A generalization of the fractal/facies model     

Fred J. Molz  Tomasz J. Kozubowski  Krzysztof Podgórski  James W. Castle 《Hydrogeology Journal》2007,15(4):809-816

In order to generalize the fractal/facies concept, a new stochastic fractal model for ln(K) increment probability density functions (PDFs) is presented that produces non-Gaussian behavior at smaller lags and converges to Gaussian at larger lags. The model is based on the classical Laplace PDF. The new stochastic fractal family is called fractional Laplace motion (fLam) having stationary increments called fractional Laplace noise (fLan). This fractal is different from other fractals because the character of the underlying increment PDFs changes dramatically with lag size, which leads to lack of self-similarity. Data also appear to display this characteristic. In the larger lag size ranges, approximate self-affinity does hold. The basic field procedure for further testing of the fractional Laplace theory is to measure ln(K) increment distributions along transects, calculate frequency distributions from the data, and compare results to appropriate fLan family members. The variances of the frequency distributions should also change with lag size (scale) in a prescribed manner. There are mathematical reasons such as the geometric central limit theorem, for surmising that fLam/fLan may be more fundamental than other approaches that have been proposed for modeling ln(K) frequency distributions.  相似文献   

ADCN: An anisotropic density‐based clustering algorithm for discovering spatial point patterns with noise          下载免费PDF全文

Gengchen Mai  Krzysztof Janowicz  Yingjie Hu  Song Gao 《Transactions in GIS》2018,22(1):348-369

Density‐based clustering algorithms such as DBSCAN have been widely used for spatial knowledge discovery as they offer several key advantages compared with other clustering algorithms. They can discover clusters with arbitrary shapes, are robust to noise, and do not require prior knowledge (or estimation) of the number of clusters. The idea of using a scan circle centered at each point with a search radius Eps to find at least MinPts points as a criterion for deriving local density is easily understandable and sufficient for exploring isotropic spatial point patterns. However, there are many cases that cannot be adequately captured this way, particularly if they involve linear features or shapes with a continuously changing density, such as a spiral. In such cases, DBSCAN tends to either create an increasing number of small clusters or add noise points into large clusters. Therefore, in this article, we propose a novel anisotropic density‐based clustering algorithm (ADCN). To motivate our work, we introduce synthetic and real‐world cases that cannot be handled sufficiently by DBSCAN (or OPTICS). We then present our clustering algorithm and test it with a wide range of cases. We demonstrate that our algorithm can perform equally as well as DBSCAN in cases that do not benefit explicitly from an anisotropic perspective, and that it outperforms DBSCAN in cases that do. Finally, we show that our approach has the same time complexity as DBSCAN and OPTICS, namely O(n log n) when using a spatial index and O(n²) otherwise. We provide an implementation and test the runtime over multiple cases.  相似文献   

Statistical modelling of the main features of the <Emphasis Type="Italic">Artemisia</Emphasis> pollen season in Wrocław,Poland, during the 2002–2011 time period     

Anetta?Drzeniecka-Osiadacz  Justyna?KrynickaEmail author  Ma?gorzata?Malkiewicz  Kamilla?Klaczak  Krzysztof?Miga?a 《Theoretical and Applied Climatology》2015,119(3-4):419-432

The aim of this article is to present statistical forecasting models concerning the dynamics of Artemisia pollen seasons in Wroc?aw, including the start and end, the date of maximum pollen concentration and seasonal pollen index (SPI). For statistical evaluation, use was made of aerobiological and meteorological data from the last 10 years (2002–2011). Based on this data, agroclimatic indicators, i.e. crop heat units (CHUs), were determined for various averaging periods. The beginning of the Artemisia pollen season in the studied time period, on average, took place on 23 June. Its length usually varied between 26 and 45 days, and maximum daily concentrations occurred between 31 July and 18 August. It was found that the beginning of the pollen season depends, above all, on the values of CHUs and photothermal unit (PTU) (p?<?0.05) in the period from March to June, for various thermal thresholds. The date of maximum daily concentration correlates with sunshine duration, PTU and air temperature for June and July (p?<?0.05). On the other hand, SPI is connected with thermal variables, i.e. average, maximum and minimum air temperatures and CHUs and heliothermal unit (HTU) for July (p?<?0.05) and the beginning of spring. Based on the correlation analysis and the chosen variables, regression models for the beginning date of Artemisia pollen season and SPI were prepared, which were then verified by using leave-one-out cross-validation. A better fit between modelled and actual values was found for the analysis concerning the season start date than for the SPI.  相似文献   

Metadata Topic Harmonization and Semantic Search for Linked‐Data‐Driven Geoportals: A Case Study Using ArcGIS Online          下载免费PDF全文

Yingjie Hu  Krzysztof Janowicz  Sathya Prasad  Song Gao 《Transactions in GIS》2015,19(3):398-416

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Measurement of aerosol optical thickness over the Atlantic Ocean and in West Antarctica, 2006–2007     

Michał Posyniak  Krzysztof Markowicz 《Acta Geophysica》2009,57(2):494-508

In this paper, optical measurements of aerosol properties made during a ship cruise from Poland to Antarctic Station in September and October 2006, and during the cruise back to Gdynia in April and May 2007 are described. A large gradient of pollution between the clear South Atlantic and the dusty North Atlantic was observed. The maximum of aerosol optical thickness at a wavelength of 500 nm reached 0.4 at 20°N in September 2006 and 0.3 at 40°N in May 2007, respectively. Strong Saharan dust transport is suggested as an explanation for the small values of Ångström exponent observed (values of 0.2 and 0.4 on these respective dates). On the Southern Hemisphere the aerosol optical thickness at 500 nm ranged from 0.05 to 0.2. Significant increases of the aerosol optical thickness were associated with strong wind and sea salt production. Good agreement was found when the in situ measurements of aerosol optical thickness were compared to satellite retrievals and modelling results.  相似文献   

Do mowing regimes affect plant and soil biological activity in the mountain meadows of Southern Poland?     

Agnieszka Józefowska  Tomasz Zaleski  Jan Zarzycki  Krzysztof Frączek 《山地科学学报》2018,15(11):2409-2421

The soil biological activity of mountain meadows is a significant factor that determines the health and utility of these regions. The climax stage of this area is forest, but to maintain semi-natural grassland, which is characterised by high biodiversity,low-intensity land use(mowing or grazing) is necessarily required. To understand the effect of various mowing regimes on the soil biological activity and plants, the soil microbial activity(microbial biomass carbon, dehydrogenase activity and number of the cultivable fraction of soil microbial community),annelids community(density and species composition earthworms and enchytraeids) and plant species composition were investigated. The study area was located in the Pieniny National Park in the Carpathian Mountains, in a meadow belonging to the association Dactylis glomerata-Poa trivialis. The investigated variants were divided according to mowing regime:traditional scything – hand mowing(HM), mechanical mowing(MM), or the abandonment of mowing – nonmowing(NM). The microbial activities(expressed by,e.g. microbial biomass carbon and the number of phosphorus bacteria) were affected by the mowing regime. The density of earthworms was higher in the HM and MM than in the NM variants. The largest changes in plant species composition were caused by the abandonment of mowing(NM). The mean number of plant species was positively correlated with soil moisture, earthworm density, and microbial activity(expressed indirectly by dehydrogenases activity). The soil microbial community, such as vegetative bacteria forms and ammonifying bacteria,were positively associated with pH value, and the microbial and total organic carbon content. The results presented here indicate that there is no single form of optimal management for all living organisms.Decisions about mowing regimes, or abandonment of use, should be preceded by multi-aspect studies,including plants and soil biota.  相似文献   

Remnants of altered meteorite in the Cretaceous‐Paleogene clay boundary in Poland          下载免费PDF全文

Krzysztof Szopa  Tomasz Brachaniec  Łukasz Karwowski  Tomasz Krzykawski 《Meteoritics & planetary science》2017,52(4):612-622

Fossil iron meteorites are extremely rare in the geological sedimentary record. The paleometeorite described here is the first such finding at the Cretaceous‐Paleogene (K‐Pg) boundary. In the boundary clay from the outcrop at the Lechówka quarry (Poland), fragments of the paleometeorite were found in the bottom part of the host layer. The fragments of meteorite (2–6 mm in size) and meteoritic dust are metallic‐gray in color and have a total weight of 1.8181 g. Geochemical and petrographic analyses of the meteorite from Lechówka reveal the presence of Ni‐rich minerals with a total Ni amount of 2–3 wt%. The identified minerals are taenite, kamacite, schreibersite, Ni‐rich magnetite, and Ni‐rich goethite. No relicts of silicates or chromites were found. The investigated paleometeorite apparently represents an independent fall and does not seem to be derived from the K‐Pg impactor. The high degree of weathering did not permit the chemical classification of the meteorite fragments. However, the recognized mineral inventory, lack of silicates, and their pseudomorphs and texture may indicate that the meteorite remains were an iron meteorite.  相似文献   

<Emphasis Type="Italic">Pleurozium schreberi</Emphasis> of the Tatra mountains (Poland) used as a bioindicational system for observing long range atmospheric transport of chemical elements     

Krzysztof Kolon  Aleksandra Samecka-Cymerman  Alexander J. Kempers  Lucyna Mróz 《Journal of Atmospheric Chemistry》2010,66(3):157-166

Concentrations of the elements Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, V and Zn were measured in the moss Pleurozium schreberi from the Tatra National Park, one of the most protected regions in Poland. The moss samples were collected at different elevations between 860 and 2220 m a.s.l. P. schreberi was used as bioindicator for long range transported atmospheric pollution investigating the hypothesis that elevation influences the concentrations of elements in this moss. Principal component and classification analysis (PCCA) distinguished between mosses from the highest and the lowest elevations and mosses from West/East oriented valleys. P. schreberi from the highest elevations contained the highest concentrations of Cd, Cu, Cr, Fe, Mn, Pb, V and Zn. P. schreberi from the lowest elevation contained the highest concentration of K. P. schreberi from West/East oriented valleys contained the highest concentrations of Ni and Co. P. schreberi from the Tatra National Park, one of the most protected areas in Poland, receives metals originating from long distance aerial transport.  相似文献   

Use of mathematical modeling to investigate inter-aquifer contamination by organic-rich water through an unplugged well (central Wielkopolska, Poland)     

Krzysztof Dragon  Jozef Gorski  Marek Marciniak  Dariusz Kasztelan 《Hydrogeology Journal》2009,17(5):1257-1264

Hydrogeological research was performed to establish the origin of organic-rich water in a Quaternary aquifer (Wielkopolska Buried Valley aquifer, Poland). The spatial distribution of such water was determined by means of multilevel sampling with a packer. The nature, spatial distribution and chemistry of the organic-rich water suggest hydraulic connection between the Quaternary aquifer and the underlying Neogene aquifer. This connection may be enabled by an old abandoned, improperly plugged well, and must therefore be considered as an artificial hydraulic connection between hydrogeologically separated aquifers. For the verification of this hypothesis, a groundwater contaminant transport model was constructed. The results of contaminant transport modeling allow the contaminant transport parameters (transverse and longitudinal dispersivity) to be identified in the field. The numerical groundwater model was used for the prognosis of organic-rich water remediation, and for specification of water-resource management principles in the region where organic-rich water occurs. The results of this research enable the verification of assumptions regarding complex groundwater flow conditions in the boundary zone of a buried valley.  相似文献   

An Ontology‐Driven Framework and Web Portal for Spatial Decision Support1     

Naicong Li  Robert Raskin  Michael Goodchild  Krzysztof Janowicz 《Transactions in GIS》2012,16(3):313-329

Numerous systems and tools have been developed for spatial decision support (SDS), but they generally suffer from a lack of re‐usability, inconsistent terminology, and weak conceptualization. We introduce a collaborative effort by the SDS Consortium to build a SDS knowledge portal. We present the formal representation of knowledge about SDS, the various ontologies captured and made accessible by the portal, and the processes used to create them. We describe the portal in action, and the ways in which users can search, browse, and make use of its content. Finally, we discuss the lessons learned from this effort, and future development directions. Our work demonstrates how ontologies and semantic technologies can support the documentation and retrieval of dynamic knowledge in GIScience by offering flexible schemata instead of fixed data structures.  相似文献