Analysis of the free vibration of a coupled plate/fluid interacting system and interpretation using sub-system modal energy

This paper describes a method for describing and quantifying the vibratory behaviour of interacting structural/fluid systems based upon reference to the relative energy associated with each of the sub-systems. The particular case selected is that of a circular plate in interaction with a cylindrical fluid cavity. A theoretical analysis is performed, based upon the Euler Bernoulli and Helmholtz equations combined through a Galerkin technique, from which the natural frequencies and associated mode functions of the interacting system are calculated. The convergence of the analysis is investigated and the opportunity is taken to investigate the sensitivity of the coupled natural frequencies to different assumed mode shapes of the plate in vacuo. Subsequently the coupled mode functions are used to describe details of the energy associated with the plate and the fluid. It is found that presentation of these relative energies renders a satisfactory insight into the vibration behaviour of the coupled system

Axial vibration mode of coupled liquid-structure-gas system in a rigid cylindrical container

This paper describes the axial vibration analysis of a closed ends rigid cylindrical container containing liquid and gas which separated by a thin circular plate at their interface. The liquid depths inside the container were varied and then the mode of vibration and the natural frequencies were analyzed. The natural frequencies obtained experimentally were compared favorably with those of commercial finite element analysis software, ANSYS. The vibration mode of the liquid-structure interaction of the tank system can be visualized from the software post processing animation/plot. The visualized modes are also consistent with the measurement by the respective experimental transducers. It was found that strong coupling predominantly occur between liquid and structure. In weak coupling conditions, the modes are predominantly gas mod

Vibration analysis of a circular disc backed by a cylindrical cavity

This paper describes the free vibration analysis of a thin disc vibrating and interacting with an acoustic medium contained in a cylindrical duct. The effects of structural-acoustic coupling are studied by means of an analytical-numerical method that is based upon classical theory and the Galerkin method. The coupling effects are discussed, and results obtained from the analysis are compared with corresponding values obtained both experimentally and from a finite element analysis. There is good agreement between the three sets of results

Vibration analysis of a circular plate in interaction with an acoustic cavity leading to extraction of structural modal parameters

When carrying out vibration health monitoring (VHM) of a structure it is usually assumed that the structure is in the absence of fluid interaction and that any environmental effects which can cause changes in natural frequency either remain constant or are negligible. In certain cases, this condition cannot be assumed and therefore it is necessary to extract values of natural frequencies of the structure for the condition with no fluid interaction from those values measured. This paper considers the case of a thin circular plate in contact with a fluid cavity giving rise to strong structural/fluid vibration interaction. The paper details the free vibration analysis of the coupled system and through consideration of modal energy, illustrates how the affined modes of vibration of the plate and the fluid can be qualitatively described. The paper then introduces a method by which the natural frequencies of the plate in the absence of fluid interaction can be obtained from those of the plate in interaction with the fluid

J.R.R. Tolkien\u27s Leaf by Niggle : Word Pairs and Paradoxes

Examines Tolkien’s use of language in Tree and Leaf to “demonstrate the paradoxes inherent in Christianity [...] artistic creation [...] [and] ordinary life.” Asserts that Tolkien also “[suggests] the ultimate resolution of those paradoxes.

Lending to knowledge-based businesses in Newfoundland and Labrador

Knowledge-based businesses (KBBs) have the potential to make a significant contribution to peripheral regions with marginal economies, such as Newfoundland and Labrador. However, traditional lending approaches generally emphasize tangible collateral and historical performance. As a result, new knowledge-based firms, whose assets are primarily intangible, experience difficulty with access to financing. Financial institutions have responded by implementing specialized approaches to address the needs of KBBs. This exploratory study is designed to increase our understanding of institutional lending to KBBs, particularly at the start-up stage. Following a review of the literature a research framework was developed to explore the demand-side perspectives of entrepreneurs and the supply-side perspectives of lending institutions. A mail survey to entrepreneurs was employed to determine the roles played by chartered banks and government agencies in financing KBBs and to ascertain entrepreneurs' perceptions of financial institutions. Results indicate KBBs experience greater difficulty obtaining financing from chartered banks. Further, KBBs perceive banks to follow traditional risk assessment processes, emphasizing collateral. Findings suggest efforts by banks to cater to KBBs have been less than successful. Supply-side data were obtained from interviews with senior managers in banks and government agencies and from business plan reviews and follow-up interviews with account managers. Simultaneous verbal protocols were used to examine risk assessment processes in six banks and four government agencies. Hypothetical business proposals were presented to account mangers for initial review and subsequent due diligence. Data obtained at two stages of assessment were analyzed using consensus analysis, multidimensional scaling, hierarchical clustering, and standard multivariate techniques. Findings confirm chartered banks have establishcd specialized approaches to deal with KBBs. However, there is no evidence to indicate any differential effects on KBBs as a result of identified organizational variables. There is evidence among specialized account managers of differences in risk assessment of KBBs and of a common lending culture that reflects the needs of KBBs. Evidence of a common lending culture is also evident among traditional bankers and among government agencies that share an economic development mandate. Findings also confirm chartered banks are more concerned with financial aspects of the proposed ventures and perceived higher levels of risk than government account managers. Overall, findings provide important insights into institutional lending and have significant implications for theory, management practice and public policy. This study is one of very few to explore lending and borrowing from the perspective of KBBs and from the perspective of government agencies. Study validity is enhanced considerably by reviewing lending decisions in context and with reference to specific proposals. The use of cultural consensus theory to examine loan evaluation and risk assessment represents a significant contribution to understanding theory on lending to KBBs. Lending practices of chartered banks, while evolving to meet the needs of KBBs, have not met expectations and may need to be reexamined. Entrepreneurs in KBBs are advised to seek out KBB specialists to enhance the likelihood of obtaining financing. Government should take steps to ensure expertise is available to deal with KBBs and to encourage financial institutions, especially banks, to extend efforts to provide specialized assistance to the KBB sector. Finally, additional research is needed to confirm findings from this study and to increase their generalizability