This research is inserted in the topic of timber buildings. Many construction systems are available for building using timber, with the two main systems in residential ambit being Cross Laminated Timber and Light Timber Frame. Both systems reckon on the presence of shear walls to bear the effects of horizontal loads like seismic events or wind. This thesis deals with timber shear walls, and is divided into two parts: the first part is related to the ultimate and serviceability limit states rules to be included in upcoming versions of the building codes, while the second part presents a novel use of CLT walls as seismic renovation for existing buildings, as part of a European project. The first part of the thesis, which is presented in three papers, is closely related to the process of producing new building codes, and aims at an easier integration between research and codification. The initial focus is the behaviour of Cross Laminated Timber subjected to in-plane loading. Eurocode 5 currently lacks a part concerning this product and the discussion is still ongoing regarding the methods for stresses evaluation and on the strength values to adopt for safety verifications. The first paper tackles this problem by analysing different calculation methods currently available for the evaluation of the in-plane shear stresses, a common notation is introduced in order to have a meaningful comparison between methods proposed by different authors. All methods are then applied to a real case of existing experimental data regarding a four point bending test of CLT beams. Stiffness and strength of CLT are essential parameters for the definition of models to be adopted in codes regarding timber buildings, in particular for the calculation of shear walls. Another very common timber construction system is called Light Timber Frame: an assembly comprising a timber frame and an external sheathing layer mechanically joined to the frame. Consequently LTF walls are considered, the study is directed towards shear wall models for the evaluation of deformations. The second paper focuses on the evaluation of the displacement at the top of LTF walls subjected to horizontal loads. This is a key aspect for designers, since the limitation of deformations ensures that the building retains a satisfactory performance at serviceability limit states. The displacement is due to many different contributions, with the sheathing-to-framing deformation being one of the major ones. The paper presents a comparison between two of the proposed methods to calculate the sheathing-to-framing deformation of LTF shear walls. The influence of the nail slip contribution on the overall displacement of the top of the wall is studied also with parametric analyses, by varying both mechanical properties and geometrical dimensions. Comparison with existing experimental data is also provided. The study on shear walls regards also their lateral capacity, as well as the comparison between LTF and CLT walls of equal aspect ratio and similar restraining. In the third paper, existing cyclic test data on LTF and CLT walls were used to study the different displacement contributions and estimate the influence of the hold-down on the lateral response of the walls. A simplified capacity model is proposed for the walls, based solely on the hold-down forces. The second part of the thesis deals with the use of CLT shear walls as a mean for the retrofit of existing buildings. The need for sustainable renovation solutions and improvement of the performance of existing buildings is at the base of the European project e-Safe. The project presents a multidisciplinary approach on building renovation, from mechanical, energetic, technological and architectural point of view. In this thesis the focus is on the seismic retrofit system called e-CLT: a CLT panel is attached to the outside of existing buildings with a novel connector that acts as a friction dissipation device, thus offering additional energy dissipation in case of strong earthquakes. The fourth paper presents the first experimental campaign on this novel friction connector. Different geometries for the connector are studied and optimised, before being tested under cyclic protocol. The connector is tested on a steel setup, in order to isolate the friction behaviour and study the stability of the hysteresis loops. The results permitted to acquire new information useful for further developments on the system. The fifth paper presents a subsequent experimental campaign on the friction connector. The shape is changed and improved in light of the previous results. The setup is improved and includes also a screw connection between friction connector and CLT panel. The goal is to study the influence of the timber connection on the friction dissipative performance. An analytical model is proposed, fitted on the experimental data.

Single Wall Carbon Nanotubes (SWCNTs) are often synthesized as bundles and are chemically modified via either covalent or non-covalent approaches to prevent aggregation, improve their dispersability and tune their physical properties for a potential application. The spatial distribution and effect of covalent addends on the electronic properties of SWCNTs was characterized using a Scanning Tunneling Microscope but with limited success. The effect of sample preparation was questioned as it often involves sonicating the SWCNTs in either an organic or an aqueous medium. Sonication of SWCNTs in certain common solvents was found to alter their electronic properties. The solvent molecules are broken down via a radical pathway during sonicating leading to the formation of new species that interact with the SWCNTs and in some cases with the catalytic material present. New species such as iron chlorides and oxygen, which were formed for example in o-dichlorobenzene and water respectively, caused p-type doping. Doping was characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). A blue shift in the D* mode along with a shift to lower binding energy in the C1s peak was observed from Raman spectroscopy and XPS respectively. The reactivity of the radicals (formed during sonication) towards the structure of the SWCNTs was also investigated. Radicals formed during sonication of certain chlorinated aromatic solvents lead to the formation of sonochemical polymers, which interacted heavily with the SWCNTs. These interactions, which can be the source of features commonly associated with covalent functionalization, were thwarted by a washing protocol and were found to be non-covalent in nature. The observations are of relevance towards understanding an inadvertent chemical modification during chemical processing, which can impact reproducibility of results that involve wet-chemical processes. However, with such knowledge of the chemistry involved during sample preparation the occurrence of doping can be either circumvented or appropriately used. / Thesis / Doctor of Philosophy (PhD)

<p> A general formulation of the analysis of plane coupled shear walls is presented. The "continuous method" of analysis of coupled shear walls is reformulated in terms of deflection variables. The assumption that midpoints of the connecting beams are points of contraflexure is relaxed so that the resulting theory is applicable to the general case where the lateral loading on the piers can be arbitrarily distributed. The governing equation of the structural system under static loading with the appropriate boundary conditions are given. The effect of asymmetry of the structure is discussed. As an application of the derived theory, the problem of shear walls subjected to differential foundation settlement and rotation is studied. Solutions to deflections and internal stresses, under such conditions, are given. Evaluation of the internal stresses was performed on a practical shear wall structure and the results analysed. Through the use of deflection variables, the formulation is extended into the regime of dynamics. The governing equation of motion with appropriate boundary conditions are given. The free vibration of coupled shear walls is studied and design curves for the fundamental natural frequency are presented. The use of substitutive symmetric systems and its effects on the fundamental frequency of asymmetric systems are examined. Theoretical natural frequencies were verified by dynamic testing on two models to show that the proposed theory is sufficiently accurate to provide information for dynamic analysis in seismic design. / Thesis / Master of Engineering (ME)

<p> This study investigates the flow patterns and wall shear rate distributions downstream from a series of three glass model symmetric bifurcations, typical of the blood vessels in man. The models have a single included angle of 75° and total output to input flow area ratios of 0.75, 1.02 and 1.29, covering the physiological range. The Reynolds numbers studied (based on parent tube) were 400, 800 and 1200 in steady flow.</p> <p> Local fluid velocities were obtained at a number of axial positions along the bifurcation daughter tube via a neutrally buoyant tracer particle technique utilizing cine photography. This provided sufficient information to determine the three velocity components for each particle. The tangential and radial components were in general less than 6% of the mean axial velocity. In the case of the axial components, an analytical representation of the velocity in polar coordinates was obtained. This analytical function permits evaluation of wall shear rate distribution.</p> <p> The velocity pro£iles were found to be symmetric with respect to the plane of the bifurcation. At two diameters downstream from the carina the velocity profiles in the plane of the bifurcation showed a high peak near the inside wall of the branch. With distance downstream the peak was convected tangentially evening out the profile towards an axially symmetric mountain plateau with a dished top.</p> <p> Wall shear rate as a function of θ at constant axial position was represented by displaced cosine function. The highest shear rates always occurred on the inside wall of the daughter tube and the lowest on the outside wall. In general, the largest deviation from developed shear rates occurred close to the carina.</p> <p> The largest positive deviation in wall shear rate from developed values was found in the small area ratio bifurcation and the lowest wall shear rate value was found in the large area ratio bifurcation (a = 1.29) indicating possible flow separation near the carina. The biological implications of the shear rate information generated are discussed.</p> / Thesis / Master of Engineering (MEngr)

<p> This thesis describes the construction and testing of small-scale shear wall buildings with rigidly connected floor slabs, but without wall openings. A micro-concrete material was used in the casting of both the basic small-scale shear wall buildings and the floor slabs. The vertically cantilevered buildings were tested by applying a transverse static load at the top of the buildings.</p> <p> The behaviour of buildings with only floor slabs was compared with that of buildings containing only wall openings. The results of static loading of the buildings were compared with those results predicted analytically using Vlasov's thin-walled elastic beam theory.</p> / Thesis / Master of Engineering (MEngr)

Brick veneer / steel stud curtain wall systems have become a popular alternative in the ever competitive construction market. However, the application of such systems has preceded any formal scientific investigation into its long term serviceability and safety. Of particular interest to many parties is the performance of the wall system under typical winter conditions as would be encountered in cold climate countries such as Canada. In this study, an experimental investigation of three types of brick veneer / steel stud curtain walls was performed with a specially built apparatus used to impose air pressure, temperature and vapour pressure differentials across test specimens. In all, five wall specimens were tested for air leakage, thermal performance and moisture accumulation. An analytical investigation was also carried out with a simple, custom made finite difference computer program specially suited to determine temperature profiles in walls with a steel stud framing system. Six types of walls are evaluated with the model. A significant part of the research involved the design, construction and improvement of the test apparatus. Since the apparatus is unique, a chapter is devoted to its description. The conclusions presented indicate that certain wall designs perform poorly and that even small construction flaws can lead to serviceability problems. Conversely, care in choice and placement of the air barrier, vapour barrier and thermal insulation in the wall system can lead to a wall system that can sustain a small degree of construction errors and at the same time perform satisfactorily. It is furthermore concluded that the apparatus built for this study has real potential as a cost effective test tool suitable for adaptation for a standard test method to evaluate the environmental performance of wall systems in general. / Thesis / Master of Engineering (ME)

In the present era, with the prevailing competition, the cost of production plays a vital role. As the price of petroleum oils, especially diesel and furnace oil are growing at a steeper rate than solid fuel price, finding a substitute for furnace oil is one of the alternative available. Furnace oil used in boilers can be totally substitute by biomass with an equivalent ratio of 3.5:1 kg/liter on the basis of calorific value. This may results in saving of more than 60% of operating cost and would have attractive payback period of 6-8 months. Sri Lanka has large agriculture base and very common of having Gliricidia as an under-grow. The other biomass fuels such as paddy husk, saw dust, firewood are also available in large quantities around the country. Objective of this article is to study the conversion of presently  running furnace oil fired boiler, which is located at Ambilipitiya paper factory,Sri Lanka to biomass fired external furnace boiler namely water-wall boiler, techno economical study of the project and commissioning. Further a case study, which was done previous to this study and running successfully, is described to show the viability of the conversion using the internal furnace method. This case study was done at a Textile factory namely Brandix Finishing, Siduwa, and Sri Lanka. The results will be reducing the operating cost of the boilers and reduction of green house gas emission.  Opportunities for rural people to get extra income by farming Gliricidia, extra income from saw dust, paddy husk, and firewood are indirect benefits of the project. This report gives details of technical, environmental and commercial aspects of this unique opportunity.      Supervised by: Dr.Primal Fernando, Senior Lecturer, University of Peradeniya

Silver-gold nanocages have attracted considerable research interest recently due to their excellent performance in the fields of biomedicine and photocatalysis. These applications oftentimes manipulate at elevated temperatures and therefore impose demands on the thermal stability of the cage structures. To better understand this subject, in this work, we systematically evaluated the thermal stability of two nanocages with different wall thicknesses of 3.8 nm and 13 nm, both in the solution-phase (diethylene glycol) and solid-phase (in-situ STEM). The results revealed that the nanocages with thicker walls exhibited better thermal stabilities in both phases. By monitoring and analyzing the morphology changes of the nanocages, we determined that the nanocages with thin and thick walls undergo deformation processes differently. Nevertheless, they both deformed into more thermodynamically stable structures eventually. The plasmonic properties of the nanocages were also examined.

The discrete-element method for predicting skin friction for turbulent flow over rough surfaces considers the drag on the surface to be the sum of the skin friction on the flat part of the surface and the drag on the individual roughness elements that protrude into the boundary layer. The discrete-element method considers heat transfer from a rough surface to be the sum of convection through the fluid on the flat part of the surface and the convection from each of the roughness elements. The discrete-element method has been widely used and validated for roughness composed of sparse, ordered, and deterministic elements. Modifications made to the discrete-element roughness method to extend the validation to real surface roughness are detailed. These modifications include accounting for the deviation of the roughness element cross sections from circular configurations, determining the location of the computational "surface" that differs from the physical surface, and accounting for temperature changes along the height of the roughness elements. Two randomly-rough surfaces found on high-hour gas-turbine blades were characterized using a Taylor-Hobson Form Talysurf Series 2 profilometer. A method for using the three-dimensional profilometer output to determine the geometry input required in the discrete-element method for randomly-rough surfaces is presented. Two randomly-rough surfaces, two elliptical-analog surfaces, and two cone surfaces were generated for wind-tunnel testing using a three-dimensional printer. The analog surfaces were created by replacing each random roughness element from the original randomly-rough surface with an elliptical roughness element with the equivalent planorm area and eccentricity. The cone surfaces were generated by placing conical roughness elements on a flat plate to create surfaces with equivalent values of centerline-averaged height or root-mean-square (RMS) height as the randomly-rough surfaces. The results of the wind tunnel skin friction coefficient and Stanton number measurements and the discrete-element method predictions for each of the six surfaces are presented and discussed. For the randomly-rough surfaces studied, the discrete-element method predictions are within 7% of the experimentally measured skin friction coefficients. The discrete-element predictions are within 16% of the experimentally measured Stanton numbers for the randomly-rough surfaces.

Prediction of the near wall region is crucial to the accuracy of turbulent flow computational fluid dynamics (CFD) simulation. However, sufficient near-wall resolution is often prohibitive for high Reynolds number flows with complex geometries, due to high memory and processing requirements. A common approach in these cases is to use wall functions to bridge the region from the first grid node to the wall. This thesis presents an alternative method that relaxes the near wall resolution requirement by solving one dimensional transport equations for velocity and turbulence across a locally defined subgrid contained within wall adjacent grid cells. The addition of the subgrid allows for wall adjacent primary grid sizes to vary arbitrarily from low-Re model sizing (y+ ~ 1) to wall function sizing without significant loss of accuracy or increase in computational cost.