Study on visual control system of acoustic in situ measurement technology for survey of seafloor sediment

Abstract

A new kind of visual acoustic measurement system was developed to obtain the acoustic characteristics of seabed sediment and the working state of in situ measuring equipment in real time. The control unit of the system structure is mainly made up of the underwater control unit and the deck control unit. In comparison with similar traditional systems, the system can transmit the working video image, the measured acoustic data and the waveform synchronous from the underwater control equipment to the deck control unit through the connecting cable. Apart from self-contained in situ measurement, the working modes of it include visual online real-time control. In order to guarantee the stability and measurement precision of the video control system, the process control of in situ measurement was strictly tested in the experimental tank. In 2017, sea trials of the in situ measurement system was carried out in the South China Sea. In the process, data related to measurement, including the acoustic velocity and attenuation coefficient of the seabed sediment, were obtained as well. The results from sea trials show that the control process of the visual system is intuitive, reliable and accurate, and therefore it can be popularized and applied.     

Effects of the undecomposed layer and semi-decomposed layer of Quercus variabilis litter on the soil erosion process and the eroded sediment particle size distribution

Simulated rainfall experiments were performed on bare, undecomposed litter layer and semi-decomposed litter layer slopes with litter biomasses of 0, 50, 100 and 150 g m⁻², respectively, to evaluate the effect of the undecomposed layer and semi-decomposed layer of Quercus variabilis litter on the soil erosion process and the particle size distribution of eroded sediment. The undecomposed layer and semi-decomposed layer of litter reduced the runoff rate by 10.91–27.04% and 12.91–36.05%, respectively, and the erosion rate by 13.35–40.98% and 17.16–59.46%, respectively. The percentage of smaller particles (clay and fine silt particles) decreased and the percentage of larger particles (coarse silt and sand particles) increased with an increased rainfall duration on all treated slopes, while the extent of the eroded sediment particle content varied among the treated slopes with the rainfall duration, with bare slopes exhibiting the largest variability, followed by undecomposed litter layer slopes and finally semi-decomposed litter layer slopes. The clay and sand particles were transported as aggregates, and fine silt and coarse silt particles were transported as primary particles. Compared with the original soil, sediment eroded from all treated slopes was mainly enriched in smaller particles. Furthermore, the loss of the smaller particles from the undecomposed litter layer slopes was lower than that from the semi-decomposed litter layer slopes, indicating that the undecomposed litter layer alleviated soil coarsening to some extent. The findings from this study improve our understanding of how litter regulates slope erosion and provide a reference for effectively controlling soil erosion.     

Failure Mechanism and Control of Surrounding Rock of Mining Roadway Under Overlying Goaf

Geotechnical and Geological Engineering - Aiming at the deformation and failure of roadway surrounding rock and its control problems under goaf in upper and lower coal seam mining of Buertai Coal...     

3D geological architecture and ore -controlling structures of the Paomaping Zn-Pb deposit at the Jinding ore field,Lanping County,SE Tibetan PlateauSCIEI北大核心CSCD

滇西北金顶超大型铅锌矿田位于青藏高原东南缘兰坪中-新生代盆地中部,是三江成矿带中南段最典型的密西西比河谷型(MVT)矿床之一,其构造控矿和盆地流体成矿特征明显受控于印度-欧亚大陆碰撞有关的区域挤压构造。近年来,矿床浅部地质条件与资源状况已被充分揭露,但其深部地质结构、构造控矿差异性仍不清楚,这也制约了成矿预测和找矿新发现。本文以矿田东北部的跑马坪大型隐伏矿床为研究对象,利用三维地质建模及空间分析方法,识别矿化空间变化及其与断层、不整合面和地层岩性的配置关系,分析构造控矿规律及可能的流体运聚趋势。结果表明,跑马坪铅锌矿床的成矿作用与近E-W向挤压构造对中新统金顶砂泥岩(Mio-j)与上三叠统三合洞组(T_(3)s)不整合面的差异性破坏关系密切,近NS和NE向逆断层与NW向走滑-掀斜断层组合是最重要的控矿构造。其中,近NE向逆断层与不整合面是成矿流体运聚的主要通道,而近于平行的NW向走滑-掀斜断层上盘的T_(3)s高孔渗性角砾状灰岩、含灰岩角砾砂岩及裂隙带因为富含H_(2)S等还原性流体而成为与Mio-j富含金属氧化性盆地卤水混合和金属沉淀就位的最有利空间。由此,逆断层和走滑-掀斜断层组合、特定地层岩性与不整合面联合控制了流体汇聚与混合成矿作用,断层沟通了同位叠加的上三叠统油气藏储层和渐新统-中新统盆地卤水(带),这是铅锌成矿的关键。该成矿模型在金顶矿田及邻区与类似地区均具有普遍指导意义。最后,本文预测沿跑马坪矿区深部及其南北侧延伸区域还存在多条NE向隐伏控矿断层,其成矿潜力大,是下一步找矿勘查的有利靶区。     

地面气象观测站自动检测系统研究

为了解决目前的计量检定标准设备和方法不适于地面气象观测站仪器,检测的自动化水平及工作效率低等矛盾,研究设计了地面气象观测站自动检测系统,特点是将地面气象观测站的温度、湿度、大气压力、风速风向和降水等传感器和地面气象观测站的数据采集器分开进行性能的自动检测.传感器自动检测系统采用多通道设计,可同时进行多个传感器的自动检测并自动输出检测结果.数据采集器自动检测系统可以对气象台站使用的各种不同的地面气象观测站数据采集器系统进行性能测试.文章所设计的地面气象观测站自动检测系统提高了地面自动观测仪器的检测效率,确保了各台站的地面气象自动观测仪器观测数据的准确可靠.     

雷电临近预警系统的运行试验

介绍了中国气象科学研究院研发的雷电临近预警系统(CAMSLNWS)在北京地区开展的业务运行试验.通过运行测试以及预警结果与闪电监测结果的对比评估,表明:CAMS.LNWS能够稳定运行,定时读取多种探测资料、自动生成并循环显示雷电发生概率、雷电活动区域移动趋势和重点区域雷电危险度等级三种雷电临近预警产品;CAMS.LNWS的雷电发生概率预警产品具有较高的命中率,能够较好地对0～30min内可能发生闪电的区域进行有效预警;随着预警时间的延长,CAMS.LNWS的预警效果会有所降低.     

基于局部阈值插值的地基云自动检测方法

地基云自动化观测是当前气象业务发展的迫切需求.目前的地基云检测算法仍主要是以阈值为基础,针对固定阈值和全局阈值算法在云检测精度方面存在的不足,利用晴朗天空下天空呈蓝色、云呈白色的属件,提出了一种基于局部阈值插值的地基云自动检测方法.该方法在对云图进行重采样后,对云图蓝、红波段进行归一化差值处理,再将处理后的结果图像按空间像素位置自动分成互不重叠、大小相等的均匀子块,对每一子区域采用一定的规则并结合改进的最大类间方差自适应阈值算法计算局部阈值,然后对每一子区域形成的阈值矩阵采用双线性插值算法进行插值处理,形成与原始云图大小相等的阈值曲面,利用此阈值曲面与云图蓝、红波段归一化差值处理结果进行比较,即可完成地基云的自动检测.与固定阈值和全局阈值算法相比,局部阈值插值算法对一些细碎的云和与背景反差不大的云获得了更好的检测效果.定量的评估结果表明,固定阈值方法在正确率和精确度上都要远远低于全局阈值和局部阈值方法,而文中提出的局部阈值算法在正确率和精确度上相比全局阈值算法又有较大提高.     

Urban and rural observations of carboxylic acids in rainwater in Southwest of China: the impact of urbanization

Seven carboxylic acids in rainwater were simultaneously determined using ion chromatography for 13 months in two different sites, Guiyang and Shangzhong, southwest of China. Results showed formic, acetic and oxalic acids were the three predominant carboxylic acids. Their volume-weighted average concentrations were 14.24, 9.35, 2.79 μmol/L in Guiyang and 4.95, 1.35, 2.31 μmol/L in Shangzhong, respectively. A distinctive diurnal pattern in carboxylic acid concentrations (daytime>nighttime, t test, p < 0.05) was observed during the growing season in Guiyang. Shangzhong witnessed higher concentration of these acids during the growing season than that during the non-growing season. Direct emissions from growing vegetation or soils probably account for the main provenance of the acids in the rural area. However, the opposite trend were found in Guiyang and the anthropogenic sources during the non-growing season were the main reason. By comparison of our result with the previous data about 20 years ago, we calculated that at least 42% of acetic acids and 69% of formic acid originated from the anthropogenic sources in Guiyang. Furthermore, the ratio of formate/acetate in gas phase larger than 1 suggest the oxidation of unsaturated hydrocarbons from the human activity and/or natural sources were the main origin of carboxylic acids in Guiyang. While The F/A ratio in gas phase was less than 1 in Shangzhong which indicate the direct emissions from biogenic sources. Oxalic acid was in similar amounts in both sites, indicating the common source of the acid.     

震后基于无人机快速三维定位被困人员模型研究

针对震后被倒塌建筑物或滑坡埋压的被困人员进行快速定位问题，在阅读大量相关文献的基础上，以无人机遥感、地理信息空间和三维质心定位技术为基础，采用无线信号RSSI测距模型，配合影像范围内基准影像数据辅助定位，构建震后基于无人机快速三维定位被困人员模型。以红河县城区作为研究区，对城区内特定人员进行三维定位，结果表明该模型定位精度高，对震后废墟被困人员营救具有重要意义。