Thesis (Ph. D.)--Drexel University, 2005. / Includes abstract and vita. Includes bibliographical references (leaves [165]-180).

Detailed flow measurements made in a 1 metre diameter, shrouded, centrifugal (Ghost) impeller running at 500 rpm are presented. Relative velocities and rotary stagnation pressures $(p*=p-\frac{1}{2}\ρω^{2}r^{2}+\frac{1}{2}\ρW^{2})$ were measured on five cross-sectional planes between the impeller inlet and the outlet, using probes which were traversed within the rotating impeller passage. The reduced static pressures $(p_{r} = p-\frac{1}{2}\ρω^{2}r^{2})$, calculated from the flow measurements, are also presented. Measurements were made in a 'design' flow (approximately zero incidence at the blade leading edge), a 'below design' flow and an 'above design' flow. A wake flow was observed in all three flows and there were two major sources of the wake fluid. Firstly, from the separation of the shroud boundary layer and secondly, from the accumulation of low p* fluid from the other boundary layers by secondary flows. The results showed that the wake's position at the outlet moved from the suction side in the 'below design' flow, to the suction-side/shroud corner region in the 'design' flow and to the shroud in the 'above design' flow, because of the change in the relative strengths of the secondary flows generated by rotation and curvature. The modifications to turbulent mixing, by curvature and rotation, probably influenced the wake size. In order to predict the wake's location at the impeller discharge, a simple secondary flow model, which represented the impeller as a pipe bend, was devised. This model was successfully tested on two analytically soluble flows, in a stationary bend and in a rotating straight pipe. The model was then used for the more complex flows in a rotating axial-to-radial bend and in the Ghost and Eckardt's centrifugal impellers. The theoretical results for these impellers showed several of the features observed in the flow measurements.

In this study, the deformation and fracture behavior of short glass fiber reinforced thermoplastics are examined. Emphases are given to the roles of fiber reinforcements on thermoplastic matrices with varying ductility. The results indicate that in the amorphous matrices of SAN and ABS composites, the addition of glass fibers does not influence the morphology of the matrix materials. In the semi-crystalline matrix of nylon 6,6, however, the glass fiber reinforcements are found to reduce the spherulite size and lower composite's matrix crystallinity. The tensile properties of a short glass fiber reinforced thermoplastics are found to be more influenced by glass fibers than by the matrix ductility. The fracture toughness of the thermoplastic composites, on the other hand, are found to depend both on the glass fiber reinforcement and on the matrix ductility. In this study, the toughness dependence is further separated into two stages of crack initiation and crack propagation. In the crack initiation stage, the initiation toughness of a thermoplastic composite strongly depends on its matrix ductility. In the crack propagation stage, the propagation toughness of a thermoplastic composite is found to be dominated by matrix ductility and by fiber/matrix interfaces. The fracture and toughening mechanisms of a glass fiber reinforced thermoplastic composites are found to relate to the deformation mechanisms of the matrix, to the fiber-matrix interactions, and to the fiber-fiber interactions. In the brittle SAN composite the fracture occurs by debonding and void formation at fiber ends. In the rubber toughened ABS composites, the fracture at crack tip is associated with the matrix crazing deformation at larger rubber particles and is facilitated by the void formation at fiber ends. In the nylon 6,6 composites, on the other hand, the fracture mechanism is strongly associated with fiber-fiber interactions and the observed toughening mechanism is resulted from enhanced matrix crystallographic shear plasticity due to stress field interactions of nearby glass fiber ends. A strong relationship between the fracture toughness, fracture mechanisms, and microstructures are also observed in thermoplastic composites. The fracture toughness parameters, J-integral toughness or $K\sb{IC}$ values, are therefore microstructure sensitive and can be used to provide general guidance of toughness improvement in thermoplastic composites. (Abstract shortened by UMI.)

Doctor of Philosophy (PhD)

<p>The project report examines the design criteria and procedures currently used in the design of sanitary sewer systems. A review of literature concentrates on procedures for the automated design of sanitary sewer systems. From the literature review, it is concluded that the cost optimisation of a variable layout together with details of sewer sizes and vertical alignment is not practicaI.</p> <p>The major part of the project is the development of a program which employs dynamic programming in a multi-pass mode to optimise the cost of a branched sanitary sewer system of fixed layout. The program permits some user flexibility by allowing options for defining cost data and design criteria. Detailed documentation for operating the program is provided. A critical appraisal of the effectiveness of the algorithm and a comparison with other programs which use the dynamic programming technique is presented: A measure of the sensitivity of the optimal policy to changes in the cost structure is examined.</p> / Master of Engineering (ME)

<p>The project aims at developing a method to be used for the inelastic analysis of single span composite beams. As an integral part of the project, a computer program is also presented, which works for both shored and unshored beams with or without cover plate for symmetrical loading cases. After successful testing of the program against experimental results, computations were performed to determine the lower limit to the degree of partial connection permissible in practical composite beams.</p> / Master of Engineering (ME)

<p>A research program is presented to analyse the behaviour of the T-joints between square (or rectangular) HSS in the elastic range. An attempt was made to obtain the joint rigidity in both cases of loading, applied moment and branch member axial loads.</p> <p>Two different joint types were analysed, unreinforced T-joint as well as the haunch reinforcement type. In each case, the chord top flange was considered as a thin pIate loaded on the perimeter of a rigid inclusion.</p> <p>A theoretical model was established for the chord member to describe the continuity between the top flange plate with the chord webs, and to permit the introduction of elastically restrained edges for deflection as well as rotation.</p> <p>The finite difference method was used together with a variety of edge boundary conditions to study the effect of the width ratio λ, the haunch size parameter λ₁ and the width-thickness ratio b/t.</p> <p>The joint stiffness values (axial and bending) were obtained theoretically for 80 different joint sizes with 5 different edge conditions for the chord plate. A comparison with the available experimental and other theoretical results is also presented.</p> <p>The main contribution in the study was the theoretical analysis presented for the haunch type connection, which has not been done previously.</p> <p>An elastic stress analysis was also conducted to define limits for the working loads that may be applied to the joints without incurring yielding in the chord member.</p> <p>The theoretical study confirms the results of tests that the unequal width unreinforced connection is generally too weak to be viable practically. However, the haunch connection, while not as "aesthetically attractive as the unreinforced type, has adequate strength and stiffness for most applications.</p> / Master of Engineering (ME)

<p>In any given health care system where the incidence of disease is high and the outcome poor, the process of care should be examined to determine changes that can be made, which will lead to improved outcome. The hypothesis to be tested in this study is that carefully designed and administered continuing education programme for nurses will improve the process of care and improve the outcome in critically ill children who have been hospitalized because of measles, meningitis or tetanus. In other words, improved nursing education improve's quality of care. This thesis presents a randomized controlled trial to test the hypotheses.</p> <p>Issues in quality of care and quality assurance are discussed. An in-service education programme is developed for nurses who have no pediatric special case training but, because of shortage of medical personnel, are depended upon heavily to make judgements about care of critically ill infants.</p> <p>This educational programme is based on pathophysiological states which are designated indicator based on pathophysiological conditions. The quality of care studies done before and after the educational programme are based on nurses' management of infants with these indicator conditions. The use of pathophysiological states rather than specific diseases allows for a greater number of pediatric patients to be managed by nurses who have this in-service training since most of the infants admitted into the hospitals develop one or any combinations of these morbid states.</p> <p>A general hospital setting is chosen for this study for greater generalizability of the results since most of these infants are cared for in general hospitals; only a negligible number compared to the high incidence are admitted into teaching hospitals.</p> <p>To reiterate: the main questions that this thesis seeks to answer are:</p> <p>1. Did the nurses learn?</p> <p>2. Did they change their practice behaviour?</p> <p>3. If (1) and (2) had occurred, did the patients' health outcome change?</p> / Master of Engineering (ME)

<p>The object of this investigation is to establish a method of determining the locus of centres of rigidity of an asymmetric multi-story building structure, which can be applied to determine, with acceptable accuracy, the shear forces in the load-resisting panels in a static or dynamic analysis.</p> <p>Based on a more general definition for the centre of rigidity within a particular story of a multi-story building structure, a method is developed for the evaluation of the locus of centres of rigidity of a multi-story building structure. Other existing methods are also discussed. It has been found that the locus of centres of rigidity is not only a function of the structural properties but also a function of the distribution of lateral forces acting on the multi-story building structure. It has also been shown that for a building structure consisting of panels which are disproportional in stiffness, the traditional method (in which only the structural elements in an isolated story is considered for the determination of the centre of rigidity within that story) do not give a satisfactory estimation of the locus of centres of rigidity.</p> <p>The applicability of the locus of centres of rigidity to the evaluation of the shear forces in the load-resisting panels in a static, analysis is investigated. Based on the results of this investigation, methods of determining the panel shear forces in a static analysis are recommended for various types of building structures.</p> <p>The applicability of the locus of centres of rigidity to the evaluation of the panel shear forces in a dynamic analysis using a three degree-of-freedom model is also studied. The results of this study show that the distribution of the panel shear forces in a frame building structure obtained by using the model, agrees well with that obtained by using a three-dimensional dynamic frame program. The model can only provide a rough estimation of the magnitude of the panel shear forces.</p> / Master of Engineering (ME)

<p>In seismic analysis of buildings it is usual to consider planar models along each of the two principal axes, and to independently analyze the response of each model to the in-plane horizontal component of ground motion. Analysis on this basis is strictly valid only for structures with coincident centers of mass and rigidity. The lateral and torsional motions are coupled if the centers of mass and rigidity do not coincide.</p> <p>It is the purpose of this thesis to consider the torsional effect in the seismic analysis of one-story buildings and to illustrate the effect of the lateral-torsional coupling on their response.</p> <p>A mathematical model for a torsionally coupled one-story building is developed considering the effect of eccentricity between the center of mass and the center of resistance. The coupled analysis is then investigated for excitation due to several different earthquakes.</p> <p>The second object of this study is to develop a simple procedure, which provides a convenient means to obtain conservative estimates of earthquake forces in a special class of torsionally coupled systems.</p> / Master of Engineering (ME)