This thesis describes optimisation and characterisation of confocal Raman microspectrometer in the laboratory, and its application on several materials of technological importance. Optimisation in scanning improved the repeatability of scanning from –lOum to –2um. The lateral and depth resolutions of the optimised system were approximately 1um and 5um respectively. The depth resolution of the current system was approximately 40% worse than in commercial instruments. A theoretical model has been proposed to describe the confocal operation of the optical system. To the best of the author’s knowledge, the model has not been published elsewhere. The model was found useful in determining optimum combination of pinhole size and auxiliary lens in the confocal Raman system. For the first time, the optimised confocal Raman microspectrometer was used to study polymethylmethacrylate/polystyrene(PMMA/PS) copolymer film. It was found that PMMA component exists in the form of spheres of various sizes on PS matrix layer, and this is first direct confirmation of results of previous studies that investigated fluorophore-labelled PMMA/PS copolymer. Studies on annealed proton-exchanged lithium niobate(APE LN) revealed that there is a correlation between refractive index profiles and intensity ratios of low-frequency Raman peaks, but the exact nature of the relationship could not be determined due to time limitation. Nevertheless, the study showed that changes in intensity ratios of the low-frequency Raman peaks could be used to describe the refractive index profiles.

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This thesis is looking into the dependability of a Electrocardiogram(ECG) based Healthcare Body Sensor Network system (HC-BSNs). For these type of devices, the dependability is not only depending on the devices themselves, but also heavily depending on how the devices are used. Existing literature has identified that there are around 4% of usage issues when existing ECG devices are used by professionals. The rate of usage issue will not be better for the ECG-Based HC-BSNs as these devices are more likely to be used by untrained people. Subsequently, it is with paramount importance to address the usage issues so that the overall dependability of the ECG-Based HC-BSNs can be assured. Our approach to address the usage issue is to detect the usage-related anomaly, which is contained in the captured signal when erroneous usage is made, and identify the cause to the usage-related anomaly automatically and without human intervention. By doing this, the user can be prompted with clearer and accurate correction instruction. Subsequently, the usage issues can be well corrected by the user. Based on the above concept, in this thesis, we have studied the anomalous signals which can be caused by the usage issues. Two methodologies, names as AID and FFNAID, have been proposed and evaluated to detect the usage-related anomalies. We have also studied how each usage issue can affect the signals on a mote, and we use the knowledge learnt from the study to propose a methodology, named as ACLP, to identify the root cause to the usage-related anomaly. All these methodologies are fully automated and does not require any human intervention once they are deployed. The evaluations have also shown the effectiveness of these methodologies.

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The thesis is presented in four main parts: (1) the design and development of a hydraulic circular weft knitting machine; (2) the construction and testing of a hydraulic lockstitch sewing machine; (3) a detailed design study and analysis of pulse-generating rotary valves; (4) the design of a multi-feeder hydraulic circular weft knitting machine. Part 1 deals with the knitting machine aspect of the project consisting of verifying that a multi-actuator rotary valve system would operate with the desired time displacement profile, and in the correct sequence. This was then used as the basis for developing a ninety-six-needle, single feeder hydraulic circular weft knitting machine. This prototype machine was tested to obtain an assessment as to the advantages offered by hydraulic knitting techniques. Part 2 involved replacing the needle and thread take-up mechanisms of a lockstitch sewing machine, by two miniature hydraulic actuators, controlled by a rotary valve. The purpose of this machine was to prove that stitches could be formed successfully, thus demonstrating any beneficial features offered by hydraulic sewing devices. Part 3 deals with the detailed design study for pulse-generating rotary valves resulting from the previous applications. This valve was a new concept in valve technology and having established its definite potential, warranted the formation of a design procedure. The study outlines a method of optimising the torque required to rotate the bobbin by the construction of a mathematical model. Part 4 was concerned with designing a multi-feeder hydraulic circular weft knitting machine. This machine, controlled by an integrated actuator rotary collar valve to generate pulses, demonstrated how a series of twelve knitting time-displacement profiles could be created by ninety-six actuators positioned in a circular configuration. Thus, the research programme has been aimed at demonstrating how high speed motions, normally obtained by mechanical devices (cams, linkages) can be produced by miniature hydraulic actuation techniques. The feasibility of using these techniques has been verified by the building and testing of probably the first ever hydraulic knitting and sewing machines.

Gas sensitive metal oxide semiconductor capacitors, utilising silicon carbide have been demonstrated for a range of applications, particularly in exhaust and combustion monitoring. As part of the control system, sensors play a pivotal role in the closed loop control of flue gas cleaning processes in power plants. Silicon Carbide Metal Oxide Semiconductor (SiC-MOS) gas sensors have previously demonstrated a response to a range of gas species including; H:, O2 and H2S. Because of the sensing mechanism responsible for the response of these sensors, these structures often limited to applications of sensing in a single gas ambient. For multiple gas species present in a mixture, it is not possible to uniquely identify the contribution from each individual gas species and so an array of sensors is required. This thesis concerns the fabrication of monolithic gas sensors and characterisation at harsh environments.

Wireless Sensor Networks (WSNs) are used for critical applications such as health care, traffic management or plant automation. Thus, we depend on their availability, and reliable, resilient and accurate operation. It is therefore essential that these systems are protected against attackers who may intend to interfere with operations. Existing security mechanisms cannot always be directly transferred to the application domain of WSNs, and in some cases even novel methods are desirable to give increased protection to these systems. The aim of the work presented in this thesis is to augment security of WSNs by devising novel mechanisms and protocols. In particular, it contributes to areas which require protection mechanisms but have not yet received much attention from the research community. For example, the work addresses the issue of secure storage of data on sensor nodes using cryptographic methods. Although cryptography is needed for basic protection, it cannot always secure the sensor nodes as the keys might be compromised and key management becomes more challenging as the number of deployed sensor nodes increases. Therefore, the work includes mechanisms for node identification and tamper detection by means other than pure cryptography. The three core contributions of this thesis are (i) Methods for confidential data storage on WSN nodes. In particular, fast and energy-efficient data storage and retrieval while maintaining the required protection level is addressed. A framework is presented that provides confidential data storage in WSNs with minimal impact on sensor node operation and performance. This framework is further advanced by combining it with secure communication in WSNs. With this framework, data is stored securely on the flash file system such that it can be directly used for secure transmission, which removes the duplication of security operations on the sensor node. (ii) Methods for node identification based on clock skew. Here, unique clock drift patterns of nodes, which are normally a problem for wireless network operation, are used for non-cryptographic node identification. Clock skew has been previously used for device identification, requiring timestamps to be distributed over the network, but this is impractical in duty-cycled WSNs. To overcome this problem, clock skew is measured locally on the node using precise local clocks. (iii) Methods for tamper detection and node identification based on Channel State Information (CSI). Characteristics of a wireless channel at the receiver are analysed using the CSI of incoming packets to identify the transmitter and to detect tampering on it. If an attacker tampers with the transmitter, it will have an effect on the CSI measured at the receiver. However, tamper-unrelated events, such as walking in the communication environment, also affect CSI values and cause false alarms. This thesis demonstrates that false alarms can be eliminated by analysing the CSI value of a transmitted packet at multiple receivers.

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