Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains xi, 137 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 119-126).

Thesis (M.Eng.(Electrical Engineering))--University of Pretoria, 2001. / Summaries in Afrikaans and English. Includes bibliographical references.

Thesis supervisor: Andrew Kusiak. Includes bibliographic references (p. 112-119).

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 164-173). Also available on the World Wide Web.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed May 22, 2007). PDF text:xviii, 204 p. : ill. (some col.) ; 2.37Mb UMI publication number: AAT 3237050. Includes bibliographical references. Also available in microfilm and microfiche formats.

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This thesis considers the development of a Hammerstein-bilinear approach to non-linear systems modelling, analysis and control systems design, which builds on and extends the applicability of an existing bilinear approach. The underlying idea of the Hammerstein-bilinear approach is to use the Hammerstein-bilinear system models to capture various physical phenomena of interest and subsequently use these for model based control system designs with the premise being that of achieving enhanced control performance. The advantage of the Hammerstein-bilinear approach is that the well-structured system models allow techniques that have been originally developed for linear systems to be extended and applied, while retaining moderate complexity of the corresponding system identification schemes and nonlinear model based control designs. In recognition of the need to be able to identify the Hammerstein-bilinear models a unified suite of algorithms, being the extensions to the simplified refined instrumental variable method for parameter estimation of linear transfer function models is proposed. These algorithms are able to operate in both the continuous-time and discrete-time domains to reflect the requirements of the intended purposes of the identified models with the emphasis being placed on straightforward applicability of the developed algorithms and recognising the need to be able to operate under realistic practical system identification scenarios. Moreover, the proposed algorithms are also applicable to parameter estimation of Hammerstein and bilinear models, which are special cases of the wider Hammerstein-bilinear model class. The Hammerstein-bilinear approach has been applied to an industrial heating, ventilation and air conditioning (HVAC) system, which has also been the underlying application addressed in this thesis. A unique set of dynamic control design purpose oriented air temperature and humidity Hammerstein-bilinear models of an environmentally controlled clear room manufacturing zone has been identified. The greater insights afforded by the knowledge of the system nonlinearities then allow for enhanced control tuning of the associated commercial HVAC control system leading to an improved overall control performance.

Heating, ventilation and air-conditioning (HVAC) systems are widely distributed over the world due to their capacity to adjust some local climate parameters, like temperature, relative humidity, cleanliness and distribution of the air until the desired levels verified in a hypothetical ideal climate. A review of buildings’ energy usage in developed countries shows that in the present this energy service is responsible for a portion of about 20% of the final energy usage on them, increasing up to 50% in hot-humid countries. In order to decrease this value, more and more different heat recovery systems have been developed and implemented over the last decades. Nowadays it is mandatory to install one of these units when the design conditions are above the limit values to avoid such components, what is possible to verify mostly in non-residential buildings. Each one of those units has its own performance and working characteristics that turns it more indicated to make part of a certain ventilation system in particular. Air-to-air energy recovery ventilation is based on the heat recovery transfer (latent and/or sensible) from the flow at high temperature to the flow at lower temperature, pre-warming the outdoor supply air (in the case of the winter). Therefore, it is important to understand in which concept those units have to be used and more important than that, how they work, helping to visualize their final effect on the HVAC system. The major aims of this study were to investigate the actual performance of the heat recovery units for LB20 and LB21 in building 99 at the University of Gävle and make some suggestions that could enhance their actual efficiency. Furthermore, the energy transfer rates associated to the heat recovery units were calculated in order to understand the impact of such components in the overall HVAC system as also the possible financial opportunity by making small improvements in the same units. To assess the system, values of temperature and flow (among others) were collected in the air stream and in the ethylene-glycol solution that works as heat transfer medium between air streams and is  enclosed in pipes that make part of the actual run-around heat recovery units. After some calculations, it was obtained that for the coldest day of measurements, the sensible effectiveness was 42% in LB20 and 47% in LB21, changing to 44% and 43% in the warmer day, respectively. The actual heat transfer representing the savings in the supply air stream is higher on the coldest day, with values of 46 kW in LB20 and 84 kW in LB21, justifying the existence of the heat recovery units even if those ones imply the use of hydraulic pumps to ensure the loop. The low values of efficiency have shown that both heat recovery units are working below the desired performance similarly to the pumps that make part of the same units.  This fact, together with the degradation of the units that is possible to observe in the local, indicates that a complete cleaning (followed by a change of the heat transfer medium) of the heat recovery units and a new adjustment of pumps and valves for the further changes, are necessary. By doing this, it is expected to see the year average sensible effectiveness increase to close to 45% in both units which will lead to a potential economic saving of around 41 000 SEK per year.

Peak electricity demand in South Africa will exceed the available operational generation capacity in 2007. The state utility Eskom is addressing this challenge, inter aha, with the implementation of the Demand-side Management (DSM) initiative. The aim of DSM is to defer the building of additional power stations by modifying the end-user pattern to reduce electrical load during the morning and evening peaks. At the end of 2005 the DSM programme has only achieved 30°/o of its target. Some of the biggest problems are the lack of knowledge on how to perform ESCO audits and availability of tools and procedures to enable Energy Service Companies (ESCOs) to evaluate DSM potential. Studies in South Africa have shown that 20°/o of the total municipal energy is utilised in commercial buildings. Additional investigations have shown that in the commercial sector approximately 50% of energy is used for air conditioning. Energy savings of around 30% can be realised through improved management procedures and retrofit projects of HVAC systems of existing buildings. Telecommunication companies own and operate a large portfolio of diverse buildings. It was shown that these buildings are very inefficient in terms of energy usage. Performing ESCO analyses on these building portfolios present huge savings opportunities for the building owners as well as load reduction opportunities to help meet DSM targets. ESCOs however face major problems in evaluating DSM projects on telecommunication facilities. Some of these problems are: time to perform the ESCO audits on such a large portfolio of buildings; skill levels of available personnel; lack of experience and structured audit process; availability of information; data capturing of information; determining the impact of the retrofits and calculating the savings and financial benefits of retrofits. Obtaining approval for DSM projects is also a lengthy process. Smaller ESCOs cannot afford to commit resources to ESCO investigations only to recover their investment after project approval. Having an ESCO procedure that will speed up the audit process will help the ESCO to minimise resources that need to be committed to these investigations. Having a tested and reliable ESCO procedure will also help Eskom since they will receive more and better quality DSM proposals. A new ESCO procedure for telecommunications facilities was developed. The primary requirements for the new ESCO procedure are that it should be simple, stable, fast and accurate. This procedure is evaluated against the known energy management opportunities in telecommunication facilities. Some of the benefits of the new ESCO procedure are: time taken to perform ESCO analysis on all types of buildings is drastically reduced; lower qualified personnel can be used to perform the ESCO analysis; any type of HVAC system configuration can be accommodated; new data capturing procedures ensure that only essential data is captured; integrated simulation software is used that can easy and accurately simulate the building operations and retrofits on a building; retrofit options suitable for telecommunication facilities are identified; contribution to the DSM programme is evaluated; financial evaluation of the retrofits and feasibility for DSM funding and results are integrated into a standardised reporting format. The new ESCO procedure was implemented on several case studies within the telecommunication infrastructure. Five different types of buildings were selected to implement the ESCO procedure. Each step of the procedure was evaluated and tested against the requirements of the new ESCO procedure. It was proven through implementation that the new ESCO procedure is successful in solving the unique problems in performing ESCO analyses for telecommunications facilities. Valuable insight into the problems that can occur during the ESCO process was highlighted, and recommendation for future work was presented. / Thesis (Ph.D. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2006.

Thesis (Ph.D. (Electrical Engineering))--North-West University, Potchefstroom Campus, 2006.