Effective collaboration is essential for engineers at geographically dispersed locations to accomplish good design with less iteration. Over the last several years, more and more efforts have been put into such research as many industries have distributed their product development to locations with knowledge force. This paper presents a collaborative engine to facilitate collaborations among distributed mechanical designs. Using component-based software technology, collaboration functionality is developed into a set of groupware that makes the collaborative engine applicable to develop new collaborative applications or integrate legacy applications into collaborative environments. An XML-based information representation is developed to streamline the information transmission within the distributed environment. A case study is carried out to show how this engine facilitates designers to collaboratively create a 3D solid model of a same part in real time. / Singapore-MIT Alliance (SMA)

The design field of landscape architecture has yet to witness the broad adoption of online education, despite multiple studies that have demonstrated the efficacy of online education in design fields, or distributed design education (DDE), in teaching design. While previous research has focused on the structural, institutional, social, and pedagogical aspects of DDE, little work has focused specifically on barriers to the adoption of DDE from a faculty perspective. This dissertation reports the results of a meta-synthesis of the current literature on DDE and a national Delphi study. A list of the identified constraints of DDE was created through the use of the meta-synthesis. This list of constraints was subsequently used in the creation of the Delphi study to identify the critical barriers to the adoption of online education in landscape architecture. There were 24 barriers assessed during the Delphi study, 7 of which were identified as critical barriers. Findings indicate that faculty remain skeptical of the precedents reported in the literature, do not receive adequate compensation for online course development, and have significant concerns about the ability of online education to replicate the social environment of the design studio. A comparison of the ranked barriers and the most commonly researched constraints suggests that the current research on DDE does not adequately address the concerns of faculty.

In the multidisciplinary design process, design documents are used to help support a team's design and mediate any misunderstandings that occur. Current methods of organizing such design documents are either difficult to keep up to date physically with their digital versions, or inhibit distributed users access to important comparative information. Digital tag and content thumbnail-based document organization is presented as a possible alternative. The effects of tag-based document organization on the manner in which collocated and distributed design teams categorize, review and search design documents and resolve design misunderstandings were compared to the effects of traditional physical (the pin up walls of project rooms)&digital (shared digital file folders) document organization. Student participant design teams were assembled. These teams were observed organizing a provided set of design documents and develop a design solution as a team using either tag-based or traditional physical or digital document organization. Team members were given retrieval tests to compare search times between methods of document organization. User feedback on organization preferences were collected and used to develop a conceptual prototype of a document organization interface supportive of the multidisciplinary design process. Though the quantitative results did no clearly favor tag-based organization, observational results and user comments were in support of the capabilities tag-based organization provides.

For many products, the design process is a complex system involving the interaction of many distributed design activities that need to be carefully coordinated. This research develops a new tool, called a Bayesian network classifier, to improve one specific aspect of this challenge: quantitatively capturing a consensus of which designs are feasible options for meeting system-wide engineering requirements. Classifiers enable designers to independently develop and share maps of the feasible regions of their design space, enabling set-based collaborative design. The method is set-based in that resources are used to thoroughly understand design tradeoffs before commitment is made to a final design. The method is collaborative because the maps are coordinated between design teams to represent the mutually feasible design space of all stake-holders. The benefits are a more thorough understanding of the system-wide design problem across team boundaries as well as knowledge capture for future re-use, potentially leading to faster product development and higher quality products. / text

En conception distribuée, dans la phase du dimensionnement du produit, des incohérences peuvent émerger entre les objectifs de conception et entre les procédures de travail des sous-systèmes hétérogènes. Dans cette phase, les acteurs de conception doivent collaborer d’une manière concourante, car leurs tâches sont reliées les unes aux autres par les couplages de dimensionnement entre leurs sous-problèmes. Les incohérences peuvent provoquer des conflits de conception en raison de ces couplages. La question est de savoir comment obtenir une convergence collaborative pour satisfaire les objectifs globaux et individuels des acteurs de conception lorsque ces acteurs prennent des décisions de conception sous incertitude. L'objectif de cette thèse est de proposer un modèle pour empêcher et résoudre les conflits de conception, tout en surmontant le problème de l'incertitude de la conception avec l'approche de « conception basée sur les ensembles » (SBD). Pour cela, les attitudes de conception sont modélisées avec le paradigme « Croyances-Désirs-Intentions » afin d'explorer les incohérences et gérer les conflits dans les processus de conception. L'approche ascendante conventionnelle est ainsi étendue grâce à des techniques de modélisation multi-agents. Dans cette approche, les agents de conception peuvent fixer des exigences directement sur leurs indicateurs de « bien-être ». Ces indicateurs représentent la manière dont leurs objectifs de conception sont susceptibles d'être satisfaits à un moment donné du processus. Des simulations de Monte Carlo sont effectuées pour évaluer la performance de cette approche, offrant une variété d'attitudes de l'agent. Par rapport aux approches classiques de conception ascendante et descendante, les résultats révèlent moins de conflits de conception et une intensité des conflits réduite. Les techniques de « problème de satisfaction de contraintes » (CSP) et les attitudes de conception sont appliquées pour détecter et justifier des conflits de conception entre les agents hétérogènes. Une nouvelle forme du modèle « Cooperative CSP » (CoCSP) est ainsi mise au point afin de résoudre les conflits de conception en détectant le compromis entre les contraintes. Le système de résolution des conflits peut être adopté grâce à différentes stratégies proposées qui prennent en compte l'architecture de solidarité des agents. Les résultats des simulations montrent que l'intensité des conflits en conception distribuée est réduite par la promotion de la solidarité qui déclenche une aide aux agents en souffrance. / In the product dimensioning phase of a distributed design, inconsistencies can emerge among design objectives as well as among working procedures of heterogeneous subsystems. In this phase, design actors which compose subsystems must collaborate concurrently, since their works are linked to each other through dimensioning couplings among their sub-problems. Inconsistencies through these couplings yield thus to design conflicts. The issue is how to obtain a collaborative convergence to satisfy the global and individual objectives of design actors when making design decisions under uncertainty. The objective of this dissertation is to propose a model for preventing and resolving design conflicts in order to obtain a collaborative convergence, while overcoming the design uncertainty through Set-based Design (SBD). Design attitudes are modeled with Belief-Desire-Intention paradigm to explore inconsistencies and manage conflicts in design processes. The conventional bottom-up approach is thus extended through agent-based attitude modeling techniques. In this approach, design agents can set requirements directly on their wellbeing values that represent how their design targets are likely to be met at a given moment of the design process. Monte Carlo simulations are performed to evaluate the performance of this approach, providing a variety of agent attitudes. Compared to conventional bottom-up and top-down design approaches, the results reveal a fewer number of design conflicts and a reduced aggregated conflict intensity. Constraint satisfaction problem (CSP) techniques and design attitudes are both applied to detect and justify design conflicts of heterogeneous design agents. A novel cooperative CSP (CoCSP) is developed in order to resolve design conflicts through compromising constraint restriction. The conflict resolution system can be adopted for different proposed strategies which take into account the solidarity architecture of design agents. The simulation results show that while promoting solidarity in distributed design by helping agents that suffer, the conflict intensity is reduced, and better design results are obtained.

No description available.

Recent advancements in frequency-agile radio technology and dynamic spectrum access network have created a huge space for improving the utilization efficiency of wireless spectrum. Existing algorithms and protocols, however, have not taken full advantage of the new technologies due to obsolete network design ideologies inherited from conventional network design, such as static spectrum access and static channelization. In this dissertation, we propose new resource management models and algorithms that capitalize on the frequency-agility of next generation radios and the dynamic spectrum access concepts to increase the utilization efficiency of wireless spectrum. We first propose a new analytical model for Dynamic Spectrum Access (DSA) networks. Compared to previous models, the new model is able to include essential DSA mechanisms such as spectrum sensing and primary interference avoidance into solid mathematical representation and thus drastically increase the accuracy of our model. The subsequent numerical study conforms well with existing empirical studies and provides fundamental insights on the design of future DSA networks. We then take advantage of partially overlapped channel in frequency-agile radio networks and propose simple joint channel scheduling and flow routing optimization algorithm that maximizes network throughput. The model quantifies the impact of fundamental network settings, such as node density and traffic load, on the performance of partially overlapped channel based networks. We then propose a cross-layer radio resource allocation algorithm JSSRC (Joint Spectrum Sharing and end-to-end data Rate Control) that iteratively adapts a frequency-agile radio network to optimum with regard to aggregate network spectrum utilization. Subsequently, we extend JSSRC to include routing and present TRSS (joint Transport, Routing and Spectrum Sharing) to solve the much more complex joint transport, routing and spectrum sharing optimization problem. Both JSSRC and TRSS enjoy theoretical convergence and achieve optimum with appropriate scheduling algorithms. The works together strive to improve efficiency of spectrum utilization in frequency-agile radio networks. Numerical and simulation studies show the effectiveness of our designs to reduce the so-called spectrum shortage problem. / Ph. D.

Dissertation (PhD)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The globalisation is increasing the complexity of product development in terms of product variants and the range of technologies implemented. It emphasises the requirement for developing various design information support systems for the world market. However, small and medium enterprises that employ a wide range of design procedures may not be able to afford customised information support systems, with the result that there is a need for flexible, i.e. easily adaptable, design support tools. Four case studies were carried out to investigate the requirements for an information support system aimed at the design process and design documents. They indicated that a design information support system aimed at supporting design teams in the pre-detail mechanical design phases should be able to adapt various design methods and handle design information in a flexible way. Flexible here means being applicable over a wide range of contexts and extendable without affecting data already captured. Ontology based approaches are widely applied where diverse information has to be handled. The development of the Internet today also makes a distributed design approach more and more popular for mechanical design. An internet-based design support system called DiDeas II (Distributed Design assistant) was developed here with an ontologybased approach implemented to provide distributed and flexible assistance during concept generation in small companies. The DiDeas II has separate server side and client side programs, which communicate through a TCP/IP connection. DiDeas II allows design teams to manage their design information according to various design methods, to decrease time-delays and to improve communication between team members. These benefits were confirmed in two case studies carried out to evaluate DiDeas II. Keywords: Distributed design; ontology; concept design, web-based system. / AFRIKAANSE OPSOMMING: Globalisering verhoog die kompleksiteit van produkontwikkeling, in terme van produk variante en die bereik van tegnologieë wat geïmplementeer word. Dit beklemtoon die behoefte om verskeie ontwerp-inligting-ondersteuningstelsels vir die wêreldmark te ontwikkel. Klein en medium ondernemings wat 'n wye spektrum ontwerpsprosedures gebruik, kan egter nie doelgemaakte inligting-ondersteuningstelsels bekostig nie, met die gevolg dat daar 'n behoefte vir maklik-aanpasbare ontwerp ondersteuningstelsels is. Vier gevallestudies is uitgevoer om die vereistes vir 'n inligting-ondersteuningstelsel gemik op die ontwerpproses en ontwerp dokumente, te ondersoek. Dit het aangetoon dat 'n ontwerp-inligting-ondersteuningstelsel, wat ontwerpspanne in die voor-detail meganiese ontwerp fases moet ondersteun, by verskeie ontwerpmetodes moet kan aanpas en ontwerpsinligting op 'n aanpasbare manier kan hanteer. Aanpasbaarheid in hierdie konteks beteken toepaslik oor 'n wye spektrum kontekste en uitbreibaar sonder om data wat alreeds ingevoer is, te beïnvloed. Ontologie-gebaseerde benaderings word wyd toegepas waar diverse inligting hanteer moet word. Die ontwikkeling van die Internet maak 'n verspreide-ontwerpbenadering meer en meer gewild vir meganiese ontwerp. 'n Internet-gebaseerde ontwerpondersteuningstelstel genaamd DiDeas II (Distributed Design assistant) is hier ontwikkel met 'n ontologie-gebaseerde benadering wat daarop gemik is om verspreide, aanpasbare hulp te verleen aan klein maatskappye gedurende konsep- ontwikkeling. Die DiDeas II stelsel het afsonderlike bediener en kliënt programme wat deur 'n TCP/IP verbinding kommunikeer. DiDeas II laat ontwerpspanne toe om hulle ontwerp inligting volgens verskeie ontwerpmetodes te bestuur, tydvertragings te verminder en om kommunikasie tussen spanlede te verbeter. Hierdie voordele is bevestig in twee gevallestudies wat uitgevoer is om DiDeas II te evalueer. Sleutelwoorde: Verspreide ontwerp; ontologie; konsepontwerp; web-gebaseerde stelsel.

Thesis (PhD)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The findings of an investigation into the requirements of a support system for distributed conceptual design in small and medium enterprises are presented. Distributed conceptual design refers to the collaboration of spacially distributed design teams during the early stages of the product development process. Three main elements of a support system were identified. The first element, 'Design Methodology', places a framework for specification development, functional analysis, concept generation and concept evaluation at the designers' disposal. It systematically guides the users through the different steps of the design process. These steps can be performed either alone, or together with other team members. The users are also aided in documenting their steps in order to allow the team members or designers of followup projects to understand the decisions made. The second element, 'Communication and Information Transfer', co-ordinates the communication between the distributed designers and provides a platform for the exchange of design-related data, e.g. customer requirements, ideas, sketches, comments, and decisions. A case study was carried out to assess the use of various tools for communication and information transfer during synchronous and asynchronous collaboration. The case study is described and the results are presented and discussed. Both elements make use of a support service providing various 'Input Devices for Conceptual Design', the third element of a support system. While standard tools such as mouse and keyboard meet the requirements of subsequent stages of the design process, they are often impractical in creating or annotating sketches. Various low-cost input devices were investigated. A framework was developed to integrate the three elements into one support system. The 'Distributed Design Assistant', abbreviated as 'DiDeas', is an Internet-based system that allows simultaneous multi-user collaboration. A relational database is located on a central web-server and stores all design information entered into the system. The user interface was realized in the form of a collection of Microsoft Active Server Pages, which can be accessed platform-independently via a standard webbrowser. The development of the database structure and of the user interface is described in detail. A second case study was carried out to evaluate the Distributed Design Assistant. The case study is described and the results are presented and discussed. The low-cost system has proven to be a very useful tool for distributed conceptual design. The Distributed Design Assistant systematically guides novice and experienced designers through the stages of specification development and conceptual design. It facilitates the easy collection and the fast exchange of a large amount of textual and graphical information during these stages. Although the system is relatively simple, compared to professional product data management systems used in later stages of the design process, it strongly enhances the productivity of designers and distributed design teams. Keywords: Distributed Design, Conceptual Design, Systematic Product Development / AFRIKAANSE OPSOMMING: Die bevindinge van 'n ondersoek na die behoeftes van 'n ondersteuningstelsel VIr verspreide konsepsionele ontwerp in klein en medium ondernemings word aangebied. Verspreide konsepsionele ontwerp is die saamwerk van ruimtelik verspreide ontwerp spanne gedurende die aanvanklike fases van die produk ontwikkelingsproses. Drie hoof elemente van 'n ondersteuningstelsel is geïdentifiseer. Die eerste element, 'Ontwerpmetodiek' stel 'n raamwerk vir spesifikasie ontwikkeling, funksionele analise, konsep generasie en konsep beoordeling tot beskikking van die ontwerpers. Dit lei die gebruikers stelselmatig deur die verskillende stappe van die ontwikkelingsproses. Die stappe kan of alleen of tesame met ander lede van die span uitgevoer word. Die gebruiker word ook ondersteun met die dokumentasie van die stappe sodat die lede of ontwerpers van opvolgprojekte die besluite wat gemaak is, kan begryp. Die tweede element, 'Kommunikasie en Informasie Oordrag', koordineer die kommunikasie tussen die verspreide ontwerpers en bied 'n platvorm vir die uitruil van ontwerpinformasie, byvoorbeeld kliënte behoeftes, idees, sketse, kommentaar en besluite. 'n Gevallestudie is uitgevoer om die gebruik van verskeie gereedskapstukke vir kommunikasie en informasie-oordrag gedurende sinchrone en asinchrone samewerking te beoordeel. Die gevalle studie is beskryf en die resultate is bespreek. Altwee elemente maak gebruik van 'n ondersteuningsdiens wat verskeie 'Invoergereedskap vir Konsepsionele Ontwerp' voorsien, die derde element van die ondersteuningstelsel. Terwyl standard gereedskap, byvoorbeeld 'n rekenaar muis en sleutelbord, die behoeftes van die latere ontwerpsfases bevredig, is hulle dikwels onprakties vir die maak van sketse en byskrifte. Verskeie laekoste invoergereedskap is ondersoek. 'n Raamwerk is ontwikkel om die drie elemente in een ondersteuningstelsel te integreer. Die 'Distributed Design Assistant', verkort 'DiDeas', is 'n Internet-gebaseerde stelsel wat sinchrone multi-gebruiker samewerking moontlik maak. 'n Gekoppelde databasis is op 'n sentrale webbediener geplaas en versamel al die ontwerpinformasie wat in die stelsel ingevoer is. Die gebruikerintervlak is geskep as 'n versameling van Microsoft Active Server Pages. Toegang tot die stelsel is onafhanklik van die rekenaar bedryfstelsel en kan verkry word met 'n standard webblaaier. Die ontwikkeling van die databasisstruktuur en van die gebruikerintervlak is in detail beskryf. 'n Tweede gevallestudie is uitgevoer om die Distributed Design Assistant te beoordeel. Die gevallestudie is beskryf en die resultate is bespreek. Die laekoste stelsel het homself bewys as 'n baie nuttige werktuig VIr verspreide konsepsionele ontwerp. Die Distributed Design Assistant lei nuweling en ervare ontwerpers stelselmatig deur die spesifikasie ontwikkeling en konsepsionele ontwerp stappe. Dit fasiliteer die maklike versameling en die vinnige uitruil van 'n groot hoeveelheid teks en grafiese informasie gedurende hierdie stappe. Ofskoon die stelsel relatief eenvoudig is in vergelyking met professionele produkdata-bestuurstelsels, verhoog dit die produktiwiteit van ontwerpers en verspreide ontwerp spanne aansienlik.

Developing process plans and part programs rapidly and correctly for CNC machine tools plays a vital role in manufacturing. This study is concerned with the development of a web-enabled virtual design and manufacturing application system for rotational parts. The object oriented methodology is used in the application development. Windows Distributed interNet Application (DNA) architecture which describes a framework of building software technologies in an integrated web and client-server model of computing, is employed in the system. The entire system was modeled with Unified Modeling Language (UML), which is an industry-standard visual modeling notation to express software development architectures. Feature-based design approach, being a practical way of linking the design with manufacturing, is implemented in the rotational part design. Users have to be registered in order to use the system. With the supplied web site, users can easily register to system. After registration, the user obtains a password and a unique username. Upon the user authentication, the user session starts. A typical user session involves new or past project selection, material selection, part sketching, blank size definition and cutting parameters determination. After all the steps are completed, process plan and part-program, which are required to manufacture the part on Denford Mirac CNC Turning Machine are generated and displayed on the web site and then saved to the database. The application enables the users to see past projects and to generate new process plan and part programs for different cutting parameters. The process plan, part program and the 2D wire frame drawing of the corresponding part are demonstrated on the web site for the chosen projects.