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Author |
Gielis, J.; Caratelli, D.; Fougerolle, Y.; Ricci, P.E.; Tavkelidze, I.; Gerats, T. |
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Title |
Universal natural shapes : from unifying shape description to simple methods for shape analysis and boundary value problems |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
PLoS ONE |
Abbreviated Journal |
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Volume |
7 |
Issue |
9 |
Pages |
e29324-11 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Gielis curves and surfaces can describe a wide range of natural shapes and they have been used in various studies in biology and physics as descriptive tool. This has stimulated the generalization of widely used computational methods. Here we show that proper normalization of the Levenberg-Marquardt algorithm allows for efficient and robust reconstruction of Gielis curves, including self-intersecting and asymmetric curves, without increasing the overall complexity of the algorithm. Then, we show how complex curves of k-type can be constructed and how solutions to the Dirichlet problem for the Laplace equation on these complex domains can be derived using a semi-Fourier method. In all three methods, descriptive and computational power and efficiency is obtained in a surprisingly simple way. |
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Wos |
000309517500001 |
Publication Date |
2012-09-30 |
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ISSN |
1932-6203 |
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UA library record; WoS full record; WoS citing articles |
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Call Number  |
UA @ admin @ c:irua:102202 |
Serial |
8711 |
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Author |
Haest, P.J.; Springael, D.; Seuntjens, P.; Smolders, E. |
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Title |
Self-inhibition can limit biologically enhanced TCE dissolution from a TCE DNAPL |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Chemosphere |
Abbreviated Journal |
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Volume |
89 |
Issue |
11 |
Pages |
1369-1375 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Biodegradation of trichloroethene (TCE) near a Dense Non Aqueous Phase Liquid (DNAPL) can enhance the dissolution rate of the DNAPL by increasing the concentration gradient at the DNAPL-water interface. Two-dimensional flow-through sand boxes containing a ICE DNAPL and inoculated with a TCE dechlorinating consortium were set up to measure this bio-enhanced dissolution under anaerobic conditions. The total mass of TCE and daughter products in the effluent of the biotic boxes was 3-6 fold larger than in the effluent of the abiotic box. However, the mass of daughter products only accounted for 19-55% of the total mass of chlorinated compounds in the effluent, suggesting that bio-enhanced dissolution factors were maximally 1.3-2.2. The enhanced dissolution most likely primarily resulted from variable DNAPL distribution rather than biodegradation. Specific dechlorination rates previously determined in a stirred liquid medium were used in a reactive transport model to identify the rate limiting factors. The model adequately simulated the overall TCE degradation when predicted resident microbial numbers approached observed values and indicated an enhancement factor for TCE dissolution of 1.01. The model shows that dechlorination of TCE in the 20 box was limited due to the short residence time and the self-inhibition of the TCE degradation. A parameter sensitivity analysis predicts that the bio-enhanced dissolution factor for this TCE source zone can only exceed a value of 2 if the TCE self-inhibition is drastically reduced (when a TCE tolerant dehalogenating community is present) or if the DNAPL is located in a low-permeable layer with a small Darcy velocity. (C) 2012 Elsevier Ltd. All rights reserved. |
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Wos |
000310112600015 |
Publication Date |
2012-06-30 |
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ISSN |
0045-6535; 1879-1298 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:102142 |
Serial |
8512 |
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Author |
Potgieter-Vermaak, S.; Rotondo, G.; Novacovic, V.; Rollins, S.; Van Grieken, R. |
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Title |
Component-specific toxic concerns of the inhalable fraction of urban road dust |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Environmental geochemistry and health |
Abbreviated Journal |
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Volume |
34 |
Issue |
6 |
Pages |
689-696 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Continuous global urbanisation causes an ever-growing ecological footprint of pollution. Road dust (RD), one of these pollutants, poses a health concern due to carcinogenic and toxic components potentially present in the micron-sized fractions. The literature reports on the concentrations of trace, toxic metals and metalloids present in RD (Hooker and Nathanail in Chem Geol 226:340-351, 2006), but the literature on its molecular composition is limited. Recent reports on the bioaccessibility of platinum group metals are also reported (Colombo et al. in Chem Geol 226:340-351, 2008). In vitro and animal toxicological studies confirmed that the chemical composition of inhaled particles plays a major role in its toxic, genotoxic and carcinogenic mechanisms, but the component-specific toxic effects are still not understood. Particle-bound airborne transition metals can also lead to the production of reactive oxygen species in lung tissue; a special concern amongst particularly susceptible cohorts (children and elderly). The characterisation of the molecular composition of the fine fraction is evidently of importance for public health. During a pilot study, partially characterised size-fractioned RD samples (Barrett et al. in Eviron Sci Technol 44:2940-2946, 2010) were analysed for their elemental concentration using X-ray fluorescence spectrometry and inductively coupled plasma mass spectrometry. In addition, separately dispersed particles (200 particles per size fraction) were analysed individually by means of computer-controlled electron probe X-ray micro-analysis (CC-EPXMA) and their molecular structure probed by studying elemental associations. These were correlated with micro-Raman spectroscopy (MRS) results. It was found that the fine fraction (< 38 mu m) had the highest Pb (238 ppm) and Cr (171 ppm) concentrations. The CC-EPXMA data showed > 50 % association of Cr-rich particles with Pb, and the MRS data showed that the Cr was mostly present as lead chromate and therefore in the Cr(VI) oxidation state. Concentrations of both Pb and Cr decreased substantially (279 (< 38 mu m)-13 ppm (< 1 mm); 171 (< 38 mu m)-91 ppm (< 1 mm), respectively) in the larger fractions. Apart from rather alarmingly high concentrations of oxidative stressors (Cu, Fe, Mn), the carcinogenic and toxic potential of the inhalable fraction is evident. Preliminary bioaccessibility data indicated that both Cr and Pb are readily mobilised in artificial lysosomal liquid and up to 19 % of Cr and 47 % of Pb were released. |
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Wos |
000310540300005 |
Publication Date |
2012-09-28 |
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ISSN |
0269-4042 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:102135 |
Serial |
7699 |
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Author |
Vos, P.E.J.; Nikolova, I.; Janssen, S. |
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Title |
A high-order model for accurately simulating the size distribution of ultrafine particles in a traffic tunnel |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Atmospheric environment : an international journal |
Abbreviated Journal |
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Volume |
59 |
Issue |
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Pages |
415-425 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
We present a computational model for simulating the dispersion of traffic emitted particulate matter inside a road tunnel, with an emphasis on the number concentration of ultrafine particles (UFP). The model primarily calculates the size distribution of the particle number concentration at each location inside the tunnel. The proposed model differs from existing models in the sense that it uses a continuous representation of the size distribution based upon the high-order finite element method and that it solves the governing equations using the state-of-the-art discontinuous Galerkin method. Next to the traditional transport processes, the model also implements the most important aerosol transformation processes such as coagulation, condensation and dry deposition. It is shown that based upon parametrisations found in literature, the process of condensation in a traffic tunnel cannot properly be modelled. Therefore, we present a correction factor that allows for a better parametrisation. The adequate performance of the model is demonstrated by both a verification study and a validation study. For the verification we show that the discretisation error converges consistently while for the validation we compare the modelled results with a suitable set of data from a UFP measurement campaign in a Taiwanese traffic tunnel. The model is shown to correctly simulate the observed behaviour and by applying a statistical model evaluation we demonstrate that the proposed model meets widely accepted air quality model acceptance criteria. (C) 2012 Elsevier Ltd. All rights reserved. |
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Wos |
000309081100047 |
Publication Date |
2012-05-25 |
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ISSN |
1352-2310 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:101793 |
Serial |
8033 |
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Author |
Fenu, A.; De Wilde, W.; Gaertner, M.; Weemaes, M.; de Gueldre, G.; van de Steene, B. |
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Title |
Elaborating the membrane life concept in a full scale hollow-fibers MBR |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Journal of membrane science |
Abbreviated Journal |
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Volume |
421 |
Issue |
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Pages |
349-354 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
The membrane life-time has a strong impact on competitivity and viability of MBRs. This study critically analyzes the membrane life-time concept, approaching it through different assessment methods. A full scale MBR's membrane life-time was assessed on the following: (i) maintaining the permeate flow throughput to the MBR; (ii) the permeability decline; (iii) oxidative aging; (iv) the increase in energy costs; and (v) mechanical aging. The method based on permeability decline provides a membrane life-time estimate up to a theoretical end. It was further elaborated inherently to operations with no long-term flux decline. The increase in operating pressure remains the main end-of-life trigger for deciding when to replace membrane modules. On the contrary, mechanical and permeate flow throughput analysis of the data are not able to provide a clear estimate of the membrane life-time. As for the membrane life-time estimation based on chlorine contact, it was found to be too optimistic. Complete irreversible fouling occurs before maximum contact time with chlorine is reached. At end-of-life operating conditions, the energy consumption raised of 170% due to the reduced flow rate. The cost raise appears high but still affordable. Earlier membrane replacement thus can never be counterbalanced by energy costs saving. (C) 2012 Elsevier B.V. All rights reserved. |
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Wos |
000308741100039 |
Publication Date |
2012-08-07 |
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ISSN |
0376-7388 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:101790 |
Serial |
7856 |
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Author |
Mishra, V.K.; Kumar, P.; Van Poppel, M.; Bleux, N.; Frijns, E.; Reggente, M.; Berghmans, P.; Int Panis, L.; Samson, R. |
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Title |
Wintertime spatio-temporal variation of ultrafine particles in a Belgian city |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
The science of the total environment |
Abbreviated Journal |
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Volume |
431 |
Issue |
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Pages |
307-313 |
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Keywords |
A1 Journal article; Sustainable Energy, Air and Water Technology (DuEL) |
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Abstract |
Simultaneous measurements of ultrafine particles (UFPs) were carried out at four sampling locations situated within a 1 km(2) grid area in a Belgian city, Borgerhout (Antwerp). All sampling sites had different orientation and height of buildings and dissimilar levels of anthropogenic activities (mainly traffic volume). The aims were to investigate: (i) the spatio-temporal variation of UFP within the area, (ii) the effect of wind direction with respect to the volume of traffic on UFP levels, and (iii) the spatial representativeness of the official monitoring station situated in the study area. All sampling sites followed similar diurnal patterns of UFP variation, but effects of local traffic emissions were evident. Wind direction also had a profound influence on UFP concentrations at certain sites. The results indicated a clear influence of local weather conditions and the more dominant effect of traffic volumes. Our analysis indicated that the regional air quality monitoring station represented the other sampling sites in the study area reasonably well; temporal patterns were found to be comparable though the absolute average concentrations showed differences of up to 35%. (C) 2012 Elsevier B.V. All rights reserved. |
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Wos |
000306887900037 |
Publication Date |
2012-06-14 |
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ISSN |
0048-9697; 1879-1026 |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:101123 |
Serial |
8759 |
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Author |
van der Snickt, G. |
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Title |
James Ensor's pigments studied by means of portable and synchrotron radiation-based X-ray techniques : evolution, context and degradation |
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Doctoral thesis |
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Year |
2012 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
501 p. |
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Keywords |
Doctoral thesis; Art; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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no |
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Call Number |
UA @ admin @ c:irua:100628 |
Serial |
8135 |
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Author |
Horemans, B.; Schalm, O.; De Wael, K.; Cardell, C.; Van Grieken, R. |
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Title |
Atmospheric composition and micro-climate in the Alhambra monument, Granada (Spain), in the context of preventive conservation |
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P1 Proceeding |
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Year |
2012 |
Publication |
IOP conference series : materials science and engineering |
Abbreviated Journal |
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Volume |
37 |
Issue |
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Pages |
012002-12008 |
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Keywords |
P1 Proceeding; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
The world famous Alhambra monument in Granada, Southern Spain, listed as UNESCO world cultural heritage since 1984, represents probably the most beautiful example of Islamic art and architecture from the Middle Ages in Europe. It is visited by ca. 2 million people annually. Granada is situated in a natural basin, surrounded by mountains with altitudes up to 3500 m. Due to this topography and the prevailing low wind speeds, pollution-derived and especially traffic-derived particulate matter often accumulates in the urban air. In order to evaluate the potential conservation risks from the surrounding air, the atmospheric composition in the Alhambra monument was evaluated. Indoor temperature and relative humidity fluctuations were evaluated for their potential degenerative effects. Furthermore, the atmospheric composition in the Alhambra was analyzed in terms of inorganic gases (NO2, SO2, O3, and NH3) and black carbon. It was found that the open architecture protected the indoor environments from developing a potentially harmful microclimate, such as the build-up of humidity resulting from the huge number of daily tourists. On the downside, the strong ventilation made the indoor air hardly different from outdoor air, as characterized by strong diurnal temperature and relative humidity gradients and high traffic-derived pollutant levels. |
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000307662000002 |
Publication Date |
2012-07-16 |
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ISSN |
1757-8981; 1757-899x |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Times cited |
1 |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:100112 |
Serial |
5484 |
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Author |
Rojas, C.M.; Van Grieken, R.E.; Laane, R.W. |
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Title |
Comparison of 3 dry deposition models applied to field-measurements in the Southern Bight of the North-Sea |
Type |
A1 Journal article |
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Year |
1993 |
Publication |
Atmospheric environment |
Abbreviated Journal |
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Volume |
27 |
Issue |
3 |
Pages |
363-370 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation) |
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Abstract |
Dry deposition velocities have been calculated using three different approaches. Turbulent wind profile theory has been used to predict the drag coefficient, wind speed and friction velocity at 10 m height when the wind speed is measured at a higher altitude. The resulting parameters were introduced in a two-layer deposition model. The second approach was the well-known model of Slinn and Slinn (1980, Atmospheric Environment 14, 1013-1016), whereas the third corresponded to the model published by Williams (1982, Atmospheric Environment 16, 1933 1938). Results point to clear differences. However, in a field experiment carried out at the Southern Bight of the North Sea, all three approaches show relatively comparable results. The role played by the size distribution of atmospheric particulate matter is essential. In our case any of the three models could have given satisfactory outcomes taking into account the wide spread of the experimental results cited in the literature for the same airshed. |
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Wos |
A1993KQ75200008 |
Publication Date |
2003-08-06 |
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ISSN |
0004-6981 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:100018 |
Serial |
7690 |
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