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1.
Internal waves play a crucial role in ocean mixing, and density perturbation and energy flux are essential quantities to investigate the generation and propagation of internal waves. This paper presents a methodology for calculating density perturbation and energy flux of internal waves only using a velocity field that is based on linearized equations for internal waves. The method was tested by numerical simulations of internal waves generated by tidal flowing over a Gaussian topography in a stratified fluid. The density perturbations and energy fluxes determined using our method that only used velocity data agreed with density perturbations and energy fluxes determined by the equation of state based on temperature data. The mean relative error (MRE) and root mean square error (RMSE) between the two methods were lower than 5% and 10% respectively. In addition, an experiment was performed to exam our method using the velocity field measured by Particle Image Velocimetry (PIV), and the setup of the experiment is consistent with the numerical model. The results of the experiments calculated by the methods using PIV data were also generally equal to those of the numerical model. 相似文献
2.
Huaming Yu Lu Wang Liang Kuang Haiqing Yu Yuchen Sun Yuhuan Qu Xin Wu 《中国海洋大学学报(英文版)》2016,15(2):209-218
Based on the finite-volume coastal ocean model(FVCOM),a three-dimensional numerical model FVCOM was built to simulate the ocean dynamics in pre-dam and post-dam conditions in Bachimen(BCM).The domain decomposition method,which is effective in describing the conservation of volume and non-conservation of mechanical energy in the utilization of tidal energy,was employed to estimate the theoretical tidal energy resources and developable energy resources,and to analyze the hydrodynamic effect of the tidal power station.This innovative approach has the advantage of linking physical oceanography with engineering problems.The results indicate that the theoretical annual tidal energy resources is about 2×10~8 k Wh under the influence of tidal power station;Optimized power installation is confirmed according to power generation curve from numerical analysis;the developable resources is about 38.2% of theoretical tidal energy resources with the employment of one-way electricity generation.The electricity generation time and power are 3479 hours and 2.55×10~4 KW,respectively.The power station has no effect on the tide pattern which is semi-diurnal tide in both two conditions,but the amplitudes of main constituents apparently decrease in the area near the dam,with the M_2 decreasing the most,about 62.92 cm.The tidal prism shrinks to 2.28×10~7 m~3,but can still meet the flow requirement for tidal power generation.The existence of station increases the flow rate along the waterway and enhances the residual current.There are two opposite vortexes formed on the east side beside the dam of the station,which leads to pollutants gathering. 相似文献
3.
The wind-sea and swell climates in the China Seas are investigated by using the 27-yr Integrated Ocean Waves for Geophysical and other Applications(IOWAGA)hindcast data.A comparison is made between the significant wave height from the IOWAGA hindcasts and that from a jointly calibrated altimetry dataset,showing the good performance of the IOWAGA hindcasts in the China Seas.A simple but practical method of diagnosing whether the sea state is wind-sea-dominant or swell-dominant is proposed based on spectral partitioning.Different from the characteristics of wind-seas and swells in the open ocean,the wave fields in the enclosed seas such as the China Seas are predominated by wind-sea events in respect of both frequencies of occurrences and energy weights,due to the island sheltering and limited fetches.The energy weights of wind-seas in a given location is usually more significant than the occurrence probability of wind-sea-dominated events,as the wave energy is higher in the wind-sea events than in the swell events on average and extreme wave heights are mostly related to wind-seas.The most energetic swells in the China Seas(and other enclosed seas)are‘local swells’,having just propagated out of their generation areas.However,the swells coming from the West Pacific also play an important role in the wave climate of the China Seas,which can only be revealed by partitioning different swell systems in the wave spectra as the energy of them is significantly less than the‘local swells’. 相似文献
4.
由于当前缺乏有效的能源开采和加工场地精细化遥感探测方法和高精度的数据产品,全国尺度的能源开采和加工场地时空分布规律的认识仍显不足。本研究基于高分辨率遥感影像、土地利用/覆盖数据、网络爬虫数据、OSM地图数据和环境专题数据等信息,发展了基于多源数据融合和专家知识参与获取的能源开采和加工场地遥感识别和精细化制图的技术方法,研发了1990、2000、2010和2020年共4期的中国能源开采和加工场地分布数据产品及2010—2020年场地植被恢复信息数据产品,作为中国土地利用/覆盖变化数据的组成部分（CLUD-Mining）。CLUD-Mining具有较高的质量和可靠性,数据产品平均精度为91.75%;中国能源开采和加工场地开发建设的面积呈现先增长后减少的发展趋势,1990—2010年,面积增长速度从55.22 km2/a上升到95.51 km2/a,而2010—2020年呈现负增长,平均每年减少27.28 km2;此外,2010—2020年场地植被恢复面积达746.76 km2,主要集中在华北区和西南区;中国能源开采和加工场地分布格局逐渐由东部地区向西部地区转移。本研究对提升中国能源开采和加工场地时空分布特征的认识具有重要意义,可为场地污染治理和生态修复提供重要的数据基础。 相似文献
5.
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????????????2004~2007???GPS??????????????溯??????????????????????????????????????????????μ????????????????????????????????????????????????????????????????ε????????????????????嶫????????????????????????????????б??κ????????????????????????????2008??????????????????????????θ?????????????????????????????????????ж??????????????????????????????????????-????????????????????????-?????????????????ο??????????????????????????????????????????θ?????????????????????????й?? 相似文献
6.
A transition from wood fuel to LPG and its impact on energy conservation and health in the Central Himalayas, India 总被引：1，自引：1，他引：0
Sunil NAUTIYAL 《山地科学学报》2013,10(5):898-912
The aim of the study was to evaluate the impacts of the transition from wood fuel to Liquefied Petroleum Gas(LPG) from energy use and health perspectives along an altitudinal gradient(viz.,lower altitude;middle altitude;and higher altitude) of the Central Himalayas.Empirical field study and questionnaire based survey was conducted forobtaining the data.A total of 20 households from each altitude were selected for obtaining reliable information on the actual quantity of fuelwood consumed.Of the 20 households,five households each based on the family size i.e.,small families(<4 members),medium(5-8 members) and large(>9 members) from all the altitudinal regions were selected.This was followed by an administration of a questionnaire on the quantity of fuelwood consumed.After the completion of the questionnaire survey,the data was validated using a weighted survey for the randomly selected households for obtaining precise information on the actual quantity of fuelwood consumed.Energy analysis is done with respect to the time spent on fuelwood collection and energy value of burning of per kg of fuelwood.Study indicates that declining biomass requirement from forests contributes significantly towards energy conservation,also has positive impact on human health.Per capita annual energy expenditure on collection of fuelwood is 752 MJ which is higher than any other activity in villages of Central Himalaya.The LPG substitution has contributed to energy saving which is equivalent to 2976-3,742 MJ per capita per year in middle and lower altitudes respectively.In the higher altitude the energy saving is calculated to be about 257 MJ per capita per year.Replacing fuelwood with LPG has made positive impact on society in terms of improving the health while reducing diseases that are caused due to indoor air pollution. 相似文献
7.
为研究近断层不同区域地震动工程特性与时频特征,考虑近断层地震动方向性效应、滑冲效应、上盘效应等特性与断层类型的关系,基于PEER强震数据库,选取台湾集集（Chi-Chi）地震作为研究对象,依据断层破裂带与地震动观测台站的相对位置关系,将其近断层地震动划分为破裂前方区域（RFR）、断层上盘区域（HWR）、断层下盘区域（FWR）及破裂后方区域(RBR)4类,对比分析近断层不同空间地震动的三要素特性,并利用希尔伯特-黄变换（HHT）进一步分析其能量在时频分布上的差异。结果表明：1）近断层不同区域地震动PGA、PGV、PGD及PGV/PGA具有显著差异,给结构地震响应带来极大影响;2）RFR区域地震动呈显著的长周期效应,RBR区域地震动具有高频大幅值特点,HWR区域和FWR区域地震动同时具有高频大幅值特点和显著长周期效应;3）在时频域内,RFR、HWR、FWR、RBR区域地震动能量高值都主要集中在0~5.2 Hz的中低频段,其中HWR区域的地震动最大瞬时能量最大,RFR区域的地震动最大瞬时能量最小。 相似文献
8.
《中国海洋湖沼学报》2017,(6)
Recent satellite altimeter observations have indicated that internal tides(ITs) from the Luzon Strait(LS) propagate more than 2 500 km into the Western Pacific(WP). This study used a high-resolution three-dimensional numerical model to reproduce and examine the ITs radiation process. The propagation of diurnal and semidiurnal ITs showed dif ferent patterns and variations. Diurnal ITs with lower frequency were af fected more by the earth's rotation and they were bent more toward the equator than semidiurnal ITs. ITs phase speeds are functions of latitude and diurnal ITs showed greater distinctions of phase speeds during propagation. For M_2 ITs, the wavelength remained nearly unchanged but the beam width increased significantly during propagation away from the LS. For diurnal ITs(K_1 and O_1), the wavelength decreased noticeably with latitude, while the beam width varied little during propagation because of blocking by land. Baroclinic energy was also examined as a complement to satellite results reported by Zhao(2014). The magnitude of the generated baroclinic energy flux reduced remarkably within 300 km from the generation site but it then decayed slowly when propagating into abyssal sea. Baroclinic energy of diurnal ITs was found to dissipate at a slower rate than semidiurnal ITs along the main propagation path in the WP. 相似文献
9.
《中国地理科学(英文版)》2020,(3)
The impact of human carbon emissions on climate has generated widespread global concern. We selected 24 countries as research objects and analysed the changes in carbon emissions in different countries between the establishment of emission reduction actions in 1990 and 2014. Then, we selected 19 factors representing four categories(economy, population, technology and energy) to explore the key factors that led to changes in carbon dioxide(CO_2) emissions in different countries. Emission reduction actions since 1990 did not lead to marked improvements, and only five countries(Russia, Germany, the United Kingdom, Italy and France) achieved reductions in carbon emissions. The factors that influenced CO_2 emissions varied among countries. In most developing countries, reductions in CO_2 emissions were caused by reductions in poverty and inherent natural conditions. Moreover, the extent of influence of a given factor on CO_2 emissions differed among countries. The global economic crisis may cause similar fluctuations in CO_2 emissions in many countries. Adjustments to energy and industrial structures are the main reason for the reduction in carbon emissions, whereas economic growth and urbanization are the two major contributors to the growth of carbon emissions. According to historical carbon emissions data, a green energy revolution must be implemented to address global climate change and ensure the sustainable development of human societies. 相似文献
10.
Rockfall poses a great threat to buildings and personal security. To understand the dynamic characteristics of rockfalls is a prerequisite for disaster prevention and assessment. Models for rockfalls in different forms are established based on the theory of rigid body motion. The equivalent velocity considering the rotational effect is determined by the energy ratio. Besides, considering plastic deformation and nonlinear hardening, the maximum impact force is estimated based on the Hertz contact theory. Then, a case study is carried out to illustrate the applicability of the model and sensitive analyses on some affecting parameters are also made. Calculation results show that the maximum impact force increases with the increasing of incident velocity, angle and slope gradient reflected by the changing of energy ratio. Moreover, the model for the estimation of maximum impact force is validated by two different scales of experiments and compared with other theoretical models. Simulated maximum impact forces agree well with the experiments. 相似文献
11.
1998-2002年中国地表太阳辐射的时空变化分析 总被引：2，自引：0，他引：2
地表太阳辐射是陆气能量交换过程中重要的物理参数和生态参数,利用卫星数据反演地表太阳辐射对于全面认识地表太阳辐射空间差异性和年际变化特征具有重要的意义。本文利用GMS-5静止气象卫星数据反演了中国区域1998-2002年地表太阳辐射值,在此基础上分析了我国地表太阳辐射的时空分布特征。结果表明:(1)青藏高原的地表太阳辐射最大,川黔地区最小,都位于北纬22~35°这一带除川黔地区外,地表太阳辐射从东向西增强,西部随纬度升高而减小,东部以长江流域最小,向南北增加,西南最大,北部次之,至东北地区随纬度升高而减小(2)各月地表太阳辐射量分布复杂,最小值都出现在12月,但最大值出现时间受雨季影响很大,珠江、长江一带主要在雨季过后的7月,华北、东北和青藏高原主要出现在雨季前的6月及5月,西南地区则在季风雨季前的4-5月(3)5年来东部沿海地区地表太阳辐射增加了13.71%(+4.37W/m2·a),西藏高原地区地表太阳辐射减少了9.31%(-3.47W/m2·a),全国地表太阳辐射平均减少了0.84%(-0.27W/m2·a)。 相似文献
12.
《山地科学学报》2020,17(7):1541-1552
Boulder/rock mass movements generate ground vibrations that can be recorded by geophone networks. Generally, there are two methods applied to rockfall trajectory reconstruction or rockfall seismic localization. One method uses seismic wave arrival times and is achieved by minimizing the differences in signal arrival times between multiple stations by grid map searching. The other method uses seismic polarization and is achieved by calculating eventsource back azimuths from the seismic polarizations of rockfall signals. In this study, we proposed the use of an overdetermined matrix for joint localization based on the polarization method. The overdetermined matrix considers the contributions of all geophones in the network, and at each geophone is assigned a different weight according to the recorded signal qualities and the reliability of the calibrated back azimuths. This method shows a great advantage relative to the case in which only two sensors are employed. Besides, we suggested three marker parameters for proper frequency band selection in back azimuth calculations: energy, rectilinearity, and a special permanent frequency band(SPF). We found that the back azimuths calculated with energy and an SPF are generally close to the real back azimuths measured in the field, while the SPF is limited by seismic attenuation due to a long-distance propagation. The localization results of rockfalls were validated by using field camera videos and in situ calibrations. Three typical cases and 43 artificially released rockfalls are presented in this paper. The proposed method provides an interesting way to locate rockfall events and track rockfall trajectories and avoids the difficulties of obtaining accurate arrival times, as required by the arrival times method. 相似文献
13.
In 2008, a green tide broke out before the sailing competition of the 29th Olympic Games in Qingdao. The causative species
was determined to be Enteromorpha prolifera (Ulva prolifera O. F. Müller), a familiar green macroalga along the coastline of China. Rapid accumulation of a large biomass of floating
U. prolifera prompted research on different aspects of this species. In this study, we constructed a nonnormalized cDNA library from the
thalli of U. prolifera and acquired 10 072 high-quality expressed sequence tags (ESTs). These ESTs were assembled into 3 519 nonredundant gene groups,
including 1 446 clusters and 2 073 singletons. After annotation with the nr database, a large number of genes were found to
be related with chloroplast and ribosomal protein, GO functional classification showed 1 418 ESTs participated in photosynthesis
and 1 359 ESTs were responsible for the generation of precursor metabolites and energy. In addition, rather comprehensive
carbon fixation pathways were found in U. prolifera using KEGG. Some stress-related and signal transduction-related genes were also found in this study. All the evidences displayed
that U. prolifera had substance and energy foundation for the intense photosynthesis and the rapid proliferation. Phylogenetic analysis of
cytochrome c oxidase subunit I revealed that this green-tide causative species is most closely affiliated to Pseudendoclonium akinetum (Ulvophyceae). 相似文献
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16.
Rainfall and runoff energy results in soil erosion. This paper presents new the concepts of rainfall and runoff energy and analyzes the relationship of rainfall energy and runoff energy with sediment transport based on the conversion theory of kinetic and potential energy using artificial rainfall and mechanical calculation. The results show that the ratio of sediment detachment in sloping fallow overland flow increases with the slope gradient, rainfall energy and runoff energy, while the sediment detachment ratio under raindrop impact are significantly higher than those under no raindrop impact. The sediment concentration increases with the slope gradient and rainfall energy; when the slope gradient and rainfall energy are constant, the sediment concentration decreases as the runoff energy increases. Rainfall disturbance coefficients have a logarithmic correlation with the rate of rainfall energy and runoff energy. On the same slope gradient, when the rainfall energy is constant, the disturbance coefficient decreases as the runoff energy increases, while when the runoff energy is constant, the disturbance coefficient increases as the rainfall energy increases. Rainfall energy results in sediment detachment, and runoff energy is the transportation for erosion sediment. This showed that rainfall energy and runoff energy are important in the sediment detachment and transportation of shallow overland flow. 相似文献
17.
探讨了太阳能、振动能和气流能等3种潜在的环境能量及其利用方法。这些方法可有效解决传感器网络节点需要足够持续的能量而传统的电池供能方式不能满足的实际问题。 相似文献
18.
Mountainous areas have been long recognized as particularly important for the planet and sustainable mountain development is a global priority. In order to improve the socioeconomic development perspectives of mountain societies, efficient and well-targeted energy strategies should be formed. An important step towards this direction is adequate understanding of local conditions and specific features that affect energy sector. This procedure allows the inclusion of "locality" in energy planning and so, decentralized energy production is facilitated. The present study attempts to determine the particular energy identity of mountainous areas. Greece, which is the second most mountainous country in the EU, has been selected as a case study. Essential features of the mountainous space have been selected, namely altitude, inclination, remoteness, lack of productive activities, old buildings/vernacular architecture, in order to explore their interrelation with the energy sector. Based on literature review and research findings the interaction between mountainous character and energy is outlined. Therefore, a framework of the characteristics of mountain energy identity is composed, which can provide support to the formation of specialized energy policy for mountainous areas. Some of the main findings of the present study include the significantly increased energy loads of mountainous areas, the abundance of renewable energy potential in high – altitude areas, the vulnerability of mountain societies to energy poverty and the difficulties in sitting energy projects in the restricted usable space of mountains. Since the literature regarding mountains and energy is rather poor the present paper aspires to be a step towards highlighting the importance of energy issues for mountain areas and societies. By determining the features of mountain energy identity energy planning in high – altitude areas and so, helping make energy planning more effective, such research works can be parts of sustainable development strategies for mountainous areas. 相似文献
19.
采用重力异常数据,在频率域内通过Parker-Oldenburg反演算法计算南海及邻区的莫霍面深度。通过EGM2008重力场模型联合GOCE重力场模型,计算研究区的自由空气重力异常;通过重力场分离,得到莫霍面起伏引起的重力异常,用于反演莫霍面深度。计算结果与地震剖面计算的莫霍面深度结果平均偏差1.59 km,标准偏差1.9 km。结果表明,南海及邻区的莫霍面深度分布具有明显的区域化构造特征。 相似文献
20.
城市作为人类活动的重要场所,消耗着大量的物资与能源。实现城市的低碳可持续发展对于促进节能减排,保护环境具有重要意义。目前欧盟主要采用推广可再生能源,调节能源价格,改善建筑材质,降低消耗等多种方式推进城市的低碳绿色转型。但各种能源使用与消耗方式缺乏整体全面分析,不利于指定决策与宣传推广。为此,欧盟启动了对于城市的综合能源生产与消费的分析研究项目。该项目主要通过城市三维模型CityGML,实现对于城市建筑模型、能源管网设施,以及能源消耗的标准化数据管理,并通过CityGML自带的应用领域扩展模块实现对于能源消耗模拟所须数据的支持。在统一数据格式的基础上,实现与专业能源分析软件(Energy Plus,Trnsys等)的数据对接,并将分析结果通过CityGML标准实现共享与可视化。该项目以瑞典斯德哥尔摩,瑞典日内瓦等欧洲绿色能源城市为代表,通过将电力、地热能、太阳能等多种能源进行经济、排放分析,结合建筑物的散热,消耗等多种因素,分析各种能源政策可能会产生的环境、经济、人文影响,从而为支持欧洲城市的可持续发展。本文对IntegrCity项目的研究内容、预期成果、组织方式进行了介绍,并总结了基于CityGML的智慧城市的研究方法与可视化策略。这对于我国城市的发展具有促进意义。 相似文献