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1.
CARBON DYNAMICS OF WETLAND IN THE SANJIANG PLAIN 总被引:2,自引:0,他引:2
SONG Chang-chun WANG Yi-yong WANG Yue-si YAN Bai-xing WANG De-xuan ZHAO Zhi-chun LOU Yan-jing 《中国地理科学(英文版)》2003,13(3):228-231
1INTRODUCTIONWetlandsplayanimportant roleintheprocessofcar-bonstorage.Thetotalcarbonstoredindifferentkindsofwetlandsisabout15%-35%ofthetotalcarboninthegloballandsoils(POSTetal.,1982;GORHAM,1991).Inaddition,wetlandsaresignificantnaturalsources fortheatmospheric CH4 (MOORE,1994).It isestimatedthatabout110×1012gCH4 originates fromanaerobicdecompositioninthenaturalwetlands,CH4 emission fromthenaturalwetlandsis15%-30%oftheglobalCH4 emission andtheCH4 emission from thepeat land at hi… 相似文献
2.
着重讨论了网络用户经济效益的内涵以及用户的投入量和产出量,并提出了评价网络用户经济效益的指标体系,包括成本降低率,成本利润增长率、产品开发时间约率、市场占有增长率等系列指标。 相似文献
3.
Douglas P. Looze Markus Kasper Stefan Hippler Orhan Beker Robert Weiss 《Experimental Astronomy》2003,15(2):67-88
This paper develops a compensation algorithm based on Linear–Quadratic–Gaussian (LQG) control system design whose parameters
are determined (in part) by a model of the atmosphere. The model for the atmosphere is based on the open-loop statistics of
the atmosphere as observed by the wavefront sensor, and is identified from these using an auto-regressive, moving average
(ARMA) model. The (LQG) control design is compared with an existing compensation algorithm for a simulation developed at ESO
that represents the operation of MACAO adaptive optics system on the 8.2 m telescopes at Paranal, Chile.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
5.
旅游生态效率是反映旅游经济与旅游环境双向效应(bi-effect)的重要判断指标。本文基于非期望产出视角,采用超效率SBM模型,评价了我国东部沿海18个主要滨海旅游城市的旅游生态效率,并分析了其时空演变特征。研究结果表明:(1)中国东部沿海18市滨海旅游生态效率整体呈中等水平,平均值处于0.727~0.894,阶段特征明显,呈现前期平稳发展,中期下降,后期回升的发展趋势;(2)各城市滨海旅游生态效率水平差异显著,分为下行风险型,持续成长型,稳定型和波动型4种发展类型。平均效率值最高为天津,最低为三亚;(3)分解效率均值中纯技术效率较高,规模效率次之,技术进步是影响综合效率的主要因素;(4)投入冗余和非期望产出冗余已经成为阻碍滨海旅游生态效率进步的关键因素。 相似文献
6.
提出了海上浮动软管的三维静态分析模型。在四级海情下,对输送柴油的软管求得了解析解,得出了软管在侧向和垂直方向的偏移及其所受的拉力,认为此时的软管是不安全的。 相似文献
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8.
蔡明华 《中国海洋大学学报(自然科学版)》1995,(4)
介绍一种反馈补偿法修正传感器电桥电路的非线性。提出反馈补偿原理及应用实例,指出用该方法可获得满意的补偿效果。 相似文献
9.
Very high-frequency marine multichannel seismic reflection data generated by small-volume air- or waterguns allow detailed, high-resolution studies of sedimentary structures of the order of one to few metres wavelength. The high-frequency content, however, requires (1) a very exact knowledge of the source and receiver positions, and (2) the development of data processing methods which take this exact geometry into account. Static corrections are crucial for the quality of very high-frequency stacked data because static shifts caused by variations of the source and streamer depths are of the order of half to one dominant wavelength, so that they can lead to destructive interference during stacking of CDP sorted traces. As common surface-consistent residual static correction methods developed for land seismic data require fixed shot and receiver locations two simple and fast techniques have been developed for marine seismic data with moving sources and receivers to correct such static shifts. The first method – called CDP static correction method – is based on a simultaneous recording of Parasound sediment echosounder and multichannel seismic reflection data. It compares the depth information derived from the first arrivals of both data sets to calculate static correction time shifts for each seismic channel relative to the Parasound water depths. The second method – called average static correction method – utilises the fact that the streamer depth is mainly controlled by bird units, which keep the streamer in a predefined depth at certain increments but do not prevent the streamer from being slightly buoyant in-between. In case of calm weather conditions these streamer bendings mainly contribute to the overall static time shifts, whereas depth variations of the source are negligible. Hence, mean static correction time shifts are calculated for each channel by averaging the depth values determined at each geophone group position for several subsequent shots. Application of both methods to data of a high-resolution seismic survey of channel-levee systems on the Bengal Fan shows that the quality of the stacked section can be improved significantly compared to stacking results achieved without preceding static corrections. The optimised records show sedimentary features in great detail, that are not visible without static corrections. Limitations only result from the sea floor topography. The CDP static correction method generally provides more coherent reflections than the average static correction method but can only be applied in areas with rather flat sea floor, where no diffraction hyperbolae occur. In contrast, the average static correction method can also be used in regions with rough morphology, but the coherency of reflections is slightly reduced compared to the results of the CDP static correction method. 相似文献
10.
针对具有外部持续扰动的线性系统,研究前馈-反馈最优控制律的设计问题。给出了最优控制律的存在唯一性条件。并提出了最优控制律的设计算法。利用滤波器解决了前馈控制的物理不可实现问题。仿真结果表明,此算法易于实现,与传统的反馈最优控制相比对抑制外部扰动具有较强的鲁棒性。 相似文献