https://www.um.edu.mt/library/oar/handle/123456789/25427 2026-04-23T12:56:24Z https://www.um.edu.mt/library/oar/handle/123456789/70808 Title: Emotional ‘design for X’ : a human and life phase systems meetings consequence knowledge approach Abstract: Throughout the various phases of its life, an evolving product meets with life phase system elements that include technical systems (e.g. fabrication machines) and human individuals (e.g. customers and factory operators). The design commitments made in relation to both the product and life phase system elements are associated with consequences that emerge from life phase system meetings. Knowledge of these consequences is of relevance to decision makers because of their impact on business metrics such as cost and time. An empirical study was carried out to address the lack of evidence on the relation between design commitments, human factory operators’ emotions and business metrics. Throughout the study, each subject was required to perform two manual assembly tasks. The emotions experienced by each subject were captured via of a questionnaire that was administered by the author. A statistical analysis established that the emotions experienced by human subjects during manual assembly, mediate the impact of design commitments on metrics such as cost and time. Furthermore the literature review established that product development decision makers lack adequate means to foresee emotional consequences and to handle the impact on business metrics. This is because design support means, such as design for manufacturing (DfM), have been intended to help designers foresee direct (D) physical consequences that emerge from life phase system meetings. Whereas design for emotion (DfE) support means focus exclusively on the emotions that customers experience when meeting with a developed product. By focusing on a single life phase, this dissertation implements and evaluates the ‘Human and Life Phase Systems Meetings’ (HLSM) consequence knowledge approach framework to emotional Design for X (eDfX). At the core of the HLSM approach framework is the knowledge model which draws inferences about direct (D) and emotional (E) consequences associated with design commitments. This knowledge guides decision makers in exploring alternative design commitments to mitigate direct (D) and emotional (E) consequences having undesirable effects on metrics such as cost and time. The HLSM approach framework has been implemented into a prototype computer-based tool named ‘Foresight of Emotional and Direct Effects’ (FEDE). The HLSM was evaluated by product development stakeholders from both industry and academia. The main contribution of this research is the HLSM approach which supports decision makers by providing knowledge of emotional consequences and their effects on business metrics. The evaluation results show that knowledge of emotional consequences and the effect on business metrics is novel and provides new decision-making opportunities. Description: PH.D 2017-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/70807 Title: Investigation of miniature lithium-bromide/water absorption refrigeration systems Abstract: Nowadays, due to the global demand for the reduction of energy usage and the use of harmful refrigerants which are associated with vapour compression refrigeration systems, alternative cooling means, like the Lithium-Bromide/Water (LiBr/H2O) absorption refrigeration system, are being investigated and produced in developed countries. However, the majority of these LiBr/H2O absorption refrigeration systems, which are available on the market, have a large cooling capacity. In fact, there is little literature related to miniature LiBr/H2O absorption refrigeration systems with small cooling capacities. This is because of the difficulties encountered during the design and operation of such systems (such as crystallization of the Lithium-Bromide/Water solution, choosing the appropriate equipment, and dimensioning of the components for compactness, etc.). Therefore, this research focuses specifically on the development of mathematical design models and experimental work that provide a successful description of the phenomenon of the absorption rate for a system with a small cooling capacity. For this reason, a miniature LiBr/H2O absorption refrigeration system equipped with an adiabatic absorber was designed and constructed, having a cooling capacity of 45 𝑊 at 10 ℃, which is also the minimum system temperature. A thermal analysis consisting of mass and energy balances was made for a range of generator and adiabatic absorber temperatures. This analysis enabled the optimum coefficient of performance (COP) to be found and recommended components’ temperatures for the absorption refrigeration system without a solution heat exchanger. The decision not to include a solution heat exchanger was taken in order to keep the system as simple as possible. Thereafter, the sizing of the system heat exchangers was made to accommodate this optimum COP and corresponding temperatures. The maximum temperature of the system was set by the generator at 80 ℃. The designed heat input in the generator was 69.2 𝑊. The design of the system and individual components is presented and explained. This includes the design of the helical coil condenser operating at 35 ℃, and the design of the adiabatic absorber operating at 30 ℃. The optimal exposed surface area of the LiBr/H2O solution to the vapour refrigerant (vapour-solution interface area) inside the adiabatic absorber was determined experimentally and found to be equal to 140 𝑐𝑚2. The most challenging part of the design was estimating the heat transfer coefficients present in the various heat exchangers. Description: PH.D 2017-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/70739 Title: Modelling the self-induced cycle-to-cycle variations in the aerodynamic blade loads of a yawed wind turbine Abstract: In the complex wind flow environment, horizontal axis wind turbines (HAWTs) experience three dimensional rotational and unsteady aerodynamic phenomena at the rotor blades sections. These highly unsteady three dimensional effects have a dramatic impact on the flow field close to a HAWT rotor, the aerodynamic load distributions on the blades, and the wake development downstream of the rotor. Unfortunately, there is still an incomplete understanding of the flow physics governing unsteady flow conditions, and hence the current theoretical models are often incapable of modelling the impact realistically. On the other hand, physical modelling of the wind turbine systems considering solely the average behaviour of the design variables and physical constants in the design process eliminates the underlining physics associated with the real dynamics of the system. These are characterised in the effects of the unstable process of dynamic stall vortex kinematics and the unsteady wake phenomena occurring in the close proximity of the rotor, amongst others. In this Ph.D. thesis, a different approach is considered for the effects of the cycle-to-cycle variations in the aerodynamic loads over multiple rotor rotations (cycles) for yawed rotors operating in a uniform and steady wind flow. This could enable new insight on modelling the direct influence of the blade on the three-dimensional flow. Description: PH.D 2017-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/29523 Title: Registration of thermographic video for dynamic temperature analysis in humans Abstract: The use of infrared thermography in medical applications has increased in popularity in recent years. It facilitates the detection and examination of skin thermal signatures, under both normal and abnormal conditions. Thermography has been employed in numerous biomedical fields, including breast cancer detection, cutaneous temperature monitoring during exercise and the analysis of normative temperature patterns. Thermal imaging may be dynamic or static in nature. Using static thermography, the steady state conditions and spatial distributions of the thermal patterns within a target are analysed at a particular instant, usually following an acclimatisation period. In contrast, via dynamic thermography, both spatial and temporal variations are considered, making the acquired data more informative. However, issues including involuntary target movement and the dynamic temperature changes undergone by the target need to be considered. Video registration was opted for in this work. Four steps constitute the registration process. The Speeded-Up Robust Features (SURF) detector was utilised in the feature detection stage. Matching features between images were then found based on the sum of squared differences (SSD) error, following which an affine geometric transformation was computed to adequately map the images in consideration. Bilinear interpolation was then utilised to calculate pixel values in non-integer coordinates. Two video registration methods were proposed in this work to address the primary issues associated with dynamic thermography. Data was gathered from nine participants for the testing of these methods. Following implementation, their performance was assessed both qualitatively and quantitatively, and a two-sample ttest was applied to verify that the difference between the mean errors per method was statistically significant. Dynamic temperature analysis was also carried out on the extracted temperature data in both the time and frequency domains, where cyclic patterns having different frequencies and magnitudes were observed across all participants. Such behaviour has not been documented in literature thus far, which implies that the biological significance of these patterns is yet to be determined. Description: B.ENG.(HONS) 2017-01-01T00:00:00Z