排序方式： 共有23条查询结果，搜索用时 15 毫秒
1.
L. A. Morgan W. C. Shanks III D. A. Lovalvo S. Y. Johnson W. J. Stephenson K. L. Pierce S. S. Harlan C. A. Finn G. Lee M. Webring B. Schulze J. Dühn R. Sweeney L. Balistrieri 《Journal of Volcanology and Geothermal Research》2003,122(3-4):221-242
‘No portion of the American continent is perhaps so rich in wonders as the Yellow Stone’ (F.V. Hayden, September 2, 1874)Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (1–200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem. 相似文献
2.
The advantages of using unmanned underwater vehicles in coastal ocean studies are emphasized. Two types of representative vehicles, remotely operated vehicle (ROV) and autonomous underwater vehicle (AUV) from University of South Florida, are discussed. Two individual modular sensor packages designed and tested for these platforms and field measurement results are also presented. The bottom classification and albedo package, BCAP, provides fast and accurate estimates of bottom albedos, along with other parameters such as in-water remote sensing reflectance. The real-time ocean bottom optical topographer, ROBOT, reveals high-resolution 3-dimentional bottom topography for target identification. Field data and results from recent Coastal Benthic Optical Properties field campaign, 1999 and 2000, are presented. Advantages and limitations of these vehicles and applications of modular sensor packages are compared and discussed. 相似文献
3.
Parameter identification of a remotely operated vehicle (ROV) is often based on the dynamic responses collected by its onboard sensors. However, for commercial ROVs, the required data for identification may not be available due to the absence of suitable sensors or limitations in accessing onboard sensor data. Therefore, this study proposes a vision-based tracking system to measure the dynamic response of an ROV. The tracking system is independent of the ROV, and is able to localize an ROV to a high degree of precision by means of projective mapping. The validity of the proposed tracking system is demonstrated through identification of a commercial ROV. A simplified nonlinear ROV dynamic model with six degrees of freedom (DOF) is used for identification. Uncoupled motions, including surge, sway, and yaw, are obtained from the ROV dynamic model, and the corresponding experiments are carried out for each DOF. Hydrodynamic parameters are then estimated with numerical optimizations by comparing the measured ROV responses with the output of the mathematical model. The experimental results show that the vision-based tracking system can accurately measure the transient and steady-state responses of an ROV. Additionally, the simulations of the ROV dynamic model, with the optimal parameter estimates, give results in agreement with the measured data. 相似文献
4.
《African Journal of Marine Science》2013,35(2):215-222
Remotely operated vehicle (ROV) video observations were used to document benthic fauna at a hydrocarbon drilling location, at 2 720 m depth, in the poorly studied deep water off northern Egypt. The decapod Chaceon mediterraneus was the most common organism at the site and the only benthic megafaunal invertebrate observed. Three species of fish, Coryphaenoides mediterraneus, Cataetyx laticeps and Bathypterois mediterraneus, were also encountered. These findings confirmed these three species as the deepest-distributed benthic fish in the eastern Mediterranean, and confirmed that the deep Mediterranean, in particular the eastern basin, is one of the world's poorest deep-sea ecosystems in terms of diversity. The behaviour exhibited by the species observed was consistent with their natatory capacity, deduced from their feeding intensity (gut fullness) and diet (mainly suprabenthic prey were consumed), and conservative life strategies adapted to an extremely low energy environment. 相似文献
5.
研究有缆遥控潜水器(Remote Operated Vehicles)的脐带缆受到轴向激励所产生的大幅横向振动,即参量共振.ROV脐带缆的参激现象发生会影响ROV的安全性.针对ROV脐带缆的结构特性,推导出其在轴向激励力下的非线性振动方程.运用希尔无穷行列式的方法分析脐带缆的参量不稳定性.以稳定性图为基准分析脐带缆在多... 相似文献
6.
On the motions of the underwater remotely operated vehicle with the umbilical cable effect 总被引：1，自引：0，他引：1
In this paper, a hydrodynamic model is developed to simulate the six degrees of freedom motions of the underwater remotely operated vehicle (ROV) including the umbilical cable effect. The corresponding hydrodynamic forces on the underwater vehicle are obtained by the planar motion mechanism test technique. With the relevant hydrodynamic coefficients, the 4th-order Runge–Kutta numerical method is then adopted to solve the equations of motions of the ROV and the configuration of the umbilical cable. The multi-step shooting method is also suggested to solve the two-end boundary-value problem on the umbilical cable with respect to a set of first-order ordinary differential equation system. All operation simulations for the ROV including forward moving, ascending, descending, sideward moving and turning motions can be analyzed, either with or without umbilical cable effect. The current effect is also taken into consideration. The present results reveal that the umbilical cable indeed significantly affects the motion of the ROV and should not be neglected in the simulation. 相似文献
7.
As the soil traction of the track system consisting of a track plate and protruded grousers is generally higher than that of a comparable wheel system, underwater tracked vehicles are the favored platforms for heavy-weight remotely operated vehicles (ROVs). When an underwater tracked vehicle moves on the seafloor, the track system laterally transmits an engine torque to the soil-track interface, resulting in slip displacement and an associated soil thrust acting as a traction force. Therefore, to evaluate the mobility of underwater tracked vehicle, it is critical to evaluate the soil thrust of the track system based on the soil-track interaction. Unlike the soil thrust of sandy soils, a reliable soil thrust assessment method accounting for the failure mechanism of clayey soil has yet to be developed in spite of its significance. An experimental study on the mechanism of the soil thrust of clayey soil was thus performed. Model track experiments were conducted on a model track system with clayey soil. Based on the experiment results, the mechanism of the soil thrust of clayey soil was investigated and was compared with the mechanism of soil thrust derived from the previous soil thrust assessment methods using sandy soil. Particular attention was given to the development of a new soil thrust prediction model for the track system on clayey soil using the limit equilibrium analysis technique. 相似文献
8.
MK—2型全液压坑道钻机 总被引：1，自引：0，他引：1
ＭＫ—２型全液压坑道钻机为一种轻便的井下浅孔钻凿设备,是吸取国外先进钻机优点并结合国内实际情况研制而成的,主要用于井下瓦斯抽放、超前探测及煤体注水的施工作业。本文介绍了该钻机的结构、技术参数和工业性试验情况。 相似文献
9.
GDROV是用于堤坝探测的水下机器人,设计上属于开架式机器人,其精确的数学模型很难获得.采用基于模糊逻辑的直接自适应控制方法,利用模糊基函数网络逼近理想控制输出,通过模糊逻辑动态调整控制器的参数自适应律,可有效解决水下机器人控制问题.建立GDROV的水动力模型,给出基于模糊逻辑的直接自适应控制算法,最后通过仿真试验和外场试验验证了该控制器对模型的不确定性具有较强的鲁棒性,且具有良好的跟踪性能. 相似文献
10.
连霍高速不同运营路段路旁土壤重金属分布及潜在生态风险 总被引：7，自引：0，他引：7
在连霍高速公路运营时间不同的湾刘和小王庄断面, 按照距离公路的远近不同布设采样点, 对路旁土壤重金属(Cd、Cu、Pb、Zn、Ni、Cr)的空间分布特征及土壤重金属潜在生态风险展开研究。结果表明:运营时间较长的湾刘断面(处于中等生态风险状态)路旁土壤重金属含量高于小王庄断面(总体处于轻微生态风险状态)。随着距公路路基距离的增加, 多数重金属含量及潜在生态风险呈不规则偏态分布。湾刘断面的RI峰值出现在距路基50～100m之间, 小王庄断面出现在距路基35 m处。土壤Cd是最主要的风险因子, 对RI的贡献率平均为61.39%。土壤污染物潜在生态风险评价应根据所研究污染物种类和数量对H?kanson 潜在生态风险指数分级标准进行适当调整。 相似文献