Variability of organic δC and C/N in the Mersey Estuary, U.K. and its implications for sea-level reconstruction studies

Microfossil analysis (e.g. diatoms, foraminifera and pollen) represents the cornerstone of Holocene relative sea-level (RSL) reconstruction because their distribution in the contemporary inter-tidal zone is principally controlled by ground elevation within the tidal frame. A combination of poor microfossil preservation and a limited range in the sediment record may severely restrict the accuracy of resulting RSL reconstructions. Organic δ¹³C and C/N analysis of inter-tidal sediments have shown some potential as coastal palaeoenvironmental proxies. Here we assess their viability for reconstructing RSL change by examining patterns of organic δ¹³C and C/N values in a modern estuarine environment. δ¹³C and C/N analysis of bulk organic inter-tidal sediments and vegetation, as well as suspended and bedload organic sediments of the Mersey Estuary, U.K., demonstrate that the two main sources of organic carbon to surface saltmarsh sediments (terrestrial vegetation and tidal-derived particulate organic matter) have distinctive δ¹³C and C/N signatures. The resulting relationship between ground elevation within the tidal frame and surface sediment δ¹³C and C/N is unaffected by decompositional changes. The potential of this technique for RSL reconstruction is demonstrated by the analysis of part of an early Holocene sediment core from the Mersey Estuary. Organic δ¹³C and C/N analysis is less time consuming than microfossil analysis and is likely to provide continuous records of RSL change.     

甚高频电磁波多参数层析成像技术及其应用研究

电磁波速度或衰减层析成像技术单独用于岩溶勘察存在多解性缺陷,降低了应用的准确性.基于电阻率和相对介电常数直接反映溶洞与周围介质存在的电性差异,以电磁波速度和衰减层析成像理论为基础,提出了电阻率和相对介电常数层析成像理论,并应用于实例工程.通过对其电磁波速度、衰减、相对介电常数、电阻率4参数层析成像结果进行对比分析和钻探验证,证明了基于电磁波的电阻率和相对介电常数层析成像技术是可行的,形成了电磁波速度、衰减、相对介电常数、电阻率多参数层析成像综合分析方法,提高了电磁波层析成像技术探测溶洞及其充填情况的准确性.     

空间合作目标交会对接光学测量研究

随着人类探索太空活动的深入,空间交会对接技术(RVD)发挥着越来越重要的作用。本文在介绍国外交会对接测量技术最新研究现状的基础上,研究了交会对接光学成像测量系统的原理和测量算法,并分析了光学成像测量系统设计中的几个关键技术,其测量有效性和测量精度直接关系到交会对接任务的成功与否,最后讨论了未来交会对接技术的发展方向。     

基于增强型GPS的自适应UKF实时星间相对定位方法

高精度的星间实时相对定位是卫星编队飞行的一项关键技术。本文以双星编队为例,提出一种基于GPS双频P码、双频载波相位以及星间距离观测信息的自适应UKF、实时相对定位方法。仿真结果表明:相比传统的EKF方法,该算法能有效地提高滤波稳定性及相对定位精度,而且,星间测距信息的引入能大大减少整周模糊度判定所需的历元数。     

关于海平面上升及其环境效应

沿海地区地质环境复杂。由于国民经济的迅速发展,人类活动日益增多,对地质环境进一步造成严重的不利影响。特别是“温室效应”引发的海平面上升,使各种地质灾害更加激化。文章详细探讨了海平面上升的影响因素,理论海平面与相对海平面升降幅度的评估,以及海平面上升所造成的地质环境效应与相应的防治对策,特别强调控制沿海城市地面沉降,以减轻海平面相对上升造成的危害,具有特殊而重要的意义。     

The relationship between zooplankton,conductivity and lake-water ionic composition in 111 lakes from the Interior Plateau of British Columbia,Canada

Zooplankton collected from vertical net tows were related to the environmental variables from 98 lakes from the Interior Plateau of British Columbia. Canonical correspondence analysis showed that both salinity and ionic composition (pH and Mg) of the lake-water made major and significant contributions to the first two ordination axes (=0.42 and 0.11 respectively,P<0.05). BothArtemia franciscana andMoina hutchinsoni had their highest relative abundance in meso-hypersaline waters. However,Artemia franciscana preferred waters that were higher in Mg and Ca, whileMoina hutchinsoni was found in waters that were lower in Mg and Ca. Similarly, at intermediate salinities,Daphnia pulex and the calanoid copepods preferred waters slightly lower in Mg and Ca, whereasCeriodaphnia laticaudata andSimocephalus spp. were relatively more common in waters higher in Mg and Ca. Because the freshest lakes studied varied much less in ionic composition, the zooplankton in these lakes did not show a preference to ionic composition. As expected, multi-generic groups, such as the calanoid copepods, cyclopoid copepods and nauplii, had wider tolerances to conductivity than groups identified to lower taxonomic levels. Significant weighted-averaging regression and calibration models of conductivity were developed based on zooplankton species composition from the study lakes (r ²=0.56,P<0.05). Samples composed largely of multi-generic taxa yielded the worst estimates of salinity in the reconstruction model. This study suggests that zooplankton community composition may be developed into a useful proxy for paleosalinity reconstruction.     

非加温型四连栋塑料温室内外温湿度关系研究

根据1999年12月～2002年8月典型天气（晴天、多云、阴天）下非加温型四连栋塑料温室中间1．5m高度气温、相对湿度的观测数据，应用逐步回归分析方法建立了冬季、春秋季、夏季典型天气下温室内日平均气温、日最高气温、日最低气温、日平均相对湿度与气象站气象要素间的关系式，为温室蔬菜品种筛选、蔬菜标准化栽培、无公害蔬菜生产和病虫害防治提供小气候方面的技术数据。     

相对湿度对静电收集型连续测氡仪检定结果的影响

NR－667A（Ⅲ）型快速连续测氧仪是目前环境氡测量时间响应最短的一种仪器。该仪器在核工业第六研究所标准氡室进行检定时发现，环境相对相对度对仪器检定结果有很大影响。在相对湿度为80％－99％的标准氡室内分别对仪器进行检定，结果在相对湿度为80％时仪器检定合格，而在相对湿度为99％时仪器检定不合格。本从仪器工作原理对检定结果进行。并提出有效的解决方法，当相对湿度太大时，可在仪器进气口安装干燥器对进气进行除湿。     

桥梁限位器抗震设计方法研究

本文建立了两跨简支梁桥和五跨多跨刚架桥两结构模型，针对限位器的种类、刚度、强度、安装位置，输入地震动等进行了大量工况下的数值模拟研究。研究表明限位器与柱（框架）的刚度比在0.5-2之间较优。将现有的限位器设计方法应用于两算例结构，对现有限位器设计方法进行了比较研究。     

改进的最小二乘法在水文分析计算中的应用

在水分析计算中，经常涉及到变量之间的线性或非线性拟合，而在拟合各种特性曲线时，通常应用以实测资料与拟合曲线间的误差平方和最小作为目标函数的方法——最小二乘法，但这种方法忽视了所有实测点应与拟合曲线间的相对误差尽量不超过某一百分比的原则，为了达到上述要求，提出了非线性的加权最小二乘法及线性相关方程的最小距离平方和法，探讨改进了传统的最小二乘法达到优化的效果。最小距离平方和法与常用的图解法相比，本法所得成果较为客观；与传统的单方向(x或y方向)最小二乘回归法相比，所求线性方程不会因坐标系的选取而改变。最后应用算例进行了初步讨论。