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131.
The paper presents the testing of the possibility of determining the heights of GPS points in the homogeneous field in the
new Croatian Height Reference System (HVRS71) by using the method of height transformation. The testing was made in the area
of Zagreb. As part of the field works, normal orthometric heights of 27 GPS points were determined according to the new height
system, by transferring the benchmark heights using the geometric levelling method, thus obtaining GPS/levelling points of
known ellipsoidal and normal orthometric heights. The GPS/levelling points served as the basis for determining the transformation
models that enabled the computation of normal orthometric heights from ellipsoidal heights of any GPS point in the observed
area. The empirical data used for modelling were reduced undulation dN values of GPS/levelling points. As part of the dN modelling
with parametric functions, the approximation surfaces were obtained on the basis of three polynomials: FN310, FN312 and FN318.
The transformation models were also tested using non-parametric Watson and Loess algorithms. The FN318 and Loess models yielded
the best results. 相似文献
132.
The paper describes a finding of photoautotroph cyanobacteria Synechococcus in deep Adriatic waters during the spring of 2006. The maximum abundance in early May was positioned at 800 m, being of order
of the values referred for the surface waters in the Adriatic Sea. The deep abundance maximum has been associated to the fast
ventilation of deep Adriatic waters, usually occurring during wintertime strong cooling events. Two processes were detected:
(1) deep convection in the South Adriatic Pit (SAP) and (2) density current going downslope. The first process was responsible
for bringing the cyanobacteria down to 600-m depth in the area of convection, and the second one triggered the downslope transport
of the cyanobacteria to the SAP very bottom. The depletion rate of Synechoccocus cyanobacteria in an extremely hostile environment has been computed to equal about 1 month. 相似文献
133.
134.
This paper introduces a new method for simulating large-scale subsurface contaminant transport that combines an Analytic Element Method (AEM) groundwater flow solution with a split-operator Streamline Method for modeling reactive transport. The key feature of the method is the manner in which the vertically integrated AEM flow solution is used to construct three-dimensional particle tracks that define the geometry of the Streamline Method. The inherently parallel nature of the algorithm supports the development of reactive transport models for spatial domains much larger than current grid-based methods. The applicability of the new approach is verified for cases with negligible transverse dispersion through comparisons to analytic solutions and existing numerical solutions, and parallel performance is demonstrated through a realistic test problem based on the regional-scale transport of agricultural contaminants from spatially distributed sources. 相似文献
135.
Based on a large set of arrival times of the Pg phase reported by local and regional stations, we estimate azimuthal anisotropy of the Pg-wave velocity in focal volumes of the upper crust in NW Croatia. The method is based on analyses of the azimuthal dependence
of ratios of cumulative differences of arrival times and travel paths between foci of earthquake pairs, computed for rays
propagating within narrow azimuthal windows. The results clearly indicate the presence of anisotropy of 3.3% with the direction
of fast velocity (approximately NNE-SSW) coinciding with the direction of the maximum tectonic pressure as revealed by 23
available focal mechanisms and previous geological investigations. Although a large part of observed anisotropy can be explained
assuming that focal volumes are pervaded by a system of vertical extensive-dilatancy anisotropy (EDA) cracks aligned under
the influence of local tectonic stress field, there is indication that — to a smaller extent — some role was also played by
alignment of structural features in the region. 相似文献
136.
Summary ?This paper deals with variations and trends in some components of the water balance: the soil water content; evaporation
loss from the soil (from the surface and underlying layers); transpiration; ground water recharge and runoff. These components
are calculated by means of the Palmer procedure. This analysis is based on data from Osijek, Croatia from this century (1900–1995).
Besides the meteorological input parameters necessary for the water balance calculations, i.e. precipitation, temperature
and relative humidity, the pedological characteristics of this area have also been taken into account. Fluctuations have been
considered by means of the 11-year binomial filtered series and linear trends were tested by means of the Mann-Kendall rank
test. For a closer look on the trends of water balance components, a progressive analysis of the time series was performed,
too. The results show a significant increase in potential evapotranspiration and evapotranspiration and decrease in runoff
and soil water content has occurred during the century.
Received February 22, 1999/Revised August 3, 1999 相似文献
137.
Taylor Anderson Suzana Dragićević 《International journal of geographical information science》2020,34(9):1792-1821
ABSTRACT Agent-based models (ABM) are used to represent a variety of complex systems by simulating the local interactions between system components from which observable spatial patterns at the system-level emerge. Thus, the degree to which these interactions are represented correctly must be evaluated. Networks can be used to discretely represent and quantify interactions between system components and the emergent system structure. Therefore, the main objective of this study is to develop and implement a novel validation approach called the NEtworks for ABM Testing (NEAT) that integrates geographic information science, ABM approaches, and spatial network representations to simulate complex systems as measurable and dynamic spatial networks. The simulated spatial network structures are measured using graph theory and compared with empirical regularities of observed real networks. The approach is implemented to validate a theoretical ABM representing the spread of influenza in the City of Vancouver, Canada. Results demonstrate that the NEAT approach can validate whether the internal model processes are represented realistically, thus better enabling the use of ABMs in decision-making processes. 相似文献
138.
P. Milanović 《Environmental Geology》1996,27(2):105-107
Ombla Spring is located on the Adriatic coast near the town of Dubrovnik. The spring discharges at sea level. To eliminate the influence of the tide, a small dam was constructed 50 m downstream of the spring outlet. The spring water overflows the dam crest at an elevation of 2.40 m. Since 1897 the springwater has been used for the water supply for Dubrovnik. 相似文献
139.
The microphysical model with the bulk water parameterization is applied to simulated both contact and deposition nucleation as well as the imersion freezing for unseeded cases and the cases immediately after seeding performed for the cold continental Cb clouds with small cloud droplets. The injection of agent AgI is performed in temperature region between –8°C and –12°C. The four groups of sensitivity experiments are executed.
With 14 Figures 相似文献
a. | The Brownian coagulation of rain drops is the most important contact nucleation mechanism for seeded cases with great amount of rain drops. When cloud droplets mainly contribute to the liquid water content for seeded cases, the Brownian coagulation of cloud droplets is the primary nucleation mechanism while the inertial impact is the less effective contact nucleation mechanism; |
b. | the mutual interdependence of contact and deposition nucleation mechanisms shows that the contact nucleation is more effective for graupel production than the deposition one for the temperature region considered in this model; |
c. | the imersion freezing is the most important mechanism for all cases with significant amount of rain drops. It is more effective than the contact nucleation mechanism in unseeded cases with insufficient number of rain drops; |
d. | the nucleation mechanisms are more sensitive to temperature changes than to pressure changes. |
140.
Petar Milanović 《Environmental Geology》1990,15(1):5-11
The region of eastern Herzegovina and Dubrovnik coastal belt is one of the hydrogeologically and hydrologically most interesting regions of Yugoslavia karst. The main water course in the region is the Trebinjica river, the largest sinking river in Europe. All the poljes in the catchment area are temporary flooded, hydrologically separated, and closed karst entities. Enormous quantities of available water are not evenly disturbed neither in the time nor in the space. The Trebinjica Hydrosystem project uses the basic concept of total water regime organization and its multipurpose utilization. With the construction of seven dams, six artificial reservoirs, six tunnels (with total length, 57 km), and four canals (with total length 74 km) the natural regime of surface and underground waters has been completely changed.As a consequence of water regime disturbance, a lot of changes have been observed in the catchment area: changes in the karst aquifers; local changes of climate conditions; eolic erosion effect; influence on the karst underground and littoral belt; influence on the springs yield; influence on adjacent catchment area; pollution of karst aquifers and influence of storage reservoirs on seismicity—induced seismicity. This article presents influences observed after the first stage of hydrosystem construction. 相似文献