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391.
This paper examines the development and effects of a rapid livelihood transition on households, and reflects on how it fits within historic trends of livelihood change for people living in highly variable and vulnerable environments. It also discusses the implications of livelihood dynamism for local governance of natural resources. In recent decades, seaweed cultivation has expanded exponentially in coastal communities across the Asia-Pacific. A case study is presented of a remote small-island community in eastern Indonesia where over the last ten years a dramatic shift in livelihood focus has occurred. Previous dependence on diverse low-productivity livelihood activities transitioned to a predominant focus on seaweed farming. The case shows how social, economic and cultural environments co-develop as people move out of conditions of collective poverty and into more nuclear household-oriented livelihood activities. Specific attention is given to the influence on a marine resource co-management program operating on the island to illustrate how local livelihood dynamics relate to broader paradigm-driven conservation and rural development initiatives. While alternative livelihood programs seek to relieve pressure on resource stocks and provide opportunities for coastal people, this case study provides timely insights into the kinds of unintended effects, trends and impacts that are associated with rapid change in the way people make a living. This study argues that, in addition to achieving higher standards of income and well-being, livelihood improvement interventions need to adequately ensure that conditions under which new livelihood arrangements come to function can be maintained locally.  相似文献   
392.
从专家目视判别晴空地表与云雾的原理出发,针对不同时区晴空地表与云雾分离检测算法的难点进行了研究,提出一种适应于不同时区的白天晴空地表与云雾分离的遥感检测算法。应用10幅不同时区MODIS图像对算法的可行性、稳定性及精度进行评定的结果表明,该算法可行性较强,稳定性较高,且不需人工干预。  相似文献   
393.
The temperature induced structural evolution and thermoelastic behaviour of a natural (Pbca) orthopyroxene (Opx), with chemical formula M2(Mg0.856Ca0.025Fe2+ 0.119) M1(Mg0.957Fe2+ 0.011Fe3+ 0.016Cr0.011Al0.005)Al0.032Si1.968O6, from a suite of high pressure ultramafic nodules of mantle origin, have been investigated by in-situ neutron powder diffraction at several temperatures starting from 1,200°C down to 150°C. Unit-cell parameter variations as a function of T show no phase transition within this temperature range. The volume thermal expansion coefficient, α = V −1(∂V/∂T) P0, varies linearly with T. The axial thermal expansion coefficients, αj = l j−1(∂l j/∂T)P0, increase non-linearly with T. The principal Lagrangian unit-strain coefficients (ɛ//a, ɛ//b, ɛ//c), increase continuously with T. However, the orientation of the unit-strain ellipsoid appears to change with T. With decreasing T, the values of the unit-strain coefficients along the b and c axes tend to converge. The orientation at ΔT = 1,080°C is maintained down to the lowest temperature (150°C). The two non-equivalent tetrahedral chains, TA n OA3n and TB n OB3n , are kinked differently. At room-T, the TB n OB3n chain is more strongly kinked by about 23° than the TA n OA3n chain. With increasing T, the difference decreases by 3° for the TB n OB3n chain. The intersite cation exchange reaction between M1 and M2 (Mg2+ and Fe2+) shows a slight residual order at 1,200°C followed by reordering with decreasing temperature although seemingly not with a definite progressive trend. At the lowest temperature reached (150°C), reordering has occurred with the same value of partitioning coefficient K D as that before heating. The absence of the expected phase transition is most likely due to the presence of minor amounts of Fe3+, Al, Ca and Cr which must play a crucial role on the thermoelastic behaviour and phase stability fields in natural Opx, with consequent important petrologic and geological implications.  相似文献   
394.
随着城市的扩大,泉州市在完成新一轮精度较好的GPS/水准网布测与数据处理的基础上,通过收集、整理泉州市及周边地区陆地重力测量资料、国内外先进的地球重力场模型,采用先进的(似)大地水准面确定理论与方法,完成了泉州市规划区精度优于3 cm的似大地水准面的确定工作.  相似文献   
395.
Understanding the linkages between social and ecological systems is key to developing sustainable natural resource management (NRM) institutions. Frequently, however, insufficient attention is paid to the historical development of NRM institutions. Instead, discussion largely focuses on models of economic efficiency at the expense of the cultural, historical, and ecological contexts within which institutions develop. Here we use the research program of historical ecology to explore the development, maintenance, and change of two contemporary fire management institutions in northern Australia and Colorado, USA, to demonstrate how social institutions and ecological systems change and resist change over time and how institutions interact across scales to negotiate contrasting goals and motivations. We argue that these NRM institutions are not strictly speaking evolutionary or adaptive, and that historical context is critical when evaluating how and why particular institutions and institutional relationships develop. As with ecosystems, the present characteristics of the NRM institutions are dependent on what has happened before and their efficacy can only be evaluated retrospectively. Therefore, an understanding of history is essential to questions of the desirability and feasibility of institutional change where such shifts are required from an ecological, social, or economic perspective. We further propose that institutional conflict arises from the differing goals and motives of resource management institutions at different scales. Our cases reveal that larger-scale institutions can be successful at achieving narrowly defined goals but often fall short of achieving socially desirable sustainable outcomes. Our findings support the use of narratives of community history, place, and being in considering the resilience and sustainability of social-ecological systems. We offer that historical ecology is complementary with institutional and economic approaches to the analysis of NRM institutions, and possesses a particular strength in linking ecology to the values and norms of small social groups.  相似文献   
396.
自适应Kalman滤波反褶积的快速实现方法   总被引:6,自引:2,他引:6       下载免费PDF全文
提出了以二进小波变换为基础的自适应Kalman滤波反褶积(AKFD)新方法,针对该方法的计算复杂程度,提出了一种快速实现方法.二进小波变换的AKFD抛弃了传统预测反褶积对信号平稳性的假设,克服了提高分辨率而信噪比明显降低的问题,具有很好的抗噪性能.在小波域进行的AKFD在压制假反射以及提高分辨率方面比时间域的AKFD好,克服了在时域内进行AKFD抬升低频成分的缺陷.利用二维地震数据的局部平稳性的假设提出了快速实现方法,通过分段求取自适应预测算子,分别于横向及纵向采用样条插值的方法进行插值,来减少求取自适应预测算子的计算量,达到快速实现的目的.经过大量实验表明计算速度提高数百倍,仍能保持原来的计算效果.  相似文献   
397.
The aftermath of Hurricane Sandy brings to light the tenuous U.S. model of natural disaster management. Climatic extremes, like Sandy, are projected to increase in magnitude and frequency, calling upon societies to adapt appropriately to imminent threats. In this paper, we describe the knowledge and policy disconnect exposed by Sandy between what we submit are four key elements of adaptive capacity: resources, institutions, knowledge and innovation of technology. Our synthesis of multi-disciplinary expert knowledge and admonition from civil engineers, climatologists, and urban planners demonstrates the significance of mobilizing knowledge to design robust socio-ecological systems. We contrast the U.S. model to the Dutch system of climate adaptation to emphasize the feasibility, value, and effectiveness of adopting robust adaptive capacities, rather than policies steeped in reactionary responses. Such strategies that integrate coordination and imagination from members across society are imperative in translating scientific foresight into institutional action. The solution we offer is not only material for a more action-based discussion, but also provides an illustration of crafting policy that enhances adaptive capacities of socio-ecological systems.  相似文献   
398.
数值模式已经成为天气预报业务发展的主要方向,数值模式计算产生各种气象网格产品。气象网格产品具有数据量大、更新频次快、专业性强等特点,需要借助专业工具软件进行处理,不能很好满足企业和社会用户使用的需求,应用范围受到极大的限制。面对气象网格产品专业化与气象数据应用需求简单化之间的矛盾,文章提出针对气象网格产品,尤其是实况网格产品和预报网格产品,采用互联网服务手段,通过对网格数据离散化处理的方法,空间化管理的方式,将WebGIS技术应用到气象网格产品服务中。用户在客户端只需要进行简单文字检索或者GIS图形检索,系统便可以实现对气象网格产品中的有效数据进行精细化抽取,最终实现服务精细。文中提出的数据处理方法,对不同行业间气象网格产品的应用起到指导作用。  相似文献   
399.

地震数据采集过程中, 由于采集成本的制约, 炮点间距相对检波点间距大, 导致地震数据一致性弱, 影响自由表面多次波衰减与偏移成像的精度.较大的炮点间距使得共检波点道集在傅里叶变换域出现严重的空间假频, 给压缩感知插值重建方法带来巨大挑战, 需研究抗假频机制.本文利用深度学习强大的非线性表征能力, 设计结合ResNet和U-net优势的Res-U-net网络; 运用格林函数空间互易性, 自适应构建训练集, 利用共炮点道集对设计的网络进行训练和验证, 应用于共检波点道集, 实现缺失炮的智能重建.为了进一步提高缺失炮重建精度, 基于地震数据的周期和波长属性, 设计合理的卷积核大小, 并考虑地下速度变化情况, 利用扩张卷积组合实现高效高精度地震数据表征, 达到缺失炮插值重建的目的.模拟数据分析和实际资料处理验证了基于周期和波长的卷积核设计的合理性以及扩张卷积的有效性, 为后续偏移成像提供横向连续性较好的地震数据.

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400.

海洋可控源电磁法(MCSEM, Marine Controlled-Source Electromagnetic Method)是一种工业化的主动源海洋电磁勘探方法, 近年来在海底油气资源探测中收效显著, 通过测量海底地下介质的电阻率变化, 能够有效降低地震勘探方法的多解性.MCSEM的工作方式主要有单船拖曳与双船拖曳两类.单船拖曳信号具有强时变特征, 近、中、远收发距信号强度变化极大.由于海水环境较为复杂, 数据受到洋流、背景场、仪器等多种因素干扰, 使得小收发距数据信噪比较高, 中、远收发距数据信噪比较低, 因此MCSEM数据随机干扰压制方法的研究难点在于适应数据的强时变特征.本文利用发射机数据与接收机数据的时间(空间)和频率对应关系, 提出基于正则化条件和衰减函数约束的自适应分频匹配滤波方法.该方法首先通过计算原始接收机数据基频的振幅随偏移距变化(MVO, Magnitude Versus Offset)曲线获取衰减函数, 然后利用该衰减函数将发射机所有频点数据进行振幅衰减, 减低MCSEM发射机与接收机数据对应振幅的强时变差异, 最后利用基于整形正则化条件的自适应匹配滤波方法压制接收机数据中的强振幅随机噪声.模型数据与实际数据的处理结果表明, 本文提出的方法能够有效压制MCSEM数据中不同收发距的随机噪声干扰, 保护具有强时变特征的接收机数据, 提升整体数据质量.

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