Towards Scalable Network Traffic Measurement With Sketches

Driven by the ever-increasing data volume through the Internet, the per-port speed of network devices reached 400 Gbps, and high-end switches are capable of processing 25.6 Tbps of network traffic. To improve the efficiency and security of the network, network traffic measurement becomes more important than ever. For fast and accurate traffic measurement, managing an accurate working set of active flows (WSAF) at line rates is a key challenge. WSAF is usually located in high-speed but expensive memories, such as TCAM or SRAM, and thus their capacity is quite limited. To scale up the per-flow measurement, we pursue three thrusts. In the first thrust, we propose to use In-DRAM WSAF and put a compact data structure (i.e., sketch) called FlowRegulator before WSAF to compensate for DRAM\u27s slow access time. Per our results, FlowRegulator can substantially reduce massive influxes to WSAF without compromising measurement accuracy. In the second thrust, we integrate our sketch into a network system and propose an SDN-based WLAN monitoring and management framework called RFlow+, which can overcome the limitations of existing traffic measurement solutions (e.g., OpenFlow and sFlow), such as a limited view, incomplete flow statistics, and poor trade-off between measurement accuracy and CPU/network overheads. In the third thrust, we introduce a novel sampling scheme to deal with the poor trade-off that is provided by the standard simple random sampling (SRS). Even though SRS has been widely used in practice because of its simplicity, it provides non-uniform sampling rates for different flows, because it samples packets over an aggregated data flow. Starting with a simple idea that independent per-flow packet sampling provides the most accurate estimation of each flow, we introduce a new concept of per-flow systematic sampling, aiming to provide the same sampling rate across all flows. In addition, we provide a concrete sampling method called SketchFlow, which approximates the idea of the per-flow systematic sampling using a sketch saturation event

Functional Polymer Gels based on Oligomer Fluids

Polymergele, wie beispielsweise Hydrogele, die aus vernetzten Polymerketten und niedermolekularen Lösungsmitteln bestehen, wurden aufgrund der Ähnlichkeit ihrer mechanischen Eigenschaften mit denen von weichen biologischen Geweben weit verbreitet in biomedizinischen Anwendungen, flexibler Elektronik und weichen Maschinen verwendet. Das Design von Polymernetzwerken und sein Beitrag zu den Eigenschaften solcher Materialien wurden ausgiebig untersucht. Die infundierten Lösungsmittel, die die innere Struktur von Gelen stark beeinflussen würden, werden jedoch selten untersucht. Ziel dieser Dissertation ist es, eine Reihe von Lösungsmittelstrategien zur Herstellung funktioneller Polymergele bereitzustellen. In Kapitel 1 wird eine allgemeine Einführung in funktionelle Polymergele basierend auf verschiedenen Lösungsmitteln gegeben, die die verschiedenen Wahlmöglichkeiten von Lösungsmitteln für Polymergele und von den Lösungsmittelstrategien abgeleitete Funktionen abdeckt. Für die Auswahl der Lösungsmittel wurden die Herstellungsmethoden und die neuesten Entwicklungen der Polymergele auf Basis verschiedener Lösungsmittel zusammengefasst, darunter organische Lösungsmittel, ionische Flüssigkeiten, tiefeutektische Lösungsmittel und Polymerflüssigkeiten. Dann wurden die aus den Lösungsmittelstrategien abgeleiteten Funktionen diskutiert, darunter rutschige Oberflächen, Gefrierbeständigkeit oder thermische Stabilität, überlegene mechanische Eigenschaften und elektrische Leistung. In Kapitel 3.1 wurde ein Polymergelsystem auf Basis von Poly(ethylenglykol) (PEG) als Flüssigphase demonstriert. Der kritische Einfluss der Lösungsmittelnatur auf die mechanischen Eigenschaften und die Leistung von weichen Polymergelen wurde untersucht. Als elastisches Polymernetzwerk wurde ein physikalisch vernetztes Copolymer aus 2-Hydroxyethylmethacrylat und Acrylsäure gewählt. Verglichen mit dem entsprechenden Gel auf Hydrogel- oder Ethylenglykolbasis weist das PEGgel außergewöhnliche physikalische Eigenschaften auf, wie z. B. hohe Dehnbarkeit und Zähigkeit, schnelle Selbstheilung und Langzeitstabilität unter Umgebungsbedingungen. Je nach Molekulargewicht und PEG-Anteil variierte die Zugfestigkeit von PEGgelen von 0,22 MPa bis 41,3 MPa, die Bruchdehnung von 12 % bis 4336 %, der Elastizitätsmodul von 0,08 MPa bis 352 MPa und die Zähigkeit von 2,89 MJ m-3 bis 56,23 MJ m-3. Die erhaltenen Polymergele können zur Herstellung eines selbstheilenden pneumatischen Aktuators durch 3D-Druck verwendet werden. Die verbesserten mechanischen Eigenschaften des PEGgel-Systems könnten auf andere Polymernetzwerke (sowohl chemisch als auch physikalisch vernetzt) ausgedehnt werden. In Kapitel 3.2 wurden Ionen in das Lösungsmittelsystem eingeführt, um ionisches PEGgel herzustellen. Der Einbau von Ionen in PEG erhöht gleichzeitig die Festigkeit und Zähigkeit der Polymergele. Das typische ionische PEGgel besteht aus in situ gebildeten, physikalisch vernetzten Poly(2-hydroxyethylmethacrylat)-Netzwerken und PEG und weist eine hohe Leitfähigkeit (0,04 S m-1), eine ausgezeichnete elektrochemische Stabilität (> 60.000 Zyklen), eine extreme Dehnbarkeit ( bis zu 1400 %), hohe Zähigkeit (7,16 MJ m-3), schnelle Selbstheilungseigenschaft, die eine Wiederherstellung der Ionenleitfähigkeit innerhalb von Sekunden ermöglicht, sowie keine Lösungsmittelleckage auf. Mehrere Anwendungen von ionischem PEGgel wurden als (a) flexible Sensoren zur Dehnungs- oder Temperaturmessung, (b) Hautelektroden zur Aufzeichnung von Elektrokardiogrammen und (c) als robustes und sensorisches Material für pneumatische künstliche Muskeln demonstriert. In Kapitel 3.3 wurde eine In-situ-Phasentrennung im PEGgel-System unter Verwendung der Mischung aus PEG und Polypropylenglykol (PPG) als Lösungsmittel gebildet. Die phasengetrennten Polymergele wurden durch direktes Polymerisieren von 2-Hydroxyethylmethacrylat in einer Mischung aus PEG und PPG hergestellt. Die polymerisierten elastischen Netzwerke weisen eine unterschiedliche Löslichkeit in PEG (hochlöslich) und PPG (schwach löslich aufgrund des vorhandenen Methyls in der Hauptkette) auf, was zu einem makroskopisch homogenen kovalenten Netzwerk mit in-situ-Phasentrennung führt. Das resultierende phasengetrennte gel zeigt eine hohe Festigkeit (8,0 MPa), eine günstige Bruchdehnung (430 %) und eine große Zähigkeit (17,0 J m-3). Die getrennten Phasen verleihen dem Polymergel eine Formgedächtniseigenschaft, die für verschiedene weiche Maschinen in Kombination mit 3D-Druckfähigkeit verwendet werden kann. Dann wurden Ionen in das PEG/PPG-Lösungsmittel eingebaut, um eine hierarchische Verbesserung in Polymergelen zu erreichen, die von den ionischen Wechselwirkungen (Nanoebene) bis zur Phasentrennung (Mikroebene) reicht. Eine solche hierarchische Struktur verbesserte die Festigkeit und Zähigkeit von Polymergelen weiter und zeigte eine hohe Bruchfestigkeit (12,2 MPa) und Bruchenergie (54 kJ m-2). Abschließend wurde ein Ausblick auf die Herausforderungen gegeben, denen man sich bei der Entwicklung funktioneller Polymergele stellen muss. Um die Entwicklung von Polymergelen in verschiedenen Bereichen zu beschleunigen, müssen wir sowohl das Netzwerkdesign als auch die Lösungsmittelstrategien optimieren. Fortschritte auf nur einer Seite reichen nicht aus, um alle Herausforderungen zu lösen

Methodologies to improve product life cycle decision making in the telecommunications industry

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.As pressure from regulation and customers increases on telecommunications equipment manufacturers and service providers to reduce the hazardous material content of telecommunications products and generally improve environmental performance, new methods for Product Life Cycle Management are required. Supplier and component environmental evaluation are vital and fundamental elements of any Product Life Cycle Management programme, as is the capture of data from the supply base. The information that needs to be captured from the supply base to meet the requirements of customers of telecommunications equipment providers; to meet the requirements of legislation; and to provide data for improving ecodesign and facilitating product-focused continual improvement for ISO 14001 has been identified. A method for capturing data from the supply base has been developed and recommendations made for implementation. A hierarchical supplier and component eco-evaluation methodology has been developed and tested. This methodology incorporates supplier environmental management performance, component inherent human toxicity, ecotoxicity and resource depletion. It provides component qualifiers and purchasers with a method of supplier environmental performance comparison and enables this criterion to be integrated with existing criteria such as quality and cost in the component and supplier selection decision-making process. Recommendations are made regarding the implementation of an industry-wide system to enable the capture of detailed product material composition data from the supply chain and the implementation of the eco-evaluation methodology to identify the supplier that has superior environmental performance. The result will be enhanced decision making in product design and manufacture, improved transparency in communication to customers and more informed decision-making at the end-of-life stage of the product life cycle.Funding was obtained from the Engineering and Physical Sciences Research Council

Combinatorics-based energy conservation methods in wireless sensor networks

Ph.DDOCTOR OF PHILOSOPH

End-of-life implications of electronic textiles - Assessment of a converging technology

Contemporary innovation in the converging technology sectors of electronics and textile aims at augmenting functionality of textiles, making them “smart”. That is, integrating electronic functions such as sensing, data processing, and networking into wearable products. Embedding electronic devices into textiles results in a novel category of products: electronic textiles (e-textiles). Whereas researchers and innovators are pushing forward technological development little attention has been paid to the end-of-life implications of such future products. E-textiles may not only entail promising business opportunities but also adverse environmental impacts. This study examines potential end-of-life implications, which could emerge once future e-textiles are disposed of. Using the methodological framework of technology assessment an overview of current innovation processes for e-textiles is established and an outlook on future applications areas is provided. Further, information on technologies and materials composition of e-textiles is mapped as a basis for assessing the prospective implications at the end of their useful life. The findings suggest that widespread application of e-textiles could result in the emergence of a new waste stream. There are various parallels to electronic waste, which causes profound environmental problems nowadays. Risks include potential release of toxic substances during the disposal phase. And, loss of scarce materials is to be expected if no recycling takes place. This would accelerate the depletion of resources. Recycling of textile integrated electronic devices will be difficult. From the analysis it can be deduced that today’s schemes for takeback, recycling and disposal would not be sufficient to cope with waste e-textiles in an environmentally benign manner. Instead, discarded e-textiles would find their way into solid waste and increase the existing environmental problems of waste disposal. The study concludes with recommendations for policy makers and technology developers on how a waste preventative technology design could be achieved

A comparison of processing techniques for producing prototype injection moulding inserts.

This project involves the investigation of processing techniques for producing low-cost moulding inserts used in the particulate injection moulding (PIM) process. Prototype moulds were made from both additive and subtractive processes as well as a combination of the two. The general motivation for this was to reduce the entry cost of users when considering PIM. PIM cavity inserts were first made by conventional machining from a polymer block using the pocket NC desktop mill. PIM cavity inserts were also made by fused filament deposition modelling using the Tiertime UP plus 3D printer. The injection moulding trials manifested in surface finish and part removal defects. The feedstock was a titanium metal blend which is brittle in comparison to commodity polymers. That in combination with the mesoscale features, small cross-sections and complex geometries were considered the main problems. For both processing methods, fixes were identified and made to test the theory. These consisted of a blended approach that saw a combination of both the additive and subtractive processes being used. The parts produced from the three processing methods are investigated and their respective merits and issues are discussed

Reducing risk in pre-production investigations through undergraduate engineering projects.

This poster is the culmination of final year Bachelor of Engineering Technology (B.Eng.Tech) student projects in 2017 and 2018. The B.Eng.Tech is a level seven qualification that aligns with the Sydney accord for a three-year engineering degree and hence is internationally benchmarked. The enabling mechanism of these projects is the industry connectivity that creates real-world projects and highlights the benefits of the investigation of process at the technologist level. The methodologies we use are basic and transparent, with enough depth of technical knowledge to ensure the industry partners gain from the collaboration process. The process we use minimizes the disconnect between the student and the industry supervisor while maintaining the academic freedom of the student and the commercial sensitivities of the supervisor. The general motivation for this approach is the reduction of the entry cost of the industry to enable consideration of new technologies and thereby reducing risk to core business and shareholder profits. The poster presents several images and interpretive dialogue to explain the positive and negative aspects of the student process

Energy Management

Forecasts point to a huge increase in energy demand over the next 25 years, with a direct and immediate impact on the exhaustion of fossil fuels, the increase in pollution levels and the global warming that will have significant consequences for all sectors of society. Irrespective of the likelihood of these predictions or what researchers in different scientific disciplines may believe or publicly say about how critical the energy situation may be on a world level, it is without doubt one of the great debates that has stirred up public interest in modern times. We should probably already be thinking about the design of a worldwide strategic plan for energy management across the planet. It would include measures to raise awareness, educate the different actors involved, develop policies, provide resources, prioritise actions and establish contingency plans. This process is complex and depends on political, social, economic and technological factors that are hard to take into account simultaneously. Then, before such a plan is formulated, studies such as those described in this book can serve to illustrate what Information and Communication Technologies have to offer in this sphere and, with luck, to create a reference to encourage investigators in the pursuit of new and better solutions