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In a typical light metal building, the structural members are designed for the forces and moments obtained from the wind drift analysis, which assumes pinned connections at the base. The pinned connections provide no moment at the base and have zero rotational stiffness. However, in reality every connection provides some restraint and has some rotational stiffness. Hence, by considering a modeling assumption of pinned condition, the actual behavior of the connection is not captured and this results in overestimation of lateral drifts and appearance of larger moments at the knee of the gable frames. Since the structural components are designed on the basis of these highly conservative results, the cost of the project increases. This thesis investigates the real behavior of the column base connection and tries to reduce the above stated conservatism by developing a computer program or "wizard" to calculate the initial rotational stiffness of any column base connection. To observe the actual behavior of a column base connection under different load cases, a number of finite element models were created in SAP2000. Each finite element model of the column base connection contained base plate, column stub, anchor bolts and in some cases grout as its components. The model was mainly subjected to three load cases, namely gravity, wind and gravity plus wind. After performing many analyses, the influence of flexibility of each component on the flexibility of the connection was observed and a list of parameters was created. These parameters are the properties of above mentioned components which characterizes any column base connection. These parameters were then used as inputs to model any configuration of the column base connection in the developed wizard. The wizard uses OpenSees and SAP2000 to analyze the modeled configuration of the connection and provides values of the initial rotational stiffness and maximum bearing pressure for the provided loads. These values can be further used in any structural analysis which is done to calculate the lateral drift of a frame under lateral loads. This will also help in getting results which are less conservative than the results which one gets on assuming pinned condition at the base. / Master of Science

Measurement of dynamic/transient torques is important in the dynamic analysis of rotating machinery as it provides insight into the internal state of the machine. Existing methods are difficult to implement, results are not obtained in real-time and are not very accurate. This thesis introduces a new method of determining real-time dynamic torque. An optical encoder is used to sense motion at a convenient point in the rotating system containing the rigid shaft of interest. The encoder's output is processed digitally to yield angular velocity, acceleration and dynamic torque. Two different experiments were conducted to demonstrate the advantages of this new method of determining dynamic torque over conventional methods. In one experiment, an extension spring was mounted on a crank arrangement coupled to a fractional horsepower motor to apply a periodic load to the system. A mathematical model of this dynamic system was developed to compare the results of this model with that of the instrumentation system. In another experiment, the instrumentation system was used on an existing motor-compressor system. The dynamic torque thus determined was again compared with the results of a simulation program. In both the above experiments the evaluated dynamic torque and computed dynamic torque were within 5% of each other, demonstrating accuracy and reliability of this personal computer based dynamic torque determining system. / Master of Science

No / The torsional response of rotor systems comprising bearings, inertia discs, and relatively long, slim shafts is considered. Lumped, finite element and hybrid, distributed-lumped parameter procedures are employed to represent the rotor systems of concern in efforts aimed at increasing accuracy, integrity, and computational efficiency. Rotor, shaft, and bearing elements of arbitrary dimensions, constructed from materials with differing mechanical properties, can be accommodated within the system models formulated. General results for multiple rotor assemblies are derived. Simple computational techniques are employed to obtain the frequency response and time domain characteristics for the models proposed. Analytical validation of the resonance conditions identified is provided. Application studies are presented for purposes of comparison.

<p> The level structure of the Odd-A nucleus 163Lu has been studied by the 148Sm (19F,4n) 163Lu reaction through gamma-ray singles and gamma-gamma coincidence methods.</p> <p> A number of rotational band structures have been observed up to a spin of 43/2. The backbending behaviour of the two signatures of the h11/2 band, α = -1/2 and α = 1/2, has been observed. The critical frequencies for the backbends are wc = 0.264 and 0.284 respectively.</p> / Thesis / Master of Science (MSc)

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<p> The foaming process has received increased attention by the rotational molding industry in recent years. The use of metallocene catalyzed polyethylenes for producing a cellular structure is a new development in rotational molding. The objective of this work was to investigate the effects of different chemical blowing agents, resin properties and processing conditions on the structure of foamed metallocene polyethylene and obtain a fundamental understanding of the parameters governing the foam structure and part properties.</p> <p> An experimental study was conducted to produce metallocene polyethylene foams in dry-blending-based rotational foam molding. The physical and cell structure properties of the final foamed parts were examined. The critical processing parameters that optimize the foam structure have been identified through adjustments to the molding conditions.</p> <p> The foaming performance of exothermic and endothermic chemical blowing agents were examined and it was revealed that selecting an appropriate chemical blowing agent was crucial as the foam structure depends significantly on the properties of the blowing agent. Exothermic blowing agents resulted in greater foam density reduction compared to endothermic blowing agents.</p> <p> The effect of rheological properties on the foaming process and foam properties was also examined. Rotomolding experiments were performed in monolayer and skin-foam moldings. Observations indicated that the final foam properties were profoundly influenced by the rheological properties of the polymer materials. There was a good correlation between the foam properties produced in both monolayer and two layer moldings. It was discovered that polymer materials with higher extensional viscosity could provide a promising foaming performance at different processing conditions.</p> <p> The effect of the surface tension of the polymer materials was investigated. It was found that type of reaction of the blowing agent (exothermic/endothermic) and composition of gas generated determine whether the surface tension of the resin contributes to the trend of changes in foam properties.</p> / Thesis / Master of Applied Science (MASc)