Manufacturing companies need to be able to respond to customer demand quickly and accurately. This requires the capability to manage product data effectively. Product Data Management (PDM) systems have been identified as a solution to deliver this capability by providing the right information to the right people at the right time and in the right format. The foundation of this research is that the concept of PDM is relevant and important within the product development process. This research focuses upon how the PDM concept is applied in practice to define and configure products and how it can be integrated with other major information systems to enable an enterprise wide information system. To enable the research aim, an extensive review of literature was undertaken to investigate the effectiveness of PDM in enhancing the product definition process and in creating an interface between different business functional areas. A survey ofPDM system usage was undertaken aimed at identifying the current level of PDM usage within manufacturing enterprises in the UK. This was followed up by three industrial case studies to provide some degrees of validation of the results obtained. A need for effective one time order capture was identified from the three case studies which led to the development of a model specification for a late product configuration tool. A prototype system was produced to validate the design specification and was successfully demonstrated to a collaborating company. During the submission of this thesis, the collaborating company and the university are working on funding a project to pursue with its implementation. The work undertaken has firmly established the relevance ofPDM within the product development process and the importance of effective interfaces between PDM and other manufacturing information systems. The research will be of interest to small and medium sized manufacturing companies searching solutions for improving the management of their product data to enhance product definition and configuration.

The rapid and significant development of communications links between satellites has made it possible to use various applications such as relay voice, video, multimedia, etc. As a result, a great deal of research has been done in this field during the last few years to reduce power consumption and increase transmission reliability. This thesis is concerned with an analysis of intersatellite links in free space, with optical links using laser sources being considered in particular. It includes a literature survey and a thorough theoretical investigation into designing the model of the link in free space. This thesis describes the novel technique of designing the optical receiver that consists of PIN photodiode as a photodetector, Semiconductor optical amplifier (SOA) and a 3rd order Butterworth filter with central decision detection. In addition, it discusses the use of several different coding schemes for use in such links: multiple pulse position modulation (MPPM); digital pulse position modulation (DPPM); Dicode pulse position modulation (Dicode PPM). This novel technique of an optical receiver is investigated and new work is presented in order to examine the noise performance of this optical receiver and hence determine its sensitivity and the number of photons received for a specified error rate. Further new work is carried out to compare these coding schemes in terms of error weightings and coding efficiency through showing how the PCM error rate is affected by false alarm and erasure errors for MPPM, DPPM and Dicode PPM coding 3, 4, 5 and 6 bits of PCM. An original maximum likelihood sequence detector (MLSD) is presented in this thesis in order to perform these comparisons. In addition, computer simulations models (using MCAD) are performed to compare these three coding schemes operating with 3, 4, 5 and 6 bits of PCM in terms of sensitivity and bandwidth efficiency. These comparisons show that MPPM coding 3, 4, 5 and 6 bits of PCM is the appropriate coding scheme to be used in optical inter-satellite links in free space and PCM data rates of 1 Gbit/s.

Traditional scheduling techniques are of a by-gone era and do not cater for the dynamism of new and emerging computing paradigms. Budget constraints now push researchers to migrate their workloads to public clouds or to buy into shared computing services as funding for large capital expenditures are few and far between. The sites still hosting large or shared computing infrastructure have to ensure that the system utilisation and efficiency is as high as ossible. However, the efficiency can not come at the cost of quality of service as the availability of public clouds now means that users can move away. This thesis presents a novel scheduling system to improve job turn-around-time. The Robust Mouldable Scheduler outlined in these pages utilises real application benchmarks to profile system performance and predict job execution times at different allocations, something no other scheduler does at present. The system is able to make an allocation decisions ensuring the jobs can fit into spaces available on the system using fewer resources without delaying the job completion time. The results demonstrate significant improvement in workload turn-around-times using real High Performance Computing (HPC) trace logs. Utilising three years of the University of Huddersfield trace logs the mouldable scheduler consistently simulated faster workload completion. Further, the results establish that by not relying on the user to suggest resource allocations for jobs the system is able to mitigate bad-put into the system leading to improved efficiency. A thorough investigation of Research Computing Systems (RCS), workload management systems, scheduling algorithms and strategies, benchmarking and profiling toolkits, and simulators is presented to establish the state of the art. Within this thesis a method to profile applications and workloads that leverages common open-source tools on HPC systems is presented. The resultant toolkit is used to profile the University of Huddersfield workload. This workload forms the basis to evaluate the mouldable scheduler. The research includes advance computing paradigms such as utilising Artificial Intelligence methods to improve the efficiency of the scheduler, or Surge Computing, where workloads are scaled beyond institutional firewalls through elastic compute systems.

The area of Content-Based Image Retrieval (CBIR) deals with a wide range of research disciplines. Being closely related to text retrieval and pattern recognition, the probably most serious issue to be solved is the so-called \semantic gap". Except for very restricted use-cases, machines are not able to recognize the semantic content of digital images as well as humans. This thesis identifies the requirements for a crucial part of CBIR user interfaces, a multimedia-enabled query language. Such a language must be able to capture the user's intentions and translate them into a machine-understandable format. An approach to tackle this translation problem is to express high-level semantics by merging low-level image features. Two related methods are improved for either fast (retrieval) or accurate(categorization) merging. A query language has previously been developed by the author of this thesis. It allows the formation of nested Boolean queries. Each query term may be text- or content-based and the system merges them into a single result set. The language is extensible by arbitrary new feature vector plug-ins and thus use-case independent. This query language should be capable of mapping semantics to features by applying machine learning techniques; this capability is explored. A supervised learning algorithm based on decision trees is used to build category descriptors from a training set. Each resulting \query descriptor" is a feature-based description of a concept which is comprehensible and modifiable. These descriptors could be used as a normal query and return a result set with a high CBIR based precision/recall of the desired category. Additionally, a method for normalizing the similarity profiles of feature vectors has been developed which is essential to perform categorization tasks. To prove the capabilities of such queries, the outcome of a semi-supervised training session with \leave-one-object-out" cross validation is compared to a reference system. Recent work indicates that the discriminative power of the query-based descriptors is similar and is likely to be improved further by implementing more recent feature vectors.

This Thesis examines the role and limitations of voice biometrics in the contexts of security and for crime reduction. The main thrust of the Thesis is that despite the technical and non-technical hurdles that this research has identified and sought to overcome, voice can be an effective and sustainable biometric if used in the manner proposed here. It is contended that focused and continuous evaluation of the strength of systems within a solid framework is essential to the development and application of voice biometrics and that special attention needs to be paid to human dimensions in system design and prior to deployment. Through an interdisciplinary approach towards the theme reflected in the title several scenarios are presented of the use of voice in security / crime reduction, crime investigation, forensics and surveillance contexts together with issues surrounding their development and implementation. With a greater emphasis on security-oriented voice verification (due to the diversity of the usage scenarios and prospect of use) a new framework is presented for analysis of the reliability and security of voice verification. This research calls not only for a standard evaluation scheme and analytical framework but also takes active steps to evaluate the prototype system within the framework under various conditions. Spoof attacks, noises, coding, distance and channel effects are among the factors that are studied. Moreover, an additional under-researched area, the detection of counterfeit signals, is also explored. While numerous technical and design contributions made in this project are summarised in chapter 2, the research mainly aims to provide solid answers to the high-level strategic questions. The Thesis culminates in a synthesis chapter in which realistic expectations, design requirements and technical limitations of the use of voice for criminological and security applications are outlined and areas for further research are defined.

Emerging web services technology has introduced the concept of autonomic interoperability and portability between services. The number of online services has increased dramatically with many duplicating similar functionality and results. Composing online services to solve user needs is a growing area of research. This entails designing systems which can discover participating services and integrate these according to the end user requirements. This thesis proposes a Dynamic Web Services Composition (DWSC) process that is based upon consideration of previously successful attempts in this area, in particular utilizing AI-planning based solutions. It proposes a unique approach for service selection and dynamic web service composition by exploring the possibility of semantic web usability and its limitations. It also proposes a design architecture called Optimal Synthesis Plan Generation framework (OSPG), which supports the composition process through the evaluation of all available solutions (including all participating single and composite services). OSPG is designed to take into account user preferences, which supports optimality and robustness of the output plan. The implementation of OSPG will be con�gured and tested via division of search criteria in di�erent modes thereby locating the best plan for the user. The services composition and discovery-based model is evaluated via considering a range of criteria, such as scope, correctness, scalability and versatility metrics.

Optical fibre systems have played a key role in making possible the extraordinary growth in world-wide communications that has occurred in the last 25 years, and are vital in enabling the proliferating use of the Internet. Its high bandwidth capabilities, low attenuation characteristics, low cost, and immunity from the many disturbances that can afflict electrical wires and wireless communication links make it ideal for gigabit transmission and a major building block in the telecommunication infrastructure. A number of different techniques are used for the transmission of digital information between the transmitter and receiver sides in optical fibre system. One type of coding scheme is Pulse Position Modulation (PPM) in which the location of one pulse during 2M time slots is used to convey digital information from M bits. Although all the studies refer to advantages of PPM, it comes at a cost of large bandwidth and a complicated implementation. Therefore, variant PPM schemes have been proposed to transmit the data such as: Multiple Pulse Position Modulation (MPPM), Differential Pulse Position Modulation (DPPM), Pulse Interval Modulation (PIM), Digital Pulse Interval Modulation (DPIM), Dual Header Pulse Interval Modulation (DH-PIM), Dicode Pulse Position Modulation (DiPPM). The DiPPM scheme has been considered as a solution for the bandwidth consumption issue that other existing PPM formats suffer from. This is because it has a line rate that is twice that of the original data rate. DiPPM can be efficiently implemented as it employs two slots to transmit one bit of pulse code modulation (PCM). A PCM conversion from logic zero to logic one provides a pulse in slot RESET (R) and from one to zero provides a pulse in slot SET (S). No pulse is transmitted if the PCM data is unvarying. Like other PPM schemes, DiPPM suffers from three types of pulse detection errors wrong slot, false alarm, and erasure. The aim of this work was to build an error correction system, Reed Solomon (RS) code, which would overcome or reduce the error sources in the DiPPM system. An original mathematical program was developed using the Mathcad software to find the optimum RS parameters which can improve the DiPPM system error performance, number of photons and transmission efficiency. The results showed that the DiPPM system employing RS code offered an improvement over uncoded DiPPM of 5.12 dB, when RS operating at the optimum code rate of approximately ¾ and a codeword length of 25 symbols. Moreover, the error performance of the uncoded DiPPM is compared with the DiPPM system employing maximum likelihood sequence detector (MLSD), and RS code in terms of number of photons per pulse, transmission efficiency, and bandwidth expansion. The DiPPM with RS code offers superior performance compared to the uncoded DiPPM and DiPPM using MLSD, requiring only 4.5x103 photons per pulse when operating at a bandwidth equal to or above 0.9 times the original data rate. Further investigation took place on the DiPPM system employing RS code. A Matlab program and very high speed circuit Hardware Description language (VHDL) were developed to simulate the designed communication system. Simulation results were considered and agreed with the previous DiPPM theory. For the first time, this thesis presents the practical implementation for the DiPPM system employing RS code using Field Programmable Gate Array (FPGA).

Low Cr alloys are mostly utilized in structural components such as steam pipes, turbine generators and reactor pumps operating at high temperatures from 400℃ to 700℃ in nuclear power plants. For safe operation, it is necessary at the design stage to predict and understand the creep damage behaviour of low Cr alloys under long-term service conditions but under low stress levels. Laboratory creep tests can be utilized in the investigation of creep damage behaviour, however, these are usually expensive and time-consuming. Thus, constitutive modelling is considered here for both time and economic efficiency. Existing constitutive equations for describing creep are mostly proposed based on experimental data for materials under high stresses. For low stress levels, the computational determination of a current state is extrapolated from those constitutive equations by simply using a powerlaw or sinh law. However, experimental observation has shown that this method is not satisfactory. The aim of the current research is to utilize continuum damage mechanics (CDM) to improve the constitutive equations for low Cr alloys under long-term service. This project provides three main contributions. The first is a more accurate depiction of the relationship between minimum creep rate and stress levels. The predicted creep rates show good agreement with creep data observed experimentally for both 2.25Cr-1Mo steel and 0.5Cr-0.5Mo- 0.25V steel creep specimens. Secondly, it gives a more comprehensive description of the relationship between creep damage and creep cavitation. The CDM approach has been used and a reasonable agreement has also been achieved between predicted creep strain and experimental data for 0.5Cr-0.5Mo-0.25V base material under the critical stress of 40MPa at 640℃. Thirdly, it proposes a more accurate creep rupture criterion in the creep damage analysis of low Cr alloys under different stress levels. Based on investigation of creep cavitation for 2.25Cr-1Mo steel, the area fraction of cavitation at rupture time obviously differs under different stress levels. This thesis contributes to computational creep damage mechanics in general and in particular to the design of a constitutive model for creep damage analysis of low Cr alloys. The proposed constitutive equations are only valid at low and intermediate stress levels. Further work needs to be undertaken when more experimental data are available.

Current trends in technology are leading to a need for ever smaller and more complex featured surfaces. The techniques for manufacturing these surfaces are varied but are tied together by one limitation; the lack of useable, on-line metrology instrumentation. Current metrology methods require the removal of a workpiece for characterisation which leads to machining down-time, more intensive labour and generally presents a bottle neck for throughput. In order to establish a new method for on-line metrology at the nanoscale investigation are made into the use of optical fibre interferometry to realise a compact probe that is robust to environmental disturbance. Wavelength tuning is combined with a dispersive element to provide a moveable optical stylus that sweeps the surface. The phase variation caused by the surface topography is then analysed using phase shifting interferometry. A second interferometer is wavelength multiplexed into the optical circuit in order to track the inherent instability of the optical fibre. This is then countered using a closed loop control to servo the path lengths mechanically which additionally counters external vibration on the measurand. The overall stability is found to be limited by polarisation state evolution however. A second method is then investigated and a rapid phase shifting technique is employed in conjunction with an electro-optic phase modulator to overcome the polarisation state evolution. Closed loop servo control is realised with no mechanical movement and a step height artefact is measured. The measurement result shows good correlation with a measurement taken with a commercial white light interferometer.

Motor current signature analysis (MCSA) has been an effective method to monitor electrical machines for many years, predominantly because of its low instrumentation cost, remote implementation and comprehensive information contents. However, it has shortages of low accuracy and efficiency in resolving weak signals from incipient faults, such as detecting early stages of induction motor fault. In this thesis MCSA has been improved to accurately detect electrical and mechanical faults in the induction motor namely broken rotor bars, stator faults and motor bearing faults. Motor current signals corresponding to a healthy (baseline) and faulty condition on induction motor at different loads (zero, 25%, 50% and 75% of full load) were rearranged and the baseline current data were examined using conventional methods in frequency domain and referenced for comparison with new modulation signal bispectrum. Based on the fundamental modulation effect of the weak fault signatures, a new method based on modulation signal bispectrum (MSB) analysis is introduced to characterise the modulation and hence for accurate quantification of the signatures. This method is named as (MSB-SE). For broken rotor bar(BRB), the results show that MSB-SE suggested in this research outperforms conventional bispectrum CB significantly for all cases due its high performance of nonlinear modulation detection and random noise suppression, which demonstrates that MSB-SE is an outstanding technique whereas (CB) is inefficient for motor current signal analysis [1] . Moreover the new estimators produce more accurate results at zero, 25%, 50%, 75% of full load and under broken rotor bar, compared with power spectrum analysis. Especially it can easily separate the half BRB at a load as low as 25% from baseline where PS would not produce a correct separation. In case of stator faults, a MSB-SE is investigated to detect different severities of stator faults for both open and short circuit. It shows that MSB-SE has the capability to accurately estimate modulation degrees and suppress the random and non-modulation components. Test results show that MSB-SE has a better performance in differentiating spectrum amplitudes due to stator faults and hence produces better diagnosis performance, compared with that of power spectrum (PS). For motor bearing faults, tests were performed with three bearing conditions: baseline, outer race fault and inner race fault. Because the signals associated with faults produce small modulations to supply component and high noise levels, MSB-SE is used to detect and diagnose different motor bearing defects. The results show that bearing faults can induce detectable amplitude increases at its characteristic frequencies. MSB-SE peaks show a clear difference at these frequencies whereas the conventional power spectrum provides change evidences only at some of the frequencies. This shows that MSB has a better and reliable performance in detecting small changes from the faulty bearing for fault detection and diagnosis. In addition, the study also shows that current signals from motors with variable frequency drive controller have too much noise and it is unlikely to discriminate the small bearing fault component. This research also applies a mathematical model for the simulation of current signals under healthy and broken bars condition in order to further understand the characteristics of fault signature to ensure the methodologies used and accuracy achieved in the detection and diagnosis results. The results show that the frequency spectrum of current signal outputs from the model take the expected form with peaks at the sideband frequency and associated harmonics.