地基GPS水汽遥测系统远程通讯与控制系统及其初步应用

地基GPS遥感大气水汽技术是20世纪90年代发展起来的一种全新的大气观测手段,建立科学合理的GPS数据实时采集通讯网,实时下载观测数据,可为地基GPS资料应用开发成果的业务化推广提供必要的技术支撑,是地基GPS大气水汽遥感系统可否推广应用的一项关键指标。介绍了采用Modem、依托公共电话网(PSTN)建立起来的远程数据通讯和控制系统。使用该系统可通过电话拨号的方式,对GPS水汽探测网内指定的GPS接收机的参数进行设置,还可以下载该接收机内存储的数据文件。该通讯系统的应用,增强了整个GPS遥感大气水汽探测网的可维护性,为最终实现GPS水汽探测网的业务化运行奠定了一定的理论和实践基础。针对该系统存在的数据下载速度慢,依赖人工操作等缺陷,提出了解决问题的思路。     

Removal of Aromatic Volatile Organic Compounds in the Sequencing Batch Reactor of Petroleum Refinery Wastewater Treatment Plant

This paper presents a field investigation of aromatic volatile organic compounds (AVOCs) emissions from a sequence batch reactor (SBR) with powdered activated carbon (PAC) to treat the wastewater in a large petroleum refinery plant. AVOC with high Henry's constant preferred to transfer from liquid‐phase into air‐phase so that might cause the emission and odor problem. During SBR operation, AVOC concentrations and distributions in wastewater, sludge and off‐gas were analyzed. The total AVOC removal from wastewater was >99% under the kinetic parameters of SBR operated. Batch experiments were carried out in the laboratory to obtain the adsorptive characteristic of AVOC onto PAC, but the results showed that bio‐degradation was the main removal mechanism (85%). Nevertheless, off‐gas emission (<1%) and AVOC in the sludge (<0.1%) remained a stable level. Oxidation/reduction potential (ORP) was correlated to the logarithm of the dissolved oxygen (DO) concentration in a linear relationship so that ORP profile could indirectly reflect the DO and biomass concentrations. Since the influent AVOC concentration was varied and difficultly to measure, ORP could be used as real‐time parameter for optimizing SBR operation. The results provided useful information for future evaluation of AVOC emissions from wastewater treatment plants.     

基于水华蓝藻固有光学特性的主要类群定量识别方法

蓝藻水华是湖泊水体富营养化的重要特征之一,不同水华蓝藻类群形成的水华特征、危害及其治理方法差异显著.因此,如何快速、准确地掌握不同蓝藻类群的时空分布特征成为实施富营养化湖泊污染治理与生态恢复、蓝藻生态灾害预测预警中一个亟待解决的科学问题.本研究基于纯藻种实验室培养和室内光学控制实验,在微囊藻(Microcystis)、鱼腥藻(Dolichospermum)、束丝藻(Aphanizomenon)3种主要水华蓝藻固有光学特性的基础上,通过甄别不同水华蓝藻的吸收、散射和后向散射光谱的特征波段,构建了基于吸收和散射特性的5种水华蓝藻类群的非线性最优化定量识别模型,其中,基于440、620和675 nm 3个波段吸收的a-CIM 440,620,675具有较为稳定的定量识别能力;并基于野外实测光学特性数据,实现了巢湖主要水华蓝藻类群的定量监测,初步分析了巢湖主要水华蓝藻类群的时空分布特性.研究表明,巢湖的水华蓝藻以鱼腥藻、微囊藻为主,束丝藻较少,鱼腥藻主要出现在温度较低的季节,微囊藻在夏季的西部湖区占优势;巢湖水华主要为微囊藻藻华和鱼腥藻藻华,且浓度较高的蓝藻主要存在于水体表面以下20 cm范围内;微囊藻和鱼腥藻在非藻华断面垂向上均匀分布.本研究可为富营养化湖泊蓝藻水华预测预警以及相关管理部门决策提供重要的理论依据和科学支撑.     

TOPEX/POSEIDON高度计浅海潮汐混淆的初步分析

根据对卫星轨道特征和观测结果的分析,对TOPEX/POSEIDON(简称T/P)星载高度计在我国近海的潮致混淆现象进行了初步研究.分析表明,在浅海区T/P高度计的观测结果存在很强的潮致高频混淆.NASA分发的地球物理记录中所提供的潮汐订正值虽适用于大洋,但不能有效地除去浅海潮汐.虽然如此,T/P潮致混淆的主要频段的周期小于90d,因而可以通过滤波方法提取周期较长的海面高度季节信号,从而用于季节环流(如南海季风环流)的研究.采用FFT/IFFT方法滤波试验的结果显示,T/P的海面高度观测结果有很高的精度,滤波处理后的海面高度距平变化和地面潮位观测结果一致性良好,上、下行轨道交叉处相邻测点间的标准偏差在3cm左右,可满足南海环流研究的需要.     

Evolving patterns of the fluids within the TAG hydrothermal field

The mixing of seawater/hydrothermal fluid within the large seafloor hydrothermal sulfide deposits plays a key role in the formation processes of the sulfide deposits. Some issues attract considerable attentions in the study of seafloor hydrothermal system in recent years, such as the relationships among different types of vent fluids, the characteristics of chemical compositions and mineral assemblages of the hydrothermal deposits and their governing factors. Combined with the measured data of hydrothermal fluid in the TAG field, the thermodynamic model of mixing processes of the heated seawater at different temperatures and the hydrothermal fluid is calculated to understand the precipitation mechanism of anhydrite and the genetic relationships between the black and white smoker fluids within the TAG mound. The results indicate that the heating of seawater and the mixing of hydrothermal fluid/seawater are largely responsible for anhydrite precipitation and the temperature of the heated seawater is not higher than 150°C and the temperature of the end-member hydrothermal fluid is not lower than 400°C. Based on the simulated results, the evolving patterns of fluids within the TAG deposit are discussed. The mixed fluid of the end-member hydrothermal fluid and the seawater heated by wall rock undergoes conductive cooling during upflowing within the deposit and forms “White Smoker” eventually. In addition, the end-member hydrothermal fluid without mixed with seawater, but undergoing conductive cooling, vents out of the deposit and forms “Black Smoker”. Supported by China Ocean Mineral Resources Research and Development Association Program (Grant No. DY115-02-1-01) and National Basic Research Program of China (Grant No. G2000078503)     

Study on the uncertainty of the available time under ship fire based on Monte Carlo sampling method

Available safety egress time under ship fire(SFAT) is critical to ship fire safety assessment,design and emergency rescue.Although it is available to determine SFAT by using fire models such as the two-zone fire model CFAST and the field model FDS,none of these models can address the uncertainties involved in the input parameters.To solve this problem,current study presents a framework of uncertainty analysis for SFAT.Firstly,a deterministic model estimating SFAT is built.The uncertainties of the input parameters are regarded as random variables with the given probability distribution functions.Subsequently,the deterministic SFAT model is employed to couple with a Monte Carlo sampling method to investigate the uncertainties of the SFAT.The Spearman’s rank-order correlation coefficient(SRCC) is used to examine the sensitivity of each input uncertainty parameter on SFAT.To illustrate the proposed approach in detail,a case study is performed.Based on the proposed approach,probability density function and cumulative density function of SFAT are obtained.Furthermore,sensitivity analysis with regard to SFAT is also conducted.The results give a high-negative correlation of SFAT and the fire growth coefficient whereas the effect of other parameters is so weak that they can be neglected.     

Peak earthquake response of structures under multi-component excitations

Accurate estimation of the peak seismic responses of structures is important in earthquake resistant design. The internal force distributions and the seismic responses of structures are quite complex, since ground motions are multi- directional. One key issue is the uncertainty of the incident angle between the directions of ground motion and the reference axes of the structure. Different assumed seismic incidences can result in different peak values within the scope of design spectrum analysis for a given structure and earthquake ground motion record combination. Using time history analysis to determine the maximum structural responses excited by a given earthquake record requires repetitive calculations to determine the critical incident angle. This paper presents a transformation approach for relatively accurate and rapid determination of the maximum peak responses of a linear structure subjected to three-dimensional excitations within all possible seismic incident angles. The responses can be deformations, internal forces, strains and so on. An irregular building structure model is established using SAP2000 program. Several typical earthquake records and an artifi cial white noise are applied to the structure model to illustrate the variation of the maximum structural responses for different incident angles. Numerical results show that for many structural parameters, the variation can be greater than 100%. This method can be directly applied to time history analysis of structures using existing computer software to determine the peak responses without carrying out the analyses for all possible incident angles. It can also be used to verify and/or modify aseismic designs by using response spectrum analysis.     

The eddy pair off eastern Vietnam: Interannual variability and impact on thermohaline structure

The main features, interannual variability of the eddy pair (an anti-cyclonic southern eddy and a cyclonic northern eddy) off eastern Vietnam and its impact on local thermohaline structure are analyzed using altimeter data, the Simple Ocean Data Assimilation (SODA) data, and the Medium-Range Weather Forecasts (ECWMF) data. The results show that the eddy pair is a seasonal phenomenon usually found in the summer to fall. It can reach downward to about 400 m depth but is strongest at the upper 100 m depth. In addition, the eddy pair displays a remarkable interannual variability with periods of 5.6 and 3.6 years. The local wind stress curl plays an important role in the interannual variability of eddy pair. Moreover, the eddy pair has an obvious impact on the thermohaline structure of the local upper ocean. The eddy pair can lead to stronger temperature variability in the upper 380 m but stronger salinity variability only in the upper 150 m depth. When the eddy pair is strong, the anti-cyclonic eddy deepens the thermocline, while the cyclonic eddy shoals the thermocline. Taking the depth of 20 °C isotherm as the thermocline depth, we find that in September, the thermocline drops downward to 110–140 m depth in the anti-cyclonic eddy but rises up to 50–80 m depth in the cyclonic eddy.     

内蒙古巴彦查干湖白云石的成因及其环境意义

对内蒙古南部巴彦查干湖12400cal.aB.P.以来的沉积物进行了X-衍射、扫描电镜、碳酸盐含量和自生碳酸盐氧同位素组成的研究。结果显示,沉积物中碳酸盐含量较高,6000cal.aB.P.以前为方解石,之后白云石开始出现,4800cal.aB.P.以来代替方解石成为主要的碳酸盐矿物。方解石的形态为细长的结晶棱柱体和薄片状,白云石颗粒的形态均为小球粒状,这些形态特征表明方解石和白云石是快速沉淀形成的。白云石的形态和大小与澳大利亚Coorong等地区微生物成因的白云石非常相似,表明巴彦查干湖白云石的形成可能与微生物活动有关。白云石在6000cal.aB.P.的出现是湖水咸化的直接证据,表明气候变干,这一结果与碳酸盐氧同位素和孢粉记录一致。     

全球气候变暖背景下登陆我国台风特征的分析

利用1949-2002年西北太平洋热带气旋、登陆我国台风和全球地面温度资料，对登陆我国台风的频数、强度以及登陆位置的年际变化，特别是趋势特征进行了分析，并与西北太平洋台风的变化特征作了对比。结果表明：在全球气候变暖背景下，我国登陆台风频数的减少趋势没有西北太平洋台风频数的减少趋势强；登陆台风的平均强度和极端强度均有减弱趋势，极端强度的减弱趋势尤为明显，但其强度弱于西北太平洋台风。在1968-2002年全球明显增暖时段，我国台风登陆位置偏向我国中部，西北太平洋台风在生命史中强度达最强时的位置有向北移动的趋势。