A new approach to GPS ambiguity decorrelation

Ambiguity decorrelation is a useful technique for rapid integer ambiguity fixing. It plays an important role in the least-squares ambiguity decorrelation adjustment (Lambda) method. An approach to multi-dimension ambiguity decorrelation is proposed by the introduction of a new concept: united ambiguity decorrelation. It is found that united ambiguity decorrelation can provide a rapid and effective route to ambiguity decorrelation. An approach to united ambiguity decorrelation, the HL process, is described in detail. The HL process performs very well in high-dimension ambiguity decorrelation tests. Received: 9 March 1998 / Accepted: 1 June 1999     

重磁三维反演伊犁盆地中部密度和磁性结构

伊犁盆地中部区域地处多个构造单元的交汇区,构造复杂,缺乏高精度地质资料,制约了对盆地构造演化的进一步认识.本文联合使用多种先验信息作为约束条件,利用高精度重磁数据反演获得了研究区地下海拔-10 km以浅的三维密度和磁性结构,增强了反演结果的可靠性.结果揭示以白石墩次凸为中心发育了一个"北断南超"的南西-北东向不对称型凹陷,北部沉积厚度大于南部;区内主要断裂具有高角度特征,生烃中心受断裂控制,阿吾拉勒山前凹陷浅部可能发育逆掩断裂;火成岩以侵入的基性火成岩为主,伴有部分喷出火成岩和中酸性火成岩.     

2008年10月西藏当雄MW6.3地震震后形变提取与余滑反演

2008年10月6日西藏当雄发生M_W6.3地震.本文利用震后2008年10月26日至2010年8月22日的16期ENVISAT ASAR数据,通过小基线集干涉测量、误差校正与MInTS（Multiscale InSAR Time Series）技术提取高精度的震后形变场,利用SDM（Steepest Descent Method）方法反演断层震后余滑演化过程,并分析震后余滑与同震滑动的关系.结果表明：当雄M_W6.3地震的近场震后形变场主要位于断层西侧,在时间演化上具有明显的对数函数衰减规律;震后余滑主要集中于断层中南段深0~15 km区间,最大的余滑量约0.07 m,位于断层深约9.28 km处,滑动角约-103°;震后余滑引起的地震矩能量M₀与矩震级M_W在时间演化上具有指数函数递增规律;当剪切模量μ=32 GPa,震后665天余滑释放的地震矩能量约为1.92×10¹⁷N·m,约占同震滑动释放地震矩的4.8%,相当于矩震级M_W5.46;虽然震后余滑已经延伸到断层浅部0~5 km区间,但由于余滑量相对较小,没有改变同震滑动在断层浅部区域的滑动亏损现象,这可能是2010年11月30日该区域又发生M_W5.3级余震的主要原因之一.     

基于MapInfo的COM回调机制开发GIS应用

Microsoft.NET是微软公司推出的新平台,具有强大的全方位技术兼容性。另外,目前基于微软平台的软件通信几乎都是COM实现的,而MapInfo软件是应用广泛的主流GIS软件之一。本文主要结合COM和MapInfo实现GIS的应用开发,即利用.NET的COM组件封装技术实现MapInfo相关接口的打包封装,之后利用.NET的COM回调机制——实现更具简便性与灵活性的GIS应用。本文详细探讨了该机制在实现MapInfo二次开发中的具体思路及关键技术点,取得了较为满意的应用效果。     

Mathematica软件在计算有限单元法系数矩阵中的应用

以一维分层连续介质大地电磁有限元模拟为例,应用Mathematica软件计算系数矩阵。节约了大量的推导时间。确保快速、准确地得到有限元系数矩阵。展示了mathematica软件在计算有限单元系数矩阵中的强大功能。     

Laboratory investigations of the role of biofilms on stream-bed surfaces in debris-flow runout

Debris-flow runout is a fascinating process to understand due to its implications for downstream alluvial fans. Based on the propagation-deposition behaviors of the Dongyuege (DYG) debris flow, in Yunnan, the effect of biofilms on channel surfaces on debris-flow runout is investigated in laboratory flumes with two different internal surfaces: surfaces are lined with granite slabs (Model I) and gravel (Model II), respectively. Our results show that biofilms can significantly reduce frictional resistance to flows. They increase flow velocities, slow down the deceleration of the snouts, prolong runout distances, and subsequently extend the areas covered with resulting deposits, thus greatly assisting the propagation of experimental debris flows. Slippery biofilms consisting mainly of diatoms and their extracellular mucus (ECM) reduce the contact friction between the flume-beds and the overlying fluids, and greatly promote the propagation of tested flows. Well-developed biofilms are found on the underwater channel surfaces of the DYG Creek. Acting as lubricating layers, they likely played a key role in the DYG debris-flow runout. Most of the debris transported during the DYG event was deposited on overbanks, and the sediment that caused the disaster was transported to the populated fan region through the stream-bed clad in the thick biofilms. Owing to their impacts on the development and width of the temporary debris dam breach, the stream-bed covered with biofilms became a direct contributor to the debris-flow hazard. Because of the ubiquitous presence of biofilms on mountain stream-bed surfaces, the development of perennial streamflows can be viewed as an indicator of gully susceptibility to debris flows threatening creek fans. The underwater areas of pre-event channel cross-sections should be regarded as slip or low-friction boundaries, and the parts above stream-levels can be viewed as no-slip boundaries. © 2019 John Wiley & Sons, Ltd.     

Effect of spatially variable saturated hydraulic conductivity with non-stationary characteristics on the stability of reservoir landslides

Stochastic Environmental Research and Risk Assessment - Conventional landslide analyses, based on deterministic methods or simple random variable methods, cannot consider the spatial variability...     

棘皮动物神经肽结构与功能研究进展

神经肽作为一种古老的信号分子,在动物的行为和生理过程中发挥着重要作用。近年来,随着生物信息学和分子生物学技术的发展,大量神经肽得以发掘和揭示,其中海洋生物（棘皮动物）神经肽信号系统及其功能研究亦取得了一定进展。本文对棘皮动物神经肽相关研究进展成果进行了归纳与总结,综述了主要神经肽结构、信号系统、功能及进化地位,并对其今后研究发展趋势进行了展望。     

伶仃洋河口泥沙絮凝特征及影响因素研究

泥沙絮凝对河口细颗粒泥沙运动过程起着极其重要的作用。本文通过LISST-100激光粒度仪等仪器实测伶仃洋河口2013年洪季悬浮泥沙絮凝体现场粒径及水动力、泥沙条件,结合实验室悬沙粒径分析,研究大小潮期间伶仃洋河口泥沙絮凝特征,探讨紊动剪切强度、含沙量、盐度分层及波浪等因素对伶仃洋河口泥沙絮凝的影响。结果表明:伶仃洋河口水体中现场粒径平均值为148.53 μm,大于实验室悬沙分散粒径36.74 μm,河口絮凝现象明显;沉速与有效密度、粒径呈正相关,絮团平均有效密度为153.49 kg/m3,平均沉速达1.13 mm/s;小潮时絮团平均粒径大于大潮,垂向上表底层絮团粒径小、中层大,中底层絮团沉速大于表层。伶仃洋河口水动力、泥沙条件是影响其泥沙絮凝的重要因素,低剪切强度（小于5 s-1）、低含沙量（小于50 mg/L）及高体积浓度有利于细颗粒泥沙之间的相互碰撞,促进絮凝作用;当剪切强度与颗粒间碰撞强度高于絮团所能承受的强度时,絮团易破碎分解成小絮团或更细的泥沙颗粒;伶仃洋河口盐度层化引起的泥沙捕获现象增大中层泥沙体积浓度,有利于中层絮凝体的发育;观测期相对较大的波浪增强水体紊动,增大了水体细颗粒泥沙的碰撞几率,表层絮团粒径随波高峰值的出现而增大。     

石岛湾四种常见鱼类的热耐受性比较研究

作者分别采用动态法和静态法两种实验方法,以石岛湾4种常见鱼类(许氏平鲉(Sebastes schlegeli)、大泷六线鱼(Hexagrammos otakii)、褐菖鲉(Sebastiscus marmoratus)和矛尾虎鱼(Chaeturichthys stigmatias))为研究对象,对比研究了在4个季节基础水温(5.0~26.0℃)和9个温升速率(0.5~15.0℃/h)下这些鱼类的热耐受性。结果表明,4种鱼类的CTM(最大临界温度)和24 h UILT_(50)(24 h高起始致死温度)均与基础水温呈显著正相关,温升速率对鱼类耐热性的影响因鱼种和季节基础温度而异;相同基础水温下4种实验鱼类的CTM值均高于24 h UILT_(50)。4种鱼类的24 h UILT50依次为:矛尾虎鱼许氏平鲉褐菖鲉大泷六线鱼。