Performance Analysis of An Experimental Micro Flexible Manufacturing System (FMS)

Due to advanced technology, it is very important the performance of FMS for sensivity, production quality, repeatability and energy consumptions. Flexible manufacturing systems (FMSs) are the most automated and technologically sophisticated of the machine cell types used to implement cellular manufacturing. An FMS usually has multiple automated stations and is capable of variable routings among stations, while its flexibility allows it to operate as a mixed model system. The FMS concept integrates many of the advanced technologies that we met in previous units, including flexible automation, CNC machines, distributed computer control, and automated material handling and storage. In this experimental investigation, vibration and accelerations analysis of an experimental FMS with 5 degrees of freedom robot manipulator are presented. Firstly, experimental measurement of accelerations and vibrations are trained with a vibration measurement system and sensors. However, the process of production of part is a cycle of exact production time

Destination Tag Routing Techniques Based on a State Model for the IADM Network

A state model is proposed for solving the problem of routing and rerouting messages in the Inverse Augmented Data Manipulator (IADM) network. Using this model, necessary and sufficient conditions for the reroutability of messages are established, and then destination tag schemes are derived. These schemes are simpler, more efficient and require less complex hardware than previously proposed routing schemes. Two destination tag schemes are proposed. For one of the schemes, rerouting is totally transparent to the sender of the message and any blocked link of a given type can be avoided. Compared with previous works that deal with the same type of blockage, the timeXspace complexity is reduced from O(logN) to O(1). For the other scheme, rerouting is possible for any type of link blockage. A universal rerouting algorithm is constructed based on the second scheme, which finds a blockage-free path for any combination of multiple blockages if there exists such a path, and indicates absence of such a path if there exists none. In addition, the state model is used to derive constructively a lower bound on the number of subgraphs which are isomorphic to the Indirect Binary N-Cube network in the IADM network. This knowledge can be used to characterize properties of the IADM networks and for permutation routing in the IADM networks

Redes de interconexión: contribución al estudio de su vulnerabilidad

Esta tesis se ha centrado en el estudio de la vulnerabilidad del encaminamiento en familias de grafos y dígrafos que resultan particularmente interesantes por su aplicación al diseño de redes de interconexión: redes asociadas con teselaciones del plano, dígrafos línea parciales de Kautz y de Brujin. Se demuestra la existencia de vértices (p,f)-centrales en los grafos de doble y triple lazo para determinados f y se determinan conjuntos de vértices y conjuntos de ramas que pueden fallar sin que se pierda la comunicación entre los restantes en las dos familias anteriores y en los dígrafos bipartitos bd (s,b,c,d). Este estudio se hace a partir de la representación geométrica que representan estas redes asociadas a teselaciones del plano.También se da un método que construye toda la sucesión finita de dígrafos línea parciales de Kautz y de Brujin presentando un algoritmo que calcula vértices (p,f)-centrales en estas redes

Efficient runtime placement management for high performance and reliability in COTS FPGAs

Designing high-performance, fault-tolerant multisensory electronic systems for hostile environments such as nuclear plants and outer space within the constraints of cost, power and flexibility is challenging. Issues such as ionizing radiation, extreme temperature and ageing can lead to faults in the electronics of these systems. In addition, the remote nature of these environments demands a level of flexibility and autonomy in their operations. The standard practice of using specially hardened electronic devices for such systems is not only very expensive but also has limited flexibility. This thesis proposes novel techniques that promote the use of Commercial Off-The- Shelf (COTS) reconfigurable devices to meet the challenges of high-performance systems for hostile environments. Reconfigurable hardware such as Field Programmable Gate Arrays (FPGA) have a unique combination of flexibility and high performance. The flexibility offered through features such as dynamic partial reconfiguration (DPR) can be harnessed not only to achieve cost-effective designs as a smaller area can be used to execute multiple tasks, but also to improve the reliability of a system as a circuit on one portion of the device can be physically relocated to another portion in the case of fault occurrence. However, to harness these potentials for high performance and reliability in a cost-effective manner, novel runtime management tools are required. Most runtime support tools for reconfigurable devices are based on ideal models which do not adequately consider the limitations of realistic FPGAs, in particular modern FPGAs which are increasingly heterogeneous. Specifically, these tools lack efficient mechanisms for ensuring a high utilization of FPGA resources, including the FPGA area and the configuration port and clocking resources, in a reliable manner. To ensure high utilization of reconfigurable device area, placement management is a key aspect of these tools. This thesis presents novel techniques for the management of hardware task placement on COTS reconfigurable devices for high performance and reliability. To this end, it addresses design-time issues that affect efficient hardware task placement, with a focus on reliability. It also presents techniques to maximize the utilization of the FPGA area in runtime, including techniques to minimize fragmentation. Fragmentation leads to the creation of unusable areas due to dynamic placement of tasks and the heterogeneity of the resources on the chip. Moreover, this thesis also presents an efficient task reuse mechanism to improve the availability of the internal configuration infrastructure of the FPGA for critical responsibilities like error mitigation. The task reuse scheme, unlike previous approaches, also improves the utilization of the chip area by offering defragmentation. Task relocation, which involves changing the physical location of circuits is a technique for error mitigation and high performance. Hence, this thesis also provides a functionality-based relocation mechanism for improving the number of locations to which tasks can be relocated on heterogeneous FPGAs. As tasks are relocated, clock networks need to be routed to them. As such, a reliability-aware technique of clock network routing to tasks after placement is also proposed. Finally, this thesis offers a prototype implementation and characterization of a placement management system (PMS) which is an integration of the aforementioned techniques. The performance of most of the proposed techniques are tested using data processing tasks of a NASA JPL spectrometer application. The results show that the proposed techniques have potentials to improve the reliability and performance of applications in hostile environment compared to state-of-the-art techniques. The task optimization technique presented leads to better capacity to circumvent permanent faults on COTS FPGAs compared to state-of-the-art approaches (48.6% more errors were circumvented for the JPL spectrometer application). The proposed task reuse scheme leads to approximately 29% saving in the amount of configuration time. This frees up the internal configuration interface for more error mitigation operations. In addition, the proposed PMS has a worst-case latency of less than 50% of that of state-of- the-art runtime placement systems, while maintaining the same level of placement quality and resource overhead

Production planning process optimization

Produktionsautomationssysteme sind komplexe Systeme mit viele Entitäten (Roboter, Transportsysteme usw.) die mannigfaltig aufeinander einwirken und zusammenspielen um das Ziel einer Produktendfertigung zu ermöglichen. Multiagenten-Systeme basierend auf verteilter Kontrolle sind der praktikabelste Ansatz die ansteigende Kompliziertheit solcher Systeme in den Griff zu bekommen und gleichzeitig eine flexible Anpassung des Produktionsautomationssystems an variable Rahmenbedingungen zu gewährleisten (z.B. Änderung von Produktionsstrassen oder die Koordination von Transportelementen). Für solch kritische Produktionsautomationssysteme ist eine Überprüfung aller Schritte im Entwicklungsprozess erforderlich um ein sicher funktionierendes System zu gewährleisten. Qualitätsmessungen zur Sicherstellung der Korrektheit von Systemelemente stellen bei der Zielerreichung daher einen wichtigen Schritt dar. Die Softwaresimulation des Werkstatt-Systems erlaubt sowohl Leistungsmessung einer Systemkonfiguration als auch schnellere und preiswertere Reaktion auf sich ändernde Voraussetzungen. Hinzu kommt, dass die Softwaresimulation von Produktionsautomationssystemen immer mehr einen praktikable Möglichkeit darstellt, um Produktionsvorgänge zu planen und/oder zu optimieren.Production Automation Systems are complex systems. They typically have many entities like robots, transport systems, etc. that interact in complex ways to provide production automation functions like assembly of products. The increasing complexity of these systems makes central control more and more difficult. Therefore systems with distributed control are areas of intense research such as multi-agent systems. Moreover, changing requirements for production automation systems require better system and model flexibility for e.g. easy-to-change workshop layouts or coordination of transportation elements. Meeting all this tasks makes the design of a production automation system a challenge hard to solve for designers and system engineers. For safety-critical systems like production automation systems, verification is required for all steps in the development process. Testing aims at measuring the quality of executable system elements, especially the validity of a configuration and correctness of calculated results. A particular challenge is measurement of non-functional quality requirements such as system performance before the actual hardware system is built. Software simulation of the workshop system would allow both performance measurement of a configuration and faster, cheaper reaction to changing requirements, however the validity of the simulation has to be assured. On top of this, software simulation of production automation systems can get more and more a sufficient part during the production planning and optimization process

Behavioural reactions of managers towards airline operations performance in times of crisis and growth.

This research was undertaken in the United States within two different regional airlines and examines the attitudes and behaviours of managers to operations performance measurement and review (PMR) systems during separate periods of crisis and growth. The aim and objectives were to examine whether managers would consciously adopt the necessary attitudes and behaviours that are required to positively interact with a PMR system and to further examine what these behaviours should be. A secondary aim was to understand whether the prevailing business state of crisis or growth affected the attitudes and behaviours of managers as they used the PMR system. The research spanned seven years and was conducted over four iterative cycles within an Action Research paradigm and used semi-structured interviews and repertory grids to examine individual personal construct systems. The research is essentially qualitative but draws on quantitative techniques where appropriate. The research has shown that people do not automatically adopt the behaviours necessary to achieve performance goals. Unless there is structure, support and an inherent commitment to training managers on how to, correctly, interpret operations performance data then there is likely to be an uncommitted and uninformed response to the PMR system. The research has confirmed that both business states of crisis and growth can have a positive impact on some people and encourage them to adopt performance-driven behaviour

Simulation-based support for integrated design of new low-energy office buildings

This thesis reports on four years of research with the aim to contribute to the implementation of low-energy office buildings with high quality of indoor environment and good total economy. Focus has been on the design decisions made in the early stages of the building design process. The objective is to contribute to a development where simulations of building energy performance and indoor environment is used for generating an input to the overall building design process prior to any actual form giving of the building. This input should be considered as one of several similar inputs from other building design disciplines (structural, fire, architecture etc.) to the integrated building design process. The research therefore revolves around the hypothesis that parametric analyses on the energy performance, indoor environment and total economy of rooms with respect to geometry and characteristics of building elements and services can be used to generate a useful input to the early stage of an integrated building design process. To pursue a corroboration of this hypothesis, a method for making informed decisions when establishing the input to the overall building design process is proposed. The method relies on the use of building simulation to illustrate how design parameters will affect the energy performance and the quality of the indoor environment prior to any actual design decision. The method is made operational in a simple building simulation tool capable of performing integrated performance predictions of energy consumption, thermal indoor environment, indoor air quality, and daylight levels. The tool has been tested extensively throughout the four year period of this project. The feedback from these tests has been used to develop the operability and usability of the tool. The end result is a tool which, with minor reservations, has proved to be operational and useful in the design of low-energy office buildings with good indoor environment. The conducted research is reported in the main body of this thesis and in three papers for scientific journals. An abstract of these is given in the following. Article I The early stages of building design include a number of decisions which have a strong influence on the performance of the building throughout the rest of the process. It is therefore important that designers are aware of the consequences of these design decisions. This paper presents a method for making informed decisions in the early stages of building design to fulfil performance requirements with regard to energy consumption and indoor environment. The method is operationalised in a program that utilises a simple simulation program to make performance predictions of user-defined parameter variations. The program then presents the output in a way that enables designers to make informed decisions. The method and the program reduce the need for design iterations, reducing time consumption and construction costs, to obtain the intended energy performance and indoor environment. Paper published in Energy and Buildings 42 (7) (2010), 1113-1119. doi:10.1016/j.enbuild.2010.02.002 Article II A method for simulating predictive control of building systems operation in the design stage is presented. The predictive control method uses building simulation based on weather forecasts to predict whether there is a future heating or cooling requirement. This information enables the thermal control systems of the building to respond proactively to keep the operational temperature within the thermal comfort range with the minimum use of energy. The method is assuming perfect weather prediction and building modelling because of the design situation. The method is implemented in an existing building simulation tool. A test case featuring an office located in Copenhagen, Denmark, shows that the suggested method reduces the energy required for heating and ventilation compared to more conventional control systems, while improving thermal comfort for building occupants. The method furthermore automates the configuration of buildings systems operation. This eliminates time consuming manual configuration of building systems operation when using building simulation for parametric analyses in the design phase. Applied Energy 88 (2011) 4597–4606. doi:10.1016/j.apenergy.2011.05.053 Article III Increasing requirements for energy performance in new buildings mean the cost of incorporating energy-saving in buildings is also increasing. Building designers thus need to be aware of the long-term cost-effectiveness of potential energy-conserving measures. This paper presents a simplified and transparent economic optimisation method to find an initial design proposal near the economical optimum. The aim is to provide an expedient starting point for the building design process and more detailed economic optimisation. The method uses the energy frame concept to express the constraints of the optimisation problem, which is then solved by minimising the costs of conserving energy in all the individual energy-saving measures. A case example illustrates how the method enables designers to establish a qualified estimate of an economically optimal solution. Such an estimate gives a good starting point for the iterative design process and a more detailed economic optimisation. Furthermore, the method explicitly illustrates the economic efficiency of the individual building elements and services enabling the identification of potentials for further product development. Paper published in Renewable Energy 38(1) (2012) 173-180. doi:10.1016/j.renene.2011.07.01