Effect of Point and Diffuse Source Loadings on Mercury Concentrations in the Wabigoon River: Evidence of a Seasonally Varying Sediment–Water Partition

1986 ◽  
Vol 43 (7) ◽  
pp. 1426-1444 ◽  
Author(s):  
J. W. Parks ◽  
J. A. Sutton ◽  
A. Lutz
Keyword(s):  
Suspended Solids ◽  
Surface Sediments ◽  
Suspended Sediments ◽  
Mean Value ◽  
Control Site ◽  
Diffuse Source ◽  
Order Of Magnitude ◽  
Summer Temperatures ◽  
High Flows ◽  
The Mean

Ten years after major mercury loadings from a chlor-alkalai plant were sharply reduced, mercury levels in the surface sediments, water, and suspended sediments of the Wabigoon River downstream of Dryden, Ontario, remain markedly elevated. During 1979, a typical water year, average mercury concentrations in water throughout an 80-km reach were nearly five times the mean value at the control site. Elevated mercury levels in the Wabigoon River are primarily due to the chemical and biological remobilization of mercury from sediments. Lesser amounts are due to the erosion of mercury-enriched sediments during high flows and to current releases from the mill site at Dryden. In the absence of resuspended sediment during high flows, mercury levels in contaminated waters can be best described by a sediment – water – suspended solids partition. This condition was established within half a day in the most contaminated portion of the system. Mercury concentrations in water can fluctuate seasonally by an order of magnitude. Highest concentrations were associated with elevated summer temperatures.

Liquid helium films. I. The thickness of the film

1950 ◽  
Vol 203 (1072) ◽  
pp. 119-132 ◽  
Keyword(s):  
Liquid Helium ◽  
Dynamic Method ◽  
Mean Value ◽  
Helium Films ◽  
Helium Ii ◽  
Experimental Factor ◽  
Order Of Magnitude ◽  
The Mean

The thickness ( d ) of the helium II film and its variation with height ( H ) and temperature were measured by a dynamic method involving the oscillations of a meniscus in a capillary. The variation with height could be represented only approximately by the equation d = k/H n , as the effective value of n was greater at smaller values of H . The mean value of n over a range of heights from 0·5 to 5 cm. was 0·14, which is appreciably smaller than the values predicted by the theories so far advanced to explain the formation of the film. The order of magnitude of k was 2 x 10 -6 cm., but it varied slightly with the nature of the surface or some other experimental factor.

scholarly journals On the Accuracy of Error Propagation Calculations by Analytic Formulas Obtained for the Inverse Transformation

2019 ◽  
Vol 64 (3) ◽  
pp. 217
Author(s):  
V. I. Romanenko ◽  
N. V. Kornilovska
Keyword(s):  
Error Propagation ◽  
Random Variable ◽  
Mean Value ◽  
Inverse Transformation ◽  
First Order ◽  
Order Of Magnitude ◽  
The Mean ◽  
Normally Distributed

The accuracy of error propagation calculations is estimated for the transformation x → y = f(x) of the normally distributed random variable x. The estimation is based on the formulas for the error propagation obtained for the inverse transformation y → x of the normally distributed random variable y. In the general case, the calculation accuracy for the mean value and the variance of the random variable y is shown to be of the first order of magnitude in the variance of the random variable x.

An Alternative Approach for Computation of Annual Toxic Contaminant Loadings in Urban Runoff

1994 ◽  
Vol 29 (1) ◽  
pp. 75-88
Author(s):  
P. Xu ◽  
J. Marsalek ◽  
I.K. Tsanis
Keyword(s):  
Suspended Solids ◽  
Urban Runoff ◽  
Regression Method ◽  
Alternative Approach ◽  
Order Of Magnitude ◽  
Load Component ◽  
The Mean ◽  
Mean Concentration ◽  
Storm Model ◽  
Whole Water

Abstract An alternative approach was presented for estimating annual toxic contaminant loadings in urban runoff. In this method, the mean contaminant concentrations are calculated by a regression method. In the computation of contaminant loadings, the load component transported by the liquid phase was estimated by multiplying the mean concentration in water by the runoff volume simulated by the STORM model. The load component transported by suspended solids was calculated by multiplying the mean concentration in solids by the event mean solids concentrations reported in the NURP Program. The loadings calculated by this method were compared with those obtained from whole water samples, and the differences are within an order of magnitude. Since more parameters are used in this approach, it appears more suitable for use in sensitivity analysis of parameters, and more flexible in evaluations of controls measures.

Phosphorus and Metal Contaminant Transport in Two Southern Ontario Rivers: the Grand River and its Tributary, the Nith River

1996 ◽  
Vol 31 (1) ◽  
pp. 119-152 ◽  
Author(s):  
T. Mayer ◽  
E. Delos Reyes
Keyword(s):  
Heavy Metals ◽  
Water Quality ◽  
Great Lakes ◽  
Total Phosphorus ◽  
Water Samples ◽  
Suspended Solids ◽  
Suspended Sediments ◽  
Southern Ontario ◽  
High Flows ◽  
Grand River

Abstract Water samples and suspended sediments from two southern Ontario rivers, the Grand River and its tributary, the Nith River, were analyzed to investigate the role of suspended sediments in the transport of phosphorus and metals from tributaries. Water samples were analyzed for total suspended solids, total phosphorus, total dissolved phosphorus, chloride and heavy metal concentrations. Suspended sediments were analyzed for forms of phosphorus, total and organic carbon, and heavy metals. Concentrations of total phosphorus and heavy metals in water were elevated during high flows (spring snowmelt and episodes of intensive rain events), which are characterized by high concentrations of suspended solids. On average, about half of the total phosphorus in the water (60 and 54% in the Grand and Nith rivers, respectively) was transported in the particulate form, of which about 20% is in a form that would be potentially available for biological utilization upon depletion of soluble P. Biologically inert apatite-P accounted for 25 and 19% of the total particulate P in suspended sediments from the Grand and Nith rivers, respectively, indicating that between one-fifth and one-quarter of the tributary particulate P flux is of little environmental significance. This form of particulate P showed positive correlation with discharge, indicating increased contribution of this form of P during high flows due to the channel scouring and bank erosion. This finding has important implications for the refinement of P load calculations, since it is during the wet years that P loads to the Great Lakes exceed target loads stipulated by the Great Lakes Water Quality Agreement, mainly because of increased tributary P contributions. Except for apatite-P in suspended sediments from the Grand River, no statistically significant intersite differences were found in water and sediment chemistry, suggesting that there are no important sources or sinks of available phosphorus and metals between the monitored sites. River inputs from sewage treatment plants and urban runoff appear to have little effect on water quality. The lack of significant site differentiation in suspended sediments chemistry also reflects the absence of any significant chemical and/or biological processing of particles in transit and the similarity of sediment sources.

PROTEIN-BOUND IODINE IN INFANTS FROM BIRTH TO ONE YEAR OF AGE

PEDIATRICS ◽  
1951 ◽  
Vol 7 (2) ◽  
pp. 240-244
Author(s):  
T. S. DANOWSKI ◽  
S. Y. JOHNSTON ◽  
W. C. PRICE ◽  
M. MCKELVY ◽  
S. S. STEVENSON ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Maternal Blood ◽  
Mean Value ◽  
Elevated Concentration ◽  
Older Children ◽  
Mean Values ◽  
Order Of Magnitude ◽  
The Mean ◽  
One Year ◽  
Relationship Of

Statistical comparisons indicate that within 12 hours of birth the serum protein-bound iodine of the infant is of the same order of magnitude, on the average, as that present in maternal blood during pregnancy or within a few hours of delivery. During the remainder of the first week of life there occurs a transient statistically significant increase in the mean value of this iodine fraction. During the sixth to twelfth week the concentrations fall below those present neonatally, but at this time or at any subsequent age up to 1 year, they are still on the average above those encountered in euthyroid nonpregnant adults or in older children. The possible relationship of these higher mean values in infancy to increased thyroid function in the rapidly growing infant have been mentioned with emphasis on the elevated concentration of circulating thyroxin.

scholarly journals The relative importance of macrophysical and cloud albedo changes for aerosol induced radiative effects in stratocumulus

2016 ◽  
Author(s):  
Daniel P. Grosvenor ◽  
Paul R. Field ◽  
Adrian A. Hill ◽  
Benjamin J. Shipway
Keyword(s):  
Mean Value ◽  
Cloud Microphysics ◽  
Liquid Water Path ◽  
Frequency Distributions ◽  
Cloud Albedo ◽  
Aerosol Loading ◽  
Stratocumulus Clouds ◽  
Order Of Magnitude ◽  
The Mean ◽  
The Impact

Abstract. Aerosol-cloud interactions are explored using 1 km resolution simulations of SE Pacific stratocumulus clouds that include realistic meteorology along with newly implemented cloud microphysics and sub-grid cloud schemes. The model was critically assessed against observations of Liquid Water Path (LWP), broadband fluxes, cloud fraction (fc), droplet number concentrations (Nd) and radar reflectivities. Aerosol loading sensitivity tests showed that at low aerosol loadings, changes to aerosol affected shortwave fluxes equally through changes to cloud macrophysical charateristics (LWP, fc) and cloud albedo changes due solely to Nd changes. However, at high aerosol loadings, only the Nd albedo change was important. Evidence was also provided to show that a treatment of sub-grid clouds is as important as order of magnitude changes in aerosol loading for the accurate simulation of stratocumulus at this grid resolution. Overall, the control model demonstrated a credible ability to reproduce observations suggesting that many of the important physical processes for accurately simulating these clouds are represented within the model and giving some confidence in the predictions of the model concerning stratocumulus and the impact of aerosol. For example, the control run was able to reproduce the shape and magnitude of the observed diurnal cycle of domain mean LWP to within ~ 10 g m−2 for the nighttime, but with an overestimate for the daytime of up to 30 g m−2. The latter was attributed to the uniform aerosol fields imposed on the model, which meant that the model failed to include the low Nd mode that was observed further offshore, preventing the LWP removal through precipitation that likely occurred in reality. The boundary layer was too low by around 260 m, which was attributed to the driving global model analysis. The shapes and sizes of the observed bands of clouds and open-cell-like regions of low areal cloud cover were qualitatively captured. The daytime fc frequency distribution was reproduced to within fc = 0.04 for fc > ~ 0.7 as was the domain mean nighttime fc (at a single time) to within fc = 0.02. Frequency distributions of shortwave top-of-the-atmosphere (TOA) fluxes from satellite were well represented by the model with only a slight underestimate of the mean by 15 %; this was attributed to near--shore aerosol concentrations that were too low for the particular times of the satellite overpasses. TOA longwave flux distributions were close to those from satellite with agreement of the mean value to within 0.4 %. From comparisons of Nd distributions to those from satellite it was found that the Nd mode from the model agreed with the higher of the two observed modes to within ~ 15 %.

scholarly journals Automatic Tolerance Analysis of Permanent Magnet Machines with Encapsuled FEM Models Using Digital-Twin-Distiller

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 2077
Author(s):  
Tamás Orosz ◽  
Krisztián Gadó ◽  
Mihály Katona ◽  
Anton Rassõlkin
Keyword(s):  
Tolerance Analysis ◽  
Mean Value ◽  
System Level ◽  
Electrical Machine ◽  
Permanent Magnet Machines ◽  
Fem Model ◽  
Cogging Torque ◽  
Order Of Magnitude ◽  
Manufacturing Tolerances ◽  
The Mean

Tolerance analysis is crucial in every manufacturing process, such as electrical machine design, because tight tolerances lead to high manufacturing costs. A FEM-based solution of the tolerance analysis of an electrical machine can easily lead to a computationally expensive problem. Many papers have proposed the design of experiments, surrogate-model-based methodologies, to reduce the computational demand of this problem. However, these papers did not focus on the information loss and the limitations of the applied methodologies. Regardless, the absolute value of the calculated tolerance and the numerical error of the applied numerical methods can be in the same order of magnitude. In this paper, the tolerance and the sensitivity of BLDC machines’ cogging torque are analysed using different methodologies. The results show that the manufacturing tolerances can have a significant effect on the calculated parameters, and that the mean value of the calculated cogging torque increases. The design of the experiment-based methodologies significantly reduced the calculation time, and shows that the encapsulated FEM model can be invoked from an external system-level optimization to examine the design from different aspects.

PARTICLE PRODUCTION BY THE FORMATION OF A GLOBAL MONOPOLE

1991 ◽  
Vol 06 (20) ◽  
pp. 3613-3623 ◽  
Author(s):  
CARLOS O. LOUSTO
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Gravitational Field ◽  
Scalar Field ◽  
Particle Production ◽  
Mean Value ◽  
Global Symmetry ◽  
Global Monopole ◽  
Order Of Magnitude ◽  
The Mean

We study pair production by the changing gravitational field of a global monopole during its formation in the very early universe after the breaking of a global symmetry. We obtain a result of the same order of magnitude as in the case of gauge strings ρ~(Gη2)2/τ4, where η is the mean value of the scalar field and τ is the time at which the phase transition occurs. We also discuss how a global monopole inside a mini-black-hole affects its final stages of evolution. We find that neither the Hawking temperature nor the entropy-area relation is essentially modified by the presence of the monopole.

scholarly journals Biharmonic Attractors of Internal Gravity Waves

2021 ◽  
Vol 56 (3) ◽  
pp. 403-412
Author(s):  
D. A. Ryazanov ◽  
M. I. Providukhina ◽  
I. N. Sibgatullin ◽  
E. V. Ermanyuk
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Large Time ◽  
Internal Gravity Waves ◽  
Wave Pattern ◽  
Mean Value ◽  
Order Of Magnitude ◽  
The Mean ◽  
Low Amplitude ◽  
Large Time Scale

Abstract— The hydrodynamic system that admits the development of internal wave attractors under biharmonic forcing is investigated. It is shown that in the case of low amplitude of external forcing the wave pattern consists of two attractors that interact between themselves only slightly: the total energy of the system is equal to the sum of energies of the components with high accuracy. In the nonlinear case the attractors interact in the more complex way which leads to the development of a cascade of triad interactions generating a rich set of time scales. In the case of closely adjacent frequencies of the components of a biharmonic perturbation, the nonlinear “beating” regime develops, namely, the mean energy of the system of coupled attractors performs oscillations at a large time scale that corresponds to the beating period. It is found that the high-frequency energy fluctuations corresponding to the same mean energy can differ by an order of magnitude depending on whether the envelope of the mean value increases or decreases.

Long-period modulated superstructures in Pd-12.5 at.%Ce and Pd-15 at.%Ce alloys

1990 ◽  
Vol 48 (4) ◽  
pp. 164-165
Author(s):  
Noriyuki Kuwano ◽  
Masaru Itakura ◽  
Kensuke Oki
Keyword(s):  
Electron Microscopy ◽  
Mean Value ◽  
Heavy Elements ◽  
Arc Furnace ◽  
X Ray ◽  
Long Period ◽  
Ultra High Purity ◽  
Heat Treated ◽  
Atomic Scattering ◽  
The Mean

Pd-Ce alloys exhibit various anomalies in physical properties due to mixed valences of Ce, and the anomalies are thought to be strongly related with the crystal structures. Since Pd and Ce are both heavy elements, relative magnitudes of (fcc-fpd) are so small compared with <f> that superlattice reflections, even if any, sometimes cannot be detected in conventional x-ray powder patterns, where fee and fpd are atomic scattering factors of Ce and Pd, and <f> the mean value in the crystal. However, superlattices in Pd-Ce alloys can be analyzed by electron microscopy, thanks to the high detectability of electron diffraction. In this work, we investigated modulated superstructures in alloys with 12.5 and 15.0 at.%Ce.Ingots of Pd-Ce alloys were prepared in an arc furnace under atmosphere of ultra high purity argon. The disc specimens cut out from the ingots were heat-treated in vacuum and electrothinned to electron transparency by a jet method.

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