延川南地区下石盒子组致密砂岩气储层特征及成藏条件     

李理 《中国煤炭地质》2013,(8)

延川南地区位于鄂尔多斯盆地东南缘晋西挠褶带与渭北隆起交汇处,区内2口钻井在盒6、盒8段试气获得中-高产气流。在前人研究的基础上,对下石盒子组致密砂岩气储层的沉积相类型、储集空间特征、储层物性以及影响气藏发育的主控因素进行分析,认为下石盒子组产气层位一般发育在河道的砂体富集带的心滩微相,储层岩石类型以长石岩屑质石英砂岩为主,岩屑砂岩、岩屑质石英砂岩次之。研究区河道砂体富集带在上部受泥岩封盖,侧向上受逆断层遮挡,形成岩性-地层复合型气藏。  相似文献   

BL Lacertae： Hard Optical Spectrum and GeV γ-ray Emission     

Shan-Jie Qian  Xi-Zhen Zhang  T P Krichbaum National Astronomical Observatories  Chinese Academy of Sciences Beijing Max-Planck-Institut für Radioastronomie Auf dem Hügel Bonn Germany 《中国天文和天体物理学报》2004,4(3):231-246

The spectral energy distribution (SED) of the γ-ray flare observed in July 1997 in BL Lacertae is re-considered. It is pointed out that the optical observations made by Webb et al. showed the associated optical flare has a hard spectrum (the average spectral index αopt～0.48, Fν∝ν^-α), and the ASCA observations made by Tanihata et al. showed very steep spectra in the soft X-ray band (0.7-1.5 keV) (αx～3-4). We find that the flux densities and spectral indices in both the optical and soft X-ray bands are closely consistent with a ‘canonical‘ synchrotron spectrum emitted by relativistic electrons of a power-law energy distribution with a high energy cutoff, and thus the peak of the SED of the synchrotron radiation (in representation of νFν) is located in the EUV - soft X-ray bands. Therefore, the GeV γ-ray emission observed in the July 1997 outburst may be mainly due to the synchrotron self-Compton (SSC) process, contrasting with the current explanations in terms of external radiation Compton (ERC) process, in which the seed photons are mostly taken to be the UV emission from the clouds of the broad emission line region. We argue that the hard optical spectra observed during the γ-ray outburst may be an important signature for the acceleration of high energy electrons (γe-10^4) in the γ-ray emitting region.  相似文献   

双星系统中大质量比致密天体质量四极矩对轨道频率的影响分析     

万程凯  韩文标  江春华 《天文学进展》2020,(1):96-105

极端质量比旋进系统是空间引力波探测器最重要的波源之一。对引力波的探测需要高精度波形模版。当前主流的极端质量比旋进系统引力波计算模型中,人们一般将小质量天体当作试验粒子进行计算,而忽略了其结构及自身引力对背景引力场的影响。利用Mathisson-Papapetrou-Dixon方程研究延展体在弯曲时空中的运动,以及小天体自旋和质量多极矩对引力波信号识别产生的影响。结果表明,质量比在10?6-10?4范围的旋进系统,其自旋达到很大时,自旋对延展体的轨道运动有不可忽略的影响;在质量比10?4-10?2区间内,需要考虑中心黑洞潮汐作用导致的白矮星形变;在质量比大于10?4,且白矮星自旋很大时,其自旋产生的形变会对小天体轨道运动产生不可忽略的影响。大质量黑洞潮汐作用导致的恒星级黑洞或中子星产生的形变可以忽略,中子星和黑洞的自旋会对轨道运动产生不可忽略的影响,而自旋产生的四极矩对轨道运动不产生影响。  相似文献   

Empirical population synthesis for 74 blue compact galaxies     

X. Kong 《Astrophysics and Space Science》2003,284(2):905-908

We have observed the largest optical spectra sample of 97 blue compact galaxies. Stellar population properties of 74 star-forming BCGs of them were derived by comparing the equivalent widths of strong absorption features and continuum colors, using a method of empirical population synthesis based on star cluster sample. The results indicate that blue compact galaxies are typically age-composite stellar system, the continuum flux fractions at 5870Å due to old stellar components and young stellar components are both important for most of the galaxies. The stellar populations of blue compact galaxies present a variety of characteristics, and the contribution from different age and metallicity components is different. The star formation episodes are usually short, some galaxies maybe undergoing their first global episode of star formation, while for the most sample galaxies, older stars contribute to at most half the optical emission. Our results suggest that BCGs are old galaxies, in which star formation occurs in short intense burst separated by long quiescent phases.  相似文献   

Dynamics and gravitational waveforms in spinning compact eccentric binaries     

《New Astronomy》2014

The effects of eccentricity on the Hamiltonian dynamics of post-Newtonian spinning compact binaries and gravitational radiation from eccentric orbits are discussed. The simulation results of scans for chaos show that the eccentricity has a great effect on the dynamics without considering dissipation due to gravitational radiation. Moreover, both the dynamics behavior and the orbital eccentricity jointly modulate the gravitational waveforms, and the spin–spin coupling effect play an important role during the gravitational radiation of inspiral and coalescence. Moreover, the imprint of characteristic of the original system can be deduced from the time-domain and frequency-domain waveforms.  相似文献   

紧凑城市空间结构对城市能耗的作用机制——基于江苏省的实证研究   总被引：2，自引：0，他引：2  

韩刚  袁家冬  张轩  冯学良 《地理科学》2019,39(7):1147-1154

以江苏省为研究对象,选取2007~2016年数据资料,探讨城市紧凑发展与能耗间的作用关系。首先计算城市紧凑度和能耗数值,紧凑度通过构建评价指标体系测算,包括土地利用、经济、人口、基础设施、公共服务5个一级指标以及12个二级指标,城市能源消耗以全社会用电总量、天然气供气总量、液化石油气供气总量折算标准煤方式获取。其次,将江苏省城市紧凑度和能耗数值进行空间可视化,观察两者在4个时间节点,地域和时空上的演变。最后,运用灰色关联分析法和计量经济学中的普通最小二乘法及一阶差分广义矩估计,对城市紧凑度与能耗的相关关系、作用机制进行定量研究。通过研究发现,江苏省城市紧凑度和能耗皆存在空间上的集聚分布特征,且两者具有较强的相关性,紧凑度的提升对能耗有显著的抑制作用,但这种作用表现出较为典型的时效性和滞后性,城市空间结构调整所带来的效用增长会缓慢作用于能源利用结构。  相似文献   

基于GIS和DEA的特大城市空间紧凑度与城市效率分析   总被引：5，自引：2，他引：3  

郭腾云  董冠鹏 《地球信息科学学报》2009,11(4):482-490

利用GIS分析工具、数据包络分析方法及Malmquist模型方法,对我国特大城市空间紧凑度、城市效率及其变化,以及它们的相关关系进行深入研究发现:(1)特大城市空间形态呈现出紧凑变化趋势。(2)紧凑度提高的城市数明显多于紧凑度降低的城市数,极高紧凑度和极低紧凑度的特大城市数均呈一定的增加趋势。(3)特大城市效率水平一般,其中,只有少数城市效率达到了效率最优。(4)1990-2000年特大城市效率水平呈现一定的提高趋势,其中城市效率(纯技术和规模效率)呈现弱提高趋势,技术进步和全要素生产率则呈较明显的提高趋势。(5)特大城市的空间紧凑度与城市效率之间存在一定的互动关系:随着特大城市空间紧凑度的提高,城市要素资源的配置和利用水平得到了一定的改善,城市效率提高了;城市空间紧凑度变化率越高,城市效率提高的趋势也越明显,反之,则下降趋势也越明显;(6)城市空间紧凑度变化与城市技术变化不存在互动关系。  相似文献   

Spectral Reversal and Stratification of the Jet in 3C 273     

Shan－JieQian  Xi－ZhengZhang 《中国天文和天体物理学报》2001,1(4):296-304

Quasi-simultaneous VLBI observations at 15-86 GHz have shown that in the classical superluminal radio source 3C 273, the spectral index α(Sv∝v^α) has a systematic variation along the jet. For epoch 1995.15, a spectral reversal was observed at core distance -1.5mas, where the superluminal knot C12 Located. Similarly, for epoch 1997.18, two spectral reversals wrer observed at core distances of -1.8 mas and -4.2 mas ,where superluminal knots C11 and C14 were, respectively. These spectral reversals are associated with local maxima of the jet width. We suggest that this phenomenon may be related to a stratification of the jet structure, i.e., its physical parameters (flow velocity, Doppler factor, electron density and energy, magnetic field strength,etc.) are substantially dependent on the distance from the jet axis. These properties may be naturally formed through gasdynamic processes when the jet expands into a lower pressure ambient medium.  相似文献   

Iceberg Detection Using Compact Polarimetric Synthetic Aperture Radar     

Michael Denbina 《大气与海洋》2013,51(4):437-446

In recent years, the use of synthetic aperture radar (SAR) for iceberg detection has been increasing thanks to the greater availability and coverage of SAR data, particularly polarimetric data. Greater amounts of polarimetric information can increase detection performance, preventing false alarms and missed detections. However, quad-polarization (quad-pol) SAR systems have increased data rate and power usage requirements, causing quad-pol modes to have generally half the swath width of dual-polarization (dual-pol) modes. Compact polarimetry is a compromise that allows the approximation of quad-pol information (referred to as “pseudo quad-pol”) using a dual-pol SAR. In this paper, using compact polarimetric data simulated from RADARSAT-2 quad-pol imagery, we show how pseudo-quad-pol data can be used for iceberg detection using the likelihood ratio test method. We show that use of the pseudo-quad-pol HV intensity can augment the detection performance of a compact polarimetric SAR system. We also compare the performance of the various compact polarimetric configurations to linearly polarized dual-pol and quad-pol data.

[Traduit par la rédaction] Ces dernières années, le radar à synthèse d'ouverture (RSO) a été de plus en plus utilisé pour la détection des icebergs grâce à une meilleure disponibilité et une meilleure couverture des données RSO, en particulier des données polarimétriques. De plus grandes quantités d'informations polarimétiques peuvent améliorer la performance de détection, ce qui évite les fausses alarmes et les détections manquées. Cependant, les systèmes RSO à quadruple polarisation (quad-pol) exigent des débits binaires et une consommation d’énergie plus élevés, de telle sorte que les modes quad-pol utilisent généralement une largeur de couloir la moitié moindre que celle des modes à double polarisation (dual-pol). La polarimétrie compacte est un compromis qui permet d'approximer l'information quad-pol (alors appelée « pseudo-quad-pol ») au moyen d'un RSO dual-pol. Dans cet article, en utilisant des données de polarimétrie compacte simulées à partir de l'imagerie RADARSAT-2 quad-pol, nous montrons comment les données pseudo-quad-pol peuvent servir à la détection des icebergs au moyen de la méthode du test du rapport des vraisemblances. Nous montrons que l'utilisation de l'intensité HV pseudo-quad-pol peut augmenter la performance de détection d'un système RSO polarimétrique compact. Nous comparons aussi la performance des diverses configurations polarimétriques compactes aux données dual-pol et quad-pol linéairement polarisées.  相似文献   

热压高磷铁基胎体性能及其金刚石钻头研究          下载免费PDF全文

阎冠欣 《探矿工程》2009,36(5):75-77,80

针对在硬而致密岩石中钻进时效低和钻头使用寿命短以及传统金刚石钻头胎体材料价格高等众多难题,采用混料回归试验设计方法,进行了替代碳化钨基金刚石钻头胎体材料的新型铁基胎体配方的试验研究;分析了热压钻头的金刚石出刃与岩石研磨性等岩性之间的内在联系,认为钻头的胎体成分及其性能是关键。因此,从热压金刚石钻头的胎体成分与性能研究入手,经过反复的试验研究与优化组合,研究出热压高磷铁基孕镶金刚石钻头的胎体材料,并试制出金刚石钻头。在室内对可钻性Ⅸ级岩石进行钻进的试验表明：钻进时效平均达到1．91m,钻头平均工作寿命达到60．26m。试验结果表明,高磷铁基眙体是一种性能良好的金刚石钻头胎体材料,且该类型胎体的热压金刚石钻头是一种成本明显降低、具有广谱性能的金刚石钻头。  相似文献