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Aerospace systems are complex systems with interacting disciplines and technologies. As a result, the Decision Makers (DMs) dealing with such problems are involved in balancing the multiple, potentially conflicting attributes/criteria, transforming a large amount of customer supplied guidelines into a solidly defined set of requirement definitions. A variety of existing decision making methods are available to deal with this type of decision problems. The selection of a most appropriate decision making method is of particular importance since inappropriate decision methods are likely causes of misleading engineering design decisions. The research presented in this dissertation proposes a knowledge-based Multi-criteria Interactive Decision-making Advisor and Synthesis process (MIDAS), which can facilitate the selection of the most appropriate decision making method and which provides insight to the user for fulfilling different preferences. Once the most appropriate method is selected for the given problem, the advisor is also able to aid the DM to reach the final decision by following the rigorous problem solving procedure of the selected method. The MIDAS can also provide guidance as to the requirements needed to be fulfilled by a potentially new method for cases where no suitable method is found. In many other domains, such as complex system operation, decisions are often made in an environment with continuously changing situations. In addition, the decisions are usually completed based on uncertain or incomplete information due to the data availability and the environmental variation. This fact exacerbates the complexity of the decision making process because it results in the difficulties in perfectly and deterministically reasoning about the effects of the decisions and thus make it hard in determining the further decisions. In order to make proper decision and increase the system’s effectiveness, an advanced decision strategy is needed to capture the system’s dynamic characteristics and environmental uncertainty. An autonomous decision making advisor is developed to perform the real-time decision making under uncertainty. The development of the advisor system aims to solve a resource allocation problem to redistribute the limited resources to different agents under various scenarios and try to maximize the total rewards obtained from the resource allocation actions.

With the rapid advancement of technologies, software is gaining its popularity in assisting our daily activities in the last decades. This circumstance causes a rising concerns about a software product with high quality which lead to a question about the justification whether a software product has high quality. Therefore, a numerous of researches and studies had spent a lot of effort in software product quality assessment in order to justify whether the software product(s) under study have satisfactory quality. One of the foremost approaches to assess software product quality is the application of the quality models. For example, quality model ISO 9126. However, the quality models do not provide an explicit way to aggregate the performance of different quality aspects nor handling the various interests raised from different perspective or stakeholders. Although many studies have been conducted to aggregate the different measures of quality attributes, they are still not capable to include the various interests raised by different software product stakeholders. Therefore, some studies have attempted to apply MCDA methods in order to aggregate the measure of quality attributes as the ultimate software product quality and handling the various quality interests. However, they do not provide any rational about their particular choice of MCDA methods. Most of them justify their choice by referring to high popularity of the selected MCDA method. Without studying the suitability of MCDA methods in the application domain of the software product, it is difficult to conclude whether the chosen MCDA methods fit in the intended software engineering discipline. Furthermore, there is no systematic approach available to help other software practitioners in selecting the MCDA method that will be suitable for their needs and constraints in software product quality assessment. This thesis aims to provide the key concepts for an effective selection of suitable MCDA method for the purpose of software product quality assessment. A foremost part of this thesis presents two systematic reviews. The first review illustrates the evaluation of the characteristics of MCDA methods. The second review identifies the major needs and constraints of the software quality assessment potential MCDA method has to consider in order to be used for assessing quality of software products. Based on the results from both systematic reviews, a selection framework named MCDA-SQA framework is formulated. This framework is intended to assist the software practitioners to systematically select and adapt appropriate MCDA method(s) in order to fulfil their quality assessment needs and the respective environmental concerns.

Major challenges concerning climate change are facing the world and action needs to be taken by the entire society to prevent serious consequences. Contaminated sites are another wide spread environmental and health issue and the need for remediation is great. Unfortunately, remediations often cause high climate impact due to many and long transports, as well as other factors, in order to treat or deposit the contaminated soil. The purpose of this study was to investigate if and how Swedish municipalities take the climate issue into consideration when selecting a soil remediation method and to identify factors that could increase the climate consideration. To accomplish this, a survey was created and directed to the departments of land and exploitation, in 276 municipalities of Sweden. The results showed that it was not very common to set goals concerning limited climate impact or to calculate it. Rather many deposit contaminated soil and rather many also think that more climate friendly remediation techniques could lead to equal risk reduction. Increased technical feasibility and increased knowledge, as well as increased guidance on risk balancing and changed requirements from authorities, were most often believed to have the highest potential of increased climate consideration. Cost and time consumption were often limiting factors. Conclusions were that the development of sustainable remediation techniques needs to continue. Also, authorities are suggested to offer more guidance as well as a more holistic approach in order for the remediation sector to better meet climate goals.

In recent years, the requirements engineering community has proposed a number of models for the generation of a well-formulated, complete set of requirements. However, these models are often highly abstract or narrowly focused, providing only pieces of structure and parts of guidance to the requirements generation process. Furthermore, many of the models fail to identify methods that can be employed to achieve the activity objectives. As a consequence of these problems, the requirements engineer lacks the necessary guidance to effectively apply the requirements generation process, and thus, resulting in the production of an inadequate set of requirements. To address these concerns, we propose the expanded Requirements Generation Model (x-RGM), which consists of activities at a more appropriate level of abstraction. This decomposition of the model ensures that the requirements engineer has a clear understanding of the activities involved in the requirements generation process. In addition, the objectives of all the activities defined by the x-RGM are identified and explicitly stated so that no assumptions are made about the goals of the activities involved in the generation of requirements. We also identify sets of methods that can be used during each activity to effectively achieve its objectives. The mapping of methods to activities guides the requirements engineer in selecting the appropriate techniques for a particular activity in the requirements engineering process. Furthermore, we prescribe small subsets of methods for each activity based on commonly used selection criteria such that the chosen criterion is optimized. This list of methods is created with the intention of simplifying the task of choosing methods for the activities defined by the x-RGM that best meet the selection criterion goal / Master of Science