Dissertations / Theses on the topic 'Hydraulic state'
To see the other types of publications on this topic, follow the link: Hydraulic state.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Hydraulic state.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Ferroni, Paolo Ph D. Massachusetts Institute of Technology. "Steady state thermal hydraulic analysis of hydride fueled BWRs." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/41263.
Full textAbstract:
Includes bibliographical references (p. 205-208).Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2006.
(cont.) Since the results obtained in the main body of the analysis account only for thermal-hydraulic constraints, an estimate of the power reduction due to the application of neutronic constraints is also performed. This investigation, focused only on the "New Core" cases, is coupled with an increase of the thickness of the gap separating adjacent bundles from 2 to 5 mm. Under these more conservative conditions, the power gain percentages are lower, ranging between 24% and 43% (depending on the discharge burnup considered acceptable) for the upper pressure drop limit, and between 17% and 32% for the lower pressure drop limit.
(cont.) The benefits of the latter approach are evident since the space occupied by the bypass channel for cruciform control rod insertion becomes available for new fuel and a higher power can be achieved. The core power is constrained by applying thermal-hydraulic limits that, if exceeded, may induce failure mechanisms. These limits concern Minimum Critical Power Ratio (MCPR), core pressure drop, fuel average and centerline temperature, cladding outer temperature and flow-induced vibrations. To limit thermal-hydraulic instability phenomena, core power and coolant flow are constrained by fixing their ratio to a constant value. In particular, each BWR/5 core has been analyzed twice, each time with a different pressure drop limit: a lower limit corresponding to the pressure drop of the reference core and an upper limit 50% larger. It has been demonstrated that, in absence of neutronic constraints and with the maximum allowed pressure drop fixed at the upper limit, the implementation of the hydride fuel yields power gain percentages, with respect to oxide cores chosen as reference, of the order of 23% when its implementation is performed following the "Backfit" approach and even higher (50-70%) when greater design freedom is allowed in the core design, i.e. in the "New Core" approach. Should the maximum allowed pressure drop be fixed at the lower limit, the power gain percentage of the "Backfit" approach would decrease to 17%, while that of the "New Core" approach would remain unchanged, i.e. 50-70%.
This thesis contributes to the Hydride Fuel Project, a collaborative effort between UC Berkeley and MIT aimed at investigating the potential benefits of hydride fuel use in Light Water Reactors (LWRs). Considerable work has already been accomplished on hydride fueled Pressurized Water Reactor (PWR) cores. This thesis extends the techniques used in the PWR analysis to examine the potential power benefits resulting from the implementation of the hydride fuel in Boiling Water Reactors (BWRs). This work is the first step towards the achievement of a complete understanding of the economic implications that may derive from the use of this new fuel in BWR applications. It is a whole core steady-state analysis aimed at comparing the power performance of hydride fueled BWR cores with those of typical oxide-fueled cores, when only thermal-hydraulic constraints are applied. The integration of these results with those deriving from a transient analysis and separate neutronic and fuel performance studies will provide the data required to build a complete economic model, able to identify geometries offering the lowest cost of electricity and thus to provide a fair basis for comparing the performance of hydride and oxide fuels. Core design is accomplished for two types of reactors: one smaller, a BWR/5, which is representative of existing reactors, and one larger, the ESBWR, which represents the future generation of BWRs. For both, the core design is accomplished in two ways: a "Backfit" approach, in which the ex-bundle core structure is identical to that of the two reference oxide cores, and a "New Core" approach, in which the control rods are inserted into the bundles in the form of control fingers and the gap between adjacent bundles is fixed optimistically at 2 mm.
by Paolo Ferroni.
S.M.
2
Pulitzer, Seward Webb 1974. "Feasibility assessment and design of micro hydraulic solid-state transducers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9064.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1998.Includes bibliographical references (p. 179-184).
The performance of a number of mechanical applications could be greatly improved by the introduction of transducers that are capable of exploiting the inherent power densities of piezoelectric materials. The ability of these solid-state materials to exert large forces at high frequencies engenders them with specific power levels (mass normalized) that are often several orders of magnitude greater than conventional transducers, but their utility is offset by their small achievable strains. A novel concept for a device capable of improved solid-state transduction, Micro Hydraulic Solid-State Transducers (MHSTs), is introduced and explored in this thesis. The concept is comprised of two core principles: ( 1) utilization of a hydraulic system consisting of a pump, valves, and a working fluid to rectify the high frequency reciprocations of a piezoelectric drive element into unidirectional motion, and (2) performance enhancement through miniaturization. The goal is a transducer possessing high power densities that is useful in conventional applications. Feasibility of the MHST concept is evaluated by designing, modeling, and simulating a prototype mechanism. The effects of miniattariza~ion on device performance are investigated and an optimal scale is determined. Concept feasibility is based on predicted system performance, existing issues, and manufacturing constraints. It is concluded that the concept is feasible and warrants further development.
by Seward Webb Pulitzer, III.
S.M.
3
Huning, Alexander. "A steady state thermal hydraulic analysis method for prismatic gas reactors." Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52196.
Full textAbstract:
A new methodology for the accurate and efficient determination of steady state thermal hydraulic parameters for prismatic high temperature gas reactors is developed. Two conceptual reactor designs under investigation by the nuclear industry include the General Atomics GT-MHR and the Department of Energy MHTGR-350. Both reactors use the same hexagonal prismatic block, TRISO fuel compact, and circular coolant channel array design.
Steady state temperature, pressure, and mass flow distributions are determined for the base reference designs and also for a range of values of the important parameters. Core temperature distributions are obtained with reduced computational cost over more highly detailed computational fluid dynamics codes by using efficient, correlations and first-principles-based approaches for the relevant thermal fluid and thermal transport phenomena. Full core 3-D heat conduction calculations are performed at the individual fuel pin and lattice assembly block levels. The fuel compact is treated as a homogeneous medium with heat generation. A simplified 1-D fluid model is developed to predict convective heat removal rates from solid core nodes. Downstream fluid properties are determined by performing a channel energy balance down the axial node length. Channel exit pressures are then compared and inlet mass flows are adjusted until a uniform outlet pressure is reached. Bypass gaps between assembly blocks as well as coolant channels are modeled. Finite volume discretization of energy, and momentum conservation equations are then formed and explicitly integrated in time. Iterations are performed until all local core temperatures stabilize and global convective heat removal matches heat generation.
Several important observations were made based on the steady state analyses for the MHTGR and GT-MHR. Slight temperature variation in the radial direction was observed for uniform radial powers. Bottom-peaked axial power distributions had slightly higher peak temperatures but lower core average temperatures compared to top and center-peaked power distributions. The same trend appeared for large bypass gap sizes cases compared to smaller gap widths. For all cases, peak temperatures were below expected normal operational limits for TRISO fuels. Bypass gap flow for a 3 mm gap width was predicted to be between 10 and 11% for both reactor designs. Single assembly hydrodynamic and temperature results compared favorably with those available in the literature for similar prismatic HTGR thermal hydraulic, computational fluid dynamics analyses.
The method developed here enables detailed local and core wide thermal analysis with minimal computational effort, enabling advanced coupled analyses of high temperature reactors with thermal feedback. The steady state numerical scheme also offers a potential for select transient scenario modeling and a wide variety of design optimization studies.
4
Johnson, Jonas. "The Cardiac State Diagram : A new method for assessing cardiac mechanics." Doctoral thesis, KTH, Medicinsk avbildning, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202743.
Full text
5
Hernandez-Ochoa, Abel F. "Conditioning nonlocal steady-state flow on hydraulic head and conductivity through geostatistical inversion." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280279.
Full textAbstract:
Nonlocal moment equations allow one to render optimum predictions of flow in randomly heterogeneous media deterministically conditional on measured values of medium properties and to assess the corresponding predictive uncertainty. I present a geostatistical inverse algorithm for steady-state flow that makes it possible to further condition such predictions and assessments on measured values of hydraulic head and (or) flux. My algorithm is based on recursive finite-element approximations of exact first and second conditional moment equations. Computational efficiency is enhanced through the use of a direct sparse matrix solver. Hydraulic conductivity is parameterized via universal kriging based on unknown values at pilot points and (optionally) measured values at other discrete locations. Correlation among parameter estimates (or priors) is considered in the universal kriging equations. Optimum unbiased inverse estimates of natural log hydraulic conductivity, head and flux are obtained by minimizing a calibration criterion, composed of residuals of head or (and) flux and (possibly) log conductivity, using the Levenberg-Marquardt algorithm. Statistical parameters characterizing the natural variability of hydraulic conductivity can also be estimated using this algorithm. I illustrate the method for superimposed mean uniform and convergent flows in a bounded two-dimensional domain under various conditions for a range of parameters. My examples illustrate how conductivity and head data act separately or jointly to reduce parameter estimation errors and model predictive uncertainty. Over-parameterization is seen to create zones of high mean conductivity, in which flux prediction is more uncertain than is in other regions. It is found that a regular distribution of pilot points works better than does an irregular layout and that the number of pilot points should be as close as possible to the number of head data while maintaining parameters reasonably uncorrelated. Head and flux predictions are very satisfactory for cases with either log conductivity variance or integral scale between one and four, though prediction quality deteriorates with either larger variances or shorter integral scales. The method may perform satisfactorily in cases with no conductivity measurements and only a few head data.
6
Sidky, M. Homayun. "Irrigation and state formation in Hunza: the cultural ecology of a hydraulic kingdom /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487854314871857.
Full text
7
Andrén, Jakob. "An Overview of State-of-the-art Hydraulic Conductivity Measurements in Coarse Grained Materials." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-445699.
Full textAbstract:
Embankment dams are made from soil materials of varying sizes and widely used all over the world.When constructing these, knowing the hydraulic conductivity (K) of the soil materials is a keyparameter in order to construct safe embankment dams. A knowledge gap regarding K measurementsin coarse grained soils has been identified. This thesis aims to provide a theoretical overview ofpresent day state-of-the-art methods for measuring hydraulic conductivity and the controllingcharacteristics for K. Coarse grained soils refers to a soil with the coarsest grain fraction being > 20mm and/or have a K > 10-4m/s. It was found that the fixed wall permeameter is the most suitable laboratory method. In the field, itis possible to estimate K using tracer methods, these however show more potential for leakagepathway detection. Common for all K measurement methods are the controlling characteristics of K,grain size distribution, pore geometry, degree of compaction, particle movement and flow regime.These need to be considered when testing to produce useful measurements. If the relationshipbetween flow velocity and hydraulic head is non-linear, Darcy's law is not valid for calculating K.Fyllnadsdammar är uppbyggda av jord och sprängsten av olika storlekar och finns över hela världen.Att känna till den hydrauliska konduktiviteten (K) av de olika lagren är viktigt för att kunna byggadessa på ett säkert och hållbart sätt. Det har identifierats en bristande kunskap angående K mätningar igrovkorniga jord- och stenmaterial. Målet med denna uppsats är att presentera en teoretisk översikt avden senaste kunskapen inom K mätningar i grovkorniga jord- och stenmaterial och vilka egenskapersom avgör ett materials K. Grovkorniga jord- och stenmaterial syftar till material där den grövstakornstorleken är > 20 mm och/eller har ett K > 10-4m/s. För laboratorie mätningar är en permeameter med en solid vägg den mest lämpliga metoden. Förfältmätningar är det möjligt att mäta K med hjälp av spårämnen, men dessa har mer potential för attupptäcka läckage vägar i fyllnadsdammar. De faktorer som avgör ett materials K ärkornstorleksfördelningen, geometrin av porerna, graden av kompaktering, partikelrörelse ochflödestyp. För att producera mätningar som är användbara behöver dessa faktorer kontrolleras. Omsambandet mellan hydrauliskt huvud och flödeshastighet är icke linjärt kan K inte beräknas genomDarcy´s lag.
8
Elsheikh, Mutasim Mohamed. "A Numerical and Experimental Investigation of Flow Induced Noise In Hydraulic Counterbalance Valves." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5683.
Full textAbstract:
The main objective of this study is to explore the complex fluid flow phenomena that result in the generation of a high frequency noise in counterbalance valves through an experimental and numerical investigation of the flow. Once the influence of the different components involved in noise generation is established, a secondary objective is the introduction of design modifications that eliminate the undesired effect without altering the operation envelope or the performance of the valve.
A hydraulic test bench was used to carry out an experimental investigation of the noise generation process. A computer based data acquisition system was used to record pressure fluctuations, flowrates and hydraulic oil temperatures in a production valve under a variety of operational conditions. Extensive experimental measurements and numerical modeling lead to the hypothesis that noise generation is the result of an acoustic resonance triggered by shear layer instability at the valve inlet. The pressure gradients developed when the shear layer entrains the stagnant fluid in the valve main cavity cause the layer to become unstable and oscillate. The oscillation frequency will depend on a great number of factors such as valve geometry, pressure and velocity gradients and the density and viscosity of the fluid. It is postulated that the observed noise is generated when this frequency matches one of the resonant frequencies of the valve cavity.
The proposed mechanism is theoretically poorly understood and well beyond simplified analysis, its accurate numerical simulation is computational very intensive requiring sophisticated CFD codes. The numerical investigation was carried out using STAR–CCM+, a commercially available CFD code featuring 3-D capabilities and sophisticated turbulence modeling. Streamline, pressure, velocity-vector and velocity-scalar plots were obtained for several valve configurations using steady and unsteady state flow simulations.
An experimental and numerical analysis of an alternative valve geometry was carried out. Experimental results demonstrated a greatly reduced instability range. The numerical analysis of the unsteady behavior of the shear-layer streamlines for both valves yielded results that were compatible with the experimental work.
The results of this investigation promise a great positive impact on the design of this type of hydraulic valves.
9
Hassan, Aymane. "Handling river floating debris for dam safety – the state of the practice." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-289387.
Full textAbstract:
This study reviews the current knowledge and state of the practice for handling floating debris for dam safety. This report is a guidance to improve the understanding of risks of floating debris for dam safety and of countermeasures for risk reduction. The strengths and limitations of current approaches related to dam vulnerability assessment and handling strategies are discussed and recommendations are provided. Several countries experienced issues with floating debris which often led to severe damages to dam spillways. High and extreme flood events could be responsible for similar incidents in Sweden which requires to systematically assess dam vulnerability to floating debris and examine suitable countermeasures. A vulnerability assessment involves investigating the potential for debris production, for debris transport to the dam facility and for blockage and drawdown at spillways. Various concepts for reducing the vulnerability of dam spillways to floating debris were presented in the technical literature. Countermeasures for floating debris management based on a river perspective approach involve controlling the debris yield produced in a catchment, the interception of floating debris in tributaries and reservoirs and measures taken at dam spillways to facilitate floating debris passage. Floating debris management often requires opting for a combination of suitable and cost-efficient measures rather than a single line of defense.
10
Richartz, Achim. "State of the art digital on-board-electronics vs. potentially disruptive control architectures for hydraulic valves." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71191.
Full textAbstract:
Currently discussed trends and new technologies regarding cloud or edge computing imply that even most recent designs and functionalities of digital on-board-control electronics may be outdated and eventually will totally disappear. Additionally, those new technologies attract potential users by promises like new use cases e.g. predictive maintenance or a simplified architecture and reduced installation efforts. On the other hand, automation levels and subsequent requirements are often mixed up or discussed too generally. Nevertheless, what is the rue situation today and in the upcoming years? This paper elaborates the potentials of both approaches – state of the art on-board-control electronics and potentially disruptive control architectures for hydraulic valves in order to take the right decision and reflect the pros and cons for each topology by:
a) Architecture of automation: In Terms of strongly hierarchical or multidimensional connected systems.
b) Requirement of installation: By reflecting the dedicated ecosystems, on levels like plant, machine, subsystems.
c) Maturity of technology: Looking on the user’s perspective.
d) Safety and security: From legal and conformity aspects.
e) Performance needs by specific task: In comparing standard to demanding real life applications.
11
Zhang, Mingyang. "Detailed Heat Transfer Measurements of Various Rib Turbulator Shapes at Very High Reynolds Numbers Using Steady-state Liquid Crystal Thermography." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/81859.
Full textAbstract:
In order to protect gas turbine blades from hot gases exiting the combustor, several intricate external and internal cooling concepts are employed. High pressure stage gas turbine blades feature serpentine passages where rib turbulators are installed to enhance heat transfer between the relatively colder air bled off from the compressor and the hot internal walls. Most of the prior studies have been restricted to Reynolds number of 90000 and several studies have been carried out to determine geometrically optimized parameters for achieving high levels of heat transfer in this range of Reynolds number. However, for land-based power generation gas turbines, the Reynolds numbers are significantly high and vary between 105 and 106. Present study is targeted towards these high Reynolds numbers where traditional rib turbulator shapes and prescribed optimum geometrical parameters have been investigated experimentally. A steady-state liquid crystal thermography technique is employed for measurement of detailed heat transfer coefficient. Five different rib configurations, viz., 45 deg., V-shaped, inverse V-shaped, W-shaped and M-shaped have been investigated for Reynolds numbers ranging from 150,000 to 400,000. The ribs were installed on two opposite walls of a straight duct with aspect ratio of unity. For very high Reynolds numbers, the heat transfer enhancement levels for different rib shapes varied between 1.3 and 1.7 and the thermal hydraulic performance was found to be less than unity.Master of Science
12
Chu, Hsuan-Wen. "A Stormwater Management Model for California Polytechnic State University Campus." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1977.
Full textAbstract:
Developments that have been taking place on Cal Poly campus over the years have altered the natural hydrology of the area. Stormwater management practices could help reduce the impacts of these developments. Computer models can help to design effective and economical stormwater management solutions at a watershed scale. As such, the objective of this study was to develop a stormwater management model for Cal Poly campus. The model was developed based on the utility data obtained from the university and other watershed data available from open sources. Field surveys were conducted to address some anomalies in the utility data, and streamflow monitoring was performed. The model was calibrated using the streamflow data measured during this study. The calibration effort significantly improved the prediction accuracy of the model. The calibrated model was then used to analyze the hydrologic performance of implementing LID systems for two projects that Cal Poly plans to build. Permeable Pavements (PPs) and Bioretention Cells (BRCs) were the LID types examined. The LIDs were evaluated based on peak flow and runoff volume reductions they would achieve. The potential reductions were compared for current conditions and the proposed project if LIDs were implemented, and for inflows to the LIDs and outflows from the LIDs. The results indicate that implementing a PP system for the proposed student apartment at the current H-1 and R-1 parking lots and a BRC system for the proposed engineering project facilities at the current H-2 parking lots will significantly reduce peak flow and runoff volume. Overall, the developed model will help the university with the traditional stormwater management practices such as flood control and to identify effective LID practices for future developments. Limitations of the current model and recommendations on how to improve the model are also discussed.
13
Zhang, Xi. "SPATIAL ESTIMATION OF HYDRAULIC PROPERTIES IN STRUCTURED SOILS AT THE FIELD SCALE." UKnowledge, 2019. https://uknowledge.uky.edu/pss_etds/117.
Full textAbstract:
Improving agricultural water management is important for conserving water during dry seasons, using limited water resources in the most efficient way, and minimizing environmental risks (e.g., leaching, surface runoff). The understanding of water movement in different zones of agricultural production fields is crucial to developing an effective irrigation strategy. This work centered on optimizing field water management by characterizing the spatial patterns of soil hydraulic properties. Soil hydraulic conductivity was measured across different zones in a farmer’s field, and its spatial variability was investigated by using geostatistical techniques. Since direct measurement of hydraulic conductivity is time-consuming and arduous, pedo-transfer functions (PTFs) have been developed to estimate hydraulic conductivity indirectly through more easily measurable soil properties. Due to ignoring soil structural information and spatial covariance between soil variables, PTFs often perform unsatisfactorily when field-scale estimations of hydraulic conductivity are needed. The performance of PTFs in estimating hydraulic conductivity in the field was therefore critically evaluated. Due to the presence of structural macro-pores, saturated hydraulic conductivity (Ks) showed high spatial heterogeneity, and this variability was not captured by texture-dominated PTF estimates. However, the general spatial pattern of near-saturated hydraulic conductivity can still be reasonably generated by PTF estimates. Therefore, the hydraulic conductivity maps based on PTF estimates should be evaluated carefully and handled with caution. Recognizing the significant contribution of macro-pores to saturated water flow, PTFs were further improved by including soil macro-porosity and were proven to perform much better in estimating Ks compared with established PTFs tested in this study. Additionally, the spatial relationship between hydraulic conductivity and its potential influencing factors were further quantified by the state-space approach. State-space models outperformed current PTFs and effectively described the spatial characteristics of hydraulic conductivity in the studied field. These findings provided a basis for modeling water/solute transport in the vadose zone, and sitespecific water management.
14
Gossard, Justin. "Numerical Simulation of the Steady-State, Thermal-Hydraulic Performance of Microchannel and Minichannel Evaporators with Headers and Louvered Fins." Miami University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1323289158.
Full text
15
Villanueva, Evelyn. "Risk assessment of rock surface spillway erosion using parametric studies." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07022007-155027.
Full text
16
Caliskan, Hakan. "Modeling And Experimental Evaluation Of Variable Speed Pump And Valve Controlled Hydraulic Servo Drives." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611090/index.pdf.
Full textAbstract:
In this thesis study, a valveless hydraulic servo system controlled by two
pumps is investigated and its performance characteristics are compared with a
conventional valve controlled system both experimentally and analytically. The
two control techniques are applied on the position control of a single rod linear
actuator. In the valve controlled system, the flow rate through the actuator is
regulated with a servovalvewhereas in the pump controlled system, two variable speed pumps driven by servomotors regulate the flow rate according to the needs of the system, thus eliminating the valve losses. To understand the dynamic behaviors of two systems, the order of the differential equations defining the system dynamics of the both systems are reduced by using the fact that the dynamic pressure changes in the hydraulic cylinder chambers become linearly dependent on leakage coefficients and cylinder chamber volumes above and below some prescribed cut off frequencies. Thus the open loop speed response of the pump controlled and valve controlled systems are defined by v second order transfer functions. The two systems are modeled in MATLAB Simulink environment and the assumptions are validated. For the position control of the single rod hydraulic actuator, a linear state feedback control scheme is applied. Its state feedback gains are determined by using the linear and linearized reduced order dynamic system equations. A linear Kalman filter for pump controlled system and an unscented Kalman filter for valve controlled system are designed for estimation and filtering purposes. The dynamic performances of both systems are investigated on an experimental test set up developed by conducting open loop and closed loop frequency response and step response tests. MATLAB Real Time Windows Target (RTWT) module is used in the tests for application purposes.
17
Mancilla, Alarcón Cristhian A. "Hydrodynamic loadings and responses of a floating guardwall a fluid-structure interaction problem /." Master's thesis, Mississippi State : Mississippi State University, 2005. http://library.msstate.edu/content/templates/?a=72.
Full text
18
Muller, Curtis Joseph 1959. "A multi-step steady-state inverse method for the determination of unsaturated hydraulic conductivity in soil columns: A new parameter estimation technique." Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/278254.
Full textAbstract:
A problem common to many studies involving the use of unsaturated flow and chemical models is determining a representative expression for the value of unsaturated hydraulic conductivity K(ψ). A new steady-state inverse methodology called the multi-step steady-state outflow method (MSSOM) is presented here for the determination of unsaturated hydraulic conductivity. The method offers a practical alternative for the estimation of K(ψ) using either the exponential model, three-parameter model, or the van Genuchten formulations for K(ψ), a global-optimization simplex routine (MSSOM.EXE), and simple outflow data from a one-dimensional column experiment. The inverse technique was applied to a coarse sand and both the wetting an drying curves were well within the range of K(ψ) expected. Conductivity data from four other soils in the literature were then fitted using a curve fitting routine (RETC.F77) by van Genuchten, 1985 and compared to the inverse solution from the MSSOM model. The parameters for the K(ψ) expressions from both RETC and the MSSOM inverse model agreed well. Additional refinement of the multi-step steady-state outflow laboratory apparatus and the optimization program MSSOM.EXE are needed however to further improve the method.
19
Rambaks, Andris, Filipp Kratschun, Carsten Flake, Maren Messirek, Katharina Schmitz, and Hubertus Murrenhoff. "Computational approach to the experimental determination of diffusion coefficients for oxygen and nitrogen in hydraulic fluids using the pressure-decay method." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71099.
Full textAbstract:
In the presented paper, the applicability of pressure-decay methods to determine the diffusivities of gases in hydraulic fluids is analysed. First, the method is described in detail and compared to other measurement methods. Secondly, the thermodynamics and the mass transfer process of the system are studied. This results in four different thermodynamic models of the gaseous phase in combination with two diffusion models. Thirdly, the influence of the models on the pressure-decay method is evaluated computationally by examining the diffusion process of air in water as all system parameters are available from literature. It is shown that ordinary pressure-decay methods are not applicable to gas mixtures like air and therefore a new method for calculating the diffusivities is suggested.
20
McKillip, Michael Lee. "Coupling the Hydrodynamic and Water Quality Model CE-QUAL-W2 With a Multi-Trophic Fish Bio-Energetics Model for Lake Roosevelt, Washington." PDXScholar, 2008. https://pdxscholar.library.pdx.edu/open_access_etds/3078.
Full textAbstract:
Grand Coulee Dam created Franklin D. Roosevelt Lake as part of the Columbia Basin Project. Located in northeastern Washington State, the Project provides economically important hydropower (19 billion kilowatt hours per year), irrigation (225,000 ha), flood control, and sport fishing ($5 to 20 million annually). A good system understanding aids in balancing these beneficial uses for the 230 km long reservoir. The reservoir's atypical 45-day mean residence time is much shorter than a typical lake, and much longer than for a riverine dam. The spring freshet requires drawdowns of 15 to 20 m for flood control—the driving characteristic of reservoir operations.
A physically based two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 Version 3.5 (Cole and Wells, 2006), is coupled with a fish bioenergetics model based on the Stockwell and Johnson model (1997, 1999) to examine the effects of hydrodynamics on the reservoir algae-zooplankton-kokanee food web. This model was applied and calibrated to Lake Roosevelt with model improvements of multiple zooplankton compartments and zooplankton omnivory. Calibration parameters included temperature, dissolved oxygen, nutrients, algae, and zooplankton. The fish bioenergetics model is applied over the entire reservoir model space to generate a spatial and temporal fish growth potential distribution. The fish model refinements include sub-daily time-steps and an optimized vertical foraging strategy.
The linked model suggests that kokanee fish growth potential is seasonally limited by both warm water and prey densities. While the lake ecology is significantly affected by the reservoir operations in general, the pelagic fish growth potential did not appear sensitive to minor changes in reservoir operations. However, the model suggests that the advantageous foraging locations shift seasonally and that optimal foraging strategies are dependent on fish size.
21
Clarkberg, Jasper W. "Regulatory Uncertainty and the Natural Gas Industry in the US." Oberlin College Honors Theses / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=oberlin1495560884199246.
Full text
22
Шуров, Валентин Андрійович. "«Азійський спосіб виробництва» та проблема розвитку марксистської соціальної теорії (за матеріалами дискусії 20-30 х років ХХ ст. в СРСР)." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/35914.
Full textAbstract:
Концепція «азійського способу виробництва» згадувалася в працях Карла Маркса, проте не отримала належної уваги та залишилася незавершеною. Витоки цієї концепції прослідковуються в працях класиків наукової думки XVIII та XIX століть – Ш. Монтеск’є, А. Сміта, Г. В. Ф. Гегеля. Після смерті Маркса продовжив розвивати цю концепцію К. А. Віттфогель. Цю концепцію можна охарактеризувати як єропоцентричну. В 20-30тих роках ХХ століття в СРСР відбувалася дискусія щодо «азійського способу виробництва», в якій брали участь радянські марксисти та сходознавці. Не дивлячись на відсутність безпосередніх висновків з дискусії, в подальшому висновком стала відмова від концепції на офіційному рівні та створення прогресивної моделі розвитку людства, так званої “п’ятичленки”, тобто моделі з п’яти послідовних формацій. Метою моєї роботи було визначення основних протиріч навколо концепції «азійського способу виробництва» та визначення можливих шляхів вирішення цих протиріч в експертному інтерв’ю. В ході роботи були виявлені ці протиріччя та оформлені у вигляді питань до експертів. Я приходжу до висновку про європоцентричність поглядів дослідників, визначний вплив політичної кон’юнктури на причини та висновки дискусії та вельми високий евристичний потенціал концепції в рамках марксистської теорії.The concept of the "Asian mode of production" was mentioned in the works of Karl Marx, but did not receive due attention and remained incomplete. The origins of this concept can be traced in the works of the classics of scientific thought of the XVIII and XIX centuries - S. Montesquieu, A. Smith, G. Hegel. After Marx's death, Karl Wittfogel continued to develop this concept. This concept can be described as eurocentric. In the 1920s and 1930s, there was a discussion in the USSR about the "Asian mode of production," in which Soviet marxists and orientalists took part. Despite the lack of direct conclusions from the discussion, the subsequent conclusion was the rejection of the concept at the official level and the creation of a progressive model of human development, the so-called "five members". The aim of my work was to identify the main contradictions surrounding the concept of the "Asian mode of production" and to identify possible ways to resolve these contradictions in an expert interview. During my work, these contradictions were identified and formalized in the form of questions to experts. I come to the conclusion that views of researches were eurocentric, the influence of the political situation on the causes and conclusions of the discussion was significant, and the heuristic potential of the concept within marxist theory is very high.
23
Higginson, Noel Nelson John. "Evaluation of hydraulic resistance in single and two-stage rivers." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317469.
Full text
24
Escuret, Jean-Francois. "The prediction and active control of surge in multi-stage axial-flow compressors." Thesis, Cranfield University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333133.
Full text
25
Petroutson, William D., Jeffery B. Bennett, Roderic A. Parnell, and Abraham E. Springer. "Hydraulic-Conductivity Measurements of Reattachment Bars on the Colorado River." Arizona-Nevada Academy of Science, 1995. http://hdl.handle.net/10150/296453.
Full textAbstract:
From the Proceedings of the 1995 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 22, 1995, Northern Arizona University, Flagstaff, Arizona
26
Wang, Yu-Li, Tian-Chyi Jim Yeh, Jet-Chau Wen, Shao-Yang Huang, Yuanyuan Zha, Jui-Pin Tsai, Yonghong Hao, and Yue Liang. "Characterizing subsurface hydraulic heterogeneity of alluvial fan using riverstage fluctuations." ELSEVIER SCIENCE BV, 2017. http://hdl.handle.net/10150/623615.
Full textAbstract:
The objective of this study is to demonstrate the ability of riverstage tomography to estimate 2-D spatial distribution of hydraulic diffusivity (D) of Zhuoshui River alluvial fan, Taiwan, using groundwater level data from 65 wells and stream stage data from 5 gauging stations. In order to accomplish this objective, wavelet analysis is first conducted to investigate the temporal characteristics of groundwater level, precipitation, and stream stage. The results of the analysis show that variations of groundwater level and stream stage are highly correlated over seasonal and annual periods while that between precipitation is less significant. Subsequently, spatial cross-correlation between seasonal variations of groundwater level and riverstage data is analyzed. It is found that the correlation contour map reflects the pattern of sediment distribution of the fan. This finding is further substantiated by the cross-correlation analysis using both noisy and noise-free groundwater and riverstage data of a synthetic aquifer, where aquifer heterogeneity is known exactly. The ability of riverstage tomography is then tested with these synthetic data sets to estimate D distribution. Finally, the riverstage tomography is applied to the alluvial fan. The results of the application reveal that the apex and southeast of the alluvial fan are regions with relatively high D and the D values gradually decrease toward the shoreline of the fan. In addition, D at northern alluvial fan is slightly larger than that at southern. These findings are consistent with the geologic evolution of this alluvial fan. (C) 2017 Elsevier B.V. All rights reserved.
27
Kratschun, Filipp, Jens Köhne, Peter Kloft, Heiko Baum, and Katharina Schmitz. "One dimensional unsteady model of a hydropneumatic piston accumulator based on finite volume method." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71089.
Full textAbstract:
Hydraulic piston accumulators play a major role especially within the field of stationary hydraulics. The calculation of the amount of hydraulic energy which can be stored in such an accumulator is crucial when it comes to a precise system design. The knowledge of the temperature and pressure within the accumulator is required in order to calculate the amount of energy to be stored. The state of the art solution to estimate the state of change of such an accumulator is the implementation of a costly measurement system within the accumulator which tracks the position of the piston. The goal of this paper is to develop and to analyse a time efficient simulation approach for the gaseous phase within a piston accumulator depending on the accumulator’s load cycle. Temperature, pressure, density and velocity profiles inside of the gaseous phase are calculated transiently in order to achieve that goal. The simulation model is derived in one dimensional environment to save computational effort. Having derived a valid model of the gaseous phase it will be possible in future works to replace the expensive position measurement system by pressure and temperature transducers and then use the model to calculate the position of the piston and therefore estimate the state of change.
28
Bagour, Mohammed H., and Donald F. Post. "An Evaluation of Methods to Measure the Saturated Hydraulic Conductivity of Soils." Arizona-Nevada Academy of Science, 2000. http://hdl.handle.net/10150/296564.
Full text
29
Bengtsson, Robert. "Evaluating new pilot stage concept." Thesis, Linköping University, Department of Management and Engineering, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11436.
Full textAbstract:
This report is a first practical study of micro valves for hydraulics, manufactured by Microstaq Inc. who uses, for hydraulics, new materials and new actuating technologies. The purpose is to evaluate if, in the future, there is any possibility of complementing or exchanging the classical use of electro magnetic solenoids in electro hydraulic applications with this new technology. The valves studied are of MEMS-type (Micro Electro Mechanical Systems), which are etched out of silicon and has an electro thermic actuation. During the study it showed that this new valve technology had some teething troubles. The valves had proplems managing high pressure drops, both regarding strength of materials and performance. If you let the manufacturers further develop this technology there are great potentials for using this in future hydraulic systems.
30
Blair, Timothy. "Stage discharge estimation using a 1d river hydraulic model and spatially-variable roughness." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/17412.
Full textAbstract:
Stage-discharge relations (rating curves) are integral to stream gauging, yet the existing empirical calibration methods are expensive, particularly in remote areas, and are limited to low flows. Numerical modelling can provide stage-discharge relations from a single site survey, reducing the overall cost, and can be fit to changing surface conditions. This study explores a one-dimensional model to calculate theoretical stage-discharge relations for four field sites in British Columbia that range in bed stability, bed structure, hydrology and sediment supply. However, due to the non-linear relation between flow and roughness we do not assume the conventional reach-averaged roughness and instead employ a spatially-distributed roughness model. Furthermore, based on local grain size distribution and refined field survey technique, new formulae for wetted perimeter, flow area, and flow depth were developed that eliminate commonly held modelling assumptions and reduce topographic error. The results show (1) good agreement with Water Survey of Canada measurements, (2) distributed roughness provided an improvement over spatially-averaged roughness, (3) spatial variability of the geomorphology within the channel reach leads to shifts in the stage-discharge relations and high sediment amplifies those shifts, and (4) the relations must be re-evaluated following events that mobilize the bed. The method can be used to estimate high flows and flows in remote locations and it does not require calibration.
31
Lane, L. J., T. J. Ward, and J. J. Stone. "Evaluation of Hydrologic and Hydraulic Procedures for Small Urban Watersheds in the Southwest." Arizona-Nevada Academy of Science, 1985. http://hdl.handle.net/10150/296362.
Full textAbstract:
From the Proceedings of the 1985 Meetings of the Arizona Section - American Water Resources Association and the Hydrology Section - Arizona-Nevada Academy of Science - April 27, 1985, Las Vegas, NevadaHydrologic and hydraulic design procedures developed by the Pima County Department of Transportation and Flood Control District were proposed for use by the Department of Transportation, Engineering Division of the City of Tucson, Arizona. These procedures were evaluated with respect to their reasonableness of approach and in comparison with other methods and existing data used to derive similar methodology and standards. The proposed criteria/methodology were found to be consistent with procedures used in other cities in the Southwest, and with the current state of the art in urban hydrology and hydraulic engineering practices and procedures. However, locally derived rainfall intensity -duration relationships were found to be superior to regionally based relationships, and minor modifications were suggested for channel design procedures.
32
Chen, Zhenduo. "Le mouvement migratoire provoqué par la construction du barrage de Xin’an Jiang en Chine : politique, acteurs, communauté." Thesis, Paris, EHESS, 2020. http://www.theses.fr/2020EHES0079.
Full textAbstract:
Cette thèse traite les enjeux du mouvement migratoire provoqué par la construction des grands barrages en Chine, en englobant certains aspects de l’histoire chinoise et le contexte de la modernisation du 20e siècle par une méthodologie multidisciplinaire en sciences sociales. Elle interroge les domaines fondamentaux : politique, acteurs, communauté, en tant qu'éléments constitutifs de la migration de barrage, qui relève également du concept chinois de migration, des processus institutionnels de la gouvernance hydraulique, de l'État-nation moderne, et plus largement, du rapport entre l’État et la société par le biais de moyens institutionnels : les racines, la bureaucratie, la sovietisation, etc. Le mouvement migratoire lié à la construction du barrage dans le contexte chinois est un mouvement multisujets/acteurs, mobilisé principalement selon les dynamiques de la relation État-société. Une étude de terrain sur le site du barrage de Xin’an Jiang, un des trois grands barrages « construits indépendamment par les Chinois nous-même » vient nourrir notre recherche dans des dimensions historique et géographique, révélant entre autres l’institution d’ingénierie, la formation de la migration de barrage, le déracinement, la nouvelle communauté constituée par les mouvements, qui façonnent les subjectivités et les performances des différents acteurs des mouvements autour la migration de barrage du Xin’an Jiang. Cette analyse holistique, structurée et s morphologique cherche à comprendre les relations complexes et les transformations qui opèrent pendant la construction des grands barrages et la migration forcée qui l'accompagne dans l'objectif de mettre en place une économie planifiée nationale et une nation chinoise puissante et moderne. Cette thèse montre que la Chine en cours de modernisation se dirige vers une société déracinée et en suspension par rapport sa tradition de Xiangtu shehui. Le mouvement migratoire de barrage nous permet de saisir ce changement mu par une volonté d'autonomie, dont l'avenir semble incertain, et les enjeux d’autonomieThe doctoral thesis deals with the challenges of the emigrant movement caused by the construction of large dams and reservoirs in China, by including certain aspects of Chinese history and the context of modernization of the 20th century. We will study this subject through a multidisciplinary methodology in social sciences, and focus the questions on some fundamental areas: politics, actors, community. We study these constitutive elements of reservoir immigration, which also comes under the Chinese concept of migration, the institutional processes of hydraulic governance, the modern nation state, and more broadly, the relationship between the state and society through institutional means: roots in traditional society, bureaucracy, sovietization, etc. We think that the movement linked to the construction of the dam in the Chinese context is a multi-subject / actor movement, mobilized mainly according to the dynamics of the state-society relationship. A field study on the Xin'an Jiang dam and reservoir, one of the three large dams "built independently by the Chinese ourselves" comes to feed our research in historical and geographic dimensions, revealing among other things the engineering institution , the formation of the emigration and immigration, uprooting, the new community formed by the movements, which shape the subjectivities and the performances of the different actors of the movements around the the construction of dam and reservoir of Xin'an Jiang. This holistic, structured and social morphological analysis seeks to understand the complex relationships and transformations that operate during the construction of large dams and the forced migration that accompanies it with the objective of establishing a national planned economy and a powerful Chinese nation. Our research shows that China, which is in the process of modernization, is moving towards a society uprooted and suspended from its tradition of Xiangtu shehui. The movement by the construction of big dam and reservoir allows us to grasp this change driven by a future for autonomy, which seems uncertain but creates a new subject for modernisation
33
Wang, Yu-Li Eric, and Yu-Li Eric Wang. "Characterizing Subsurface Hydraulic Characteristics at Zhuoshui River Alluvial Fan, Taiwan." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/623152.
Full textAbstract:
The objective of this study is to estimate 2-D spatial distribution of hydraulic conductivity (Ks) of Zhuoshui River alluvial fan, Taiwan, using groundwater level data from 88 wells and stream stage data from 4 gauging stations. In order to accomplish this analysis, wavelet analysis is first carried out to investigate the periodic cycles of groundwater level, precipitation, and stream stage. The results of the analysis show that variations of groundwater level and stream stage are highly correlated in terms of seasonal and annual periods. Subsequently, seasonal variations of groundwater level in response to stream stage variation are utilized to estimate the Ks spatial distribution by spatiotemporal cross correlation analysis, cokriging, and river stage tomography. Prior to applications of these methods to the alluvial fan, performances of each approach are evaluated and compared with reference field of a noise free synthetic experiment. It is found that all of the approaches could yield similar general spatial pattern of Ks. Nevertheless, river stage tomography seems to reveal a higher resolution of spatial Ks distribution. When the geologic zones are provided in river stage tomography analysis as prior information, the accuracy of estimated Ks values improves. Finally, results of the applications to data of the alluvial fan reveal that the apex and southeast of the alluvial fan are regions with relative high Ks and the Ks values gradually decrease toward the shoreline of the fan. These two areas are considered as the possible main recharge regions of the aquifer. It is also observed that Ks at northern alluvial fan is slightly larger than that at southern. These findings seem consistent with the geologic evolution of this alluvial fan.
34
Ermert, Markus. "Electromechanical actuator concept for the controlled and direct actuation of a hydraulic main stage." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-200729.
Full textAbstract:
Hydraulic main stages for off highway machines have usually electromagnetic driven pilot valves. You rarely find stepper motor driven pilot systems that are directly positioning the main spool in the sectional control valve. The presented concept shows the development of an actuator in a unique setup to fulfill the requirements of most off- highway applications. Precise positioning, strength, speed and fail safe requirements were the main goals of the concept. The concept has a two phase BLDC transversal flux motor with a single gear stage transmission. The software and control unit are specially designed for this electric motor setup. On a test bench some results of the first samples reveal the technical potential of this concept. The development of the actuator was done in-house of Thomas Magnete GmbH (mechanical, electronical, and software development).
35
Drha, Vojtěch. "Mechanické zajištění hydraulických zdvihacích systémů pro jevištní techniku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-382048.
Full textAbstract:
The aim of this thesis is to design a mechanical position securing of hydraulic elevating systems for stage technology. The first part includes an overview of present state of elevating systems and their securing solutions. The second part determines technical parameters and design of a chosen solution together with control and design calculations. Final part analyses suggested solution in terms of security.
36
Åkesson, Anna. "Hydraulic- hydromorphologic analysis as an aid for improving peak flow predictions." Licentiate thesis, KTH, Vattendragsteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-25425.
Full textAbstract:
Conventional hydrological compartmental models have been shown to exhibit a high degree of uncertainty for predictions of peak flows, such as the design floods for design of hydropower infrastructure. One reason for these uncertainties is that conventional models are parameterised using statistical methods based on how catchments have responded in the past. Because the rare occurrence of peak flows, these are underrepresented during the periods used for calibration. This implies that the model has to be extrapolated beyond the discharge intervals where it has been calibrated. In this thesis, hydromechanical approaches are used to investigate the properties of stream networks, reflecting mechanisms including stage dependency, damming effects, interactions between tributaries (network effects) and the topography of the stream network. Further, it is investigated how these properties can be incorporated into the streamflow response functions of compartmental hydrological models. The response of the stream network was shown to vary strongly with stage in a non-linear manner, an effect that is commonly not accounted for in model formulation. The non-linearity is particularly linked to the flooding of stream channels and interactions with the flow on flood-plains. An evaluation of the significance of using physically based response functions on discharge predictions in a few sub-catchments in Southern Sweden show improvements (compared to a conventional model) in discharge predictions – particularly when modelling peak discharges. An additional benefit of replacing statistical parameterisation methods with physical parameterisation methods is the possibility of hydrological modelling during non-stationary conditions, such as the ongoing climate change.QC 20101022
37
Carlin, Matthew P. "The Hydraulic Dimension of Reconstruction in Louisiana, 1863-1879." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2594.
Full textAbstract:
Louisiana developed an extensive system of levees throughout the Atchafalaya Basin and along its territorial Mississippi River. This system reached its zenith on the eve of the American Civil War. It went into dramatic decline following the conflict due to the confluence of military activity, protracted irregular warfare, and neglect stemming from labor and capital revolution. These shifts intensified with the 1863 Emancipation Proclamation and finally consolidated after the ratification of Louisiana’s Constitution of 1879. The shift of responsibility for the construction and maintenance of levees during the Reconstruction Era led to many significant changes in the character and function of many of the State’s institutions as it struggled to adapt to the postwar order it confronted.
38
Husovitz, Kari J. "The Influence of Hydraulic Loading Rate on Nitrification Performance in a Two-Stage Biological Aerated Filter Pilot Plant." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/40626.
Full textAbstract:
A two-stage (carbon oxidation stage one, ammonia oxidation stage two) biological aerated filter was operated for 10 months on-site at a domestic wastewater treatment plant. Over the study, the system was operated at different hydraulic loading rates that resulted in a range of applied organic and ammonia mass loadings. Performance was monitored regularly for water quality parameters in the effluent and along the length of the reactors. It was found that nitrification performance was significantly influenced by organic loading rates greater than 1.2 kg cBOD5/m3-d. Additional experiments were conducted in which a constant mass of ammonia was applied (Phase 1: 1.40 ± 0.08 kg NH3-N/m3-d; Phase 2: 1.31 ± 0.02 kg NH3-N/m3-d) to the N column, the second stage of the system, over a range of hydraulic loading rates (5.1 -15.8 m/h). Phases of testing were defined by the background hydraulic loading rate applied to the system (Phase 1: 8.3 m/h; Phase 2: 7.1 m/h) at which the reactors were allowed to reach a steady effluent quality for at least one week prior to testing. Organic loading was minimized and kept relatively constant throughout the hydraulic loading rate experiments (0.65 ± 0.2 kg cBOD5/m3-d) in order to obtain an evaluation of nitrification capacity with minimal competition from heterotrophic bacteria. Results indicated that nitrification performance improved by 17% as the applied velocity increased over the indicated range. A steady-state biofilm model capable of predicting substrate flux was applied to the data in an attempt to explain the improvement in performance with hydraulic loading rate from a fundamental standpoint. Mass transfer coefficients, KL, were derived from the model for conditions in which the experimentally observed flux correlated with the model predictions. Derived KL values were lower than estimations offered by correlation equations but increased with velocity at a similar rate. The model failed to account for changes that may have occurred in biofilm kinetics and structure throughout the length of the reactor.Master of Science
39
Tse, Man Kit. "Influence of stress states on soil-water characteristics, conjunctive surface-subsurface flow modelling and stability analysis /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202007%20TSE.
Full text
40
Simon, James-Eric H. "Urban Hydraulic Rhizome: Water, Space, and the City in 20th Century North Texas." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984269/.
Full textAbstract:
During the modern era, the urbanization of water has been facilitated by various privileged discourses, which valorize major engineering interventions for the sake of continued urban growth. This research examines discourse surrounding the 2-th Century proposal and construction of a reservoir near the then-tiny farming community of Grapevine, Texas, for the benefit of urban interests. I argue that urban interests produced Grapevine space as nothing more than a container for city water, by rendering meaningless any conception of space that was not directly articulated with urban economic networks. Modern discourse collapsed Denton Creek space from a watershed and landscape into a dimensionless node in the urban space of flows. In return, rural inhabitants were encouraged to progress and to modernize their own spaces: to become urban. Whereas urban discourse entails an implicit spatial imaginary of networks, I deploy the conceptual framework of settler colonialism to show that a core-periphery relationship remains relevant, and is not reducible to a network spatial ontology.
41
Kučo, Stanislav. "Posuvná a zvedací plošina." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231665.
Full textAbstract:
This thesis describes a project of a mobile stage device that will be used for a concert tour of Lucie. The first part characterizes the given task and expounds description and function of the device itself. The second part focuses on the design concept of supporting frames. This is followed by design and calculation of all mechanisms, actuators and construction of individual moving parts of a sliding and lifting platform. The last part verifies stability of the whole construction in accordance with appropriate standards. The thesis also contains technical documentation, which is to be found in appendix.
42
Gullhamn, Esbjörn. "Control of Water Content and Retention in Hydropower Plant Cascades." Thesis, KTH, Reglerteknik, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109482.
Full textAbstract:
The discharge through a river hydropower plant must be controlled such that the water level at a pre-specified point close to the facility is kept within given bounds. The controllers used today have a somewhat demanding tuning and often create too much amplified, unnatural discharge variations resulting in unsatisfactory control performance.This will affect both surrounding nature and imposing problems for river navigation. This thesis will present a new type of controller called Override Selector feedback Control that adds an estimator for the water levels and water flows in the up- and downriver for each hydropower plant on top of the old controller. The objective of the state feedback control is to keep the total variation of the water levels and the waterflows as small as possible. After the linear, discrete time model of the power plant cascade in a river derived from the Saint Venant equations have been developed, the new concept is evaluated. Both the water level sloshing and the amplification of the discharges compared to the structure used today is damped with the new control structure. Other advantages of the proposed controller is that it will be cost efficient to implement because of the add-on approach. This is seen as a very important factor while the actual benefit that can be made by improving the water level control is very limited and thereby also the will to make extensive control investments. The control structure will be easily implemented as the estimators only need the same input data as used today.
43
Slabbert, Rohan. "Thermal–hydraulics simulation of a benchmark case for a typical Materials Test Reactor using Flownex / Slabbert R." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7575.
Full textAbstract:
The purpose of this study was to serve as a starting point in gaining understanding and experience of simulating a typical Pool Type Research Reactor with the thermal hydraulic software code Flownex®. During the study the following evaluations of Flownex® were done:
* Assessment of the simplifying assumptions and possible shortcomings built into the software.
* Definition of the applicable modelling methodology and further simplifying assumptions that have to be made by the user.
* Evaluation of the accuracy and compatibility with the Pool Type Research Reactor.
* Comparing the results of this study with similar studies found in the open literature.
For the study the IAEA MTR 10 MW benchmark reactor (IAEA, 1992a) was used. A steady state simulation using Flownex® was done on a single fuel assembly, and this was compared with a model that was developed using the software package EES (Engineering Equation Solver). The results have shown good agreement between the different packages. After this verification, a steady state simulation of the entire core was done to obtain the characteristics of the reactor operating under normal condition. Finally, transient simulations were done on various LOFAs (Loss of Flow Accidents). The results of the various LOFAs were compared with studies that were previously done on the IAEA MTR 10 MW reactor.Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.
44
Gold, Daniel. "Lobbying Regulation in Canada and the United States: Political Influence, Democratic Norms and Charter Rights." Thesis, Université d'Ottawa / University of Ottawa, 2020. http://hdl.handle.net/10393/40908.
Full textAbstract:
Lobbying should be strictly regulated – that is the major finding of this thesis. The thesis presents many reasons to enact stricter regulations. The principle one being that, as lightly regulated as it is, lobbying is corroding democracy in both Canada and the United States.
The thesis opens with a deep investigation of how lobbying works in both countries. There are examples taken from the literature, as well as original qualitative interviews of Canadian lobbyists, former politicians, and officials. Together, these make it clear that there is an intimate relationship between lobbying and campaign financing. The link between the two is sufficiently tight that lobbying and campaign financing should be considered mirrors of each other for the purposes of regulatory design and constitutional jurisprudence. They both have large impacts on government decision-making. Left lightly regulated, lobbying and campaign financing erode the processes of democracy, damage policy-making, and feed an inequality spiral into plutocracy. These have become major challenges of our time.
The thesis examines the lobbying regulations currently in place. It finds the regulatory systems of both countries wanting. Since stricter regulation is required to protect democracy and equality, the thesis considers what constitutional constraints, if any, would stand in the way. This, primarily, is a study of how proposed stronger lobbying regulations would interact with the Canadian Charter of Rights and Freedoms, s. 2 (free expression and association rights) and s. 3 (democratic rights). The principal findings are that legislation which restricted lobbying as proposed would probably be upheld by the Canadian court, but struck down by the American court, due to differences in their constitutional jurisprudence. The thesis contends that robust lobbying regulations would align with Canadian Charter values, provide benefits to democracy, improve government decision-making, increase equality, and create more room for citizen voices.
The thesis concludes with a set of proposed principles for lobbying reform and an evaluation of two specific reforms: limits on business lobbying and funding for citizen groups. Although the thesis focuses on Canadian and American lobbying regulations, its lessons are broadly applicable to any jurisdiction that is considering regulating lobbying.
45
Nguyen, Thanh Don. "Impact de la résolution et de la précision de la topographie sur la modélisation de la dynamique d’invasion d’une crue en plaine inondable." Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0093/document.
Full textAbstract:
Nous analysons dans cette thèse différents aspects associés à la modélisation des écoulements à surface libre en eaux peu profondes (Shallow Water). Nous étudions tout d’abord le système d’équations de Saint-Venant à deux dimensions et leur résolution par la méthode numérique des volumes finis, en portant une attention particulière sur les aspects hyperboliques et conservatifs. Ces schémas permettent de traiter les équilibres stationnaires, les interfaces sec/mouillé et aussi de modéliser des écoulements subcritique, transcritique et supercritique. Nous présentons ensuite la théorie de la méthode d’assimilation variationnelle de données adaptée à ce type d’écoulement. Son application au travers des études de sensibilité est longuement discutée dans le cadre de l'hydraulique à surface libre. Après cette partie à caractère théorique, la partie tests commence par une qualification de l’ensemble des méthodes numériques qui sont implémentées dans le code DassFlow, développé à l’Université de Toulouse, principalement à l’IMT mais aussi à l’IMFT. Ce code résout les équations Shallow Water par une méthode de volumes finis et est validé par comparaison avec les solutions analytiques pour des cas tests classiques. Ces mêmes résultats sont comparés avec un autre code d’hydraulique à surface libre aux éléments finis en deux dimensions, Telemac 2D. Une particularité notable du code DassFlow est de permettre l’assimilation variationnelle de données grâce au code adjoint permettant le calcul du gradient de la fonction coût. Ce code adjoint a été obtenu en utilisant l'outil de différentiation automatique Tapenade (Inria). Nous testons ensuite sur un cas réel, hydrauliquement complexe, différentes qualités de Modèles Numériques de Terrain (MNT) et de bathymétrie du lit d’une rivière. Ces informations proviennent soit d’une base de données classique type IGN, soit d’informations LIDAR à très haute résolution. La comparaison des influences respectives de la bathymétrie, du maillage et du type de code utilisé, sur la dynamique d’inondation est menée très finement. Enfin nous réalisons des études cartographiques de sensibilité aux paramètres du modèle sur DassFlow. Ces cartes montrent l’influence respective des différents paramètres ou de la localisation des points de mesure virtuels. Cette localisation optimale de ces points est nécessaire pour une future assimilation de données efficienteWe analyze in this thesis various aspects associated with the modeling of free surface flows in shallow water approximation. We first study the system of Saint-Venant equations in two dimensions and its resolution with the numerical finite volumes method, focusing in particular on aspects hyperbolic and conservative. These schemes can process stationary equilibria, wetdry interfaces and model subcritical, transcritical and supercritical flows. After, we present the variational data assimilation method theory fitted to this kind of flow. Its application through sensitivity studies is fully discussed in the context of free surface water. After this theoretical part, we test the qualification of numerical methods implemented in the code Dassflow, developed at the University of Toulouse, mainly at l'IMT, but also at IMFT. This code solves the Shallow Water equations by finite volume method and is validated by comparison with analytical solutions for standard test cases. These results are compared with another hydraulic free surface flow code using finite elements in two dimensions: Telemac2D. A significant feature of the Dassflow code is to allow variational data assimilation using the adjoint method for calculating the cost function gradient. The adjoint code was obtained using the automatic differentiation tool Tapenade (INRIA). Then, the test is carried on a real hydraulically complex case using different qualities of Digital Elevation Models (DEM) and bathymetry of the river bed. This information are provided by either a conventional database types IGN or a very high resolution LIDAR information. The comparison of the respective influences of bathymetry, mesh size, kind of code used on the dynamics of flooding is very finely explored. Finally we perform sensitivity mapping studies on parameters of the Dassflow model. These maps show the respective influence of different parameters and of the location of virtual measurement points. This optimal location of these points is necessary for an efficient data assimilation in the future
46
Sattouf, Mousa. "Systém snímání dat a ovládání vodní elektrárny prostřednictvím internetové techniky." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-233685.
Full textAbstract:
Vodní energie se nyní stala nejlepším zdrojem elektrické energie na zemi. Vyrábí se pomocí energie poskytované pohybem nebo pádem vody. Historie dokazuje, že náklady na tuto elektrickou energii zůstávají konstantní v průběhu celého roku. Vzhledem k mnoha výhodám, většina zemí nyní využívá vodní energie jako hlavní zdroj pro výrobu elektrické energie.Nejdůležitější výhodou je, že vodní energie je zelená energie, což znamená, že žádné vzdušné nebo vodní znečišťující látky nejsou vyráběny, také žádné skleníkové plyny jako oxid uhličitý nejsou vyráběny, což činí tento zdroj energie šetrný k životnímu prostředí. A tak brání nebezpečí globálního oteplování. Použití internetové techniky k ovladání několika vodních elektráren má velmi významné výhody, jako snížení provozních nákladů a flexibilitu uspokojení změny poptávky po energii na straně spotřeby. Také velmi efektivně čelí velkým narušením elektrické sítě, jako je například přidání nebo odebrání velké zátěže, a poruch. Na druhou stranu, systém získávání dat poskytuje velmi užitečné informace pro typické i vědecké analýzy, jako jsou ekonomické náklady, predikce poruchy systémů, predikce poptávky, plány údržby, systémů pro podporu rozhodování a mnoho dalších výhod. Tato práce popisuje všeobecný model, který může být použit k simulaci pro sběr dat a kontrolní systémy pro vodní elektrárny v prostředí Matlab / Simulink a TrueTime Simulink knihovnu. Uvažovaná elektrárna sestává z vodní turbíny připojené k synchronnímu generátoru s budicí soustavou, generátor je připojen k veřejné elektrické síti. Simulací vodní turbíny a synchronního generátoru lze provést pomocí různých simulačních nástrojů. V této práci je upřednostňován SIMULINK / MATLAB před jinými nástroji k modelování dynamik vodní turbíny a synchronního stroje. Program s prostředím MATLAB SIMULINK využívá k řešení schematický model vodní elektrárny sestavený ze základních funkčních bloků. Tento přístup je pedagogicky lepší než komplikované kódy jiných softwarových programů. Knihovna programu Simulink obsahuje funkční bloky, které mohou být spojovány, upravovány a modelovány. K vytvoření a simulování internetových a Real Time systémů je možné použít bud‘ knihovnu simulinku Real-Time nebo TRUETIME, v práci byla použita knihovna TRUETIME.
47
Bardet, Romaric. "Approvisionnement en eau et gestion de la ressource en milieu urbain : le cas des cités-états grecques de Crète (VIIIe s.-67 av. J.-C.)." Thesis, Paris 4, 2016. http://www.theses.fr/2016PA040193.
Full textAbstract:
L’approvisionnement en eau et la gestion de cette ressource dans les centres urbains des cités grecques de Crète est un sujet de recherche récent, qui pose la question de l’efficacité de la civilisation hydraulique crétoise du Ier millénaire av. J.-C. dans son ensemble. Empruntant aux sciences de la nature, à la géographie ainsi qu’à l’histoire, l’étude entend replacer l’archéologie au cœur du débat, pour illustrer en particulier la contribution des techniques hydrauliques crétoises au développement des concentrations urbaines nouvelles qu’induisit l’apparition, puis l’épanouissement des cités-États dans l’île entre le VIIIe s. av. J.-C. et la conquête de l’île par Rome, en 67 av. J.-C. Il apparaît que la plupart des formes de réponse actuelles aux enjeux de l’approvisionnement en eau des villes étaient connues en Crète dès l’âge du FerThe water supply and the management of this resource in the urban areas of the Greek cities of Crete is a recent research theme, which raises the question of the efficiency of the Cretan hydraulic civilization of the first millenium B.C. in general. Borrowing from the sciences of the nature, from the geography, as well as from the history, the study intends to put the archaeology back in the heart of the debate, to illustrate in particular the contribution of the Cretan hydraulic techniques to the development of the new conurbations led by the emergence, and then the blooming of city-states on the island between the eigth century B.C. and the conquest of the island by Rome, in 67 B.C. It seems that most of the current forms of answer to water supply issues of cities were known in Crete from the Iron Age
48
Schlothmann, Daniel. "Kurz- und langfristige Angebotskurven für Rohöl und die Konsequenzen für den Markt." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-201396.
Full textAbstract:
In dieser Arbeit wurden Angebotskurven für 22 bedeutende Ölförderländer ermittelt und anschließend zu globalen Angebotskurven aggregiert. Gemäß den ermittelten Angebotskurven sind nahezu alle gegenwärtig in der Förderphase befindlichen Ölprojekte in den Untersuchungsländern auch beim aktuellen Ölpreis von 35 bis 40 US-$ je Barrel unter Berücksichtigung der kurzfristigen Grenzkosten rentabel. Sollte der Ölpreis jedoch in den kommenden Jahren auf diesem Niveau verharren, wird es bis zum Jahr 2024 zu einem Angebotsengpass auf dem globalen Ölmarkt kommen, da zur Deckung der zukünftigen Nachfrage die Erschließung kostenintensiver, unkonventioneller Lagerstätten und von Lagerstätten in tiefen und sehr tiefen Gewässern notwendig ist. Damit es bis zum Jahr 2024 nicht zu einem solchen Angebotsengpass kommt, ist gemäß des ermittelten langfristigen Marktgleichgewichts ein Ölpreis von mindestens 80 (2014er) US-$ je Barrel notwendig.
49
Perkins, Adam Reed. "An examination of state regulations of hydraulic fracturing." Thesis, 2014. http://hdl.handle.net/2152/26531.
Full textAbstract:
As hydraulic fracturing gains popularity in the energy industry, the state of Texas finds itself in a very advantageous position. With multiple regions which could have great potential for oil and natural gas extractable via the production technique, Texas has assumed a new importance for the energy industry. However, in order to fully utilize its advantages, the state of Texas should revise its oil and gas regulations, particularly with regard to groundwater use and contamination, air emissions, and discretion for municipal regulation of oil and gas operations, insofar as they may apply to hydraulic fracturing. This course of action only will this allow the state to efficiently utilize the production method while better balancing against the technique's risks.text
50
Lin, Chang-Yun, and 林常昀. "Study on State Parameter of Hydraulic Filled Sand." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/25866885833869941007.
Full text