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Gedye, Sharon Jane. "Mass balance in recent peats." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266139.
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Andersson, Emil. "Online Metallurgical Mass Balance and Reconciliation." Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185252.
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In mineral processing, one of the most important and versatile separation methods is flotation. Flotation utilizes the different surface properties of the valuable minerals in the ore to separate them from the less valuable gangue material in the ore. Crushed and ground ore is mixed with water and fed into flotation tanks. In the flotation tanks, the particles of valuable mineral are made hydrophobic. That way, they can be floated by attaching to air bubbles and gather on top of the flotation tank as froth. This froth, containing higher concentrations of valuable mineral, is recovered and then processed further. The flotation circuit is controlled and maintained using measurements on the mass flows and grades of different materials. Due to economical, practical, and technological limitations, these measurements are performed at a chosen number of points in the circuit and at discrete points in time. Poor measurement data can have devastating consequences if the operators are left with limited information and errors in the circuit remain undetected. The accuracy of the acquired measurements is improved by performing mass balance and reconciliation. Traditionally, mass balance uses the sum of the total mass flows and the average grades over long times to avoid including the internal mass of the circuit in the calculations. It is desirable to perform mass balance directly to allow for faster intervention if any failures occur in the circuit during the on-line process. This report describes an on-line dynamic approach towards mass balancing and reconciliation of the mass flows and grades in a flotation circuit. Here, physical models of the flotation circuit are used to construct mass balance constraints using interpolation and test functions and the mass balance problem is posed as an optimization problem. The optimization problem is to adjust the assay such that the residual, the difference between the measured and the adjusted assay, is minimized while maintaining mass balance. An implementation in MATLAB and tests on synthetic data show that the dynamic formulation of mass balance does adjust 'erroneous' measurements such that mass balance is fulfilled. Given this result, there are still important aspects of the implementation that have to be addressed. The model uses the unknown and cell specific parameters flotation rate and recovery. Thus, these must be found or properly modeled. This report proposes a possible model for flotation rate as well as a strategy to find the recovery. The requirements of accuracy and speed of the implementation are also discussed. Possible next steps of this project is to further confirm a time effective implementation using synthetic data. Consequently, the implementation can be adapted for natural data in order to verify correctness of models.I malmanrikning, är flotation en av de viktigaste och mest mångsidiga metoderna. Flotation utnyttjar de fysikaliska ytegenskaperna som partiklar av värdemineral har för att separera dessa från det mindre värdefulla gråberget i malmen. Krossad och mald malm blandas med vatten och matas in i flotationstankar. I flotationstankarna görs partiklarna av värdemineral hydrofobiska. På så vis kan de fästa sig vid luftbubblor och flyta till ytan och bilda ett skum. Detta skum samlas sedan ihop och behandlas vidare eftersom det innehåller en högre koncentration av värdemineral. Flotationskretsen styrs och underhålls med hjälp av mätningar av massflödena och halterna av de olika ämnena som finns i kretsen. På grund av ekonomiska, praktiska, och teknologiska hinder kan dessa mätningar bara göras på ett utvalt antal punkter i kretsen samt bara vid diskreta tillfällen. Felaktigt data kan ha förödande konsekvenser om operatörerna lämnas med begränsad information och processen fortlöper med oupptäckta fel. Mätsäkerheten kan förbättras med hjälp av massbalansering och haltjustering. Traditionellt görs massbalansering genom att summera den totala massan som löpt genom kretsen samt medelvärden av halterna över lång tid för att undvika att räkna in den interna massan i systemet. Det är önskvärt att utföra massbalansering direkt för att möjliggöra snabbare ingrepp ifall fel uppstår i kretsen under den fortlöpande processen. Denna rapport beskriver en dynamisk lösning för massbalansering och justering av massflöden och halter i en flotationskrets. Här används fysikaliska modeller av kretsen för att konstruera bivillkor för massbalans med hjälp utav interpolation och testfunktioner och massbalanseringsproblemet ställs upp som ett optimeringsproblem. Optimeringen sker genom att justera mätserien så att residualen, skillnaden mellan det uppmätta värdet och det justerade värdet, minimeras under uppfyllande av mass balans. En implementation i MATLAB och tester på syntetisk data visar att den dynamiska formuleringen av massbalans justerar de felaktiga mätvärdena så att massbalans uppfylls. Med det resultatet i åtanke, finns det fortfarande viktiga aspekter av implementationen som bör tas hänsyn till. Modellen använder de okända och cellspecifika parametrarna flotationshastighet och utbytet och dessa måste kunna bestämmas för att denna modell ska kunna användas. Ett förslag på modellering av flotationshastigheten föreslås i rapporten. Dessutom ges förslag på strategier att hitta utbytet. Kraven på noggrannhet och snabbhet diskuteras också. Möjliga nästa steg för projektet är att vidareutveckla en tidseffektiv implementation genom att använda syntetiska data. Därefter kan en implementation för naturligt data verifiera modellerna.
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au, taiga@westnet com, and John Rich. "Integrated Mass, Solute, Isotopic and Thermal Balances of a Coastal Wetland." Murdoch University, 2004. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040520.130717.
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Mass, solute (chloride), isotope (deuterium) and thermal balances were completed at Perry Lakes, two semi-permanent 'water table' lakes near Perth, Western Australia. All balance components except groundwater discharge/recharge were measured independently. These difficult to measure groundwater components of lake-aquifer interaction were estimated by integrating mass, solute and chloride data in sequential 4 day balances spanning two years. Before urbanisation, such wetlands functioned predominantly as flow-through lakes. Now, large winter storm water inputs (and summer artificial level maintenance pumped locally from groundwater) dominate. In East Lake these inputs together comprise 42% of the annual water budget; groundwater discharge is reduced to just 2%. Even under flow-through conditions, these 'non natural' inputs are so large East Lake always tends towards a recharge state and commonly becomes a local groundwater mound. Flow-through is established in both lakes over winter. Initially each lake functions separately however as winter progresses shared capture and release zones are established. Maintenance of lake levels in early summer forces East Lake back to recharge status.
Sediment heat flux (Qse) is significant in these very shallow lakes. Over summer Qse was negative, with a net movement of heat from the water into the sediments which act as a seasonal heat sink. In winter Qse was positive and stored summer heat was returned to the water column. This flux at times exceeded 40 W m-2. Evaporation was determined independently by floating pan, leaving Qse as the thermal balance residual. Ignoring Qse, annual evaporation determined by thermal balance was over estimated by 7%. Over and under estimates of individual 12 day balance period evaporation exceeded 50%.
Monthly Class A (Perth airport) pan coefficients varied from 0.54 (January) to 0.86 (September). Ten empirical equations for evaporation were calibrated and compared with the East Lake floating pan. Best performer was the Makkink which tracked the floating pan closely throughout all seasons. Poorest were the Penman, DeBruin-Keijman, Priestly-Taylor and Brutsaert-Stricker which grossly over estimated late winter evaporation. Transpiration from Typha orientalis, estimated using hydrograph techniques was 43% of open water evaporation in summer and 28% annually. Temperature controlled evaporation pans (tracking lake temperature) experimentally determined the local deuterium content of lake evaporate ÔE, required for isotopic balances. Techniques employing pans evaporated to dryness and pans evaporated at constant volume were run in tandem continuously for two years.
This study singularly integrates mass, solute and isotope balances thereby allowing groundwater components to be accurately quantified. The isotope balances are unique, being the only such balances incorporating experimentally derived local deuterium values of lake evaporate. This study represents the only thermal balance, the only accurate determination of pan-lake coefficients and the first calibration of commonly used empirical evaporation equations for Swan Coastal Plain wetlands.
Groundwater levels in the western suburbs of Perth have declined over 40 years and a disproportionate larger decline now seriously threatens Perry Lakes. Modelling suggests regional groundwater extraction exceeds recharge. Wetland managers can no longer maintain East Lake via local groundwater extraction. Artificial recharge using imported surface and waste water are possible future management options.
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Huss, Matthias. "Past and future changes in glacier mass balance /." Zürich : ETH, 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000256345.
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Wiklund, Sara. "Long-term glacier mass balance of Nordenskiöldbreen, Svalbard." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295789.
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The global warming that’s taking place have an impact over the Earth and the glaciers on Svalbard are undergoing rapid changes as a result. The annual air temperature has been rising on Svalbard since the early 1900’s and in a climate projection expected temperatures continue to rise. The glacial mass balance is important for monitoring glacier response to climate change. In this study the mass balance of Nordenskiöldbreen from 1957 to 2016 is modelled with a temperature-index model. The meteorological data used in the model, precipitation and air temperature, has been measured at a weather station located in Longyearbyen since 1957. The long simulation run makes trends in mass balance, precipitation and air temperature apparent. The mass balance can also be correlated to the temperature and precipitation, which provide important information on how these affect the behavior of glaciers. The results obtained can be used to predict how glaciers change in the future with climate change. In the simulation Nordenskiöldbreen’s mass balance has a negative trend, precipitation doesn’t have any trend and air temperature has a positive trend. The long-term mass balance is controlled by air temperature and the short-term interannual mass balance is caused by precipitation fluctuations.Den globala uppvärmningen som sker just nu har en påverkan över hela jorden och glaciärer på Svalbard genomgår snabba förändringar som följd. På Svalbard har den årliga medeltemperaturen stigit sedan början av 1900-talet och i en klimatprojicering förväntas temperaturen att fortsätta stiga. Den glaciala massbalansen är viktig för att övervaka glaciärers respons till klimatförändringar. I detta arbete modelleras Nordenskiöldbreens massbalans från 1957 till 2016 med hjälp av en temperaturindex modell. Den meteorologiska data som används i modellen, nederbörd och temperatur, har mätts vid en väderstation i Longyearbyen sedan 1957. Med den långa tidsperioden i modellen blir långsiktiga trender i massbalans, nederbörd och temperatur tydliga. Massbalansen kan även korreleras mot temperatur och nederbörd, vilket ger viktig information om hur dessa påverkar glaciärers beteenden. De resultat som framkommer kan användas för att förutspå hur glaciärer förändras i framtiden med en klimatändring. I simuleringen har Nordenskiöldbreens massbalans en negativ trend, nederbörd har ingen trend och temperatur har en positiv trend. Det är temperatur som styr den långsiktiga massbalansen och den kortsiktiga mellanårs-massbalansen styrs av nederbörds fluktuationer.
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Lauvdal, Anders. "Mass balance model for Hammerfest LNG plant Snøhvit." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-23363.
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The goal of the task is to develop and test a mass balance model for the entire Snøhvit facility which makes it possible to balance all streams inn and out. The model is implemented in an excel sheet. Also production rate calculations for LNG, LPG and condensate are made based on updated well and field data.
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Schwartz, Vegar. "Greenland ice mass balance using GRACE gravity data." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-24543.
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The mass balance of Greenland has been assessed with data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. Monthly data has been used through the time span of the study; January 2003 - December 2012. Level 2 data from three providers has been used. These are the Jet Propulsion Laboratory (JPL) , GeoForschungsZentrum (GFZ) and the Center for Space Research (CSR). The linear trend in this study points to -181±11 Gt/yr, -172±10 Gt/yr and -183±11 Gt/yr for the three data providers respectively. Notable corrections applied to improve the accuracy of this study are gravity leakage correction, adjustment for post-glacial rebound and non-isotropic smoothing filtering.This master thesis also gives an insight some of the mathematical background of physical geodesy and how this can be applied to use GRACE data to track changes in the gravity field. The methodology of applying this theory is explained in-depth with explanations of some natural assumptions along the way. Results are presented from correction calculations, important secular trend graphs and different time series plots of data from the three data providers. These results are compared to the works of other mentionable authors in the field of polar mass redistribution. Lastly, the thesis enlists some noteworthy strengths and weaknesses of the conducted study. To the author's knowledge, this is the first ice mass loss estimation of Greenland using GRACE level 2 Release 05 data decorrelated by non-isotropic filtering.
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Depoorter, Mathieu A. "Mass balance investigation of Antarctica from budget methods." Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702166.
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During the last 20 years, West Antarctica has experienced enhanced ice discharge to the ocean due to loss of buttressing from melting and collapsing ice shelves. On the other hand, increases in precipitation have been reported in East Antarctica in line with an expected wetter atmosphere in a warming climate. The big questions that still lie ahead are therefore: (i) Will the enhanced precipitations in East Antarctica compensate the dynamic mass losses observed in West Antarctica in the future? (ii) And what will be the resulting contribution to sea level rise (SLR)? To answer those questions we need to have a firm grip on the present day mass balance (MB) of Antarctica and on the mechanisms that govern both the surface mass balance (SMB) and the ice discharge (D) into the ocean. This thesis investigates the MB of Antarctica using the input-output method (10M) allowing for a direct diagnoses of local, regional and global MB in Antarctica. It does this for both the Antarctic Ice Sheet (AIS) and the ice shelves. Because the mass imbalance of AIS is of the order of 5-10% of both accumulation and attrition terms of the mass budget (~2000 Gt yr-1), all glaciers around Antarctica as well as each assumption made require precise attention. This thesis starts with a chapter exploring the grounding zone (Chapter 2), and then goes on to the actual mass balance calculations of the AIS in Chapter 3 and of the Antarctica ice shelves in Chapter 4. The Grounding lines (GL) of Antarctica have been widely studied using various techniques at a local and regional scale. In recent years GL datasets aiming for circumpolar coverage have been published using different approaches. However these datasets still bear unexplained discrepancies of up to tens of kilometres in numerous places around Antarctica. In Chapter 2 four recent datasets are compared which track either the surface break of slope (h) or the inward limit of tidal flexure (F) as proxies for the grounding point (G). From visual examination and from a particle tracking scheme (PTS), it is found that all GL datasets agree within 1-2 km on slow moving ice and on the sides of fast flowing features (FFFs). However it is confirmed that h, obtained from photogrametry or photo clinometry, is not a reliable proxy in central parts of FFFs because of multiple breaks-in-slope and artefacts. It is further confirmed that the most reliable methods to map G in such places are those tracking F. In addition, a gravitational driving stress (td) is computed from a 1 km Antarctic digital model elevation (DEM) and leads to the finding that driving stress mapping (DSM) supports dynamic approaches in grounding line location. This reconciles static and dynamic grounding line methods by showing that they map the same features providing that altimetry is used rather than imagery for static methods. Guided by these analyses a new, up-to-date, and complete grounding line of Antarctica is compiled. The potential of DSM is successfully tested on a grounding line migration case study in West Antarctica. To investigate the grounding zone around Antarctica and its ice dynamics, DSM is further used. DSM allows to map sharp transitions across G for slow moving ice, as well as complicated transitions on fast flowing features (FFFs). Complicated transitions on FFFs contradict the idea of there being an ideal transition occurring at G, whereby the ice flow regime switches from basal drag-dominated to lateral drag-dominated. Rather, it is found that acceleration occurs upstream of G and that deceleration occurs downstream of G. This changes the understanding of the grounding zone ice dynamics, where ice was believed to accelerate at G due to loss of basal drag. Using DSM in combination with ice penetrating radar (lPR), reported and new ice plains (i .e. lightly grounded areas) are detected and mapped. They extents cover ~55,000 km2 around the Ross, the Filchner-Ronne, and the Larsen C ice shelves. These findings have implications for our understanding of ice sheet stability since ice plains are particularly prone to grounding line migration and can stretch up to ~300 km inland of G. In Chapter 3 the MB of the AIS is assessed using the input-output method (lOM). The grounding line fluxes (GLF) and 5MB are estimated for 110 drainage basins covering the whole AIS. The GLF is computed using up to date grounding lines and additional radar ice thicknesses data compared to previous 10M studies. 5MB values are re-evaluated in light of new drainage basins defined from an ice velocity field rather than from topography. 5MB is taken as the 30 years mean of three regional climate models. Due to a number of improvements in the GLF methodology, an unprecedented 94% of the ice sheet area is surveyed, i.e. an increase of + 13% from the latest 10M study. Un-surveyed areas are accounted for using mass trends (MT) from a Bayesian hierarchical modelling solution from the RATES (Resolving Antarctic ice mass TrEndS) project. The integrated AIS mass balance is -63 ± 83 Gt yr- I and divides into -22 ± 28, -62 ± 45, and 22 ± 64 Gt yr- I for the Antarctic Peninsula (AP), the West Antarctic Ice Sheet (WAIS), and the East Antarctic Ice Sheet (EAIS), respectively. The integrated MB is therefore a lower 10M estimate compared to previous 10M studies and reconciles the 10M with the other MB methods of satellite gravimetry and altimetry. Because the stability of the AIS is intimately linked to the stability of ice shelves, Chapter 4 finally focuses on the mass balance of ice shelves around Antarctica, giving the partition between calving fluxes (CF) and basal mass balance (BMB), the main processes by which Antarctic ice is lost. Before this study, iceberg calving had been assumed the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 Gt yr- I . More recently, the importance of melting by the ocean had been demonstrated close to the grounding line and near the calving front. So far, however, no study had reliably quantified the calving flux and the BMB (the balance between accretion and ablation at the ice-shelf base) for the whole of Antarctica. The distribution of fresh water in the Southern Ocean and its partitioning between the liquid and solid phases was therefore poorly constrained. Here, a first estimate of the mass balance components for all ice shelves in Antarctica is produced using calving flux and grounding-line flux from satellite and airborne observations, modelled ice-shelf snow accumulation rates, and a regional scaling that accounts for un-surveyed areas. The total CF is 1321 ± 144 Gt yr- I and the total BMB is -1454 ± 174 Gt yr-1 . These numbers mean that about half of the ice-sheet surface mass gain is lost through oceanic erosion before reaching the ice front, and that the calving flux is about 34% less than previous estimates derived from iceberg tracking. In addition, the fraction of mass loss due to basal processes varies from about 10 to 90 % between ice shelves. A significant positive correlation between BMB and surface elevation change is found for ice shelves experiencing surface lowering and enhanced discharge. It is therefore suggested that basal mass loss is a valuable metric for predicting future ice-shelf vulnerability to oceanic forcing.
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Huss, Matthias Boes Robert. "Past and future changes in glacier mass balance /." Zürich : Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie, ETH Zürich, 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000263371.
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Greenfield, David W. J. "A local authority waste management mass balance model." Thesis, University of Brighton, 2010. https://research.brighton.ac.uk/en/studentTheses/2f7bca16-407c-44d0-a102-d03e3875e542.
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The pressure at the turn of the 21st century for Waste Disposal Authorities to change their waste disposal systems was both urgent and comprehensive, with emphasis being placed on moving towards the 3Rs; Reducing, Recycling and Recovering value from Municipal Wastes. This thesis explores how a mass balance model was created for the Brighton & Hove City and East Sussex County council Private Finance Initiative (PFI) contract, in response to the pressures for change and need for investment up to 2002. An identification and evaluation of the drivers for change at the time has been undertaken; with it being demonstrated that legislation, lack of landfill space and underlying public pressure were the stimulus for change.
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Peano, Daniele <1987>. "Simulation of Greenland mass balance evolution until 2100." Doctoral thesis, Università Ca' Foscari Venezia, 2015. http://hdl.handle.net/10579/8334.
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The evolution of the Greenland ice sheet mass balance has a potential impact on the regional and global climate. Moreover, the runoff from the Greenland ice sheet into the nearby ocean and its evolution are not well known, despite their potential impacts on ocean circulation. For this reason, this study investigates the evolution of Greenland mass balance and runoff during the 20th and 21st century by means of two thermo-mechanical ice sheet-ice shelves models. Transient simulations forced with the climate
simulated from seven CMIP5 models, are performed, and the evolution of surface mass balance and runoff for the entire ice-sheet and for seven drainage basins are analyzed.
The ability of one of the two thermo-mechanical ice sheet-ice shelves models in simulating basal melting and calving is investigated, in order to close the Greenland ice sheet mass balance. The simulated surface mass balance exhibits values in a wide range in the 20th
century (362 Gt/yr to -131 Gt/yr). The simulated surface mass balance decreases in time reaching values ranging from 59 Gt/yr to -436 Gt/yr for the RCP 4.5 simulations, and from -591 Gt/yr to -1857 Gt/yr for the RCP 8.5 simulations by 2100. This decrease is
characterized by an acceleration after the 2030s, more evident for the RCP 8.5 scenario, and the strongest reductions are simulated in the northern regions under both scenarios.
The simulated present-day (1980–1999) runoff ranges from 0.78 mm SLE/yr to 0.86 mm SLE/yr, and at the end of the 21st century (2081–2100) the runoff is projected to increase to 1.25 mm SLE/yr to 1.51 mm SLE/yr (2.36 mm SLE/yr to 2.94mm SLE/yr) under a RCP 4.5 (RCP 8.5) scenario. On regional scale, the highest amount of runoff is found in the northern and western basins, and the north-western one presents the largest values at the end of the 21st century, up to 0.68 mm SLE/yr under
a RCP 8.5 scenario. Finally, the simulated basal melting produced by one of the two thermo-mechanical ice sheet-ice shelves models exhibits small values compared to the surface meltwater values. Consequently, the basal melting can be neglected in the mass balance computation. The calving, in Greenland, occurs in small embayments along the Greenland margins, which are not properly reproduced in the ice sheet model due to the too low resolution. Consequently, calving has not been accounted for in mass balance
calculation due to the technical limitations of the ice sheet models used in this study.
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Akhand, Victoria. "Mass Balance Model of Impurities for the WoodRoll Process." Thesis, KTH, Skolan för kemivetenskap (CHE), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-215931.
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The depletion time for fossil fuels calculated from 2009 is 35 years for oil, 37 years for gas and 107 years for coal. Hence, it has become essential to reduce the dependence on fossil fuels by switching over to renewable resources. This in turn will also help in combating the negative effects on the environment like global warming. Thermochemical processes such as pyrolysis and gasification of biomass are considered the most efficient technology for converting biomass to useful energy carriers. Cortus Energy AB is a Swedish company that has developed a patented gasification technology called WoodRoll ® for gasification of fuels derived from biomass. However, ash in a thermochemical conversion process can cause corrosion, sintering, slag and poisoning of catalysts, which leads to operational problems. In addition, heavy metals such as Zn, Pb and Cd are environmentally problematic. These metals contribute to environmental pollution by contaminating the soil, which in turn can harm humans and the ecosystem via the food chain. The undesired elements should therefore be identified to minimize their impact on the overall thermochemical process and to reduce the emission of these harmful substances. The objective of this master thesis project, on behalf of Cortus Energy AB, was to investigate possible key numbers that can be used to describe and predict how the ash behaves in their patented WoodRoll® process. The key numbers that have been identified are empirically developed based on experience of coal combustion. These key numbers are regularly used for fuel derived from biomass by companies specializing in analyzing, although knowledge about whether they can actually be used on biomass is limited. In order to ensure that the use of these for biomass is correct, they must be experimentally verified in the future. In addition, a theoretical investigation is conducted to study which species can form and in what phase this occurs. The investigation reveals that there are no clear trends for how the inorganic elements behave since contradicting results from different studies have been reported. Formation of species and their phase depends on several parameters such as temperature, heating rate, particle size, volatility, quantity and interaction between the elements in the biomass. The thesis project ends with a mass balance model on selected inorganic elements for wood residues, as well as for bark. The model could be a tool for Cortus Energy AB to identify approximately how much of each element is present in each stream in the WoodRoll® process. The models are verified with analysis results. Inorganic elements that affect the overall process and its equipment have been selected for modelling. The volume percent of H2, CO, CO2 and CH4 in the models agree well with the values obtained by Cortus Energy AB. This shows that the thermodynamic equilibrium calculations performed are reasonable.De fossila bränslena beräknas vara förbrukade om 35 år för olja, 37 år för gas och 107 år för kol, räknat från år 2009. Användningen av fossila bränslen måste därför minskas genom övergång till förnybara resurser. Detta kommer i sin tur bidra till att motverka de fossila bränslenas negativa effekter på miljön, såsom den globala uppvärmningen. Termokemiska processer, som pyrolys och förgasning av biomassa, anses vara den mest effektiva tekniken för att omvandla biomassa till användbara energibärare. Cortus Energy AB är ett svenskt företag som har utvecklat en patenterad förgasningsteknik kallad WoodRoll ® för förgasning av biomassa. Aska i en termokemisk omvandlingsprocess kan ge upphov till korrosion, sintring, slagg samt förgiftning av katalysatorer vilket leder till operativa problem. Dessutom är tungmetaller såsom Zn, Pb och Cd miljömässigt relevanta. Dessa metaller bidrar till förorening av miljön, vilket i sin tur kan skada människor och ekosystemet via näringskedjan. De oönskade elementen bör därför identifieras för att minimera deras inverkan på den övergripande termokemiska processen och för att reducera utsläppet av dessa ämnen. Syftet med detta examensarbete, på uppdrag av Cortus Energy AB, var att undersöka möjliga nyckeltal som kan användas för att beskriva och förutse hur askan beter sig i deras patenterade WoodRoll® process. De nyckeltal som har undersökts teoretiskt är empiriskt utvecklade utifrån erfarenhet av förbränning av kol. Dessa nyckeltal används regelbundet av analysföretag på bränslen från biomassa trots att kunskapen om huruvida dessa faktiskt kan användas på biomassa är begränsad. För att säkerställa att användningen av dessa nyckeltal för aska från biomassa är korrekt måste de verifieras experimentellt i framtiden. Vidare görs en teoretisk undersökning för att studera vilka föreningar som möjligen kan bildas och i vilken fas detta sker. Denna undersökning visar att det inte finns en tydlig trend för hur de oorganiska elementen beter sig då olika studier har rapporterat motstridiga resultat. Vilka föreningar som bildas och i vilken fas i processen det i så fall sker beror på flera parametrar såsom temperatur, hastighet av uppvärmning, partikelstorlek, volatilitet, mängd samt interaktionen mellan de element som finns i biomassan. Arbetet avslutas med en massbalansmodell på utvalda oorganiska element för grenar och toppar, förkortat GROT, samt för bark. Detta kan bli ett verktyg för Cortus Energy AB för att identifiera ungefär hur mycket av varje element som finns i varje flöde WoodRoll®-processen. Modellen verifieras med analysresultat. Oorganiska element som påverkar processen och dess utrustning har valts för denna modell. Volymprocenten för H2, CO, CO2 and CH4 i modellen stämmer väl överens med de värden som Cortus Energy AB har erhållit. Detta visar att de termodynamiska jämviktsberäkningar är rimliga.
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Rainville, Simon 1974. "A two-ion balance for high precision mass spectrometry." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/16934.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2003.Includes bibliographical references (leaves 121-124).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
This thesis describes the demonstration of a new technique that allows masses to be compared with fractional uncertainty at or below 1 x 10-11, an order of magnitude improvement over our previous results. By confining two different ions in a Penning trap we can now simultaneously measure the ratio of their two cyclotron frequencies, making our mass comparisons insensitive to many sources of fluctuations (e.g. of the magnetic field). To minimize the systematic error associated with the Coulomb interaction between the two ions, we keep them about 1 mm apart from each other, on a common magnetron orbit. We have developed novel techniques to measure and control all three normal modes of motion of each ion, including the two strongly coupled magnetron modes. With the help of a new computer control system we have characterized the electric field anharmonicities and magnetic field inhomogeneities to an unprecedented level of precision. This allows us to optimize the trap so that our measurement of the cyclotron frequency ratio is to first order insensitive to the field imperfections. Using the ions 13C2H2+ and 14N2+, we performed many tests of our understanding of the ions dynamics and of the various sources of errors in this technique. From these we conclude that there should be no systematic error in our measurements at the level of 5 x 10-12. Thus we feel confident reporting a value for the mass ratio of these ions with an uncertainty of 10-11.
(cont.) In this thesis, we also report measurements of the two mass ratios m[33S+]/m[32SH+] and m[29Si+]/m[28SiH+] with a relative uncertainty of less than 10-1l, which makes them the best known mass ratios to date. These can be combined with precise measurements of high-energy gamma-rays to provide a direct test of the relation E = mc2. This is a test of special relativity which does not rely on the assumption of a preferred reference frame. The uncertainty on the atomic mass of 29Si is also reduced by about an order of magnitude.
by Simon Rainville.
Ph.D.
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da, Silva Cerozi Brunno, and Silva Cerozi Brunno da. "Phosphorus Dynamics, Mass Balance and Mineralization in Aquaponics Systems." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/620832.
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This study involves tracing inputs, partitioning, and outputs of phosphorus (P) through an aquaponics system. A mathematical model was developed to describe the dynamics of phosphorus in an aquaponics nutrient solution, and to maximize P use efficiency and minimize P waste. We assessed the influence of pH on the availability and speciation of phosphorus in an aquaponics nutrient solution. By using Visual MINTEQ, a freeware chemical equilibrium model for the calculation of element speciation, solubility equilibria, and sorption for natural waters, it was discovered that high pH values favor the formation of calcium phosphate complexes, decreasing the concentration of free phosphorus in aquaponics nutrient solutions. In addition, the mineralization of organic phosphorus in aquaponics systems was evaluated using treatments with phytase supplementation to fish diets, and incorporation of a microbial inoculant in the aquaponics nutrient solution. Overall, dietary phytase and microorganisms promoted phosphorus mineralization and enhanced phosphorus utilization in aquaponics systems. In the end, we conclude that aquaponics systems can keep the same growth performance and quality of vegetable crops grown in conventional systems when the availability and dynamics of phosphorus are well managed.
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Filipovic, Marko. "Mass balance of perfluoroalkyl acids in the Baltic Sea." Licentiate thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-88779.
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Perfluoroalkyl acids (PFAAs) are man-made chemicals. Their unique properties make them beneficial for a wide range of industrial and consumer applications, such as constituents in fire fighting foams, hydraulic oils and food packaging materials.PFAAs have shown to be highly persistent in the environment, and the toxicological potential of long chain PFAA homologues is of a concern. International regulation and voluntary actions by the industry have been implemented and led to reduced primary emissions of PFAAs to the environment. However, the concentrations of some PFAAs in e.g. birds from the Baltic Sea are still very high and of ecotoxicological concern. Measures to reduce the PFAA contamination require an understanding of the sources and how the PFAAs are being transported in the environment.In this licentiate thesis a mass balance was assembled for perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), perfluorodecanoic acid (PFDA) and perfluorooctane sulfonic acid (PFOS) in the Baltic Sea. A one-box model was used including the input pathways river inflow, atmospheric deposition, wastewater discharges and inflow from the North Sea via the Danish Straits, while the loss processes considered were sediment burial, transformation of the chemicals and outflow to the North Sea via the Danish Straits. Additionally, the inventories of the four target PFAAs in the Baltic Sea were estimated. Both chemical fluxes and inventories were estimated using recently published monitoring data (2005-2010).In order to obtain a detailed perspective on the current knowledge regarding PFAAs in the Baltic Sea, challenges and uncertainties in data selection were discussed for the most dominant input pathways. This included WWTP emissions and calculation of emission factors (EFs), atmospheric deposition and riverine inflow.River inflow and atmospheric deposition were the dominant inputs, while wastewater treatment plant (WWTP) effluents made a minor contribution. The input to the Baltic Sea exceeded the output for all 4 PFAAs, suggesting that inputs were higher during 2005-2010 than during the previous 20 years despite efforts to reduce emissions of PFAAs. Comparing the difference between PFAA input and output with the PFAA inventory, the doubling time for the concentration in the Baltic Sea was estimated to be 8-94 yr for PFHxA, 12-16 yr for PFOA, 3-5 yr for PFDA and 4 yr for PFOS. The surplus of the input can be an effect of retention and delayed release of PFAAs from atmospheric deposition in the soils and groundwater of the watershed.The licentiate thesis contributes to a holistic understanding of the major input and output pathways and inventories of PFAAs in the Baltic Sea. Furthermore, it points out current knowledge gaps in our understanding of sources and fate of PFAAs in the aquatic environment.At the time of the defence the following papers were unpublished and had a status as follows: Paper 1: Manuscript
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Arendt, Anthony Alan. "Approaches to modelling the mass balance of High Arctic glaciers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22565.pdf.
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Spikes, Vandy Blue. "A Mass Balance Study of the West Antarctic Ice Sheet." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/SpikesVB2003.pdf.
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Vernon, Christopher L. "Surface mass balance model intercomparison for the Greenland ice sheet." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633454.
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our simulations of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) are compared over the period 1960-2008. Three use a regional climate model to downscale ECMWF reanalysis (ERA-40) and operational analysis data, while the fourth uses the same inputs but an empirical downscaling approach and melt model. These reconstructions have been used in a variety of applications but prior to this study little was known about their consistency with each other and the impact of the downscaling method on the result. The reconstructions are compared to assess the consistency in regional, seasonal and integrated 5MB components and evaluated against a suite of observational data. Three key areas of difference between the models have been identified. Firstly differences in how the ERA-40 reanalysis data are downscaled by the models. Secondly differences in how the 5MB components are calculated. And thirdly differences in the domain, the ice sheet mask used. Total 5MB estimates for the GrIS are in agreement within 34% of the four-model average when a common ice sheet mask is used. When models' native land/ice/sea masks are used this spread increases to 57%. The components of 5MB, with the exception of refreeze, show a similar level of agreement once a common mask is used. Previously noted differences in the models I estimates are partially explained by ice sheet mask differences. Agreement is higher (18% spread) in the accumulation area than the ablation area (38% spread) suggesting relatively high uncertainty in the estimation of ablation processes. Regionally there is less agreement, suggesting spatially compensating errors improve the integrated estimates. Modelled 5MB estimates are compared with in situ observations, gravimetric observations from GRACE and altimetry observations from ICESat. Through the use of a surface density and firn compaction model individual components of 5MB are, indirectly, able to be evaluated against altimetry observation.
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Ranasinghe, Milinda A. "Modelling the mass and energy balance in a compost biofilter." Thesis, University of Canterbury. Chemical and Process Engineering, 2003. http://hdl.handle.net/10092/7492.
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A biofilter model was developed using the mass and energy balances in the gas, liquid and solid phases, which related the biofilter performance to the water content in the packing material. A key simplification of the model was that the concentration gradients in the biofilm were neglected by treating the biofilm/water layer as well mixed and in instantaneous equilibrium with the gas phase. Thus, the biofilm geometry and density parameters were lumped into the overall degradation term. The solid phase was treated as a separate well-mixed layer but solid phase dynamics were accounted for by using the Linear Driving Force (LDF) mass transfer model. The mixed form of Richard's equation together with experimentally obtained unsaturated hydraulic conductivity and water retention curves for compost were used in the continuity equation for the liquid water phase. This approach produced a model where all parameters could be potentially independently determined.
The model was used to test suitable irrigation strategies for a biofilter system degrading toluene subject to different operational conditions. Under this approach both unidirectional and directionally switched biofilter configurations were tested for a 1 m long column. The unidirectional schemes incorporated both open and closed loop irrigation schemes, where the latter was based on commonly used on-line moisture measurement techniques. All schemes were evaluated based on the removal efficiency achieved and the leachate produced. Simulations under a constant irrigation rate of 5.46x 10⁻²g/m²s for a mass loading range of 13-60 g/m³h yielded removals ranging from 88%-26%. An order of magnitude drop in leachate under the high loading indicated severe drying in the system. For a high mass loading of 60 g/m³h, directional switching with a one-day frequency yielded a removal of 33% Vs 26% in an up flow scheme with similar leachate rates. Feedback control on water content provided an improved removal of 84% as compared to 73% under constant irrigation, when both schemes were subjected to load and inlet air step disturbances from 13 g/m³h to 62 g/m³h and from 298 K to 283 K respectively. A sensitivity analysis indicated that the model was most sensitive to the relationship between moisture content and degradation, which was also reflected by the high sensitivity of the model to the kinetic parameters in the degradation term.
A novel batch recycle reactor was thus developed to investigate the effect of water content changes on the degradation rate in low water content systems such as biofilters. The reactor tightly controlled the water content of the unsaturated packing material by using the principle of a suction cell. Experimental runs were performed with toluene as the contaminant using unamended compost at a constant temperature of 30°C. Matric potential in the compost was maintained at values between -6 and -36 cm H₂O and the gas phase was monitored by sampling/gas chromatography. A soil water retention curve relating matric potential to gravimetric water content was generated for the compost. Periodic dry weight analyses of reactor samples together with the water retention curve verified moisture content control. Degradation results demonstrated a biologically limited region followed by a non-linear region at lower concentrations. Elimination capacities were obtained along the wetting and drying curves and changes in the water content affected the removal rates in the linear region ranging from 155 g/m³h to 24 g/m³h over the matric potential range investigated. Repeatability studies indicated that moisture content was the most likely parameter that influenced the changes in performance. Batch scale experiments were also performed using microbially inhibited compost, which provided linear sorption isotherms for toluene on compost at concentrations between 0-1000 ppmv and temperature values of 25°C and 35°C.
The simulation model developed here provides a useful tool to implement and evaluate various operational schemes under different irrigation strategies. This is achieved by way of greater flexibility in incorporating the various schemes into the base model and the comparatively low simulation time to obtain the relevant results.
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Kunzen, Thomas. "HYDROLOGIC MASS BALANCE OF PERVIOUS CONCRETE PAVEMENT WITH SANDY SOILS." Master's thesis, University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3249.
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Use of pervious concrete pavement as a method of stormwater management has shown great promise in previous studies. Reduction in runoff, water quality improvements, and long-term economic benefits are but a few of its many advantages. Regulatory agencies such as the St. Johns River Water Management District require further research into the performance of pervious concrete pavement before granting credits for its use as a best management practice in controlling stormwater. As a part of a larger series of studies by UCF's Stormwater Management Academy, this thesis studies the hydrologic mass balance of pervious concrete pavement in sandy soil common in Florida. In order to conduct this study, a field experiment was constructed at the UCF Stormwater Field Lab. The experiment consisted of three 4-foot tall cylindrical polyethylene tanks with 30-inch diameters. All three tanks were placed into the side of a small embankment and fitted with outlet piping and piezometers. The test tanks were assembled by laying a 6-inch layer of gravel into the bottom of each tank, followed by a layer of Mirafi geofabric, followed by several feet of fine sand into which soil moisture probes were laid at varying depths. Two of the tanks were surfaced with 6-inch layers of portland cement pervious concrete, while the third tank was left with a bare sand surface. Mass balance was calculated by measuring moisture influx and storage in the soil mass. Data collection was divided into three phases. The first phase ran from August to November 2005. Moisture input consisted of normal outdoor rainfall that was measured by a nearby rain gauge, and storage was calculated by dividing the soil mass into zones governed by soil moisture probes. The second phase ran for two weeks in March 2006. Moisture input consisted of water manually poured onto the top of each tank in controlled volumes, and storage was calculated by using probe readings to create regression trendlines for soil moisture profiles. The third phase followed the procedure identical to the second phase and was conducted in the middle of April 2006. Data tabulation in this study faced several challenges, such as nonfunctional periods of time or complete malfunction of essential measuring equipment, flaws in the method of calculating storage in phase one of the experiment, and want of more data points to construct regression trendlines for soil moisture calculation in phases two and three of the experiment. However, the data in all phases of the experiment show that evaporation volume of the tanks with pervious concrete surfacing was nearly twice that of the tank with no concrete. Subsequent infiltration experiments showed that pervious concrete pavement is capable of retaining a portion of precipitation volume, reducing infiltration into the underlying soil and increasing total evaporation in the system.M.S.C.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
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Wong, T.-Y. "Mass balance of heavy metal pollution in a river catchment." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382893.
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VERA, YSRAEL MARRERO. "PREDICTING MERCURY CONCENTRATION IN TUCUNARÉ USING MASS BALANCE AND BIOENERGETICS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6133@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO mercúrio usado no garimpo do ouro na região amazônica é liberado para a atmosfera, solo e rios. Uma vez na atmosfera, o metal é oxidado e imediatamente se deposita. Na água, ocorre a transformação para o metilmercúrio principalmente pela ação de microrganismos. A formação do metilmercúrio aumenta a dispersão e biodisponibilidade do elemento no ambiente aquático. O metilmercúrio pode ser incorporado pelo plancton entrando, assim, na cadeia alimentar. A concentração do metal aumenta a medida que se ascende nos níveis tróficos da cadeia, atingindo os valores mais elevados em peixes carnívoros como o tucunaré. Dessa forma, as emissões de mercúrio provocam a contaminação dos recursos naturais e aumentam os riscos para a saúde dos consumidores habituais de pescado. O objetivo deste trabalho é testar um modelo de bioacumulação de mercúrio em peixes para estimar concentrações em predadores de topo da cadeia alimentar. O modelo pode ser usado como ferramenta para a gestão ambiental de ecossistemas aquáticos potencialmente contaminados com mercúrio. Este objetivo foi atingido através da combinação dos modelos de balanço de massa de Trudel e bioenergético de Wisconsin, aplicados em espécies tropicais do gênero Cichla (tucunaré) da bacia do rio Tapajós. O modelo bioenergético de Wisconsin foi usado para determinar as taxas de consumo de alimento a partir de dados de crescimento estimados. Os parâmetros usados nos modelos foram obtidos na literatura. A habilidade da modelagem na predição dos teores de mercúrio em tucunarés foi avaliada através da comparação com dados de campo obtidos nos anos 1992 e 2001, no rio Tapajós e no sistema de lagos Maicá. Os melhores resultados foram alcançados para os espécimes coletados no ano 1992, o que parece estar relacionado com uma melhor estimativa da concentração de mercúrio no alimento neste ano.
The mercury used in the artisanal mining (garimpo) of gold in the Amazon region is emitted to the atmosphere, soil and rivers. Once in the atmosphere, the metal is oxidized and immediately deposited. In the water, the transformation to methylmercury takes place mostly due to the action of microorganisms. The formation of methylmercury increases the dispersion and bioavailability of the element in the aquatic environment. The methylmercury can be assimilated by the plankton and enters the food chain. The concentration of the metal increases further up in the trophic levels of the chain and reaches the highest values in carnivorous fishes like tucunaré. Thus, the mercury emissions cause the contamination of natural resources and enhance the risks to the health of regular fish consumers. The objective of this work is to test a model for bioaccumulation of mercury in fishes. The model calculates concentrations in top predators of the food chain and can be used as a tool for the management of aquatic ecosystems potentially contaminated with mercury. This objective was accomplished through the combination of the Trudel mass balance and Wisconsin bioenergetics models, applied to tropical species of the Cichla (tucunaré) genre of the Tapajós river basin. The Wisconsin bioenergetics model was utilized to determine the rates of food consumption from estimated fish growth data. The parameters used in the models were found in the literature. The ability of the models to predict mercury contents in tucunarés was evaluated by comparison with the field data, obtained in 1992 and 2001, in the Tapajós River and in the Maicá lakes. The best results were attain ed for specimens collected in 1992 what seems to be related to a better estimate of mercury concentration in the food in this year.
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BARRETO, GISELE DE OLIVEIRA. "MASS BALANCE DATA RECONCILIATION OF THE URUCU- MANAUS GAS PIPELINE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2015. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=26316@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Se por um lado à privatização do setor de energia, que induz acirrada concorrência, tem estimulado a inovação tecnológica e a adoção de mecanismos de incentivos à eficiência operacional, a regulação do mercado introduz mecanismos de controle requerendo maior responsabilidade no uso consciente da energia de sorte a assegurar a eficiência energética e a proteção ambiental. Pressões de organizações ambientalistas internacionais e a crescente demanda por energia explicam a tendência mundial pelo uso de combustíveis fósseis mais limpos. O baixo nível de emissões e resíduos associados ao processo de combustão de gás natural qualifica esta commodity energética como um elemento estratégico para integrar a matriz energética de organizações e países comprometidos com a sustentabilidade global. O impacto econômico associado à medição de gás natural exige uma otimização do controle do balanço de massa no sistema de entrega. A aplicação da Metodologia de Reconciliação de Dados constitui o objetivo deste trabalho. A técnica provou ser uma ferramenta eficaz para a avaliação do balanço de massa em um gasoduto durante o período de operação associado ao transporte de gás natural. A natureza intrínseca do seu algoritmo de cálculo, que leva em conta a redundância nas medições, qualifica a metodologia para aumentar a confiabilidade da medição assim reduzindo a incerteza individual associada a cada grandeza física capaz de interferir na medição e identificar erros grosseiros. Fundamentado na avaliação metrológica do balanço de massa de um gasoduto brasileiro, os resultados do estudo permitem discutir a adequação da técnica proposta de reconciliação de dados. Dentre as conclusões do trabalho, foi possível mostrar que o uso da técnica de tratamento dos dados do gás não contado (unaccounted for gas) pode atingir valores inferiores a 0,3 porcento, comparando-se, assim, à tolerância preconizada em nível internacional.
If on the one hand, privatization of the energy sector, which induces keen competition, has stimulated technological innovation and the adoption of incentive mechanisms for operational efficiency, regulation of the market introduces control mechanisms requiring greater responsibility in the conscious use of energy so as to ensure energy efficiency and environmental protection. Pressure from international environmental organizations and the growing demand for energy, explain the worldwide tendency for the use of cleaner fossil fuels. The lower levels of emissions and residues associated with the combustion process of natural gas classify this energy commodity as a strategic element to enter into the energy matrix of organizations and countries committed to global sustainability. The economic impact associated with the measurement of natural gas, demands optimization in controlling the mass balance in the delivery system. Application of the Data Reconciliation Methodology constitutes the objective of this work. The technique proved to be an efficient tool for the evaluation of the mass balance in a gas pipeline for the period of operation associated with the transport of natural gas. The intrinsic nature of its calculation algorithm, which takes into account the redundancy of measurements, qualifies the methodology to increase the confidence of measurement, thereby reducing the individual uncertainty associated with each physical volume capable of interfering with the measurement and identify gross errors. Based on the metrological evaluation of the mass balance of a Brazilian pipeline, the results of the study enable discussion on the adequacy of the data reconciliation technique proposed. Among the conclusions of the work, it was possible to demonstrate that the use of the technique in treating the data of unaccounted for gas, could achieve values lower than 0.3 percent, thereby comparable with the tolerances advocated at international level.
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Meister, R. "Estimating Antarctic ice sheet mass balance from gravimetry and altimetry." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1364858/.
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Estimates of the Antarctic ice sheet mass balance from the past ten years show great discrepancy. Deriving mass values from gravity measurements is a ffected by corrections for postglacial rebound (PGR). Calculating Antarctic ice sheet mass balance from altimetry satellites requires knowledge of surface densities. Here, two instruments were used in conjunction to constrain ice sheet mass balance. Surface height trends from the Envisat radar altimeter and mass trends from GRACE were analysed for the period January 2003 until October 2010. An analysis of errors related to GRACE gravity measurements was carried out and a best method for removal of errors was chosen. Envisat altimetry corrections were examined. Envisat surface height trends were converted into units of mass and smoothed with a 300km Gaussian filter in order to be compatible with the GRACE mass trend. This was done using a) the density of ice (917kg=m3), b) a firn density of 450kg=m3 and c) a variable surface density map of the Antarctic derived from observations of changes in the pattern of surface height trends. Subtracting the altimetry mass trend from the GRACE mass trend provides results dominated by the absence of altimetry data in the Antarctic peninsula and south of 81:6 degrees south. Therefore, ICESat altimetry trend values were added to the Envisat trend map, where available. The GRACE mass trend and the smoothed altimetry trend converted to mass show very good agreement. The diff erence between GRACE and the combined Envisat-ICESat altimetry trends can be interpreted as a combination of PGR and error. Integrating this di fference provides considerably smaller PGR values than all commonly used PGR models. The integrated area trends from both gravimetry and altimetry show mass loss for West Antarctica, mass gain for East Antarctica and an acceleration of melting in the Amundsen Sea Sector.
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Rivera, Andres. "Mass balance investigations at Glaciar Chico, Southern Patagonia Icefield, Chile." Thesis, University of Bristol, 2004. http://hdl.handle.net/1983/987b1d4c-49ea-4dab-b53d-a054a453faa6.
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The Southern Patagonia Icefield (SPI) is the largest temperate ice mass at mid-latitudes in the Southern Hemisphere, and an area where most glaciers have been retreating during the last 50 years. Based on field data, vertica aerial photographs and satellite images, the changes experienced by Glaciar Chico, are presented. These glacier variations are compared to climatic changes recorded in Patagonia during recent decades through modelling of the glacier mass balance, using a degree-day factor model forced with climatic and field data. The main aim of this work is to analyse the mass balance of Glaciar Chico, in order to distinguish climatically driven glacier behaviour from tha which could be related to ice dynamics. Between the end of the Little Ice Age and the middle of the 20`h century the glacier retreated at relatively low rates, but in recent decades there has been an acceleration in the rate of ice thinning and area loss of up to 0.33 ± 0.22 km2 a"1. In total, the volume lost due to frontal retreat and area change between 1975 and 2001 is -1.73 ± 1.43 km3 water equivalent (w. eq. ). Although the glacier was slowly thinning before 1975, during recent decades the rate of thinning has accelerated to reach a maximum of -5.4 ± 0.55 m a-1 at the glacier front. From GPS data, ice thinning was also observed at the lower elevations of the accumulation area, at an average rate of -1.9 ± 0.14 m a"' between 1998 and 2001. Interestingly, the thinning rate in the lower accumulation zone is three times higher than the mass balance estimated for that part of the glacier. Analysis of climatic data showed a warming trend of up to +0.033°C a-' between 1969 and 1990, and a trend of decreasing precipitation of up to -27 mm a"2 between 1961 and 1990. The mass balance model was run several times in order to obtain the best-fit parameters which were calibrated with direct observations of accumulation and ablation from glaciers across Patagonia. The resulting net mass balance for Glaciar Chico obtained from the model yielded an average of -0.165 ± 0.059 km3 a-' w. eq. between 1975 and 2001, but this only accounts for three quarters of the volume lost by the glacier due to ice elevation changes (-0.226 ± 0.081 km3 a"1 w. eq. ). It is therefore concluded that in addition to the response of Glaciar Chico to climatic changes, a dynamic component also affects its behaviour, which could possibly be related to enhanced sliding generated by an increase in melt water, and/or a long term change in the glacier and its neighbours in the SPI.
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Taylor, Astrea. "Phosphorus mass balance for hypertrophic Grand Lake St. Marys, Ohio." Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347933945.
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Okumura, Yutaka. "Mass Balance and Bioaccumulation of Major Dioxins in Sendai Bay." Kyoto University, 2011. http://hdl.handle.net/2433/135409.
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Fang, Yuan-Hao, Xingnan Zhang, Chiara Corbari, Marco Mancini, Guo-Yue Niu, and Wenzhi Zeng. "Improving the Xin'anjiang hydrological model based on mass–energy balance." COPERNICUS GESELLSCHAFT MBH, 2017. http://hdl.handle.net/10150/625180.
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Conceptual hydrological models are preferable for real-time flood forecasting, among which the Xin'anjiang (XAJ) model has been widely applied in humid and semi-humid regions of China. Although the relatively simple mass balance scheme ensures a good performance of runoff simulation during flood events, the model still has some defects. Previous studies have confirmed the importance of evapotranspiration (ET) and soil moisture content (SMC) in runoff simulation. In order to add more constraints to the original XAJ model, an energy balance scheme suitable for the XAJ model was developed and coupled with the original mass balance scheme of the XAJ model. The detailed parameterizations of the improved model, XAJ-EB, are presented in the first part of this paper. XAJ-EB employs various meteorological forcing and remote sensing data as input, simulating ET and runoff yield using a more physically based mass–energy balance scheme. In particular, the energy balance is solved by determining the representative equilibrium temperature (RET), which is comparable to land surface temperature (LST). The XAJ-EB was evaluated in the Lushui catchment situated in the middle reach of the Yangtze River basin for the period between 2004 and 2007. Validation using ground-measured runoff data proves that the XAJ-EB is capable of reproducing runoff comparable to the original XAJ model. Additionally, RET simulated by XAJ-EB agreed well with moderate resolution imaging spectroradiometer (MODIS)-retrieved LST, which further confirms that the model is able to simulate the mass–energy balance since LST reflects the interactions among various processes. The validation results prove that the XAJ-EB model has superior performance compared with the XAJ model and also extends its applicability.
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Luty, Mark. "Precision balances for measurement of mass and air density." Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363465.
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Fujita, Koji, and 耕史 藤田. "Effect of precipitation seasonality on climatic sensitivity of glacier mass balance." Elsevier, 2008. http://hdl.handle.net/2237/11360.
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DeBuhr, Christopher Leonard. "Metamorphic petrology and mass balance analysis in the Bugaboo contact aureole." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0019/NQ49488.pdf.
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DeBerardinis, Jeffrey T. Whalen Stephen Charles. "Nitrogen mass balance for spray fields fertilized with liquid swine waste." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2006. http://dc.lib.unc.edu/u?/etd,262.
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Thesis (M.S.)--University of North Carolina at Chapel Hill, 2006.Title from electronic title page (viewed Oct. 10, 2007). "... in partial fulfillment of the requirements for the degree of Masters of Science in the Department of Environmental Sciences and Engineering." Discipline: Environmental Sciences and Engineering; Department/School: Public Health.
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Petroni, Ricardo N. (Ricardo Nicolas) 1971, and Peter H. (Peter Hampus) 1973 Israelsson. "Mass balance and 3D model of PAHs in Boston's inner harbor." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50019.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (leaves 192-199).
by Ricardo N. Petroni, Peter H. Israelsson.
M.Eng.
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Burke, Megan Elizabeth. "Mass balance modeling of polychlorinated biphenyls in the Lower Duwamish Waterway." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/104192.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 30-31).
Remediation is most effective when a site is properly characterized. The Lower Duwamish Waterway (LDW) in Seattle, Washington is contaminated with polychlorinated biphenyls (PCBs). A zero dimensional mass balance of the 5 mile long waterway, which ends in Elliott Bay, helps to determine the different sources and concentrations of PCBs within the Lower Duwamish Waterway to aid future remedial activities. There are four unknown state variables: freshness, suspended sediment concentration, dissolved phase total PCB concentration, and sorbed phase total PCB concentration. The sole freshness source was the Green River and the freshness sink was the flushing at the downstream mouth. PCBs exist in sorbed and freely dissolved phases. Sorbed PCB sources include: the incoming Green River, laterals, and erosion. Sinks of sorbed PCBs include: deposition, flushing, and desorption. The Green River, laterals, diffusion, and desorption are all dissolved PCB sources, while the sinks are flushing and volatilization to the atmosphere. The calculated four state variables were compared to measured values and a sensitivity analysis was performed on the sources.
by Megan Elizabeth Burke.
M. Eng.
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Migliavacca, Alencar. "Balanço de massa, energia e exergia na produção intensiva de frangos de corte." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-06122017-090731/.
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A produção brasileira de frangos de corte evidenciou-se com o sistema de produção integrada, ao elevar a eficiência e a qualidade na conversão de proteína animal. Contudo, devido à rápida evolução tecnológica com crescente demanda energética e a diversificação dos sistemas de produção em diferentes microclimas, elucidar os processos de conversão de massa e energia tornou-se uma tarefa desafiadora neste sistema de produção. Constantemente, pesquisadores, produtores e agroindústria buscam processos mais rentáveis, reduzindo a demanda em mão de obra e o impacto ambiental. No entanto, nunca foi feita uma avaliação integrada do sistema produtivo de frangos de corte, considerando-se os aspectos quantitativos, energéticos e ambientais. Deste modo, o objetivo deste trabalho é promover um detalhado balanço de massa e energia, além de avaliar por meio da análise exergética, a qualidade das conversões de energia no processo produtivo de frangos de corte. Com o levantamento de insumos, produtos e rejeitos diretos, vinculados ao ciclo de produção, foram quantificadas as vazões mássicas para os diferentes processos do ciclo e, aplicando-se a avaliação exergética, obteve-se um diagnóstico completo da quantidade e qualidade energética envolvidas. Considerando o cenário adotado, em termos mássicos, as maiores demandas identificadas para os insumos foram a água (69,2%) e a ração (24,9%). Na saída do processo, os Gases de Efeito Estufa (GEE)/particulados extraídos através da ventilação (39,4%), os gases de combustão da lenha (25,6%) e a cama (14,2%) formam os principais rejeitos. A massa de frangos representa 20% das saídas. Foi identificado que a relação entre o consumo de água e ração é função da temperatura. Em termos energéticos, as maiores contribuições identificadas para os insumos foram a ração (77,7%) acompanhada do material absorvente (9,7%) e da lenha (9,6%). Na saída do processo lideram as energias associadas aos frangos (33,2%) e da cama gerada (32,1%). O rendimento energético obtido para galpões convencionais foi de 27%. Os processos que mais destroem exergia dentro do ciclo produtivo são a formação da cama de frangos a partir das excretas (51,5% em convencionais e 48,2% em climatizados) e a combustão da lenha para aquecimento (21,9% em convencionais e 20,5% em climatizados). Além disso, foi estimado o rendimento de Segunda Lei para o ciclo próximo de 26%. Foram introduzidos os índices energético e exergético de produção permitindo a comparação entre diferentes sistemas. Como principal resíduo, a cama de frangos gerada no ciclo, quando reutilizada como insumo para aquecimento do próprio aviário na forma de briquetes, pode elevar as eficiências. Comparando-se as demandas médias para as duas formas de aquecimento, foi constatado que o uso do GLP é mais favorável ao ambiente se comparado à lenha, devido à forma direta de transferência de calor aos frangos. É aconselhável, em dias quentes, elevar a velocidade do ar, utilizando o resfriamento evaporativo somente em casos de elevada temperatura ambiente, pois a introdução de água eleva a exergia dissipada no ciclo.Brazilian production of broilers has been highlighted with the implantation of the integrated production system, which improved the efficiency and quality in animal protein conversion. However, due to the rapid technological evolution with the increasing energy demand and the diversification of production systems in different microclimates, elucidating mass and energy conversion processes has become a challenging task regarding this production system. Constantly, researchers, producers and agribusiness look for more profitable processes, reducing the labour demand and environmental impact. However, an integrated evaluation of the productive system of broilers, considering the quantitative, energy and environmental aspects has never been carried out. Thus, this study aims at promoting a detailed mass and energy balance and to evaluate the quality of the energy conversions in the productive process of broilers by means of exergy analysis. With the survey of inputs, products and direct wastes, linked to the production cycle, the mass flow rates for the different processes of the cycle were quantified and a complete diagnosis of the quantity and quality energetic involved was obtained applying the exergy evaluation. Considering the scenario adopted, in mass terms, the greatest demands identified for the inputs were water (69.2%) and feed (24.9%). At the exit of the process, the greenhouse gases/dust extracted through ventilation (39.4%), the firewood combustion gases (25.6%) and the litter poultry generated (14.2%) are the main outputs. The broilers mass was quantified in 20%. The relation between water and feed consumption has shown to be the temperature. Regarding energy, the largest contribution identified for the inputs was feed (77.7%) followed by the absorbent (9.7%) and firewood (9.6%). At the exit of the process lead the energy associated with the broilers (33.2%) and the poultry litter generated (32.1%). The energy performance obtained for conventional shed was 27%. The processes of the largest exergy destroyed within the productive cycle are the litter poultry converted from excreta (51.5% in conventional and 48.2% in air conditioning) and the combustion of wood for heating (21.9% in conventional and 20.5% in air conditioning). In addition, the second law performance for the cycle was estimated in about 26%. The energy and exergy production index was introduced allowing for the comparison among different systems. As the main residue, the litter poultry generated in the cycle when reused as an input for heating the aviary itself in the form of briquettes, can increase these efficiencies. The use of LPG is more environmentally friendly compared to wood, considering the average demands for the too forms of heating, due to the direct form of heat transfer to the broilers. It is advisable, on hot days, to raise the air speed using the evaporative cooling only in cases of high ambient temperature, as the introduction of water raises the exergy dissipated in the cycle.
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Laukkanen, Mikko. "Project Solaris - Mass and balance analysis tool for a solar powered UAV." Thesis, Mälardalen University, School of Innovation, Design and Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-7449.
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Lessard, Charlotte. "Mass Balance Model of Mercury for the St. Lawrence River, Cornwall, Ontario." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22862.
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We have developed a regional mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental mercury (Hg0), divalent mercury (Hg2+), and methyl mercury (MeHg), in a five compartment environment (air, water, sediments, periphyton, and benthos). Our first objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. Our second objective was to construct a dynamic mass balance model to predict and hindcast mercury concentrations in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model in STELLA®. The inflow of mercury was the major source to this system, accounting for 0.42 mol month-1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month-1, or 63.6% of all losses, and sediment deposition was 0.12 mol month-1, or 27.3% of all losses. The dynamic mass balance model provides estimated results that are consistent with measured data and predicts historical local industrial emissions to be approximately 400 kg year-1. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. This model is useful for predicting and hindcasting mercury concentrations in other aquatic environments because it contains the three main environmental compartments, all forms of mercury, and compartments (e.g. periphyton) not included in previous mercury multi-media models.
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Hart, John 1969. "Mass balance model and field calibration for phosphorus removal from municipal wastewaters." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23368.
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Of the wastewater treatment plants (WTPs) in the province of Quebec that are effecting a phosphorus (P) removal program, chemical addition and precipitation is the primary form of P-removal, with biograss growth and/or enhanced biological P-removal (EBPR) providing secondary removals. An overall P-removal of approximately 66% was achieved at these WTPs in 1994.Dessau Inc. of Laval, McGill University and Ecole Polytechnique were contracted by the Ministry of the Environment and Fauna of Quebec to perform an evaluation of chemical P-removal from Quebec municipal wastewaters and the optimization of existing processes. Part of this evaluation and optimization involved clarifying the mechanisms and interactions during chemical P-removal. Many key models from literature were reviewed, but were not entirely adequate.
A static steady-state P-removal model was therefore developed, accounting for the reactions and removals of soluble and particulate forms of orthophosphate and polyphosphate/organic phosphorus. The model traces the path of each P-fraction throughout the chemical removal process, accounting for P-precipitation and adsorption, as well as reductions of TSS and BOD$ sb5.$ Computer programs were constructed for the model, with specific programs written for primary treatment, activated sludge, biofiltration and facultative aerated lagoons.
Samples were gathered at 11 WTPs during June-July 1994; these field data were used to calibrate the computer programs. Computer program output generally agreed with the field data to within 10%. Several of the WTPs sampled obtained a total-P removal of approximately 90% with metal dosed:P molar ratios often below 1.
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Chin, Chi-pang Henry, and 錢志鵬. "Receptor modelling of particulates pollution in Hong Kong by chemical mass balance." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31253696.
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Rye, Cameron James. "Spatially distributed modelling of regional glacier mass balance : a Svalbard case study." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609569.
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David, Höglin. "Regional and Local Factors Influencing the Mass Balance of the Scandinavian Glaciers." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-311152.
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According to climatic models there will be an increase in the amount of greenhouse gases which results in a warming of the earth where the change will be most prominent in the high latitudes. Glaciers mass balance is a good climate change indicator as the response is fast when climate is changing. Glacier mass balance, area of glaciers, elevation line altitude data for 13 glaciers in Scandinavia as well as North Atlantic oscillation (NAO), Arctic oscillation (AO) and sunspot data where gathered and a principle component analysis (PCA) where made. PCA is a multivariate statistical technique with the goal to extract important information and reduce the dimension of data. Three distinct groupings where found within the data set and was identified as extreme years of North Atlantic Oscillation and Arctic Oscillation and one glacier which had the largest area of the 13 glaciers. The PCA explained that all the variables in the data set is correlated with North Atlantic and Arctic Oscillation to about 40 % and we can conclude that there is a regional and local forcing within our data where the regional (NAO and AO) is of more importance for the variance and for the mass balance.Enligt klimatmodeller kommer en ökning av växthusgaser i atmosfären leda till en ökning av temperaturen på jorden, den ökningen kommer främst att ske på höga latituder. Glaciärer är bra indikation på förändrat klimat på grund av deras korta responstid när klimatet ändrar sig. För tillfället finns det ca 1900 glaciärer utspridda i de Skandinaviska bergen. Eftersom Skandinavien är så avlångt är det en skillnad i meterologiska och klimatiska förhållanden, både i en nord-syd riktning men även i en öst-väst riktning med kontinentala glaciärer i öst och mer marina i väst. Klimat och glaciärdata för 13 olika glaciärer i Skandinavien, 5 från Sverige och 8 ifrån Norge har samlats in och en statistisk analys, principle component analysis (PCA) har gjorts för att se vad som påverkar massbalansen för glaciärerna. De klimat parametrar som har undersökts är Nordatlantsika oscillationen (NAO), Arktiska oscillationen (AO) och solfläckar tillsammans med massbalans, equilibrium line altitude (ELA) och area för glaciärerna. Tre grupperingar har hittats som kan kopplas till olika klimatvariabler och PCA visar extremår för NAO och AO samt en glaciär som har den största arean. PCA analysen visade att alla variabler korrelerade till NAO och AO med omkring 40 % och vi kan dra slutsatsen att det finns en drivande regional och lokal kraft inom vårat dataset där NAO och AO är viktigast för massbalansen.
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Chin, Chi-pang Henry. "Receptor modelling of particulates pollution in Hong Kong by chemical mass balance /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18736063.
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Cimino, Joseph A. "Empirical mass balance calibration of analytical hydrograph separation techniques using electrical conductivity." [Tampa, Fla.] : University of South Florida, 2003. http://purl.fcla.edu/fcla/etd/SFE0000213.
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PIVETTA, TOMMASO FERRUCCIO MARIA. "Gravimetry for monitoring water mass movements in karstic areas." Doctoral thesis, Università degli Studi di Trieste, 2021. http://hdl.handle.net/11368/2988158.
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Karst aquifers represent a significant source of water for about 1/4 of the world’s population. The water circulation in karst occurs mostly underground and it is mainly controlled by alternation of small conduits and large voids present in the rock massif. Such intricate void distribution combined with an irregular recharge provided by the rain results in fast and complex water flows with temporary accumulation of huge water volumes in the voids. The knowledge of the dynamics of such system is usually limited to the areas where a direct access to the vadose zone through speleological exploration is possible. Given the importance of such aquifers and their vulnerability it is important to have a detailed picture of the water dynamics and of the underground water paths.
Gravimetry offers a valid complement to classical hydrologic measurements in order to monitor the recharge process.
In this thesis, I show an innovative integration of gravimetric and hydrologic observations to constrain a hydrodynamic model of the Škocjan cave system (Slovenia). The Škocjan caves hydrology is mostly governed by the allogenic contribution of the Reka River, which during flood event causes the accumulation of several millions of m3 of water in the cave system for few hours. In 2018 I installed a continuous recording gravimeter nearby Škocjan which allowed the detection of several gravity transients related to the local hydrologic contribution.
Gravity observations are sensitive to several other contributions apart the hydrology, such as Earth and marine tides, atmospheric mass redistribution, water mass variations in oceans. All these phenomena superpose their effects and should be carefully evaluated and removed before unveiling the local hydrology contribution. Before discussing the hydrologic gravity signals, the thesis illustrates the efforts in modelling and removing all the non-hydrologic related gravity contributions. The study area is close to the Adriatic Sea, hence global models of tidal and non-tidal ocean (NTO) gravity effects could be inadequate for the correction. I prove that while tidal models are sufficiently accurate to remove the marine tidal influence a dedicated correction of the NTO is required. This was fulfilled by modelling the gravity variations due to a 4D mass model of the NTO constrained by tide gauge observations. The gravity residuals, obtained after reducing the observations for all the non-hydrologic effects, revealed anomalies correlated to the Reka flooding; the transients lasted for 12-24 hours with amplitudes in the range 10-450 nm/s2. I focused my analysis on a large flood event in February 2019 that caused water level variations >90 m inside the caves and gravity variations >400 nm/s2. The gravity and the hydrologic data were used to constrain a hydraulic model of the cave system which approximated the cavity through a series of interconnected conduits with rectangular cross-section. I fitted hydrologic and gravity observations obtaining a 4D model of the water mass variations in the cave system; the model revealed that >3 106 m3 of water were temporary accumulated during the peak’s flood. The inclusion of gravity observations improves water mass budget of the caves, which previously were based relying only on hydrological observations.
Finally, the gravity data allowed to draw some general conclusions on the detectability of water storage variations in karst through gravimetry. I assessed the noise level of the Škocjan gravimeter which is about 10 nm/s2 in the diurnal spectral band and which can be taken as representative of the noise level of a typical spring based gravimeter. Relying on realistic water level variations I estimated the expected gravity signals on surface due to temporary water accumulation in other
caves of the Classical Karst. For all the considered caves the gravity signal is above the noise threshold, suggesting that a remote monitoring of the storage variations is feasible.Karst aquifers represent a significant source of water for about 1/4 of the world’s population. The water circulation in karst occurs mostly underground and it is mainly controlled by alternation of small conduits and large voids present in the rock massif. Such intricate void distribution combined with an irregular recharge provided by the rain results in fast and complex water flows with temporary accumulation of huge water volumes in the voids. The knowledge of the dynamics of such system is usually limited to the areas where a direct access to the vadose zone through speleological exploration is possible. Given the importance of such aquifers and their vulnerability it is important to have a detailed picture of the water dynamics and of the underground water paths. Gravimetry offers a valid complement to classical hydrologic measurements in order to monitor the recharge process. In this thesis, I show an innovative integration of gravimetric and hydrologic observations to constrain a hydrodynamic model of the Škocjan cave system (Slovenia). The Škocjan caves hydrology is mostly governed by the allogenic contribution of the Reka River, which during flood event causes the accumulation of several millions of m3 of water in the cave system for few hours. In 2018 I installed a continuous recording gravimeter nearby Škocjan which allowed the detection of several gravity transients related to the local hydrologic contribution. Gravity observations are sensitive to several other contributions apart the hydrology, such as Earth and marine tides, atmospheric mass redistribution, water mass variations in oceans. All these phenomena superpose their effects and should be carefully evaluated and removed before unveiling the local hydrology contribution. Before discussing the hydrologic gravity signals, the thesis illustrates the efforts in modelling and removing all the non-hydrologic related gravity contributions. The study area is close to the Adriatic Sea, hence global models of tidal and non-tidal ocean (NTO) gravity effects could be inadequate for the correction. I prove that while tidal models are sufficiently accurate to remove the marine tidal influence a dedicated correction of the NTO is required. This was fulfilled by modelling the gravity variations due to a 4D mass model of the NTO constrained by tide gauge observations. The gravity residuals, obtained after reducing the observations for all the non-hydrologic effects, revealed anomalies correlated to the Reka flooding; the transients lasted for 12-24 hours with amplitudes in the range 10-450 nm/s2. I focused my analysis on a large flood event in February 2019 that caused water level variations >90 m inside the caves and gravity variations >400 nm/s2. The gravity and the hydrologic data were used to constrain a hydraulic model of the cave system which approximated the cavity through a series of interconnected conduits with rectangular cross-section. I fitted hydrologic and gravity observations obtaining a 4D model of the water mass variations in the cave system; the model revealed that >3 106 m3 of water were temporary accumulated during the peak’s flood. The inclusion of gravity observations improves water mass budget of the caves, which previously were based relying only on hydrological observations. Finally, the gravity data allowed to draw some general conclusions on the detectability of water storage variations in karst through gravimetry. I assessed the noise level of the Škocjan gravimeter which is about 10 nm/s2 in the diurnal spectral band and which can be taken as representative of the noise level of a typical spring based gravimeter. Relying on realistic water level variations I estimated the expected gravity signals on surface due to temporary water accumulation in other caves of the Classical Karst. For all the considered caves the gravity signal is above the noise threshold, suggesting that a remote monitoring of the storage variations is feasible.
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Eriksson, Rehn Ida. "Mass balance and local characteristics of three glaciers in southern Norway, between 1980 and 2018 : An analysis of the mass balance and the local characteristics of Ålfotbreen, Storbreen and Gråsubreen." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-184671.
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Glaciers are known as climate indicators because of their sensitivity towards climatic perturbations and fluctuations. A majority of the world’s glaciers are currently melting as a response to climatic perturbations. Glaciers in Norway display the same pattern, and the loss of mass have accelerated during the 1990s to this day. The glaciers of interest in this paper is situated in a west to east transect with the maritime Ålfotbreen in the west, to the continental Gråsubreen in the east, with the intermediate Storbreen in between. Differences in the local climate have a significant impact on the future state of glaciers. This paper aims to compare the mass balance, mass turnover and mass balance sensitivity of the three glaciers of interest, between the years 1980 and 2018, to demonstrate the importance of the local climate and characteristics for glacial existence. Mass balance data series of each glaciers’ mass balance was analysed. In addition, development trends of the mean annual summer air temperature for respective glaciers’ region were also conducted. A literature review of relevant reports and publications will be presented and analysed to complement the result of this paper. The results of this paper indicate that the characteristics of respective glacier vary along the increasing continentality of the west to east transect, with the mass balance sensitivity decreasing from west to east. The mass turnover displayed varying patterns, between the years 1980 and 2018. ÅLF had the highest mass turnover for the period and GRÅ the smallest with STO in between. It can be concluded, based on the result of this paper, that the fate of glaciers depends on geographical location and local characteristics. The resemblance between Storbreen and Storglaciären, and the existence of Helagsglaciären who seem to survive against the odds, strengthens the importance of local characteristics.
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Dahl, Magnus. "Appropriate Modelling Complexity: An Application to Mass Balance Modelling of Lake Vänern, Sweden." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4239.
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This work is about finding an appropriate modelling complexity for a mass-balance model for phosphorus in Lake Vänern, Sweden. A statistical analysis of 30 years of water quality data shows that epilimnion and hypolimnion have different water quality and should be treated separately in a model. Further vertical division is not motivated. Horizontally, the lake should be divided into the two main basins Värmlandssjön and Dalbosjön. Shallow near shore ares, bays and areas close to point sources have to be considered as specific sub-basins if they are to be modelled correctly.
These results leads to the use of a model based on ordinary differential equations. The model applied is named LEEDS (Lake Eutrophication Effect Dose Sensitivity) and considers phosphorus and suspended particles. Several modifications were made for the application of the model to Lake Vänern. The two major ones are a revision of the equations governing the outflow of phosphorus and suspended particle through the outflow river, and the inclusion of chemical oxygen demand (COD) into the model, in order to model emissions from pulp and paper mills. The model has also been modified to handle several sub-basins.
The LEEDS model has been compared to three other eutrophication models applied to Lake Vänern. Two were simple models developed as parts of catchment area models and the third was a lake model with higher resolution than the LEEDS model. The models showed a good fit to calibration and validation data, and were compared in two nutrient emission scenarios and a scenario with increased temperature, corresponding to the green house effect.
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Karlsson, Olof Magnus. "Predicting Ecosystem Response from Pollution in Baltic Archipelago areas using Mass-balance Modelling." Doctoral thesis, Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-144120.
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Baltic archipelago areas have high nature values despite being polluted from various antrophogenic activities within the Baltic Sea catchment area and from long-range transport of airborne substances. The discovery of environmental problems in the Baltic Sea in the 1960s led to countermeasures that gradually gave results in reducing the toxic pollution, e.g. from PCBs. Today, much of the environmental management is focused on reducing the effects of eutrophication. There is a demand from society on science to develop strategies that can direct remedial actions so that the cost-effectiveness is maximised. This work focuses on how mass-balance models can be used to understand how coastal ecosystems are controlled by abiotic processes and to predict the response to changes in loading of different substances. Advection, sedimentation and burial are examples of general transport processes that are regulated by morphometrical characteristics, e.g. size, form, effective fetch and topographical openness. This is why different coastal areas have different sensitivity to loading of pollutants. A comparison of six phosphorus and chlorophyll models of different complexity showed that the model performance was not improved with more state variables of total phosphorus (TP) than two water and two sediment compartments. Modelling chlorophyll as a separate state variable did not improve the results for individual values compared to a simple regression against total phosphorus in surface water. Field investigations of the phosphorus content in accumulation sediments along the coast of Svealand showed a distribution pattern that probably is related to differences in the redox status. The average content of mobile phosphorus was much higher than previously found in offshore Baltic sediments indicating that sediments may play an important role for the phosphorus turnover in Baltic archipelago areas. A one-year field study to measure the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in water, sediments and fish during different seasons was carried out in Kallrigafjärden Bay. The collected data set was used to test a mass-balance model for PCCD/F-turnover. It was possible to reproduce the concentrations of different PCDD/F-congeners with high accuracy using a general model approach, including one water compartment and two sediment compartments, indicating that the applied model has the necessary qualifications for successful predictions of PCDD/F-turnover in Baltic coastal areas.Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 736
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Cao, Qianwen. "Mass Balance of Major, Minor and Trace Elements During AFBC Combustion of Fuels." TopSCHOLAR®, 1997. http://digitalcommons.wku.edu/theses/899.
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The proposed ASTM procedures for the determination of 13 major and minor., and 11 trace elements, in solid coal and coke combustion residues by inductively coupled plasma-atomic emission spectrometry (ICP-AES) were checked for routine use. In this study, the ICP analysis values and XRF analysis values of major and minor elements in two kinds of coal and two kinds of limestone were compared. It was shown that over 95% closure of the mass balances of the 24 major, minor, and trace elements was obtained with the proposed ASTM procedure. Also, it was demonstrated that trace elements may be lost through combustion. From six combustion runs, the composition of the fly ashes produced in the FBC burns was determined by XRF analysis. The total carbon, inorganic carbon, and unburned carbon in the fly ashes were also determined. The combustion efficiency of the AFBC system was calculated by comparing the carbonto-iron ratios in the unburned fuel to that in the fly ashes.
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Clendon, Penelope Catherine. "Summertime surface mass balance and atmospheric processes on the McMurdo Ice Shelf, Antarctica." Thesis, University of Canterbury. Geography, 2009. http://hdl.handle.net/10092/2630.
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The aim of this research was to demonstrate the relationship between variations in summertime surface mass balance of the McMurdo Ice Shelf and atmospheric processes. The approach encompassed a broad range of techniques. An existing energy balance mass balance model was adapted to deal with debris-covered ice surfaces and modified to produce distributed output. Point based surface energy and mass balance for two key surfaces of the ice shelf were linked to different synoptic types that were identified using a manual synoptic classification. The distributed model was initialised with distributed parameters derived from satellite remote sensing and forced with data from a regional climate model. Patterns of summertime surface mass balance produced by the distributed model were assessed against stake measurements and with respect to atmospheric processes. During the summers of 2003-2004 and 2004-2005 an automatic weather station (AWS) was operated on bare and debris-covered ice surfaces of the McMurdo Ice shelf, Antarctica. Surface mass balance was calculated using the energy balance model driven by the data from the AWS and additional data from permanent climate stations. Net mass balance for the measurement period was reproduced reasonably well when validated against directly measured turbulent fluxes, stake measurements, and continuously measured surface height at the AWS. For the bare ice surface net radiation provided the major energy input for ablation, whereas sensible heat flux was a second heat source. Ablation was by both melt (70%) and sublimation (30%). At the debris-covered ice site investigated, it is inferred that the debris cover is sufficient to insulate the underlying ice from ablation. Synoptic weather situations were analysed based on AVHRR composite images and surface pressure charts. Three distinct synoptic situations were found to occur during the summers, these were defined as Type A, low pressure system residing in the Ross Sea Embayment; Type B, anticyclonic conditions across region; and Type C, a trough of low pressure extending into the Ross Sea Embayment. A dependence of surface energy fluxes and mass balance on synoptic situation was identified for the bare ice surface. The distributed model was found to produce spatial patterns of mass balance which compared well with stake measurements. Mass balance patterns show that the McMurdo Ice Shelf was generally ablating in the west, and accumulating in the east during summer. Areas of enhanced ablation were found which were likely to be caused by the surface conditions and topographic effects on the wind field. The mean summertime surface mass balance across the entire ice shelf for the 2003-2004 and 2004-2005 summers were –2.5 mm w.e. and –6.7 mm w.e. respectively. The differences between the two summers are inferred to be a result of more frequent type A conditions occurring during the summer of 2004-2005.
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Boström, Björn. "Achieving carbon isotope mass balance in Northern forest soils, soil respiration and fungi /." Örebro : Department of Natural Sciences, Örebro University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-2101.
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