排序方式： 共有127条查询结果，搜索用时 281 毫秒
101.
邬群勇 王钦敏 周成虎 陈传彬 黄瑞垠 WU Qunyong WANG Qinmin ZHOU Chenghu CHEN Chuanbin HUANG Ruiyin 《地球信息科学学报》2007,9(4):85-88
GML作为一种空间信息的编码、存储和交换格式,已逐渐被接受并广泛使用,为实现空间信息的共享和WebGIS的进一步发展提供了一个强有力的工具;SVG作为一种网络时代的图形文件格式标准,综合了矢量图形、位图图像和纯文本的优点,对网络环境有天然的适应性,代表未来网上图形传输发展的方向,因此,基于GML&SVG的WebGIS研究与应用具有广泛的实用价值和应用前景.文中提出了利用GML进行地理信息的存储和集成,并用SVG实现地理信息的Web显示,操作的开放式WebGIS体系结构和解决方案.且在此基础上,建立了GML&SVG的WebGIS应用系统. 相似文献
102.
地质历史中有无地震？回答是肯定的。现代板块构造机制解决了地震的构造成因,同样地史中的板块运动也必然诱发地震。遗憾的是有关地史中地震（古地震）的报道实在是太少了,究其原因：①不认识地史中的地震记录;②缺乏有效的研究手段和方法;③忽视这一研究领域,或者将地震记录作其他成因解释。因此古地震研究就成了地质调查中的薄弱环节。 相似文献
103.
Onur ?al??kan ?hsan ?i?ek Andreas Matzarakis 《Theoretical and Applied Climatology》2012,107(3-4):417-425
Climate is an important resource for tourism and an equally important element that needs to be included in tourism promotions. This study reveals Bursa’s bioclimatological conditions. These conditions were identified by using physiologically equivalent temperature and a Climate–Tourism–Information–Scheme over 10-day periods and analyzing the mean thermal perception values that emerged. Evaluating bioclimatic conditions and meteorological parameters such as air temperature, duration of sunshine, number of wet days, amount of precipitation, and wind from the perspective of tourism will help people choose the best holiday times depending on their individual needs and circumstances. 相似文献
104.
Carrier phase–based positioning using Global Navigation Satellite System (GNSS) signals can provide centimeter-level accuracy; however, to do so requires robust, continuous tracking of the phase of the received signal. The phase-locked loop is typically the weakest link in GNSS signal processing, with frequent cycle slips and loss of lock occurring at lower signal-to-noise ratios. One way to improve the signal-to-noise ratio is to increase the coherent integration time; however doing so reduces the loop update rate, thereby degrading performance. This paper investigates this trade-off between sensitivity and loop update rate by investigation of the Kalman filter-based tracking loop. It is shown that it is possible to choose an optimal integration time for a given application. A relatively straightforward procedure is given to determine this optimal value. The results are confirmed through real-time kinematic processing of live satellite signals. 相似文献
105.
D. Casas G. Ercilla M. Yenes F. Estrada B. Alonso M. Garc??a L. Somoza 《Marine Geophysical Researches》2011,32(1-2):245-256
The Baraza Slide is located in the northwestern Alboran Sea, western Mediterranean region, between 590 and 830?m water depth, and its morphology, seismic facies and sedimentary structure are analyzed based on multibeam bathymetry and very high to medium resolution single-channel seismic records. During the Pleistocene and Late Quaternary this landslide has undergone repeated slope failures characterized by a succession of two main types of mass movement, the first of the mass-flow type and the second of the slide type. This study also reveals that the western sector of this landslide could still be active. The relatively high slope gradients, a sedimentary column characterized by the presence of under consolidated layers and earthquake shaking related to tectonic activity on the margin are the factors governing the genesis and post-mobility behavior of the Baraza mass movement. The recognition and analysis of these factors suggest that the Baraza Slide should be considered as a geo-hazard in the tectonically active Alboran Sea. 相似文献
106.
This paper applies, for the first time in offshore deepwater, a method based on geographic information systems for seafloor susceptibility assessment as a first approach to marine geohazard mapping in fluid leakage areas (slope instabilities, gas escapes, seabed collapses, pockmarks, etc.). The assessment was carried out in a known seabed fluid-flow province located on the Iberian margin of the Gulf of C??diz, Spain. The method (based on statistical bivariate analysis) creates a susceptibility map that defines the likelihood of occurrence of seafloor features related to fluid flow: crater-like depressions and submarine landslides. It is based on the statistical index (Wi) method (Van Westen in Statistical landslide hazard analysis. ILWIS 2.1 for Windows application guide. ITC Publication, Enschede, pp 73?C84, 1997), in which Wi is a function of the cartographic density of seafloor features on ??factor maps??. The factors selected monitor the seafloor??s capability to store and transfer hydrocarbon gases and gravitational instability triggers: geology-lithology, gas hydrate stability zone thickness (temperature, pressure?Cwater depth and geothermal gradient), occurrence of diapirs, proximity to faults or lineaments, and slope angle of the seafloor. Results show that the occurrence of seafloor features related to fluid flow is highest where the factors ??gas source and storage?? and ??pathways of fluid escape?? converge. This means that they are particularly abundant over diapirs in contourite deposits, in the vicinity of faults, and inside theoretical gas hydrate stability fields thinned by warm undercurrents. Furthermore, the submarine landslides located on the Palaeozoic-Toarcian basement are not related to fluid leakage. This methodology provides helpful information for hazard mitigation in regional selection of potential drill sites, deep-water construction sites or pipeline routes. It is an easily applied and useful tool for taking the first step in risk assessment on a regional scale for vast areas where fluid leakage may be present, the geological model is known, and the geologically hazardous features have already been mapped. 相似文献
107.
Insect outbreaks are major disturbances that affect a land area similar to that of forest fires across North America. The recent mountain pine bark beetle (D endroctonus ponderosae) outbreak and its associated blue stain fungi (Grosmannia clavigera) are impacting water partitioning processes of forests in the Rocky Mountain region as the spatially heterogeneous disturbance spreads across the landscape. Water cycling may dramatically change due to increasing spatial heterogeneity from uneven mortality. Water and energy storage within trees and soils may also decrease, due to hydraulic failure and mortality caused by blue stain fungi followed by shifts in the water budget. This forest disturbance was unique in comparison to fire or timber harvesting because water fluxes were altered before significant structural change occurred to the canopy. We investigated the impacts of bark beetles on lodgepole pine (Pinus contorta) stand and ecosystem level hydrologic processes and the resulting vertical and horizontal spatial variability in energy storage. Bark beetle-impacted stands had on average 57 % higher soil moisture, 1.5 °C higher soil temperature, and 0.8 °C higher tree bole temperature over four growing seasons compared to unimpacted stands. Seasonal latent heat flux was highly correlated with soil moisture. Thus, high mortality levels led to an increase in ecosystem level Bowen ratio as sensible heat fluxes increased yearly and latent heat fluxes varied with soil moisture levels. Decline in canopy biomass (leaf, stem, and branch) was not seen, but ground-to-atmosphere longwave radiation flux increased, as the ground surface was a larger component of the longwave radiation. Variability in soil, latent, and sensible heat flux and radiation measurements increased during the disturbance. Accounting for stand level variability in water and energy fluxes will provide a method to quantify potential drivers of ecosystem processes and services as well as lead to greater confidence in measurements for all dynamic disturbances. 相似文献
108.
Ana??akni?-?atovi?Email author William?A.?Gough 《Theoretical and Applied Climatology》2018,132(1-2):41-54
Climatological observing window (COW) is defined as a time frame over which continuous or extreme air temperature measurements are collected. A 24-h time interval, ending at 00UTC or shifted to end at 06UTC, has been associated with difficulties in characterizing daily temperature extrema. A fixed 24-h COW used to obtain the temperature minima leads to potential misidentification due to fragmentation of “nighttime” into two subsequent nighttime periods due to the time discretization interval. The correct identification of air temperature extrema is achievable using a COW that identifies daily minimum over a single nighttime period and maximum over a single daytime period, as determined by sunrise and sunset. Due to a common absence of hourly air temperature observations, the accuracy of the mean temperature estimation is dependent on the accuracy of determination of diurnal air temperature extrema. Qualitative and quantitative criteria were used to examine the impact of the COW on detecting daily air temperature extrema. The timing of the 24-h observing window occasionally affects the determination of daily extrema through a mischaracterization of the diurnal minima and by extension can lead to errors in determining daily mean temperature. Hourly air temperature data for the time period from year 1987 to 2014, obtained from Toronto Buttonville Municipal Airport weather station, were used in analysis of COW impacts on detection of daily temperature extrema and calculation of annual temperature averages based on such extrema. 相似文献
109.
Christina?FlechsigEmail author Jens?Heinicke Jan?Mrlina Horst?K?mpf Tobias?Nickschick Alina?Schmidt Tomá??Bayer Thomas?Günther Carsten?Rücker Elisabeth?Seidel Michal?Seidl 《International Journal of Earth Sciences》2015,104(8):2087-2105
The Mýtina maar is the first known Quaternary maar in the Bohemian Massif. Based on the results of Mrlina et al. (J Volcanol Geother Res 182:97–112, 2009), a multiparametric geophysical (electrical resistivity tomography, gravimetry, magnetometry, seismics) and geological/petrochemical research study had been carried out. The interpretation of the data has provided new information about the inner structure of the volcanic complex: (1) specification of the depth of post-volcanic sedimentary fill (up to ~100 m) and (2) magnetic and resistivity signs of one (or two) hidden volcanic structures interpreted as intrusions or remains of a scoria cone. The findings at the outer structure of the maar incorporate the (1) evidence of circular fracture zones outside the maar, (2) detection and distribution of volcanic ejecta and tephra-fall deposits at the surface, and (3) indications from electrical resistivity tomography and gravity data in the area between the Mýtina maar and ?elezná h?rka scoria cone, interpreted as a palaeovalley, filled by volcaniclastic rocks, and aligned along the strike line (NW–SE) of the Tachov fault zone. These findings are valuable contributions to extend the knowledge about structure of maar volcanoes in general. Because of ongoing active magmatic processes in the north-east part of the Cheb Basin (ca. 15–30 km north of the investigation area), the Mýtina maar-diatreme volcano and surroundings is a suitable key area for research directed to reconstruction of the palaeovolcanic evolution and assessment of possible future hazard potential in the Bohemian Massif. 相似文献
110.
Morpho-tectonic evolution of the Marmara Sea inferred from multi-beam bathymetric and seismic data 总被引：1，自引：6，他引：1
Erkan?Goka?anEmail author Timur?Usta?mer Cem?Gazio?lu Zeki?Ya?ar?Yucel Kurultay??ztürk Hüseyin?Tur Berkan?Ecevito?lu Bu?ser?Tok 《Geo-Marine Letters》2003,23(1):19-33
In an initial stage, the Sea of Marmara developed as a graben and, in due course, considerable volumes of sediments were deposited in this basin. Before 200 ka, a new fault (New Marmara Fault) cutting through the whole basin developed, which postdated large sub-marine land sliding in the western part of the basin. This mass movement created the Western Ridge. The initiation of this strike-slip fault indicates that the extensional stress regime was replaced by a new, shearing stress field. In the eastern part of the Marmara Basin, the New Marmara Fault consists of two branches. The northern one replaces the normal faulting at the bottom of the northeastern slope of the basin. As a result, this slope has been rejuvenated. The southern branch is located along the central axis of the basin, forming the major extension of the North Anatolian Fault Zone within the region. Two restraining bends were formed because of the counterclockwise rotation of that part of the Anatolian Block. This resulted the uplifting of the Eastern Ridge and the formation of the positive flower structure within the Tekirdag Basin. The establishment of the compressional regime around the Sea of Marmara also resulted in the northwest–southeast shortening of the initial Marmara Basin. 相似文献