No description available.

Complex assembly systems are made up of hundreds, and in some cases, thousands of parts, that all need to be managed in a proper manner so part arrivals will coincide to meet a build plan, and ensure production requirements are satisfied. A major challenge faced by manufacturers for these complex systems is that many parts have long and complex supply chains, which result in long and highly variable supply lead times. The high cost and low volume makes holding large stocks of these components unviable. Thus, the need arises for the development of a simulation tool that can predict the time all of the required parts are ready for assembly, and allow for comparison of various ordering and inventory strategies. Two strategies were tested, the current practice of ordering to an agreed upon quoted lead time, and a strategy which accounts for lead time variability through advanced ordering. The results of these two strategies displayed the benefits of synchronizing the system through advance ordering, as a potential 60% reduction in inventory was observed. Future development in the tool would incorporate more granular steps of the build sequence, as well as the inclusion of quality non-conformance (QN) issues.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-04-17T21:35:20Z No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-04-18T22:34:50Z (GMT) No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) / Made available in DSpace on 2017-04-18T22:34:50Z (GMT). No. of bitstreams: 1 DanielAlencarDaCosta_TESE.pdf: 9198560 bytes, checksum: 463f875eda2671bd33beca615f72eef3 (MD5) Previous issue date: 2017-02-08 / The timely delivery of addressed software issues (i.e., bug fixes, enhancements, and new features) is what drives software development. Previous research has investigated what impacts the time to triage and address (or fix) issues. Nevertheless, even though an issue is addressed, i.e., a solution is coded and tested, such an issue may still suffer delay before being delivered to end users. Such delays are frustrating, since end users care most about when an addressed issue is available in the software system (i.e, released). In this matter, there is a lack of empirical studies that investigate why addressed issues take longer to be delivered compared to other issues. In this thesis, we perform empirical studies to understand which factors are associated with the delayed delivery of addressed issues. In our studies, we find that 34% to 98% of the addressed issues of the ArgoUML, Eclipse and Firefox projects have their integration delayed by at least one release. Our explanatory models achieve ROC areas above 0.74 when explaining delivery delay.We also find that the workload of integrators and the moment at which an issue is addressed are the factors with the strongest association with delivery delay.We also investigate the impact of rapid release cycles on the delivery delay of addressed issues. Interestingly, we find that rapid release cycles of Firefox are not related to faster delivery of addressed issues. Indeed, although rapid release cycles address issues faster than traditional ones, such addressed issues take longer to be delivered.Moreover, we find that rapid releases deliver addressed issues more consistently than traditional ones. Finally, we survey 37 developers of the ArgoUML, Eclipse, and Firefox projects to understand why delivery delays occur. We find that the allure of delivering addressed issues more quickly to users is the most recurrent motivator of switching to a rapid release cycle.Moreover, the possibility of improving the flexibility and quality of addressed issues is another advantage that are perceived by our participants. Additionally, the perceived reasons for the delivery delay of addressed issues are related to decision making, team collaboration, and risk management activities. Moreover, delivery delay likely leads to user/developer frustration according to our participants. Our thesis is the first work to study such an important topic in modern software development. Our studies highlight the complexity of delivering issues in a timely fashion (for instance, simply switching to a rapid release cycle is not a silver bullet that would guarantee the quicker delivery of addressed issues).

Distributed event processing systems suffer from poor scalability and inefficient resource usage caused by load distributions typical in real-world applications. The results of these shortcomings are availability issues, poor system performance, and high operating costs. This thesis proposes three remedies to solve these limitations in content-based publish/subscribe, which is a practical realization of an event processing system. First, we present a load balancing algorithm that relocates subscribers to distribute load and avoid overloads. Second, we propose publisher relocation algorithms that reduces both the load imposed onto brokers and delivery delay experienced by subscribers. Third, we present ``green" resource allocation algorithms that allocate as few brokers as possible while maximizing their resource usage efficiency by reconfiguring the publishers, subscribers, and the broker topology. We implemented and evaluated all of our approaches on an open source content-based publish/subscribe system called PADRES and evaluated them on SciNet, PlanetLab, a cluster testbed, and in simulations to prove the effectiveness of our solutions. Our evaluation findings are summarized as follows. One, the proposed load balancing algorithm is effective in distributing and balancing load originating from a single server to all available servers in the network. Two, our publisher relocation algorithm reduces the average input load of the system by up to 68%, average broker message rate by up to 85%, and average delivery delay by up to 68%. Three, our resource allocation algorithm reduces the average broker message rate even further by up to 92% and the number of allocated brokers by up to 91%.

Distributed event processing systems suffer from poor scalability and inefficient resource usage caused by load distributions typical in real-world applications. The results of these shortcomings are availability issues, poor system performance, and high operating costs. This thesis proposes three remedies to solve these limitations in content-based publish/subscribe, which is a practical realization of an event processing system. First, we present a load balancing algorithm that relocates subscribers to distribute load and avoid overloads. Second, we propose publisher relocation algorithms that reduces both the load imposed onto brokers and delivery delay experienced by subscribers. Third, we present ``green" resource allocation algorithms that allocate as few brokers as possible while maximizing their resource usage efficiency by reconfiguring the publishers, subscribers, and the broker topology. We implemented and evaluated all of our approaches on an open source content-based publish/subscribe system called PADRES and evaluated them on SciNet, PlanetLab, a cluster testbed, and in simulations to prove the effectiveness of our solutions. Our evaluation findings are summarized as follows. One, the proposed load balancing algorithm is effective in distributing and balancing load originating from a single server to all available servers in the network. Two, our publisher relocation algorithm reduces the average input load of the system by up to 68%, average broker message rate by up to 85%, and average delivery delay by up to 68%. Three, our resource allocation algorithm reduces the average broker message rate even further by up to 92% and the number of allocated brokers by up to 91%.

La presente tesis es una “Propuesta de mejora del proceso de planificación de proyectos en una empresa de construcción con sistema drywall” desarrollada en una PYME del rubro construcción. La propuesta está basada en herramientas de ingeniería para contrarrestar el problema identificado en la empresa en estudio que es la demora en la entrega de proyectos de construcción. Para ello, en la presente tesis está estructurada en 6 capítulos. En el capítulo 1 se presenta el Marco teórico, en el cual se define el sistema constructivo drywall, metodologías y herramientas de mejora aplicables al proceso de planificación de proyectos de construcción y a la reducción y/o eliminación de demora en la entrega al cliente. En el capítulo 2 se presenta el diagnóstico, en el cual se describe la empresa, las condiciones en las que opera, el problema, los procesos involucrados con el problema, causas raíces, impacto económico y las herramientas aplicables a la reducción y/o eliminación del problema. En el capítulo 3 se desarrolla la evaluación de alternativas de solución, en el cual se describe el plan de implementación de las herramientas 5S y Last Planner System. En el capítulo 4 se muestra la validación de la propuesta de mejora compuesta por juicio experto y la validación económica. En el capítulo 5, se muestra el impacto de la mejora en los stakeholders mediante una matriz Leopold. Finalmente, en el capítulo 6 se muestran las conclusiones y recomendaciones de la presente tesis. / This thesis is a "Proposal for improvement of the project planning process in a construction company with gypsum panel system" developed in an SME of the construction sector. The proposal is based on engineering tools to counteract the problem in the company in the study that is the delay in the delivery of construction projects. For this, in this thesis is structured in 6 chapters. Chapter 1 presents the theoretical framework, which defines the construction system of drywall, methodologies and tools to improve the planning process of construction projects and the reduction and / or elimination of the delay in delivery to the client. In chapter 2 the diagnosis is presented, in which the company is described, the conditions in which it operates, the problem, the processes related to the problem, the root causes, the economic impact and the tools applicable to the reduction and / or the elimination of the problem. Chapter 3 describes the evaluation of solution alternatives, and describes the implementation plan of the 5S and Last Planner System tools. Chapter 4 shows the validation of the improvement proposal composed of expert judgment and economic validation. In Chapter 5, the impact of the improvement on stakeholders is shown through a Leopold matrix. Finally, chapter 6 shows the conclusions and recommendations of this thesis. / Tesis