Radio Cherenkov signals from the Moon: Neutrinos and cosmic rays

Neutrino production of radio Cherenkov signals in the Moon is the object of radio telescope observations. Depending on the energy range and detection parameters, the dominant contribution to the neutrino signal may come from interactions of the neutrino on the Moon facing the telescope, rather than neutrinos that have traversed a portion of the Moon. Using the approximate analytic expression of the effective lunar aperture from a recent paper by Gayley, Mutel and Jaeger, we evaluate the background from cosmic ray interactions in the lunar regolith. We also consider the modifications to the effective lunar aperture from generic non-standard model neutrino interactions. A background to neutrino signals are radio Cherenkov signals from cosmic ray interactions. For cosmogenic neutrino fluxes, neutrino signals will be difficult to observe because of low neutrino flux at the high energy end and large cosmic ray background in the lower energy range considered here. We show that lunar radio detection of neutrino interactions is best suited to constrain or measure neutrinos from astrophysical sources and probe non-standard neutrino-nucleon interactions such as microscopic black hole production.     

Particle spectra from acceleration at forward and reverse shocks of young Type Ia Supernova Remnants

We study cosmic-ray acceleration in young Type Ia Supernova Remnants (SNRs) by means of test-particle diffusive shock acceleration theory and 1-D hydrodynamical simulations of their evolution. In addition to acceleration at the forward shock, we explore the particle acceleration at the reverse shock in the presence of a possible substantial magnetic field, and consequently the impact of this acceleration on the particle spectra in the remnant. We investigate the time evolution of the spectra for various time-dependent profiles of the magnetic field in the shocked region of the remnant. We test a possible influence on particle spectra of the Alfvénic drift of scattering centers in the precursor regions of the shocks. In addition, we study the radiation spectra and morphology in a broad band from radio to gamma-rays. It is demonstrated that the reverse shock contribution to the cosmic-ray particle population of young Type Ia SNRs may be significant, modifying the spatial distribution of particles and noticeably affecting the volume-integrated particle spectra in young SNRs. In particular spectral structures may arise in test-particle calculations that are often discussed as signatures of non-linear cosmic-ray modification of shocks. Therefore, the spectrum and morphology of emission, and their time evolution, differ from pure forward-shock solutions.     

棉花和大豆等效散射反照率估算

本文以棉花和大豆为例,基于车载多频率微波辐射计的观测数据,利用最小二乘原理实现对两种典型农作物等效散射反照率的估算,研究了植被层等效散射反照率随观测角度、频率以及植被浓密程度的变化规律,对不同覆盖度情况下植被层的等效散射反照率进行了定性的分析。这一研究结果在以零阶模型为基础进行地表参数反演时,对于植被层等效散射反照率的确定具有重要的理论参考价值。     

基于背景信息的MODIS林火自动提取算法

本文在火点提取算法中加入了背景信息,减少了伪火点,提高了火点提取算法的准确性和可靠性。通过选取江西省武宁县为实验区,应用MODIS数据进行了火点的提取,实现了从数据的处理到火点的自动提取。经实验验证后,发现改进后的算法火点提取精度较高,能很好地满足林火监测要求。     

面向矿产行业的GIS卓越工程师培养模式研究

针对现有GIS专业培养方案难以适应社会发展需求的问题,本文以国家"卓越工程师教育培养计划"为契机,依托我校矿物资源工程优势学科的矿产行业背景,对GIS专业的实践教学计划与内容进行改革,探索了校内特色专业实验室、校外典型行业实践基地和双师制行业实践的3种教学模式,构建出培养具备高素质矿产行业背景GIS卓越工程师培养的"四四"实践教学平台。并在开放式矿业教学平台的支持下,研究了"学习—实践—研究—创新—再学习"为主线的实践教学方法,达到提升GIS专业学生行业应用能力的目的。     

2012年5月28日河北省唐山4.8级地震

2012年5月28日河北省唐山市古冶区与滦县交界发生4.8级地震,地震宏观震中位于古冶区的王辇庄乡.震中烈度为V度,地震发生在NE走向的唐山断裂带附近.地震没有造成人员伤亡和经济损失.震源机制解P轴方位为SEE,T轴方位为SSW,接近水平,这与华北构造应力场的NE-NEE方向不一致.唐山4.8级地震是1976年唐山7.8级地震晚期余震的正常起伏,2004年以来唐山老震区的ML4.0以上地震呈现了很好的准周期性.唐山4.8级地震前地震活动性和测震学参数存在背景性异常,从不同角度反映了老震区地震活动平静、起伏的阶段性特征.前兆异常以中短期异常为主,其中地下流体异常、电磁异常表现更为突出.此次地震虽然震级不高,但无论是地震活动性还是前兆方面都出现了一定数量的异常.异常既有趋势性的,也有短临的,配套性很好.     

山西省内连续5次ML≥4.0地震序列震源区附近应力降的初步研究

在对山西地区的非弹性衰减系数、场地响应和震源新参数各量关系初步研究之后,利用山西地区2008年8月-2012年5月间发生的ML2.0级以上地震612次,计算其中148次地震的震源新参数.着重研究该时间段内山西地震带连续发生的5次ML4.0级以上地震震源区的背景应力降,阳曲震区的平均应力降为2.586 MPa,其它4个震区都在1～2 MPa间.分析发现山西中部的阳曲震源区、原平震源区、大同震源区震后应力降趋于平稳的低位,而山西中南部地区的洪洞、河津2震源区附近的地震应力降在震后仍处于不断积累、逐步增强的趋势,所以应密切关注山西中南部地区的震情形势.     

2D磁异常分步反演方法分析研究

2D磁异常分步反演方法是利用二维(剖面)磁测数据确定场源几何参数以及物性参数的一种反演方法,该方法的优点是构造的形态函数S不受场源磁化特征的影响,因此可以在未知场源物性参数的前提下,通过拟合依次反演得到磁性源形体横截面几何参数、磁化强度以及磁化方向.本文阐述了2D磁异常分步反演方法的原理及步骤,对形态函数S的特征及求取方法进行了讨论,分析了区域背景干扰(正常场)对反演结果的影响并提出了初步解决方案.在方法研究的基础上,进行了单一理论模型及组合理论模型的试算,得到了较好的反演结果.为了验证该方法的效果,对实测剖面进行了试算,得到了场源的边界及场源埋深信息,为进一步反演提供了有用的参考.     

Spaceborne Microwave Remote Sensing of Arctic Sea Ice During Spring

This paper outlines the fundamental roles sea ice plays during the spring Arctic climate, and it demonstrates the use of passive microwave remote sensing in measuring climatically important sea ice variables during the spring transitional period. It discusses the theoretical concepts underlying passive microwave remote sensing of sea ice, and it summarizes the historical use of satellite microwave radiometry in the Arctic region. In addition, this paper discusses the derivation of climatically important sea ice variables, including sea ice extent, concentration, multiyear ice fraction, and snow melt onset, with additional comments on the precision and accuracy of the remote sensing estimates. It also discusses interannual trends in sea ice extent and presents interannual trends in snow melt onset dates. Finally, this paper provides a brief discussion on the future directions in passive microwave remote sensing of climatically important sea ice variables during the spring transitional period.     

西天山乌孙山地区大哈拉军山组火山岩LA-ICP-MS锆石U-Pb年龄及其构造环境

西天山乌孙山地区大哈拉军山组由玄武岩、安山岩、英安岩、流纹岩及相应的火山碎屑岩组成,安山岩和流纹岩分布最广。LA-ICP-MS锆石U-Pb定年结果表明,火山活动喷发的安山岩与安山质晶屑凝灰熔岩分别形成于353.9Ma±6.5Ma和356.3Ma±4.4Ma,属于早石炭世早期。通过区域对比,西天山大哈拉军山组的火山岩浆作用显示从伊犁中天山板块南北缘向伊犁盆地内部逐渐变年轻的特点,且火山岩喷发时代差别不大(约40Ma)。岩石地球化学研究表明,火山岩属钙碱性系列,富集轻稀土元素,相对亏损重稀土元素。中性火山岩富集大离子亲石元素(如Cs、Rb、Th、U),而相对亏损高场强元素,具有明显的Nb、Ta、Ti负异常,显示出岛弧火山岩的特征;酸性火山岩相对富集Rb、Th、U、Ta等元素,具有明显的Ba、Sr、P、Eu、Ti等元素的负异常。综合伊犁-中天山板块南缘的构造演化特征,认为大哈拉军山组形成于活动大陆边缘环境,产在板块俯冲-碰撞的最后阶段。