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1.
By means of the proposed nonlinear diagnostic dynamic model for the planetary boundary layer (PBL) wind field, an introduction is given to the MOD method for wind prediction. Based on the MOD experiments on the surface wind field over the Northern Pacific Ocean from April to October 1985, it is concluded that the nonlinear diagnostic dynamic model used is better than the linear one. 相似文献
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城市天气预报随着社会的发展有益重要的趋势,而且对服务质量的要求也越来越高,我们采用近期历史资料和天气学分类、特征量分析等方法,建立南宁市大雨以上降水预报工具并形成准自动化的业务系统,是提高预报水平的重要一环,而发展短期、短时预报方法将会时一步改善预报服务质量。 相似文献
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Comparison of Transient Network Brightenings and Explosive Events in the Solar Transition Region 总被引:1,自引:0,他引:1
I analyze the properties of the pulsed emission from the accreting millisecond pulsar SAX J1808.4-3658 in observations of its 1998 April outburst by the Rossi X-Ray Timing Explorer. Pulse phase spectroscopy shows that the emission evolves from a hard spectrum (power law with photon index of 2.39+/-0.06) to a soft spectrum (index of 3.39+/-0.24). This softening is also observable as a phase lag in the fundamental of low-energy photons with respect to high-energy photons. I show that this lag is roughly constant over 10 days of the outburst. I fit these data with a model in which the pulse emission is from a hot spot on the rotating neutron star and the flux as a function of phase is determined in a calculation which includes the effects of general relativity. The energy-dependent lags are very well described by this model. The harder spectra at earlier phases (i.e., as the spot approaches) are the result of larger Doppler-boosting factors that are important for this fast pulsar. Since this model is sensitive to the equatorial speed as an independent parameter and since the spin frequency is known, this offers us a new means of measuring the neutron star radius, which is notoriously difficult to determine. 相似文献
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广州徑流实驗站自1959年建站以来,共布設雨量站点14处。全部站都是用南京水利电力仪表厂仿苏Ⅱ-1型自記雨量計进行測驗的,最初我們对自記雨量計的使用不熟练,发生問題不少,通过这几年来的摸索,积累了一些經驗,茲介紹如下,以供参考。(一) 我站使用的仿苏Ⅱ-1型自記雨量計,每天均 相似文献
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正中学地理课堂教学中有许多案例分析,多是国内外业已引为经典的事例。这些地理事例图文并茂、事实详尽、特征鲜明,是课堂教学中不可或缺的部分。但经典的事例总是与我们的学生有着不能言状的时空距离,仿佛隔着一层纱。所以,能否将学生每天生活着的家乡地域中的日常地理事物或新近发生的乡土地理现象作为教学素材运用到课堂教学中来,以拉近学生对地理案例的现实感知,成为笔者常常思考的一个问题,并也努力在课堂教学中进行了尝试和实践。几年下来,我发现,将乡土地理素材运用到高中地理课堂教学中来并不缺乏契机和知识结合点。笔者把将乡土地理素材融入到高中地理课堂教学的这一教学模式取名为"乡土一刻"。 相似文献
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地热能是一种清洁的可再生能源,用地热能替代高碳能源是减少碳排放的有效途径之一。井下保温管技术是影响地热能开采效率的关键技术之一。本文从保温管的结构、材料、保温材料及制作工艺方面介绍了井下保温管的发展研究现状,指出纳米保温材料与真空油管的融合将是未来的发展趋势,真空纳米保温管是用于深部地热能开采的首选,同时也指出了真空纳米保温管的基础结构因素对保温性能的影响机制是研究的重点,为优化保温管的制作工艺、降本增效提供参考。 相似文献
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The objectives of this study were to measure: (1) Irgarol and GS26575 (major metabolite) during the peak 2004 boating season at selected marinas and reference areas in the Carolinian Zoogeographic Province of the Eastern United States; (2) Irgarol and GS26575 at selected stations during the summer months in the Back Creek/Severn River area in Maryland in 2003 and 2004; and (3) structural and functional characteristics of resident phytoplankton communities concurrently with Irgarol and GS26575 monitoring in Back Creek/Severn River area. Irgarol concentrations from 14 marinas in the Carolinian Province ranged from non-detectable (<1 ng/L) to 85 ng/L; concentrations were less than 16 ng/L at all reference sites. The probability of exceeding the plant 10th centile for Irgarol (251 ng/L) was less than 0.6% for all marinas and 0.01% for all reference areas. These data suggest low ecological risk from Irgarol exposure for both marina and reference areas in the Carolinian Province. Irgarol concentrations ranged from 5 ng/L at the Severn River reference site to 1,816 ng/L in Port Annapolis marina during the two year study. Ecological risk from Irgarol exposure was high for the Port Annapolis marina sites based on a probability of exceeding the plant 10th centile. However, risk was low for Severn River and Severn River reference sites. Functional and structural measures of resident phytoplankton communities in the Back Creek and Severn River did not suggest that these target species are impaired in the Port Annapolis marina area where probabilistic analysis predicted adverse effects from Irgarol exposure. 相似文献