acase@tulane.edu

acase@tulane.edu

Currently, many cities are struggling with inner-urban blight and disjointed, divided communities due to high unemployment and lack of economic opportunity. Towns along the Mississippi River are prime examples of such distressed urban spaces, due to a combination of declining industry, lateral physical expansion away from the center and into suburbs, shifts in American revenue generators and today’s generally poor economic climate. The banks of the river are vacant with many Main Street storefronts unoccupied. Cities offer little to no waterfront commerce, entertainment or gathering – for locals and tourists alike – besides steamboat casinos. In addition, treatment of the Mississippi River is especially conservative, cautious and careful due to its strategic international importance and flood plain sensitivity; leading to the acceptance of early 20th century river control methods, with little room to engage or experience the waters. Visual and physical access to the river is denied due to levees and flood walls. However, the river embodies great potential for revitalization due to its quality resources; various fishery groups have stressed the value of aquaculture, especially for catfish cultivation, as a strong source of employment and revenue across the state of Mississippi. This thesis project seeks to investigate a sustainable model for large-scale redevelopment of decaying downtown spaces that respectfully links landscape and design while addressing problems tied to the current decline of American cities and towns. Mississippi River communities, especially in the state of Mississippi, require redevelopment with the three-fold intent of highlighting regional history, establishing an economy and providing space for the community to gather. The proposed means of re-urbanization – an urban catfish aquaculture and fishery center – prescribes an ecological, economic and productive cultural infrastructure that highlights the river and layers historical and social spaces to reinvigorate the relationship between city and its place on the water. / acase@tulane.edu

This thesis studies topology optimization method employing the homogenization method, with a focus on different microstructures and their effects on the topology optimization solutions. In the thesis, different microstructure models were investigated. The strengths and weaknesses of each type of microstructures were discussed. Homogenization method was employed to formulate the homogenized properties of the material. The optimality criteria and schemes of updating the design variables in the topology optimization process were derived for the newly developed microstructures and existing microstructures for which the information is not available in the literature. New microstructure models of one-material and bi-material were established. Based on these studies, a computer software package called Homogenization with Different Microstructures (HDM) incorporating fifteen existing and the new microstructure models was developed. By using the software, a series of problems were studied and solutions given by different microstructure models were compared.

Multi-layered corrugated fibreboard, has in recent years been gaining attention as a replacement for polymeric materials for protective packaging for environmental reasons. The properties of pre-compressed multi-layered corrugated fibreboard make it a sustainable replacement for poly-foam and polystyrene. Pre-compressed multilayered fibreboard cushions have most of the structural resistance and damping removed, and the properties of air-flow through the flutes becomes a more predominant, they behave more like a soft spring. Artificially restricting the exiting airflow or prudently choosing the direction of flutes in the case of rectangular cushions, allows for the differing design situations that may be required. A mathematical model is developed, to describe the pre-compressing process. Mathematical models and software are developed, based on the airflow characteristics, that allow for the prediction of peak acceleration for differing end conditions or sizes providing the friction component can be estimated using iterative methods. The models were verified by a static compression test for the pre-compression and by dropping a mass, or platen and recording the resistive acceleration, or dynamic behaviour, over a time range. There exists an acceleration component prior to platen contact, which is also modelled and should be considered in the interpretation of test results. The study has presented three models to allow for the prediction of the behaviour of multi-layered corrugated fibreboard for the use as protective cushions. The main thrust has been the behaviour of the airflow during and prior to impact whilst testing. The models developed will assist in the design of protective packaging and produce predictive tools for the use in the packaging industry.

The essential characteristic of controllable fluids is their ability to change their rheological behaviour under an electrical field. These materials are referred as Electro-Rheological (ER) fluids. An ER fluid is a mixture of a base fluid, usually some type insulating liquid such as mineral or silicone oil, with suspension particles, such as cornstarch, zeolite, glass bead or cellulose. When there is no electric field, particles are randomly suspended in the base liquid. When an electric field is applied, the particles in the fluid form chains bridging the conductors of opposite polarity and turn the liquid into a solid-like gel. The process is seemingly reversible once the electric field is removed. The process takes place within milliseconds. In this thesis, shear and valve modes of operation are considered for one particular ER fluid from a practically oriented design point of view. Chapter 1 provides background information concerning ER fluids and ER devices in practical applications. Chapter 2 describes a prediction tool for the shear mode of operation based on the Bingham model. The prediction model is based on the (solid to liquid) weight fraction, applied electric field and strain rate. An ER clutch with a single disk was designed, and tested to validate the model. In Chapter 3, an ER valve experiment is presented to relate the force-displacement behaviour with varying applied voltage, weight fraction and other operating conditions (volume flow rate, cyclic frequency and stroke length). A new model for an ER damper in fluctuating flow is also presented in Chapter 4. This new model is a modification of the uniform flow Bingham plastic model. Comparison between the predictions from the model and observations from the experiments is also given in Chapter 4. In Chapter 5, an overview is given of this work’s contribution and future work is discussed.

Next generation wireless modems are likely to be based on multiple antenna hardware platforms, following the demand for high data rate. In correlated channels Channel State Information (CSI) at the transmitter provides a significant capacity increase over conventional Multiple Input Multiple Output (MIMO) systems. In such a case, the Singular Value Decomposition (SVD) of the channel matrix gives the optimal precoder and decoder. This thesis studies the performance of the SVD architecture under varying propagation environments, as well as its robustness to various impairments, e.g. incorrect channel estimation, hardware errors. The aim is to provide a comprehensive understanding of the advantages and weaknesses of the SVD-based transmission architecture.

Like other engineering structures, buried stormwater drainage pipes deteriorate and fail over time in terms of pipe collapses due to structural deterioration or pipe blockages due to hydraulic deterioration. The deterioration of service infrastructure was a concern in Australian in recent times, where stormwater drainage pipes in Australia were rated as ‘poor condition’. The information on current and future condition of stormwater pipes is therefore important for making decisions on when and how to carry out maintenance and rehabilitation. As the major objective, this study attempted to develop separately structural and hydraulic deterioration models that can predict the condition changes of pipe population and condition changes of individual pipes as compared to the ‘like-new’ condition. The outcomes of the models can be used for planning annual budget and prioritizing repairs. Furthermore, this study aimed to identify the significant factors that affect the structural and hydraulic condition of stormwater pipes, which could support design and operation of stormwater pipes. To achieve these objectives, this study first considered an ideal deterioration model which recognized that pipes deteriorate differently due to their contributing factors such as pipe size and soil type. Based on the ideal deterioration model, five practical deterioration models were developed using statistical techniques and neural networks (NNs), and were calibrated using different optimization techniques in searching for the best suitable model. These deterioration models were selected considering the availability of snap-shot (or once only) inspection data and the ordinal grading system of pipe condition. The model inputs were contributing factors and the model output was pipe condition in ordinal numbers. Methods for assessing the predictive performance of these models and determining the significant input factors were considered. A case study with data collected from a City Council in Melbourne (Australia) was used to demonstrate the applicability of the models developed in this study. The results showed that the NN model and the Markov (statistical) model were the best models for predicting condition changes of individual pipes and pipe population respectively. Several factors such as pipe size and pipe location were found significant factors in these models. The significance of this study is the development of deterioration models that provide a basis for the construction of a comprehensive asset management system for stormwater pipes. The major innovation of this study is the exploitation of advanced modelling techniques for predicting the deterioration process of stormwater pipes.

Floods are one of the most costly types of natural disasters in Australia and other parts of the world. It was reported that the average annual cost of flood damage in Australia was about $300 million as at 1994. However, the effects of flooding can be mitigated, and thereby reduce the loss of life and damage to property. Flood mitigation measures can be categorised into two groups. The first group, the structural measures, involves civil works in the flood plain and/or catchment. The second group, the non-structural measures, includes flood forecasting, flood warning and emergency planning, planning controls and acquisition of flood prone land within the catchment, and providing flood insurance to affected people. The flood damage mitigation in the catchment or basin depends on complex social, economical and environmental conditions. It is not always feasible to completely control or manage flood damage through structural measures due to economic, technological, environmental and social constraints. Therefore, non-structural measures such as flood forecasting and warning often play an important role in minimizing flood damage, especially, when there are no feasible structural measures that can be implemented. While planning, design, construction and operation of most structural measures can be done using definite mechanisms, the decisions of non-structural measures, especially flood forecasting and warning, are complex and are not uniquely defined. Therefore, such decisions require the aid of mathematical model results, and require both quantitative and qualitative decision modelling steps. Thus, these decisions can be effectively obtained through the use of a Decision Support System. The Decision Support Systems (DSSs) have recently become popular in making decisions related to complex water resource problems. However, the design and the development of some of these applications do not contain all essential elements of a modern-day DSS, such as effective databases and file management facilities, user-friendly interfaces, appropriate simulation models, spatial and graphical data display and analysis modules, and facilities for effective decision making. Moreover, the theory of DSS and computer science has developed rapidly since the initial development of some of these applications. Furthermore, only a few applications of DSS in flood control and warning exists in the literature. These applications cited in the literature mostly deal with planning aspects of flood control, and not real-time flood forecasting and warning. Therefore, considering the above facts, it is timely and necessary to develop an effective DSS to facilitate decision making of flood warning using all recent advances in DSS theory and computer science, and combining all necessary and desirable elements of a DSS into one system. The Maribyrnong River basin is a medium size catchment located in the northwest of Melbourne in Victoria, Australia. Its low-lying flood plains along the lower sections of the river have been frequently being inundated by floods. A flood warning system has been established in 1975 after a major flood in 1974 to minimise flood damage in the lower part of the catchment. This system uses several numerical models such as the RORB model and the HEC-2 model for flood forecasting. However, there is no single computer-based system that integrates these models to facilitate analysis of different scenarios in controlling and managing the flood damage, and in making objective and effective decisions. Furthermore, the use of these separate models is time consuming and can lead to errors in transferring information from one model to another. Therefore, a computer-based DSS for flood forecasting and warning in the Maribyrnong River basin would enhance the effectiveness of flood warning in this catchment. As part of this research, the author has defined the DSS as an interactive computer-based system that helps decision-makers to use data and models to solve semi-structured problems effectively. This DSS should allow the user to participate in principal steps of the decision making process, to simulate many steps in the process of decision making, to investigate alternative scenarios, to seek the overall goal for decision, and to improve the effectiveness of decision making. The author also suggested a DSS in water resources, which in most cases deals with spatial data display and analysis, should include five essential components: a database subsystem, a modelbase subsystem, an interface subsystem, a decision support subsystem, and a spatial and graphic data display and analysis subsystem. Most previous research work on DSS development, especially in the area of water resources do not give details of the conceptual system design and details of the subsystems. This thesis provides the details of the conceptual system designs of all subsystems and their major functions. These approaches will help further system development of the DSS of this thesis. The general concept used in this thesis can be used for DSS studies in other water resource studies and in other fields. Based on well-designed system, a unique decision support system, DSSFCMR (Decision Support System for Flood Control in the Maribyrnong River basin) was developed in this thesis to help decision making in flood forecasting and warning from data entry to search of final decisions. The DSSFCMR consists of five subsystems, namely Database Management System (DBMS), Modelbase, Spatial and Graphic Data Display and Analysis (SGDDA), Decision Support, and Interface. The DSSFCMR can consider various forecast rainfall depths in three different forecast periods. The developed Database subsystem can perform various tasks for database management related to flood warning. The URBS hydrological and HEC-RAS hydraulic models in the Modelbase subsystem are used to calculate flood hygrographs and corresponding flood water levels along the flood prone area respectively. Based on the calculated water levels, the shapefile for flood inundated area is instantly created, which is then used for spatial analysis of the flood inundated area through the developed interactive map interface. Two separate methods were developed in the SGDDA subsystem to perform spatial data display and analysis of the flood inundated area for use by different users (with different computer skills) and/or for organizations with different levels of resources. The process of complicated data transfer within DSSFCMR (e.g. the peak discharge to the flood water level, then flood water level to the shapefile of flood area) is automated by the developed system functions. The technology developed for decision choice support in this study helps to locate the required scenarios from many scenario results using the database technology. All functions are properly integrated together for the benefit of the user to make the decisions effectively. The use of DSSFCMR to provide decision support for flood forecasting and warning in the Maribyrnong River basin was illustrated. The application was on the flood event that occurred on 04 October 1983, but under 1997 topographical conditions. Essentially, the application concentrated on flood forecasting and warning decisions at a particular time during the event. The system effectively performed calibration of the URBS and HEC-RAS models, forecasting of flood hydrographs, calculation of flood water levels, spatial data display of flood inundated areas and decision selection support for flood warning at this particular time. Generally, the developed system DSSFCMR can efficiently forecast flood hydrographs and calculate the flood water levels; the process of complex data transfer is done automatically and quickly; the data can be displayed flexibly in various formats; the system is easy to use by different users with different computer skills; the user can use DSSFCMR to investigate decision making variables related to flood warning (e.g. people relocation) conveniently and quickly. In summary, this system helps the decision maker to make the decisions in relation to flood forecasting and warning in the Maribyrnong River basin effectively.

The world’s water resources are rapidly deteriorating due to the combined effects of global warming, climate change, population growth and fast development, posing new challenges to water resources managers. Conflicting objectives and expectations of various stakeholders have led to increasing interests in the consideration and resolution of multiple social, economic, environmental and supply sustainability objectives in the management of water supply systems, especially during extended dry periods. This study attempted to develop and assess the potential of a generic decision support framework to assist in evaluating alternative operating rules for multi-purpose, multireservoir urban water supply systems. The multi-objective outranking approach which facilitated the incorporation of stakeholder preferences in the decision making process is a main focus area in this research. The main elements of the framework are illustrated on a case study of the Melbourne water supply system, demonstrating its capabilities for evaluating alternative operating rules under single or group decision-making situations. Eight performance measures (PMs) were identified under four main objectives to evaluate the system performance related to sixteen pre-selected alternative operating rules. Three major stakeholder groups, namely, resource managers, water users and environmental interest groups were represented in hypothetical decision making situations. An interviewerassisted questionnaire survey was used to derive stakeholder preferences on PMs in terms of preference functions and weights as required by the PROMETHEE/GAIA method and its computer software tool Decision Lab 2000. A total of 97 personnel selected from Melbourne Water and Victoria University participated in the survey expressing their preferences on the eight PMs. Finally, an overall ranking for alternative operating rules is obtained together with other output results, which focused on the best compromises between the objectives considered. The method yields reliable and robust results in terms of varying group compositions considered in the case study. The major innovation of this project is the development of a transparent and intuitive multi-objective decision support framework that has potential to be developed for evaluating alternative operating rules for urban water supply systems.