A research program was designed to investigate the characteristics of three-dimensional laminar wall jet flow of both Newtonian and two shear-thinning non-Newtonian fluids. The non-Newtonian fluids were prepared from xanthan gum solutions of various concentrations. Both experimental and numerical methodologies were employed in this study. The wall jet was created using a circular pipe of diameter 7 mm and flows into an open fluid tank. The initial Reynolds numbers based on the pipe diameter and jet exit velocity ranged from 250 to 800. The velocity measurements were conducted using a particle image velocimetry technique. The measurements were conducted at several streamwise locations to cover both the developing and self-similar regions. For the numerical study, the complete nonlinear Navier-Stokes equation was solved using an in-house colocated finite volume based CFD code. A Carreau model was employed for the non-Newtonian fluids. The viscosity in the governing equations was obtained explicitly. From the PIV measurements and CFD results, velocity profiles and jet half-widths were extracted at selected downstream locations to study the effects of Reynolds number and specific fluid type on the jet characteristics. It was observed that the numerical results are in reasonable agreement with the experimental data. The decay of maximum velocity, jet spread rates, skin friction coefficient, streamwise velocity profiles, and secondary flows depend strongly on the initial Reynolds number irrespective of the fluid. The results also show that the jet spreads more in the spanwise direction than in the transverse direction in the early flow development whereas the reverse is true in the downstream region. Important differences were observed when the results for the non-Newtonian fluids were compared with those for Newtonian fluid.

The primary objective of this research program was to investigate the effective modulus of elasticity and shear modulus of brick masonry walls under lateral load, and to to justify using the Jaeger and Mufti method to calculate the effective modulus of elasticity and shear modulus of brick masonry walls. The experimental program involved the testing of three unreinforced brick masonry walls under in-plane and vertical loads. Linear Variable Differential Transducers were used to record the horizontal and vertical displacements of the walls. The experimental results were used to evaluate the modulus of elasticity and the shear modulus of walls under flexure. The experimental results were compared to the finite element analysis results. It was found that the finite element analysis yields similar results to the experimental results. It was also found that the Jaeger and Mufti method to calculate effective modulus of elasticity and shear modulus of brick masonry walls is effective for design purposes.

The research focusses on computational analysis of vortex generation behind A-Pillar of simplified model derived from Jaguar XF that excludes air from the underside of vehicle. This vortex formation contributes in generating wall pressure fluctuations especially at speeds higher than 100km/hr. It is a collaborative work between Cranfield University and Jaguar Land Rover. Three dimensional pressure based incompressible flow using Large Eddy Simulation turbulence model is selected for computational analysis in FLUENT v14. This used high parallel computing systems available in Cranfield University. In the initial phase, three grid resolutions (coarse, medium and fine) were prepared in ICEM CFD with fine case consisting of 10 million cells. Qualitative analysis includes extraction of slices, 3-D and surface streamlines and pressure and velocity contours for capturing the unsteadiness due to the vortex formation over the front side glass surface. The iso-surface of Q captures the unsteadiness at the A-Pillar wake and side mirror wake over front side glass surface. It also reveals that the range of length scales captured were limited even at the finest grid resolution. Quantitative analysis compares the mean pressure (Cp) data with JLR results. Probes were located at 51 locations over the front side glass window that showed a good comparison; specifically for the fine grid; with maximum variation incurred at probes located in separation areas. For predicting the wall pressure fluctuations, a total of ten probes were located over the front side glass window surface. The surface pressure (static) data was recorded for 1 sec of flow-time and later imported in MATLAB for post-processing. The results obtained in 1/3rd octave band showed that the large scales were too energetic and small scales are not captured. However, comparing sound pressure levels with the Aero-acoustic Wind Tunnel (AWT); provided by JLR; it is concluded that either the grid is too coarse to resolve higher frequencies or the numerical modelling used is too dissipative to benefits the use of LES.

The reversed-field pinch (RFP) is a device for magnetic confinement of fusion plasmas. The main objective of fusion plasma research is to realise cost-effective thermonuclear fusion power plants. The RFP is highly unstable as can be explained by the theory of magnetohydrodynamics (MHD). Feed-back control technology appears to enable a robustly stable RFP operation.  Experimental control and identification of nonaxisymmetric multimode MHD is pursued in this thesis. It is shown that nonparametric multivariate identification methods can be utilised to estimate MHD spectral characteristics from plant-friendly closed-loop operational input-output data. It is also shown that accurate tracking of the radial magnetic field boundary condition is experimentally possible in the RFP. These results appear generically useful as tools in both control and physics research in magnetic confinement fusion. / <p>QC 20120508</p>

The blood is a complex fluid that contains, in addition to water, cells, macro-molecules and a large number of smaller molecules. The physical properties of the blood are therefore the result of non-linear interactions of its constituents, which are influenced by the local flow field conditions. Hence, the local blood viscosity is a function of the local concentration of the blood constituents and the local flow field itself. This study considers the flow of blood-like fluids in generalised 90-degree bifurcating pipes and patient-specific arterial bifurcations relevant to the large aortic branches in humans. It is shown that the Red Blood Cell (RBC) distribution in the region of bifurcations may lead to large changes in the viscosity, with implications on the concentrations of the various cells in the blood plasma. This in turn implies that the flow in the near wall regions is more difficult to estimate and predict than that under the assumption of a homogeneous fluid. The rheological properties of blood are complex and are difficult to measure, since the results depend on the measuring equipment and the inherent flow conditions. We attempt to model the viscosity of water containing different volume fractions of non-deforming RBC-like particles in tubes. The apparent viscosities of the mixtures obtained from these model experiments have been compared to the predictions of the different rheological models found in the literature. The same rheological models have also been used in the different simulations, where the local RBC concentration and local shear rate are used in the viscosity models. The flow simulations account for the non-linearity due to coupling between the flow and fluid rheology. Furthermore, from a physiological perspective, it is shown that oscillatory wall shear stresses are affected by changes in RBC concentration in the regions of the bifurcation associated with atherogenesis. The intrinsic shear thinning rheological property of the blood, in conjunction with stagnation in separated flows, may be responsible for elevated temporal wall shear stress gradients (TWSSG) influencing endothelial cell behaviour, which has been postulated to play a role in the development of atherosclerosis. The blood-like fluid properties along with variations in the RBC concentration could also lead to variations in the developing flow structures in the larger arteries that could influence the work the heart has to bear. / <p>QC 20131206</p>

Mielių (Saccharomyces cerevisiae) taikymas biologiniuose jutikliuose ar biokatalizėje ribojamas jų ląstelės sienelės struktūros, kuri apsunkina reikiamų medžiagų transportą. Todėl darbo tikslas – ištirti mielių ląstelių mechaninių savybių ir plazminės membranos bei sienelės pralaidumo pakitimus, veikiant mielių ląsteles cheminėmis medžiagomis bei mikro- ir nanosekundžių trukmės didelės galios impulsais naudojant atominių jėgų mikroskopą bei tetrafenilfosfonio katijonų elektrocheminę analizę. Nustatyta, kad ditiotreitolis (DTT) keisdamas mielių sienelių pralaidumą, pakeičia mielių ląstelių mechanines savybes. Esant didelėms deformacijoms mielių ląstelių tamprumo modulis (Young‘o) padidėjo nuo 1,00 ± 0,04 MPa nepaveiktoms iki 2,14 ± 0,1 MPa DTT paveiktoms mielėms. Tiriant impulsinio elektrinio lauko (IEL) poveikį mielių sienelės pralaidumui, impulso trukmių nuo mikrosekundžių iki nanosekundžių diapazone stebima tiesinė TPP+ absorbcijos greičio priklausomybė nuo impulso energijos. Nustatyta, kad veikiat mieles 60 ns trukmės impulsais ląstelių pralaidumas TPP+ molekulėms, nepažeidžiant mielų gyvybingumo, padidėjo iki 65 kartų lyginant su nepaveiktomis elektriniu lauku mielių ląstelėmis, t.y. 3,5 karto daugiau negu mieles paveikus 150 μs impulsais. Tyrimų rezultatai rodo, kad IEL galima didinti visos ląstelės biologinių jutiklių spartą ir atrankumą. / The application of yeast (Saccharomyces cerevisiae) in the biosensors or in the biocatalysis is limited due to the structure of their cell walls, which complicates the transport of necessary materials. The aim of this work was to investigate the mechanical properties of the yeast cells and the changes of permeability of cell plasma membrane and cell wall, after the impact of chemical compounds on the cell wall permeability and after their exposure of pulsed electric field (PEF) in the range from microsecond till nanosecond pulse duration. For analysis the atomic force microscopy and the electrochemical detection of tetraphenylphosphonium ions were used. Dithiothreitol (DTT) modifies the yeast cell wall permeability changing the mechanical properties of the cells and for high indentations Young modulus increasing from 1.00 ± 0.04 MPa for intact cells to 2.14 ± 0.1 MPa for DTT treated ones. The linear relation between TPP+ absorption rate and pulse energy was determined after investigations of PEF effect to the yeast cell permeability in the range of pulse duration from microseconds to nanoseconds. The obtained 65 time increase of yeast cell wall permeability to TPP+ molecules after the exposure of 60 ns PEF, which does not affect the cell viability, comparing with the intact yeast cells. Such permeability increment was 3.5 times higher in comparison to the yeast cells exposure to 150 µs duration PEF. The finding can be useful for the enhancement of selectivity and response of... [to full text]

The application of yeast (Saccharomyces cerevisiae) in the biosensors or in the biocatalysis is limited due to the structure of their cell walls, which complicates the transport of necessary materials. The aim of this work was to investigate the mechanical properties of the yeast cells and the changes of permeability of cell plasma membrane and cell wall, after the impact of chemical compounds on the cell wall permeability and after their exposure of pulsed electric field (PEF) in the range from microsecond till nanosecond pulse duration. For analysis the atomic force microscopy and the electrochemical detection of tetraphenylphosphonium ions were used. Dithiothreitol (DTT) modifies the yeast cell wall permeability changing the mechanical properties of the cells and for high indentations Young modulus increasing from 1.00 ± 0.04 MPa for intact cells to 2.14 ± 0.1 MPa for DTT treated ones. The linear relation between TPP+ absorption rate and pulse energy was determined after investigations of PEF effect to the yeast cell permeability in the range of pulse duration from microseconds to nanoseconds. The obtained 65 time increase of yeast cell wall permeability to TPP+ molecules after the exposure of 60 ns PEF, which does not affect the cell viability, comparing with the intact yeast cells. Such permeability increment was 3.5 times higher in comparison to the yeast cells exposure to 150 µs duration PEF. The finding can be useful for the enhancement of selectivity and response of... [to full text] / Mielių (Saccharomyces cerevisiae) taikymas biologiniuose jutikliuose ar biokatalizėje ribojamas jų ląstelės sienelės struktūros, kuri apsunkina reikiamų medžiagų transportą. Todėl darbo tikslas – ištirti mielių ląstelių mechaninių savybių ir plazminės membranos bei sienelės pralaidumo pakitimus, veikiant mielių ląsteles cheminėmis medžiagomis bei mikro- ir nanosekundžių trukmės didelės galios impulsais naudojant atominių jėgų mikroskopą bei tetrafenilfosfonio katijonų elektrocheminę analizę. Nustatyta, kad ditiotreitolis (DTT) keisdamas mielių sienelių pralaidumą, pakeičia mielių ląstelių mechanines savybes. Esant didelėms deformacijoms mielių ląstelių tamprumo modulis (Young‘o) padidėjo nuo 1,00 ± 0,04 MPa nepaveiktoms iki 2,14 ± 0,1 MPa DTT paveiktoms mielėms. Tiriant impulsinio elektrinio lauko (IEL) poveikį mielių sienelės pralaidumui, impulso trukmių nuo mikrosekundžių iki nanosekundžių diapazone stebima tiesinė TPP+ absorbcijos greičio priklausomybė nuo impulso energijos. Nustatyta, kad veikiat mieles 60 ns trukmės impulsais ląstelių pralaidumas TPP+ molekulėms, nepažeidžiant mielų gyvybingumo, padidėjo iki 65 kartų lyginant su nepaveiktomis elektriniu lauku mielių ląstelėmis, t.y. 3,5 karto daugiau negu mieles paveikus 150 μs impulsais. Tyrimų rezultatai rodo, kad IEL galima didinti visos ląstelės biologinių jutiklių spartą ir atrankumą.

As a result of concern about the effects of CO2 emssions on the global warming, there is increasing pressure to reduce such emissions from power generation systems. The use of biomass co-firing with coal in conventional pulverised fuel power plants has provided the most immediate route to introduce a class of fuel that is regarded as both sustainable and carbon neutral as it produces less net CO2 emissions. In the future it is anticipated that increased levels of biomass will be required to use in such systems to accomplish the desired CO2 emissions targets. The use of biomass, however, is believed to result in severe fireside corrosion of superheater and reheater tubing and cause unexpected early failures of tubes, which can lead to significant economic penalties. Moreover, future pulverised fuel power systems will need to use much higher steam temeptures and pressures to increase the boiler efficiency. Higher operating temperatures and pressures will also increase the risk of fireside corrosion damage to the boiler tubing and lead to shorter component life. Predicting the remaining service life of superheater and reheater tubes in coal-biomass fired power plants is therefore an important aspect of managing such power plants. The path to this type of failure of heat exchangers involves five processes: combustion, deposition, fireside corrosion, steam-side oxidation, and creep. Various models or partial models each of these processes are available from existing research, but to fully understand the impact of new fuel mixtures (i.e. biomass and coal) and changing operating conditions on such failures, an integrated model of all of these processes is required. This work has produced an integrated set of models and so predicted the remaining service life of superheater/reheater tubes based on the three frameworks which have been developed by analysing those models used in depicting the five processes: one was conceptual and the other two were based on mathematical model. In addition, the outputs of the integrated mathematical models were compared with the laboratory generated data from Cranfield University as well as historical data from Central Electricity Research Laboratories. Furthermore, alternative models for each process were applied in the model and the results were compared with other models results as well as with the experimental data. Based on these comparisons and the availability of models constants the best models were chosen in the integrated model. Finally, a sensitivity analysis was performed to assess the effect of different model input values on the residual life superheater and reheater tubing. Mid-wall metal temperature of tubes was found to be the most important factor affecting the remaining service life of boiler tubing. Tubing wall thickness and outer diameter were another critical input in the model. Significant differences were observed between the residual life of thin-walled and thick-walled tubes.

In this thesis, wall-resolved and wall-modeled large-eddy simulation (LES) have been employed to investigate turbulent flow and dispersion around a single and a group of wall-mounted bluff bodies which are partially and fully submerged in developing boundary layers, respectively. The dispersion is caused by a continuous release of a passive scalar from a ground-level point source located within the matrix of obstacles. The results have been validated through comparisons against the available experimental measurement data. Thorough physical analysis including investigation of the spatial evolution and temporal cascades of the kinetic and scalar energies, flow structures and their influences on dispersion of the concentration plume in the context of highly disturbed flows, and study of turbulence statistics for the flow and concentration fields have been performed to provide deeper insights into turbulent flow and dispersion in domains with complex geometries. An in-house code based on FORTRAN programming language, parallelized with MPI libraries has been developed, modified and optimized for conducting the simulations. The simulations have been conducted on public-domain supercomputers ofWest-Grid, specifically Orcinus and Grex, and also the local 256-core cluster system of the CFD LAB at the University of Manitoba.

Several nucleoside natural product antibiotics from Streptomyces sp. and actinomycetes have recently been shown to target bacterial peptidoglycan cell wall biosynthesis by inhibiting the bacterial translocase I (MraY). The biosynthetic gene clusters for A-90289, liposidomycins and caprazamycins revealed a protein with sequence similarity to proteins annotated as α-KG:taurine dioxygenases (TauD). This enzyme (LipL) is a mononuclear, non-heme, Fe(II) dependent α-keto glutarate (α-KG) :uridine monophosphate (UMP) dioxygenase responsible for the net dephosphorylation and two electron oxidation of UMP to uridine-5’-aldehyde. The postulated reaction coordinates involving the activation of the C-5’ center in UMP and the corresponding formation of uridine-5’-aldehyde are modeled on extensive spectroscopic and structural characterizations of TauD. In this dissertation, the postulated radical mechanism for LipL involving the formation of an unstable hydroxylated intermediate is investigated via the characterization of a key product obtained from the reaction of LipL (and its homolog Cpr19) with a synthetically modified surrogate substrate where the bridging phosphoester oxygen in UMP is replaced with a 5’ C-P bond. We further validate our hypothesis by analyzing the reactions of both LipL and Cpr19 with specifically 2H1 – labeled UMP substrate and confirming the expected products via mass spectrometry. In addition, we explore substrate promiscuity of the enzymes and utilize a set of site specific mutants of Cpr19 as means of gaining better insight into the active site residues. Predictive models for Cpr19 and LipL structures are developed by the combination of experimental results and chemical logic.