Integrating remote sensing in fisheries control

Abstract  To complement existing fishery control measures, in particular the Vessel Monitoring System (VMS), a pilot operational system to find fishing vessels in satellite images was set up. Radar is the mainstay of the system, which furthermore includes fully automated image processing and communication protocols with the authorities. Different image types are used to match different fisheries – oceanic, shelf and coastal. Vessel detection rates were 75–100% depending on image type and vessel size. Output of the system, in the form of an overview of vessel positions in the area highlighting any discrepancies with otherwise reported positions, can be at the authorities within 30 min of the satellite image being taken – fast enough to task airborne inspection for follow up.     

Estimating aboveground biomass in forest and oil palm plantation in Sabah, Malaysian Borneo using ALOS PALSAR data

Conversion of tropical forests to oil palm plantations in Malaysia and Indonesia has resulted in large-scale environmental degradation, loss of biodiversity and significant carbon emissions. For both countries to participate in the United Nation’s REDD (Reduced Emission from Deforestation and Degradation) mechanism, assessment of forest carbon stocks, including the estimated loss in carbon from conversion to plantation, is needed. In this study, we use a combination of field and remote sensing data to quantify both the magnitude and the geographical distribution of carbon stock in forests and timber plantations, in Sabah, Malaysia, which has been the site of significant expansion of oil palm cultivation over the last two decades. Forest structure data from 129 ha of research and inventory plots were used at different spatial scales to discriminate forest biomass across degradation levels. Field data was integrated with ALOS PALSAR (Advanced Land-Observing Satellite Phased Array L-band Synthetic Aperture Radar) imagery to both discriminate oil palm plantation from forest stands, with an accuracy of 97.0% (κ = 0.64) and predict AGB using regression analysis of HV-polarized PALSAR data (R² = 0.63, p < .001). Direct estimation of AGB from simple regression models was sensitive to both environmental conditions and forest structure. Precipitation effect on the backscatter data changed the HV prediction of AGB significantly (R² = 0.21, p < .001), and scattering from large leaves of mature palm trees significantly impeded the use of a single HV-based model for predicting AGB in palm oil plantations. Multi-temporal SAR data and algorithms based on forest types are suggested to improve the ability of a sensor similar to ALOS PALSAR for accurately mapping and monitoring forest biomass, now that the ALOS PALSAR sensor is no longer operational.     

Free vibration characteristic analysis of the elastic liquid-storage tanks based on the bending shearing model

Liquid-storage tanks, mostly used to reserve rinsing, sewerage, petroleum and chemistry liquid, are broadly applied in such industry corporations as water-supply and drainage industry, sewerage-disposal industry, petroleum industry, chemistry industry and so on. For the sake of computing preferably earthquake responding of these structures, the characteristics of their free vibration, like frequency of free vibration and corresponding oscillation-mode, have to be known beforehand. Therefore, for the liquid-storage tanks without liquid, the equations about oscillation-mode and frequency based on bending-shearing model are deduced, and at the same time, the calculation tables and chart of former three oscillation-modes are presented by using MATLAB program, and free vibration characteristics using different deformation theory in different heights are analyzed. The correctness of the result is proved by calculation example, and a theory base is provided for analyzing subsequent free vibration and earthquake responding of this type of structure.     

高把油锯振动特性的研究

只有搞清油锯的振动特性,找出油锯振动的根源并掌握其振动规律,才能有的放矢地制订出减振方案并为新型低振动油锯的研制打下良好的理论基础。一、研究对象和测试仪器研究对象和测试样机,选取西北林机厂生产的GJ-85型油锯,柳州机械厂的051型油锯和苏联的урал-2型油锯。样机皆经磨合和试运转。测试仪器选用YD-8型和YD-1型压电式加速度传感器。前者频率范围2-18KHZ,     

论信息时代电大图书馆发展问题

二十一世纪给电大图书馆带来了机遇和挑战，本文论述了电大图书馆发展应重视的几点问题：①立足实际，制定好自身规划；②正确对待印刷型文献；③强化馆员的继续教育。     

传感器输出特性的线性处理

介绍了传感器电源和放大电路在系统中的重要性，提出了通过合理设计传感器电源、信号放大电路以及用面向对象程序设计方法编制的线性回归数据处理程序达到提高系统精度和可靠性的方法。     

地质雷达技术及其在侵蚀产沙中的应用初探

侵蚀泥沙资料对于研究土壤侵蚀规律具有重要的意义。地质雷达（GPR）为侵蚀产沙的研究提供了一种快速、和高精度经济的地球物理方法；地质雷达利用高频电磁波在介电特性不均匀的介质中产生反射获得剖面图像，通过解译可确定地下沉积物的性质和结构。在简要阐述地质雷达技术的基本工作原理的基础上，介绍了地质雷达技术在成都市百工堰水库进行塘库沉积物调查的具体应用。研究结果表明，地质雷达具有较强的勘察能力，水体与沉积物及基岩间的界面在雷达图像中清晰可见，通过雷达剖面可清楚地观察到水底的起伏情况与沉积物的分布情况。     

吉林省盛夏最强的一次雷暴大风天气分析

利用高（低）空观测数据、多普勒雷达等相关资料,从天气背景、热力条件、水汽分布、能量场分布特征、不稳定度参数特征等方面,分析了2006年7月13日吉林省盛夏最强的一次雷暴大风天气过程的形成机制.结果表明,这次雷暴大风天气是由飑线造成的,低空增温、增湿与对流层中层干侵入的相互作用下使得对流风暴发展旺盛,下沉气流外流,导致地面出现强风;多普勒雷达提供的反射率因子及径向速度图能有效监测雷暴大风,反射率因子回波为带状或线状,在径向速度图上有大风区和中层径向速度辐合,风场上有明显的垂直切变,这些指标对大风预报有较好的指示意义.     

一次冷涡降雹的雷达回波特征分析

利用烟台多普勒天气雷达资料,重点从雷达反射率因子形态演变、径向速度场结构特征、VWP风廓线和风暴追踪信息等方面入手,对2010年5月30日早晨发生在烟台地区的冰雹天气进行分析,综合分析此次冷涡降雹的中尺度特征。结果表明,造成此次冷涡降雹的系统具有明显的超级单体风暴特征,其初始回波高度在6 km左右,向上和向下发展迅速,垂直累积液态水含量(VIL)值在降雹前有明显的变化,VWP风廓线产品上降雹前在低层有冷层的存在,对冰雹的产生有一定的指示意义。     

秦岭北麓一次暴雨天气在风廓线雷达资料中的分析

[目的]分析2011年8月15日西安市长安区一次暴雨天气中风廓线雷达资料的变化特征。[方法]利用固定式边界层风廓线雷达资料,根据当地的地理环境,着重分析2011年8月15日西安市长安区一次暴雨天气的降水前和降水期间的风廓线资料,研究降水前和降水期间多普勒雷达图、风廓线资料的变化特征。[结果]对流天气来临前,风的脉动变化较大,水平风在垂直方向上2 000 m左右高度出现正的垂直风速切变,降水前最大探测高度明显升高;长安边界层风廓线雷达可获得时间和空间分辨率较高的风廓线资料,其探测到的水平风场资料可清晰地监测大风天气的发生和变化过程。长安区地处秦岭北麓,地形因素是一个很重要的需要考虑的条件,雷暴大风分布与阶梯地形相一致。[结论]该研究为长安的强对流天气分析提供科学依据。