In 1996, a concept was proposed by the UK Ministry of Defence with the intention of making the field of reliability more useful to the end user, particularly within the field of military aerospace. This idea was the Maintenance Free Operating Period (MFOP), a duration of time in which the overall system can complete all of its required missions without the need to undergo emergency repairs or maintenance, with a defined probability of success. The system can encounter component or subsystem failures, but these must be carried with no effect to the overall mission, until such time as repair takes place. It is thought that advanced technologies such as redundant systems, prognostics and diagnostics will play a major role in the successful use of MFOP in practical applications. Many types of system operate missions that are made up of several sequential phases. For a mission to be successful, the system must satisfactorily complete each of the objectives in each of the phases. If the system fails or cannot complete its goals in any one phase, the mission has failed. Each phase will require the system to use different items, and so the failure logic changes from phase to phase. Mission unreliability is defined as the probability that the system fails to function successfully during at least one phase of the mission. An important problem is the efficient calculation of the value of mission unreliability. This thesis investigates the creation of a modelling method to consider as many features of systems undergoing both MFOPs and phased missions as possible. This uses Petri nets, a type of digraph allowing storage and transit of tokens which represent system states. A simple model is presented, following which, a more complex model is developed and explained, encompassing those ideas which are believed to be important in delivering a long MFOP with a high degree of confidence. A demonstration of the process by which the modelling method could be used to improve the reliability performance of a large system is then shown. The complex model is employed in the form of a Monte-Carlo simulation program, which is applied to a life-size system such as may be encountered in the real world. Improvements are suggested and results from their implementation analysed.

This master’s thesis is aimed at the lubrication of machina tools. There are described the basic type sof lubrication systems, design of maintenance-free lubricated vertical lathe and technical-economic evaluation. The last section is devoted to the design proces.

Symptoms of harsh environments create pressure on autonomous machines to work wellwith the use of measurement devices. Sensors used within construction equipment vehiclessuffer from being covered with fogs of dirt, oil, water, and dust. Autonomous vehicle’sdependency on fully functional sensors paves roads for research to be made on ways to keepsensor data from being compromised and automation to be improved.In cooperation with Dynapac Compaction Equipment AB, this master’s thesis problemopted for innovative and sustainable product development to tackle the problem. The thesiscomprises of 30 credits. In this thesis, work will be done emphasizing on ways to keepautonomous performance at peak for construction equipment vehicles with low to no capacityfor sophisticated equipment and supply of power and water. For reference, the project targetsasphalt rollers due to their relevance at Dynapac.With the use of innovative product development tools, the problem is to be tackled with anengineering approach revolving around the design thinking process. All progress will beconstituted at Dynapac’s facilities in Karlskrona. Interviews and dialogue with relevantindividuals are to be held to create value based on customer needs which has been of highpriority and is to be iteratively monitored throughout the project. Prototyping will play a partwith large amount of testing to prove concept, including processes of 3dmodeling andmanufacturing of components.With measurement incorrections reaching up to 80 degrees out of a measurement spanwithin the range of 0 to 150 degrees, three concepts have been established, each of which areequipment neutral to benefit construction vehicles which has shown to be valuable within theindustry.A pipe concept which’s purpose is to hide the sensor further and create distance betweensensor lens and measurement surface has been established. The concept is feasible for theconstruction industry, protects the sensor from debris and supports autonomous systems.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of this thesis is to compare the aviation derived reliability metric known as the Maintenance Free Operating Period (MFOP), with the traditionally used, and commonly found, reliability metric Mean Time Between Failure (MTBF), which has over the years shown some innate disadvantages in the field of maintenance. It will be shown that this is mainly due to MTBF’s inherent acceptance of failure and the unscheduled maintenance therewith directly connected. Moreover, MFOP is successfully applied to a mining specific case study, as to date, no other application of the MFOP concept to the mining sector is known. An extensive literature study is presented, which covers concepts relevant to the overall study and which helps to contextualise the problem, revealing the major shortcomings of the commonly accepted MTBF metric. A methodology to analyse systems MFOP performance, making use of failure statistics to analyse both repairable and non-repairable systems, is presented. Validation makes use of a case study which applies the MFOP methodology to a system, specifically in the mining sector. It was shown that MFOP could be applied to the data obtained from the mining sector, producing estimates which were accurate representations of reality. These findings provide an exciting basis on which to begin to facilitate a paradigm shift in the mind set of maintenance personnel, setting reliability targets and dealing with unscheduled maintenance stops. KEYWORDS: Maintenance Free Operating Period, Mean Time Between Failure, Maintenance, Mining / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om die Onderhoudvrye Bedryf Tydperk (OBT), ’n betroubaarheidsmaatstaf afkomstig van die lugvaart industrie, te vergelyk met die Gemiddelde Tyd Tussen Falings (GTTF) maatstaf wat tradisioneel in algemene gebruik is, maar wat oor die jare inherente nadele met betrekking tot instandhouding geopenbaar het. Dit sal bewys word dat hierdie nadele hoofsaaklik ontstaan as gevolg van die GTTF se inherente aanvaarding van failure en die ongeskeduleerde instandhouding wat daarmee gepaard gaan. OBT word ook suksesvol aangewend in ’n mynwese-spesifieke gevallestudie, wat aaangegaan is aangesien geen ander sooortgelyke aanwending in die mynwese sektor tot datum bekend is nie. ’n Breedvoerige literatuurstudie word voorgelê wat relevante konsepte dek en die probleem binne konteks plaas, en daardeur die hoof tekortkominge van die algemeen aanvaarde GTTF metriek ontbloot. ’n Metodologie waardeur analise van die stelsel werkverrigting van die OBT uitgevoer kan word met gebruik van onderbrekings statistiek om herstelbaar sowel as onherstelbare stelsels te analiseer, word voorgestel. Geldigheid word getoets deur ’n gevallestudie wat die OBT metodologie aangewend word spesifiek vir ’n stelsel in die mynwese Dit is bewys dat OBT toegepas kan word op data afkomstig van die mynwese sector, en skattings lewer wat akkurate voorstellings is van die werklikheid. Hierdie bevindinge is opwindend, en dit dien as die basis vir ’n die aanwending van ’n paradigmaskuif in die benadering van instandhoudingspersoneel tot die daarstelling van teikens vir betroubaarheid en ook in hul hantering van ongeskeduleerde instandhoudingsophoud. SLEUTELWOORDE: Onderhoudvrye Bedryf Tydperk, Gemiddelde Tyd Tussen Falings, Onderhoud, Mynbou

For the transport of their spacecraft from the vehicle assembly building to the launch pads at Kennedy Space Centre, Florida, the National Aeronautics and Space Administration (NASA) is using two special crawler transporters since 1965. First developed for the Saturn V rocket the crawler transporters have been sufficient for all following generations of space ships so far. But for the new generation of Orionspacecraft which is under development now, a load capacity increase for the crawler transporter of plus 50% was necessary. For this task Hunger Hydraulik did develop new jacking, equalizing and levelling (JEL) cylinders with sufficient load capacity but also with some new features to improve the availability, reliability and safety of this system. After design approval and manufacture of the cylinders they have been tested in a special developed one-to-one scale dynamic test rig and after passing this the cylinders had to prove their performance in the crawler transporter itself. This article describes the general application and introduces the technical requirements of this project as well as the realized solution.

Die Nutzung von Umgebungsenergie ermöglicht bei einer zunehmenden Anzahl von Anwendungen drahtloser Sensorknoten eine autarke Energieversorgung. Wartungseingriffe sowie unvorhergesehene Energieengpässe begrenzen den autarken Einsatz derartiger Sensorknoten oder erfordern eine deutliche Überdimensionierung der Energy Harvester und Energiespeicher. Anwendungen, wie der Einsatz in unzugänglichen Bereichen, Sensornetzwerken mit einer großen Anzahl von Knoten oder sehr kleinen Knoten / Smart Dust, können unwirtschaftlich werden, wenn kein wartungsfreier Betrieb gewährleistet werden kann. Erreicht ein drahtloser Sensorknoten einen energetisch niedrigen Zustand, ist es für einen erneuten Start erforderlich, dass zusätzlich zu einer ausreichenden Spannung genügend Energie für den Startvorgang zur Verfügung steht. Bei zu zeitiger Aktivierung wird der Startvorgang aufgrund der einbrechenden Spannung nicht abgeschlossen und verhindert die Aufnahme des Betriebs. Ein Voltage Supervisor wird benötigt, um den Startvorgang so lange zu verzögern, bis ausreichend Energie für diesen zur Verfügung steht. Im Rahmen der vorliegenden Arbeit wird ein Voltage Supervisor für das Energiemanagement umgebungsenergieversorgter Sensorknoten vorgeschlagen. Die Herausforderungen liegen in der Realisierung einer definierten Abschalt- und Startcharakteristik, auch bei langsamen oder variablen Spannungsanstiegen, in der Implementierung einer Kaltstartfähigkeit und im zuverlässigen Schaltverhalten unter widrigen Umgebungsbedingungen oder niedrigem Energieeintrag. Für eine hohe Effizienz wird bei jeder Spannung ein geringer Eigenleistungsverbrauch gefordert. Im Ergebnis wird ein Konzept vorgestellt, welches einen zuverlässigen wartungsfreien Betrieb ermöglicht. Funktionen, wie die Abschaltung des Mikrocontrollers nach Erledigung der Aufgabe, ermöglichen darüber hinaus, weniger Energie als im Schlafmodus zu verbrauchen. Mit dieser Methode kann ein intermittierender Betrieb in Abhängigkeit der verfügbaren Energie realisiert werden. Simulation, experimentelle Untersuchung und die Einbettung in einen umgebungsversorgten drahtlosen Sensorknoten validieren die Funktionsfähigkeit unter allen gestellten Anforderungen. Der mittlere Eigenleistungsverbrauch der vorgeschlagenen Schaltung liegt bei 5,58 µW. Bei niedrigen Spannungen von 0 V – 1,4 V werden lediglich 568 nW benötigt. / The use of ambient energy enables an autonomous energy supply for an increasing number of wireless sensor node applications. Maintenance interventions or unforeseen energy input drops limit the autonomous use of such sensor nodes or require significantly oversized energy harvesters and energy storages. Applications such as the use in inaccessible areas, sensor networks with a large number of nodes or very small nodes / Smart Dust can become uneconomical, if no maintenance-free operation can be guaranteed. If a wireless sensor node reaches an energetically low state, it is necessary for a restart, that sufficient voltage and in addition sufficient energy is available for the starting process. In the case of too early activation, the starting process will not be completed due to the voltage drop and will prevent the start of operation. A Voltage Supervisor is required to delay the start until sufficient energy is available. Within the scope of this thesis, a voltage supervisor for the energy management of environmental-powered wireless sensor nodes is proposed. The challenges are in the realization of a defined switch-off and start characteristic even with slow or variable voltage slopes, a cold start capability and in reliable behaviour under adverse environmental conditions or low energy input. For high efficiency, a low power consumption is required at every voltage. As result, a concept is presented which enables reliable maintenance-free operation. In addition, the microcontroller can switch itself off completely after completion of the task and thus consume even less energy than in sleep mode. With this method, intermittent operation depending on the available energy, can be realized as well. Simulation, experimental investigation and inclusion in an energy harvesting supplied wireless sensor node validate the functionality under all given conditions. The average power consumption of the proposed circuit is 5.58 µW. At low voltages in the range 0 V - 1.4 V only 568 nW are required.

For the transport of their spacecraft from the vehicle assembly building to the launch pads at Kennedy Space Centre, Florida, the National Aeronautics and Space Administration (NASA) is using two special crawler transporters since 1965. First developed for the Saturn V rocket the crawler transporters have been sufficient for all following generations of space ships so far. But for the new generation of Orionspacecraft which is under development now, a load capacity increase for the crawler transporter of plus 50% was necessary. For this task Hunger Hydraulik did develop new jacking, equalizing and levelling (JEL) cylinders with sufficient load capacity but also with some new features to improve the availability, reliability and safety of this system. After design approval and manufacture of the cylinders they have been tested in a special developed one-to-one scale dynamic test rig and after passing this the cylinders had to prove their performance in the crawler transporter itself. This article describes the general application and introduces the technical requirements of this project as well as the realized solution.