Optimized synthesis of cost-effective, controllable oil system architectures for turbofan engines

Turbofan oil systems are used to provide lubrication and cooling in the engine . There is an increasing interest in oil system architectures which utilize electric pumps and/or valves to give optimized control of flows to individual oil chambers, leading to improved thermal management of oil and lubrication efficiency. The challenges here lie in the trade-off between increasing controllability and minimizing the addition of new components, which adds unwanted production and maintenance costs. This paper formulates the oil system architecture design as a constrained, multiobjective optimization problem. An architecture is described using a graph with nodes representing components and edges representing interconnections between components. A fixed set of nodes called the architecture template is provided as an input and the edges are optimized for a multicriteria objective function. A heuristic method for determining similarities between the different oil chamber flow requirements is presented. This is used in the optimization to evaluate the controllability objective based on the structure of the valve architecture. The methodology provides benefits to system designers by selecting cheaper architectures with fewer valves when the need to control oil chambers separately is small. The effect of manipulating the cost/controllability criteria weightings is investigated to show the impact on the resulting architecture

The analysis of the peculiarities of spouses relationships during the transition to parenthood

This research aims at identifying the factors that determine the peculiarities of the relationship between spouses during the transition to parenthood and revealing the changes in their relationship after the birth of the first child. The research was carried out in two stages: in the last trimester of pregnancy and after three or four months after the birth of a child. The questionnaire compiled by Kalicki, Peitz (1995) was applied in the first stage of the research. The questionnaire contained the following scales: pregnancy evaluation scale, the scale on confidence in their competence and control and the scale on sharing daily duties. The scale on the quality of couple‘s relationship (Kalicki, Hahlweg, 1992) was given to the respondents in order to evaluate the relationship between spouses. The questionnaire contained also three subscales measuring communication, tenderness/sexuality and conflicting situations in the relationship of spouses. It was also used Self-perception scale (Kalicki, Peitz, 1995). The following two scales were used in the secondary research: the scale on the allotment of daily duties (Kalicki, Peitz, 1995) and the scale on the quality of couple‘s relationship. 40 spouses, aged from 19 to 43, took part in this research. 15 couples out of 40 couples researched took part in the second state of the survey. The research was carried out on couples that were married, living together, expecting the first child and the woman was in her third pregnancy trimester. The following general conclusions could be drawn on the basis of the results obtained in the present research. Firstly, the research shows that those couples which reacted with great joy on the news about pregnancy gave higher value to the relationship itself, respondents who reacted with a great boast on pregnancy news appreciated tenderness/sexuality more than the relationship itself, while the relationship was given the lowest value by the couples whose reaction on the pregnancy was negative. Secondly, the study revealed that spouses that are emotional and optimistic give higher value to relationship rather than those couples that are flexible as they give more attention to tenderness and sexual relations. Thirdly, it became evident that the more traditional way of sharing daily duties, the lower is evaluation of the relationship between partners. The traditional way of sharing everyday duties changes, however, after the birth of the first child. Finally, the research shows that partners evaluate their relationship as worse after the birth of the first child, while men consider the relationship with their spouses then as deteriorationg and becoming more conflicting

Eliminating Design Alternatives under Interval-Based Uncertainty

Typically, design is approached as a sequence of decisions in which designers select what they believe to be the best alternative in each decision. While this approach can be used to arrive at a final solution quickly, it is unlikely to result in the most-preferred solution. The reason for this is that all the decisions in the design process are coupled. To determine the most preferred alternative in the current decision, the designer would need to know the outcomes of all future decisions, information that is currently unavailable or indeterminate. Since the designer cannot select a single alternative because of this indeterminate (interval-based) uncertainty, a set-based design approach is introduced. The approach is motivated by the engineering practices at Toyota and is based on the structure of the Branch and Bound Algorithm. Instead of selecting a single design alternative that is perceived as being the most preferred at the time of the decision, the proposed set-based design approach eliminates dominated design alternatives: rather than selecting the best, eliminate the worst. Starting from a large initial design space, the approach sequentially reduces the set of non-dominated design alternatives until no further reduction is possible ??e remaining set cannot be rationally differentiated based on the available information. A single alternative is then selected from the remaining set of non-dominated designs. In this thesis, the focus is on the elimination step of the set-based design method: A criterion for rational elimination under interval-based uncertainty is derived. To be efficient, the criterion takes into account shared uncertainty ??certainty shared between design alternatives. In taking this uncertainty into account, one is able to eliminate significantly more design alternatives, improving the efficiency of the set-based design approach. Additionally, the criterion uses a detailed reference design to allow more elimination of inferior design sets without evaluating each alternative in that set. The effectiveness of this elimination is demonstrated in two examples: a beam design and a gearbox design.M.S.Committee Chair: Chris Paredis; Committee Member: Bert Bras; Committee Member: Leon McGinni

MARC 266/7 Research Overview

Presentation given for SRL meeting Summer 200