Many applications are migrating or beginning to make use native XML data. We anticipate that queries will emerge that emphasize the structural semantics of XML query languages like XPath and XQuery. This brings a need for an efficient query engine and database management system tailored for XML data similar to traditional relational engines. While mapping large XML documents into relational database systems while possible, poses difficulty in mapping XML queries to the less powerful relational query language SQL and creates a data model mismatch between relational tables and semi-structured XML data. Hence native solutions to efficiently store and query XML data are being developed recently. However, most of these systems thus far fail to demonstrate scalability with large document sizes, to provide robust support for the XPath query language nor to adequately address costing with respect to query optimization. In this thesis, we propose a novel cost-driven XPath engine to support the scalable evaluation of ad-hoc XPath expressions called VAMANA. VAMANA makes use of an efficient XML repository for storing and indexing large XML documents called the Multi-Axis Storage Structure (MASS) developed at WPI. VAMANA extensively uses indexes for query evaluation by considering index-only plans. To the best of our knowledge, it is the only XML query engine that supports an index plan approach for large XML documents. Our index-oriented query plans allow queries to be evaluated while reading only a fraction of the data, as all tuples for a particular context node are clustered together. The pipelined query framework minimizes the cost of handing intermediate data during query processing. Unlike other native solutions, VAMANA provides support for all 13 XPath axes. Our schema independent cost model provides dynamically calculated statistics that are then used for intelligent cost-based transformations, further improving performance. Our optimization strategy for increasing execution time performance is affirmed through our experimental studies on XMark benchmark data. VAMANA query execution is significantly faster than leading available XML query engines.

Existe uma noção intuitiva de que os custos associados a ações de suporte de projetos de gerenciamento de Tecnologia da Informação (TI), muitas vezes considerados já muito elevados e em crescimento, possuem forte vinculação com esforços empreendidos nas fases de desenvolvimento/implantação e teste. Apesar da importância de caracterizar e compreender a sistemática dessa relação, pouco tem sido feito neste domínio, principalmente devido à falta de mecanismos adequados tanto para o compartilhamento de informações entre as fases de um projeto de TI, quanto para aprender com experiências passadas. Para lidar com essa problemática, propõe-se nesta dissertação uma abordagem para estimar dinamicamente os custos de suporte de projetos de gerenciamento de TI à luz de informações provenientes das fases de desenvolvimento/implantação e teste. As estimativas de custos são calculadas a partir da integração de informações produzidas ao longo do ciclo de vida de projetos (passados). O núcleo da solução presente neste trabalho conta com um modelo Bayesiano para realizar previsão de custos de suporte, apoiado em um modelo de informação usado para persistir informações históricas. Para provar conceito e viabilidade técnica da solução proposta considerou-se, como estudo de caso, a predição de custos associados com projetos de implantação de infraestrutura de redes sem fio. Durante a avaliação é demonstrada a eficácia e eficiência do modelo, bem como discutido suas potencialidades e limitações para auxiliar no entendimento do compromisso entre custos de desenvolvimento/ implantação, teste e suporte. A avaliação conduzida fez uso de dados reais/sintéticos produzidos a partir de projetos do ISBSG e apresenta resultados próximos dos encontrados em cenários reais. Nossa abordagem obteve cerca de 80% de acerto na estimativa dos custos de suporte para os cenários avaliados. / There is an intuitive notion that the costs associated with IT management project support actions, often deemed extremely high and increasing, are directly related to the effort spent during their development/deployment and test phases. Despite the importance of systematically characterizing and understanding this relationship, little has been done in this realm mainly due to the lack of proper mechanisms for both sharing information between IT project phases and learning from past experientes. To tackle this issue, in this dissertation we proposed an approach for dynamically predicting IT management project support costs taking into account information gathered from the development/deployment and test phases. Support cost estimates are computed by integrating existing information from the lifecycle of (past) projects. The core of the solution in this work relies on a Bayesian model to perform support cost predictions, supported by an information model employed to persist historical information gathered from past projects. To prove the concept and technical feasibility of our solution we consider as a case study the prediction of costs (either development/test/support) associated with projects for the deployment of wireless network infrastructures. During the evaluation is demonstrated the effectiveness and efficiency of the model and discussed its potential and limitations in order to help understanding the trade-offs between development/deployment, test, and support costs. Our solution has been evaluated based on real/synthetics data gathered from the ISBSG dataset, and presents results similar to those found in real-life scenarios. Our solution has provided correct estimates for around 80% of the support costs for the scenarios evaluated.

Composite structures can lower the weight of an airliner significantly. Due to the higher process complexity and the high material cost, however, the low weight often comes with a significant increase in production cost. The application of cost-effective design strategies is one mean to meet this challenge. In this thesis, a simplified form of direct operating cost is suggested as a comparative value that in combination with multidisciplinary optimization enables the evaluation of a design solution in terms of cost and weight. The proposed cost optimization framework takes into account the manufacturing cost, the non-destructive testing cost and the lifetime fuel consumption based on the weight of the aircraft, thus using a simplified version of the direct operating cost as the objective function. The manufacturing cost can be estimated by means of different techniques. For the proposed optimization framework, feature-based parametric cost models prove to be most suitable. Paper A contains a parametric study in which a skin/stringer panel is optimized for a series of cost/weight ratios (weight penalties) and material configurations. The weight penalty (defined as the specific lifetime fuel burn) is dependent on the fuel consumption of the aircraft, the fuel price and the viewpoint of the optimizer. It is concluded that the ideal choice of the design solution is neither low-cost nor low-weight but rather a combination thereof. Paper B proposes the inclusion of non-destructive testing cost in the design process of composite components, and the adjustment of the design strength of each laminate according to inspection parameters. Hence, the scan pitch of the ultrasonic testing is regarded as a variable, representing an index for the guaranteed material quality. It is shown that the cost for non-destructive testing can be lowered if the quality level of the laminate is assigned and adjusted in an early design stage. In Paper C and Paper D the parameters of the manufacturing processes are upgraded during the cost optimization of the component. In Paper C, the framework is extended by the cost-efficient adaptation of parameters in order to reflect the situation when machining an aluminum component. For different weight penalties, the spar thickness and stringer geometry of the provided case study vary. In addition, another cutter is chosen with regard to the modified shape of the stringer. In Paper D, the methodology is extended to the draping of composite fabrics, thus optimizing not only the stacking layup, but also the draping strategy itself. As in the previous cases, the design alters for different settings of the weight penalty. In particular, one can see a distinct change in fiber layup between the minimum weight and the minimum cost solution. Paper E summarizes the work proposed in Papers A-D and provides a case study on a C-spar component. Five material systems are used for this case study and compared in terms of cost and weight. The case study shows the impact of the weight penalty, the material cost and the labor rate on the choice of the material system. For low weight penalties, for example, the aluminum spar is the most cost-effective solution. For high weight penalties, the RTM system is favorable. The paper also discusses shortcomings with the presented methodology and thereby opens up for future method developments. / QC 20100723 / European Framework Program 6, project ALCAS, AIP4-CT-2003-516092 / Nationella flygtekniska forskningsprogrammet (NFFP) 4, project kostnadseffektiv kompositstruktur (KEKS)

For many products, the adaptation to customer specifications is essential and requires flexible product design and manufacture while maintaining competitive pricing. Engineering design is often concerned with striking a good balance between product properties, e.g. performance, and the resources required to manufacture and assemble the product. When different courses of action are to be evaluated, even seemingly small changes in customer requirements, product design, and manufacturing properties have to be handled with caution. Small changes can entail products with: low level of conformability with the manufacturing system, highly increased cost, and extended manufacturing lead-time. For most companies, the manufacturing system is a valuable asset that is more or less fixed and only minor adaptations are allowed. This implies that the product design has to be adapted to the manufacturing system to a large extent. Design for producibility (DFP) is the process in which a systematic method is used to reach the required functional properties of the product at the same time as good compliance with the manufacturing system is ensured. The DFP process usually needs to involve several persons simultaneously for the purpose of sharing information and knowledge. For many manufacturing companies, the collaboration between engineering design and production engineering is a critical issue and they have to improve their methods and tools for ensuring and enhancing producibility. This can be achieved by introducing computer-supported design for producibility. The present research is intended to contribute to the development and utilisation of different application systems that can be used as such computer support. The aim is to provide companies with support in application system development and to show how different application systems can be used in a systematic way as means to ensure and enhance producibility. The competitive advantages to gain from introducing computer-supported design for producibility are: product designs with high level of conformability with the production system, shortened manufacturing lead-time, and decreased manufacturing cost. This work contributes to the achievement of these advantages by introducing a framework with principles and models supporting application systems development. Three types of application systems are presented and their practical usefulness is examined, showing practitioners how producibility aspects can be assessed systematically. The main scientific and theoretical contribution of the work comprises: the descriptions concerning how to structure and describe the product and product-related information (manufacturing requirements, costs, process plans and production resources), the foundation of different information models, and the clarification of the models’ interrelationships. This is perceived as a contribution to a better understanding of the domains and how they relate to each other.Design for producibility (DFP) is the process in which a systematic method is used to reach the required functional properties of the product at the same time as good compliance with the manufacturing system is ensured. The DFP process usually needs to involve several persons simultaneously for the purpose of sharing information and knowledge. For many manufacturing companies, the collaboration between engineering design and production engineering is a critical issue and they have to improve their methods and tools for ensuring and enhancing producibility. This can be achieved by introducing computer-supported design for producibility. The present research is intended to contribute to the development and utilisation of different application systems that can be used as such computer support. The aim is to provide companies with support in application system development and to show how different application systems can be used in a systematic way as means to ensure and enhance producibility.

Contemporary enterprises depend to great extent on software systems. During the past decades the number of systems has been constantly increasing and these systems have become more integrated with one another. This has lead to a growing complexity in managing software systems and their environment. At the same time business environments today need to progress and change rapidly to keep up with evolving markets. As the business processes change, the systems need to be modified in order to continue supporting the processes. The complexity increase and growing demand for rapid change makes the management of enterprise systems a very important issue. In order to achieve effective and efficient management, it is essential to be able to analyze the system modifiability (i.e. estimate the future change cost). This is addressed in the thesis by employing architectural models. The contribution of this thesis is a method for software system modifiability analysis using enterprise architecture models. The contribution includes an enterprise architecture analysis formalism, a modifiability metamodel (i.e. a modeling language), and a method for creating metamodels. The proposed approach allows IT-decision makers to model and analyze change projects. By doing so, high-quality decision support regarding change project costs is received. This thesis is a composite thesis consisting of five papers and an introduction. Paper A evaluatesa number of analysis formalisms and proposes extended influence diagrams to be employed for enterprise architecture analysis. Paper B presents the first version of the modifiability metamodel. InPaper C, a method for creating enterprise architecture metamodels is proposed. This method aims to be general, i.e. can be employed for other IT-related quality analyses such as interoperability, security, and availability. The paper does however use modifiability as a running case. The second version of the modifiability metamodel for change project cost estimation is fully described in Paper D. Finally, Paper E validates the proposed method and metamodel by surveying 110 experts and studying 21 change projects at four large Nordic companies. The validation indicates that the method and metamodel are useful, contain the right set of elements and provide good estimation capabilities. / QC20100716

Over the last few decades the design of high lift devices has become a very important part of the total aircraft design process. Reviews of the design process are performed on a regular basis, with the intent to improve and optimize the design process. This thesis describes a new and innovative methodology for the design and evaluation of mechanisms for Trailing Edge High-Lift devices. The initial research reviewed existing High-Lift device design methodologies and current flap systems used on existing commercial transport aircraft. This revealed the need for a design methodology that could improve the design process of High-Lift devices, moving away from the conventional "trial and error" design approach, and cover a wider range of design attributes. This new methodology includes the use of the innovative design tool called SYNAMEC. This is a state-of-the-art engineering design tool for the synthesis and optimizations of aeronautical mechanisms. The new multidisciplinary design methodology also looks into issues not usually associated with the initial stages of the design process, such as Maintainability, Reliability, Weight and Cost. The availability of the SYNAMEC design tool and its ability to perform Synthesis and Optimization of mechanisms led to it being used as an important module in the development of the new design methodology. The SYNAMEC tool allows designers to assess more mechanisms in a given time than the traditional design methodologies. A validation of the new methodology was performed and showed that creditable results were achieved. A case study was performed on the ATRA - Advance Transport Regional Aircraft, a Cranfield University design project, to apply the design methodology and select from within a group of viable solutions the most suitable type of mechanism for the Variable Camber Wing concept initially defined for the aircraft. The results show that the most appropriate mechanism type for the ATRA Variable Camber Wing is the Link /Track Mechanism. It also demonstrated how a wide range of design attributes can now be considered at a much earlier stage of the design.

Most aircraft component are currently being manufactured by machining, forging, welding and also assembling such parts. However, the possibilities of cutting cost from a single component has brought about a growing trend towards looking into casting as a possible option for manufacturing aircraft parts. This thesis was done at the request of Saab Avitronics. It evaluates the possibilities of one aircraft part, a chassis for an electronic unit that was first designed to be machined from a blank, to be cast. The thesis goes through the multifaceted tasks of product development. Casting process selection, cast alloy selection as well as geometry modification were some of these tasks that were performed in this thesis. It also evaluates the performances of chosen casting processes, the design of gating systems as well as various process parameters set, by simulating the casting processes. The alloy chosen was A356.0 with a T6 temper and the casting processes chosen were plaster mold casting and rheocasting. The geometry of the original chassis, which had very thin sections and undercuts which were complex to cast, was modified and made easier to cast with an acceptable slight increase of mass and size. The modification done on the geometry as well as the gating systems used had proven to be worthwhile, as the simulation of both process showed that such a part can be casted with no crucial defects foreseen. However, probable cavities might occur at the very tip of the chassis’s thin-fins – that it has for carrying away heat. Minor subsurface porosities might also be formed, which would not impair the function of the chassis. The modified chassis was made as close to as finished piece as possible, for the purpose of reducing machining costs. The cost of producing such a part by casting was also seen to be much less than machining it from blank. This could be taken as rationale for casting the chassis with thicker sections, to avoid problems that may arise in casting, and to subsequently machine these faces later, as it would still be cheaper than machining the chassis from a blank.

Availability of historical unit cost data is an important factor in developing accurate project cost estimates. State highway agencies (SHAs) collect data on historical bids and/or production rates, crew sizes and mixes, material costs, and equipment costs, including contractor overhead and profit. The objective of this research is to create a framework to define a standardized and a systematic approach for developing unit costs for construction project estimating. A literature review was conducted that provided an overview of estimating techniques used in project estimating, estimation guidelines maintained by SHAs, and information systems used in the estimation process. After gaining a broad overview of the industry‘s approach to unit cost development, a survey was then conducted. The purpose of the survey was to identify the state of practice in SHAs for unit cost development. The survey helped to identify SHAs doing considerable work in unit cost development and interviews were conducted with these agencies to know their unit cost development process in detail. The results from survey and the interviews were then used in defining the framework. The framework provides a standardized way to use historical data for preparing construction project estimates.

As the construction sector is becoming more competitive in recent years, it has become more important to estimate the duration and cost of the construction projects and to calculate the risks&rsquo / effects correctly. The aim of this thesis is to estimate the duration and cost of construction projects accurately using an activity based risk assessment method which is based on the integrated duration &ndash / cost influence network diagram model proposed by Tah and Poh (2006). Within the context of this thesis, a web based risk assessment tool using the integrated duration &ndash / cost influence network at an activity level is developed to estimate the possible cost overrun and delay in construction projects. Risk breakdown structure for construction projects is created which enables the evaluation of risk effects at an activity level. The developed tool uses Monte Carlo Simulation Technique and Risk Rating Method. The results of the developed tool are compared with those of traditional methods and the reliability of the developed tool is validated.

Energy is increasingly becoming more important in today&rsquo / s world. Ascending of energy consumption due to development of technology and dense population of earth causes greenhouse effect. One of the most valuable energy sources is hydro energy. Because of limited energy sources and excessive energy usage, cost of energy is rising. There are many ways to generate electricity. Among the electricity generation units, hydroelectric power plants are very important, since they are renewable energy sources and they have no fuel cost. Electricity is one of the most expensive input in production. Every hydro energy potential should be considered when making investment on this hydro energy potential. To decide whether a hydroelectric power plant investment is feasible or not, project cost and amount of electricity generation of the investment should be precisely estimated. This study is about cost estimation of hydroelectric power plant projects. Many design parameters and complexity of construction affect the cost of hydroelectric power plant projects. In this thesis fifty four hydroelectric power plant projects are analyzed. The data set is analyzed by using regression analysis and artificial neural network tools. As a result, two cost estimation models have been developed to determine the hydroelectric power plant project cost in early stage of the project.