哈尔滨机场冷涡雷暴预报方法初探

本文通过用数值预报产品对冷涡雷暴分析,得出数值预报的形势场、抬升指数、K指数、垂直速度等,对提前预报冷涡雷暴有很好的指示作用。结合卫星云图、雷达回波图,能更好的监控冷涡雷暴的发展演变,为飞行安全提供有力保障。     

Characteristics of oceanic impact‐induced large water waves—Re‐evaluation of the tsunami hazard

Abstract— The potential hazard of a meteorite impact in the ocean is controversial with respect to the destructive power of generated large ocean waves (tsunamis). We used numerical modeling of hypervelocity impact to investigate the generation mechanism and the characteristics of the resulting waves up to a distance of 100–150 projectile radii. The wave signal is primarily controlled by the ratio between projectile diameter and water depth, and can be roughly classified into deep‐water and shallow‐water impacts. In the latter, the collapse of the crater rim results in a wave signal similar to solitary waves, which propagate and decay in agreement with shallow‐water wave theory. The much more likely scenario for an asteroid impact on Earth is a relatively small body (much smaller than the water depth) striking the deep sea. In this case, the collapse of the transient crater results in a significantly different and much more complex wave signal that is characterized by strong nonlinear behavior. We found that such waves decay much more rapidly than previously assumed and cannot be treated as long waves. For this reason, the shallow‐water theory is not applicable for the computation of wave propagation, and more complex models (full solution of the Boussinesq equations) are required.     

Object-oriented Urban Dynamic Monitoring——A Case Study of Haidian District of Beijing

It is crucial to conduct the land use/cover research to obtain the global change information.Urban area is one of the most sensitive areas in land use/cover change.Therefore land use/cover change in urban areas is very im-portant in global change.It is vital to incorporate the information of urban land use/cover change into the process of decision-making about urban area development.In this paper,a new urban change detection approach,urban dynamic monitoring based on objects,is introduced.This approach includes four steps:1)producing multi-scale objects from multi-temporal remotely sensed images with spectrum,texture and context information;2)extracting possible changed objects adopting object-oriented classification;3)obtaining shared objects as the basic units for urban change detection;4)determining the threshold to segment the changed objects from the possible changed objects using Otsu method.In this paper,the object-based approach was applied to detecting the urban expansion in Haidian District,Beijing,China with two Landsat Thematic Mapper(TM)data in 1997 and 2004.The results indicated that the overall accuracy was about 84.83%,and Kappa about 0.785.Compared with other conventional approaches,the object-based approach was advantageous in reducing the error accumulation of image classification of each datum and in independence to the radiometric correction and image registration accuracy.     

PowerBuilder与Sybase在客户／服务器模式下的连接及应用

作者在文中系统地解析了PowerBuilder在客户／服务器模式下与Sybase进行连接及应用的过程。详细说明了如何在PowerBuilder中调用存储过程与Sybase进行接口的方法，并提出如何在PowerBuilder中检查网络状态的方案。     

论沙粒两种起动关系与沙粒跃移的双重性

研究沙粒两种起动关系是深入认识沙粒两种起动效能的继续和发展。文章分析了沙粒两种起动的不同性质，首次把流体起动界定为风蚀性起动，把跃移质冲击起动界定为置换性起动。认为流体起动具有主动分异性，而冲击起动只有随机分异性。根据这些特性对沙粒两种起动效能和沙粒连续移动提出了新义。认为沙粒跃移具有双重性，跃移质有其冲击地表的一面，也有其大量耗能的一面。沙粒两种起动具有兴衰与共的不可分割关系。地表风蚀是沙粒两种起动优势互补相互促进的结果；而地表堆积有时是跃移质耗能过多引起两种起动互相制约的结果。通过多方论证，将沙粒两种起动效能之由传统的19：1，初步改为4：1乃至3：1。     

ROBUST: The ROle of BUffering capacities in STabilising coastal lagoon ecosystems

“Buffer capacities” has been defined in ecology as a holistic concept (e.g., Integration of Ecosystem Theories: A Pattern, second ed. Kluwer, Dordrecht, 1997, 388pp), but we show that it can also be worked out in mechanistic studies. Our mechanistic approach highlights that “buffering capacities” can be depleted progressively, and, therefore, we make a distinction between current and potential “buffering capacities”. We have applied this concept to understand the limited “local stability” in seagrass ecosystems and their vulnerability towards structural changes into macro-algal dominated communities. We explored the following processes and studied how they confer buffering capacities to the seagrass ecosystem: (i) net autotrophy is persistent in Zostera noltii meadows where plant assimilation acts as a sink for nutrients, this contrasted with the Ulva system that shifted back and forth between net autotrophy and net heterotrophy; (ii) the Z. noltii ecosystem possesses a certain albeit rather limited capacity to modify the balance between nitrogen fixation and denitrification, i.e., it was found that in situ nitrogen fixation always exceeded denitrification; (iii) the nitrogen demand of organoheterotrophic bacteria in the sediment results in nitrogen retention of N in the sediment and hence a buffer against release of nitrogen compounds from sediments, (iv) habitat diversification in seagrass meadows provides shelter for meiofauna and hence buffering against adverse conditions, (v) sedimentary iron provides a buffer against noxious sulfide (note: bacterial sulfide production is enhanced in anoxic sediment niches by increased organic matter loading). On the other hand, in the coastal system we studied, sedimentary iron appears less important as a redox-coupled buffer system against phosphate loading. This is because most inorganic phosphate is bound to calcium rather than to iron. In addition, our studies have highlighted the importance of plant–microbe interactions in the seagrass meadows.     

数学建模是培养应用型人才的重要环节

阐述数学建模是一个增强学习能力的过程,是培养跨世纪的应用型科技人才的重要的一环。突出分析能力和创造能力的培养是这门课程的中心任务,计算机的使用也是数学建模的重要技术手段,作为数学教学改革的一门尝试性课程,将在广大高校教师的努力下得到创新和发展     

震后基于无人机快速三维定位被困人员模型研究

针对震后被倒塌建筑物或滑坡埋压的被困人员进行快速定位问题，在阅读大量相关文献的基础上，以无人机遥感、地理信息空间和三维质心定位技术为基础，采用无线信号RSSI测距模型，配合影像范围内基准影像数据辅助定位，构建震后基于无人机快速三维定位被困人员模型。以红河县城区作为研究区，对城区内特定人员进行三维定位，结果表明该模型定位精度高，对震后废墟被困人员营救具有重要意义。     

鄂尔多斯盆地构造沉降特征及对盆地成因的启示

构造沉降作为盆地成因研究中的重要组成部分,对其特征进行分析有助于盆地成因的解析。本次通过对鄂尔多斯盆地内5口典型探井的多期不整合所代表的的剥蚀厚度进行恢复,结合去压实矫正模型以及平均密度、平均古水深等参数的确定,较为精确地刻画出了鄂尔多斯盆地不同构造单元自早寒武世至今的构造沉降特征,同时结合裂谷盆地瞬时拉张模型、裂后热坳陷模型以及前陆盆地挠曲模型对构造沉降曲线进行了模拟,对盆地成因进行分析。鄂尔多斯盆地中寒武世—中生代末期主要由早古生代沉降旋回、二叠—三叠纪沉降旋回与侏罗—白垩纪沉降旋回组成。其中岩石圈热冷却作用引起的沉降贯穿全地质时期。早古生代沉降旋回中,中寒武世的加速沉降主要体现在盆地南部,沉降机制为岩石圈伸展减薄,中奥陶世马家期为全盆地尺度的加速沉降,沉降机制仍为岩石圈伸展减薄。二叠—三叠纪沉降旋回中,晚二叠世—早-中三叠世为该旋回的加速沉降期,该期加速沉降具有多幕裂陷的特征。侏罗—白垩纪沉降旋回中,中侏罗世盆地南部处于缓慢沉降期,沉降机制为岩石圈热冷却作用,晚侏罗世—早白垩世,除伊盟隆起,盆地整体处于加速沉降期,沉降机制为前陆盆地引起的挠曲沉降。