基于 Keystone 变换的俯冲加速运动 SAR 成像算法

俯冲加速条件下的SAR成像算法是当前SAR成像领域中一个热门研究课题。受到加速度的影响,其距离方程不再是单纯的双曲线形式,从而导致无法根据驻定相位原理求得俯冲加速SAR回波的二维频谱解析表达式。因此,传统SAR频域成像算法不再适用于俯冲加速SAR成像。论文从SAR距离徙动特性着手,利用Keystone变换实现对俯冲加速SAR的线性徙动校正,从而实现距离向和方位向的二维解耦合,得到最终的SAR聚焦图像。     

求解约束优化问题的动态目标迁移差分进化算法

针对约束优化问题的特点,给出一种改进差分进化算法.将差分进化算法做了适当修正,在初始化中加入迁移操作,依据违反约束度函数和原目标函数进行选择操作,当个体的违反约束度在容忍度以外时,通过违反约束度函数更新个体,当个体的违反约束度在容忍度以内时,通过原目标函数更新个体,实验研究结果表明该算法能有效求解约束优化问题.     

JAK激酶抑制剂AG490阻滞乳腺癌MCF-7的侵袭和迁移

目的 探讨JAK/STAT3和MAPK/ERK1/2两条信号通路的交联作用及其对乳腺癌MCF-7细胞侵袭迁移的影响机制.方法 在乳腺癌MCF-7中,分JAK酶抑制剂AG490未处理组和处理组,Western blot检测磷酸化和非磷酸化STAT3和ERK 1/2蛋白的变化,RT-PCR检测STAT3、ERK1/2 mRNA的变化,明胶酶谱法检测MCF-7分泌MMP-2、MMP-9的变化,同时应用Transwell小室对细胞侵袭迁移能力进行研究.结果 AG490处理MCF-7细胞后,磷酸化和非磷酸化STAT3和ERK1/2蛋白均减少,STAT3、ERK1/2 mRNA转录水平也下降,同时也观察到了AG490能使MCF-7分泌MMP-2和MMP-9减少,从而显著降低了MCF-7细胞的侵袭迁移能力.结论 AG490可阻断JAK/STAT3和MAPK/ERK1/2两条信号通路,抑制MCF-7细胞分泌MMP-2和MMP-9,从而抑制了其侵袭迁移.     

季节冻土区高速公路路基含水状况与冻害调查

冻胀形成的纵向裂缝和道路翻浆导致的沉陷鼓包及车辙变形是季节冻土区高速公路路基冻害的主要形式。野外调查的大量资料表明,地下水是导致路基冻害的最积极活跃的因素。它不仅侵袭软化路基,增加其冻胀,而且侵袭防冻砂砾层甚至底基层,使其失去防冻作用和辅助承载作用,致使道路翻浆破坏。这种水分来源不一定都是地下水由下向上的竖向迁移,地面水也可通过路肩边坡、失效排水沟、路面裂缝和中央分隔带等部位侵袭到路基中来,从而使路基土和结构层材料性能恶化。     

客运站数据迁移方法的研究

数据迁移是企业利用计算机系统进行数据库管理时经常会面临的一个问题.通过对两种数据库管理系统(Microsoft SQL Server和Sybase SQL Server)所提供的数据转换方法的综合分析,结合铁路车站实际工作经验,介绍利用Power Builder前端开发工具在同种和不同种数据库管理系统中进行数据迁移的实现方法.     

船舶内燃机工作过程中颗粒横向迁移的实验研究

为了研究船舶内燃机工作过程中颗粒浓度的再分布问题，本文对层流流动中单个颗粒横向迁移的动力学机理进行了实验研究。采用自行研制的“CCD颗粒轨迹记录装置”记录了层流圆管入口段中单个颗粒的运动轨迹。实验表明，当颗粒超前于当地流体速度时，向管壁迁移；落后于当地流作速度时，向管心迁移。实验结果与理论分析一致。     

探地雷达钢筋正演模拟及偏移成像研究

探地雷达（ground penetrating radar,GPR）在工程检测领域应用广泛,特别是应用于隧道衬砌结构检测。利用时域有限差分方法（finite difference time domain,FDTD）和完全匹配层（perfect match layer,PML）吸收边界条件,采用900 MHz天线,模拟了不同间距、不同深度、不同对应位置的单、双层钢筋混凝土结构,并运用频率-波速域（F-K）波动方程偏移技术分别进行了成像处理。研究表明： 1）有效探测范围内钢筋间距、埋深越大时,干扰信号越少,钢筋的反映越明显; 2）F-K偏移可较好地分辨出单层（上层）钢筋,斜对双层钢筋的分辨率比正对高。     

Experiments on the survival of six brackish macro-invertebrates from the Baltic Sea after dredged spoil coverage and its implications for the field

Physical disturbance by disposal of dredged materials in estuarine and coastal waters may result in burial of benthic fauna. Survival rates depend on a variety of factors including the type and amount of disposed materials and the lifestyle of the organisms. Laboratory burial experiments using six common macrobenthic invertebrates from a brackish habitat of the western Baltic Sea were performed to test the organisms' escape reaction to dredged material disposal. Experimental lab-results were then extrapolated to a field situation with corresponding bottom topography and covering layer thicknesses at experimental field disposal study sites. Resulted survival rates were then verified by comparison with results of an earlier field study at the same disposal sites.Our experimental design in the lab included the disposal of two types of dredged material (i.e. ‘till’ and ‘sand/till mixture’) and two covering layer depths (i.e. 10–20 cm and 14–40 cm). All three bivalves Arctica islandica (Linnaeus), Macoma balthica (Linnaeus), Mya arenaria (Linnaeus) and the polychaete Nephtys hombergii (Savigny) successfully burrowed to the surface of a 32–41 cm deposited sediment layer of till or sand/till mixture and restored contact with the overlying water. These high escape potentials could partly be explained by the heterogeneous texture of the till and sand/till mixture with ‘voids’. The polychaete Bylgides (Harmothoe) sarsi (Malmgren) successfully burrowed through a 16 cm covering layer whereas the polychaete Lagis koreni (Malmgren) showed almost no escaping reaction. No general differences in escape behaviour after burial were detected between our test species from the brackish habitat and those reported in the literature for the same species in marine environments. However, a size-dependence in mobility of motile polychaetes and M. arenaria was apparent within our study. In comparison to a thick coverage, thin covering layers (i.e. 15–16 cm and 20 cm) increased the chance of the organisms (N. hombergii and M. arenaria) to reach the sediment surface after burial. This was not observed for the other test species. While crawling upward to the new sediment surfaces burrowing velocities of up to 8 cm d^− 1 were observed for the bivalves and up to 20 cm d^− 1 for N. hombergii. Between 17 and 79% of the test organisms showed burrowing activity after experimental burial. The survival rate (defined as the ability to regained contact with the sediment surface) ranged from 0 to 33%, depending on species and on burial depth. The organisms reached the sediment surface by burrowing (polychaetes and bivalves) and/or by extending their siphons to the new sediment surface (bivalves). The extrapolation of laboratory survival rates to the two disposal sites was obtained based on the in situ thicknesses of the dredged spoil layers measured by multi-beam echo sounder. This resulted in total average survival rate estimates for the test species of 45 and 43% for the two disposal sites. The results obtained during the laboratory tests and the following extrapolation to the field were verified by the range of results from a previous field study, using grab sampling shortly before and after a disposal event in June 2001. The effect of dredged material disposal on the tested Baltic Sea benthic macrofauna was assessed by extrapolating the verified laboratory results to the field.     

长大高速公路隧道瓦斯人工检测及日常管理

文章依托成都至自贡至泸州高速公路马鞍山隧道工程,详细介绍了隧道瓦斯的人工监测方案及其日常管理维护内容,为今后长大高速公路隧道的安全施工及营运提供参考。     

考虑边界条件不确定性的城市交通拥塞风险分布迁移规律研究

为分析交通联通边界(交通量、交通扩散系数)对特定城市研究区域内交通拥塞迁移规律的影响机理。本文从新的角度考虑城市交通拥塞风险分布迁移规律，将污染质迁移数值模拟模型运用到城市道路交通拥塞风险迁移中。首先对贵阳某区域2020年6~7月的城市交通调查数据及爬取的部分高德地图数据进行处理，并将研究区域以交通联通边界、交通隔断边界、区域分区边界划分为区域1和区域2。在此基础上考虑交通联通边界并建立基于城市交通拥塞风险分布及迁移数值替代模型，并运用Monte Carlo方法对贵阳某研究区域的输入输出结果进行统计分析，并将实际路网数据值输入替代模型，将结果与路网真实情况和高德地图情况进行对比，所建立模型 的预测精度比高德地图高3.7%，且模拟交通拥塞风险迁移规律较高。结果表明，交通联通边界对城市交通拥塞迁移数值模拟模型预报有很大影响，统计分析研究区域模拟模型的结果，可以有效评估不同交通联通边界条件对研究区域交通拥塞风险分布情况和准确预报研究区域内遭受不同 交通拥塞程度的风险。综上可知，本文建立的模型能高效精准分析城市交通拥塞的风险分布迁移规律，可为城市路网分区分段分点治理交通拥塞提供新的参考。