Prediction of input energy spectrum: attenuation models and velocity spectrum scaling          下载免费PDF全文

F. S. Alıcı  Halûk Sucuoğlu 《地震工程与结构动力学》2016,45(13):2137-2161

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Neural network prediction of bed material load transport     

Bimlesh Kumar 《水文科学杂志》2013,58(5):956-966

Abstract

Bed material load, which comprises bed load and suspended load, has been extensively studied in the past few decades and many equations have been developed, but they differ from each other in derivation and form. If a process can be related to various flow conditions on a general basis, a proper understanding of bed material load movement can be ascertained. As the process is extremely complex, obtaining a deterministic or analytical form of it is too difficult. Neural network modelling, which is particularly useful in modelling processes about which knowledge of the physics is limited, is presented here as a complimentary tool for modelling bed material load transport. The developed model demonstrated a superior performance compared to other traditional methods based on different statistical criteria, such as the coefficient of determination, Nash-Sutcliffe coefficient and discrepancy ratio. The significance of the different input parameters has been analysed in the present work to understand the influence of these parameters on the transport process.

Editor D. Koutsoyiannis

Citation Kumar, B., 2012. Neural network prediction of bed material load transport. Hydrological Sciences Journal, 57 (5), 956–966.  相似文献   

基于等效单自由度体系的结构地震输入能量的研究     

杜敏  林玮  郭晓云 《地震工程与工程振动》2011,31(3):77-82

通过对多自由度体系结构在地震作用下的能量分析,考虑地震动因素和结构自身特性,提出一种框架结构地震总输入能量的简化求解方法.实例计算结果表明:基于等效单自由度体系来估计多自由度体系的地震总输入能,是一种计算简便且较为准确的方法.  相似文献   

江西鄱阳湖地区土壤酸化与人为源氮的关系   总被引：4，自引：0，他引：4  

文帮勇  杨忠芳  侯青叶  杨晓燕  尹国胜  衷存堤 《现代地质》2011,25(3):562-568

江西鄱阳湖地区是我国土壤酸化严重的地区之一,对比研究区多目标区域地球化学调查与第二次土壤普查资料发现,研究区土壤酸化趋势严重,强酸性土壤占研究区面积比例由58.22%上升到78.44%;赣江、抚河水系入湖区和饶河流域表层土壤酸化明显。研究区因施肥、大气干湿沉降和灌溉输入到农田的氮素分别为123.84 kg.hm-.2a-1、74.13 kg.hm-.2a-1、11.02 kg.hm-.2a-1。研究区因人为氮带入农田的H+为18.67 kmol.hm-.2a-1。化肥氮是引起土壤酸化的主控因素,氮沉降也是影响土壤酸化的主要因素之一。土壤pH与氮含量呈较差负相关,说明土壤中的有机氮对土壤酸化作用有限,增施有机肥和复合肥,适当减少氮肥,特别是铵态氮肥的比例,可以补充盐基物质的相对不足,达到缓解土壤酸化的作用。土壤pH与钙含量呈极显著正相关,适量增施含钙物质可以有效地防止表层土壤酸度降低。  相似文献   

国外海洋渔业准入制度的实践分析   总被引：1，自引：0，他引：1  

唐建业 《广东海洋大学学报》2011,31(2):1-6

捕捞生产的准入是进行海洋渔业资源有效管理的必要条件。综合相关国家渔业管理发展过程,准入制度可能有三种类型:初步准入制度、投入型准入制度和产出型准入制度。准入的对象涉及渔船、渔获及渔具等。从实践经验看,在渔船数量扩展前,建立有效的准入制度的成功概率相对较大;如果现有的捕捞能力已经远超过渔业资源的承载能力时,投入型准入制度虽然还是十分重要,但在削减捕捞能力方面作用有限;产出型准入制度在一些国家的渔业实践中取得了一定的成功,但存在着诸如总可捕量控制、监测与执法等方面的问题。总体上,捕捞权利与捕捞许可证流转等是实施准入制度过程中应给予关注的两个事项。我国可在现行的捕捞许可证与船网工具指标制度的基础上完善我国投入型准入制度,将渔具纳入管理;在条件成熟的情况下,可适当过渡实施产出型准入制度。  相似文献   

A simplified approach to design fuzzy logic controller for an underwater vehicle   总被引：1，自引：0，他引：1  

K. Ishaque  S.S. Abdullah  S.M. Ayob  Z. Salam 《Ocean Engineering》2011,38(1):271-284

Fuzzy logic controller (FLC) performance is greatly dependent on its inference rules. In most cases, the more rules being applied to an FLC, the accuracy of the control action is enhanced. Nevertheless, a large set of rules requires more computation time. As a result, an FLC implementation requires fast and high performance processors. This paper describes a simplified control scheme to design a fuzzy logic controller (FLC) for an underwater vehicle namely, deep submergence rescue vehicle (DSRV). The proposed method, known as the single input fuzzy logic controller (SIFLC), reduces the conventional two-input FLC (CFLC) to a single input FLC. The SIFLC offers significant reduction in rule inferences and simplifies the tuning process of control parameters. The performance of the proposed controller is validated via simulation by using the marine systems simulator (MSS) on the Matlab/Simulink^® platform. During simulation, the DSRV is subjected to ocean wave disturbances. The results indicate that the SIFLC, Mamdani and Sugeno type CFLC give identical response to the same input sets. However, an SIFLC requires very minimum tuning effort and its execution time is in the orders of two magnitudes less than CFLC.  相似文献   

基于投入产出模型的旅游消费对经济增长的动态影响研究     

周文丽 《地域研究与开发》2011,30(3):79-83,88

基于投入产出模型,利用中国《2002年部门投入产出表》,定量测度了1997—2007年间我国城乡居民国内旅游消费对国民经济及各部门产出增长的贡献率及其变化,并提出相应的建议。研究结论:(1)城镇居民国内旅游消费对经济增长的贡献在上升,农村居民的贡献在下降,总体国内旅游消费对经济增长的贡献在下降。(2)城乡居民国内旅游消费对各产业产出增长贡献从大到小依次为:旅游业、住宿和餐饮业、交通仓储和邮政业、金融保险业、其他服务业、房地产业和批发零售业。(3)我国旅游业发展八分靠国内旅游,二分靠国际旅游;国内旅游消费结构中,非基本消费比重较小,亟待提高。  相似文献   

Varved sediments of Lake Yoa (Ounianga Kebir,Chad) reveal progressive drying of the Sahara during the last 6100 years   总被引：1，自引：0，他引：1  

Pierre Francus  Hans von Suchodoletz  Michael Dietze  Reik V. Donner  Frédéric Bouchard  Ann‐Julie Roy  Maureen Fagot  Stefan Kröpelin 《Sedimentology》2013,60(4):911-934

The sedimentological and geochemical properties of a 7·47 m long laminated sequence from hypersaline Lake Yoa in northern Chad have been investigated, representing a unique, continuous 6100 year long continental record of climate and environmental change in the eastern Central Sahara. These data were used to reconstruct the Mid to Late Holocene history of this currently hyper‐arid region, in order to address the question of whether the Mid Holocene environmental transition from a humid to a dry Sahara was progressive or abrupt. This study involved a suite of analyses, including petrographic and scanning electron microscope examination of thin sections, X‐ray diffraction, X‐radiography, granulometry, loss on ignition and magnetic susceptibility. The potential of micro‐X‐ray fluorescence core scanning was tested at very high resolution. Detailed microscopic investigation revealed the sedimentary processes responsible for the formation of the fine laminations, identified the season during which they were formed, and confirmed their annually rhythmic nature. High‐resolution X‐ray fluorescence core scanning allowed the distinction of each individual lamination over the entire record, opening new perspectives for the study of finely laminated sediment sequences. Geochemical and mineralogical data reveal that, due to decreasing monsoon rainfall combined with continuous and strong evaporation, the hydrologically open and fresh Mid Holocene Lake Yoa slowly evolved into the present‐day hypersaline brine depleted in calcium, which has existed for about the past 1050 years. During the oldest part of the investigated period, Lake Yoa probably contained a permanently stratified lower water column that was nevertheless disrupted relatively frequently by mixing events. Deep‐water anoxia became more stable because of increased salinity‐driven density stratification. In parallel, the sediment grain‐size proxies record a progressive increase of aeolian input in the course of the last 6100 years. Altogether, all geochemical and sedimentological indicators point to a progressive drying of the eastern Central Sahara, strengthening previous conclusions based on palaeoecological indicators.  相似文献   

Impact of Climate Warming in the Past 20 Years on Agriculture in Different Regions of China     

Liu Yingjie  Lin Erda 《气候变化研究进展》2008,4(00):51-55

 Based on the China Rural Statistical Yearbook of 1984-2003 published by State Statistics Bureau, and the annual temperature in the same period, impacts of temperature change, agricultural input, and planting area on grain production were analyzed for different regions of China during the last 20 years. The results show that the main characteristic of climate warming has obviously promoted the increase of grain yield in Northeast China, but to some extent suppressed it in North China, Northwest China and Southwest China, and shown no obvious effect on it in East China and Central-South China. The increase in agricultural input facilitated the grain production obviously in various regions in the early stage of the past 20 years, but showed no obvious effect in the late stage. The continuous reduction in sown area had a significant negative effect on the grain production in East China and Central-South China.  相似文献   

Basin and crustal velocity structure models for the simulation of strong ground motions in the Kinki area,Japan     

Tomotaka Iwata  Takao Kagawa  Anatoly Petukhin  Yoshihiro Ohnishi 《Journal of Seismology》2008,12(2):223-234

We constructed a prototype of the basin and crustal structure model for the Kinki area, southwest of Japan, for the simulation of strong ground motions of hypothetical crustal and subduction earthquakes. We collected results of the deep seismic velocity profiles obtained by the reflection experiments and seismic imaging results, which were conducted in the Kinki area. The obtained profiles give underground velocity structures of the crust, from the surface to the subducting slab. We also gather the basin velocity structure information of the Osaka, Kyoto, Nara, and Ohmi basins. To examine the applicability of the constructed velocity structure model to the ground motion simulation, we simulated waveforms of an intermediate size event occurred near the source area of the hypothetical subduction earthquakes. Simulated ground motions using the basin and crustal velocity structure model are fairly well reproducing the observations at most of stations, and the constructed basin and crustal velocity structure model is applicable for the long-period ground motion simulations.  相似文献