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41.
GW112AD型水下监视系统是携带方便、结构新颖、功能齐全和图像清晰的一款水下监视装置,通过对三号地井下环境进行检查发现,井管腐蚀老化,淤泥堵塞现象较严重,对水位变化影响较大,三号地水位多次突降异常的信度一般,需对该井进行必要的洗井清理工作. 相似文献
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Origin of the fumarolic fluids of Vulcano Island,Italy and implications for volcanic surveillance 总被引:2,自引:2,他引:0
Variations in D and 18O values with H2O contents and outlet temperatures indicate that the fumaroles of La Fossa crater have discharged mixtures of magmatic water and marine hydrothermal water, since 1979. The contribution of meteoric water was low in the period 1979–1982 and very low afterwards. The 18O values of the marine-hydrothermal component of +5 to +7.2 are due to isotopic exchange with the 18O-rich silicates of the rocks under high-temperature and low-permeability conditions. The 18O value of the magmatic end-member is generally +3.5 to +4.3, although values as high as +5.5 to +6.5 were reached in the summer of 1988, when magma degassing appears to have extended into the core of the magma body. The D values of the end-member were close to -20, typical of andesitic waters. Both the isotopic values and chemical data strongly support a dry model, consisting of a central magmatic gas column and a surrounding hydrothermal envelope, in which marine hydrothermal brines move along limited fracture zones to undergo total evaporation on approaching the conduits of magmatic fluids. The vents at the eastern and western boundaries of the fumarolic field are fed by fluids whose pressure is governed by the coexistence of vapor, liquid and halite, giving rise to a high risk of phreato magmatic explosions, should magma penetrate into these wet environments. Most La Fossa eruptions were triggered by an initial hydrothermal blast and continued with a series of phreatomagmatic explosions. The fluids discharged by the Forgia Vecchia fumaroles are mixed with meteoric water, which is largely evaporated, although subordinate loss of condensed steam may be responsible for scrubbing most of the acidic gas species. The temperatures and pressures, and the risk of a sudden pressure increase, are low. A boiling hydrothermal aquifer at 230° C is present underneath the Baia di Levante beach. This area has a minor risk of hydrothermal explosions. 相似文献
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针对近些年图像质量评价的重要性,提出一种针对道路监控视频的图像质量评估方法。因为道路监控视频具有连贯性、图像稳定性强、单个监控视频场景单一等特点,本文采用一种结合多幅图像创建物理模型对比恢复天气影响的图像质量评估方法,通过多幅图像比较恢复道路视频图像清晰度,加入噪声亮度比的因子来增加图像的鲁棒性和准确性,分析该方法的优势和不足。 相似文献
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Compared with solution ICP‐MS, LA‐ICP‐MS studies have thus far reported comparatively few external reference data for accuracy estimates of experiments. This is largely the result of a paucity of available reference materials of natural composition. Here, we report an evaluation of natural glass (obsidian) as an inexpensive and widely available external reference material. The homogeneity of over forty elements in six different obsidian samples was assessed by LA‐ICP‐MS. Accuracy was tested with two obsidian samples that were fully characterised by electron probe microanalysis and solution ICP‐MS. Laser ablation experiments were performed with a variety of ablation parameters (fluence, spot sizes, ablation repetition rates) and calibration approaches (natural vs. synthetic reference materials, and different internal standard elements) to determine the best practice for obsidian analysis. Furthermore, the samples were analysed using two different laser wavelengths (193 nm and 213 nm) to compare the effect of potential ablation‐related phenomena (e.g., fractionation). Our data indicate that ablation with fluences larger than 6 J cm?2 and repetition rates of 5 or 10 Hz resulted in the most accurate results. Furthermore, synthetic NIST SRM 611 and 612 glasses worked better as reference materials compared with lower SiO2 content reference materials (e.g., BHVO‐2G or GOR128‐G). The very similar SiO2 content of the NIST SRM glasses and obsidian (i.e., matrix and compositional match) seems to be the first‐order control on the ablation behaviour and, hence, the accuracy of the data. The use of different internal standard elements for the quantification of the obsidian data showed that Si and Na yielded accurate results for most elements. Nevertheless, for the analysis of samples with high SiO2 concentrations, it is recommended to use Si as the internal standard because it can be more precisely determined by electron probe microanalysis. At the scale of typical LA analyses, the six obsidian samples proved to be surprisingly homogenous. Analyses with a spot size of 80 μm resulted in relative standard deviations (% RSD) better than 8% for all but the most depleted elements (e.g., Sc, V, Ni, Cr, Cu, Cd) in these evolved glasses. The combined characteristics render obsidian a suitable, inexpensive and widely available, external quality‐control material in LA‐ICP‐MS analysis for many applications. Moreover, obsidian glass is suited for tuning purposes, and well‐characterised obsidian could even be used as a matrix‐matched reference material for a considerable number of elements in studies of samples with high SiO2 contents. 相似文献
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《Marine Policy》2014
As catch and effort statistics including fishing time and location are essential for producing abundance indices for utilized fish stocks, fishing states are encouraged under the FAO Code of Conduct for Responsible Fisheries to collect and maintain such statistics. However, for coastal fisheries (including artisanal fisheries) that are mainly composed of small-sized vessels which are usually too numerous to monitor, fisheries statistics collection systems are often either lacking or of insufficient quality (e.g. incomplete or inaccurate). Vessel monitoring system (VMS) data are commonly used to construct or improve estimation of fishing effort and fishing location in large-scale fisheries. Most coastal fisheries lack VMS but their countries do have coastal surveillance radar systems (CSRS) for security and enforcement purposes. This study illustrates and recommends opportunistic use of CSRS data to provide similar scientific benefits to VMS data for coastal fisheries. CSRS in combination with market landings data can construct logbook-like catch and effort statistics. This study introduces a method and demonstrates its usefulness for scientific research and management purposes, including the potential to obtain a higher accuracy and precision, particularly for fishing location and catch amount. Limitations of the CSRS data and challenges to managers involved in its application are also discussed. 相似文献
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针对动态目标检测中的图像背景实时提取问题,采用红绿蓝三分量综合考虑的方法,进行了比较深入的算法研究。研究表明,如果图像序列时间段过短,背景中就会有目标空洞,如果图像序列时间段过长,则不能反映实时背景,在后续目标检测中就会引起较大误差。考虑合理的视频场景区域的动态目标密集程度因素,就可以较好地兼顾提取背景的实时性和背景中目标空洞的消除。 相似文献
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本文立足于烟台市海域使用动态监视监测实际情况,通过分析航空遥感在海域动态监管工作中的优缺点,将航空遥感技术应用于海域使用动态监测中。监测结果表明:航空遥感可以实现海域空间资源监测、区域建设用海规划监测和重点项目监测等海域使用动态监测,可以满足海域动态监管的各类型监视监测工作要求。 相似文献