Rational Function Interpolation of Electromagnetic Transfer Functions of High-Speed Interconnect Systems from Discrete Time-Domain and Frequency-Domain Data

We present new methodologies to generate rational function approximations of broadband electromagnetic responses of linear and passive networks of high-speed interconnects, and to construct SPICE-compatible, equivalent circuit representations of the generated rational functions. These new methodologies are driven by the desire to improve the computational efficiency of the rational function fitting process, and to ensure enhanced accuracy of the generated rational function interpolation and its equivalent circuit representation. Toward this goal, we propose two new methodologies for rational function approximation of high-speed interconnect network responses. The first one relies on the use of both time-domain and frequency-domain data, obtained either through measurement or numerical simulation, to generate a rational function representation that extrapolates the input, early-time transient response data to late-time response while at the same time providing a means to both interpolate and extrapolate the used frequency-domain data. The aforementioned hybrid methodology can be considered as a generalization of the frequency-domain rational function fitting utilizing frequency-domain response data only, and the time-domain rational function fitting utilizing transient response data only. In this context, a guideline is proposed for estimating the order of the rational function approximation from transient data. The availability of such an estimate expedites the time-domain rational function fitting process. The second approach relies on the extraction of the delay associated with causal electromagnetic responses of interconnect systems to provide for a more stable rational function process utilizing a lower-order rational function interpolation. A distinctive feature of the proposed methodology is its utilization of scattering parameters. For both methodologies, the approach of fitting the electromagnetic network matrix one element at a time is applied. It is shown that, with regard to the computational cost of the rational function fitting process, such an element-by-element rational function fitting is more advantageous than full matrix fitting for systems with a large number of ports. Despite the disadvantage that different sets of poles are used in the rational function of different elements in the network matrix, such an approach provides for improved accuracy in the fitting of network matrices of systems characterized by both strongly coupled and weakly coupled ports. Finally, in order to provide a means for enforcing passivity in the adopted element-by-element rational function fitting approach, the methodology for passivity enforcement via quadratic programming is modified appropriately for this purpose and demonstrated in the context of element-by-element rational function fitting of the admittance matrix of an electromagnetic multiport.

Wildlife as a Priority in Park Development: A Study of Illinois Park Professionals

The purpose of this thesis is to consider the factors that impact decision making in city park settings, with specific emphasis given to wildlife. Additionally, professional bias was considered as a possible response determinant. Studies connecting perceptions of wildlife and Illinois park managers have been rare or nonexistent, but offer the potential for the improvement of management strategies and recreational opportunities. Data was collected using mixed methods. City recreation practitioners statewide were invited to complete a self-administered questionnaire considering wildlife as a decision-making factor in land acquisition or restoration decisions. A small follow-up sample of park managers was interviewed via telephone for further explanation of their response. Analysis of responses from questionnaires and interviews suggested that wildlife habitat is a factor in land use decision making, but is not considered one of the highest importance. Respondents identified that nuisance wildlife, access to wildlife, and public value of wildlife were also factors in decision making. Factors associated with a high-ranking of the importance of wildlife were agencies with a high number of natural area acres, a high number of overall park acreage, personnel devoted to natural area management, the presence of hiking trails, and cities with a large population. Professional bias of recreation managers was suggested via anecdotal interview data, but could not be empirically connected with wildlife-related decision-making processes, as no managers identified themselves as having completed formal wildlife-related training. As a result, management implications include separate training for both practitioners and public. This study broadens the understanding of wildlife management in city park settings, and reaffirms that further understanding of public and pracitioner values of wildlife will lead to improved land use decisions and recreationally valuable experiences.