Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

气溶胶光学厚度的时空变化

在大气中气溶胶微粒是一种重要的大气微量成分。气溶胶光学厚度也是大气校正所需的重要大气参数，同时也是海洋水色卫星主要的数据产品。由于气溶胶光学厚度的时空变化较大，所以如何准确获取大气校正和卫星数据产品真实性检验所需的气溶胶光学厚度则是至关重要的。在简述气溶胶光学性质的基础上，并结合2002年6月HY—1南海实验数据来阐述现场气溶胶光学厚度的准确获取。     

Reconstruction of sea surface dimethylsulfide in the North Pacific during 1970s to 2000s

We proposed an empirical equation of sea surface dimethylsulfide (DMS, nM) using sea surface temperature (SST, K), sea surface nitrate (SSN, μM) and latitude (L, °N) to reconstruct the sea surface flux of DMS over the North Pacific between 25°N and 55°N: ln DMS = 0.06346 · SST − 0.1210 · SSN − 14.11 · cos(L) − 6.278 (R² = 0.63, p < 0.0001). Applying our algorithm to climatological hydrographic data in the North Pacific, we reconstructed the climatological distributions of DMS and its flux between 25 °N and 55 °N. DMS generally increased eastward and northward, and DMS in the northeastern region became to 2–5 times as large as that in the southwestern region. DMS in the later half of the year was 2–4 times as large as that in the first half of the year. Moreover, applying our algorithm to hydrographic time series datasets in the western North Pacific from 1971 to 2000, we found that DMS in the last three decades has shown linear increasing trends of 0.03 ± 0.01 nM year^− 1 in the subpolar region, and 0.01 ± 0.001 nM year^− 1 in the subtropical region, indicating that the annual flux of DMS from sea to air has increased by 1.9–4.8 μmol m^− 2 year^− 1. The linear increase was consistent with the annual rate of increase of 1% of the climatological averaged flux in the western North Pacific in the last three decades.     

改进的自适应遗传算法在遥感图像分割中的应用

为了自动确定遥感图像分割的最佳阈值,本文提出了一种改进的自适应遗传算法,并利用该算法对二维Otsu图像阈值分割函数进行了全局优化,提高了分割闻值的求解速度。该算法能够根据个体适应度大小和群体的分散程度自动调整遗传控制参数,从而能够在保持群体多样性的同时加快收敛速度,克服基本遗传算法的收敛性差、易早熟问题。实验结果表明,该算法具有良好的收敛速度和稳定性,达到较好的图像分割效果,大大缩短了计算时间。     

基于退火BP神经网络的GPS高程转换

阐述模拟退火算法的基本思想和原理,提出并介绍模拟退火算法优化的BP神经网络模型在GPS高程转换中的具体应用,同时编写相应的MATLAB处理程序,结合大量数据进行仿真实验,结果表明文中提出的退火BP神经网络模型具有收敛速度快、精度高、避免陷入局部最小的优良特性。     

Learning to trade ethically: Knowledgeable capitalism, retailers and contested commodity chains

This paper explores what happens when corporations engage explicitly in practices of organisational learning not only to become better capitalists by generating ever more innovative ways of maintaining profitability, improving competitiveness and maximising shareholder value, but also to become more responsible corporate citizens in their business practices. In particular, I evaluate the ways in which UK food and clothing retailers are learning to develop their ethical trading programmes in response to political calls for more responsible trading. Thrift’s [Thrift, N., 2005. Knowing Capitalism. Sage, London] notion of ‘knowledgeable, or soft, capitalism’ is adopted to understand the creative and experimental ways in which retailers and their mentors (ethical consultancies, social auditors and multi-stakeholder organisations) are learning to trade ethically. Two specific examples of formal learning spaces experienced by UK food and clothing retailers are examined: (i) training courses on social auditing and (ii) corporate awareness-raising courses on ethical trade. These courses are shown to encompass various participative and affective practices of learning. And while particular limits to the success of these courses are argued to exist, ethical learning practices discussed in this paper are nonetheless suggested to play a role in the making of new, albeit moderate, forms of responsible capitalism.     

Towards models of strategic spatial choice behaviour: theory and application issues

Models of spatial choice behaviour have been around in geography urban planning for decades to assess the feasibility of planning actions or to predict external (competition) effects on existing destinations. Although these models differ in terms of complexity and key concepts, they all have in common that spatial choice behaviour is predicted as a function of the attributes of the choice alternatives and distance or travel time separation only. None of these models do take into account that the attributes of choice alternatives and travel time may be highly non-stationary and that often the utility that people derive from visiting a particular location also depends on the choice behaviour of other individuals. Under these circumstances, individuals may exhibit strategic choice behaviour. That is, they will choose particular choice options taking into account their expected behaviour of others such as to maximize their own utility. The purpose of the proposed paper is to discuss possible models of strategic choice behaviour for these urban planning problems. Theory will be outlined and some critical issues in the application of such models to problems of spatial choice will be discussed.     

基于GIS的商业网点选址研究与实现

利用平面／网络优化模型，综合权衡市区选址的基本费用及商业网点日常经营的成本，引入交通便利因子作为限制条件，并运用直接搜索的Dixon方法，加强了不确定性选址问题的约束条件，降低不确定性问题计算的复杂度，减少在选址问题实现中主观因素对选址结果的影响。最后以某区新建商业网点选址为例，详细分析了直接搜索算法应用的具体过程。     

基于正交投影和广义投影(POCS)算法的研究进展

目的 在于提请有关读者关注近年来关于图像重建的凸集投影算法的进展，这一重要的方法及应用。方法 主要讨论了基于正交投影和广义投影的算法。对基于正交投影的算法，并讨论了一般形式的加权松驰格式，这包含了分块格式和同时格式。并以三个定理报道有关的算法收敛性结果。结果 分别包含了相容和不相容条件和弱强收敛下的结果。对基于广义投影的算法，有关的基本概念和例子，基本算法的收敛性结果。结论 报道最近关于引入松弛系数的工作和在CT图像重建中的应用。     

a′Trous小波变换与PCA变换相结合的遥感影像融合分析

随着高分辨率遥感卫星的产生,传统的融合技术难以达到较好的融合效果,如主成分分析(PrincipalComponents Analysis)变换融合受到融合区域的限制,而传统的小波融合(Wavelet Transformation)算法由于高频直接替换,导致了一定程度的光谱失真,由此本文在分析主成分分析变换和a′Trous小波变换(WT)的基础上,以QuickBird全色和多光谱数据为实验数据,提出了一种将两者相结合的遥感影像融合方法,通过与其他融合方法的定量和视觉比较,结果表明该方法能得到更好的融合效果。