An agent-based implementation of hidden Markov models for gas turbine condition monitoring

This paper considers the use of a multi-agent system (MAS) incorporating hidden Markov models (HMMs) for the condition monitoring of gas turbine (GT) engines. Hidden Markov models utilizing a Gaussian probability distribution are proposed as an anomaly detection tool for gas turbines components. The use of this technique is shown to allow the modeling of the dynamics of GTs despite a lack of high frequency data. This allows the early detection of developing faults and avoids costly outages due to asset failure. These models are implemented as part of a MAS, using a proposed extension of an established power system ontology, for fault detection of gas turbines. The multi-agent system is shown to be applicable through a case study and comparison to an existing system utilizing historic data from a combined-cycle gas turbine plant provided by an industrial partner

Application of quantitative vegetation reconstruction techniques to Late Holocene records at Inshriach Forest

This thesis considers some of the main issues surrounding the quantitative models that have been developed to reconstruct vegetation from pollen assemblages. Conducted within a pine dominated woodland, a palynologically difficult landscape, to determine vegetation changes over the late Holocene the results highlight the complexities of undertaking such studies in these contexts. Pollen productivity estimates were calculated from moss samples over the woodland using complete sets and derived subsets to detect influences of sampling design on resultant model output. Differences in the PPE sets were compared using reconstructions from simulation models in comparison to observed vegetation patterns. The results indicate that both parameter calculation and model reconstructions were influenced by the landscape form and composition. Sensitivity of the models to such small variations in parameter values heightens the need for robust data generation and increased investigation to controlling factors on pollen productivity. Performance of the reconstruction models experienced variation with respect to deposition basin size and site specific characteristics. Overall, the regional reconstructions proved to generate more confident estimates of vegetation cover whilst local scale reconstructions were subject to greater variability. Comparison of the quantitative modelling to standard interpretation and the modern analogue approach shows contrasts between the results obtained with respect to limitations associated with each method and the time frames, recent (ca. 100 years) and longer (ca. 3000 years), over which they were applied. Consequently, no one quantitative approach could be identified as being superior as site specific variations were recognised in relation to the most suitable approach. In response, a hierarchical technique is proposed to utilise the benefits of each technique and to obtain detailed information to strengthen interpretations. However, it is stressed study specific constrains that determine the available resources will influence the ability to fully apply this composite approach.NERC CASE (Forest Research

The Stereoselective synthesis of polyene natural products

A strategy for the stereocontrolled synthesis of polyene units was developed which centred around the chemistry of the vinyl boronate ester 4,4,6-trimethyl-2-vinyl-l,3,2- dioxaborinane 123. Reaction conditions have been developed to allow the Heck coupling of 123 with a range of aryl and alkenyl electrophiles. The reaction is promoted by cationic palladium species which can be generated through the addition of metal salts to the reaction mixture. Conversely conditions have also been developed which allows 123 to react exclusively at the boron functionality along the Suzuki-Miyaura pathway, the syntheses of a range of styrene and diene systems being demonstrated. Vinyl boronate 123 demonstrates complete chemoselectivity which is controlled by the reaction conditions employed. The alkenyl boronate esters, products of the Heck coupling of 123, can be converted to alkenyl iodides to produce the E- or Z-isomer with extremely high geometrical purity. This is done through an iododeboronation reaction involving ICI and NaOMe where the order of reagent addition determines the stereochemical outcome. Presented within is a detailed insight into the mechanistic intricacies of the transformations and the use of alternative and novel reagents such as pyridine-ICl for stereoselective iodo- and chlorodeboronation reactions is also demonstrated. This strategy was successfully applied to the syntheses of 1,6-diphenyl-1,3,5- . hexatrienes of varying alkene geometries 205-207, which were prepared from just iodobenzene and vinyl boronate 123 using those three key reactions. The use of this strategy also went some way to preparing the tetraene-containing natural product ixoric acid 124, although a total synthesis was not achieved during these studies. Research towards the first total synthesis of the natural product viridenomycin 125 was also conducted, especially towards the cyclopentenol core 246. An advanced intermediate cyclopentenone 248, was prepared from readily available starting materials along a succinct synthetic pathway to provide 248 in a good yield whilst expressing high diastereo- and enantioselectivity. Thus, a route was demonstrated which appears superior to those already existing in the literature

An Industrial Digitalization Platform for Condition Monitoring and Predictive Maintenance of Pumping Equipment

This paper is concerned with the implementation and field-testing of an edge device for real-time condition monitoring and fault detection for large-scale rotating equipment in the UK water industry. The edge device implements a local digital twin, processing information from low-cost transducers mounted on the equipment in real-time. Condition monitoring is achieved with sliding-mode observers employed as soft sensors to estimate critical internal pump parameters to help detect equipment wear before damage occurs. The paper describes the implementation of the edge system on a prototype microcontroller-based embedded platform, which supports the Modbus protocol; IP/GSM communication gateways provide remote connectivity to the network core, allowing further detailed analytics for predictive maintenance to take place. The paper first describes validation testing of the edge device using Hardware-In-The-Loop techniques, followed by trials on large-scale pumping equipment in the field. The paper concludes that the proposed system potentially delivers a flexible and low-cost industrial digitalization platform for condition monitoring and predictive maintenance applications in the water industry

Approaches to quantitative reconstruction of woody vegetation in managed woodlands from pollen records

There has been increasing interest in developing quantitative methods for reconstructing the dynamics of cultural landscapes over the last 15 years. This paper adds to this literature by using various approaches to reconstruct the vegetation of two woodlands subject to rotational coppicing (the periodic cutting of broadleaved trees and shrubs for wood products). Pollen deposition at ground level was determined at both sites using ‘Tauber’ traps placed near to the centre of 14 compartments of differing age in the coppice rotation. For the main woody taxa, Relative Pollen Productivity (RPP) estimates were derived using linear regression for pollen influx data and Extended R-value analysis for percentage data. The vegetation around three ponds was reconstructed by applying four methods (inverting the two RPP estimate approaches, the modern analogue technique and correction for pollen productivity using the linear regression estimated RPP values) to pollen data obtained from the uppermost sample of sediment from the ponds. To determine whether these methods gave better estimates of the vegetation composition than the original pollen proportions, the results were compared with the surveyed vegetation around each pond using the Bray–Curtis Index. Linear regression of pollen influx produced RPP values which are comparable with previous European studies, whilst for some taxa the Extended R-value analysis produced estimates which are orders of magnitude different both from values derived from the linear regression and previous work. No single approach performed equally well at reconstructing the vegetation around the ponds, and at two of the three locations the uncorrected pollen proportions were most similar to the surveyed vegetation.We conclude that applying quantitative reconstruction methods to individual small sites is, currently, not likely to be useful in complex cultural landscapes. In the context of coppiced woodland, deficiencies in our understanding of pollen taphonomy and the impact of the practice on pollen production first need to be rectified, and we identify strategies to address this situation

Pollen-based quantitative reconstructions of Holocene regional vegetation cover (plant-functional types and land-cover types) in Europe suitable for climate modelling

We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1 degrees x1 degrees spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.Peer reviewe

Fuzzy systems in real-time condition monitoring and fault diagnosis, with a diesel engine case study

Diesel engines have become a common source of power, both for vehicles and for static equipment because they are fuel efficient, robust and reliable. It is important that diesel engines run in their correct condition and properly controlled in order to maintain efficiency, low emissions levels and high reliability.;The following thesis aims to assess the application of fuzzy systems in real-time condition monitoring and fault diagnosis. A 65kW diesel powered generator set has been purchased 'off the shelf' as an example of a typical application which may benefit from the development of CMFD techniques. As a test case, the diesel engine is appropriate as its sub-systems are complex, non-linear and subject to noise and uncertainty.;A diagnostic structure comprising fuzzy systems in three distinct roles has been proposed. Fuzzy reference models, incorporating heuristics and approximate non-linear mathematical relationships, are used for the generation of residuals by comparison with signals from a small number of low cost transducers. The residuals are classified and the diagnosis is inferred from the pattern of residual classes using a fuzzy rule-base. The diagnostic results obtained for three diesel engine sub-systems, show this to be a powerful technique for CMFD system design which may generalised, both for other types of plant and other forms of reference model.;This fuzzy model-based approach to fault diagnosis is shown to have benefits over other techniques by way of its transparency, ease of development, performance under variable engine load conditions, high level output and the lack of any requirement for fault data in the development process.;The robustness of the fuzzy reference models to certain fault conditions remains a key issue. The fuzzy models were generally effective at generating residuals where deviations from the normal condition are small. For larger deviations, robustness of models is not guaranteed or expected. A number of techniques were successfully deployed to reduce the number of misclassifications caused by this lack of robustness

An Industrial Digitalization Platform for Condition Monitoring and Predictive Maintenance of Pumping Equipment

This paper is concerned with the implementation and field-testing of an edge device for real-time condition monitoring and fault detection for large-scale rotating equipment in the UK water industry. The edge device implements a local digital twin, processing information from low-cost transducers mounted on the equipment in real-time. Condition monitoring is achieved with sliding-mode observers employed as soft sensors to estimate critical internal pump parameters to help detect equipment weasr before damage occurs. The paper describes the implementation of the edge system on a prototype microcontroller-based embedded platform, which supports the Modbus protocol; IP/GSM communication gateways provide remote connectivity to the network core, allowing further detailed analytics for predictive maintenance to take place. The paper first describes validation testing of the edge device using Hardware-In-The-Loop techniques, followed by trials on large-scale pumping equipment in the field. The paper concludes that the proposed system potentially delivers a flexible and low-cost industrial digitalization platform for condition monitoring and predictive maintenance applications in the water industry.</jats:p

A stereoselective synthesis of 1,6-diphenyl-1,3,5-hexatrienes utilising 4,4,6-trimethyl-2-vinyl-1,3,2-dioxaborinane as a two-carbon alkenyl building block

A number of 1,6-diphenyl-1,3,5-hexatrienes of varying alkene geometries were stereoselectively prepared from just two starting materials: iodobenzene and 4,4,6-trimethyl-2-vinyl-1,3,2-dioxaborinane via a series of Heck, Suzuki-Miyaura and stereocontrolled iododeboronation reactions. These results demonstrate how 4,4,6-trimethyl-2-vinyl-1,3,2-dioxaborinane can be used as a genuine two-carbon vinyl-dianion building block in stereocontrolled polyene synthesis