I denna rapport beskrivs en undersökning och jämförelse av två olika sorters segjärn. Detvå materialen som har studerats har varit det segjärnet som används i Parker Hannifinsnuvarande hydraulikmotorer och ett nytt segjärn, vars mekaniska egenskaper har påståttsvara mer fördelaktiga. Målet med arbetet var att få fram en tillförlitlig jämförelse av de olikamaterialen och avgöra om det fanns ett tydligt underlag för att inleda processen av ett byteav material i vissa komponenter i Parker Hannifins produkter.Det utfördes jämförelser mellan de olika materialens mekaniska egenskaper baserade delspå information som redan fanns om materialen och dels på data insamlad vid tester medskärande bearbetning. Förslitning på verktygen vid fräsning studerades tillsammans medskärkraften med olika sorters skärdata. Restspänningar efter ingreppen i de båda materialenmättes med en röntgendiffraktometer.Resultaten gav inga signifikanta indikationer på att ett materialbyte skulle innebära en lägreproduktionskostnad, dock visade analyser att det nya materialet tål att bearbetas fortare ändet traditionella segjärnet och att fler undersökningar bör göras. Efter att ha analyseratmekaniska egenskaper så som hållfasthet, hårdhet, hårdhetsspridning och styvhet kundeslutsatser dras. Det visade sig att det nya segjärnet hade högre hållfasthet och jämnarehårdhet, men det hade även lägre styvhet. Styvheten i materialet är en viktig faktor dåläckage kan uppstå i hydraulikmotorer om materialen inte har tillräckligt hög styvhet.Mätningarna av skärkraften hos de båda materialen tydde på att det kunde uppstå högrestandardavvikelse, eller variationer av skärkraften vid fräsning av det traditionella segjärnet.Eftersom dessa variationer endast visade sig ett fåtal gånger går det inte att entydigtkonstatera att det nya materialet har mer fördelaktiga bearbetningsegenskaper. För att draen sådan slutsats hade det krävts ytterligare analyser på fler detaljer. / This report describes a study and comparison of two different types of ductile iron. Thetwo materials that have been studied have been the ductile iron used in Parker Hannifin'scurrent hydraulic motors and a new ductile iron, whose mechanical properties are said tobe more advantageous. The goal of this study was to obtain a reliable comparison of thedifferent materials and determine if there were clear grounds for initiating the process of achange of material in certain components of Parker Hannifin’s products.Comparisons between the mechanical properties of the materials were based partly oninformation that was already available and partly on data collected through machining trails.The wear on the tools after milling was studied along with the cutting force from variouskinds of cutting data. Residual stresses after the operation in both materials were measuredby an X-ray diffractometer.The results yielded no significant indication that a change of material would result in lowerproduction cost, however, analyses showed that the new material can withstand beingprocessed faster than the traditional ductile iron and that more studies should beconducted. After analyzing the mechanical properties, such as strength, hardness, hardnessvariation and stiffness, conclusions could be drawn. It turned out that the new ductile ironhad higher strength and more uniform hardness, but it also had lower stiffness. Thestiffness of the material is an important factor because if the materials do not havesufficient rigidity, leakage can occur in hydraulic motors. Measurements of the cutting forceof the two materials indicated that there could be a higher standard deviation, orfluctuation of the cutting force during milling of the traditional ductile iron. Since thesevariations only appeared a few times, it is difficult to conclude that the new ductile ironwould be more advantageous when it comes to machining. To be able to draw that kind ofconclusion would require more collected data.

Severe floods caused by heavy autumn rains in year 2000 raised the question whether measures to reduce the damage from high water levels, in the area surrounding lake Glafsfjorden and along the river Byälven down to lake Vänern, are possible. One option is to reduce flow resistance along the river and thereby lower the maximum water level a given inflow would cause. Good knowledge of hydraulic and hydrological conditions is necessary in order to estimate the effect of such flow-reducing measures. In order to quantify such effect a 1-dimensional hydraulic flow model has been set up for the river Byälven using the software package MIKE 11. The model is more detailed, especially concerning topography and bathymetry, than earlier models used for studies of the river. Boundary conditions consist of measured inflows, the level of the lake Vänern and runoff calculated using the HBV-model. The model was calibrated for two different floods and a good fit to measured water levels was obtained for both these periods. Using the calibrated model critical sections, causing much flow resistance during high floods, were identified. With that knowledge different measures to reduce high water levels was adopted to the model both individually and combined with each other and the model was run with boundary conditions mainly from the flood in year 2000. The most radical measures simulated resulted in a lowering of the maximum water in the two largest reservoirs Glafsfjorden and Harefjorden with 78 and 97 cm respectively. A more modest combination of measures gave water levels 48 and 84 cm lower than a model run without changes. Some combinations of relatively small measures lowered the maximum water level by a few decimeters. The simulation results give good guidance to further investigations and decisions of actual changes. The model constitutes a useful tool when making flood maps of the area and if water level forecasts would be needed during future floods. / Allvarliga översvämningar i samband med höstregn år 2000 väckte frågan om det går att vidta åtgärder för att minska skadorna vid höga flöden i området runt Glafsfjorden och längs Byälvens sträckning ner till Vänern. Ett alternativ är att med åtgärder längs älven underlätta vattnets utflöde och på så sätt minska den högsta vattennivå ett givet flöde orsakar. God kunskap om hydrauliska och hydrologiska förhållanden behövs för att bedöma nyttan av olika åtgärdsalternativ. För att kunna avgöra effekterna av olika åtgärdsalternativ har en 1-dimensionell strömningsmodell satts upp för Byälven i programverktyget MIKE 11. Modellen är mer detaljerad, framförallt beträffande höjdinformationen, än tidigare modeller som använts för studier av Byälven varit. Randvillkor till modellen utgörs av registrerade inflöden, Vänerns vattenstånd och avrinning modellerad med HBV-modellen. Modellen har kalibrerats för två översvämningsperioder och god anpassning uppnåddes för de vattenstånd som dessa situationer representerar och med dess hjälp har sedan älven studerats och områden som bromsar flödet har kunnat identifieras. Med kunskap om vilka områden som begränsar flödet mest har ett antal olika åtgärder simulerats i modellen, både var för sig och kombinerade med varandra. Randvillkoren för översvämningen år 2000 behölls och förändringarna lades in i modellen. De extremaste åtgärderna som simulerats resulterade i minskningar av de högsta vattennivåerna i de två största vattenmagasinen Glafsfjorden och Harefjorden med 78 respektive 97 cm. Mer realistiska åtgärdspaket gav minskningar med i storleksordningen 48 respektive 84 cm och även relativt små ingrepp gav minskningar på några decimeter. Simuleringsresultaten ger god vägledning för vidare undersökningar av och beslut om konkreta åtgärder i Byälven. Dessutom utgör modellen ett bra verktyg för att ta fram översvämningskartor och för att prognostisera vattennivåer vid nya översvämningssituationer.

Load sensing pumps in hydraulic system of wheel loaders helps in increasing the energy efficiency of wheel loaders. Present day machines have hydro mechanical load sensing system. After the advent of hydro mechanical load sensing concept, over the years, lots of research has been carried out relevant to electro hydraulic load sensing, trying to control the pump electronically. Currently, Volvo Construction Equipments (VCE) is interested in investigating the possibility of implementing electro hydraulic load sensing system in the wheel loaders. Research works has shown existence of several configurations of electro hydraulic load sensing pumps. Successful simulation results of an electro hydraulic load sensing pump configuration would provide a backing for the proposal of building and testing that configuration of electro hydraulic load sensing pump prototype. Also, the thesis work aims in benchmarking hydraulic system simulation capabilities of AMESim and GT- Suite by simulating the existing hydro mechanical load sensing system in both in both the simulation packages. / The thesis work has been carried out at Virtual Product Development (VPD) division of Volvo Construction Equipments (VCE), Eskilstuna, Sweden.

The system code TRACE is the latest development of the U.S. Nuclear Regulatory Commission (US NRC). TRACE, developed for the analysis of operational conditions, transients and accidents of light water reactors (LWR), is a best-estimate code with two fluid, six equation models for mass, energy, and momentum conservation, and related closure models. Since TRACE is mainly applied to LWR specific issues, the validation process related to innovative nuclear systems (liquid metal cooled systems, systems operated with supercritical water, etc.) is very limited, almost not existing. In this work, essential contribution to the validation of TRACE related to lead and lead alloy cooled systems as well as systems operated with supercritical water is provided in a consistent and corporate way. In a first step, model discrepancies of the TRACE source code were removed. This inconsistencies caused the wrong prediction of the thermo physical properties of supercritical water and lead bismuth eutectic, and hence the incorrect prediction of heat transfer relevant characteristic numbers like Reynolds or Prandtl number. In addition to the correction of the models to predict these quantities, models describing the thermo physical properties of lead and Diphyl THT (synthetic heat transfer medium) were implemented. Several experiments and numerical benchmarks were used to validate the modified TRACE version. These experiments, mainly focused on wall-to-fluid heat transfer, revealed that not only the thermo physical properties are afflicted with inconsistencies but also the heat transfer models. The models for the heat transfer to liquid metals were enhanced in a way that the code can now distinguish between pipe and bundle flow by using the right correlation. The heat transfer to supercritical water was not existing in TRACE up to now. Completely new routines were implemented to overcome that issue. The comparison of the calculations to the experiments showed, on one hand, the necessity of these changes and, on the other hand, the success of the new implemented routines and functions. The predictions using the modified TRACE version were close to the experimental data. After validating the modified TRACE version, two design studies related to the Generation IV International Forum (GIF) were investigated. In the first one, a core of a lead-cooled fast reactor (LFR) was analyzed. To include the interaction between the thermal hydraulic and the neutron kinetic due to temperature and density changes, the TRACE code was coupled to the program system ERANOS2.1. The results gained with that coupled system are in accordance with theory and helped to identify sub-assemblies with the highest loads concerning fuel and cladding temperature. The second design which was investigated was the High Performance Light Water Reactor (HPLWR). Since the design of the HPLWR is not finalized, optimization of vital parameters (power, mass flow rate, etc.) are still ongoing. Since most of the parameters are affecting each other, an uncertainty and sensitivity analysis was performed. The uncertainty analysis showed the upper and lower boundaries of selected parameters, which are of importance from the safety point of view (e.g., fuel and cladding temperature, moderator temperature). The sensitivity study identified the most relevant parameters and their influence on the whole system.

Modern control design is sometimes accompanied by the challenge of dealing with nonlinear systems or plants. In some situations, due to the complexity of the plant and the unavailability of suitable models, the controls engineer opts for developing control schemes based on look-up tables. These tables, typically populated with the steady state inverse input-output characteristics of the plant, are used to compensate the plant via open-loop or closed-loop to solve the control problem. In an effort to present a new alternative, a general theoretical framework for online auto-calibration and control of general nonlinear systems is developed in this dissertation. This technique simultaneously learns the inverse input-state mapping (i.e. the calibration mapping) of the plant while forcing its state to follow a prescribed desired trajectory. The main requirements for the successful application of the novel control law are knowledge of the order of the plant and some generic data to initialize the inverse mapping. This last requirement can be easily fulfilled by using steady-state data or the equilibrium points of the plant. In this approach, the inverse mapping is learned from the current and past states. The learning is accomplished in a composite manner by employing input and state errors. The map is used simultaneously in the feedforward path to control the plant. The performance of the plant subject to this novel controller is validated through simulations and experimental data. The new control method is applied to a novel Electro-Hydraulic Poppet Valve (EHPV). These valves are used in a Wheatstone bridge arrangement for motion control of hydraulic actuators. This is preferred over the conventional use of spool valves due to the energy savings potential. It is shown in this dissertation that this method improves the value of using these types of valves for motion control in hydraulics. This is due to the combination of self-learning (auto-calibration) and better performance for a more efficient operation of hydraulic equipment. Additionally, it is shown that the auto-calibration of the valves can be used for health monitoring of the same, which consequently improves their reliability and expedites maintenance downtime.

Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system / the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.

Tyrolean type water-intake structures are commonly used on mountain rivers to supply water to hydropower stations. The amount of water to be diverted from the main channel is the major concern in these kind of structures and should not be less than the design discharge. In this study a physical model of a Tyrolean type water-intake structure was built at the laboratory and the diverted flow from the main channel through the intake structure having steel racks and perforated plates of different types were measured. The experiments were conducted in two stages. In the first stage the tests were carried out with only steel racks having three different bar openings and slopes, and in the second stage, perforated screens of three different circular openings and screen slopes were used. Applying dimensional analysis to the related parameters of the system the dimensionless terms were defined for the water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel discharge.

Das Vorhaben bestand in der Validierung des gekoppelten neutronenkinetisch-thermohydraulischen Programmkomplexes ATHLET/DYN3D für Siedewasserreaktoren durch Teilnahme an dem OECD/NRC Benchmark zum Turbinenschnellschluss. Das von der OECD und der amerikanischen NRC definierte Benchmark basiert auf einem Experiment mit Schließens des Turbinenschnellschlussventils, das 1977 im Rahmen einer Serie von 3 Experimenten im Kernkraftwerk Peach Bottom 2 durchgeführt wurde. Im Experiment erzeugte das Schließen des Ventils eine Druckwelle, die sich unter Abschwächung bis in den Reaktorkern ausbreitete. Die durch den Druckanstieg bewirkte Kondensation von Dampf im Reaktorkern führte zu einem positiven Reaktivitätseintrag. Der folgende Anstieg der Reaktorleistung wurde durch die Rückkopplung und das Einfahren der Regelstäbe begrenzt. Im Rahmen des Benchmarks konnten die Rechenprogramme durch Vergleiche mit den Messergebnissen und den Ergebnissen der anderen Teilnehmer an dem Benchmark validiert werden. Das Benchmark wurde in 3 Phasen oder Exercises eingeteilt. Die Phase I diente der Überprüfung des thermohydraulischen Modells für das System bei vorgegebener Leistungsfreisetzung im Kern. In der Phase II wurden 3-dimensionale Berechnungen des Reaktorkerns für vorgegebene thermohydraulische Randbedingungen durchgeführt. Die gekoppelten Rechnungen für das ausgewählte Experiment und für 4 extreme Szenarien erfolgten in der Phase III. Im Rahmen des Projekts nahm FZR an Phase II und Phase III des Benchmarks teil. Die Rechnungen für Phase II erfolgten mit dem Kernmodell DYN3D unter Berücksichtigung der Heterogenitätsfaktoren und mit 764 thermohydraulischen Kanälen (1 Kanal/Brennelement). Der ATHLET-Eingabedatensatz für die Reaktoranlage wurde von der Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) übernommen und für die Rechnungen zu Phase III, die mit der parallelen Kopplung von ATHLET mit DYN3D erfolgten, geringfügig modifiziert. Für räumlich gemittelte Parameter wurde eine gute Übereinstimmung mit den Messergebnissen und den Resultaten anderer Codes erzielt. Der Einfluss der Modellunterschiede wurde mit Hilfe von Variantenrechnungen zu Phase II untersucht. So können Unterschiede in der Leistungs- und Voidverteilung in einzelnen Brennelementen auf die unterschiedliche neutronenkinetische und thermohydraulische Modellierung des Reaktorkerns zurückgeführt werden. Vergleiche zwischen ATHLET/DYN3D (parallele Kopplung) und ATHLET/QUABOX-CUBBOX (interne Kopplung) zeigen für räumlich gemittelte Parameter nur geringe Unterschiede. Abweichungen in den lokalen Parametern können im wesentlichen mit der unterschiedlichen Modellierung des Reaktorkerns erklärt werden (geringere Anzahl von modellierten Kühlkanälen, keine Berücksichtigung der Heterogenitätsfaktoren und ein anderes Siedemodell in der Rechnung mit ATHLET/QUABOX-CUBBOX). Die Rechnungen für die extremen Szenarien von Phase III zeigen die Anwendbarkeit des gekoppelten Programms ATHLET/DYN3D für die Bedingungen bei Störfällen, die weit über das Experiment hinausgehen.

Benchmark calculations for the validation of the coupled neutron kinetics/thermohydraulic code complex DYN3D-ATHLET are described. Two benchmark problems concerning hypothetical accident scenarios with leaks in the steam system for a VVER-440 type reactor and the TMI-1 PWR have been solved. The first benchmark task has been defined by FZR in the frame of the international association "Atomic Energy Research" (AER), the second exercise has been organised under the auspices of the OECD. While in the first benchmark the break of the main steam collector in the sub-critical hot zero power state of the reactor was considered, the break of one of the two main steam lines at full reactor power was assumed in the OECD benchmark. Therefore, in this exercise the mixing of the coolant from the intact and the defect loops had to be considered, while in the AER benchmark the steam collector break causes a homogeneous overcooling of the primary circuit. In the AER benchmark, each participant had to use its own macroscopic cross section libraries. In the OECD benchmark, the cross sections were given in the benchmark definition. The main task of both benchmark problems was to analyse the re-criticality of the scrammed reactor due to the overcooling. For both benchmark problems, a good agreement of the DYN3D-ATHLET solution with the results of other codes was achieved. Differences in the time of re-criticality and the height of the power peak between various solutions of the AER benchmark can be explained by the use of different cross section data. Significant differences in the thermohydraulic parameters (coolant temperature, pressure) occurred only at the late stage of the transient during the emergency injection of highly borated water. In the OECD benchmark, a broader scattering of the thermohydraulic results can be observed, while a good agreement between the various 3D reactor core calculations with given thermohydraulic boundary conditions was achieved. Reasons for the differences in the thermohydraulics were assumed in the difficult modelling of the vertical once-through steam generator with steam superheating. Sensitivity analyses which considered the influence of the nodalisation and the impact of the coolant mixing model were performed for the DYN3D-ATHLET solution of the OECD benchmark. The solution of the benchmarks essentially contributed to the qualification of the code complex DYN3D-ATHLET as an advanced tool for the accident analysis for both VVER type reactors and Western PWRs.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 185 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Seagrass communities are composed of numerous organisms that depend on water-column nutrients for metabolic processes. The rate at which these organisms remove a nutrient from the water column can be controlled by physical factors such as hydrodynamic regime or by biological factors such as speed of enzyme reactions. The impact of hydrodynamic regime on rates of nutrient uptake for seagrass (Thalassia testudinum) communities and for organisms that comprise the community (seagrass, epiphytes, phytoplankton, and microphytobenthos) was quantified in a series of field flume experiments employing the use of 15N-labeled ammonium and nitrate. Rates of ammonium uptake for the entire community and for seagrass leaves and epiphytes were significantly dependent on bulk velocity, bottom shear stress, and the rate of turbulent energy dissipation. / ABSTRACT: Relationships between uptake rates and these parameters were consistent with mass-transfer theory and suggest that the effect of water flow on ammonium uptake is the same for the benthos as a whole and for the organisms that form the canopy. In addition, epiphytes on the surface of T. testudinum leaves were shown to depress leaf uptake by an amount proportional to the area of the leaf covered by epiphytes. Water flow influenced rates of nitrate uptake for the community and the epiphytes; however, uptake rates were depressed relative to those for ammonium suggesting that uptake of nitrate was also affected by biological factors such as enzyme activity. Epiphytes reduced uptake of nitrate by the leaves; however, the amount of reduction was not proportional to the extent of epiphyte cover, which provided further evidence that nitrate uptake by T. testudinum leaves was biologically limited. / ABSTRACT: As an additional component of the research, hydrodynamic regime of a mixed seagrass and coral community in Florida Bay was characterized using an acoustic Doppler velocimeter. Hydrodynamic parameters estimated from velocity data were used in mass-transfer equations to predict nutrient uptake by the benthos over a range of water velocity. Measured rates of uptake from field flume experiments conducted in the same community confirmed that hydrodynamic data could be used to accurately predict nutrient transport to the benthos under natural flow conditions. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.