A New 3‐D Solar Radiation Model for 3‐D City Models     

Jaroslav Hofierka  Marian Zlocha 《Transactions in GIS》2012,16(5):681-690

Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2‐D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3‐D approach. This study presents a new 3‐D solar radiation model for urban areas represented by 3‐D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3‐D vector data representing complex urban environments. The calculation procedure is based on the combined vector‐voxel approach segmenting the 3‐D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces.  相似文献   

Implications of bias evolution on measurements of the integrated Sachs–Wolfe effect: errors and biases in parameter estimation     

Bjoern Malte Schaefer  Marian Douspis  Nabila Aghanim 《Monthly notices of the Royal Astronomical Society》2009,397(2):925-932

The subject of this paper is a quantification of the impact of uncertainties in bias and bias evolution on the interpretation of measurements of the integrated Sachs–Wolfe (ISW) effect, in particular on the estimation of cosmological parameters. We carry out a Fisher matrix analysis for quantifying the degeneracies between the parameters of a dark energy cosmology and bias evolution, for the combination of the PLANCK microwave sky survey with the EUCLID main galaxy sample, where bias evolution   b ( a ) = b ₀+ (1 − a ) b_a   is modelled with two parameters b ₀ and   b_a   . Using a realistic bias model introduces a characteristic suppression of the ISW spectrum on large angular scales, due to the altered distance-weighting functions. The errors in estimating cosmological parameters if the data with evolving bias is interpreted in the framework of cosmologies with constant bias are quantified in an extended Fisher formalism. We find that the best-fitting values of all parameters are shifted by an amount comparable to the statistical accuracy: the estimation bias in units of the statistical accuracy amounts to 1.19 for Ω_m, 0.27 for σ₈ and 0.72 for w for bias evolution with   b_a = 1  . Leaving   b_a   open as a free parameter deteriorates the statistical accuracy, in particular on Ω_m and w .  相似文献   

Hill’s approximation in a restricted four-body problem     

Jaime Burgos-García  Marian Gidea 《Celestial Mechanics and Dynamical Astronomy》2015,122(2):117-141

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Crustal thickness in Vrancea area,Romania from S to P converted waves     

Marian Ivan 《Journal of Seismology》2011,15(2):317-328

Crustal thickness (CT) in Vrancea region (Romania) and adjacent area is investigated using 1294 S to P converted waves from the Moho discontinuity. A total of 269 local earthquakes in the depth range 99.8 to 171.1 km and recorded by 76 permanent and 46 temporary stations of the Romanian Seismological Network are used. Time difference between the converted wave and the direct P phase is corrected to a first order for epicentral distance and for the errors in focal depth, being finally inverted to CT. Greatest values for the Moho depth are observed for stations located in the Carpathians molasse foredeep and smaller values are observed in the Southern part of the Moesian Platform, for stations in the eastern part of Moldavian (East-European) Platform and in Dobrogea area, close to the Black Sea shoreline. In Vrancea epicentral area, an important CT variation is observed, from 42 km at MLR and 41.8 km at SIR, stations placed in the south-western part of the epicentral area, to 30.9 km at VRI, located above north-eastern part of the seismogenic volume. Stations CVO and OZU, placed in Transylvanian Basin in the proximity of the epicentral area, have CT values of 32.1 and 24.1 km, respectively. The results seem to support that a mantle delamination process is responsible for Vrancea intermediate depth seismicity.  相似文献   

Copper isotope fractionation by desert shrubs     

Jesica U. Navarrete  Marian Viveros  Joanne T. Ellzey  David M. Borrok 《Applied Geochemistry》2011

Copper has two naturally occurring stable isotopes of masses 63 and 65 which can undergo mass dependent fractionation during various biotic and abiotic chemical reactions. These interactions and their resulting Cu isotope fractionations can be used to determine the mechanisms involved in the cycling of Cu in natural systems. In this study, Cu isotope changes were investigated at the organismal level in the metal-accumulating desert plant, Prosopis pubescens. Initial results suggest that the lighter Cu isotope was preferentially incorporated into the leaves of the plant, which may suggest that Cu was actively transported via intracellular proteins. The roots and stems show a smaller degree of Cu isotope fractionation and the direction and magnitude of the fractionations was dependent upon the levels of Cu exposure. Based on this and previous work with bacteria and yeast, a trend is emerging that suggests the lighter Cu isotope is preferentially incorporated into biological components, while the heavier Cu isotope tends to become enriched in aqueous solutions. In bacteria, plants and animals, intracellular Cu concentrations are strictly regulated via dozens of enzymes that can bind, transport, and store Cu. Many of these enzymes reduce Cu(II) to Cu(I). These initial results seem to fit into a broader picture of Cu isotope cycling in natural systems where oxidation/reduction reactions are fundamental in controlling the distributions of Cu isotopes.  相似文献   

1–4 GHz type II-like radio bursts and pinch processes near the transition region     

Marian Karlický  Karel Jiřička 《Solar physics》1996,163(1):171-181

Analyzing 205 radio bursts observed by the Ondejov radiospectrograph in the 1–4 GHz frequency range during 1992 and 1993, we found 6 examples of type II-like radio bursts coinciding with impulsive phases of solar flares. These bursts were interpreted as radio manifestations of MHD (shock) waves generated during impulsive phases of flares in the vicinity of the transition region. Assuming a magnetic-field perturbation origin of these waves, we studied pinch processes in the current sheet near the transition region. In the 2-D MHD numerical model of this current sheet we demonstrated that 2-D pinch processes induced by radiative losses can trigger the impulsive phase of some flares and so generate the observed high-frequency type II-like radio bursts.  相似文献   

The effect of feldspar on quartz-H2O−CO2 dihedral angles at 4 kbar,with consequences for the behaviour of aqueous fluids in migmatites     

Marian B. Holness 《Contributions to Mineralogy and Petrology》1995,118(4):356-364

An investigation was made of the effect of trace amounts of feldspar (Na and/or K) on dihedral angles in the quartz-H₂O-CO₂ system at 4 kbar and 450–1050°C. Quartz-quartz-H₂O dihedral angles in feldspar-bearing quartz aggregates are observed to be the same as those in pure quartz aggregates at temperatures below 500°C. Above this temperature, they decrease with increasing temperature until the solidus. The final angle at the inception of melting is about 65° for microcline-quartz-H₂O and microcline-albite-quartz-H₂O, and much less than 60° (the critical value for formation of grain-edge fluid channels in an isotropic system) for the albite-quartz-H₂O system. CO₂ was observed to produce a constant quartz-quartz-fluid dihedral angle of 97° in feldspar-bearing quartz aggregates at all temperatures studied. Also examined were the dihedral angles for the two co-existing supersolidus fluids in quartz aggregates. In all systems the quartz-volatile fluid angle is greater than 60°, whereas the quartz-melt angle is lower than 60°. Both super-solidus angles decrease with increasing temperature. The transition from nonconnected to connected poro- sity with increasing temperature observed in the quartz-albite-H₂O system some tens of degrees below the solidus (termed a permeability transition), if a common feature of rocks near their melting points, will play an important role in controlling the permeability of high-grade rocks to aqueous fluids. Received: 27 October 1993 / Accepted: 11 July 1994  相似文献   

Bayesian Decision Analysis for Plume Interception Wells     

Hewa A. Wijedasa  Marian W. Kemblowski 《Ground water》1993,31(6):948-952

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Dynamic response of single-span beam bridges to a series of moving loads     

Marian Klasztorny  Jan Langer 《地震工程与结构动力学》1990,19(8):1107-1124

The paper makes a contribution to the problem of a stream of loads crossing a single-span beam bridge. There are considered the basic load models, in the form of a stream of fixed amplitude forces, unsprung masses and viscoelastic oscillators. The matrix equations of motion of the system are formulated and discussed. The problem of dynamic stability and steady-state response of a bridge carrying a periodic stream of inertial loads is formulated and solved. The paper also includes a vibration study of a beam bridge subjected to a uniform stream of moving loads, of a limited or unlimited number of load cycles.  相似文献   

Foliar Applied Nickel on Buckwheat (Fagopyrum esculentum) Induced Phenolic Compounds as Potential Antioxidants     

Oksana Sytar  Marian Brestic  Abhay Kumar  M. N. V. Prasad  Nataliya Taran  Iryna Smetanska 《洁净——土壤、空气、水》2013,41(11):1129-1137

In this study, Fagopyrum esculentum (common buckwheat) sprayed with nickel (Ni) (0, 0.5, 1.0, 3.0, and 5.0 mM) for different duration has been investigated for Ni accumulation, malondialdehyde (MDA), total phenolics, and phenolic acids. Ni accumulation significantly increased in dose‐dependent manner. Plants exposed for 72 h, showed visible damages as chlorosis and irreversible necrosis. The MDA and total phenolic contents increased at 24 h of Ni treatments. HPLC data revealed that phenolic acids are in good correlation with concentration and durations of treatments. After 24 and 48 h the contents of chlorogenic, p‐hydroxybenzoic, hesperetic, p‐anisic, and caffeic acids increased in Ni treated leaves. On the other hand, p‐hydroxybenzoic, hesperetic, p‐anisic, p‐coumaric, caffeic acids contents decreased after 72 h of Ni exposure. Vanillic and cinnamic acid followed same pattern and increased significantly at 3.0 and 5.0 mM after 48 h of Ni exposure. It may suggest that buckwheat can be possible hyperaccumulators of Ni, because of high Ni accumulation in tissues through foliar treatment. Furthermore, the analyzed phenolic acids have potential role as antioxidants, which provide tolerance to buckwheat against Ni treatment.  相似文献