive effect. However, rates of NH ₄ ⁺ uptake were influenced by the interactive effect of increased CO₂ under elevated NH ₄ ⁺ treatment. Although ocean acidification and eutrophication states had an impact on physiological performance, chlorophyll fluorescence was not affected by those conditions. Our results indicated that the physiological reactions by this alga were influenced to some extent by a rise in the levels of CO₂ and NH ₄ ⁺ . Therefore, we expect that the biomass accumulation of S. japonica may well increase under future scenarios of ocean acidification and eutrophication.  相似文献   

Re-evaluation of Morphological Diagnostic Characteristics of <Emphasis Type="Italic">Hexapleomera</Emphasis> Dudich, 1931 (Crustacea: Tanaidacea), with Description of a New Species     

Jin?Hee?Wi  Chang-Keun?Kang  In?Tae?Lee  Hyeon?Gyeong?JeongEmail author 《Ocean Science Journal》2018,53(4):641-653

An undescribed species of Tanaidacea was collected from Yokji Harbor in the southern coast of Korea. Hexapleomera yokjidona n. sp. can be distinguished from other species of the genus by the distinguishing features of a uropod with five articles, a pleopod basal article lacking inner seta, a mandible setal row with two setae, maxilliped coxa with two proximal setae, pereonites 1–3 together longer than wide, and pereopods 2–3 propodus with three ventral setae. To prove that H. yokjidona is a new species, detailed morphological characteristics of both genders are described and a comprehensive comparison among the species of the genus is tabulated. Additionally, diagnostic characteristics previously used to identify the species of Hexapleomera are reassessed and upgraded.  相似文献   

Peculiarities of the abundance of chemical elements in the atmosphere of PMMR23-red supergiant in the Small Magellanic Cloud due to interstellar gas accretion     

A. V. Yushchenko  V. F. Gopka  A. V. Shavrina  V. A. Yushchenko  S. V. Vasileva  S. M. Andrievsky  A. A. Raikov  S. Kim  P. Rittipruk  Y. Jeong  Y.-W. Kang 《Kinematics and Physics of Celestial Bodies》2017,33(5):199-216

The chemical composition of the PMMR23 red supergiant located in the Small Magellanic Cloud (SMC) is analyzed. The abundance of 35 chemical elements and the upper limits of abundance for Tl and U are found. The relative abundance of heavy elements is higher by 0.6–1.0 dex with respect to iron peak elements. The spectra of several SMC red supergiants PMMR27, PMMR28, and PMMR144—located in the region where the velocities of stars and interstellar gas are quite high— show the emission components in the wings of the hydrogen line. This emission is not detected for PMMR23. A possibility of interstellar gas accretion on the atmospheres of PMMR23 and other supergiants in Magellanic Clouds is discussed. The analysis is carried out using spectra measured at ESO 3.6 m telescope with the spectral resolving power R = 30000.  相似文献   

煤的镜质组平均反射率绝对标准差(R_(o,sd))作为配煤参数的应用     

康西栋  胡善亭  潘银苗  王凌志 《地学前缘》1999,6(Z1):61-64

由于煤的镜质组平均反射率不能精确反映镜质组中反射率的分布状况,因此在配煤炼焦研究中,利用镜质组平均反射率作配煤参数往往会有一定的偏差。通过对北京焦化厂原料煤的深入研究和实验,笔者提出一个新的煤岩配煤参数,即煤的镜质组平均反射率绝对标准差（Ro,sd）。该参数是一个将镜质组反射率分布图量化的参数,既可反映煤的变质程度,又能反映原料煤的镜质组反射率分布特征。经验证,利用该参数作为配煤参数能取得更佳炼焦效果。  相似文献   

陶枣煤田晚古生代煤中硫及伴生有害元素分布特征   总被引：10，自引：0，他引：10  

黄文辉  杨起  汤达祯  康西栋  刘大锰 《地学前缘》1999,6(Z1):45-52

对山东陶枣煤田晚古生代洪进行了形态硫分析、煤中黄铁矿伴生无奈的探针测试及煤中微量元素中子活化分析,结果表明,高硫煤中有害物质主要来自煤中黄铁矿,黄铁矿硫占总硫的75％以上,同时黄铁矿中伴生有大量有害元素,其质量分数与种类又与其成因类型有关。黄铁矿中伴生有害元素质量分数约在0．5％至2．5％之间。太原组高硫煤中的有害元素以Cu,As,U,Ph,Mo和Co等为特征,其成因与硫的聚集密切相关。研究还发现,As与Fe存在相关关系,As主要赋存在Fe和Cu的硫化物中。U的富集与海水的影响有关,同时也受岩浆活动的影响。侵入体附近的低灰天然焦含U最高,达10×10－6。根据以上研究结果,推测对于高硫煤采用重液洗选除硫除灰时,也可同时去除大部分有害元素,应予深入研究。  相似文献   

中国某些金矿床中碲化物的特征   总被引：6，自引：0，他引：6  

罗镇宽  关康 《黄金地质》1999,5(3):69-74

我国含碲化物的金矿床主要有４种类型,太古宙花岗－绿岩地体中的含金石英脉型矿床、元古宙火山岩中的蚀变构造岩型金矿床、中－新生代火山岩中的浅成低温热液金银矿床,与花岗岩有关的金矿床。总结了我国已发现的碲化物的光学性质,硬度及其共生组合特征,列出了主要碲化物的电子探针定量分析结果,最后讨论了碲化物形成的某些地球化学习性,碲化物总是与自然金一起形成于矿化的晚期,这表明它与金有某些一致的地球化学习性,并可能  相似文献   

Comparative study on degassing activities along the north fault zone of Western Qinling     

康来迅  张新基  黄杏珍  李立武 《地震学报(英文版)》1999,12(6):716-723

IntroductionIncurrentstudiesofnewactivityofafault,orthecrustmovementandtheeallhdynamics,moreat'tentionshavebeenpaidonthedegassingactivities,andtheutilizationofGPStechniqueandtheseismicitydata(Kan,etal,1979,Li,etal,1993;1998).Beforetheoccurrenceofalargeearthquake,thegassesinnertheearthwillstronglyreleasealongthefaultduetotheactionofthetectonicstressfield.Suchphenomenahasbeendiscoveredandreportedintheearly1970s(Cat,etal,1980).Sincethe1980s,thetechniqueoffaultgashasbeendevelopedrapidlyandthegr…  相似文献