GPS自适应调零天线

本介绍了有关GPS自适应调零天线的各种研究结果，这些研究是1997年根据MITRE公司倡导的研究计划开展的。根据该计划，MITRE公司已经证明了采用微带片辐射体实现基模和高次模已切实可行，从而能在地平线附近形成一个零点的简单而廉价的自适应天线就应运而生。我们知道，由于在地平线附近的干扰威胁最大，所以对这种天线的研究有很大的实用价值。为了减小GPS微带天线大的后瓣，构建了电阻渐变的若干个接地板，并对其进行了测试。天线就安装在接地板上，而接地板外缘的散射恰恰是使微带天线后瓣变大的原因。采用电阻渐变的接地板的自适应天线后，后瓣可降低10－20dB，因此，这类天线有较好的抗干扰能力。通过按比例缩小模型进行测量和分析所作的种种研究，确定了机载平台对GPS自适应天线抑制干扰性能的限制。我们以典型的1：8比例模型对右旋圆极化GPS天线的方向图进行了测量。为了研究装在巡航导弹上的GPS微带天线对平台的影响，我们也作了大量的电磁分析。通过与测量值的比较，仿真的精度得到了验证。这些研究有助于通过电磁效应定量分析对机载天线阵调零性能的影响。所述的电磁效应涉及平台的有限尺寸及曲率、高路径、蠕缓波以及自适应阵中主阵元与辅助阵元之间的互耦。     

用经验法预估垂直折光差角

<正> 在建造稀有工程建筑物时,在特殊用途的工作项目和其它领域内,计入大气折光是提高控制网测角精度的一个重要因素。为此,用大地测量方法来研究大气折光差之值及其变化已被广泛应用。在某些测量实践中,对于测量过程及其以后的计算,必须事先给出折光差值。下面我们运用经验方法,以某地区一年期间的试验数据为基础来研究,求定垂直折光差角的可能性。确定垂直折光差的实验结果表明,它的     

高加索地震时地基振动的加速度谱

根据１９８８年１２月７日斯皮塔克地震和１９９１年４月２１日拉恰地震及其余震加速度图的分析,详细研究了这些地区在不同强度地震时,不同距离上地基振加速度频率的一些形成特点。建立了不同震级地震近场区的概率谱体系,确定了谱和对时间函数的估计,同加索不同震源区（达吉斯坦、普恰和斯皮塔克震中区）地基振动的概率步谱进行了对比分析。在预测加蕞大幅度反应谱的基础上以随机振频谱进行了对比分析。在预测加速度最大速度反应     

Study of blasting vibrations in Sarcheshmeh copper mine

Introduction In spite of development of mechanized methods of ground excavation, drilling and blasting is still extensively employed because of its low capital investment and simplicity. Its extensive use is not even limited by extension of mines close to residential areas and vital establishments. If it is not used in a controlled way, blasting operation can cause instability, failure of mine slopes and damps and damage to the nearby structures. The main objective here could be to reduce the …     

Who, when, and how? Marine planning stakeholder involvement preferences--a case study of the Solent, United Kingdom

The introduction of a marine planning system throughout English territorial waters over the next decade provides an opportunity for stakeholder input to the management of the marine environment. Stakeholder involvement has been identified as an important component of successful development and subsequent implementation of marine planning but it has to be recognised that the views and interest of stakeholders can vary greatly, thus the desire for involvement with the process is unlikely to be uniform. This paper presents the views of stakeholders within the Solent, United Kingdom on their potential involvement with the marine planning process. Interestingly, it highlights a strong variability of views within and across sectors. Assuming the situation in the Solent is typical of groups of stakeholders throughout the country, the lack of uniformity in the potential involvement from different stakeholders may present a challenge in achieving a representative and truly collaborative marine planning process.     

领域算法对震源特性之描述

对震源特性完整描述需要说明震源位置和震源机制。采用邻域算法经两个步骤就可实现非线形反演，邻域算法是一种参数空间中的直接搜索法，它能优先采集具最小数据拟合误差的区域，仅采用两个控制参数，无需导数计算。第一步是采用一个四维搜索空间的集中搜索方案来进行震源定位，第二步是对P和S波的早期波形反演来精确定位震源深度及提取源机制信息。这第二步就是采用一个矩张量表达式扫描一个八维空间。就震源和源机制反演而言，邻域算法（NA法）仅用几个测站的资料，就给出了快速有效的结果，正如对新疆南部一次事件处理所演示的一样。     

Use of total precipitable water classification of a priori error and quality control in atmospheric temperature and water vapor sounding retrieval

This study investigates the use of dynamic a priori error information according to atmospheric moistness and the use of quality controls in temperature and water vapor profile retrievals from hyperspectral infrared (IR) sounders. Temperature and water vapor profiles are retrieved from Atmospheric InfraRed Sounder (AIRS) radiance measurements by applying a physical iterative method using regression retrieval as the first guess. Based on the dependency of first-guess errors on the degree of atmospheric moistness, the a priori first-guess errors classified by total precipitable water (TPW) are applied in the AIRS physical retrieval procedure. Compared to the retrieval results from a fixed a priori error, boundary layer moisture retrievals appear to be improved via TPW classification of a priori first-guess errors. Six quality control (QC) tests, which check non-converged or bad retrievals, large residuals, high terrain and desert areas, and large temperature and moisture deviations from the first guess regression retrieval, are also applied in the AIRS physical retrievals. Significantly large errors are found for the retrievals rejected by these six QCs, and the retrieval errors are substantially reduced via QC over land, which suggest the usefulness and high impact of the QCs, especially over land. In conclusion, the use of dynamic a priori error information according to atmospheric moistness, and the use of appropriate QCs dealing with the geographical information and the deviation from the first-guess as well as the conventional inverse performance are suggested to improve temperature and moisture retrievals and their applications.