A Novel Physical Layer Secure Key Generation and Refreshment Scheme for Wireless Sensor Networks

Physical Layer Secure Key Generation (PL-SKG) schemes have received a lot of attention from the wireless security community in recent years because of the potential benefits that they could bring to the security landscape. These schemes aim to strengthen current security protocols by reducing the amount of key material that devices need for deployment. They do this by harnessing the common source of randomness provided by the wireless channel that the physical layer is communicating over. This is of particular importance in Wireless Sensor Networks (WSNs) where resources are particularly scarce and where issues such as key revocation and recovery make the design of efficient key management schemes extremely difficult. This paper discusses the issues and challenges encountered in the design and implementation of PL-SKG schemes on off-the-shelf wireless sensor networks. It then proposes a novel key generation scheme that takes advantage of both the power and simplicity of classic error correcting codes and also the diversity of frequency channels available on 802.15.4 compliant nodes to generate keys from received signal strength (RSS) readings. This paper shows that our key generation and refreshment scheme can achieve a near 100% key reconciliation rate whilst also providing perfect forward and backward security

A Survey on Lightweight Entity Authentication with Strong PUFs

Physically unclonable functions (PUFs) exploit the unavoidable manufacturing variations of an integrated circuit (IC). Their input-output behavior serves as a unique IC \u27fingerprint\u27. Therefore, they have been envisioned as an IC authentication mechanism, in particular the subclass of so-called strong PUFs. The protocol proposals are typically accompanied with two PUF promises: lightweight and an increased resistance against physical attacks. In this work, we review nineteen proposals in chronological order: from the original strong PUF proposal (2001) to the more complicated noise bifurcation and system of PUFs proposals (2014). The assessment is aided by a unied notation and a transparent framework of PUF protocol requirements

Modelling, simulation and real time implementation of a three phase AC to AC matrix converter

Matrix converters (MCs) are essentially forced commutated cycloconverters with inherent four quadrant operation consisting of a matrix of bidirectional switches such that there is a switch for each possible connection between the input and output lines. Matrix converter directly converts the AC input voltage at any given frequency to AC output voltage with arbitrary amplitude at any unrestricted frequency without the need for a dc link capacitor storage element at the input side.The introduction of bidirectional switches using power transistors and IGBTs made easy realization of the matrix converter. The real development of the matrix converter starts with the work of Venturini and Alesina who proposed a mathematical analysis and introduced the Low-Frequency Modulation Matrix concept to describe the low frequency behavior of the matrix converter [1-3]. In this, the output voltages are obtained by multiplication of the modulation matrix or transfer matrix with the input voltages. One of the essential requirements for switching three phase AC to three phase AC MC is that two or more bidirectional switches connected to any one output phase should NOT be closed simultaneously, as this will cause dangerously high short circuit current. Similarly any one bidirectional switch connected to each output phase should remain closed to provide a current path with inductive load.This thesis mainly provides an account of the three phase AC to three phase AC MC modelling concept with SIMULINK software using fundamental Venturini and Optimum Venturini modulation algorithm [1-8], advanced modulation algorithm such as that proposed by Sunter-Clare [11-12] and by Ned Mohan [13-14, 16-17], application of these algorithms for the Vector control of three phase Induction Motor (IM) drive [15], real time hardware in the loop simulation [51,54-55] for a three phase AC to single phase AC MC, three phase AC to three phase AC Multilevel MC (MMC) with three [18-19] and six flying capacitors per output phase using PSCAD software (as SIMULINK started shooting trouble), Indirect (ISVM) [25-30] and Direct (DASVM, DSSVM, CZASVM) [31-38] Space Vector Modulation, newly discovered dual programmable AC to DC rectifier concept using three phase AC to three phase AC MC [43-45], Delta-Sigma Modulated MC [46-49] and single phase AC to three phase AC MC [50].In addition a novel concept of a single phase / three phase AC to single phase / three phase AC converter using a DC link, complementary N and P MOSFETs and IGBTs is presented. A chapter on model verification is also presented where selected SIMULINK models from various chapters have been verified by using either PSCAD or PSIM software. An appendix on PIC microcontroller PIC16F84A application to saw-tooth carrier waveform generation and switching three phase AC to three phase AC converters using a DC link is added. Another appendix on speed control and brake by plugging of three phase induction motor fed by matrix converter is presented. List of publications from this thesis is presented on third appendix

Some aspects of a code division multiple access local area network

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Interactions between innate immune effectors and multidrug resistant bacteria

Antibiotic resistance is an increasingly difficult problem in the clinic, where conventional antibiotics are failing, and new alternative solutions are in high demand. Infections caused by Gram-negative bacteria with multi drug resistance (MDR) mechanisms are increasing globally, and treatment options are limited. Plasmids encoding β-lactamases spread easily between bacteria, and the overuse of antibiotics select for MDR strains. β-lactamases are either serine- β-lactamases that are inhibited by certain β-lactamase inhibitors, and metallo-β-lactamases (MBLs), which are more difficult to inhibit with drugs. The current approach to fight MDR pathogens has mainly focused on finding β-lactamase inhibitors to use in combination with conventional antibiotics in the clinic. The overall aim of this thesis was to study the role of the cellular micro-environment and the importance of the innate immune system for antibiotic resistant bacterial infections. In Paper I we hypothesized that human cells secreted factors that could impair β-lactamase function and thus restore antibiotic susceptibility in resistant bacterial isolates. We found that thiols produced by the cells acted as zinc chelators that inhibited the degradation of cephalosporin antibiotics in VIM-1 producing K. pneumoniae. Notably, free thiols in urine samples had the same effect, suggesting that the environment at the site of infection can be highly important for antibiotic susceptibility and possibly also for the effect of antibiotic treatment in a clinical situation. In Paper II, we hypothesized that induction of innate effector molecules would reduce intracellular growth of MDR K. pneumoniae and exert synergistic effects with conventional antibiotics. We tested this by infecting human macrophages with MDR K. pneumoniae. Notably, induction of innate immunity in these cells resulted in improved intracellular killing of MDR K. pneumoniae. The inducers were combined with traditional antibiotics, which resulted in an additive killing effect. The data suggests that inducing innate immune effectors can be an effective alternative or addition to conventional treatments in infections caused by MDR K. pneumoniae. Finally, in Paper III, we tested the hypothesis that ESBL E. coli would be more susceptible to innate effectors compared to non-ESBL isolates. The ESBL producing isolates had lower survival in serum and whole blood than non-ESBL isolates, suggesting a biological cost for resistant isolates. In vivo studies with zebrafish embryos showed that the non-ESBL isolates killed the embryos more efficiently than ESBL isolates. The biological cost was not related to the ESBL plasmid per se as shown by experiments where the ESBL plasmid was transferred from a clinical isolate to a neutral background in non-resistant E. coli. Together, this thesis has highlighted the importance of considering the micro-environment at the site of infection, which may determine the effect of antibiotics. Next, I have shown that induction of innate immune effectors could be an alternative or additive treatment option for infections caused by MDR K. pneumoniae. Finally, I present data showing that ESBL E. coli are more susceptible to innate effectors than non-ESBL E. coli

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

IAIMS newsletter

NewsletterThe IAIMS Newsletter (1996-2005) provides valuable information about library activities and resources as well as informative articles related to information technology

Vibration of structures with non-linear damping

The work reported here is directed towards the problem of measuring and modeling non-linear damping in steel space frame civil engineering structures. In order to gain a better understanding of the damping mechanism in such structures, tests were performed on a full scale bolted lattice structure and the results of section A show that the joint' damping can be represented approximately in the form: FD =C (1 +e IXIn) where n=1. Other situations. where this form of non-linear damping occurs is in the case of fluid flow past a solid body. In offshore structures the hydro-dynamic force due to drag effects are found to be proportional to velocity squared. For non linear material damping, n, takes a value of 6. In section B. various methods of solution to the non-linear dynamical system under random excitation were studied and it was found that the 'Equivalent Non- Linear Differential Equationl, (ENL) method yields a better measure of the response of the non-linear system to white noise excitation than other approximate methods. Analytical expressions are derived for the mean-square response, probability density function and level crossing rates. With the modified IENLI method (MENL) it is shown how one can extract the non-linear damping and excitation power spectral density. A good correlation is obtained between experimental and theoretical results

The spectroscopy of bound and predissociating Rydberg states of NO in external electric fields

This thesis reports the application of static and ramped electric fields to the Rydberg states of NO. Chapter 1 introduces the history of Rydberg states, their exotic properties, decay mechanisms, and the effect of an applied electric field. Chapter 2 details the experimental set-up used for the experiments presented in this thesis. Chapter 3 describes the structure of NO and multiphoton excitation scheme utilised for the work presented in this thesis. Chapter 4 investigates the effect of applied DC electric fields in the range 0 – 150 V cm-1 on the predissociating Rydberg states of NO below the υ+ = 0 ionisation limit, with principal quantum numbers n = 25 – 30. The Stark states are accessed by two-colour, double-resonance excitation via the υ′ = 0,N′ = 0, 1, 2, and 4 rovibrational states of the A2Σ+ state. The N (2D) atoms produced by predissociation are measured by (2 + 1) resonance-enhanced multiphoton ionization. The zero field and predissociation spectra are analysed using a matrix diagonalisation method. In Chapter 5, initial progress on simulating the spectra is presented. The predissociation spectra are compared with pulsed-field ionization spectra of the bound Rydberg state population providing an almost complete picture of the Rydberg state dynamics. In Chapter 6, ramped fields of varying slew rates are applied to the bound Rydberg states of NO, and the ionisation time profiles are obtained. The development of the experimental chamber and investigation into sources of electrical noise required to achieve this is discussed. It is shown that the rotational quantum state composition of field-ionised molecules can be controlled by varying the slew rate of the applied electric field