Hydrodynamic loads on subsea robots     

Carlos Rivera  Michael Hinchey 《Ocean Engineering》1999,26(8):589

Free floating subsea robots are often subjected to complex hydrodynamic loads due to waves/currents and wakes from nearby structures. This makes control extremely difficult. Good hydrodynamics data might counteract this. This paper presents hydrodynamics data for two configurations undergoing various combinations of steady translation and approximately steady rotation. The two configurations are: a spherical body with a single fixed link arm and a two link arm without a body. For both configurations neural networks were found to provide a reasonable fit to the data. We believe that such fits could be used to improve control.  相似文献   

硫酸盐热化学还原作用的启动机制研究   总被引：1，自引：0，他引：1  

张水昌  帅燕华  何坤  米敬奎 《岩石学报》2012,28(3):739-748

硫酸盐热化学还原作用(TSR)是导致高含硫化氢天然气生成和聚集、碳酸岩盐储层酸化和溶蚀的重要因素,是地质盆地内烃-水-岩三者之间的复杂反应。本文利用黄金管热模拟实验,对TSR反应的可能启动机制及控制因素进行了研究。通过不同盐溶液与原油的热解实验,证实了硫酸盐的存在是启动TSR反应的必要因素,MgSO4比CaSO4和Na2SO4更容易启动TSR反应,体系中盐度的增加会加速H2S的生成。实验结果表明,不同水介质条件下,TSR反应的程度与溶液的离子强度呈正相关,弱酸性环境并不足以启动TSR反应;原油中不稳定含硫化合物的含量越高越有利于TSR反应的发生,饱和链烷烃比原油中其它组分更容易引发TSR反应,且大分子烷烃比小分子烷烃更容易被硫酸盐氧化。  相似文献   

Testing and comparison of four ionic tracers to measure stream flow loss by multiple tracer injection     

Gary W. Zellweger 《水文研究》1994,8(2):155-165

The ionic tracers lithium, sodium, chloride and bromide were used to measure flow loss in a small stream (≈? 10 ls^?1). An injectate containing all four tracers was added continuously at five sites along a 507 m study reach of St Kevin Gulch, Lake County, Colorado to determine which sections of the stream were losing water to the stream bed and to ascertain how well the four tracers performed. The acidity of the stream (pH 3.6) made it possible for lithium and sodium, which are normally adsorbed by ion exchange with stream bed sediment, to be used as conservative tracers. Net flow losses as low as 0.8 ls^?1, or 8% of flow, were calculated between measuring sites. By comparing the results of simultaneous injection it was determined whether subsections of the study reach were influent or effluent. Evaluation of tracer concentrations along 116 m of stream indicated that all four tracers behaved conservatively. Discharges measured by Parshall flumes were 4–18% greater than discharges measured by tracer dilution.  相似文献   

Tracer release in melting snow: Diurnal and seasonal patterns     

Roger C. Bales  Robert E. Davis  Mark W. Williams 《水文研究》1993,7(4):389-401

Time sequences of tracer release from an alpine snowpack were investigated at Mammoth Mountain, California in 1989. Lysimeter discharge and conductivity were recorded at 30 minute intervals. Three separate applications of chemical tracers were added to the snow surface to provide an ionic signal with known origins in the snowpack. Grab samples of meltwater and snow from snow pits were analysed for chemical composition. There were three distinct discharge periods, each characterized by diurnal fluctuations in discharge and conductivity. An inverse relation between discharge and conductivity was interpreted as the combination of a concentrated signal from regions in the pack less subject to leaching and a relatively dilute signal from near the snow surface where the snow was actively melting Conductivity peaks were highest and diurnal changes greatest immediately following periods of freezing. Grab samples showed little correlation with either 30 minute or daily average conductivity. Relative concentrations of individual ions in meltwater were similar between samples. Non-systematic grab sampling of snowpack meltwater is shown to be potentially misleading because of multiple ionic pulses over the ablation season and strong diurnal fluctuations in chemical concentrations. Continuous measurements of discharge conductivity are a good indicator of diurnal and seasonal changes in the rate of ion release from the snowpack, and should be used to guide sampling. Composite, or time-integrated samples rather than grab samples may be required to estimate daily and weekly rates of ion release in melting snow.  相似文献   

Synthesis of Multiwalled Carbon Nanotube Modified BiOCl Microspheres with Enhanced Visible‐Light Response Photoactivity          下载免费PDF全文

Jun Di  Ming Li  Wenmin Fan  Jiexiang Xia  Hui Xu  Yilin Sun  Huaming Li 《洁净——土壤、空气、水》2016,44(7):781-787

  相似文献   

Ionic Liquid Modified Resin for the Adsorptive Removal of Dibutyl Phthalate: Equilibrium,Kinetic, and Thermodynamic Studies     

Umair A. Qureshi  Amber R. Solangi  Saima Q. Memon  Syed I. H. Taqvi  Najma Memon 《洁净——土壤、空气、水》2012,40(6):630-639

This study evaluated the adsorptive properties of dibutyl phthalate (DBP) on room temperature ionic liquid (RTIL) modified XAD‐4 resin. The modified RTIL‐XAD 4 sorbent was characterized by FTIR. Effect of varying experimental conditions such as pH, contact time, temperature, shaking speed, concentrations, and interfering species were investigated by batch adsorption experiments. Adsorption was found to be most favorable at pH 6 within 30 min. Experimental data were evaluated in terms of kinetic, equilibrium, and thermodynamic modeling. Kinetics of the sorption was found to follow pseudo second order rate equation whereas Freundlich and D–R isotherms were the most suitable models to explain sorption phenomenon. Thermodynamically sorption was endothermic, irreversible, and spontaneous in nature.  相似文献   

乌鲁木齐市不同天气条件下TSP水溶性离子特征分析   总被引：3，自引：0，他引：3  

刘新春 《沙漠与绿洲气象(新疆气象)》2012,6(5):60-66

利用2009年乌鲁木齐4个大气总悬浮颗粒物（TSP）观测站点样品,采用离子色谱仪测定了不同天气条件下TSP中水溶性离子成分,分析了水溶性离子变化特征及影响因素,结果表明：不同天气条件对乌鲁木齐市TSP中的NH4 、Ca2 、NO3-和SO42-浓度具有明显的影响。降水对离子有清除作用,使其在TSP中浓度减小。大风及沙尘天气使TSP中Ca2 浓度大幅增加,其它离子增加幅度很小。连续污染日,各离子在大气中累积至较高浓度,是同期晴天条件下的2-7倍。气象因素对采暖期TSP离子浓度变化影响较大。非采暖期乌鲁木齐市TSP离子浓度主要受到自然因素引起的土壤尘和建筑尘的影响。  相似文献   

Pb、Sr和REE在矿物中的扩散补偿关系及其对扩散系数的预测   总被引：4，自引：2，他引：4  

赵子福  郑永飞 《岩石学报》2001,17(1):69-94

对现有实验扩散数据的检查发现，不仅Pb、Sr和REE元素在不同矿物中存在着扩散补偿关系，不同元素在同一矿物或同族矿物中也满足扩散补偿关系。阴离子孔隙度作为矿物内部离子堆积密度的一种量度，它与Pb和REE扩散活化能之间存在负的线性相关性，在固定温度下与Sr扩散系数（lnDT)之间呈正的线性相关，因而可以用于预测元素在矿物中的扩散系数。本文分别采用离子孔隙度法和双补偿法预测了Pb、Sr和REE在不同矿物中的扩散系数，这些结果与已有的实验数据在实验误差范围内是一致的，因此可以应用到与扩散有关的地球化学动力学研究中。  相似文献   

稀散金属化合物热力学性质的研究Ⅱ:HCl-In2(SO4)3-H2O体系          下载免费PDF全文

王琴萍  吕殿祯  张丽  孙雪丽  杨家振 《盐湖研究》2003,11(1):14-20

在HCl In2 (SO4) 3 H2 O体系中 ,溶液表观总离子强度恒定为I=0 2、0 4、0 6、0 8、1 0、1 5mol·kg-1,硫酸铟在溶液中的表观离子强度分数恒定为yB =0 0 0、0 1 0、0 2 0、0 3 0、0 5 0和 0 70条件下 ,应用经典的电动势方法测定无液体接界电池 (A)在 2 78 1 5～ 3 1 8 1 5K温度范围内的电动势 :Pt,H2 (1 0 1 3 2 5kPa) |HCl(mA) ,In2 (SO4) 3 (mB) ,H2 O|AgCl Ag (A)根据测得电池 (A)的电动势数据 ,考虑到该体系存在硫酸的二级解离 ,应用数学迭代方法确定平衡体系氢离子的浓度 ,进而确定了混合溶液中HCl的活度系数γA。结果表明 ,HCl的活度系数服从扩展的Harned规则。  相似文献   

2003年夏季临安地区大气气溶胶离子成分的尺度分布特征   总被引：16，自引：0，他引：16  

颜鹏  张养梅  杨东贞  汤洁  于晓岚  程红兵  俞向明 《气象学报》2005,63(6):980-987

文中利用2003年夏季在浙江临安大气本底污染监测站观测的资料,分析了临安的气溶胶质量浓度、离子成分的尺度分布特点及主要离子间的相互关系。初步结果显示,该期间临安气溶胶主要以粒径小于2.1μm的细粒子为主,约占总质量浓度的66%,其中粒径小于0.65μm的粒子可达总质量浓度的50%,远高于其他各级尺度段上的粒子浓度。与质量浓度分布相似,可溶性无机离子成分主要集中在粒径小于2.1μm(记为PM2.1)的细粒子中,PM2.1粒子中可溶性无机离子约占所有尺度段(包括所有5级)离子质量浓度总和的88%。其中粒径小于0.65μm的亚微米粒子中的离子质量浓度是细粒子的主要部分,占所有尺度段上离子质量浓度总和的77%。SO42-,NH4+和K+是PM2.1中决定性的离子成分。相关分析和离子平衡表明,PM2.1中SO42-与NH4+和K+有很高的相关,在粒径小于0.65μm的亚微米粒子中,非海盐硫酸盐(Nss-SO42-)主要为(NH4)2SO4,由气-粒转化产生;而在粒径为0.65~2.1μm尺度段,Nss-SO42-除(NH4)2SO4外,可能还有K2SO4,Na2SO4等存在。  相似文献