9,805 research outputs found
Case study: design, operation and water quality management of a combined wet and dry pond system
Pond structures as cost-effective water treatment, storage and âsource controlâ drainage techniques can be applied in order to reduce wastewater treatment costs, produce water for subsequent recycling and reduce the risk of downstream flooding. However, there is a need for detailed
design, operation and maintenance data. The purpose of this study was to optimise design and operation guidelines, and to assess the water treatment potential of stormwater
pond systems. Performance data (15 months) for a stormwater pond pilot plant were collected. The system is based on a combined silt trap, attenuation wet pond and dry pond system
applied for drainage of roof water run-off from a single domestic property. United Kingdom Building Research Establishment and Construction Industry Research and Information Association, and German Association for Water, Wastewater and Waste design guidelines were tested. These design guidelines were insufficient because they do not consider local hydrological and soil conditions. The infiltration function for the dry pond is logarithmic and depends on the season. Furthermore, biochemical and physical algal control techniques were successfully applied, and passive water treatment of rainwater run-off with a wet pond was found to be sufficient. However, seasonal and diurnal variations of biochemical oxygen demand, dissolved oxygen and pH were recorded. Finally, capital and labour costs for small ponds are high
Total and partial cross sections of the Sn()Te reaction measured via in-beam -ray spectroscopy
An extended database of experimental data is needed to address uncertainties
of the nuclear-physics input parameters for Hauser-Feshbach calculations.
Especially +nucleus optical model potentials at low energies are not
well known. The in-beam technique with an array of high-purity germanium (HPGe)
detectors was successfully applied to the measurement of absolute cross
sections of an (,) reaction on a heavy nucleus at sub-Coulomb
energies. The total and partial cross-section values were measured by means of
in-beam -ray spectroscopy. Total and partial cross sections were
measured at four different -particle energies from
MeV to MeV. The measured total cross-section values are in
excellent agreement with previous results obtained with the activation
technique, which proves the validity of the applied method. The experimental
data was compared to Hauser-Feshbach calculations using the nuclear reaction
code TALYS. A modified version of the semi-microscopic +nucleus optical
model potential OMP 3, as well as modified proton and widths, are
needed in order to obtain a good agreement between experimental data and
theory. It is found, that a model using a local modification of the
nuclear-physics input parameters simultaneously reproduces total cross sections
of the Sn(,) and Sn(,p) reactions. The
measurement of partial cross sections turns out to be very important in this
case in order to apply the correct -ray strength function in the
Hauser-Feshbach calculations. The model also reproduces cross-section values of
-induced reactions on Cd, as well as of (,n) reactions
on Sn, hinting at a more global character of the obtained
nuclear-physics input.Comment: 8 pages, 9 figure
Comparison of planted soil infiltration systems for treatment of log yard runoff
Treatment of log yard runoff is required to avoid
contamination of receiving watercourses. The research aim was to assess
if infiltration of log yard runoff through planted soil systems is successful
and if different plant species affect the treatment performance at a fieldscale
experimental site in Sweden (2005 to 2007). Contaminated runoff
from the log yard of a sawmill was infiltrated through soil planted with
Alnus glutinosa (L.) Gašrtner (common alder), Salix schwerinii3viminalis
(willow variety ââGudrunââ), Lolium perenne (L.) (rye grass), and Phalaris
arundinacea (L.) (reed canary grass). The study concluded that there were
no treatment differences when comparing the four different plants with
each other, and there also were no differences between the tree and the
grass species. Furthermore, the infiltration treatment was effective in
reducing total organic carbon (55%) and total phosphorus (45%)
concentrations in the runoff, even when the loads on the infiltration
system increased from year to year
An Introduction to Slice-Based Cohesion and Coupling Metrics
This report provides an overview of slice-based software metrics. It brings together information about the development of the metrics from Weiserâs original idea that program slices may be used in the measurement of program complexity, with alternative slice-based measures proposed by other researchers. In particular, it details two aspects of slice-based metric calculation not covered elsewhere in the literature: output variables and worked examples of the calculations. First, output variables are explained, their use explored and standard reference terms and usage proposed. Calculating slice-based metrics requires a clear understanding of âoutput variablesâ because they form the basis for extracting the program slices on which the calculations depend. This report includes a survey of the variation in the definition of output variables used by different research groups and suggests standard terms of reference for these variables. Our study identifies four elements which are combined in the definition of output variables. These are the function return value, modified global variables, modified reference parameters and variables printed or otherwise output by the module. Second, slice-based metric calculations are explained with the aid of worked examples, to assist newcomers to the field. Step-by-step calculations of slice-based cohesion and coupling metrics based on the vertices output by the static analysis tool CodeSurfer (R) are presented and compared with line-based calculations
Wavelength dependence of angular diameters of M giants: an observational perspective
We discuss the wavelength dependence of angular diameters of M giants from an
observational perspective. Observers cannot directly measure an optical-depth
radius for a star, despite this being a common theoretical definition. Instead,
they can use an interferometer to measure the square of the fringe visibility.
We present new plots of the wavelength-dependent centre-to-limb variation (CLV)
of intensity of the stellar disk as well as visibility for Mira and non-Mira M
giant models. We use the terms ``CLV spectra'' and ``visibility spectra'' for
these plots. We discuss a model-predicted extreme limb-darkening effect (also
called the narrow-bright-core effect) in very strong TiO bands which can lead
to a misinterpretation of the size of a star in these bands. We find no
evidence as yet that this effect occurs in real stars. Our CLV spectra can
explain the similarity in visibilities of R Dor (M8IIIe) that have been
observed recently despite the use of two different passbands. We compare
several observations with models and find the models generally under-estimate
the observed variation in visibility with wavelength. We present CLV and
visibility spectra for a model that is applicable to the M supergiant alpha
Ori.Comment: 16 pages with figures. Accepted by MNRA
Pulsation of M-type Mira variables with moderately different mass: search for observable mass effects
Models of M-type Miras with masses of 1 and 1.2 , i.e.
with envelope masses of about 0.4 and 0.6 , have been
constructed, and a comparison has been made of their observable properties.
Geometric pulsation of continuum-forming layers is found to be little affected
by the mass difference. The influence of molecular contamination of
near-infrared continuum bandpasses upon interferometrically measured fit
diameters ranges from undetectable to quite significant. Some pulsation cycles
of the lower-mass model Mira show substantially stronger contamination than
that found in any cycle of the higher-mass star. Observations which sample
pulsation phase well and continuously are crucial for avoiding
misinterpretations, because the assignment of absolute pulsation phases is
inherently uncertain by at least 0.1 cycles, diameter changes may be strongly
phase-dependent, and cycle-to-cycle variations may be substantial. In accord
with expectations, we find that cycle-to-cycle variations that show up in light
curves and in near-continuum diameters tend to be larger and more common in the
low-mass models, leading to one possible way to discriminate mass. Two other
methods, based on high-precision measurements of the pulsation amplitude and on
derivation of pre-maximum effective temperatures from diameter measurements,
are also discussed. High-layer features that may be strongly affected by mass
are not well described by present dust-free models.Comment: Accepted for MNRAS, 8 Pages, 8 Figure
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