Heterogeneity in hedonic modelling of house prices: looking at buyers’ household profiles   总被引：2，自引：0，他引：2  

Yan Kestens  Marius Thériault  François Des Rosiers 《Journal of Geographical Systems》2006,8(1):61-96

This paper introduces household-level data into hedonic models in order to measure the heterogeneity of implicit prices regarding household type, age, educational attainment, income, and the previous tenure status of the buyers. Two methods are used for this purpose: a first series of models uses expansion terms, whereas a second series applies Geographically Weighted Regressions. Both methods yield conclusive results, showing that the marginal value given to certain property specifics and location attributes do vary regarding the characteristics of the buyer’s household. Particularly, major findings concern the significant effect of income on the location rent as well as the premium paid by highly-educated households in order to fulfil social homogeneity.  相似文献   

Electrons in the solar corona     

Dollfus  Audouin  Laffineur  Marius  Mouradian  Zadig 《Solar physics》1974,38(2):367-376

We discuss a model for the formation of the chromospheric Ca ii K line which does not make the usual assumption of complete redistribution. Using a physically reasonable scattering model, we find significant departures due to the frequency dependence of the line source function, particularly in the relative intensity and centre-to-limb behaviour of the K₁ parts of the line and in the asymmetry produced by differential velocity fields. We conclude that the frequency dependence of the K line source function must be considered in quantitative models for the formation of the K line.  相似文献   

Spatio‐Temporal Object‐Oriented Data Model for Disaggregate Travel Behavior     

Ali Frihida  Danielle J. Marceau  Marius Thriault 《Transactions in GIS》2002,6(3):277-294

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A simple gibbsite analyzer for rapid field determination of the available alumina content in bauxites     

Marius J. van Essen  Johannes A. C. Heynen  Adriaan H. van der Veen  Gerrit H. Vonkeman 《Mineralium Deposita》1971,6(1):41-48

A portable gibbsite analyzer suited for field operation and intended for rapid determination of available alumina is described. The available alumina content is calculated from the relative weight loss caused by the dehydration of gibbsite. More than 100 samples of gibbsite-containing bauxites of different origin, were analyzed with this apparatus. The results always appeared to be correct within 10% of the actual content. In the laboratory, an accuracy of ±2.60% gibbsite, and a reproducibility of ±1.87% gibbsite, both at the 95% confidence interval, could be achieved. The apparatus can be used under tropical conditions. Its weight is 13 kg. It can be fed from a motor-driven generator weighing 18 kg. The duration of a single analysis in the field is 30–40 minutes. In the laboratory about 25 analyses can be performed within 8 hours. The apparatus can be handled by an untrained operator. One operator can run at least two analyzers at a time. The complete set-up, including the generator, costs less than US $ 1500.

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Zusammenfassung Ein tragbarer Apparat für die Gibbsit Bestimmung im Freien wird beschrieben. Der Gibbsitgehalt wird berechnet aus dem Gewichtsverlust während der Entwässerung. Für Gibbsit-haltige Bauxite, die mit diesem Apparat analysiert sind, wurden Resultate gefunden, die immer weniger als 10% vom richtigen Gehalt abwichen. Im Labor konnte eine Genauigkeit von ±2.60% Gibbsit und eine Reproduzierbarkeit von ±1.87% Gibbsit, beide mit einer Wahrscheinlichkeit von 95%, erreicht werden. Der Apparat ist ausgerüstet für den Gebrauch in den Tropen. Er wiegt 13 kg und kann von einem durch einen Benzinmotor angetriebenen Generator gespeist werden. Der Generator hat ein Gewicht von 18 kg. Eine einzige Bestimmung im Freien dauert 30–40 Minuten. Im Labor können etwa 25 Bestimmungen innerhalb von 8 Stunden gemacht werden. Ein Mann kann mindestens zwei Apparate zugleich beobachten. Apparat und Generator kosteten weniger als US $ 1500.

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Retrieval of effective cloud field parameters from radiometric data     

Paulescu  Marius  Badescu  Viorel  Brabec  Marek 《Theoretical and Applied Climatology》2018,132(1-2):437-450

Theoretical and Applied Climatology - This study presents evaluation of the ability of Rossby Centre Regional Climate Model (RCA4) driven by nine global circulation models (GCMs), to skilfully...  相似文献   

What Ångström—Prescott equation tells us about the cloud and clear-sky climatologies?     

Paulescu  Marius  Badescu  Viorel  Budea  Sanda  Dumitrescu  Alexandru 《Theoretical and Applied Climatology》2022,147(1-2):239-250

Theoretical and Applied Climatology - The Ångström–Prescott equation defines generically the relationship between solar energy available at ground level and sunshine duration. From...  相似文献   

Winter air pollution episodes over Cape Town     

Mark Jury  Annegret Tegen  Eric Ngeleza  Marius Dutoit 《Boundary-Layer Meteorology》1990,53(1-2):1-20

Episodes of air pollution over Cape Town are identified using multi-year time series of SO₂ and NO_x concentrations. The associated meteorological conditions are studied both from synoptic and meso-scale perspectives using detailed observations, statistical analyses and numerical model simulations. Atmospheric conditions are most conducive to poor dispersion in the winter months, April to August. Episodes are initiated by the eastward passage of an intense, synoptic anticyclone over the Cape Town area. The 850 hPa geopotential height typically rises to 1600 gpm a day before the episode. Northeasterly berg winds are common and act to dry out the boundary layer. A nocturnal radiation inversion forms with a mean strength of 11 °C and extends from the surface to 953 hPa (500m). Gradient and thermal winds tend to cancel out providing for low net transport rates for near-surface emissions. Acoustic sounder profiles for two episodes illustrate a reduction of winds and turbulence within the boundary layer. The episode surface circulation is simulated using a two-layer model. Hills which lie upstream of Cape Town obstruct the northeasterly flow during the morning.  相似文献   

Fluid mud dynamics in the Weser estuary turbidity zone tracked by high-resolution side-scan sonar and parametric sub-bottom profiler   总被引：1，自引：0，他引：1  

Kerstin Schrottke  Marius Becker  Alexander Bartholomä  Burghard W. Flemming  Dierk Hebbeln 《Geo-Marine Letters》2006,26(3):185-198

Fluid mud in estuarine turbidity maximum zones (TMZ) can pose considerable navigation risks due to potentially substantial reductions in nautical depth, coupled with an inherent difficulty of detection by conventional echo-sounders. Despite intensive research efforts, however, our knowledge about the spatial and temporal dynamics of fluid mud is still not sufficient. In this study, the combined use of a side-scan sonar (Sportscan®, Imagenex) and a parametric sub-bottom profiler (SES-2000®, Innomar Technology GmbH) has proved successful for high-resolution fluid mud detection and volumetric quantification in an estuarine environment. In 2004 and 2005, repeated surveys were conducted in the navigation channel of the upper meso- to lower macrotidal Weser estuary TMZ (German North Sea coast) at different tidal stages and river discharges. Current velocity data were simultaneously collected by 1,200-kHz broadband ADCP (RDInstruments) measurements. Ground-truthing was carried out by means of grab sampling and gravity coring, adapted to fluid mud conditions. It was found that fluid mud occurrence in the Weser estuary is highly variable on time scales of a few hours and spatial scales of several metres. The riverbed is characterised by sand and mud deposits, and a complex morphology including subaqueous dunes and smooth bed deposits intermittently overlain by fluid mud. Thus, a continuous, coherent fluid mud body covering the entire TMZ riverbed was not observed. Rather, spatial distribution was patchy and highly dependent on suspended particulate matter (SPM) concentrations in the water column, as a result of which local fluid mud deposits varied in thickness from centimetres to metres. The formation of fluid mud was largely restricted to slack water, although slack-water conditions were not necessarily associated with large-scale fluid mud appearance. Advective SPM transport of resuspended fluid mud seems to be the most plausible explanation for the high spatial variability observed, even between two successive tides. The amount of fluid mud deposited and resuspended in the course of a tidal cycle can reach several 10s of tons even in small riverbed depressions.  相似文献   

Cadmium-binding proteins in the blue crab, callinectes sapidus: laboratory-field comparison     

David W. Engel  Marius Brouwer 《Marine environmental research》1984,14(1-4)

The blue crab, Callinectes sapidus, is distributed along the east coast of the United States from Cape Cod, Mass., through the Gulf of Mexico, including both relatively unpolluted coastal areas and estuaries contaminated with trace metals. Cadmium is of particular concern because it is concentrated in the digestive glands of blue crabs and can be passed on to consumer organisms. Tissue concentrations and partitioning of trace metals from crabs exposed in the laboratory to 10 ppb dissolved cadmium for 40 days were compared with blue crabs collected from two locations on the Hudson River, NY, Foundry Cove and Haverstraw Bay, Foundry Cove and Haverstraw Bay, both of which have elevated trace metal levels relative to estuarine areas near Beaufort, NC. Crab digestive glands, gills and muscle were removed and analyzed for total cadmium, copper, zinc and nickel concentrations using acid digestion and atomic absorption spectrophotometry, and metal-binding (metallothionein-like) proteins were determined by gel-filtration chromatography. In crabs exposed to cadmium in the laboratory, the cytosolic partitioning was similar to previous investigations at our laboratory where higher levels of cadmium (100 ppb) and shorter exposure times (14 days) were used. The similarity in cadmium partitioning from these two separate experiments indicates dose independence. In crabs from polluted environments the digestive glands contained the highest concentrations of trace metals. Chromatograms of the cytosol from the digestive glands and gills from both field and laboratory exposed crabs showed similar distributions of cadmium, copper and zinc. The gills of both field and laboratory-exposed crabs had metal-binding proteins that contained mostly cadmium, and the digestive glands had metallothionein-like proteins that contained cadmium, copper and zinc. Estimated molecular weights for these proteins were similar to the metallothioneins found in other crustaceans and mammals.  相似文献   

Resolving frontal structures: on the payoff using a less diffusive but computationally more expensive advection scheme     

Knut Barthel  Ute Daewel  Dhanya Pushpadas  Corinna Schrum  Marius ?rthun  Henning Wehde 《Ocean Dynamics》2012,62(10-12):1457-1470

This article presents some advantages using a shape-preserving total variation diminishing (TVD) advection scheme in an ecosystem model. The superbee flux-limiter has been used to the second-order Lax–Wendroff advection scheme to make it TVD. We performed simulations for three shelf sea regions with different characteristic time scales, namely, the North Sea, the Barents Sea, and the Baltic Sea. To explore the advantages, we also performed reference runs with the much simpler and computationally cheaper upwind advection scheme. Frontal structures are much better resolved with the TVD scheme. The bottom salinity in the Baltic Sea stays at realistic values throughout the 10-year simulation with the TVD scheme, while with the upwind scheme, it drifts towards lower values and the permanent haline stratification in the Baltic is almost completely eroded within one seasonal cycle. Only when applying TVD for both the vertical and horizontal advections the model succeeded to preserve haline stratification in the decadal simulation. Lower trophic level patterns are far better reproduced with the TVD scheme, and for the estimated cod larval survival, the advantages seem to be even stronger. Simulations using the TVD-derived prey fields identified distinct regions such as Dogger Bank to favor potential larvae survival (PLS), which did not appear as particularly favorable in the upstream simulations. The TVD scheme needs about 25?% more time on the central processing unit (CPU) in case of a pure hydrodynamic setup with only two scalar state variables (Barents Sea application). The additional CPU time cost increases for a coupled physical–biological model application with a large number of state variables. However, this is more than compensated by all the advantages found, and, hence, we conclude that it is worthwhile to use the TVD scheme in our ecosystem model.  相似文献