湖北省降水量的周期分析   总被引：8，自引：0，他引：8  

吴宜进  邓先瑞 《热带地理》1998,18(3):201-204,215

结合降水量对农业生产的影响特点将全年降水量分成５个阶段,根据聚类分析的结果将不同的时段的降水量进行分区,由此对全省的降水量做自相关分析和功率谱分析,从而发现了降水量的变化周期。  相似文献   

地脉动及特殊波形的频谱特性在地震预报中的应用   总被引：3，自引：0，他引：3  

陈化然  郭瑞芝 《地震》1998,18(1):75-82

利用功率谱和Ｓｏｍｐｉ谱分析方法,对大震前地脉动及震前特殊波形等记录进行了比较深入的研究,结果表明：（１）较大地震前短周期地脉动及震前特殊波形频谱的峰值频率ｆｍ,拐角频率ｆｃ相对频带宽度△ｆ相对峰值Ｓｍ／Ｓ０,高频段的斜率绝对值│ｂ│及Ｓｏｍｐｉ谱的卓越频率ｆｄ等特征量均可能出呈现出较明显的下降（少数为上升）异常变化。（２）各频谱特征量呈现异常的时间基本上同步,并与波速异常发展趋势基本相符,（３）  相似文献   

关于我国电力建设问题     

陆大道 《云南地理环境研究》1990,2(1):10-13

本文在分析我国能源资源分布特点,总结过去电力建设经验的基础上,通过水、火电全面经济效益比较,认为,在我国具体的国情和国力条件下,今后必须贯彻优先开发水能的方针,并提出了因地制宜发展水电建设应注意做好的四项工作。  相似文献   

Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves     

《Applied Ocean Research》2015

Compared with solar and wind energy, wave energy is a kind of renewable resource which is enormous and still under development. In order to utilize the wave energy, various types of wave energy converters (WECs) have been proposed and studied. And oscillating-body WEC is widely used for offshore deployment. For this type of WEC, the oscillating motion of the floater is converted into electricity by the power take off (PTO) system, which is usually mathematically simplified as a linear spring and a damper. The linear PTO system is characteristic of frequency-dependent response and the energy absorption is less powerful for off resonance conditions. Thus a nonlinear snap through PTO system consisting of two symmetrically oblique springs and a linear damper is applied. A nonlinear parameter γ is defined as the ratio of half of the horizontal distance between the two oblique springs to the original length of both springs. JONSWAP spectrum is utilized to generate the time series of irregular waves. Time domain method is used to establish the motion equation of the oscillating-body WEC in irregular waves. And state space model is applied to replace the convolution term in the time domain motion equation. Based on the established motion equation, the motion response of both the linear and nonlinear WEC is numerically calculated using 4th Runge–Kutta method, after which the captured power can be obtained. Then the influences of wave parameters such as peak frequency, significant wave height, damping coefficient of the PTO system and the nonlinear parameter γ on the power capture performance of the nonlinear WEC is discussed in detail. Results show that compared with linear PTO system, the nonlinear snap through PTO system can increase the power captured by the oscillating body WEC in irregular waves.  相似文献   

The PISA grammar decodes diverse human–environment approaches     

《Global Environmental Change》2015

Human–environment interactions are studied by several groups of scholars who have elaborated different approaches to describe, analyze, and explain these interactions, and eventually propose paths for management. The SETER project (Socio-Ecological Theories and Empirical Research) analyzed and compared how “flag-holders” of distinct school of thought in human–environment scholarship approached a number of empirical problems of environmental management. This paper presents the findings from this experiment by concentrating on how representatives of four schools of thought approached one of these case studies: the plant health crisis in greenhouse tomato production in south of France. Our analysis suggests that these approaches share a common conceptual vocabulary composed of four explanatory elements of change (Power, Incentives, System and Adaptation-PISA). We argue that what distinguishes these schools from one another is the syntax—the “rules” by which researchers in each of the sub-disciplines tend to organize the components of this shared conceptual vocabulary. In other words, the schools under scrutiny are differentiated not so much by what they speak of, but rather in what order, or hierarchy, do they tend to rank the importance and/or the sequence of each of these concepts in human–environment explanations. The results of our experiment support the view that communication and cooperation across the diverse human–environment traditions is possible and productive. At the same time, however, we argue that it is the distinctiveness of the claims yielded by these different schools of thought that augment our collective understanding of complex socio-ecological problems. Attempts to integrate these perspectives in one unitary approach would undermine the intellectual wealth necessary to meet the challenges of the Anthropocene.  相似文献   

多相滤波器组谱分析方法的性能讨论与天文观测应用     

朱凯  甘恒谦  朱岩  金乘进 《天文研究与技术》2011,8(1)

多相滤波器组(PFB)是均匀数字滤波器组的一种高效实现结构,用于信号的均匀子带分解和抽取,对应用多相滤波器组作为功率谱估计器的统计性能与计算量进行分析,与相关图与周期图方法进行比较,并通过仿真及FAST密云模型21cm中性氢谱线观测检验其应用效果。  相似文献   

Making spaces: The ethnic Brao people and the international border between Laos and Cambodia     

Ian G. Baird 《Geoforum》2010,41(2):271-281

On December 6, 1904 the present international border between Laos and Cambodia was unilaterally established when the French colonial government extracted Stung Treng Province from Laos and transferred it to Cambodia. The ethnic Brao people living in the border region were not well known to the French, and in any case, their views were not deemed important. But since then the Brao have utilised this state administrative boundary in ways not intended by its designers, or governments since then, to give them more power to create new spaces. When conditions in Cambodia have been deemed unfavourable, the Brao have often crossed into Laos, and similarly, when circumstances have been less advantageous in Laos they have moved to Cambodia.This paper traces the history of the Brao as it specifically relates to the international border between Laos and Cambodia. While this administrative boundary was created to help national governments keep populations confined within nation-states, Brao human agency has sometimes confounded these efforts, through transforming its significance and role. The boundary has separated Brao populations in ways that are sometimes upsetting to them, but it has also allowed the Brao to position themselves at the margins of different nation-states, in spaces where they have been able to, at least temporarily, avoid or reduce state control over them. These are not non-state spaces; they are fundamentally constituted by a state-established boundary, even if the Brao have been able to mobilise this resource to empower themselves, and sometimes to resist the state itself.  相似文献   

“I’m an imaginary figure”: Unravelling the mobility and marginalisation of Scottish Gypsy Travellers     

Sergei Shubin  Kate Swanson 《Geoforum》2010,41(6):919-929

Gypsy Travellers have a long history of marginalisation in Scotland, but their mobility remains an issue of particular contention. Drawing upon a series of interviews with Gypsy Travellers in the North-East of Scotland, this paper uncovers how power and politics permeate discourses on movement to legitimise the spatial ordering of this traditionally nomadic group. The paper begins by exploring the more hidden and subtle aspects of mobility, such as the emotional and imaginative ties to travel. It then shifts to document how Gypsy Travellers’ geographies have been compromised by discriminatory policies and practices, which demonstrate a misunderstanding of the heterogeneity of their mobility. Consequently, increasingly punitive policies have pushed many Gypsy Travellers to abandon their travelling ways to move into “fixed” housing, while others have been forced into states of perpetual motion. The overall goal of the paper is to unravel the discursive constructions of movement in the context of institutionalised power and to document the spatial ordering of Gypsy Travellers’ lives, whose marginality has been legitimised by laws, ideologically sustained and reproduced in policy documents.  相似文献   

海洋教育：教育思想与实践的嬗变          下载免费PDF全文

肖圆  郭新丽  宁波 《海洋开发与管理》2022,39(3):101-105

当今世界,国与国之间海洋实力的竞争,已经从最初对海洋资源的竞争变成海洋人才竞争,而海洋教育则是海洋人才的摇篮,逐渐成为教育体系中不容忽视的重要实践。从少数人海洋教育意识的觉醒,再到如今面向普罗大众的社会海洋教育,由海洋教育衍生的知行、创新、问题思维教育模式,成为推动教育思想与教育实践嬗变的活力因素。文章梳理海洋教育思想及教育实践发展的特点,围绕发展过程中存在的优势与不足,提出海洋教育发展的新路径,使海洋教育更好地服务建设“海洋强国”等国家战略。  相似文献   

霞浦核电基地海洋生物放射性本底水平及辐射剂量评价          下载免费PDF全文

付斌  吴春勇  余雯  何建华 《应用海洋学学报》2022,41(3):454-461

为掌握霞浦核电基地海洋生物的放射性本底水平,在其周边50 km范围内采集5类9种海洋生物样品,测量其中的天然放射性核素238U、232Th、226Ra、40K,以及人工放射性核素137Cs、134Cs、90Sr、58Co、60Co、54Mn、110mAg、65Zn的活度浓度并进行辐射剂量评价。结果显示,所有样品中134Cs、58Co、60Co、54Mn、110mAg、65Zn的活度浓度均低于最小可探测活度浓度,238U、232Th、226Ra、40K、137Cs和90Sr的平均活度浓度分别为(0.48±0.48)、(0.86±1.20)、(0.27±0.34)、(74.3±43.0)、(0.023±0.019)、(0.242±0.167) Bq/kg,处于我国食品天然放射性本底水平内。当地公众由于食入海产品所致年有效剂量为55.1 μSv/a,其中137Cs、90Sr所致剂量分别为0.021、0.49 μSv/a;海洋生物所受辐射剂量为0.048~0.276 μSv/h。〖JP2〗当地公众及海洋生物所受辐射剂量均远低于国家标准限值或国际推荐控制值。本次调查为霞浦核电厂运行前海洋生物放射性本底建立了基线数据,并提出了今后海洋生物监测的重点核素,除137Cs、134Cs、90Sr、58Co、60Co、54Mn、110mAg、65Zn,还应增加对3H、14C、131I的监测。  相似文献