Search results for "Mass balance"
showing 10 items of 16 documents
Calculation of the pH and the titratable acidity in clinically used infusion solutions.
2006
Clinically used infusion solutions are complex aqueous mixtures composed of a variety of different salts, acids, and non-electrolytes, and are characterized by composition, initial pH, and titratable acidity (TA). By rigorous treatment as a multi-composed acid-base system, pH and TA were calculated from proton dissociation equilibria, mass balance equations and electroneutrality condition. Nine were arbitrarily chosen as model solutions in which pH and TA were experimentally determined. From composition, and based on a set of apparent acidity constants (pK values) at 37 degrees C and total ionic strength 0.155 mol/l, pH was calculated by iteration. In the model solutions, measured pH was in…
CFD Simulation of Particle Distribution in Stirred Vessels
2000
In this work the particle concentration distribution in two-phase stirred tanks is simulated on the basis of information on the three-dimensional flow field, as obtained by numerical solution of the flow equations (CFD) using the well known k –ɛ « turbulence model. Two modelling approaches are attempted. In the simpler method the flow field is first simulated neglecting the influence of the solid phase; on the basis of the resulting flow field a very simple sedimentation model is employed for solving the solids mass balance equations in order to compute the particle concentration field. In this case no inertial effects on the solid particles are considered, so that the convective and diffus…
The Bossons glacier protects Europe's summit from erosion
2013
13 pages; International audience; The contrasting efficiency of erosion beneath cold glacier ice, beneath temperate glacier ice, and on ice-free mountain slopes is one of the key parameters in the development of relief during glacial periods. Detrital geochronology has been applied to the subglacial streams of the north face of the Mont-Blanc massif in order to estimate the efficiency of erosional processes there. Lithologically this area is composed of granite intruded at ~303 Ma within an older polymetamorphic complex. We use macroscopic features (on ~10,000 clasts) and U-Pb dating of zircon (~500 grains) to establish the provenance of the sediment transported by the glacier and its subgl…
Monitoring glacier elevation and volume changes with digital photogrammetry and GIS at Gepatschferner glacier, Austria
2006
Digital elevation models of Gepatschferner in Northern Tyrol, Austria were obtained with digital photogrammetry from high altitude stereo photo pairs and by digitizing an analogue topographic glacier map, for 1990 and 1971, respectively. A difference map was calculated to identify regions of glacier elevation increases and decreases corresponding to glacier mass gain and loss. While the glacier tongue below 2600 m showed mainly increases in glacier surface elevation as compared to 1971, the remaining glacier thickness experienced both increases and decreases. The accumulation zone above 3200 m contained several extreme cases of morphological features with altitude changes>+30 m. While the i…
Change in geometry of a high Arctic glacier to 1948 to 2013 (Austre Lovénbreen, Svalbard)
2017
International audience; The change of Austre Lovénbreen, a 4.5 km2 land-based glacier along the west coast of Spitsbergen, is investigated using geodetic methods and mass balance measurements over 1948–2013. For 2008−2013, annual mass balances computed on 36-stake measurements were obtained, in addition to annual mass balances reconstructed from the neighbouring glaciers, Midtre Lovénbreen (1968−2007) and Austre Brøggerbreen (1963−1967). The mean rate of glacier retreat for 1948–2013 is −16.7 ± 0.3 m a−1. Fluctuations in area (1948–2013 mean, −0.027 ± 0.002 km2 a−1) showed a slowing as the glacier recedes within its valley from 1990 to 1995. For 1962–2013, the average volume loss calculated…
Drawing the Materials Balance for an MBT cycle from Routine Process Measures in a Plant located in Venice
2007
An observation term was carried on in an MBT plant owned and run by a public Company to treat MSW left by separate collection. All observations and measurements were made without interfering with the ordinary operation rules, in order to assess the efficiency of one process cycle for a given batch of waste. Analytical data came from both a) process instruments and b) physical analysis of a batch of waste entering / exiting from a selected bio-cell. From the process mass losses (about 37% – including moisture evaporation – in that single process cycle) the theoretical amounts of water and carbon dioxide produced by biodegradation were calculated. A verification of the results was tried throu…
The biogeochemical cycle of mercury in the Augusta Bay
2014
Mercurial, the metaphor for volatile unpredictable behavior, aptly reflects the complexities of one of the most insidiously interesting and scientifically challenging biogeochemical cycles at the Earth’s surface. At the base of this toxic metal cycle there is the conversion between the different Hg chemical species, in which the balance between the reduced and oxidized forms depends primary on redox system conditions. The potential risks of human exposure to Hg, especially in the form of monomethylmercury (MMHg), particularly prenatally, and the potential deleterious ecological consequences from localized to global scale Hg pollution, have given much impetus to mercury studies and regulator…
Evaluation of methane emissions from Palermo municipal landfill: Comparison between field measurements and models
2010
Methane (CH(4)) diffuse emissions from Municipal Solid Waste (MSW) landfills represent one of the most important anthropogenic sources of greenhouse gas. CH(4) is produced by anaerobic biodegradation of organic matter in landfilled MSW and constitutes a major component of landfill gas (LFG). Gas recovery is a suitable method to effectively control CH(4) emissions from landfill sites and the quantification of CH(4) emissions represents a good tool to evaluate the effectiveness of a gas recovery system in reducing LFG emissions. In particular, LFG emissions can indirectly be evaluated from mass balance equations between LFG production, recovery and oxidation in the landfill, as well as by a d…
Modeling of perched leachate zone formation in municipal solid waste landfills.
2010
The paper presents a 1D mathematical model for the simulation of the percolation fluxes throughout a landfill for municipal solid waste (MSW). Specifically, the model was based on mass balance equations, that enable simulation of the formation of perched leachate zones in a landfill for MSW. The model considers the landfill divided in several layers evaluating the inflow to and outflow from each layer as well as the continuous moisture distribution. The infiltration flow was evaluated by means of the Darcy’s law for an unsaturated porous medium, while the moisture distribution evaluation has been carried out on the basis of the theory of the vertically distributed unsaturated flow. The solu…
Energy and environmental analysis of marble productive sites: «by phases» and «by single process» combined approach
2018
Energy Procedia 00 (20 1 8 ) 000 – 000 73rd Conference of the Italian Thermal Machines Engineering Association, ATI 2018, Pisa, Italy, 12 Sep 2018 - 14 Sep 2018; Italy : Elsevier Ltd. (2018).