Governance fit for climate change in a Caribbean coastal-marine context

Coastal-marine systems in small island developing states of the Caribbean are highly vulnerable to both current and future climate change. Societies navigate these changes in part through processes of governance and the institutions through which governance takes place. The concept of institutional adaptive capacity is used to explore how governance processes and institutional arrangements can be adapted to match the scale and extent of climate change in a case study of the Soufriere Marine Management Area, St. Lucia. Institutional adaptive capacity is analyzed based on the following factors: institutional variety, analytical deliberation and nesting and networks. The analysis is based on 36 semi-structured interviews conducted with key informants from NGOs, cooperatives, management authorities and government agencies. The findings suggest that governance to address climate change in the case study is contingent upon developing holistic, integrated management systems, improving flexibility in existing collaborative decision making processes, augmenting the capacity of local management authorities with support from higher-level government, exploring opportunities for private–social partnerships, and developing adequate social–environmental monitoring programs. These findings have potential implications and lessons for similar settings throughout the Caribbean.     

一种自适应的坡度阈值地面点云分割方法

针对城市道路斜坡地形场景中地面欠分割或过分割的问题,提出了一种自适应的激光雷达地面分割算法。首先将激光点云按照水平角度分辨率进行有序组织,然后求取同一水平角度下前后扫描圈间激光点云的距离和局部坡度,最后采用自适应水平距离、局部高度和全局高度阈值区分地面点和非地面点。结合40线激光雷达进行多场景实例分析,结果表明本文算法分割的准确率更高,处理每帧数据均用时约1ms,满足无人驾驶汽车的实时性需求。提出了一种自适应的激光雷达地面分割算法,实现了对激光雷达地面点云的准确分割。     

European Solar Telescope: Progress status

In this paper, the present status of the development of the design of the European Solar Telescope is described. The telescope is devised to have the best possible angular resolution and polarimetric performance, maximizing the throughput of the whole system. To that aim, adaptive optics and multi‐conjugate adaptive optics are integrated in the optical path. The system will have the possibility to correct for the diurnal variation of the distance to the turbulence layers, by using several deformable mirrors, conjugated at different heights. The present optical design of the telescope distributes the optical elements along the optical path in such a way that the instrumental polarization induced by the telescope is minimized and independent of the solar elevation and azimuth. This property represents a large advantage for polarimetric measurements. The ensemble of instruments that are planned is also presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

EST Adaptive optics performance estimations

We give a short overview of the Adaptive Optics (AO) and Multi‐conjugate Adaptive Optics (MCAO) system of the planned 4 m European Solar Telescope (EST). The optimization process of the AO / MCAO parameters is shown, including the parameters and layout of the Shack‐Hartmann wavefront sensor setup and the DMs. We show the expected performance of the AO and MCAO system (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Fully coupled time-domain simulation of dynamic positioning semi-submersible platform using dynamic surface control

A fully coupled 6-degree-of-freedom nonlinear dynamic model is presented to analyze the dynamic response of a semi-submersible platform which is equipped with the dynamic positioning （DP） system. In the control force design, a dynamic model of reference linear drift frequency in the horizontal plane is introduced. The dynamic surface control （DSC） is used to design a control strategy for the DP. Compared with the traditional back-stepping methods, the dynamic surface control combined with radial basis function （RBF） neural networks （NNs） can avoid differentiating intermediate variables repeatedly in every design step due to the introduction of a first order filter. Low frequency motions obtained from total motions by a low pass filter are chosen to be the inputs for the RBF NNs which are used to approximate the low frequency wave force. Considering the propellers’ wear and tear, the effect of filtering frequencies for the control force is discussed. Based on power consumptions and positioning requirements, the NN cen-ters are determined. Moreover, the RBF NNs used to approximate the total wave force are built to monitor the disturbances. With the DP assistance, the results of fully coupled dynamic response simulations are given to illustrate the effectiveness of the proposed con-trol strategy.     

组合导航中一种新息自适应卡尔曼滤波算法

全球定位系统/航位推算组合导航定位中,由于目标运动的不确定性,GPS接收机与DR器件接收的数据存在噪声,使预置目标运动模型通常很难得到较高跟踪精度,针对应用常规卡尔曼滤波进行组合导航解算由于噪声统计特性未知而引起滤波不稳定的问题,本文提出了一种基于新息序列的量测计算进行自适应估计的卡尔曼滤波算法。该算法通过对新息方差强度进行极大似然估计,将新息计算引入卡尔曼滤波器的增益计算,达到控制发散的目的。最后对改进的算法与一般卡尔曼滤波算法做了对比仿真试验分析,结果表明了改进算法的有效性。     

Model of optical turbulence profile at Cerro Pachón

New measurements of optical turbulence profile at the Cerro Pachón observatory in Chile are analysed jointly with previously published data to model the variations of the intensity and thickness of the ground layer and free atmosphere under a variety of observing conditions. This work is motivated by the need to predict statistically the performance of ground-layer adaptice optics. We find that the ground-layer profile can be represented by a decaying exponent with a scale height of 20–40 m, increasing to 100 m under bad conditions. The zone from 6 to 500 m contributes typically about 61 per cent to the total integral, the latter causing a median seeing of 0.77 arcsec. Turbulence integrals in the ground layer and in free atmosphere vary independently of each other, in 50 per cent of cases they deviate by less than 1.8 times from their respective median values. The existence of periods with low turbulence in the free atmosphere and their importance for adaptive optics is stressed.     

Phasing segmented mirrors using defocused images at visible wavelengths

Plans for future optical telescopes of diameter more than 10 m are based on segmented mirrors, made up of hundreds or even thousands of segments. A challenge for these telescopes is the alignment in piston (cophasing) where phase differences between individual segments have to be reduced to a small fraction of the observing wavelength in order to avoid degradation of image quality.
Based on the phase discontinuity sensing method used at the Keck telescopes to measure small piston errors using infrared wavelengths, we develop a new method that allows fast high-precision measurements of large piston errors even at visible wavelengths.     

复杂背景下的仿蝇视觉遥感异常检测

本文针对遥感影像复杂背景下,背景地物光谱特征与目标光谱特征之间存在较强相关性的问题,提出一种基于仿蝇视觉的复杂背景下遥感异常检测算法。首先构建并行多孔径背景模型,实现对复杂背景特征的自适应描述;然后基于异常目标的光谱特征相对异常性,采用相对马氏距离区分异常区域、不确定区域与无目标区域,消除背景与目标光谱相关性对检测结果干扰的同时,弥补了传统假设检验无法区分无目标和不确定问题的不足;最后融合多个背景模型的检测结果,实现异常目标检测。仿真实验将围绕多种背景地物并存复杂区域的异常检测验证本文算法的有效性。     

一种结合四元数与直方图的多光谱图像自适应边缘检测方法

针对图像自适应边缘检测的难点和传统多光谱遥感图像边缘检测方法的局限性,提出了一种结合四元数与直方图的自适应边缘检测方法。该方法在四元数空间,利用矢量旋转完成了多光谱图像的边缘检测,并通过直方图统计的方法获取自适应阈值,实现了边缘图像的检测。利用陆地多光谱遥感图像和水域多光谱遥感图像分别进行实验,验证了方法的有效性。