共查询到17条相似文献，搜索用时 625 毫秒
1.
外差激光雷达测量水体布里渊散射可行性研究 总被引：1，自引：0，他引：1
该文分析外差激光雷达测量水体布里渊散射的可行性。借助测量水体布里渊散射的频移 ,可得到水体声速或温度。文中利用两条 12 7I2 吸收线锁定激光输出频率 ,产生稳定的频差约为7.5 GHz发射激光和激光本振。通过对 12 7I2 吸收线稳定度、激光频率稳定度、系统信噪比和反演精度的分析和计算机模拟 ,得出水体深度 2 5 m以内水体布里渊散射频移的测量误差可以控制在2 .5 MHz以内 ,达到水中声速 0 .6 m/ s或温度 0 .1℃的测量精度。 相似文献
2.
文章从理论上分析了布里渊散射光的频移和强度与海水温度和应力的关系,针对分布式布里渊散射光纤传感器测量海水温度和压力的测量原理进行了论述,对该测量系统的构成以及测量的实现进行了探讨。 相似文献
3.
4.
模拟深海热液口环境(最高压力40 MPa,最高温度350℃),对深海热液区的主要成分CO2、CH4及其混合物的水溶液在不同压力和温度条件下的拉曼光谱进行探测和分析,结果显示:常温低压下CO2水溶液的Fermi双峰分别位于1 384.9 cm-1和1 278.3 cm-1处,CH4的水溶液拉曼峰υ1位于2 912.1 cm-1处,均比其气相的拉曼频移小;常温下CO2和CH4水溶液的拉曼特征峰随压力(≤40 MPa)的变化均不明显;在40 MPa的压力下随着温度的升高(≤350℃),CO2水溶液的Fermi双峰分别向高波数区移动了约3.4 cm-1和7.0 cm-1,而CH4水溶液的拉曼峰υ1向低波数区移动了约3.1cm-1;混合后升温过程中CO2的双峰分别向高波数区移动了约4.3 cm-1和3.8 cm-1,CH4的特征峰υ1向低波数区移动了4.5 cm-1。说明在室温到350℃范围内温度的变化对CO2和CH4水溶液拉曼频移有影响,频移量与温度线性相关,而压力在≤40 MPa范围内的改变对拉曼频移影响不明显。 相似文献
5.
基于相参X-波段海洋雷达的海表轮廓测量研究 总被引：4，自引：2，他引：2
X-波段海洋雷达测量所得海面散射单元的多普勒信息与散射单元的雷达视向速度密切相关。首先,基于符号多普勒估计方法,对X-波段雷达海面回波的多普勒频移信息进行了估计;在此基础上,应用各分辨单元回波的多普勒频移信息,建立了海浪表面轮廓的反演算法。该算法中,同时考虑了雷达入射角、方位角和雷达空间分辨率等因素对反演结果的影响。通过将反演结果与浮标测量数据相比较,发现雷达空间分辨率起到了类似低通滤波的作用,该作用对短重力波谱影响显著。同时,还应用加拿大麦克马斯特大学的IPIX雷达数据对海表轮廓进行了反演,并将反演所得有效波高、海浪周期与现场测量数据进行了比较,反演结果与现场测量结果吻合较好。 相似文献
6.
针对我国对海水温度剖面的测量需求,在分析已有方法优缺点的基础上提出了一种新的方法——光纤温度剖面连续测量系统.此测量系统以光纤光栅传感器为测量单元,采用波分复用的方式串接在一起组成船载拖曳链,再通过甲板上的解调终端实时显示所测物理参量,从而实现分布式实时测量.这种方法能够以低成本快速高效获得高分辨率的海水温度剖面分布情况,为海洋探测提供丰富有效的数据.课题组设计制作了拖曳链系统的甲板机及60 m长的拖曳链,并在青岛近海进行了拖曳海试,实时获取了试验数据,达到了预期效果. 相似文献
7.
在-2℃至35℃的整个海洋温度范围和0至42‰S盐度范围内测量准确已知盐度的海水样品电导率和同温度下标准海水电导率的比值R_(s.t.o)。盐度S<35‰的海水样品是由蒸馏水准确重量稀释标准海水制备的,快速蒸发标准海水制备高盐度海水样品继而重量稀释到已经确定的<35‰S范围。推导出了非常准确地表示1～42‰S和全部温度范围内的S与R_(s.t.o)关系式,即 S=f_1(R_(s.t.o)) f_2(R_(s.o,t.)t)=sum from n=0 to 5 a_1R~(a/2) △t/(1 k△t)sum from n=0 to 5 b_nR~(n/2)式中△t=t-15℃,R=R_(s.t.o),只有第一项f_1要求15℃。也确定了温度对标准海水电导率的影响,用t的四次方程非常准确地表示温度t时的电导率的比值的r_(tt)(C_(35.t.o)/C_(35.15.o)),即:(?)_t=sum from n=0 to 4 C_nt~n 这两个方程足以满足常压下所有盐度测量。 相似文献
8.
提出采用单模光纤作为XCTD的传输信道,首先对使用漆包线作为传输信道所面临的难题进行了简要的分析;其次,分析了单模光纤技术优势;最后,针对XCTD工作环境中海水温度变化对光纤传输信道带来的影响进行了理论研究和实验验证,实验结果表明,单模光纤信道在海水介质及0~20℃海温变化下,以10 MB/S的传输速率传输数据时误码率为0,且损耗变化几乎可以忽略,大大提高了信号传输的速率和传输稳定性,实验结果说明采用单模光纤作为XCTD的传输信道具有一定的可行性。 相似文献
9.
随着我国沿海地区海洋经济的快速发展,相关海域的风浪规律的研究越来越受到人们的重视。依据Toba的风浪3/2指数律和非线性频散关系推导得到一个新的波陡波龄关系式,简化获得适用于深水情况下的波陡波龄关系式;基于考虑非线性频散效应的波龄波陡深水关系式,并结合有效波能量平衡方程,进一步推导出包含非线性频散效应的深水海域风浪公式。利用新的深水风浪公式,并结合Mitsuyasu开阔海域风区、风速经验公式,研究了江苏沿海海域的风浪规律,且与NCEP再分析风浪数据以及其他公式结果进行对比分析。分析结果表明所获得的新深水风浪公式适用范围更广,且在只考虑风速这个单一参数条件下计算得到的江苏外海波浪要素与NCEP再分析风浪数据吻合程度最好,且更接近其他学者的研究成果。计算过程可避免开阔海域风区长度推算的不确定性和人为因素所产生的误差,可为我国风浪成长规律的理论研究和海洋工程深海风浪要素推算提供参考。 相似文献
10.
提出了一种基于双向Raman放大的Brillouin光时域分析系统(BOTDA).利用双向Raman抽运对信号光进行Raman放大以补偿光纤损耗及Brillouin抽运波的消耗,从而使光纤后端的测量分辨率得到改善,测量分辨率在整段传感光纤趋于一致,同时避免了调制不稳定性引起的频谱扩展,克服了传统BOTDA存在的信号强度指数下降的弊端,使传感精度得到进一步提高.实验实现了50 km传感距离, 温度分辨率达0.6 ℃,空间分辨率为50 m.测量并分析了基于双向Raman放大的BOTDA信噪比和光功率分布特性. 相似文献
11.
Brillouin light scattering technique can be successfully used to determine the whole set of elastic and piezoelectric constants of a ZnO single crystal irradiated by different laser energy densities, into a micron range (radiation layer thickness). It is found that the scattering intensity, the linewidth and the Brillouin scattering shift of acoustic phonons are all strongly dependent on laser energy density. Based on the sound propagation equations and these results, the directional dependences of the compressional and shear moduli of the irradiated ZnO sample in the (001) plane are investigated. It is found that under an appropriate laser condition, 248 nm KrF excimer laser irradiation can significantly improve the surface quality and increase the elastic properties of ZnO single crystal. This procedure has potential applications in the fabrication of ZnO-based surface acoustic wave and optic-electronic devices. 相似文献
12.
Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
13.
Derek V. Ellis 《Marine Georesources & Geotechnology》2001,19(1):51-63
This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested. 相似文献
14.
G. Parthiban 《Marine Georesources & Geotechnology》2000,18(3):223-235
Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement. 相似文献
15.
海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
16.
The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments. 相似文献
17.
Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献