Dissertations / Theses on the topic 'Lumped and Distributed-Lumped modelling'
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Oh, Min. "Modelling and simulation of combined lumped and distributed processes." Thesis, Imperial College London, 1995. http://hdl.handle.net/10044/1/8197.
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Mejuto, Carlos. "Improved lumped parameter thermal modelling of synchronous generators." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4612.
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Within the existing available mix of numerical and analytical thermal analysis options, lumped parameter thermal modelling is selected as the operational backbone to develop an improved novel synchronous generator thermal modelling package. The objective is for the creation of a user friendly quick feedback tool, which can serve as a means to make quick machine design thermal calculations and answer customer queries quickly and reliably. Furthermore, thermally improved generator designs will allow for inevitable operational losses to be channelled away from the machine more efficiently. As a result, machine component temperatures will be reduced, allowing lower generator thermal ratings. The end result will be smaller, longer lasting, more efficient generators, with the ability to be adapted with greater ease to particular applications. With the contribution of selected numerical analysis techniques, mainly finite element analysis for the distribution of iron losses, the MySolver thermal modelling package is developed and presented in this thesis. It is this combination of numerical and analytical tools that improves synchronous generator thermal modelling accuracy, but ultimately it is the lumped parameter nature of the thermal models developed that makes MySolver succeed as a reliable quick feedback electrical machine thermal design tool, validated using experimental results for a wide range of operating conditions. The initial part of the thesis analyses the electrical machine thermal modelling techniques available today, indicating advantages and disadvantages associated with each one, and providing a rationale for the selection of lumped parameter modelling to be used by MySolver. The development of the synchronous generator lumped parameter thermal models is detailed, with examples on its construction presented. Subsequently, finite element analysis is utilised to predict the distribution of machine iron losses across the rotor and stator laminations, with the findings applied to MySolver. Furthermore, a study is performed into the lumped parameter discretisation level needed to effectively represent machine windings. MySolver is experimentally verified using experimental data from a fully instrumented synchronous generator and this data is also used to obtain further insight into the temperature distribution within the generator. In the final part results are evaluated and the use of MySolver for modelling and optimising electrical machines is discussed. Finally, appropriate conclusions on the work presented are drawn.
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Grobler, Andries Johannes. "Thermal modelling of a high speed permanent magnet synchronous machine / Andries J. Grobler." Thesis, North-West University, 2011. http://hdl.handle.net/10394/6528.
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Thermal modelling is of great importance in all electric machines but especially in permanent
magnet synchronous machines (PMSMs). The thermally fragile permanent magnets (PMs) can
more easily be demagnetized at high temperatures. When high speed machines are considered,
heat extraction surfaces are small due to the higher energy density. This thesis focuses on the
thermal modelling of a high speed slotless PMSM using analytical techniques. From literature
it is clear that analytical distributed models have not reached its full potential in thermal modelling
of electric machines. Thermal experiments on high speed electric machine, including
rotor PM temperature measurements are not commonly found in literature.
The thermal behaviour of each component of the machine is influenced by the overall temperature
distribution. The widely used lumped parameter (LP) cylindrical component model
derived by Mellor et al. is used to derive a LP model of the entire machine. A two dimensional
(2-D) analytical distributed model is derived for the rotor PM using the separation of variables
method. Three of the boundaries are assumed to be of the convection type and the fourth of
constant heat flow type. Different convection coefficients are assumed to exist in the radial and
axial directions. The distributed model is verified using COMSOL
R and good correlation is
shown. The distributed model is used to determine the temperature distribution in the PM
and the convection heat flow in the axial direction.
Loss calculation is an integral part of thermal modelling. Temperature changes in an electric
machine is due to the interaction between the heat generation (losses) and heat removal. The
losses found in a high speed slotless PMSM are investigated. A 2-D analytical magnetic model
is used to determine the stator lamination loss as well as the stator winding eddy current loss. A
simple LP model is derived for the rotor eddy current loss. Due to the relatively large resistivity
of the shielding cylinder and PM material, the rotor eddy current loss is a significant part of the
total machine loss. The tangential current width is determined empirically in this thesis but a
3-D distributed model which includes end space effects and skin depth could also be used.
A large part of thermal modelling is empirically based. The convection and interface resistances
are determined through a set of experiments in this thesis. The measured and calculated
convection coefficients correlated well for both forced and natural convection cooling. A large
temperature increase found during the no-load test can be attributed to large bearing loss, possibly
due to axial loading. The LP model is modified to include the phenomena found during
the experiments.
The thermal model is used to predict the temperatures of a high speed PMSM at rated load and speed. Although the PM is not heated above the Curie temperature, demagnetization is
still possible. According to the model, the machine will not be able to operate at full load and
speed for extensive periods due to mechanical stress limits being exceeded. The temperature
distribution of the PM could not be verified since the temperatures in the air gap and end space
could not be measured. It is expected that axial heat flow will be larger than what is currently
predicted by the distributed model. A sensitivity analysis was used to investigate the influence
of the thermal resistances and losses on the machine temperatures. Methods for reducing the
rotor eddy current loss and interface resistances are also discussed.
The first contribution of this thesis is the 2-D analytical distributed model for the PM of a high
speed PMSM. Hot spots and 2-D heat flow can be analysed using this model. Combining the
LP and 2-D analytical distributed models is another contribution. This combines the simplicity
and fast solution times of the LP model with the 2-D thermal distribution of the analytical
distributed model. The systematic experimental investigation of the thermal behaviour of a
high speed PMSM is a further contribution.Thesis (Ph.D. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Alkaragoolee, Mohammed Y. A. "Hybrid Modelling and Optimisation of Oil Well Drillstrings." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/16859.
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The failure of oil well drillstrings due to torsional and longitudinal stresses
caused by stick-slip phenomena during the drilling operation causes great
expense to industry. Due to the complicated and harsh drilling environment,
modelling of the drillstring becomes an essential requirement in studies.
Currently, this is achieved by modelling the drillstring as a torsional lumped
model (which ignores the length of the drillstring) for real-time measurement
and control. In this thesis, a distributed-lumped model including the effects of
drillstring length was developed to represent the drillstring, and was used to
simulate stick-slip vibration. The model was developed with increasing levels of
detail and the resultant models were validated against typical measured signals
from the published literature.
The stick-slip model describes the friction model that exists between the cutting
tool and the rock. Based on theoretical analysis and mathematical formulation
an efficient and adaptable model was created which was then used in the
application of a method of species conserving genetic algorithm (SCGA) to
optimise the drilling parameters.
In conclusion, it was shown that the distributed-lumped model showed improved
detail in predicting the transient response and demonstrated the importance of
including the drillstring length. Predicting the response of different parameters
along the drillstring is now possible and this showed the significant effect of
modelling the drillcollar. The model was shown to better represent real system
and was therefore far more suited to use with real time measurements.Iraqi Government, Ministry of Higher Education and Scientific Research.
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Dimitriou, Vanda. "Lumped parameter thermal modelling for UK domestic buildings based on measured operational data." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/23239.
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The development and use of thermal models is an integral part of the design process in existing buildings due for refurbishment. Energy predictions for existing buildings are often based on models which assume thermal property values of the building construction elements. However, once built, the actual thermal properties may differ significantly from their estimated values. Possible reasons include thermal bridging, material distortion and moisture content, sub-standard construction on-site and unavailability of construction details. The uncertainties can be reduced if the modelling process can also make use of operational measurements, such as the fuel use and internal temperatures, which have been recorded in the building during operation. To make use of operational data, performance-based models can be used. Performance-based models rely on measured data for the development of the model s architecture and for informing the estimation of the model parameters that would otherwise be based on the modeller s assumptions of the building s characteristics. One solution to the challenge of using performance-based models for existing buildings is to use the Lumped Parameter modelling approach. The Lumped Parameter modelling technique is often used for performance-based modelling of existing buildings due to the moderate knowledge of the building s physical properties required and the limited operational data needed for model training. This thesis investigates the potential of performance-based modelling techniques for existing UK domestic buildings, based on the Lumped Parameter thermal modelling technique, and the use of measured operational data to inform the model structure and parameters. Operational data have been collected in 20 homes as part of the REFIT project, an EPSRC-funded research project on Smart Meters and Smart Homes (REFIT, 2016). This thesis explores 11 houses from the REFIT dataset and, in particular, the temperature, gas and electricity measurements from the participating households, and develops whole-house and sub-system performance-based models using the Lumped Parameter technique. The suitability of simple performance-based Lumped Parameter models in representing typical UK domestic buildings using mainstream operational data such as temperatures and gas consumption measurements is explored. This thesis concludes on the adequacy of the operational data as measured. High correlations (>0.9) between whole-house average indoor temperatures and individual room air temperature measurements prove the use of averages adequate for representing the main rooms of the houses, whereas individual representation of the house s main rooms in use in the same model can prove challenging. A similar result is observed for whole-house radiator representation and the individual radiators. The relationships between the operational data is explored to inform the model structure and to identify collinearity and multi collinearity in the measurements. In terms of whole-house modelling, when using constraints for the parameter values during the model calibration to the measured data the resulting model parameters can be realistic and a good agreement to the measured data can be achieved (on average an RMSE of 1.03 for air temperature). The most significant parameters affecting the mean value of internal air temperatures are the external envelope resistance Re, the non-inertia elements (e.g. windows and doors) resistance, the window area for solar gains, boiler efficiency and the infiltration rate. The indoor air and internal element heat capacitance had the greatest impact on the swing in the internal air temperature (a 75% decrease in the capacitance value resulted in a 190.70% increase in the standard deviation value on average across the 11 houses). The building envelope heat capacitance and the envelope node positioning were the two parameters with the least impact on the model goodness of fit (a 75% decrease in capacitance and a value of 0.9 in envelope node positioning resulted in a 2.57% and 6.68% increase respectively in the RMSE on average across all 11 houses). Finally, the heating system representation using the Lumped Parameter model showed that the whole-house gas consumption data at the meter level, consisting of gas used for space heating as well as other purposes, is inadequate to drive the heating system model. A temperature threshold (e.g. of 1oC) indicating model overprediction can be used to remove the time-stamps of mixed use gas consumption from the model calibration. The heating system model can then be used to quantify gas consumption for space heating and non-space heating uses. In the 11 houses under study, 82.96% of the total gas consumption served for space heating, with 17.04% serving for other non-space heating purposes.
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Shi, Yubing. "Lumped-parameter modelling of cardiovascular system dynamics under different healthy and diseased conditions." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/4198/.
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Cardiovascular disease is the most common cause of death in the modern society, and research into the diagnosis and treatment of cardiovascular diseases is an urgent task. Lumped-parameter mathematical modelling as an efficient and effective research technique has been extensively applied in the cardiovascular dynamics research, and has achieved enormous success in assisting the cardiovascular physiology study. This thesis reports a coherent work of lumped-parameter cardiovascular modelling based on some selected works that the author has conducted and published in the past several years. After a critical and comprehensive review of the concurrent lumped-parameter modelling technique, an improved lumped-parameter model that effectively describes the important cardiovascular features of heart valve dynamics and atrial-ventricular septum motion is presented. The model is then adapted to study several application cases of typical heart failure condition with ventricular assist device support, and extension of the lumped-parameter modelling for the optimisation of a pulsatile bioreactor in cardiovascular tissue engineering study. Some on-going works and future directions are also introduced. The reported modelling studies are useful for the cardiovascular physiology research and design optimisation of cardiovascular prosthetic organs.
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Siushansian, R. "Finite-volume time-domain modelling of complex geometries and lumped elements in generalised coordinate systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0020/NQ58191.pdf.
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Zhang, Shilong. "Lumped-parameter modelling of elastically coupled bodies: Derivation of constitutive equations and determination of stiffness matrices." Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/284462.
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Modelling of elastically coupled rigid bodies is an important research topic in multibody dynamics. We consider the problem of modelling what can be called flexural joints, where two essentially rigid bodies are coupled by a substantially more elastic body. For modelling general elastic couplings one would like to have generically applicable, lumped parameter, intuitive, Euclidean geometric, accurate models with desirable physical symmetries. The model constitutive equations should be easily and quickly computable. For purely elastic coupling the constitutive equations should be truly energy conservative: the configuration-wrench equations should be derivable from a potential function. Linear and angular momentum should be conserved. Quaternion-based and twist-based modelling methods are presented. The constitutive equations to calculate the configuration-wrench behavior are derived via geometric potential energy functions. Wrenches are computable given the configurations of the rigid bodies and all the stiffness matrices of the compliant element. For an arbitrary pair of elastically coupled rigid bodies there exist coincident, unique points on the bodies known as centers of stiffness at which translation and rotation are minimally coupled. At the center of stiffness there exist three sets of orthonormal principal axes and corresponding principal stiffnesses. These parameters are useful in both analysis and numerical simulation. A finite-element-based method for computing canonical stiffness parameters of elastically coupled rigid bodies is presented. The method is applied to notch hinges and Remote Center of Compliance (RCC) hinges. Standard procedures are presented on how to determine canonical stiffness parameters at the center of stiffness of a spatial compliance. Series of canonical stiffness parameters can be generated automatically using the methods provided. Key program listings are provided which can be used to duplicate the results presented.
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Mkadara, Geneviève, and Jean-Charles Maré. "Development of a lumped parameter model of an aerospace pump for condition monitoring purposes." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71205.
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This paper presents the development of a helicopter axial piston pump model with condition monitoring in mind. Industrial constraints and needs ask for modelling with a lumped-parameter approach and require model architecture to be addressed with care. The aim of the proposed model is to assess the merits of pump leakage monitoring through measurement of case pressure. Once reviewed the state of the art in pump modelling, the slipper/swashplate interface is taken as an example to propose and implement in Simcenter AMESim a variable gap height model. The simulation results show that commonly used lumped-parameter models overestimate leakage. It also points out that average leakage at slipper may reverse at high pump displacement.
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Ring, Emma. "Modelling a piezoelectric-driven actuator for active flow control." Thesis, Linköpings universitet, Reglerteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-114957.
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Flow control is an area of research of particular interest within automotive and aerospace industries since methods used to affect the fluid flow around vehicles can reduce drag and therefore lower their fuel consumption. One of these methods, which has generated a lot of interest in later years, is called active flow control and uses different types of actuators to impact the surrounding flow. In this thesis a model of a piezoelectric actuator for active flow control has been developed using Lumped Element Modelling and equivalent circuits. This approach, together with the chosen software for implementation, Simulink, provides models which are easy to simulate and evaluate. The actuator model has been validated using a novel methodology with sub-models with the purpose of reducing computational costs. The actuator is therefore divided into two submodels,one for structural and one for fluid dynamics, which are validated separately. This enables the use of simple yet accurate FEM and CFD models instead of time consuming FSI software which the complete model requires. The three implemented models have been validated using cases presented in previous studies and data from CFD-simulations. The results show that the decoupled models can be validated separately and its results can be integrated into the complete model, although further tests with a real actuator is needed. In addition to the modelling, a parameter study of the actuator has been performed in order to prepare for prototype design.
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Filippou, Sotirios. "Virtual sensor for air mass flow measurement in an SI engine: Application of distributed lumped modelling in prediction of air mass flow into the cylinder of SI combustion engines." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17450.
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After undergoing an extensive study about engine air mass flow measurement approaches as well as engine modelling for air mass flow prediction, a major problem found to exist is that engineers have still not found a suitable technique to accurately measure the air mass flow entering the cylinder of an internal combustion engine. The engine air mass flow is the most important parameter needed during engine development so the fuel control can be accurately calibrated and as a result increase performance and reduce emission output of an engine. The current methods used to determine the air mass flow lead to inaccuracies due to the large amount of mathematical assumptions and also sensor errors and as a result the mapping and calibration process of a new engine family takes approximately 2 years due to extensive modelling and testing required overcoming the above drawbacks. To improve this, the distributed lumped modelling technique (D-L) of the inlet manifold was chosen, where the intake system is separated into very small sections which are distributed continuously throughout the volume of the intake until entering the cylinder. This technique is validated against a CFD model of the engine’s intake system and real engine data as well as a 1D engine model.
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Svensson, Oskar. "Electrohydraulic Power Steering Simulation : Dynamic, thermal and hydraulic modelling." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265674.
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There are several benets of electrohydraulic power steering systems, as compared to hydraulicpower steering systems where the pump is driven directly by the engine of the vehicle. Someof these benets are increased eciency and improved steering performance. The purpose ofthis project is to create a simulation model of the electrohydraulic power steering system inSimulink, excluding the hydraulic circuit. The model should thus consist of the electric motor,the drive electronics, the control system, the hydraulic pump as well as the communication andinterface to the master simulation system in which the model will be used.As a start a mathematical model of the motor is derived. Then the motor controller includingtwo current controllers and a speed controller is developed. The switching signals for the threephase bridge that drives the motor are calculated using space vector modulation. The motordrives a hydraulic pump, which is modeled using data sheet eciency curves. Finally a thermalmodel of the drive is developed. To fulll real time requirements, a lumped parameter approachis chosen. The nal model is exported as a Functional Mock-up Unit, which is a black-boxencapsulation of the complete simulation model.The simulation model is compared to measurement data to conrm its validity. Thesecomparisons shows that the dynamic response of the motor and its controller are close to themeasured values and that the thermal model adequately corresponds to the thermal tests. Thehydraulic pump model varied from measurements more than the other sub-modules. It was,however, seen as acceptable. Overall the system response was satisfactory, but naturally a lotof future improvements and new features could be made to improve the model.Det finns flera fördelar med elektrohydraulisk servostyrning, där hydraulpumpen drivs av en el-motor, jämfört med hydraulisk servostyrning, där pumpen drivs direkt av fordonets förbränningsmotor. Några av dessa fördelar är ökad effektivitet och förbättrad styrprestanda. Syftet med detta projekt är att skapa en Simulink-modell av ett elektrohydraulisk system för servostyrning, exklusive hydraulkretsen. Modellen ska alltså bestå av delmodeller för elmotorn, drivelektroniken, styrsystemet, hydraulpumpen samt kommunikation med den övergripande simuleringsplattformen.Inledningsvis beskrivs en matematisk modell av elmotorn och efter det utvecklas motorstyrningen, bestående av två strömregulatorer samt en hastighetsregulator. Spänningen från strömregulatorerna uppnås genom space vector-modulation, som beräknar de pulskvoter som krävs för att uppnå denna spänning. Elmotorn driver en pump. Denna pump modelleras med hjälp av data från pumpens datablad. Slutligen modelleras drivelektronikens termiska egenskaper med ett termiskt nätverk. Den slutliga modellen omsluts av en Functional Mock-up Unit somintegreras i den övergripande simuleringsplattformen.
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Holmberg, Pär. "Modelling the transient response of windings, laminated steel coresand electromagnetic power devices by means of lumped circuits : With special reference to windings with a coaxial insulation system." Doctoral thesis, Uppsala University, Department of High Voltage Research, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-548.
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Electromagnetic transients impinging on electromagnetic power devices - such as electric machines, transformers and reactors - can stress the design severely. Thus the magnitudes of the transients are often decisive for the design of the devices. Further, the operation of a device can be transient in itself. This is the case for the explosive magnetic flux compression generator (EMG) and a ferromagnetic actuator.
Models are presented that are mainly intended for transients in the millisecond range and faster. Hence, eddy currents and the related skin and proximity effect become significant in windings, magnetic cores and in the armatures of the devices. These effects are important for, e.g., the damping of the transients. Further, the displacement current in the insulation of the winding is significant. It changes the response of the windings dramatically, as it manifests the finite velocity of propagation of the electromagnetic fields. Under such circumstances, reflections and excited resonances can make the transient voltage and current distribution highly irregular.
Induced voltages are modelled with self and mutual inductances or reluctances combined with winding templates. The displacement currents are modelled with capacitances or coefficients of potential. Cauer circuits and their dual form are used to model eddy currents in laminated cores and in conductors. The Cauer circuit enables one to consider hysteresis and the non-linear response of a magnetic core. It is also used to model the eddy currents in the moving armature of an EMG.
A set-up is presented that can be used to study the transient voltage and the current distribution along a coil.
The transient response of coaxially insulated windings is analysed and modelled in detail. A lumped circuit model is developed for a coil, DryformerTM - the new high-voltage transformer - and PowerformerTM, the new high-voltage generator. An alternative model, a combined lumped circuit and FEM model, is presented for a coaxially insulated winding in two slot cores.
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Holmberg, Pär. "Modelling the transient response of windings, laminated steel cores and electromagnetic power devices by means of lumped circuits : with special reference to windings with a coaxial insulation system /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2000. http://publications.uu.se/theses/91-554-4877-1/.
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Lakhanpal, Chetan. "Mathematical modelling of applied heat transfer in temperature sensitive packaging systems. Design, development and validation of a heat transfer model using lumped system approach that predicts the performance of cold chain packaging systems under dynamically changing environmental thermal conditions." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/5776.
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Development of temperature controlled packaging (TCP) systems involves a significant lead-time and cost as a result of the large number of tests that are carried out to understand system performance in different internal and external conditions.
This MPhil project aims at solving this problem through the development of a transient spreadsheet based model using lumped system approach that predicts the performance of packaging systems under a wide range of internal configurations and dynamically changing environmental thermal conditions.
Experimental tests are conducted with the aim of validating the predictive model. Testing includes monitoring system temperature in a wide range of internal configurations and external thermal environments.
A good comparison is seen between experimental and model predicted results; increasing the mass of the chilled phase change material (PCM) in a system reduces the damping in product performance thereby reducing the product fluctuations or amplitude of the product performance curve. Results show that the thermal mathematical model predicts duration to failure within an accuracy of +/- 15% for all conditions considered.
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Inalpolat, Murat. "Determination Of Vibroacoustical Behavior Of Plates By Intensity Methods." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605095/index.pdf.
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In this study, sound radiation and power flow characteristics of plates which constitute the bodies of common engineering applications like cars and household appliances are investigated. Three different vibro-acoustical measurement techniques are used in an integrated manner and results obtained are compared with those obtained from analytical models developed.
Two-microphone sound intensity measurement with a probe utilizing side-by-side configuration is used to analyze the near-field radiation characteristics of a square steel plate excited by a shaker at its midpoint. Surface intensity is simultaneously measured on the plate with another probe consisting of a condenser microphone and an eddy-current non-contact displacement transducer to compare the results with those obtained from two-microphone sound intensity measurement. Surface intensity is also measured with a probe consisting of a condenser microphone and an accelerometer as an alternative configuration. Structural intensity is used to identify the power flow patterns on the plate. All measurements are repeated for externally damped configuration of the same plate and results are analyzed. Easily adoptable two distinct, lumped parameter models of the plate are developed to compute the sound power radiated by the structure. In these models, the plate is modeled by employing the pulsating sphere and vibrating piston as the elementary source types, alternatively. In the model employing vibrating piston in the baffle, results are obtained with and without mutual interaction among partitions. Results obtained from these models are compared with the experimental results. Error analysis is also conducted for all of the measurement techniques employed.
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John, Yakubu M. "Kinetic modelling simulation and optimal operation of fluid catalytic cracking of crude oil: Hydrodynamic investigation of riser gas phase compressibility factor, kinetic parameter estimation strategy and optimal yields of propylene, diesel and gasoline in fluid catalytic cracking unit." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17323.
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The Fluidized Catalytic Cracking (FCC) is known for its ability to convert refinery wastes into useful fuels such as gasoline, diesel and some lighter products such as ethylene and propylene, which are major building blocks for the polyethylene and polypropylene production. It is the most important unit of the refinery. However, changes in quality, nature of crude oil blends feedstock, environmental changes and the desire to obtain higher profitability, lead to many alternative operating conditions of the FCC riser.
There are two major reactors in the FCC unit: the riser and the regenerator. The production objective of the riser is the maximisation of gasoline and diesel, but it can also be used to maximise products like propylene, butylene etc. For the regenerator, it is for regeneration of spent or deactivated catalyst.
To realise these objectives, mathematical models of the riser, disengage-stripping section, cyclones and regenerator were adopted from the literature and modified, and then used on the gPROMS model builder platform to make a virtual form of the FCC unit. A new parameter estimation technique was developed in this research and used to estimate new kinetic parameters for a new six lumps kinetic model based on an industrial unit. Research outputs have resulted in the following major products’ yields: gasoline (plant; 47.31 wt% and simulation; 48.63 wt%) and diesel (plant; 18.57 wt% and simulation; 18.42 wt%) and this readily validates the new estimation methodology as well as the kinetic parameters estimated. The same methodology was used to estimate kinetic parameters for a new kinetic reaction scheme that considered propylene as a single lump. The yield of propylene was found to be 4.59 wt%, which is consistent with published data.
For the first time, a Z-factor correlation analysis was used in the riser simulation to improve the hydrodynamics. It was found that different Z factor correlations predicted different riser operating pressures (90 – 279 kPa) and temperatures as well as the riser products. The Z factor correlation of Heidaryan et al. (2010a) was found to represent the condition of the riser, and depending on the catalyst-to-oil ratio, this ranges from 1.06 at the inlet of the riser to 0.92 at the exit.
Optimisation was carried out to maximise gasoline, propylene in the riser and minimise CO2 in the regenerator. An increase of 4.51% gasoline, 8.93 wt.% increase in propylene as a single lump and 5.24 % reduction of carbon dioxide emission were achieved. Finally, varying the riser diameter was found to have very little effect on the yields of the riser products.
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Kolhatkar, Tanmay. "Nonlinear dynamic interactions between a rigid attachment bolted to a thin-walled sheet metal structure." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587124580918153.
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Bek, Jeremy. "Design, simulation, and testing of an electric propulsion cluster frame." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300970.
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In general, electric propulsion offers very high efficiency but relatively low thrust. To remedy this, several ion engines can be assembled in a clustered configuration and operated in parallel. This requires the careful design of a frame to accommodate the individual propulsion systems. This frame must be modular to be used in different cluster sizes, and verify thermal and mechanical requirements to ensure the nominal operation of the thrusters. The present report aims to show the design process of such a frame, from preliminary modelling to the experimental study of a prototype. This document features an overview of the iterative design process driven by thermal simulations rendered on COMSOL Multiphysics. This process led to the conception of a 2-thruster and 4-thruster cluster frame. A lumped-parameter model of the electric propulsion system was also created to model its complex thermal behaviour. In addition, the 2-thruster frame was studied mechanically with analytical calculations and simulations of simple load cases on SolidWorks. Lastly, a prototype based on the 2-thruster frame model was assembled. The prototype was used to conduct temperature measurements while hosting two operating thrusters inside a vacuum chamber. The temperature distribution in the cluster was measured, and compared to simulation results. Thermal simulations of the 2-thruster and 4-thruster frame showed promising results, while mechanical simulations of the 2-thruster version met all requirements. Moreover, experimental results largely agreed with thermal simulations of the prototype. Finally, the lumped-element model proved instrumental in calibrating the models, with its high flexibility and quick computation time.Generellt erbjuder elektrisk framdrivning hög verkningsgrad men relativt låg dragkraft. För att avhjälpa detta kan flera jonmotorer sättas samman i en klusterkonfiguration och drivs parallellt. Detta kräver en noggrann utformning av en ram för att rymma de enskilda framdrivningssystemen. Denna ram måste vara modulär för att kunna användas i olika klusterstorlekar och verifiera termiska och mekaniska krav för att säkerställa den nominella driften av motorerna. Föreliggande rapport syftar till att visa designprocessen för en sådan ram, från preliminär modellering till experimentell studie av en prototyp. Detta dokument innehåller en översikt över den iterativa designprocessen, driven av termiska simuleringar gjorda med COMSOL Multiphysics, som ledde till uppfattningen av en 2 motorer och 4 motorer ram. En klumpelementmodell av jonmotorn skapades också för att modellera dess komplexa termiska beteende. Dessutom var den 2 motorer ram studeras mekaniskt med analytiska beräkningar och simuleringar av enkla laddafall med SolidWorks. Slutligen monterades en prototyp baserad på den 2 motorer rammodellen. Prototypen användes för att göra temperaturmätningar medan den är värd för 2 jonmotorer i en vakuumkammare. Temperaturfördelningen i klustret mättes och jämfördes med simuleringsresultat. Termiska simuleringar av den 2 motorer och 4 motorer ramen visade lovande resultat, medan mekaniska simuleringar av den 2 motorer versionen klarade alla krav. Dessutom överensstämde experimentella resultat till stor del med termiska simuleringar av prototypen. Slutligen var klumpelementmodellen mycket användbar för att kalibrera de andra modellerna med sin höga flexibilitet och snabba beräkningstid.
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Orellana, Bobadilla Barbara A. "Identification of lumped and semi-distributed conceptual rainfall runoff models." Thesis, Imperial College London, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590036.
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Conceptual rainfall runoff (CRR) models usually require calibration to identify their parameter values, whereas their model structure is selected prior to modelling. Consid- erable efforts have been directed into calibration of lumped CRR models. Identification of the model structure on the basis of available data still remains unclear. The data-based mechanistic (DBM) approach does minimal assumptions of the model structure, which is identified using powerful statistic techniques. Moreover, there is a similarity between the CRR and DBM model.formulations. Based on this similarity, an integration of CRR and DBM models is proposed and evaluated. Two calibration strategies are investigated in the Upper Illinois river catchment (USA) for lumped modelling. Results show that the identi- fied TF model improves the simulated flow, especially in the time to peak, in comparison to the modelled flow of the conceptual model. It is suggested that this improvement is di- rectly related to the lag time parameter considered in the TF model between the effective rainfall and the flow. Semi-distributed rainfall runoff models provide advantages over lumped models in representing the effect of spatially variable inputs, outputs and catchment properties. However they are affected by parameter identifiability. Four calibration strategies are considered to analyse the ability to meaningful simulate flow at interior locations. Results show that there are no significant improvements at the catchment outlet when internal gauges are included. The behavioural parameter sets defined at the catchment outlet tend to be non-behavioural at the internal gauges. This tendency increases with the distance from the catchment outlet to the internal gauges. Considering only spatial variability of rainfall rather than also of parameter values did not improve the simulations at the out- let or at the internal gauges, compared to lumped modelling results. Calibration only at the catchment outlet using independent sampling of the internal subcatchments achieved similar results. Identification of lumped and semi-distributed CRR models is carried out using the RRTMSD modelling toolbox developed for this work.
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VENTURINI, VIRGINIA. "A NEW METHODOLOGY TO INTEGRATE PARAMETERS IN LUMPED MODELS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1006882648.
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Laoubi, Yanis. "Modélisation des machines électriques par les réseaux de perméances génériques : cas des machines à flux axial." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMLH17.
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Le travail présenté dans ce mémoire traite de la problématique du dimensionnement de structures innovantes de génératrices, à savoir les machines à flux axial ou encore discoïdes, destinées aux éoliennes de grande puissance allant jusqu'à deux dizaines de mégawatts. Les machines synchrones à aimants permanents à flux axial étant intrinsèquement tridimensionnelles, l'optimisation de leur dimensionnement nécessite un modèle dimensionnant tridimensionnel et multiphysique qui peut être, de par sa nature 3D, très consommateur en mémoire et en temps de calcul. On se propose donc, dans ce mémoire, de développer une approche de modélisation par constantes localisées offrant un très bon rapport entre vitesse de calcul et précision afin d'accélérer de façon significative les premières phases de la procédure de dimensionnement. L'approche par constantes localisées peut par ailleurs s'appliquer de manière similaire aux principales physiques concernées (magnétique, thermique et mécanique). Plus particulièrement pour la partie magnétique, l'approche par constantes localisées est mise en œuvre par le biais de réseaux réluctants magnétiques génériques. Le principe de la méthode développée repose sur le découpage de la géométrie de la machine en volumes élémentaires finis parallélépipédiques à l'instar de qui est fait avec la méthode des éléments finis. En effet, chaque volume élémentaire étant modélisé par un réseau réluctant local, le découpage de la géométrie conduit à la génération automatique du système algébrique magnétique de la structure et dont la solution fournit la distribution locale du potentiel scalaire magnétique aux nœuds des volumes élémentaires. Cette approche de modélisation a été implémentée dans un code de calcul interne au GREAH. La modélisation de la génératrice à flux axial par réseaux réluctants a été validée par des simulations 2D et 3D par éléments finis. Le code de calcul développé intègrera les travaux en cours sur les modèles thermique et mécanique au GREAH afin d'aboutir à un code de calcul multi-physique par constantes localiséesThe aim of this PhD thesis is to propose a design approach of the axial flux permanent magnet synchronous generator for multi megawatts wind converter application. The axial flux permanent magnet synchronous machine being intrinsically three dimensional, a 3D multiphysics sizing model is needed in order to conduct an efficient optimal design of this type of machines. Unfortunately, 3D multiphysic models are generally issued from finite element method. So, they are very heavy to be handled in a reduced time from an engineer point of view and especially at the first stages of the design procedure. In order to address the faster axial flux machine design, this PhD thesis develops a lumped parameters approach modelling offering a good computation time to precision ratio and thus helping to reduce considerably the spent time in the first stages design procedure. The lumped parameters modelling approach is also well suited for the modelling of the three main physics to be considered in an electrical generator (magnetic model, thermal model and mechanical model). For the magnetic model, the lumped parameters approach consists, in this thesis, in the development of a generic magnetic reluctance network linked to the machine geometry. In fact, the latter is divided into parallelepipedic elementary volumes, each of them is modelled by a local reluctance network. The reluctance network of the hole machine geometry results then automatically in an algebraic magnetic system, the solution of which provides the distribution of the scalar magnetic potential at the elementary volume nodes. The described lumped parameters modelling was implemented in a computational code developed at the GREAH Lab. The effectiveness of the reluctance network axial flux machine modelling was validated by 2D and 3D finite element simulations. The lumped parameters computational code will regroup the ongoing developments of thermal and mechanical models at the GREAH Lab in order to reach the completion of a mutliphysics lumped parameters computational code
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Muhammad, Zakir Hossain. "High resolution ultrasonic monitoring of muscle dynamics and novel approach to modelling." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-102502.
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The presented work is concerned with the development and application of an ultrasonic detection scheme suitable for the monitoring of muscle dynamics with high temporal - down to 5 µs - and spatial resolution - down to 0.78 µm. A differential detection scheme has been developed to monitor the variations of the velocity of longitudinal polarized ultrasound waves travelling in contracting and relaxing muscle, compensating for variations of the path length by referencing to a frame. The observed time dependent variations of the time-of-flight of the ultrasonic waves caused by variations in the muscle and in addition by minor deformations of the enclosure are detected each separately and synchronously and are evaluated differentially. Beside of the detected increase of the speed of sound observed for contracted muscle with respect to the relaxed state of about 0.6%, the recovery time from maximum isometric contraction is quantified and relaxation processes are observed for the recovery phase following the isometric contraction. The developed ultrasonic calliper was employed to monitor both, the brain controlled and externally excited muscle dynamics with sampling intervals down to 10 ms synchronously with signals relating to the excitation. Monitored are the activation, hold, and relaxation phase for maximum voluntary isometric contraction of the gastrocnemius muscle. A so far not reported post tetanus overshoot and subsequent exponential recovery are observed. Both are attributed to the muscle as suggested by combined monitoring with EMG and are modelled with a lumped mechanical circuit containing an idealized bidirectional linear motor unit, ratchet, damper, and springs. Both, the rapid contraction and relaxation phases require a high order filter or alternatively a kernel filter, attributed to the nerve system as suggested by external electric stimulation. The respective response function is modelled by an electrical lumped circuit. Together with a reaction time and occasionally observed droops in the hold phase, both adjusted empirically, the monitored response is represented in close approximation by the combined electrical and mechanical lumped circuits. The respectively determined model parameters provide a refined evaluation scheme for the performance of monitored athletes. Valuable parameters relate to the latent period, the muscle response time, the activation and deactivation dynamics, a possible droop and other instabilities of the hold phase, and parameters characterizing the relaxation phase including the observed post tetanus overshoot and subsequent contraction. Monitored and modelled are also the different processes involved in active muscle dynamics including isotonic, isometric, and eccentric contraction or stretching. The developed technology provides time sequential observation of these processes and registration of their path in the extension and force parameter space. Under suitable conditions the closed-loop cycles of mind controlled human muscle movements proceed along characteristic lines coinciding with well identifiable elementary processes. The presentation of the monitored processes in the extension and force parameter space allows the determination of the mechanical energy expenditure for the observed different muscle actions. An elementary macroscopic mechanical model has been developed, suitable to express the basic features of the monitored muscle dynamics.
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Perez, Javier Rodriguez. "A hybrid strategy for improved state estimation in nonlinear lumped and distributed parameter models." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516501.
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Paudel, Murari. "An Examination of Distributed Hydrologic Modeling Methods as Compared with Traditional Lumped Parameter Approaches." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2219.
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Empirically based lumped hydrologic models have an extensive track record of use where as physically based, multi-dimensional distributed models are evolving for various engineering applications. Despite the availability of high resolution data, better computational resources and robust numerical methods, the usage of distributed models is still limited. The purpose of this research is to establish the credibility and usability of distributed hydrologic modeling tools of the United States Army Corps of Engineers (USACE) in order to promote the extended use of distributed models. Two of the USACE models were used as the modeling tools for the study, with Gridded Surface and Subsurface Hydrologic Analysis (GSSHA) representing a distributed and with Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) representing a lumped model. Watershed Modeling System (WMS) was used as the pre- and post-processing tool. The credibility of distributed models has been established by validating that the distributed models are efficient in solving complex hydrologic problems. The distributed and lumped models in HEC-HMS were compared. Similarly, the capabilities of GSSHA and lumped models in HEC-HMS in simulating land use change scenario were compared. The results of these studies were published in peer-reviewed journals. Similarly, the usability of the distributed models was studied taking GSSHA-WMS modeling as a test case. Some of the major issues in GSSHA-modeling using WMS interface were investigated and solutions were proposed to solve such issues. Personal experience with GSSHA and feedback from the students in a graduate class (CE531) and from participants in the USACE GSSHA training course were used to identify such roadblocks. The project being partly funded by the USACE Engineering Research and Development Center (ERDC) and partly by Aquaveo LLC, the research was motivated in improving GSSHA modeling using the WMS interface.
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Banus, Cobo Jaume. "Coeur & Cerveau. Lien entre les pathologies cardiovasculaires et la neurodégénérescence par une approche combinée biophysique et statistique." Thesis, Université Côte d'Azur, 2021. http://www.theses.fr/2021COAZ4030.
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Les études cliniques ont identifié plusieurs facteurs de risque cardiovasculaire associés à la démence et aux pathologies cardiaques, mais leur interaction pathologique reste mal comprise. Habituellement, l'étude de la relation cœur-cerveau est réalisée à travers d'analyses statistiques explorant l'association entre les indicateurs cardiaques et les biomarqueurs cognitifs. Ce type d'étude est généralement réalisé dans des bases de données épidémiologiques, pour lesquelles des mesures conjointes du cerveau et du cœur sont disponibles. Par conséquent, la généralisation de ces résultats aux études sur la démence est difficile, car les évaluations approfondies des fonctions cardiovasculaires dans les bases de données sur la démence actuellement disponibles font généralement défaut. Un autre facteur limitatif des études actuelles est l'interprétabilité limitée des relations physiopathologiques entre le cœur et le cerveau. L'amélioration de notre compréhension des implications de la fonction cardiovasculaire dans la démence nécessite le développement de modèles mécniaques de la physiologie cardiaque, ainsi que le développement de nouvelles approches permettant d'intégrer ces modèles avec des biomarqueurs cérébraux basés sur l'image. Pour relever ces défis, nous avons développé dans cette thèse de nouveaux outils informatiques basés sur l'intégration de modèles mécaniques dans un cadre d'apprentissage statistique. Premièrement, nous avons étudié l'association entre des indicateurs physiologiques non observables, tels que la contractilité cardiaque, et des caractéristiques d'imagerie dérivées du cerveau. À cette fin, l'espace des paramètres d'un modèle mécanique de la fonction cardiaque a été contraint pendant l'étape de personnalisation sur la base des relations entre les paramètres du modèle cardiaque et les informations cérébrales. Cela permet d’attenuer le caractère mal defini du problème inverse associé à la personnalisation du modèle, et d'obtenir des solutions spécifiques au patient qui sont comparables au sein de la population.Deuxièmement, nous avons développé un modèle d'imputation probabiliste qui permet d'imputer les informations cardiaques manquantes dans des bases de données limitées. L'imputation repose sur les dynamiques cœur-cerveau apprises à partir de l'analyse d'une grande population de sujets, et utilise cette connaissance pour obtenir des solutions plausibles dans des bases de données partielles. La nature générative de l'approche permet de simuler l'évolution des paramètres du modèle cardiaque lorsque les caractéristiques du cerveau changent. Troisièmement, nous avons analysé le rôle des paramètres du modèle cardiaque comme biomarqueurs précoces de la démence, ce qui pourrait aider à identifier les individus à risque. Dans ce but, nous avons imputé les informations cardiaques manquantes dans une cohorte longitudinale de la maladie d'Alzheimer. Ensuite, grâce à la modélisation de la progression de la maladie, nous avons estimé le stade de la maladie pour chaque individu sur la base de l'évolution des biomarqueurs. Ceci a permis d'obtenir un modèle de l'évolution de la maladie, d'analyser le rôle de la fonction cardiaque, et d'identifier les paramètres du modèle cardiaque comme biomarqueurs potentiels de la démence à un stade précoce. Les résultats démontrent l'importance des outils développés en obtenant des associations cliniquement plausibles entre les paramètres du modèle cardiaque et les caractéristiques de l'imagerie cérébrale. Ces résultats mettent également en évidence des informations sur la relation physiologique entre la fonction cardiaque et les biomarqueurs de la démence. Les résultats obtenus ouvrent de nouvelles voies de recherche, telles que l'utilisation de modèles mécaniques plus complexes permettant de mieux caractériser la relation cœur-cerveau, ou l'utilisation de modèles cardiaques biophysiques pour dériver des biomarqueurs in-silico afin d'identifier les individus à risque de démenceClinical studies have identified several cardiovascular risk factors associated to dementia and cardiac pathologies, but their pathological interaction remains poorly understood. Classically, the investigation of the heart-brain relationship is mostly carried out through statistical analysis exploring the association between cardiac indicators and cognitive biomarkers. This kind of investigations are usually performed in large-scale epidemiological datasets, for which joint measurements of both brain and heart are available. For this reason, most of these analyses are performed on cohorts representing the general population. Therefore, the generalisation of these findings to dementia studies is generally difficult, since extensive assessments of cardiac and cardiovascular function in currently available dementia dataset is usually lacking. Another limiting factor of current studies is the limited interpretability of the complex pathophysiological relations between heart and brain allowed by standard correlation analyses. Improving our understanding of the implications of cardiovascular function in dementia ultimately requires the development of more refined mechanistic models of cardiac physiology, as well as the development of novel approaches allowing to integrate these models with image-based brain biomarkers. To address these challenges, in this thesis we developed new computational tools based on the integration of mechanistic models within a statistical learning framework. First, we studied the association between non-observable physiological indicators, such as cardiac contractility, and brain-derived imaging features. To this end, the parameter-space of a mechanistic model of the cardiac function was constrained during the personalisation stage based on the relationships between the parameters of the cardiac model and brain information. This allows to tackle the ill-posedness of the inverse problem associated to model personalisation, and obtain patient-specific solutions that are comparable population-wise.Second, we developed a probabilistic imputation model that allows to impute missing cardiac information in datasets with limited data. The imputation leverages on the cardiac-brain dynamics learned in a large-scale population analysis, and uses this knowledge to obtain plausible solutions in datasets with partial data. The generative nature of the approach allows to simulate the evolution of cardiac model parameters as brain features change. The framework is based on a conditional variational autoencoder (CVAE) combined with Gaussian process (GP) regression. Third, we analysed the potential role of cardiac model parameters as early biomarkers for dementia, which could help to identify individuals at risk. To this end, we imputed missing cardiac information in an Alzheimer's disease (AD) longitudinal cohort. Next, via disease progression modelling we estimated the disease stage for each individual based on the evolution of biomarkers. This allowed to obtain a model of the disease evolution, to analyse the role of cardiac function in AD, and to identify cardiac model parameters as potential early-stage biomarkers of dementia. These results demonstrate the importance of the developed tools by providing clinically plausible associations between cardiac model parameters and brain imaging features in an epidemiological dataset, as well as highlighting insights about the physiological relationship between cardiac function and dementia biomarkers. The obtained results open new research directions, such as the use of more complex mechanistic models that allow to better characterise the heart-brain relationship, or the use of biophysical cardiac models to derive in-silico biomarkers for identifying individuals at risk of dementia in clinical routine, and/or for their inclusion in neuroprotective trials
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Yevseienko, Oleg, Anatoliy Gapon, and Dmytro Salnikov. "Searching for Optimal Control Parameters of Thermal Object Using Pulse-Width Modulation (PWM) Control with Predictive Filter." Thesis, Lviv Polytechnic Publishing House, 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/41116.
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The thesis is devote to the temperature control of objects with lumped or distributed parameters. The problems of choosing the right value of regulator’s heater power and prediction period are discussed. The major attention is paid to the process of searching the minimum value of control quantities. It is shown that the approximated second-order plane has an exact accordance with the original data. It is concluded that algorithm of PWM-control with prediction filter provides good quality control.
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Oksar, Irfan. "Design And Realization Of Mixed Element Broadband Bandpass Filters." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/4/1092964/index.pdf.
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In this thesis, a highly selective broadband hybrid bandpass filter operating between 0.4-2.0 GHz with a stopband up to 7 GHz is designed and analyzed. The realization is carried out by hybrid method, which combines both lumped and distributed element filters. In this approach, two separate filters, which are lumped highpass with 0.4 GHz corner frequency and distributed stripline lowpass with 2 GHz corner frequency, are combined to get the bandpass filter that has a passband in between 0.4 to 2.0 GHz. The usage of the lumped elements for the highpass filter resulted in a great size reduction compared to distributed element approach. The design software FILPRO&tradeis used to synthesize the trial filters. More than forty filters are synthesized, and among them, the ones that have better properties are chosen for further processes. Optimization, modeling and electromagnetic simulations of the selected lumped and distributed filters are carried out on the software GENESYS&trade
. Distributed filters are also simulated using the software SONNET&trade
. After the simulations, all of the simulated filters are realized and measured, and the level of consistency with the simulations is observed. According to the results of the measurements, the filter combination that has the best combination of low insertion loss, small dimensions, high stopband attenuation and low spur levels is selected for the final bandpass filter structure and a few variants are examined to get the final structure.
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Tratkanov, Dimitri. "Méthodes géométriques et énergétiques pour la modélisation et la simulation des systèmes multi-physiques en génie électrique." Thesis, Compiègne, 2020. http://www.theses.fr/2020COMP2562.
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L’objectif de ce travail de recherche est de proposer un nouveau concept pour la génération automatique de réseaux équivalents à partir de calculs de type éléments finis (TEF). La réduction d’ordre du modèle s’appuie sur des techniques informatiques de clustering qui segmentent la géométrie réelle en un nombre restreint d’ensembles à champs homogène. La distribution des champs dans la géométrie est calculée à partir de résultats d’une méthode TEF (plus précisément, il s’agit d’une Cell-Method) et à l’aide d’éléments de Whitney. Ces ensembles homogènes peuvent alors être regroupés (fusionner) pour générer les composants du réseau équivalent. Les techniques présentées dans ces thèses sont illustrées sur un exemple magnétostatique permettant, à partir du calcul du potentiel vecteur magnétique sur un maillage TEF, de générer un réseau de reluctance précis mais d’ordre très réduit par rapport au modèle initialThis PhD thesis deals with modeling and computational methods for the design of multi-physical devices in the context of Model-Based System Engineering (MBSE). The proposed methods are based on geometric and topological tools (differential and algebraic topology) as well as duality theory (energetic and differential forms) and advanced discretization and meshing techniques (Delaunay- Voroinoi mesh and computer graphics tools). Analogies so useful in multi-physics modeling are widely used in this work through Tonti's perspective and diagrams. Several standard approaches to engineering modelling are extended and complemented by machine learning and clustering algorithms to provide innovative methods for modeling, simulation and model order reduction. The main contribution of this work concerns a new concept of automated generation of lumped parameter (LP) models from field computations. The results of the field calculations are obtained with a cochain method inspired by the Discrete External Calculus and the Tonti's Cell-Method. This thesis proposes an original approach which generates a LP model and applies at the same time a model order reduction. The two objectives, the automatic generation of the LP model and the model reduction, are based on a topological analysis of the physical problem and Artificial Intelligence clustering algorithms. The final objective of this work is to propose a multi-scale model that can simplify the modeling and simulation of multi-physical devices. This multi-scale model should be suitable for both: solution analysis (computation of fields with the cochain model) and design, optimization, control synthesis (computation of physical quantities in a network of components with the LP model). Field computations are illustrated on a weakly coupled multi-physical case: Electrokinetic, then thermal, and finally mechanical field are computed. Model order reduction and automatic LP generation are illustrated on a magnetostatic case (based on an electromagnetic device): the magnetic H and B fields are calculated using the cochain method, then a reduced reluctance network is automatically generated from the field results. In this example, the number of degrees of freedom is almost reduced by a factor of one hundred
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Yayla, Ihsan. "Filter Design Software By Synthesis Method." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610279/index.pdf.
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In this study, Window-based computer program, named Synthesis Software, is developed for
designing filters with equal-ripple or maximally flat passbands and general stopbands by using
cascade synthesis technique in transformed frequency domain. Synthesis technique is applicable
to lumped element and commensurate line distributed element filters with Lowpass,
Highpass or Bandpass characteristics. Singly or Doubly terminated filters can be synthesized. friendly environment for typing in the parameters of the filter to be designed. This part uses
Synthesis and Plot parts as modules.
This software is based on the previous softwares developed in EEE Department of Middle
East Technical University. All the previous softwares were gathered in the well-known software
Filpro, which is in DOS environment, in Pascal. Thus, the new software is actually a
conversion of Synthesis part of Filpro from DOS environment into Windows environment in
the language C#, with some improvements in root finding algorithms for numerical conditioning.
Synthesis Software is has three parts. The first and main part is the implementation
of synthesis technique by using object oriented programming technique. In this way, synthesis
technique implementation is isolated from other parts of Synthesis Software and it can be
used by other filter design programs as a module. The second part of the program is responseplotting
section. In this part Insertion Loss, Return Loss, Time Delay, Phase and Smith Chart
responses are calculated and displayed. The last part is User Interface, which provides user
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Santos, Franciane Mendonça dos. "Modelagem concentrada e semi-distribuída para simulação de vazão, produção de sedimentos e de contaminantes em bacias hidrográficas do interior de São Paulo." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-26112018-145857/.
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A escassez de dados hidrológicos no Brasil é um problema recorrente em muitas regiões, principalmente em se tratando de dados hidrométricos, produção de sedimentos e qualidade da água. A pesquisa por modelos de bacias hidrográficas tem aumentado nas últimas décadas, porém, a estimativa de dados hidrossedimentológicos a partir de modelos mais sofisticados demanda de grande número de variáveis, que devem ser ajustadas para cada sistema natural, o que dificulta a sua aplicação. O objetivo principal desta tese foi avaliar diferentes ferramentas de modelagem utilizadas para a estimativa da vazão, produção de sedimentos e qualidade da água e, em particular, comparar os resultados obtidos de um modelo hidrológico físico semi-distribuído, o Soil Water Assessment Tool (SWAT) com os resultados obtidos a partir de modelos hidrológicos concentrados, com base na metodologia do número da curva de escoamento do Soil Conservation Service (SCS-CN) e no modelo Generalized Watershed Loading Function (GWLF). Buscou-se avaliar e apresentar em quais condições o uso de cada modelo deve ser recomendado, ou seja, quando o esforço necessário para executar o modelo semi-distribuído leva a melhores resultados efetivos. Em relação à simulação da vazão, os resultados dos dois modelos foram altamente influenciados pelos dados de precipitação, indicando que existem, possivelmente, falhas ou erros de medição que poderiam ter influenciado negativamente os resultados. Portanto, foi proposto aplicar o modelo semi-distribuído com dados de precipitação interpolados (DPI) de alta resolução para verificar a eficiência de seus resultados em comparação com os resultados obtidos com a utilização dos dados de precipitação observados (DPO). Para simulação da produção de sedimentos, e das concentrações de nitrogênio e fósforo, o SWAT realiza uma simulação hidrológica mais detalhada, portanto, fornece resultados ligeiramente melhores para parâmetros de qualidade da água. O uso do modelo semi-distribuído também foi ampliado para simular uma bacia hidrográfica sob a influência do reservatório, a fim de verificar a potencialidade do modelo para esse propósito. Os modelos também foram aplicados para identificar quais os impactos potenciais das mudanças no uso do solo previstas e em andamento. Os cenários estudados foram: I – cenário atual, II – cenário tendencial, com o aumento da mancha urbana e substituição do solo exposto e de parte da mata nativa por uso agrícola; III – cenário desejável, complementa o crescimento urbano tendencial com aumento de áreas de reflorestamento. As metodologias foram aplicadas em duas bacias hidrográficas localizadas no Sudeste do Brasil. A primeira é a bacia do rio Jacaré-Guaçu, incluída na Unidade de Gerenciamento de Recursos Hídricos 13 (UGRHI-13), a montante da confluência do rio das Cruzes, com uma área de 1934 km2. O segundo caso de estudo, é a bacia do rio Atibaia, inserida na UGRHI-5, tem uma área de 2817,88 km2 e abrange municípios dos estados de São Paulo e Minas Gerais. Como principal conclusão, o desempenho do modelo semi-distribuído para estimar a produção de sedimentos, e as concentrações de nitrogênio e fósforo foi ligeiramente melhor do que as simulações do modelo concentrado SCS-CN e GWLF, mas essa vantagem pode não compensar o esforço adicional de calibrá-lo e validá-lo.The lack of hydrological data in Brazil is a recurrent problem in many regions, especially in hydrometric data, sediment yield and water quality. The research by simplified models has increased in the last decades, however, the estimation of hydrossedimentological data from these more sophisticated models demands many variables, which must be adjusted for each natural system, which makes it difficult to apply. At times it is necessary to respond quickly without much precision in the results, in these situations, simpler models with few parameters can be the solution. The objective of this research is to evaluate different modelling tools used estimate streamflow, sediments yield and nutrients loads values, and namely to compare the results obtained from a physically-based distributed hydrological model (SWAT) with the results from a lumped hydrological, the Soil Conservation Service (SCS-CN) and the Generalized Watershed Loading Function (GWLF) model. Both models use the curve number (CN) concept, determined from land use, soil hydrologic group and antecedent soil moisture conditions and were run with a daily time step. We are particularly interested in understanding under which conditions the use of each model is to be recommended, namely when does the addition effort required to run the distributed model leads to effective better results. The input variables and parameters of the lumped model are assumed constant throughout the watershed, while the SWAT model performs the hydrological analysis at a small unit level, designated as hydrological response units (HRUs), and integrates the results at a sub-basin level. In relation to the flow simulation, the results of the two models were highly influenced by the rainfall data, indicating that, possibly, faults or measurement errors could have negatively influenced the results. Therefore, it was proposed to apply the distributed model with high-resolution grids of daily precipitation to verify the efficiency of its results when compared to rainfall data. For simulation of sediment, nitrogen and phosphorus, SWAT performs a more detailed simulation and thus provides slightly better results. The use of the SWAT was also extended to simulate the influence of reservoir, in order to verify the potentiality of the model, in relation to the simulation. The models also were used to identify which are potential impacts of the ongoing land use changes. The scenarios were: I - Current scenario, II - trend scenario, with the increase of urban land and replacement of the exposed soil and part of the native forest by agricultural use; III - desirable scenario complements the trend urban growth with the replacement of exposed soil and part of the agricultural use by reforestation. The methodologies were applied on two watersheds located in the Southeast of Brazil. The first one is the Jacaré-Guaçu river basin, included in the Water Resources Management Unit 13 (UGRHI-13), upstream of Cruzes river confluence, with an area of 1934 km2. The second watershed is the Atibaia River Basin, a part of Water Resources Management Unit 5 (UGRHI-5). It has an area of 2817.88 km2 and covers municipalities of the states of São Paulo and Minas Gerais.
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Goodpaster, Benjamin A. "Analytical Modeling and Impedance Characterization of Nonlinear, Steady-State Structural Dynamics in Thermomechanical Loading Environments." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524063139635613.
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Karisan, Yasir. "Full-wave Electromagnetic Modeling of Electronic Device Parasitics for Terahertz Applications." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1419019102.
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Whalley, R., Kambiz M. Ebrahimi, and A. A. Abdul-Ameer. "Hybrid modelling of machine tool axis drives." 2005. http://hdl.handle.net/10454/3951.
Full textAbstract:
NoThe x-axis dynamics of a milling machine where the workpiece and saddle are mounted on supporting slides is considered. A permanent magnet motor, lead screw, ball nut and bearings are employed as the machine, traverse actuator mechanism. Hybrid, distributed¿lumped parameter methods are used to model the machine tool x-axis drive system. Inclusion of the spatial configuration of the drive generates the incident, travelling and reflected vibration signature of the system. Lead screw interactive torsion and tension loading, which is excited by cutting and input disturbance conditions, is incorporated in the modelling process. Measured and results from simulation exercises are presented in comparative studies enabling the dynamic characteristics of the machine to be identified under, no load and with the application of cyclic, cutting force disturbances. The effect of the lead screw length, cutting speed and hence the load disturbance frequency are examined and the resulting performance accuracy is commented upon.
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John, Yakubu M., M. A. Mustafa, Rajnikant Patel, and Iqbal M. Mujtaba. "Parameter estimation of a six-lump kinetic model of an industrial fluid catalytic cracking unit." 2018. http://hdl.handle.net/10454/16539.
Full textAbstract:
YesIn this work a simulation of detailed steady state model of an industrial fluid catalytic cracking (FCC) unit with a newly proposed six-lumped kinetic model which cracks gas oil into diesel, gasoline, liquefied petroleum gas (LPG), dry gas and coke. Frequency factors, activation energies and heats of reaction for the catalytic cracking kinetics and a number of model parameters were estimated using a model based parameter estimation technique along with data from an industrial FCC unit in Sudan. The estimated parameters were used to predict the major riser fractions; diesel as 0.1842 kg-lump/kg-feed with a 0.81% error while gasoline as 0.4863 kg-lump/kg-feed with a 2.71% error compared with the plant data. Thus, with good confidence, the developed kinetic model is able to simulate any type of FCC riser with six-lump model as catalyst-to-oil (C/O) ratios were varied and the results predicted the typical riser profiles.
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Kuo, Tsung-Nan, and 郭宗男. "Compact Distributed-Lumped Microstrip Bandpass Filters." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/98711753512688733592.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
93
In this study, novel compact distributed-lumped microstrip bandpass filters, based on folded quarter-wavelength(λ/4) resonators, are proposed. Two transmission zeros at upper and lower stopbands are created by introducing a cross-coupling capacitance directly between the input and output ports of a 2nd-order filter. This pair of transmission zeros would not degrade the passband insertion loss and may improve the selectively. In order to achieve good spurious response and small circuit area, suitable open stubs and stepped impedance resonators are adopted in the filter design. The improved results are verified through experiments. Moreover, a novel 4th-order filter is also implemented. By suitably introducing two capacitive cross-coupling paths in the 4th-order filter, improved selectivity and good stopband rejection can be achieved.
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chang, Jann-yuan, and 張振源. "Applications of lumped and distributed runoff models in Shihmen reservoir watershed." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/64652349314006819221.
Full textAbstract:
碩士國立臺灣海洋大學
河海工程學系
95
Abstract Watershed rainfall-runoff simulation can be classified into lumped routing and distributed routing. The unit hydrograph, which is the hydrologic response function for a unit rainfall input at the watershed outlet, is the well-known lumped model. By using continuity equation and momentum equation, a distributed routing model associated with a conceptual model can simulate the propagation of flood wave in the watershed. The purpose of this study is to investigate the differences in rainfall-runoff simulating using the lumped model and the distributed model. In this study, the HEC-GeoHMS was applied to obtain the stream network, subwatershed boundary, and geomorphic factors. Consequently, the kinematic-wave V-shaped model in the HEC-HMS was applied to perform the runoff routing from a lumped system to distributed systems. The methodology was applied to the upstream watershed of Hsia-Yun, which is located in the Shihmen Reservoir watershed. In performing the lumped and distributed runoff routing, the watershed was divided into 1, 5, 9, and 14 subwatersheds. Hydrological records from four typhoon events were selected for model simulations. The results show that the channel roughness coefficient calibrated by using a distributed model is larger than that calibrated by using a lumped model. Moreover, the roughness coefficient calibrated in the upstream subwatersheds is larger than that obtained from the downstream subwatersheds. The simulation results generated by using the kinematic-wave V-shaped model were also compared with the results generated from a kinematic-wave based GIUH model. Key word: HEC-GeoHMS、HEC-HMS、Distributed runoff models、Lumped runoff models、KW-GIUH
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Yang, Hsi-Ming, and 楊錫明. "Parallel-Coupled Bandpass Filters Based on Lumped-Distributed Coupled-Line Sections." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/47569831261817809514.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
93
In this study, parallel-coupled bandpass filters based on lumped-distributed coupled-line sections have been proposed to possess the merits of compact size, good selectivity, and good stopband rejection. Novel parallel-coupled bandpass filters are proposed, by using additional lumped capacitors or inductors to reduce the length of coupled-line sections. In addition, by introducing the capacitive or inductive cross-coupling effect, transmission zeros can be achieved to improve the filter selectivity. The locations of transmission zeros may be simply adjusted by varying the cross-coupling capacitance or inductance. Simple equivalent-circuit models and design formulas are also established, from which the proposed parallel-coupled bandpass filters based on lumped-distributed coupled-line sections may be design and investigated. Furthermore, the approach to suppress the spurious response is also discussed so as to enhance the stopband characteristics.
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Kuan, Ming-Chih, and 官明志. "Analysis and synthesis of hybrid lumped-distributed circuits in z-domain." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/17865258213995766511.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
88
The ABCD transmission matrices of z-transform representation are developed for transmission line, capacitor and inductor in recent researches. Such representations facilitate the investigation of circuit having cascade connection of two or more two-port networks in both frequency and time domains. In particular, the z-transform representations of circuit elements make it possible to utilize many application tools developed in digital signal processing (DSP) study. Three z-transform representations for inductor and capacitor, such as backward-difference, bilinear, and central-difference z-transforms, are investigated in this thesis. Several examples, including circuit analysis and inverse consideration, are presented to illustrate the validity of z-transform representations in circuit design. Outlines of the thesis are as followings. Chapter 1 provides an introduction to the historical background of analysis method of lumped-distributed hybrid circuit, including time-, frequency-, and z-domain methods. In this thesis, we focus on the z-domain method. Chapter 2 presents the details of three different z-transforms: backward-difference, bilinear, and central-difference z-transforms. Chapter 3 shows some examples about circuit analysis and inverse consideration in circuit design. It also points out the differences between each z-transform method mentioned previously. Conclusion remarks are mad in chapter4.
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Muhammad, Zakir Hossain. "High resolution ultrasonic monitoring of muscle dynamics and novel approach to modelling." Doctoral thesis, 2005. https://ul.qucosa.de/id/qucosa%3A11817.
Full textAbstract:
The presented work is concerned with the development and application of an ultrasonic detection scheme suitable for the monitoring of muscle dynamics with high temporal - down to 5 µs - and spatial resolution - down to 0.78 µm. A differential detection scheme has been developed to monitor the variations of the velocity of longitudinal polarized ultrasound waves travelling in contracting and relaxing muscle, compensating for variations of the path length by referencing to a frame. The observed time dependent variations of the time-of-flight of the ultrasonic waves caused by variations in the muscle and in addition by minor deformations of the enclosure are detected each separately and synchronously and are evaluated differentially. Beside of the detected increase of the speed of sound observed for contracted muscle with respect to the relaxed state of about 0.6%, the recovery time from maximum isometric contraction is quantified and relaxation processes are observed for the recovery phase following the isometric contraction. The developed ultrasonic calliper was employed to monitor both, the brain controlled and externally excited muscle dynamics with sampling intervals down to 10 ms synchronously with signals relating to the excitation. Monitored are the activation, hold, and relaxation phase for maximum voluntary isometric contraction of the gastrocnemius muscle. A so far not reported post tetanus overshoot and subsequent exponential recovery are observed. Both are attributed to the muscle as suggested by combined monitoring with EMG and are modelled with a lumped mechanical circuit containing an idealized bidirectional linear motor unit, ratchet, damper, and springs. Both, the rapid contraction and relaxation phases require a high order filter or alternatively a kernel filter, attributed to the nerve system as suggested by external electric stimulation. The respective response function is modelled by an electrical lumped circuit. Together with a reaction time and occasionally observed droops in the hold phase, both adjusted empirically, the monitored response is represented in close approximation by the combined electrical and mechanical lumped circuits. The respectively determined model parameters provide a refined evaluation scheme for the performance of monitored athletes. Valuable parameters relate to the latent period, the muscle response time, the activation and deactivation dynamics, a possible droop and other instabilities of the hold phase, and parameters characterizing the relaxation phase including the observed post tetanus overshoot and subsequent contraction. Monitored and modelled are also the different processes involved in active muscle dynamics including isotonic, isometric, and eccentric contraction or stretching. The developed technology provides time sequential observation of these processes and registration of their path in the extension and force parameter space. Under suitable conditions the closed-loop cycles of mind controlled human muscle movements proceed along characteristic lines coinciding with well identifiable elementary processes. The presentation of the monitored processes in the extension and force parameter space allows the determination of the mechanical energy expenditure for the observed different muscle actions. An elementary macroscopic mechanical model has been developed, suitable to express the basic features of the monitored muscle dynamics.:Table of Contents
Chapter 1
1. Introduction 1
1.1 Monitoring of muscle biomechanics 1
1.2 Detection methods in biomechanics 2
1.3 Ultrasound in biomechanical application 5
1.4 Skeletal muscle 6
1.5 Activation of skeletal muscle 8
1.6 Catatonus effect 10
Chapter 2
2. Concepts and methods in ultrasonic motion monitoring 12
2.1 Ultrasound 12
2.2 Specific concepts of the developed ultrasonic detection scheme 16
2.2.1 Time-of-flight 17
2.2.2 Cross correlation 18
2.2.3 Concepts of cross correlation 19
2.2.4 Chirp technique 19
Chapter 3
3. Ultrasonic monitoring of the muscle extension 21
3.1 Data analysis 21
3.2 Application of the developed monitoring scheme 23
3.2.1 Fast signal and data acquisition mode 23
3.2.2 Monitoring with off-line evaluation 24
3.2.3 Method 26
3.2.4 Data evaluation 27
3.3 Quasi-continuous monitoring scheme 28
3.3.1 Slow with on-line data processing and display 29
3.3.2 Fast with data storage only 30
3.4 Monitoring with on-line evaluation 34
3.4.1 Application involving monitoring of athletic performance 36
3.4.2 Data evaluation 37
3.4.3 Summary 42
3.5 Comparative study of pre and post physical loading session 43
3.5.1 Method 43
3.5.2 Results 44
3.5.3 Summary 45
Chapter 4
4. High resolution monitoring of the velocity of ultrasound in contracting
and relaxing muscle 47
4.1 Methods 49
4.2 Results and evaluation 51
4.2.1 Poission’s ratio for isometrically contracted muscle 52
4.3 Summary 53
Chapter 5
5. Monitoring of muscle dynamics, muscle force, and EMG 56
5.1 Synchronous monitoring of muscle dynamics with muscle force 56
5.1.1 Force-length dynamics under all-out isometric contraction 56
5.1.1.1 Method 56
5.1.1.2 Result and evaluation 58
5.1.2 Force-length dynamics of equal holding monitoring 62
5.1.2.1 Method 62
5.1.2.2 Results and evaluation 63
5.1.3 Summary 67
5.2 Synchronous monitoring of muscle movement with EMG 69
5.2.1 Method 69
5.2.2 Results and evaluation 70
5.3 Synchronous monitoring of muscle movement, EMG and muscle force 73
5.3.1 Method 73
5.3.2 Results and evaluation 74
5.3.3 Summary 77
Chapter 6
6. Monitoring of skeletal muscle dynamics under isometric contraction and
modelling of the non-linear response including post tetanus effects 80
6.1 Method 82
6.2 Data analysis 82
6.3 Results and evaluation 82
6.3.1 Mechanical model 83
6.3.2 Equations relating to modelling 85
6.3.3 Comparison of experimental results and modelling 91
6.3.4 Electrical lumped circuit 93
6.4 Summary 100
Chapter 7
7. Lumped Circuit Model and Energy Transfer for quasi-static approximation 101
7.1 Basic muscle model and biomechanical processes 102
7.1.1 Muscle model 102
7.1.2 Force in the muscular motoric processes 104
7.2 Method 104
7.3 Results of experimental observations of muscle action 106
7.3.1 Muscle force and closed-loop contraction dynamics 106
7.3.2 Muscle work considerations 109
7.4 Summary 110
Chapter 8
8.1 Ultrasonic calliper 112
8.2 Interpretation of sound velocity variation in muscle 114
8.3 Monitored muscle dynamics 118
8.4 Isometric muscle action and tetanus effect 121
8.5 Quasi-static muscle action 125
8.6 Summarizing statement with a moderate outlook 126
References 128
Acknowledgements 140
Selbständigkeitserklärung 141
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Lu, Zheng-Liang, and 盧政良. "Analysis and Design of Lumped- and Distributed- Element Branch-Line Coupler with Arbitrary Power Division." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/42054620414191206096.
Full textAbstract:
碩士國立交通大學
電信工程系所
97
This thesis designs a 3-section wideband branch-line coupler with an arbitrary power division. Through the even/odd mode analysis, the arbitrary power division can be achieved by controlling the characteristic impedances of the branch lines. Meanwhile, for a specified power division, the fractional bandwidth can be predicted theoretically. The 3-section branch-line couplers are implemented by lumped elements and lumped distributed elements to reduce the circuit size. Theoretical analysis is validated by measurement results of experimental circuits.
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Shin, Sanghoon. "Theory and design of mixed lumped-distributed cross-coupled filters with applications to linear phase shifter and tunable filters." Thesis, 2002. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2002-053.
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Goodrow, Sandra M. "Hydrological modeling for the regional stormwater management plan an application and intercomparison of event based runoff generation in an urban catchment using empirical, lumped vs. physical, distributed parameter modeling /." 2009. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000051353.
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