1,757 research outputs found
Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherlands
Geochemical reactivity of subsurface sediments as potential buffer to anthropogenic inputs: a strategy for regional characterization in the Netherland
Доповнення до Списку дійсних членів УМТ
Grondwater is wereldwijd de grootste bron van zoet water, en in
Nederland hebben we er relatief veel van. Dat heeft te maken met de
unieke ligging in een deltagebied waarin dikke pakketten goed doorlatende
afzettingen zoals fluviatiele zanden zijn afgezet, met een aanzienlijk
neerslagoverschot en met de aanvoer van zoet rivierwater dat
deels weer infiltreert. Toch is het ook in Nederland zaak om met het
grondwater zorgvuldig om te springen
Proposed guideline for modelling water demand by suburb
This study investigated factors affecting the average domestic water demand of a large number of suburbs in South Africa. Suburbs form an ideal demand grouping since they tend to have similar stand areas, climatic conditions and user characteristics. In addition, since properties within a suburb are close to one another, it may be reasonably assumed that differences in user demands will cancel one another out so that a designer only has to cater for the average demand of the suburb. A database on measured domestic water demands was used to determine the average of the Annual Average Daily Demand (AADD) for a large number of suburbs in South Africa (i.e. the average AADD per suburb), and this data was linked to census and climate data. The combined data set was then subjected to various regression analyses to identify the most important influencing factors. Stand area was found to be the most important influencing factor, validating the approach followed by the current South African design guidelines. However, the current guidelines were found to exclude a large number of measured data points, and thus a new, more comprehensive design envelope is proposed
Recommended from our members
FABRIC: A National-Scale Programmable Experimental Network Infrastructure
FABRIC is a unique national research infrastructure to enable cutting-edge and exploratory research at-scale in networking, cybersecurity, distributed computing and storage systems, machine learning, and science applications. It is an everywhere-programmable nationwide instrument comprised of novel extensible network elements equipped with large amounts of compute and storage, interconnected by high speed, dedicated optical links. It will connect a number of specialized testbeds for cloud research (NSF Cloud testbeds CloudLab and Chameleon), for research beyond 5G technologies (Platforms for Advanced Wireless Research or PAWR), as well as production high-performance computing facilities and science instruments to create a rich fabric for a wide variety of experimental activities
Сучасні глобальні процеси у світовій економіці та їх вплив на економічну безпеку держави
Мета роботи. Визначення особливостей формування системи економічної безпеки держави, взагалі, та
України, зокрема, в сучасних умовах глобального розвитку світового господарства
A theory of normed simulations
In existing simulation proof techniques, a single step in a lower-level
specification may be simulated by an extended execution fragment in a
higher-level one. As a result, it is cumbersome to mechanize these techniques
using general purpose theorem provers. Moreover, it is undecidable whether a
given relation is a simulation, even if tautology checking is decidable for the
underlying specification logic. This paper introduces various types of normed
simulations. In a normed simulation, each step in a lower-level specification
can be simulated by at most one step in the higher-level one, for any related
pair of states. In earlier work we demonstrated that normed simulations are
quite useful as a vehicle for the formalization of refinement proofs via
theorem provers. Here we show that normed simulations also have pleasant
theoretical properties: (1) under some reasonable assumptions, it is decidable
whether a given relation is a normed forward simulation, provided tautology
checking is decidable for the underlying logic; (2) at the semantic level,
normed forward and backward simulations together form a complete proof method
for establishing behavior inclusion, provided that the higher-level
specification has finite invisible nondeterminism.Comment: 31 pages, 10figure
Measurement of the EMC effect in the deuteron
We determined the structure function ratio R-EMC(d) = F-2(d)/(F-2(n) + F-2(p)) from recently published F-2(n)/F-2(d) data taken by the BONuS experiment using CLAS at Jefferson Lab. This ratio deviates from unity, with a slope dR(EMC)(d)/dx=-0.10 +/- 0.05 in the range of Bjorken x from 0.35 to 0.7, for invariant mass W \u3e 1.4 GeV and Q(2) \u3e 1GeV(2). The observed EMC effect for these kinematics is consistent with conventional nuclear physics models that include off-shell corrections, as well as with empirical analyses that find the EMC effect proportional to the probability of short-range nucleon-nucleon correlation
Документи Державного архіву Чернігівської області як джерело захисту прав жертв нацистського окупаційного режиму
The retention of phosphorus in surface waters through co-precipitation of
phosphate with Fe-oxyhydroxides during exfiltration of anaerobic Fe(II) rich
groundwater is not well understood. We developed an experimental field
set-up to study Fe(II) oxidation and P immobilization along the flow-path
from groundwater into surface water in an agricultural experimental
catchment of a small lowland river. We physically separated tube drain
effluent from groundwater discharge before it entered a ditch in an
agricultural field. Through continuous discharge measurements and weekly
water quality sampling of groundwater, tube drain water, exfiltrated
groundwater, and surface water, we investigated Fe(II) oxidation kinetics
and P immobilization processes. The oxidation rate inferred from our field
measurements closely agreed with the general rate law for abiotic oxidation
of Fe(II) by O<sub>2</sub>. Seasonal changes in climatic conditions affected the
Fe(II) oxidation process. Lower pH and lower temperatures in winter
(compared to summer) resulted in low Fe oxidation rates. After exfiltration
to the surface water, it took a couple of days to more than a week before
complete oxidation of Fe(II) is reached. In summer time, Fe oxidation rates
were much higher. The Fe concentrations in the exfiltrated groundwater were
low, indicating that dissolved Fe(II) is completely oxidized prior to inflow
into a ditch. While the Fe oxidation rates reduce drastically from summer to
winter, P concentrations remained high in the groundwater and an order of
magnitude lower in the surface water throughout the year. This study shows
very fast immobilization of dissolved P during the initial stage of the
Fe(II) oxidation process which results in P-depleted water before Fe(II) is
completely depleted. This cannot be explained by surface complexation of
phosphate to freshly formed Fe-oxyhydroxides but indicates the formation of
Fe(III)-phosphate precipitates. The formation of Fe(III)-phosphates at redox
gradients seems an important geochemical mechanism in the transformation of
dissolved phosphate to structural phosphate and, therefore, a major control
on the P retention in natural waters that drain anaerobic aquifers
- …