scholarly journals Vertical Tracer Concentration Profiles Measured during the Joint Urban 2003 Dispersion Study

2007 ◽  
Vol 46 (12) ◽  
pp. 2019-2037 ◽  
Author(s):  
Julia E. Flaherty ◽  
Brian Lamb ◽  
K. Jerry Allwine ◽  
Eugene Allwine
Keyword(s):  
Urban Landscape ◽  
Ground Level ◽  
Concentration Profiles ◽  
Tracer Gas ◽  
Tracer Concentration ◽  
Measured Concentration ◽  
Tracer Dispersion ◽  
Open Country ◽  
Using Data ◽  
Atmospheric Tracer

Abstract An atmospheric tracer dispersion study known as Joint Urban 2003 was conducted in Oklahoma City, Oklahoma, during July of 2003. As part of this field program, vertical concentration profiles were measured at approximately 1 km from the downtown ground-level tracer gas release locations. These profiles showed that the urban landscape was very effective in mixing the plume vertically. In general, the lowest concentration measured along the profile was within 50% of the highest concentration in any given 5-min measurement period. The general slope of the concentration profiles was bounded by a Gaussian distribution with Briggs’s urban equations (stability classes D and E/F) for vertical dispersion. However, measured concentration maxima occurred at levels above the surface, which would not be predicted by Gaussian formulations. Variations in tracer concentration observed in the time series between different release periods were related to changes in wind direction as opposed to changes in turbulence. This was demonstrated using data from mobile analyzers that captured the width of the plume by traveling east to west along nearby streets. These mobile-van-analyzer data were also used to compute plume widths. Plume widths increased for wind directions at larger angles to the street grid, and a simple model comprising adjusted open-country dispersion coefficients and a street channeling component, were used to describe the measured widths. This dispersion dataset is a valuable asset not only for developing advanced tools for emergency-response situations in the event of a toxic release but also for refining air-quality models.

Non-axisymmetric turbulent mass transfer in a circular tube

1969 ◽  
Vol 38 (3) ◽  
pp. 457-472 ◽  
Author(s):  
Alan Quarmby ◽  
R. K. Anand
Keyword(s):  
Mass Transfer ◽  
Circular Tube ◽  
Eddy Diffusivity ◽  
Concentration Profiles ◽  
Tracer Gas ◽  
Direct Evaluation ◽  
Measured Concentration ◽  
Eddy Diffusivities ◽  
Fluid Properties ◽  
Fully Developed Turbulent Flow

Theory and experiment are presented for mass transfer into a fully developed turbulent flow in a plain circular tube in two non-axisymmetric cases. The cases studied are a diametral line source and a discontinuous ring source, in which there is a uniform mass flux over rectangular areas of the tube wall. A comparison is made between the concentration profiles predicted by the solutions of the diffusion equation and experiments using nitrous oxide, Schmidt number S = 0·77, as a tracer gas in air. The range of experiments covers Reynolds numbers R from 20,000 to 120,000.In the analysis, the assumption is made that the tangential and radial eddy diffusivities of mass are equal at a point. The radial diffusivity of mass, which is a function of radial position, is related to the radial eddy diffusivity of momentum by a ratio, which takes account of fluid properties and the value of the radial eddy diffusivity of momentum. The satisfactory agreement between analysis and experiment establishes the correctness of this assumption. Further confirmation was obtained by direct evaluation of the tangential eddy diffusivity of mass from the measured concentration profiles.

Validation of CALPUFF Applicability within Urban Area

2013 ◽  
Vol 726-731 ◽  
pp. 1813-1816
Author(s):  
Long Xiang Dong ◽  
Hong Chao Zuo ◽  
Wen Cheng Dong
Keyword(s):  
Urban Area ◽  
Single Point ◽  
Urban Canopy ◽  
Tracer Experiment ◽  
Gansu Province ◽  
Canopy Layer ◽  
Tracer Concentration ◽  
Tracer Dispersion ◽  
Simulation Error ◽  
Atmospheric Tracer

An atmospheric tracer dispersion study known as Urban Meteorological and Tracer Experiment was carried out in Yuzhong County, Gansu province in northwest of China, during October of 2011. By using the observational data, the applicability of CALPUFF model based on Gaussian formula was verified within urban area. The results show that (i) CALPUFF model can reasonably reflect the actual observations on the whole, and the high value centers of tracer concentration was changed with wind direction over the urban canopy layer. (ii) The simulated plume central axis has a bias of 10-15° with observations, and the simulation error is very much big at the single point, especially at the ground.

Diffusion and Migration of Ions in Sedimentary Rock Matrix: Effects of Ionic Strength and Tracer Concentration on Diffusion of Cs+ ions in Sandstone

2003 ◽  
Vol 807 ◽  
Author(s):  
Haruo Sato
Keyword(s):  
Ionic Strength ◽  
Matrix Effects ◽  
Chemical Properties ◽  
Effective Diffusivity ◽  
Concentration Profiles ◽  
Tracer Concentration ◽  
And Migration ◽  
Physical And Chemical ◽  
Cs Ions ◽  
And Chemical Properties

ABSTRACTIn-diffusion experiments for Cs+ and I− in sandstone were performed as a function of ionic strength ([NaCl]=0.01, 0.51M) and tracer concentration ([CsI]=7.5E-5, 1.5E-2M) together with the measurements of the physical and chemical properties of sandstone, and apparent diffusivities (Da) for Cs+ were obtained. The obtained Da-values for Cs+ scarcely depended on [NaCl], but increased with increasing [Cs+]. This trend is consistent with that of rock capacity factors (α), indicating that distribution coefficient (Kd) onto sandstone and effective diffusivity scarcely depend on [NaCl]. The concentration profiles of I− were all in already breakthrough. Although this indicates that I− diffusion is faster than that of Cs+, the concentration profiles of I− may have been lower than those for blank samples, judging synthetically from the correlations between α-values and the concentration profiles of Cs+ and from the concentration profiles of I− in the blank samples. Finally, the effects of [Cs+] and[NaCl] on Kd/-values for Cs+ were discussed from the viewpoint of adsorption by ion exchange and electrostatic attraction. The kd-values were considered to be combined sorption by both reactions.

Validation of a Two-Pool Model for the Kinetics of ß2-Microglobulin

2002 ◽  
Vol 25 (5) ◽  
pp. 411-420 ◽  
Author(s):  
S. Stiller ◽  
X.Q. Xu ◽  
N. Gruner ◽  
J. Vienken ◽  
H. Mann
Keyword(s):  
Standard Deviation ◽  
Plasma Concentrations ◽  
Generation Rate ◽  
Secondary Amyloidosis ◽  
Concentration Profiles ◽  
Dialysis Dose ◽  
Measured Concentration ◽  
Pool Model ◽  
Efficacy Parameters ◽  
Beta 2 Microglobulin

Secondary amyloidosis due to beta-2-microglobulin (ß2-m) is a serious long-term complication in patients on regular dialysis therapy. ß2-m can be considered a middle-molecule marker used to facilitate the assessment of dialysis efficacy. For this purpose, a validated model that calculates characteristic efficacy parameters, such as Kt/V, TAC and generation rate, is needed. There is general agreement that ß2-m-kinetics should be described by a two-pool model, but little has been published to validate such an approach. We measured the ß2-m concentration profiles of eight stable patients during hemodialysis (HD) at the start of treatment, after 30 minutes, after 60 minutes, and every hour until the end. Thereafter they were measured at 10-minute intervals for an hour. The dialyser clearances were determined from the plasma concentrations in front of and behind the dialyser twice during each session – after 1 hour, and 4 hours from the start of treatment. The kinetic parameters of a two-pool model (e.g. the compartment volumes V1 and V2, the mass transfer coefficient K12 and the generation rate G) were determined from the optimal fit of the measured concentration profile. The table below summarises the results by giving the mean and standard deviation for each parameter: V (liters) V1/V2 V % TBW K12 m(ml/min) G (mg/kg/day) 10.0 ± 1.6 4.60 ± 1.8 28.4 ± 3.1 56.3 ± 25.2 2.50 ± 0.66 Inter-individual differences in V1/V2 and K12 were high, ranging from 2.5 to 10.0 for V1/V2 and from 26 to 140 for K12. Error analysis suggested that these wide ranges were due to the method and that in reality the probable range of V is 25–36% of TBW, of V1/V2 3.5–5.3, and of K12 30–80 ml/min. With standard values for these three parameters (V = 30% of TBW, V1/V2 = 4.4 and K12 = 55 ml/m), equal for all patients, and their respective ranges, Kt/V can be calculated with a standard deviation of 13%. Kt/V > 1.2 secures the maximum possible ß2-m removal with three HD treatments a week. Conclusions The parameters of a two-pool model of ß2-m kinetics can be derived from concentration profiles obtained under routine dialysis conditions, but accuracy is not completely satisfactory. Similar to the dialysis dose for urea (Kt/Vurea) the dialysis dose for ß2-m (Kt/Vß2-m) can be calculated from the pre- and post-dialysis concentrations of ß2-m, body weight, ultrafiltration and dialysis time. Kt/Vß2-m > 1.2 secures the maximum possible removal of ß2-m in HD with three sessions per week.

scholarly journals Development and application of a new mobile LOPAP instrument for the measurement of HONO altitude profiles in the planetary boundary layer

2009 ◽  
Vol 2 (4) ◽  
pp. 2027-2054 ◽  
Author(s):  
R. Häseler ◽  
T. Brauers ◽  
F. Holland ◽  
A. Wahner
Keyword(s):  
Nitrous Acid ◽  
Ground Level ◽  
Concentration Profiles ◽  
Mixing Ratio ◽  
Above Ground Level ◽  
Mixing Ratios ◽  
New Instrument ◽  
Mobile Measurements ◽  
Southwest Germany ◽  
Absorption Technique

Abstract. The LOPAP (long path absorption) technique has been shown to be very sensitive for the detection of nitrous acid (HONO) in the atmosphere. However, current instruments were mainly built for ground based applications. Therefore, we designed a new LOPAP instrument to be more versatile for mobile measurements and to meet the requirements for airborne application. The detection limit of the new instrument is below 1 ppt at a time resolution of 5 to 7 min. As a first test, the instrument was successfully employed during the ZEPTER-1 campaign in July 2007 on board of the Zeppelin NT airship. During 15 flights on six days we measured HONO concentration profiles over southwest Germany, predominantly in the range between 100 m and 650 m above ground level. On average, a mixing ratio of 34 ppt was observed, almost independently of height. Within a econd campaign, ZEPTER-2 in fall 2008, higher HONO mixing ratios were observed in the Lake Constance area.

scholarly journals Birds as the Feeders of Ticks (Acari, Ixodida) in Megalopolis of Kyiv

2014 ◽  
Vol 48 (5) ◽  
pp. 467-470
Author(s):  
I. V. Nebogatkin
Keyword(s):  
Developmental Stages ◽  
Urban Landscape ◽  
Parus Major ◽  
Ground Level ◽  
Urban Landscapes ◽  
Haemaphysalis Concinna ◽  
Corvus Frugilegus ◽  
Motacilla Alba ◽  
Taxonomic Groups

Abstract Birds as the Feeders of Ticks (Acari, Ixodida) in Megalopolis of Kyiv. Nebogatkin, I. V. - Data about ticks parasitizing on birds in the city of Kyiv were summarized. 117 birds and 27 nests were examined. Ticks were found on six species collecting food on the ground level: Great Tit (Parus major), White Wagtail (Motacilla alba), Rook (Corvus frugilegus), blackbird (Turdus merula), and Nuthatch (Sitta europaea). 56 Ixodidae specimens of four species from two genera were collected from the birds and their nests: Ixodes ricinus (Linnaeus, 1758); I. arboricola Schulze et Schlottke, 1930; I. lividus (Koch, 1844), Haemaphysalis concinna Koch, 1844. Th e role of birds as feeders of all developmental stages of ticks not only increases under conditions of urban landscape, but also becomes leading in the places with low population of small mammals. Ectoparasites of birds of the other taxonomic groups along with the ticks can play an important role in maintaining the circulation of pathogens of various aetiologies in the urban landscapes.

Measurements of coastal dispersion in Ontario lakes

1976 ◽  
Vol 3 (1) ◽  
pp. 156-162 ◽  
Author(s):  
Merv. D. Palmer
Keyword(s):  
Cross Sections ◽  
Coastal Waters ◽  
Relative Dispersion ◽  
Concentration Profiles ◽  
Two Dimensional ◽  
Dispersion Coefficients ◽  
Measured Concentration ◽  
Power Growth ◽  
Constant Rate ◽  
Vertical Dispersion

A series of dye injection experiments were carried out near the surface in the coastal waters of lakes Erie, Ontario, and Simcoe. The purpose of the experiments was to determine whether the relative dispersion in these regions was similar to that obtained in other oceanographical experiment. Rhodamine BA dye was injected at a constant rate (approximately 150 mg/s) at a depth 1 m below the surface from a raft anchored in 9 m of water (approximately 1.5 km offshore) for 6 to 8 h. Two-dimensional dye plume concentrations were measured at cross sections 60 to 830 m from the source. Relative dispersion coefficients were determined numerically from the measured concentration profiles. The horizontal dispersion coefficients (80 to 4100 cm2/s) were comparable to oceanographical values and exhibited a 1.33 power growth with distance from the source. Vertical dispersion coefficients were very small (less than 1 cm2/s) and relatively independent of distance from the source.

scholarly journals A MODEL OF ION TRANSPORT IN CONJUGATED POLYMERS

2009 ◽  
Vol 50 (3) ◽  
pp. 355-364
Author(s):  
JOHN BURNELL
Keyword(s):  
Ion Transport ◽  
Conjugated Polymers ◽  
Conjugated Polymer ◽  
Experimental Studies ◽  
Cation Transport ◽  
Concentration Profiles ◽  
Measured Concentration ◽  
Micro Actuator ◽  
Micro Pump ◽  
Good Agreement

AbstractUnderstanding ion transport in conjugated polymers is essential for developing mathematical models of applications of these materials. Previous experimental studies have suggested that cation transport in a conjugated polymer could be either diffusion or drift controlled, with debate over which dominates. In this paper we present a new model of cation transport that explains most of the features seen in a set of recent experiments. This model gives good agreement with measured concentration profiles, except when the profile has penetrated the polymer by more than 60%. The model shows that both diffusion and drift processes can be present. An application of a micro-actuator based on a conjugated polymer is presented to demonstrate that this technology could be used to develop a micro-pump.

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