Dissertations / Theses on the topic 'CAD ENVIRONMENT'

For many companies, design related information mainly exists as rooms of paper-based archives, typically in the form of manufacturing drawings and technical specifications. This 'static' information cannot be easily reused. The work presented in this thesis proposes a methodology to ease this problem. It defines and implements a computer-based design tool that will enable existing design families to be transformed into 'dynamic' CAD-based models for the Conceptual, Embodiment and Detailed stages of the design process. Two novel concepts are proposed here, i) the use of a Function Means Tree to store Conceptual and Embodiment design and ii) a Variant Method to represent Detailed design. In this way a definite link between the more abstract conceptual and the concrete detailed design stages is realised by linking individual detailed designs to means in the Function Means Tree. The use of the Variant Method, incorporating 'state-of-the-art' developments in Solid Modelling, Feature-Based Design and Parametric Design, allows an entire family of designs to be represented by a single Master Model. Therefore, instances of this Master Model need only be stored as a set of design parameters. This enables current design families and new design cases to be more created more efficiently. Industrial Case Studies, including a Lathe Chuck family, a Drive-End casting and a family of Filtration Systems are given to prove the methodology.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 1999.
Includes bibliographical references (p. 67-69).
by Gangadhar Konduri.
S.M.

Flap, aileron, rudder, elevator, speed brake, stick, landing gear and similar movable systems used in aerospace industry have to operate according to the defined requirements and mechanisms used in those systems have to be synthesized in order to fulfill those requirements. Generally, without the use of synthesis tools, synthesis of mechanisms are done in CAD environment by trial-error and geometrical methods due to the complexity of analytical procedures. However, this approach is time consuming since it has to be repeated until the synthesized mechanism has suitable mechanism properties like transmission angle and connection points. Due to above reasons, a software developed for synthesis of mechanisms within the CAD environment can utilize all the graphical interfaces and provides convenience in mechanism design. In this work, it is aimed to develop a four-bar mechanism synthesis tool which is compatible with CATIA V5 by considering the requirements of aerospace industry. This tool performs function, path and motion synthesis and shows suitable mechanisms in CATIA according to input obtained from CATIA and mechanism properties.

Assembly-oriented design offers great potential for product rationalisation, increasing productivity and reducing lead time and cost. It results in simpler and more reliable products which are less expensive to assemble and manufacture. To facilitate assembly-oriented design, an assembly-oriented CAD environment is needed to incorporate Design for Assembly (DFA) evaluation from an early design stage. Assembly planning should also be integrated to support the DFA evaluation. This thesis reports the results of research towards supporting such an assembly-oriented CAD environment. A novel approach has been used to deploy an Expert Assembler to support proactive DFA evaluation and assembly sequence definition. This is particularly useful, as designers are rarely if ever assembly experts. Based on the fact that there are several areas needing expert support in this assembly-oriented CAD environment, but that different areas have very different requirements and different knowledge is involved, the Expert Assembler deployed contains several separated modules. Each module is an expert agent devised to tackle a problem area that uses a suitable problem solving strategy, knowledge representation and reasoning method. This brings a number of advantages that are detailed in the thesis. The thesis presents systematical ideas for support proactive DFA, with the focus on support for part count reduction and assembly sequence generation. This is realised by three elements of the expert agents: Part Count Advisor, Starting Part Advisor, and Next Part Advisor. Part count reduction is usually based on dialogue with the user. There is little computational support for this issue in any of the DFA methodologies and related literature. This research fills the gap: it brings computational support for part count reduction from the early design stage. The work has also made new progress in assembly sequence generation. The Starting Part Advisor and the Next Part Advisor cooperate with each other and with the user to provide suggestions dynamically and transparently regarding base part and the most suitable next part selection in assembly sequence definition. Case studies were used to test the effectiveness of the Advisors.

Undo is a command that users rely on in most software applications. Its importance in multi-user CAD is no different. However, due to its unique nature, users may have different expectations regarding how undo should behave. This research seeks to better understand users' expectations regarding undo in multi-user CAD by having users participate in collaborative design exercises and then asking them how they would expect undo to behave. In addition, users participated in a survey in which they watched 8 videos showing users interacting within multi-user CAD and were then asked about how they would want undo to behave. Based on these findings, various recommendations are made for how undo ought to be implemented in multi-user CAD. These include recommendations regarding the user experience/user interface as well as proposing an equation that seeks to quantify whether a user expects to share an undo stack with another user or if they should only be able to undo their own actions.

In today's competitive global market, there is an ever-increasing demand for highly skilled engineers equipped to perform in teams dispersed over several time-zones by geography. Aerospace Partners for the Advancement of Collaborative Engineering (AerosPACE) is a senior design capstone program co-developed by academia and industry to help students develop the necessary skills to excel in the aerospace industry by challenging them to design, build, and fly an unique unmanned aerial vehicle (UAV). Students with little to no experience designing UAVs are put together in teams with their peers from geographically dispersed universities. This presents a significant challenge for the students in assimilating and applying aircraft design principles, using and interpreting output from analysis tools in multiple disciplines, and communicating their findings with their team members in an effective way. This thesis documents the development of a collaborative design tool for the generation and evaluation of small-scale electric-powered UAV concepts in AerosPACE. The integrated design and optimization software CCADE (Collaborative Conceptual Aircraft Design Environment) enables the immersion of team members from different universities in a software environment which shares design information and analysis results in a central database. Input files for use by open-source analysis tools are automatically generated, and output files read in and displayed in a user-friendly graphical interface. Analysis codes for initial sizing, geometry, airfoil selection, aerodynamics, propulsion, stability and control, and structures are included in the software. Optimization methods are proposed for implementation in future versions of CCADE to explore the breadth of the design space and help students understand the sensitivity of their design to certain key parameters. Testing of CCADE by students during the 2014-2015 AerosPACE course showed an increased volume of explored concepts and prompted questions from students to fill gaps in understanding of fundamental principles. Suggestions for increased student acceptance and use of the software are given. Through its unique architecture and application, CCADE aims to increase productivity and teamwork among AerosPACE participants by increasing the number of concepts which can be fully analyzed, enabling broader exploration of the feasible design space to produce unique and innovative aircraft configurations, and allowing teammates to share thoughts and learning via a shared design and analysis work-space.

Much progress has been made in recent years in the development of Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) tools for engineering design, analysis, and manufacturing. Unfortunately, most of these CAD/CAM applications were constructed independently and without standardization. In essence, they automate a single aspect of design, analysis, or manufacturing and cannot be combined to form a cohesive environment, since integration among applications was not addressed during the design phase of CAD/CAM application software creation. In view of this problem, a novel approach is suggested for software integration of applications in a network environment. The distributed integration solution described in this dissertation employs a new "integration client/server" relationship, where the integration server is the core of the system, providing functions to translate or transform data between applications. The integration client consists of an interface with the server, a CAD/CAM application, and a user interface with the integrated system called the GRIM (GRaphical Interface Manager). There is only one integration server in the system, but there may be an unlimited number of clients. The solution created for distributed integration is implemented in a Computer-Aided Software Engineering (CASE) workbench, geared specifically toward the generation of integration systems. This workbench is known as the CAD/CAM CASE Workbench, and includes an integration solution as well as standard CASE tools. The integration solution contains several tools which will aid a system designer in generating integration systems for CAD/CAM applications. Included is the distributed integration solution described in this dissertation. The distributed integration solution is designed to facilitate the semi-automatic generation of an integration system. It consists of an integration server at the center of the integration system which manages the exchange of data among the integration clients. The integration clients are the CAD/CAM applications in the context of the integration system. To use the distributed integration solution, the integration system designer will customize portions of the structure charts, data dictionary, and module specifications contained in the workbench according to the needs of the applications programs and generate C-source code defining the integration system. Using the distributed integration solution, the user will be able to effect data requests for applications, using the GRIM to interact with the system. All data exchanges are request driven. In addition to the distributed integration solution, this research includes a prototype integrated system which allows data to be requested from one application, and translated to a second for display and manipulation. The prototype was tested in a distributed environment and the results are described.
Ph. D.

A significant problem that users encounter when they must work co-operatively in a CAD engineering environment is the lack of support for data management and data control. In data management the main problems are the mismatch between data models used by users and the CAD engineering environment, the absence of mechanisms for tracking data evolution, and the lack of support for integrating data produced by multiple designers. In data control the main problems are the lack of suitable co-operative development activities, the absence of suitable data-ownership mechanisms, and the lack of control of changes-notification mechanisms. These deficiencies in existing CAD engineering environments motivated the author to provide a solution by designing and prototyping a data server. The data server is an object-oriented datastore which is equipped with a services-layer. This services-layer supports both the data management and data control aspects in a co-operative CAD engineering environment. To implement these two functions and to narrow the data model semantics gap, the object-oriented model has been extended with a construct which captures not only the structural and behavioral parts of data, but also semantic relationships among data. The four services provided by the services-layer are the versioning service which addresses the tracking of data evolution, the configuration management service designed to support co-operative work, the data-ownership service which controls and safeguards the release of data during multi-stream development, and the changes-notification service that enhances the dynamic data control capability of the CAD engineering environment.

This research presents a new method to preserve data consistency in a multi-user CAx environment. The new method includes three types of constraints which work by constraining and controlling both features and users across an entire multi-user CAx platform. The first type of constraint includes locking or reserving features to enable only one user at a time to edit a given feature. The second type of constraint, collaborative feature constraints, allows flexible constraining of each individual feature in a model, and the data that defines it. The third type of constraint, collaborative user constraints, allows the constraining of user permissions and user actions individually or as a group while providing as much flexibility as possible. To further present this method, mock-ups and suggested implementation guidelines are presented. To demonstrate the effectiveness of the method, a proof-of-concept implementation was built using the CATIA Connect multi-user CAD prototype developed at BYU. Using this implementation usage examples are provided to show how this method provides important tools that increase collaborative capabilities to a multi-user CAx system. By using the suggested method design teams will be able to better control how their data is used and edited, maintaining better data consistency and preventing data conflict and data misuse.

SILEX é um ambiente aberto e integrado que busca auxiliar a concepção de CIs. 0 sistema e composto por ferramentas internas (servidoras de recursos) e ferramentas do usuário (clientes de recursos). O usuário interage com o sistema SILEX através de uma interface gráfica baseada em janelas, ativando os recursos de forma padronizada e consistente. Sendo um sistema de CAD, SILEX e formado por um conjunto de módulos (ferramentas) interdependentes. Cada módulo realiza a sua função e transmite seus resultados. O usuário torna-se cliente de um conjunto de processos que concorrentemente responde as suas requisições. A ideia básica esconder do usuário os procedimentos que não estão diretamente ligados ao projeto, como: configuração e forma de interação do usuário com as ferramentas; formato, conversão e local de armazenamento dos dados. A regularidade na utilização é um dos principais objetivo do sistema, tendo em vista as constantes mudanças na forma de integração e utilização das ferramentas. Novos algoritmos, quando disponíveis, são informados aos usuários e estes decidem da inclusão em seus ambientes de trabalho, não necessitando qualquer mudança de código. O projetista de ferramentas e auxiliado no desenvolvimento e integração pois conta com um conjunto de rotinas, normas de codificação e serviços prestados. As rotinas permitem a integração das ferramentas ao ambiente, enquanto que as normas regulam a utilização dos recursos disponíveis. A utilização dos recursos dá-se pelo envio de requisições ao servidor do sistema. Os dados gerados pela interação com as ferramentas estão ligados a um projeto, inicialmente definido e cadastrado. Estes são manipulados por uma ferramenta dedicada, que realiza a leitura, escrita e conversão, liberando as ferramentas do usuário destas tarefas. Centralizados, os dados tem controle de acesso, dependência e versão facilitados. SILEX em sua implementação não se beneficia das facilidades adquiridas com a utilização de um framework comercial, visto que foi totalmente construído sobre uma plataforma Open Windows. O objetivo é inicialmente prover soluções simplificadas e eficazes, que permitam a integração de um conjunto de ferramentas e, subsequentemente, incrementar e expandir a fim de que o SILEX tenha todas as características desejadas e ainda não alcançadas pelos frameworks reportados na bibliografia.
SILEX is an open and integrated system built up to aid the design of integrated circuits. The SILEX System is composed of internal resources and user tools (clients of the resources). The user has at his disposal a graphic interface based on the use of windows, activating tools in an uniform and consistent way. The SILEX CAD system is formed by a set of interdependent modules (tools), each one realizing certain function and transmitting data. The designer is client of a set of processes that answer his/her requests. The main idea of the project is to hide from the final user all tasks which are not directly related to the art of design, like format conversion, data storage and maintenance and user interaction with tools. One of the goals of the system is the regularity in its use, for there is always the need to integrate new tools. The user can suply new algorithms that may be included in the working environment without any change in the SILEX code. The system helps tool designers by suplying them with a set of routines, coding rules and resources. The set of routines allows integration of the tool with the system, while the coding rules normalize the use of the available resources. All data generated by the user interaction with the available tools is linked to a Project, previously defined and cataloged. Data is then handled by a dedicated tool performing I/O, responsible for the reading, writing and converting of data among different tools, freeing User Tools from this task. By being centralized, Project Data are controlled regarding access, dependency and versioning. SILEX is completely built on top of the OpenWindows environment. Its goal is to initially provide simple and efficient solutions that allow the integration of a set of tools. Next tasks will be the enhancement of the system so that SILEX acquires all desirable characteristics not yet reached or reported in the literature.

"This thesis presents an in depth study of Pro/Engineer's manufacturing module and its application into the Computer-Aided Manufacturing (CAM) undergraduate education environment. Mechanical Engineering has a lot to gain by incorporating computers into the undergraduate curriculum in comparison to only the traditional classroom surroundings. Today, complex problems can be solved in mere seconds thanks to the power and speed of current computers. Likewise within today's manufacturing sector, numerical controlled (NC) machines are no longer programmed manually. In today's globally competitive manufacturing environment, integrated systems such as CAD/CAM help reduce the ever-shrinking time to market. This thesis contains the background as well as the curriculum material necessary to teach undergraduate students CAM using Pro/Engineer's manufacturing module. The curriculum material starts with the tutorials to teach and reinforce Pro/Engineer basic sketcher skills, which are necessary background information. Followed with in-depth click tutorials to teach the manufacturing module for 2 axes turning, and 3 axes hole drilling and milling. It also includes the necessary lab manuals that reinforce the class lecture material, an electronic manufacturing exam, and the students' evaluations from 2 terms when the CAM course (ME3820) was offered."

The scope of this study is to illustrate the relationship between computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, and to show how architectural modeling should be positioned in the process of computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The integration of computer aided technologies with architectural design is investigated in terms of design-production/fabrication interaction. The research has been based on a case study in which the CAD/CAM process from the initial design phase to the actual manufacturing of the design object has been explored. A design object is modeled using CAD and the model is manufactured using CAM in order to illustrate the process of CAD/CAM and its potentials related to architectural design and the construction/manufacturing/fabrication process of building. Thus, the study tries to demonstrate what digital tools can provide to the field of architecture, and lists the requirements for architectural modeling to acquire compatibility among the parts of the building process.

An industry survey was conducted to collect information on current collaboration methods and project management and communication structures. The results, along with other design collaboration philosophies, were used to develop a method of coordinating users in a multi-user design space. These thesis methods will regulate collaboration and avoid user collisions in the same model space, either by cooperative interaction or by spatial decomposition with regional blocking. The method partitions the design space by integrating a graphical user interface tool into the engineering application used to define and assign the necessary tasks of the project. A simple implementation of this method proved that it is usable by multiple users, is faster to setup than simple written instructions, and helps to coordinate users to work together efficiently. To enable some of the key capabilities of the method, modern Computer-Aided application (CAx) architecture would need to be revised with multiple users in mind. One constraint example would be to partition the design space geometrically with visible boundaries between user-assigned areas. Current CAx architectures have some selection filtering capability that can be based on mathematical constraint boundaries, but are not designed to globally filter selection and are not very useful in their limited form. A simple solution to working around this limitation has not been found.

CADSYN (Computer Aided Design SYNthesis) is a visual, interactive computer program working under Computer Aided Design (CAD) enviroment, which accomplishes the synthesis and analysis of planar four-bar mechanisms. The synthesis tasks are motion generation, path generation and function generation. During synthesis, the dyadic approach is utilized which introduces vector pairs and complex number algebra to model the motion. The possible solutions can be limited for link dimensions, the center circle point curves within a certain region, transmission angle characteristics, branch and order defects. The designed mechanism can be analyzed for velocity, acceleration and transmission angle and any of the data can be exported to Excel®
for further analysis. The software is designed to provide the user maximum feasible number of solutions. In four multiply separated position synthesis, if there is flexibility in the value(s) of one or any number of input parameter(s), designer can obtain different Burmester curves by changing those parameter(s). Designer can also simulate the kinematics of the mechanism by using drawing functions that are available from the CAD iv enviroment at any time. Drawing parts in the design plane can be attached to any link of the mechanism and can be simulated throughout the motion as part of the link it is attached. As a whole, this computer program is designed to satisfy the needs of mechanism designers while working in CAD enviroment.

Computer Aided Design (CAD) applications have historically been based on a single user per application architecture. Although this architecture is still popular to date, it does have several drawbacks. First of all the single user CAD architecture inhibits a concurrent engineering design process where several designers can work on the same model simultaneously. This limitation introduces time inefficiency especially when a project involves geographically dispersed designers. A solution to these drawbacks could be a transition from the traditional single user CAD architecture to a multiuser collaborative architecture. Advances in computer networking technologies, especially relating to the Internet, have provided the needed tools to make this transition a reality, thus making it possible for designers to simultaneously work on geometric models from one or more networked computers regardless of the location of the user. This new paradigm is expected to improve collaboration and greatly reduce product design times and consequently reduce cost and improve productivity. The multi-user architecture will, however, also require reliable security mechanisms to ensure its successful deployment in an enterprise environment where protection of intellectual property is of critical importance. This thesis proposes a framework to implement authentication, authorization and secure data communications in a multiuser collaborative CAD software system. This framework has been tested on an emerging multiuser collaborative CAD system called v-CAx being developed at Brigham Young University.

Currently in the field of demolition, which generates most of the waste in the construction industry, the treatment of waste largely relies on landfill or degraded recycling, which leads to significant consumption of natural resource and energy and a shortage of landfill site. In order to improve the inefficiency of demolition waste recovery, “to suggest improvements in the environmental impact of the demolition industry in UK” was set as the aim of the present research. After the identification of few opportunities for communication between demolishers and constructers in the current social system, a collaboration support system between these two stakeholders called ‘Demolition Project Mapping’ (DPM) system was suggested. In the system, the impact evaluation tool developed in the 4D-CAD software is applied to the demolition project simulation. This tool allows the users to dynamically simulate the impact of project planning which can be designed in the tool. In the pilot study, the simulation result shows the large potential to reduce the impact (e.g. 28% for the cost) by the tool application.

ASICs estruturados com leiautes regulares representam uma das soluções para a perda de rendimento de fabricação de circuitos integrados em tecnologias nanométricas causada pela distorção de fotolitografia. Um método de projeto de circuitos integrados ainda mais restritivo resulta em ASICs estruturados configuráveis apenas pelas camadas de vias, que são compostos pela repetição do mesmo modelo de bloco em todas as camadas do leiaute, exceto as camadas de vias. A escolha do modelo de bloco tem grande influência nas características do circuito final, criando a demanda por novas ferramentas de CAD que possam avaliar e comparar tais modelos em seus diversos aspectos. Esta tese descreve um ambiente de CAD baseado em SAT, capaz de avaliar o aspecto de capacidade lógica em padrões de blocos configuráveis por vias. O ambiente proposto é genérico, podendo tratar quaisquer padrões de bloco definido pelo usuário, e se comporta de maneira eficiente quando aplicado aos principais padrões já publicados na literatura.
Structured ASICs with regular layouts comprise a design-based solution for IC manufacturing yield loss in nanometer technologies caused by photolithography distortions. Via-configurable structured ASICs is even a more restrictive digital IC design method, based on the repetition of a block template comprising all layout layers except the vias one. The choice of such a design strategy impacts greatly the final circuit characteristics, arising the need for specific CAD tools to allow template evaluation and comparison in different aspects. This work presents a SAT-based CAD environment for evaluating the logical capacity aspect of via-configurable block templates. The proposed environment is able to support any user-defined template, and behaves efficiently when applied to block templates presented in related literature.

The use and application of 4 Dimensional Computer Aided Design (4D CAD) is growing within the construction industry. 4D approaches have been the focus of many research efforts within the last decade and several commercial tools now exist for the creation of construction simulations using 4D approaches. However, there are several key limitations to the current approaches. For example, 4D models are normally developed after the initial planning of a project has taken place using more traditional techniques such as Critical Path Method (CPM). Furthermore, mainstream methodologies for planning are based on individual facets of the construction process developed by discrete contractors or sub-contractors. Any 4D models generated from these data are often used to verify work flows and identify problems that may arise, either in terms of work methods or sequencing issues. Subsequently, it is perceived that current 4D CAD approaches provide a planning review mechanism rather than a platform for a novel integrated approach to construction planning. The work undertaken in this study seeks to address these issues through the application of a distributed virtual reality (VR) environment for collaborative 4D based construction planning. The key advances lie in catering for geographically dispersed planning by discrete construction teams. By leveraging networked 4D-VR based technologies, multidisciplinary planners, in different places, can be connected to collaboratively perform planning and create an integrated and robust construction schedule leading to a complete 4D CAD simulation. Establishing such a complex environment faces both technological and social challenges. Technological challenges arise from the integration of traditional and recent 4D approaches for construction planning with an ad hoc application platform of VR linked through networked computing. Social challenges arise from social dynamics and human behaviours when utilizing VR-based applications for collaborative work. An appropriate 4D-based planning method in a networked VR based environment is the key to gaining a technical advancement and this approach to distributed collaborative planning tends to promote computer-supported collaborative work (CSCW). Subsequently, probing suitable CSCW design and user interface/interaction (UI) design are imperative for solutions to achieve successful applicability. Based on the foregoing, this study developed a novel robust 4D planning approach for networked construction planning. The new method of interactive definition was devised through theoretical analysis of human-computer interaction (HCI) studies, a comparison of existing 4D CAD creation, and 3D model based construction planning. It was created to support not only individual planners’ work but multidisciplinary planners’ collaboration, and lead to interactive and dynamic development of a 4D simulation. From a social perspective, the method clarified and highlighted relevant CSCW design to enhance collaboration. Applying this rationale, the study specified and implemented a distributed groupware solution for collaborative 4D construction planning. Based on a developed system architecture, application mode and dataflow, as well as a real-time data exchange protocol, a prototype system entitled ‘4DX’ was implemented which provides a platform for distributed multidisciplinary planners to perform real-time collaborative 4D construction planning. The implemented toolkit targeted a semi-immersive VR platform for enhanced usability with compatibility of desktop VR. For the purpose of obtaining optimal UI design of this kind of VR solution, the research implemented a new user-centred design (UCD) framework of Taguchi-Compliant User-Centred Design (TC-UCD) by adapting and adopting the Taguchi philosophy and current UCD framework. As a result, a series of UIs of the VR-based solution for multifactor usability evaluation and optimization were developed leading to a VR-based solution with optimal UIs. The final distributed VR solution was validated in a truly geographically dispersed condition. Findings from the verification testing, the validation, and the feedback from construction professionals proved positive in addition to providing constructive suggestions to further reinforce the applicability of the approach in the future.

More and more people commute to work, travel and use the electric bicycle as a daily means of transport. The need for bicycle racks, adapted for electric bicycles is growing and the demands on bicycle racks are higher than for bicycle racks for ordinary bicycles. This as they are very expensive to buy. On behalf of NOLA Industries, a bicycle rack for electric bicycles will be designed. The bicycle rack must also meet the need to recharge the batteries while the bicycle is parked and meet all found requirements from all stakeholders, which were collected during the project. The project is carried out by one student from Luleå University of Technology, who is studying M.Sc. in industrial design with a focus on product development. The project was carried out in Luleå with NOLA at a distance in Stockholm. The aim of the project was to come up with an idea for a bicycle rack that is suitable for public environments and that also fits into NOLA’s existing product range. At the beginning of the project, the time was planned using a Gantt scheme. The process used was CDIO consisting of four different phases. After the planning was completed, a benchmarking was made of how the situation looked and how the electric bicycles in today’s society work. The theory section was planned and introduced with a description of the line of technical design. The chapter was then followed up with relevant theory for the project. In order to find out what users think of existing bicycle racks and what were the desires for future bicycle racks, a survey was sent out. The work continued with several different information collection methods which were then followed up with creative work in the design phase. The final work included CAD models and renderings from keyshot of the finished concept. The final concept meets stakeholder requirements for an electric bike rack. It fulfill the need to be able to recharge the electric bike’s battery and to lock the electric bike in several points. The roof and the bicycle racks are equipped with led lighting, counteracting vandalism and theft of the electric bicycles. The roof also protects the electric bicycles against weather conditions.

In terms of technology, BIM is also part of the worldwide change Industry 4.0, which in essence is the trend toward automation and data exchange in manufacturing technologies and processes. Generative design is an iterative process that involves a program that will generate a certain number of outputs that meet certain constraints, so that a designer is able to fine tune the feasible project by changing minimal and maximal values of an interval in which a variable of the program meets the set of constraints, in order to reduce or augment the number of outputs to choose from. The initial idea of this thesis work was to manipulate few of the most basic geometric elements in order to get a complex parametric shape inspired from the honeycomb as the natures perfectly generated the element. This preliminary idea, together with the ambition to use this transformation for a façade system in a structural building led us to a series of decisions to try and connect two “worlds”, in the sense that we have a CAD environment that lets us create the geometry and a BIM environment where everything is represented by a specific level of information. This geometry is given a specific set of rules that drive and manipulate each of the elements it contains in a certain fashion. This methodology, as well as the communication and the interaction between the software adopted and their programming environments, is what makes the generative design possible. This result from the Grasshopper algorithm is then being created in the CAD environment in Rhinoceros3D, which then can be opened through Rhino.Inside.Revit and give us a direct real-time preview in the BIM environment in Revit. Through a long series of testing and experimenting with the geometry, we get to a point where we have a functional algorithm that creates and manipulates the geometry, in order to foster many design opportunities for structural and architectural designers.

The oases of the northern Sahara illustrate the possibility that people and nature can work together to enhance life in a harsh and variable environment. This research investigates fifty years of experiences of living with environmental change in oasis systems, bringing together new data, archived environmental records and cultivators` observations. These are combined to gain insight into the environmental change processes, and the experiences gained by people through living with them in this regional context. Two detailed case studies deepen understanding of the socioeconomic dimensions and significance of these changes over the past two decades. The findings show how environmental changes constrained smallholders` traditional ecosystem management practices. Collective associations were weakened or disintegrated. National systems for environmental management and monitoring were overwhelmed. International recommendations for economic approaches to resource management and innovation to address water scarcity did not prove effective. On the other hand, instances where the international market transition appeared to be creating new opportunities for the restoration of common pool resource management were also identified. This investigation enabled a new perspective on the global dryland management debate to be generated in a context where research has most commonly been concentrated on national sectoral objectives for productivity and desert reclamation. Theoretical insights regarding the application of interdisciplinary research to understand environmental change, further research needs, and potential solutions are directly transferable to other regions where desiccation, salinization and groundwater degradation are accelerating due to climatic and global market-driven changes in land and water use.

This research investigates computer-based collaborative design environments, in particular issues of real-time collaborative 3D CAD. The thesis first presents a broad perspective of collaborative design environments with a preliminary case study of team design activities in a conventional and a computer mediated setting. This study identifies the impact and the feasibility of computer support for collaborative design and suggests four kinds of essential technologies for a successful collaborative design environment: information-sharing systems, synchronous and asynchronous co- working tools, project management systems, and communication systems. A new conceptual framework for a real-time collaborative 3D design tool, Shared Stage, is proposed based upon the preliminary study. The Shared Stage is defined as a shared 3D design workspace aiming to smoothly incorporate shared 3D workspaces into existing individual 3D workspaces. The addition of a Shared Stage allows collaborating designers to interact in real-time and to have a dynamic and interactive exchange of intermediate 3D design data. The acceptability of collaborative features is maximised by maintaining consistency of the user interface between 3D CAD systems. The framework is subsequently implemented as a software prototype using a new software development environment, customised by integrating related real-time and 3D graphic software development tools. Two main components of the Shared Stage module in the prototype, the Synchronised Stage View (SSV) and the Data Structure Diagram (DSD), provide essential collaborative features for real-time collaborative 3D CAD. These features include synchronised shared 3D representation, dynamic data exchange and awareness support in 3D workspaces. The software prototype is subsequently evaluated to examine the usefulness and usability. A range of quantitative and qualitative methods is used to evaluate the impact of the Shared Stage. The results, including the analysis of collaborative interactions and user perception, illustrate that the Shared Stage is a feasible and valuable addition for real-time collaborative 3D CAD. This research identifies the issues to be addressed for collaborative design environments and also provides a new framework and development strategy of a novel real-time collaborative 3D CAD system. The framework is successfully demonstrated through prototype implementation and an analytical usability evaluation.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.
Leaf 46 blank.
Includes bibliographical references (leaves 44-45).
Over the last decade improvements in design technology has taken grand steps in changing the way we build the structures of tomorrow. Conventional drafting software like AutoCAD and Microstation are being challenged by tools that go beyond the two dimensional representational abilities of paper documentation and replacing it with complex three dimensional virtual construction files that are more comprehensible and offer more flexibility with respect to design and also in terms of inter-professional communication. My interest's lie in the new dialectic emerging between architects and fabricators, who ironically sit at opposite ends of the construction spectrum yet are now collaborating with the help of modern-day software. I envision these new tools as being pivotal in both reassigning the roles of design and creating a more seamless construction process. It is this modified construction process that I intend to explore through this thesis.
by Christopher Peter Wodzicki.
M.Eng.

Taxis are a necessary mean of transport in cities for meeting the mobility needs of its citizens. The impact of the taxi market in the daily life is quite important, concerning both financial (e.g. taxi drivers' salaries) and societal issues (e.g congestion, travel demand satisfaction). Therefore, it is crucial to develop models and tools in an effort to help decision makers control the taxi market and meet the customers' requirements for an adequate level of service. In this direction, various methodologies have been developed aiming at quantifying the impacts and evaluating the performance of the taxi sector, initially from an aggregated and economic equilibrium perspective and recently from an operational and more realistic one. The main objective of this thesis is to develop models that analyze the provision of taxi services, emphasizing on the optimal number of taxis that are in order to provide a reasonable waiting time for customers and assure a minimum profitability to the taxi drivers. For this purpose, two models are developed, an analytical economic one and an agent-based simulation one. The first model is able to analyze the taxi market in a macroscopic way, using average values for the taxi drivers' cost and performance in the area of study for obtaining the optimum number of taxis for achieving the minimum unitary system cost and the related waiting time to this optimum fleet. The second model is able to analyze the operational characteristics of the taxi sector in detail, simulating taxi trips in a road network and recording all the performance indicators related to the operational efficiency of the sector. Observed data from the city of Barcelona are used for calibrating the developed models and obtaining the results of their application to the city of Barcelona. The developed models perfectly complement each other. Their combination can prove to be a valuable tool for decision makers when analyzing the performance of the taxi sector or when meeting policy related decisions. At the same time, local operation issues can be analyzed in detail when designing taxi policy related issues since all actors are included within the models and can be taken into account when optimizing this performance. The models are used for analyzing the impact of pricing policies in the taxi market, evaluating the demand for taxi trips related to various fare levels and fleet sizes. Policy issues related to the taxi shifts are also taken into account through the development of an optimization problem for matching the optimum supply levels to the ones provided by a shift-based taxi policy, which is the most common around the world. Optimum ranges of demand are obtained for the hailing, the dispatching and the stand operation modes. Dispatching mode appears to be more efficient at low demand levels, while the hailing mode present lower unitary costs for high demand levels. Aggregated models tend to underestimate the costs of both the customers and the system between 15% and 30% if the demand distribution is uniform. For non-uniform demands, the aggregated models overestimate costs between 20% and 300%, depending on the GINI value of the demand distribution.
Els taxis són un mode de transport necessari per satisfer les necessitats de la població relacionades amb la mobilitat. L'impacte del mercat del taxi a la vida quotidiana és molt important, tant des del punt de vista econòmic (per exemple, els salaris dels taxistes) com social (per exemple, la congestió o la satisfacció de la demanda de desplaçaments). S’han desenvolupat diversos models amb l'objectiu de quantificar els impactes i avaluar el rendiment del sector del taxi, inicialment des d'un punt de vista agregat i econòmic i, recentment, des d'un punt de vista operacional i més realista. L'objectiu principal d'aquesta tesi és el de desenvolupar models d’estudi dels serveis oferts pel sector del taxi, fent èmfasi en el dimensionament de la flota òptima de taxis necessària per satisfer la demanda oferint un temps d’espera raonable per als clients i assegurant al mateix temps una mínima rendibilitat als taxistes. Per a aquest propòsit, s'han desenvolupat dos models, un econòmic analític i un de simulació basada en agents. El primer model és capaç d'analitzar el mercat dels taxis des d'un punt de vista macroscòpic mitjançant l’ús de valors mitjans representatius de tota la regió per obtenir el nombre òptim de taxis que satisfarà les necessitats de la població amb uns costos unitaris mínims, obtenint també el temps d'espera relacionat a aquesta flota òptima. El segon model és capaç de reproduir les característiques operacionals del sector del taxi en detall, simulant viatges en taxi a la xarxa viaria i enregistrant tots els indicadors de rendiment relacionats amb l’eficiència operacional del sector del taxi. S'utilitzen dades reals de la ciutat de Barcelona per al calibratge dels models proposats i per a l'obtenció dels resultats de l'aplicació d’ambdós models al sector del taxi de la ciutat de Barcelona. Els dos models desenvolupats es complementen perfectament, la seva combinació pot ser una eina valuosa per als responsables de la regulació del sector del taxi, ja que els permetrà analitzar els serveis del taxi i prendre les decisions correctes per millorar els servies oferts. Al mateix temps, els problemes operacionals poden ser analitzats en detall durant la fase de disseny de la política de taxis, ja que tots els actors estàn inclosos dins dels models i es tenen en compte alhora d'optimitzar el rendiment del sector del taxi. Els models s'utilitzen per analitzar l'impacte de les polítiques tarifaries en el mercat del taxi. També es te en compte la política de torns, per la qual s’ha plantejat un problema d'optimització que fa coincidir el nombre òptim de vehicles obtingut dels models amb el real proporcionat per la política de torns, que és la més comú a tot el món . Es presenten rangs òptims de demanda per als tres modes operatius. Els sistemes de taxi basats en centraletes telefòniques es mostren més eficients per baixes concentracions de demanda, mentre que els sistemes de taxi al carrer presenten menors costos unitaris per altes concentracions de demanda. Els models agregats tendeixen a subestimar els costos, tant dels clients com del sistema entre el 15% i el 30% si la distribució de la demanda és uniforme. Per demandes no uniformes, els models agregats sobreestimen els costos entre un 20% i 300%, depenent del valor de GINI de la distribució de la demanda.
Los taxis son un modo de transporte necesario para satisfacer las necesidades de la población relacionadas con la movilidad. El impacto del mercado de taxis en la vida cotidiana es muy importante, tanto desde el punto de vista económico (por ejemplo, los salarios de los taxistas) como social (por ejemplo, la congestión o la satisfacción de la demanda de viajes). Varios modelos han sido desarrollados con el objetivo de cuantificar los impactos y evaluar el rendimiento del sector del taxi, inicialmente desde un punto de vista agregado y económico y, recientemente, desde un punto de vista operacional y más realista. El objetivo principal de esta tesis es el de desarrollar modelos que se ocupen de los servicios del sector del taxi, dando énfasis en el número óptimo de taxis necesarios para satisfacer la demanda ofreciendo un tiempo de espera razonable a los clientes y asegurando una mínima rentabilidad a los taxistas. Para este propósito se han desarrollado dos modelos, uno económico analítico y uno basado en simulación de agentes. El primer modelo es capaz de analizar el mercado del taxi desde un punto de vista macroscópico mediante el uso de valores medios para toda la región y de obtener el número óptimo de taxis que satisfará las necesidades de transporte a un coste unitario mínimo, obteniendo también el tiempo de espera relacionado a esta flota óptima. El segundo modelo es capaz de reproducir las características operacionales del sector del taxi en detalle, simulando viajes de taxi en una red viaria y registrando todos los indicadores de rendimiento relacionados con el funcionamiento eficiente del sector del taxi. Se utilizan datos reales de la ciudad de Barcelona para la calibración de los modelos propuestos y la obtención de los resultados de la aplicación de ambos modelos al sector del taxi de la misma ciudad. Los dos modelos desarrollados se complementan perfectamente. Su combinación puede ser una herramienta valiosa en el análisis de los servicios de taxi o cuando se toman decisiones políticas en un esfuerzo para mejorarlos. Al mismo tiempo, problemas de funcionamiento locales pueden ser analizados en detalle durante el diseño de las cuestiones relacionadas con la política de taxis ya que todos los agentes se incluyen en los modelos y se pueden tomar en cuenta a la hora de optimizar el rendimiento del sistema. Los modelos se utilizan para analizar el impacto de las políticas tarifárias en el mercado del taxi. Tambien se tiene en cuenta la política de turnos, para la qual se ha planteado un problema de optimización que hace coincidir el numero óptimo de taxis obtenido por los modelos con los proporcionados por una política de turnos, que es la más común en todo el mundo. Se presentan rangos óptimos de demanda para los tres modos de operación. El sistema de taxis basado en reservas telefónicas parece ser más eficiente en bajas concentraciones de demanda, mientras que el sistema de taxis en la calle presenta menores costes unitarios para altas concentraciones de demanda. Los modelos agregados tienden a subestimar los costes tanto de los clientes como del sistema entre el 15 % y el 30 % si la distribución de la demanda es uniforme. Para demandas no uniformes, los modelos agregados sobreestiman los costes entre un 20% y 300%, dependiendo del valor de GINI de la distribución de la demanda.
Τα ταξί αποτελούν ένα απαραίτητο μέσο μεταφοράς για την ικανοποίηση των αναγκών μετακίνησης των πολιτών. Οι επιπτώσεις της αγοράς ταξί στην καθημερινή ζωή είναι επομένως πολύ σημαντικές, τόσο σε ότι αφορά οικονομικά (π.χ. οι μισθοί των οδηγών ταξί) όσο σε κοινωνικά θέματα (π.χ. συμφόρηση ή ικανοποίηση της ζήτησης για μετακίνηση). Έτσι, είναι σημαντικό να αναπτυχθούν μοντέλα και εργαλεία σε μια προσπάθεια να ελεχθεί η αγορά των ταξί από τους αντίστοιχους φορείς και να ικανοποιηθούν οι ανάγκες των χρηστών. Διάφορα μοντέλα έχουν αναπτυχθεί με στόχο την ποσοτικοποίηση των επιπτώσεων και την αξιολόγηση των επιδόσεων του κλάδου των ταξί, αρχικά από μια πιο συγκεντρωτική και οικονομική άποψη και, πιο πρόσφατα, από μια λειτουργική και πιο ρεαλιστική άποψη. Ο κύριος στόχος αυτής της διδακτορικής διατριβής είναι η ανάπτυξη μοντέλων που ασχολούνται με την ανάλυση των υπηρεσιών ταξί, με έμφαση στον βέλτιστο αριθμό των ταξί που απαιτούνται για την ικανοποίηση της ζήτησης παρέχοντας ένα εύλογο χρόνο αναμονής και εξασφαλίζοντας έναν ελάχιστο κέρδος στους οδηγούς ταξί. Για το σκοπό αυτό, δύο μοντέλα έχουν αναπτυχθεί, ένα συγκεντρωτικό οικονομικό μοντέλο και ένα μοντέλο προσομοίωσης. Το πρώτο μοντέλο μπορεί να αναλύσει την αγορά ταξί από μια μακροσκοπική άποψη χρησιμοποιώντας μέσες τιμές για το σύνολο της περιοχής για τον καθορισμό του βέλτιστου αριθμού ταξί που θα παρέχει υπηρεσίες ταξί με το ελάχιστο μοναδιαίο κόστος, παρέχοντας επίσης το αντίστοιχο χρόνο αναμονής για αυτό το βέλτιστο στόλο. Το δεύτερο μοντέλο μπορεί να αναλύσει τα λειτουργικά χαρακτηριστικά του κλάδου των ταξί με κάθε λεπτομέρεια, προσομοιώνοντας μετακινήσεις με ταξί σε ένα οδικό δίκτυο και καταγράφοντας όλους τους δείκτες απόδοσης της λειτουργίας του κλάδου των ταξί. Χρησιμοποιούνται πραγματικά δεδομένα από την πόλη της Βαρκελώνης για τη βαθμονόμηση των προτεινόμενων μοντέλων και τον καθορισμό των αποτελεσμάτων της εφαρμογής των δύο μοντέλων στην πόλη της Βαρκελώνης. Τα δύο μοντέλα που αναπτύχθηκαν είναι συμπληρωματικά και ο συνδυασμός τους μπορεί να αποδειχθεί ένα πολύτιμο εργαλείο για τους φορείς λήψης αποφάσεων κατά την ανάλυση της απόδοσης των υπηρεσιών ταξί ή για την λήψη αποφάσεων για τη βελτίωσή τους. Τα τοπικά ζητήματα λειτουργίας μπορούν να αναλυθούν λεπτομερειακά κατά το σχεδιασμό της πολιτικής της αγοράς ταξί. Τα μοντέλα χρησιμποιούνται για την ανάλυση των επιπτώσεων τιμολογησης της αγορας ταξί, αξιολογώντας τη ζήτηση για ταξί που συσχετιζεται σε διάφορα επιπέδα τιμολόγησης με τον αριθμό οχημάτων. Περιλαμβάνονται επίσης θέματα διαχείσης της αγοράς ταξί, όπως η χρήση βαρδιών, που είναι το πιο συνηθισμένο, για την παροχή οχηματοορών υπηρεσίας σε επίπεδα αντίστοιχα της βέλτιστης λύσης. Έχουνε διατυπωθεί βέλτιστα διαστήματα ζήτησης για τις τρεις αγορές ταξί, παρά την οδό, με τηλεφωνική κράτηση και σε στάση. Η αγορά με τηλεφωνική κράτηση φαίνεται να είναι η πιο αποδοτική για χαμηλά επίπεδα ζήτησης, καθώς και η παρά την οδό να είναι η πιο αποδοτική για ψηλά επίπεδα ζήτησης. Τα συγκεντρωτικά μοντέλα υπο-εκτιμούν τα κόστη των χρηστών και του συστημάτος μεταξύ 15% και 30% εαν η κατανομή της ζήτησης είναι ομοιομόρφη. Για μη ομοιομόρφες κατανομές ζήτησης, τα συγκεντρωτικά μοντέλα υπερ-εκτιμούν το κόστος μεταξύ 20% και 300%, βάσει της τιμής του συντελεστή GINI της κατανομής της ζήτησης.

Made available in DSpace on 2016-04-18T12:12:29Z (GMT). No. of bitstreams: 4 Monica Mendonca Maria1.pdf: 763444 bytes, checksum: d5fe5f8d60e9e7bd08aecfc0a88b8198 (MD5) Monica Mendonca Maria2.pdf: 1212194 bytes, checksum: b5f0b63d350777866e3955220d604827 (MD5) Monica Mendonca Maria3.pdf: 1656626 bytes, checksum: c2a9d642d2e4d86b7409ce54aabebe89 (MD5) Monica Mendonca Maria4.pdf: 2215429 bytes, checksum: 64893a7cd54a8d0497c2dc13776f74e4 (MD5) Previous issue date: 2009-02-04
This dissertation presents the technology within BIM and its implication in the architectural and engineering design process. Since the 60 s, aerospace and automotive industries have already revolutionized the way of project with the CAD, and manufacture with the assembly lines. In AEC, the CAD became BIM, a new way of project, build and manage, from conception till life cycle building. This brought a project and construction time reduction, cost and environmental impacts decrease foreseen in LEED and merged in BIM.
Este trabalho objetiva apresentar a tecnologia contida no BIM e suas implicações no processo de projeto da arquitetura e engenharia civil. A partir de 1960, as indústrias, aeronáutica e automotiva, já haviam revolucionado a forma de projetar com o CAD, e de fabricar com as linhas de montagem. Na Arquitetura, Engenharia e Construção, o CAD está evoluindo para o BIM (Building Information Modeling), uma forma de projetar, construir e gerenciar, da concepção ao habite-se, aplicável a todo o ciclo de vida da edificação. Dessa forma houve não só uma redução no tempo de projeto e construção, mas também em custos e impactos ambientais previstos em normas internacionais incorporadas ao BIM.

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Background. Earlier research evaluated the 3D internal fit of CAD/CAM crowns after direct versus indirect laser scanning. To date, no study has evaluated the marginal integrity of all-ceramic crowns milled with different type of scanning systems via different methods of scanning. The purpose of This study was conducted to assess the marginal integrity of all-ceramic crowns milled with the E4D CAD/CAM system (D4D, Richardson, Texas) using three different scanning methods of a prepared model (direct scanning and indirect scanning of a cast, and scanning of an impression material). Methods. A metal die model of a prepared mandibular first molar was fabricated according to specifications for tooth preparation for the E4D CAD/CAM system. Fifty five all-ceramic crowns were milled using this system: 5 crowns were made from scanning of the metal die; 25 crowns were made from scanning of 5 PVS impressions of the metal die, with each impression scanned 5 times; and 25 crowns were made from scanning stone dies poured from the same previous 5 PVS impressions. Each stone die was scanned 5 times. An internal gap to provide space for cement was kept constant at 25 microns. Marginal integrity of the crowns was assessed using optical microscopy. Results. The overall mean marginal gap and standard deviation for crowns was 78.1&mgr;m (18.9) for scanning the metal dies, 148.9&mgr;m (25.4) for scanning impressions and 126.2&mgr;m (28.2) for scanning the stone casts. ANOVA revealed significant differences in marginal gap between the three different groups. Conclusions. The direct scanning of a metal die produced crowns with significantly smaller marginal gaps than the marginal gap seen from scanning a PVS impression or a stone cast (P<.05). Additionally, it was found that scanning PVS impressions or stone casts, produced crowns with unacceptable mean marginal gaps (over 120&mgr;m). It was also observed that difficulty of scanning PVS impressions and tracing the finish line lead to overhanging margins and larger marginal gaps for both crowns produced via that method.

Objective. This study aims to compare several mechanical and optical properties between three different CAD/CAM materials. The properties tested are: flexural strength, modulus of elasticity, hardness, translucency and surface gloss. Background. Typically, CAD/CAM restorations are either ceramic based or resin based. A new resin-ceramic hybrid material has recently been introduced and is thought to combine the advantages of both materials. Methods. Samples were divided into three groups, leucite-reinforced porcelain (IPS Empress CAD), lithium dicilicate (IPS e.max CAD) and resin-ceramic hybrid material (Vita Enamic). Twenty-six bar-shaped specimens were fabricated for each group by cutting standard CAD/CAM blocks. 3-point bending test and Vickers diamond pyramid indenters were used to test the flexural strength and microhardness respectively. Seven veneers were fabricated for each material with a thickness of 0.5 mm using a CAD/CAM milling machine. These veneers were used to test the optical properties via spectrophotometry and gloss-meter analysis. One-way ANOVA, and the Tukey HSD post hoc test were used for statistical analysis between the groups (P

Developments in cutting tools, coolants, drives, controls, tool changers, pallet changers and the philosophy of machine tool design have made ground breaking changes in machine tools and machining processes. Modern Machining Centres have been developed to perform several operations on several faces of a workpiece in a single setup. On the other hand industry requires high value added components, which have many quality critical features to be manufactured in an outsourcing environment as opposed to the traditional in-house manufacture. The success of this manufacture critically depends on matching the advanced features of the machine tools to the complexity of the component. This project has developed a methodology to represent the features of a machine tool in the form of an alphanumeric string and the features of the component in another string. The strings are then matched to choose the most suitable and economical Machine Tool for the component’s manufacture. Literature identified that block structure is the way to answer the question ‘how to systematically describe the layout of such a machining centre’. Incomplete attempts to describe a block structure as alphanumeric strings were also presented in the literature. Survey on sales literature from several machine tool suppliers was investigated to systematically identify the features need by the user for the choice of a machine tool. Combining these, a new alphanumeric string was developed to represent machine tools. Using these strings as one of the ‘key’s for sorting a database of machine tools was developed. A supporting database of machine tools was also developed. Survey on machining on the other hand identified, that machining features can be used as a basis for planning the machining of a component. It analysed various features and feature sets proposed and provided and their recognition in CAD models. Though a vast number of features were described only two sets were complete sets. The project was started with one of them, (the other was carrying too many unwanted details for the task of this project) machining features supported by ‘Expert Machinist’ software. But when it became unavailable a ‘Feature set’ along those lines were defined and used in the generation of an alphanumeric string to represent the work. Comparing the two strings led the choice of suitable machines from the database. The methodology is implemented as a bolt on software incorporated within Pro/Engineer software where one can model any given component using cut features (mimicking machining operation) and produce a list of machine tools having features for the machining of that component. This will enable outsourcing companies to identify those Precision Engineers who have the machine tools with the matching apabilities. Supporting software and databases were developed using Access Database, Visual Basic and C with Pro/TOOLKIT functions. The resulting software suite was tested on several case studies and found to be effective.

Introduction: Dentistry has changed significantly during the last two decades. Patients are more aware and demanding of the latest technologies available in restorative dentistry. The purpose of this study was to determine any possible changes on the surface roughness, gloss and color change of CAD-CAM milled porcelain veneers following repeated milling times, before and after a glazing process. Methods: A Teflon disk-shaped mold was used as a cast to take a digital impression (BlueCam) in order to fabricate cylindrical-shaped specimens. A total of one hundred (N=100) specimens porcelain veneers using Empress CAD (I10) block, were milled using the CAD/CAM CEREC-SIRONA system. The specimens representing the 1 st , 5th , 10th , 15th , 18th and 20th milling times were evaluated to determine any statistical differences regards surface roughness, gloss and color-change. Subsequently, all milled specimens representing the 1 st , 5th , 10th , 15th , 18th and 20th received a standard surface glaze and surface properties (roughness, gloss and color) were re-measured. Results: There was a statistically significant difference in roughness (Pre-glazing) between test groups at different milling times with a determined p value of 0.027. Regard roughness (Pre and Post-glazing) a statistically significant difference was found between test groups on different milling times, which present a p value of 0.18. A statistically significant difference was found in gloss (Pre and Post glazing) between test groups on different milling times. A significantly higher score after glossing, which present a p = 0.791.There was a significant difference found between samples with the same milling time, (Pre and Post the glazing process). The ΔE range between (2.5021 to 3.0418), which is considered to be detectable only by a skilled person and is clinically acceptable. Also, after perform the SEM evaluation of the burs used after 20 milling times, it showed some lost particles leaving some void on the bur surface. Conclusions: There was a statistically significant change in the surface roughness on porcelain veneers processed by CAD/CAM using the same set of burs prior to the glazing process. There was no statistical difference in porcelain surface roughness between samples of the groups Pre-Glazing. Porcelain gloss was altered significantly between groups Pre and Post-Glazing at all milling times. Porcelain Color-shade, value, and hue were significantly altered after the glazing process. There seem to be a considerable change in the physical and optical characteristics (surface roughness, gloss and color-change) after the glazing process, and this likely has a meaningful impact on the clinical aesthetic qualities of the final restoration.

Vid exploatering av mark måste ofta stora volymer jordmassor schaktas bort för grundläggning av hus och anläggning av ledningar och vägar. Dessa jordmassor skickas många gånger till en deponi, vilket orsakar emissioner av miljö- och hälsofarliga gaser från transporter, förbrukning av naturmaterial och innebär även en ekonomisk kostnad.

I Johannelund i västra Stockholm har Stockholms stad planerat ett nytt bostadsområde, och stora mängder jordmassor kommer att behöva schaktas bort under exploateringen. Stockholms stad lät skapa en miljögeoteknisk 3D-modell för att få en översikt över markkvaliteten och bestämma vilka massor som kunde återanvändas för utfyllnad inom området. Med en miljögeoteknisk 3D-modell menas här en CAD-modell i 3D baserad på provtagningar, geotekniska undersökningar och planerad bebyggelse i området. Då detta examensarbete påbörjades var planeringen av Johannelundsprojektet klar och 3D-modellen skapad, men själva bygget hade ännu inte påbörjats.

Syftet med detta examensarbete var att avgöra om miljögeotekniska 3D-modeller bör användas i framtida exploateringsprojekt, och målet var att utvärdera och ge råd om framtida användning av modellen samt att undersöka möjligheterna med att återanvända schaktmassor. En fallstudie gjordes av Johannelundsprojektet där de miljömässiga och ekonomiska konsekvenserna av masshanteringen utvärderades och åsikter om problematiken undersöktes genom intervjuer med myndigheter och intressenter. Vidare bestämdes det underlag som behövs till modellen och en lämplig arbetsordning togs fram. Denna information baserades på beräkningar, eget arbete i 3D-modellen samt intervjuer med involverade i Johannelundsprojektet.

Utvärderingen av Johannelundsprojektet visade att återanvändningen av schaktmassor reducerade kostnader för masshantering med 67 % och emissioner från transporter med 85 % jämfört med om den totala volymen schaktmassor skulle ha skickats på deponi. Vidare visade intervjuerna att myndigheter och intressenter har vitt skilda åsikter vad gäller riktvärden, hantering av schaktmassor och miljögeotekniska 3D-modeller. Studien visade även att om arbetet med 3D-modellen ska bli lyckat krävs bland annat ett fullgott dataunderlag och investering i viss kunskapsutveckling hos personalen.

3D-modeller används allt mer inom samhällsbyggnad, och stora ekonomiska och miljömässiga vinster kan göras genom verktygets möjlighet till effektiv planering och kommunikation. Användning av en miljögeoteknisk 3D-modell rekommenderas i framtida byggprojekt där det förekommer ställvis förhöjda halter av markföroreningar och en omfattande volym schaktmassor beräknas uppkomma.

Land development can cause a great deal of excessive soil masses due to shafting. The total volume of excessive soil is many times transported to a landfill, causing gas emissions, use of natural resources and a significant economical cost.

In a land development project in the area of Johannelund in Stockholm much of the soil masses were planned to be reused instead. To overview the soil quality and decide on what soil masses to reuse and where an Environmental 3D Model for Land Development was used by the City of Stockholm. This means a 3D Model based on soil samples, geotechnical investigations and planned shafting. When the work with this thesis begun the Project Johannelund was already planned and the 3D Model had been created, but the land development had yet not been started.

The aim of this thesis was to decide if Environmental 3D Models should be used in future land development projects, and the goals were to evaluate the model, give advice on future use and to investigate the possibilities to reuse soil masses. A case study of the environmental and economical effects of reusing soil masses in the Project Johannelund was done. Public authorities and stakeholders were interviewed and advices on how to use Environmental 3D Models were given, this includes the data needed to create a model as well as a suggested way of work. The information is based on calculations, personal experience with the 3D Model and interviews with people involved in the Project Johannelund.

The evaluation of the Project Johannelund showed that the reuse of soil masses reduced the costs of transports and land fill fees with 67 %, and the gas emissions from transports with 85 %. The opinions of public authorities and stakeholders vary greatly. Advices on how to use the Environmental 3D Model includes a thorough database and that the staff will need support in order to use the 3D Model properly.

3D Models are used to a larger and larger extent in Urban Management. There are economical and environmental benefits with using the Environmental 3D Model for a more efficient project planning and communication. The City of Stockholm is recommended to use the 3D Model in future land development projects with heterogeneous soil contamination and a large volume of expected excessive soil masses.

A thesis submitted to the College of Dental Medicine of Nova Southeastern University of the degree of Master of Science in Dentistry. Purpose: This study will evaluate the influence of different convergence angles and tooth preparation heights on the marginal adaptation and retention of allceramic CAD/CAM crowns. Materials & Methods: Seventy two typodont teeth (Ivorine teeth; Columbia Dentoform Corp, Long Island City, NY) were prepared using milling burs (Brasseler, USA) and a parallometer (PFG 100, Cendres and Metaux, Switzerland) with 1.0 mm rounded shoulder finish lines. Specimens were divided into 3 groups (n=24) according to 3, 4.5 and 6mm occluso-gingival (O-G) heights. The teeth within each group were then subdivided into 3 subgroups (8 in each sub-group) according to total occlusal convergence (TOC) of 8,16 and 22 degrees. Using the intra-oral camera wand of the Cerec AC machine (Sirona, Germany), optical impressions were made of each tooth. This data was then transferred to the Cerec MC XL milling unit for fabrication of all-ceramic crowns using IPS Empress II (Ivoclar Vivadent, US). The crowns were cemented on typodont teeth with glass ionomer cement. The marginal discrepancy was measured at 6 points with optical microscopy. Retention was evaluated by measuring the tensile force required to dislodge or break the crown from the corresponding tooth preparation in a universal testing machine. Data were analysed using Shapiro-Wilke tests for normality and Leven's tests for equal variances. To look for differences between groups, analysis of variance (ANOVA) with Tukey's HSD test was performed. Results: Mean marginal gap was 35.9 ± 18.4ìm to 81.4 ± 61.3ìm. 2- way ANOVA shows no significant difference in marginal gap among the groups (P< 0.05). The height mean retentive force 183.84 ± 27.0 N, was measured for 6mm height and 8° group and lowest force 86.01±10.75 N, was measured for 3 mm and 22° group. 2- way ANOVA with turkey's HSD test shows significant difference among the groups (P > 0.05). Conclusion: Marginal adaptation of the CAD/CAM all-ceramic crowns is comparable to conventional cast crowns. The preparation recommendation for conventional porcelain fused to metal crowns can be applied to CAD/CAM crown restorations. Retention of cemented CAD/CAM crowns is comparable to conventional cast crowns

A human factors experiment was conducted to investigate the potential benefits of using directional auditory cues in intelligent transportation system technologies in commercial vehicles. Twelve licensed commercial vehicle operators drove a commercial truck-driving simulator and were prompted to select highway numbers on a side-task display. Prompts were presented visually or aurally. Auditory prompts were presented either diotically (both ears simultaneously) or directionally (to either the left or right ear). The search task varied in map density and timing of the prompts in relation to speed limit changes. All experimental conditions were compared to a control condition containing no secondary task. Both driving performance (lane deviation, steering wheel angle, road heading angle error, accidents, and adherence to the speed limit) and secondary task performance (accuracy and response time) measures were collected. Results showed that drivers were able to respond more quickly and accurately to the search task when directional auditory cues were used. Results also showed that driving performance degrades when display density increases and that the use of directional auditory prompts lessens this deterioration of performance for high-density conditions.
Master of Science

In the driving task, vision, hearing, and the haptic senses are all used by the driver to gather required information. Future Intelligent Transportation Systems components are likely to further increase the volume of information available to or required by the driver, particularly in the case of commercial vehicle operators. The use of alternate modalities to present in-vehicle information is a possible solution to the potential overload of the visual channel. Auditory icons have been shown to improve operator performance and decrease learning and response times, not only in industrial applications, but also as emergency braking warnings. The use of auditory icons in commercial truck cabs has the potential to increase the number of auditory displays that can be distinguished and understood by commercial vehicle operators, and this experiment sought to determine the utility of auditory icons in that situation. Nine auditory icons were evaluated by commercial vehicle operators as they drove an experimental vehicle over public roads. A comparison of the data collected in the truck-cab environment to data collected in a laboratory study on the same auditory icons revealed some differences in the perceived meaning, perceived urgency, and association with the auditory icons' intended meanings between the two conditions. The presence of these differences indicates that driver evaluations of auditory icons can be affected by the environment, and testing should therefore be conducted in a situation that approximates the end-user environment as closely as possible. A comparison of the drivers' brake response times across the three warning conditions (no warning, auditory icon, and soft braking) was also conducted on a closed, secure handling course. Dependent measures included overall brake reaction time and its components, steering response time, time to initial driver action, and categorical measures of driver responses (steering, swerving, braking, and stopping). The results indicated numerically shorter mean response times (on the order of 0.5 seconds for Total Brake Response Time) for the two conditions with warnings, but the differences were not statistically significant. The most likely reason for this lack of significance is the extreme between-subject variability in response times in the no warning condition. An analysis of the response time variance across the three conditions did indicate significantly less variability in operator responses in the two warning conditions. Two of the five dependent measures (Brake Pedal Contact Time and Total Brake Response Time) exhibited significantly reduced variance in the auditory icon warning condition compared to the no warning condition. The soft braking warning condition exhibited significantly reduced variance for four of the dependent measures (Accelerator Reaction Time, Brake Pedal Contact Time, Total Brake Response Time, and First Reaction Time). These results indicate that a soft braking stimulus like that used in this study could potentially prove to be a more effective emergency braking warning than simple auditory warnings alone.
Master of Science

Multi-Attribute Optimisation (MAO) is proposed as a tool for delivering high value products within the systems engineering approach taken in the automotive industry. This work focuses on MAO methods that use Computer Aided Engineering (CAE) analyses to build a metamodel of system behaviour. A review of the literature and current Jaguar Land Rover optimisation methods showed that the number of samples required to build a metamodel could be estimated using the number of input variables. The application of these estimation methods to a concept airbox design showed that this guidance may not be sufficient to fully capture the complexity of system behaviour in the metamodelling method. The use of the number of input variables and their ranges are proposed as a new approach to the scaling of sample sizes. As a corollary to the issue of the sample size required for accurate metamodelling, the sample required to estimate the error was also examined. This found that the estimation of the global error by additional samples may be impractical in the industrial context. CAE is an important input to the MAO process and must balance the efficiency and accuracy of the model to be suitable for application in the optimisation process. Accurate prediction of automotive attributes may require the use of new CAE techniques such as multi-physics methods. For this, the fluid structure interaction assessment of the durability of internal components in the fuel tank due to slosh was examined. However, application of the StarCD-Abaqus Direct couple and Abaqus Combined Eularian Lagrangian was unsuitable for this fuel slosh application. Further work would be required to assess the suitability of other multi-physics methods in an MAO architecture. Application of the MAO method to an automotive airbox shows the potential for improving both product design and lead time.

Over the last three decades, computer architects have been able to achieve an increase in performance for single processors by, e.g., increasing clock speed, introducing cache memories and using instruction level parallelism. However, because of power consumption and heat dissipation constraints, this trend is going to cease. In recent times, hardware engineers have instead moved to new chip architectures with multiple processor cores on a single chip. With multi-core processors, applications can complete more total work than with one core alone. To take advantage of multi-core processors, we have to develop parallel applications that assign tasks to different cores. On each core, pipeline, data and task parallelization can be used to achieve higher performance. Dataflow programming languages are attractive for achieving parallelism because of their high-level, machine-independent, implicitly parallel notation and because of their fine-grain parallelism. These features are essential for obtaining effective, scalable utilization of multi-core processors.

In this thesis work we have parallelized an existing audio codec - Adaptive Multi-Rate Wide Band (AMR-WB) - written in the C language for single core processor. The target platform is a multi-core AMR11 MP developer board. The final result of the efforts is a working AMR-WB encoder implemented in CAL and running in the OpenDF simulator. The C specification of the AMR-WB encoder was analysed with respect to dataflow and parallelism. The final implementation was developed in the CAL Actor Language, with the goal of exposing available parallelism - different dataflows - as well as removing unwanted data dependencies. Our thesis work discusses mapping techniques and guidelines that we followed and which can be used in any future work regarding mapping C based applications to CAL. We also propose solutions for some specific dependencies that were revealed in the AMR-WB encoder analysis and suggest further investigation of possible modifications to the encoder to enable more efficient implementation on a multi-core target system.

Abstract: The purpose of this study was to determine if a correlation exists between suicide and CAG repeat length in Huntington’s disease. Methodology: A case-control study using the COHORT Study de-identified database was conducted. Responses were collected from 163 participants. Depression, substance abuse history and use of benzodiazepines were covariates. Responses to the UHDRS behavioral section pertaining to the frequency and severity of suicidal ideation (“feels life is not worth living”, “has suicidal thoughts”) were analyzed. Results: Despite taking depression, benzodiazepine use, and history of substance abuse into account, there was a predictive relationship between CAG repeat length and frequency of suicidal ideation (p = .010). When the effect of depression was taken into account, there was no significant relationship between CAG repeat length and the severity of suicidal ideation. Recommendations: The findings from this quantitative analysis supported using CAG length in a clinician’s risk factor assessment to determine the frequency of suicidality.

The purpose of this Master thesis was to deepen the knowledge and understanding regarding control parameters for the Extreme Environment Cyclic Testing (EECT) on interior and exterior cab components. The investigated parameters were temperature gradient, length of the warm and cold sections and number of cycles. These parameters were investigated since they control the settings of the Extreme Environment Cyclic Testing. In addition, temperature data was also gathered in order to be analysed along with a simplified case of sun radiation. The method consisted of three parts, where the first part was to perform a literature survey to gather relative data and knowledge. The second part was to perform simulations in COMSOL Multiphysics and the third part consisted of physical testing at Scania and at SP in Borås. To gather temperature data a simulation of a field test was performed in a wind tunnel at Scania. The results displayed a difference of the thermal image of the component when a simplified sun case was compared to a case without applied sun light. Regarding temperatures and temperature gradients it was found that a temperature gradient, based on testing from South Africa, can be up to 2.91°C/min in nature. The temperature results displayed a clear difference between obtained temperatures in a cab compared to results from a car. The angle of the windscreen and the volume difference are believed to be parts of the explanation. The simulations showed that an increase of the temperature gradient to 2°C/min from 1°C/min can be done without changing the time that the temperature of the material is heated respectively cooled significantly. These results were supported from the component testing at Scania which displayed that the difference in strain range when the temperature gradient was changed between 1°C/min to 2°C/min was below 1.2 %, which corresponds to less than 1E-4. The testing at Scania also displayed that the change in maximum strain for different length configurations, 3 h cold 6 h warm, 4 h cold 8 h warm and 6 h cold 12 h warm, could be neglected. The deviation in strain range between the 3h6h and 4h8h configuration was found to be below 1 %, which in absolute terms was 5E-5. It was also showed that the variance of the strain range did not change significant after six cycles. The maximum deviation in strain range between six and ten cycles was 0.15 %. The testing at SP with deformation scans with structural light scans displayed fluctuation in the deformation for the first cycles and a consistent decrease of maximum deformation after 8 cycles. The conclusions from the sun light simulations in COMSOL Multiphysics were that the difference between a simplified sun radiation case with a homogenous ambient temperature and the more realistic one with a set temperature on one surface of the component in combination with a homogenous ambient temperature could be neglected for components with a height up to 0.01 m. This was only valid if the temperature difference was below 10°C. For a larger temperature difference it was found valid for a height up to 0.001 m. Based on the results the author recommends that the control parameters of the Extreme Environment Cyclic Testing are set accordingly to obtain a more efficient testing method:  The number of cycles in the EECT should be 8, since more cycles will not make a significant change on the results  The time should be 3 h in the cold section and 6 h in the warm section  The increase of temperature should be 2°C/min to improve testing efficiency Also, an additional suggestion is to investigate the possibility of a pre-thermal heating phase in the EECT.
Syftet med det här examensarbetet var att utöka kunskapen och förståelsen för kontrollsättande parametrar gällande extrem cyklisk klimatprovning (Extreme Environment Cyclic Testing) för interna och externa hyttkomponenter. Parametrarna som undersöktes var temperaturstigningen, periodlängd och antal cykler. Utöver dessa parametrar samlades temperaturdata in för analys och en jämförelse gjordes mellan ett förenklat fall av solstrålning och ett mer verklighetsbaserat. Metoderna som användes var simuleringar med hjälp av COMSOL Multiphysics, temperaturprovning på Scania och temperaturprovning med scanning med hjälp av strukturerat ljus på SP i Borås. Som komplettering till insamlande av temperaturdata utfördes även en simulering av ett fältprov i vindtunneln på Scania i syfte att utöka mängden temperaturdata. Resultaten visade på en tydlig skillnad av den termiska bilden i en komponent mellan det förenklade fallet av solstrålning och det mer verklighetsbaserade. Gällande temperaturer och temperaturstigning visade analysen av insamlade data från fältprov i Sydafrika att den högsta temperaturstigningen är 2,91°C/min i en naturlig miljö. När jämförelse gjordes mellan insamlad data för en hytt jämfört med data för personbilar visade resultaten på en markant skillnad. Vindrutans vinkel samt hyttens volym anses vara orsaken till att en faktor två kunde observeras för vissa mätpunkter. Resultaten från simuleringarna i COMSOL Multiphysics visade att en temperaturstigning om 2°C/min jämfört med 1°C/min kan användas utan att tiden som materialets temperatur är uppvärmt respektive nerkylt enligt satta minimum och maximum temperaturer i provet ändras markant. Denna trend kunde även påvisas från resultaten av temperaturprovningen på Scania som visade att skillnaden i uppmätt töjningsvidd när temperaturstigningen ändrades från 1°C/min till 2°C/min var lägre än 1,2 %, vilket motsvarar en töjning på 1E-4. Vid analys av provresultaten från Scania konstaterades det att skillnaden i maximal töjning mellan de olika periodkonfigurationerna på 3 h kallt 6 h varmt, 4 h kallt 8 h varmt och 6 h kallt 12 h varmt kunde negligeras. Maximala variationen i töjningsvidd mellan periodkonfiguration 3h6h och 4h8h uppmättes till 1 %, vilket motsvarar 5E-5. Resultaten visade även att variationen i töjningsvidd inte varierade nämnvärt efter sex cykler. Den maximala skillnaden mellan sex och tio cykler var 0,15 %. Provningen på SP där deformationen scannades med hjälp av strukturerat ljus visade på oscillationer under de första cyklerna och att den maximala deformationen minskade efter 8 cykler. Slutsatserna från solsimuleringen i COMSOL Multiphysics var att skillnaden mellan det förenklade fallet när en homogen omgivningstemperatur användes och det mer verklighetstrogna när en högre yttemperatur applicerades på ena sidan i kombination med en homogen omgivningstemperatur kunde försummas för komponenter med en maximal höjd av 0,01 m. Detta om temperaturskillnaden inte översteg 10°C. För en högre temperaturskillnad kunde det bara försummas om komponentens tjocklek var under 0,001 m.  Baserat på resultaten drogs slutsatsen att de kontrollsättande parametrarna för EECT bör sättas enligt följande:                           Antalet cykler bör vara 8 i EECT då fler cykler inte ger nämnvärda skillnader                          Tiden bör vara 3 timmar i den kalla respektive 6 timmar i den varma sektionen                          Temperaturstigningen bör vara 2°C/min för att effektivisera provningen  Dessutom föreslås att man bör undersöka möjligheten att införa ett förvärmningsprov i EECT.