Soft computing based parameter identification in pavements and geomechanical systems

Accurate estimation of road pavement geometry and layer material properties through the use of proper nondestructive testing and sensor technologies is essential for evaluating pavement’s structural condition and determining options for maintenance and rehabilitation. For these purposes, pavement deflection basins produced by the nondestructive Falling Weight Deflectometer (FWD) test data are commonly used. The nondestructive FWD test drops weights on the pavement to simulate traffic loads and measures the created pavement deflection basins. Backcalculation of pavement geometry and layer properties using FWD deflections is a difficult inverse problem, and the solution with conventional mathematical methods is often challenging due to the ill-posed nature of the problem. In this dissertation, a hybrid algorithm was developed to seek robust and fast solutions to this inverse problem. The algorithm is based on soft computing techniques, mainly Artificial Neural Networks (ANNs) and Genetic Algorithms (GAs) as well as the use of numerical analysis techniques to properly simulate the geomechanical system. A widely used pavement layered analysis program ILLI-PAVE was employed in the analyses of flexible pavements of various pavement types; including full-depth asphalt and conventional flexible pavements, were built on either lime stabilized soils or untreated subgrade. Nonlinear properties of the subgrade soil and the base course aggregate as transportation geomaterials were also considered. A computer program, Soft Computing Based System Identifier or SOFTSYS, was developed. In SOFTSYS, ANNs were used as surrogate models to provide faster solutions of the nonlinear finite element program ILLI-PAVE. The deflections obtained from FWD tests in the field were matched with the predictions obtained from the numerical simulations to develop SOFTSYS models. The solution to the inverse problem for multi-layered pavements is computationally hard to achieve and is often not feasible due to field variability and quality of the collected data. The primary difficulty in the analysis arises from the substantial increase in the degree of non-uniqueness of the mapping from the pavement layer parameters to the FWD deflections. The insensitivity of some layer properties lowered SOFTSYS model performances. Still, SOFTSYS models were shown to work effectively with the synthetic data obtained from ILLI-PAVE finite element solutions. In general, SOFTSYS solutions very closely matched the ILLI-PAVE mechanistic pavement analysis results. For SOFTSYS validation, field collected FWD data were successfully used to predict pavement layer thicknesses and layer moduli of in-service flexible pavements. Some of the very promising SOFTSYS results indicated average absolute errors on the order of 2%, 7%, and 4% for the Hot Mix Asphalt (HMA) thickness estimation of full-depth asphalt pavements, full-depth pavements on lime stabilized soils and conventional flexible pavements, respectively. The field validations of SOFTSYS data also produced meaningful results. The thickness data obtained from Ground Penetrating Radar testing matched reasonably well with predictions from SOFTSYS models. The differences observed in the HMA and lime stabilized soil layer thicknesses observed were attributed to deflection data variability from FWD tests. The backcalculated asphalt concrete layer thickness results matched better in the case of full-depth asphalt flexible pavements built on lime stabilized soils compared to conventional flexible pavements. Overall, SOFTSYS was capable of producing reliable thickness estimates despite the variability of field constructed asphalt layer thicknesses.

Tourism Media Dynamics: Narratives of the Nation-State

With the premise that the tourism promotional video “China, Forever” provides a crucial access to understanding how tourism engages in a wider circle of socio-culture formation, this dissertation research approaches tourism by examining communicative practices initiated by “China, Forever”. In doing so, it seeks to reveal two dialogues – firstly, between the discursive construction of tourism representational language and China’s nation-state ideology; secondly, between interpretations from overseas Chinese audiences and nation-state narratives delivered via the tourism media. In analyzing the first dialogue, this dissertation reveals that the pursuit of collective and monolithic national imagery has caused a representational violence – one that is committed by the nation-state ideology operated through the organization of tourism language. The very representational coercion itself, however, signifies the nature of tourism media as a vehicle mediating the global gaze and China’s self-representation; illuminating the fact that China’s nation-state building is only to be understood as deeply-grounded in the complexity of postcolonial politics. Furthermore, in a dialectic view, such finding consolidates the nature of “China, Forever” as a cultural product that actively exists as a component in the overall social fabric, co-creating a wider circle of culture politics together with other genres of media products; thus, calling for a more comprehensive understanding of tourism media at large. In the second approach, this dissertation seeks to understand how the tourism video “China, Forever” mediates the relationship between tourism narratives of the nation-state and overseas Chinese individuals; thus bridging together tourism media and ongoing life experiences of the audiences chosen. The analysis reveals that audiences’ interpretations heavily concentrate on resisting and fragmenting the hegemonic nation-state language in “China, Forever”. While some interviewees seek to decentralize the nation-state perspective from aspects of aesthetics, representational style, and representational subjects in “China, Forever” by incorporating their individual memories and past experiences, to some others, the over-polished glorification of China in the mediated tourism discourse is only coercive to China’s social realities experienced by the individual interviewees - the disheartening contrasts of poverty and affluence as well as other social inequalities. From the perspective of the audience group, the Chinese scholars and students at the University of Illinois interviewed for this dissertation research constitute a cohort of exiled audiences for the tourism video “China, Forever”. The audiences subject themselves to voluntary interpellation, a process in which they find themselves defending, negotiating, and resisting the nation-state representation of China – even though they are not its intended audience and have had no input into its production. Nevertheless, such process is one of identification, in which viewers articulate a subject position from which to speak of their own experiences, dilemmas and desires. The usefulness of tourism media discourse in mediating the nation-state narratives and the individual experience is amplified.