1,067 research outputs found
A Study of Jewish Philanthropic Company Colonization in Canada`s Northwest Territories During the Late Nineteenth Century
No full textSince the author of this study is of Mennonite ethnic origin it
is perhaps in order to explain how he came to write this study of an
aspect of Jewish History. As an undergraduate his interests lay in
modern European History and Russian Intellectual History during the late
nineteenth century. In 1975, however, his attention was drawn to a
national essay competition sponsored by the Jewish Historical Society of
Western Canada in honour of the Bronfman Family. The author was able to
complete a paper, 'Jewish Agricultural Settlement in Western Canada,
1870-1930' while doing contract research related to the development of a
travelling display for the Western Development Museum in Saskatoon
during the summer of 1976. Dr. T.D. Regehr, who supervised the research
permitted the paper to be submitted to the contest and it was awarded
second prize of $200.
Al though the paper was based on available secondary sources
only, the author had been able to ascertain that there were primary
sources available for more detailed study of aspects of Jewish
Agricultural Settlement in the West. The author's attention was drawn
to Hirsch Colony in particular because of the sharply divergent
portrayals of its history and role in the development of Jewish
agriculture in Western Canada. Jewish literature suggested that it was
at least a moderate success and that it contributed significantly to the
later improvement of Jewish agriculture's progress in the West.
Government sources often quoted in the secondary sources, however, were
generally very negative about Jewish agriculture in general and about
Hirsch Colony in particular. This intrigued the author and resulted in
this study of the Colony's role in determining the direction taken by
Jewish Agricultural Colonization in Western Canada and its influence on
Dominion Lands Policy regarding assisted settlement in general and
Jewish agriculture in particular.
This study grew out of the natural curiosity sparked by the
essay contest, the contract research, and the author's own interest in
the ethnic variety and agricultural foundations of Western Canada
Studies in Singular Optics and Coherence Theory
No full textIn this dissertation, the field of singular optics is examined in terms of common laboratory experiments. Different types of field singularities are related to one another. Problems in coherence theory related to two correlated sources are also investigated.Electrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
Studies in Physical Optics: Coherence Theory and Surface Plasmons
No full textTelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Brushless Doubly-Fed Induction Machines for Wind Turbine Drive-Train Applications
No full textThe research leading to these results has received funding from the European Union’s Seventh framework Programme (FP7/2007_2013) for theWindrive project under Grant Agreement 315485.Electrical Power Processin
Discontinious Galerkin formulations for thin bending problems
No full textA structural thin bending problem is essentially associated with a fourth-order partial differential equation. Within the finite element framework, the numerical solution of thin bending problems demands the use of C^1 continuous shape functions. Elements using these functions are challenging and difficult to construct. A particular discontinuous Galerkin method has been used to deal with thin bending problems. It exploits standard Lagrange finite element basis functions with displacement degrees-of-freedom only. The method relies on a lifting operation to transform jumps in the normal derivative across element boundaries to a field defined on element interiors. By introducing special integrals over element boundaries, continuity requirements associated with thin bending problems are met weakly while consistency of the Galerkin problem is preserved and the stability of the formulation is controlled. The approach is formulated for a range of bending problems. Firstly, a finite element formulation for linear Kirchhoff plates is proposed. The formulation is analysed in terms of stability and convergence. A priori error estimates are supported by a range of numerical examples, including static plate bending, plate buckling and vibration. The method has also been developed for geometrically linear and nonlinear thin shell models. For geometrically nonlinear problems, an exact linearisation of the proposed formulation is presented. Using the approach, a non-smooth shell geometry can be dealt with. The performance of the approach is demonstrated via a range of numerical benchmark tests for both geometrically linear and nonlinear thin shells. Based on the obtained results, it can be concluded that the proposed formulation is robust, accurate and relatively simple. As a thin shell theory has been addressed directly, shear locking is completely avoided. Although membrane locking exists, it can be alleviated when high-order basis functions are used. Cubic elements perform particularly well in various challenging benchmark tests. The method is general in sense that it does not rely on a particular element type or shape.Civil Engineering and Geoscience
Suspended pipeflow with openfoam
No full textIn dredging applications, deep sea mining and land reclamation projects typically large amounts of sediments are transported through pipes in the form of hyper concentrated (40% sediment or more) sediment-water mixtures or slurry. These slurries can flow at three different regimes. 1: fully suspended (homogeneous and stratified) 2: partially suspended with a sliding bed 3: partially suspended with a fixed bed. At the moment it is hard to predict the transport regime, the volume flux of particles and the pressure drop (friction factor) of these slurries within these regimes. The goal is to establish a model 3D continuum model that is able to predict the aforementioned aspects of slurry flow in a wide range of slurry flow conditions. In this paper it is investigated how well an existing CFD-model is able to model velocity and concentration profiles of suspended sediment in a pipeline. The CFD-model that is used is TwoPhaseEulerFoam which is part of OpenFOAM. This Euler-Euler solver treats both the phases as a continuum with its own momentum and continuity equations. The phases are coupled with coupling terms such as the drag force.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Offshore and Dredging Engineerin
The Development of Range Extender Generator By Evaluating The Eddy Current Losses and End Effect Using FE Method
No full textPeec-Power B.V. is developing high power range extender for hybrid electric vehicles. The first generator designs for range extender have been built and tested in the laboratory. The prototype generators use a permanent magnets with a radial flux type. These prototypes use two kinds of fractional-slot concentrated winding. The slot pole combinations that were chosen are a multiple of 9 coils around 9 teeth with 8 magnet poles and a multiple of 3 coils around 3 teeth with 2 magnet poles. There are two types of permanent magnet constructions in the rotor, which are the Surface Mounted Permanent Magnet (SMPM) and Inset Permanent Magnet (IPM). This thesis deals with further development of the range extender generator. Two topics will be further investigated by using 2D and 3D FEM model. The first topic is the investigation of eddy current losses in the permanent magnets and rotor back iron. The second topic is the investigation of the influence of the machine ends and end windings on the flux distribution and inductivity. The rotor eddy current losses in the prototypes machine are calculated using analytic model, 2D FEM and 3D FEM model. The 3D FEM model is used to investigate the finite length effect in 2D FEM magnet loss calculations. This investigation needs to be done since the prototype generators have a short axial length. The lamination effect on the magnet loss also will be investigated in 3D FEM model. From this investigation, a correction factor to the 2D FEM magnet loss calculation is introduced. 3D FEM models are built to investigate the influence of the machine ends and end windings. With these models, the flux leakages, end inductances and the eddy current losses in the stator end are calculated.Electrical power processingElectrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc
A ioyful nevv ballad, declaring the happie obtaining of the great galleazo, wherein Don Pietro de Valdez was the chiefe through the mightie power and prouidence of God, being a speciall token of his gracious and fatherly goodnes towards vs, to the great encouragement of all those that willingly fight in the defence of his gospel and our good Queene of England. To the tune of mounseurs Almaigne.
No full text1 sheet ([1] p.) : ill.Signed at end: T.D. = the author, Thomas Deloney.Verse - "O noble England,".Reproduction of the original in the British Library
Control Algorithm for a BDFIG based Wind Turbine Drivetrain including Rotor Position Estimation.
No full textAs the need for electrical power from sustainable energy sources is continually increasing, electrical power generation from wind turbines continues to grow. A common type of electrical generators used in wind turbines is the Doubly Fed Induction Generator. However, this type of generator suffers from reliability issues associated with slip rings and brushes. The Brushless Doubly Fed Induction Generator (BDFIG) is an attractive choice to eliminate the drawbacks associated with slip rings and brushes. To commercialize the first BDFIG wind turbine a high performance control algorithm must be designed. This thesis focuses on the development of a control algorithm for a BDFIG based Wind Turbine Drivetrain (WTDT) system including sensorless position estimation. To explore the characteristics of the BDFIG, an equivalent circuit is developed to determine the machine steady state behavior. From the BDFIG equivalent circuit, a dynamic model of the machines is derived to form the basis for the control algorithm development. The control algorithm is based on a Field Orientated Control using a two cascaded control loops for control of active- and reactive power. WTDT reliability can be further improved by eliminating the rotor position sensor. In place of a position sensor, a method of estimating rotor position is required, such that a senorless control algorithm is achieved. Two methods for position estimation are investigated and theoretically validated. Indirect position estimation, though speed estimation, using Model Reference Adaptive System is developed and compared to direct position estimation through induced Back-Electromotive Force (B-EMF) in the stator windings. The developed sensorless control algorithm provides maximum wind power extraction during the expected operating range, where active- and reactive power control loops response are limited by mechanical inertia. The control algorithm uses the induced stator B-EMF for rotor position estimation. To test the validity of a sensorless control algorithm for a BDFIG, an experimental setup has been constructed. A sensorless current control of the Control Winding (CW) active- and reactive power has been experimentally validated, where the CW frequency is made to follow the CW stator flux. The experimental controller maintains synchronous mode of operation, for a limited speed range, due to presence of space harmonics.Electrical Power ProcessingElectrical Power EngineeringElectrical Engineering, Mathematics and Computer Scienc
Brushless Doubly Fed Induction Generator Based Wind Turbine Drivetrain Under Grid Fault Conditions
No full textWith growing interest in sustainable forms of energy, the wind industry is growing rapidly. The Doubly Fed Induction Generator is the most popular choice for the drivetrain because it is cost effective. However, it suffers from reliability and maintenance issues due to the slip rings and brushes it requires. The Brushless Doubly Fed Induction Generator (B-DFIG) aims to address these drawbacks. With increased wind power penetration, tripping of wind turbines during grid disturbances is no longer acceptable for the power system. Therefore, it is important to study the performance of such wind turbine drivetrain under low voltage events. This thesis studies the Low Voltage Ride Through (LVRT) characteristics of the B-DFIG for its application in wind turbines. This thesis first looks at the modelling and control of the Brushless Doubly Fed Induction Generator (B-DFIG) to be used in a wind turbine drivetrain. It develops the steady state model using circuit theory to study the steady state characteristics of the machine. The dynamic model is developed to form the basis of the study of the machine during low voltage events. Further, the controller is developed based on vector control. The second part of the thesis looks at the performance of a B-DFIG based wind turbine under symmetric low voltage dips. It compares the performance of this generator with that of the Permanent Magnet Synchronous Machine (PMSM) and Doubly Fed Induction Generator (DFIG) - two of the most prevalent generators used in wind turbine drivetrains today. The thesis also looks at protection methods for these generators. It has been seen that the issue with LVRT performance of the PMSM is the rise in the DC link voltage which is due to the mismatch in power generated by the machine and the power transferred to the grid. It has also been found that apart from offering better reliability through the exclusion of slip rings and brushes, the B-DFIG also has an improved LVRT performance when compared with the DFIG - the protection is simpler and can be built into the control algorithm of the machine controller.Electrical Power ProcessingElectrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc
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