89,490 results

  • Chemical control of Poa trivialis on New Zealand racetracks : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University

    Fleming, Philip Brian

    Thesis
    Massey University

    Poa trivialis is a perennial grass weed commonly found in perennial ryegrass (Lolium perenne) racetrack swards throughout New Zealand. Its presence is undesirable as it does not tolerate high wear and is susceptible to dying out over the summer. Two pot trials at Massey University and one field trial carried out at the Awapuni racecourse were conducted during winter and spring 1995 to test the relative susceptibility of Poa trivialis and perennial ryegrass to a wide range of herbicides. A bioassay was also conducted to determine whether herbicide residues from the field trial could affect the germination of perennial ryegrass seed sown soon after treatment. Results showed that none of the chemicals at their chosen respective rates could completely remove Poa trivialis from a racetrack sward in the spring without some damage being caused to perennial ryegrass. Propyzamide and fenoxaprop at rates of 0.2 and 0.15 kg/ha respectively showed the most potential of the chemicals, severely damaging Poa trivialis (causing 50 to 75% reductions) with no adverse effect on perennial ryegrass 8 weeks after spraying. Propyzamide can also provide some control of Poa annua. Fenoxaprop was not improved by increasing the application rate or adding an oil. The performance of fenoxaprop was substantially reduced when applied with either MCPA or a picloram/triclopyr mix. Dalapon and asulam showed good potential to control Poa trivialis but at the high rates tested caused variable or harmful effects to perennial ryegrass. Ethofumesate and chlorpropham applied at rates of 2.0 and 2.5 kg/ha respectively gave inadequate control of Poa trivialis. None of the above herbicides, when used in the field trial resulted in residues which reduced the germination of perennial ryegrass seed sown 3 weeks after spraying. Herbicides tested in the pot trials which showed poor control of Poa trivialis were atrazine, dicamba, isoproturon/diflufenican, linuron, mecoprop, methabenzthiazuron, metsulfuron, pendimethalin, prometryne, thifensulfuron-methyl, triclopyr, and trinexapac-ethyl. Diuron applied at 2.6 kg/ha provided good control of Poa trivialis but caused significant damage to perennial ryegrass. It is concluded that an integrated management approach that incorporates both cultural and chemical techniques will be required to control Poa trivialis on New Zealand racetracks. Future trial work should be carried out on propyzamide applied at rates of 0.2-0.3 kg/ha in autumn to establish the most appropriate time of year to apply this herbicide.

    View record details
  • Rural land subdivision and suburbanisation in the peri-urban area, Kairanga County (1970-1980) : a thesis presented in partial fulfilment of the requirements for the Degree of Master of Arts in Geography at Massey University

    Prangkio, Chira

    Thesis
    Massey University

    After briefly outlining the patterns and processes of rural land subdivision and suburbanisation in other parts of New Zealand, the thesis examines the rural land subdivision regulations and policies throughout the country. The development of a number of small size farmlets in the peri-urban areas has been an indicator of urban expansion in parts of the country. This study is based upon the Kairanga County, a rural area surrounding the city of Palmerston North. In the introduction the county is described as it relates to the rural land subdivision situation. The study of size of holding refers to those farmlets with an area of 20 hectares or less. It was found that most dwellings in the study area which had been built in the 1970s were concentrated upon 'subdivision' land. These farmlets or holdings also illustrated the patterns of change in land use and land holdings. There has been an increase in the number of dwellings in the rural area of the county, especially in 'subdivision' areas, with an average of more than sixteen houses per year. A small percentage of rural 'subdivision' landowners work full-time on their holdings but most of them are employed in non-farming occupations and only carry on part-time farming activities on their lands. There are 61 percent of all those employed in the county engaged in the non-farming occupations. It was found that there are more 'potential' subdivisions than 'actual' subdivisions both in terms of total area and of total numbers of holdings. Most small holdings tend to be located closer to the Palmerston North Urban Area. The total number of holdings has increased because larger holdings have been subdivided into smaller-sized holdings. The area of 'subdivision' land in holdings of 20 hectares or less represents 23 percent of the total occupied land in the county. The land use patterns of 'subdivision' land have changed with a greater variety of land uses and farming types. There was an average of at least two separate types of land use or farming on each holding. Some 5,003 hectares of land in the county has been legally subdivided for smaller farmlets each with an area of 20 hectares or less. When these farmlets become 'actual' subdivisions most of them would be in part for residential use and eventually add to the peri-urban area around Palmerston North City. Finally it was concluded that the pattern and process of suburbanisation of Kairanga County will continue as long as 'potential' subdivision land is available for settlement.

    View record details
  • The effect of ethanol on cortisol metabolism in man : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry at Massey University.

    Evans, Pandora Carlyon

    Thesis
    Massey University

    Methods were developed for the estimation of human plasma cortisol by radioimmunoassay and urinary 6β-hydroxycortisol (6βOHF) by colorimetry after separation by thin layer chromatography (TLC). In addition profiles of urinary neutral steroids were obtained by gas chromatographic separation of methoxime-trimethylsilyl derivatives from urine extracts on a glass capillary column. This approach was found to be more sensitive and reproducible than profile studies based on TLC separation and colorimetric estimation. Pilot studies of the plasma cortisol levels of normal subjects showed a consistent rise in cortisol during alcohol loading under the conditions of the observations, but in hospital patients admitted with acute alcohol intoxication, variability in the experimental conditions masked any consistent changes. Large variations in method reproducibility as well as subject differences affected results from the measurement of 6βOHF and chloroform extractable 17-hydroxycorticosteroids in one normal and four alcoholic subjects, rendering apparent initial differences insignificant. The results suggest, but do not demonstrate, that alcohol ingestion may divert normal cortisol metabolism into a pathway leading to the production of 6βOHF. Urinary steroid profiles obtained from two normal subjects, one normal subject under conditions of alcohol load and one alcoholic subject suggest that any effects of alcohol on cortisol metabolism are subtle and would require study of a large number of cases to define them. This work has served to delineate the faults and potential of various approaches to the study of cortisol metabolism and the possible effects of alcohol thereon. It would seem that their application in carefully designed and well controlled experiments to a larger number of subjects is necessary to obtain the information desired.

    View record details
  • The chief executive and aspects of change : a thesis presented in partial fulfilment of the requirements for the degree of Master of Business Administration in Agriculture at Massey University

    Smith, Robin W. N.

    Thesis
    Massey University

    This research is directed to an analysis of certain change related variables, (e.g. competitive/innovative attitudes and postures), that are influential in determining a Chief Executives perception and choice of growth strategies available within his companies future. It attempts an analysis of the interaction on the change dimension of a management culture and its operating environment. For purposes of contrast this culture was in part defined by the levels of conservatism found in the Chief Executive personality. A national sample was drawn from among Chief Executives of the larger, (fifty employees plus), New Zealand Commercial enterprise. A measure was developed from the work and findings of a conservatism theorist, G. Wilson to sample sort for respondents who would fall within one of two groups at the extremes of a range of conservatism (Very Low/Very High). Significant relationships were identified that indicated determining influences by Executive personalities and attitudes on the growth and change futures of the organisations they managed; in turn this has re-emphasized the need to more fully recognize that the behavioural characteristics of the firm and its leadership are at least of equal significance with the structural in shaping-out organisational futures.

    View record details
  • The effect of heat treatment on lysine availability and dye binding capacity of skim milk : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology at Massey University

    Reeves, Malcolm John

    Thesis
    Massey University

    The reported work on changes in lysine content in milk and dried milk is examined. The cause of these losses, the Maillard reaction, and the methods of lysine determination are discussed. All methods have recognised faults. Little information is available to the food processor regarding the kinetics of these losses, and the methods of their determination are not simple enough for routine quality control application. Although the lysine content of milk products determined after acid hydrolysis is known to be higher than nutritional studies indicate the causes of this are being established. Therefore acid hydrolysis in conjunction with a GLC method of amino acid analysis was adopted after some modification. (It was found that dialysis of the milk prior to hydrolysis resulted in cleaner chromatograms and that as the recovery of several amino acids, such a proline, leucine, and isoleucine, was not affected by heat treatment then these were used as internal 'internal standard'.) No simple rate expression could be found to fit the kinetics of the loss of acid released lysine. A first order model requiring the losses to be increased by a factor of 3.43 was devised and this could be used to satisfactorily predict values for acid available lysine in the heat treated milk. The possibility of the 3.43 factor being due to the regeneration of lysine by acid from Maillard intermediates, although requiring assumptions, was found to be not unreasonable. The energy of activation of the reaction leading to a loss in acid released lysine at 31.5 Kcal/mole is similar to literature values while the model value of 37.2 Kcal/mole is rather higher. The literature findings of little or no loss of lysine during pasteruization, evaporation, and sterilization of milk are supported. The technique of protein determination by dye binding was examined and applied to following changes in lysine in heat treated milk. The inconsistencies in reported work on dye binding is of little consequence as relative changes only are required. Changes in dye binding using amido black did not follow simple order kinetics, even when allowance was made for the constant binding by arginine and histidine. A first order model requiring the changes to be increased by a factor of 3.68 was developed. About 46% of this factor can be explained by assuming constant binding by arginine and histidine, the remainder of the factor possibly being due to Maillard intermediates binding dye, and/or a change in binding stoichiometry occurring. From the model it is possible to predict the observed changes in dye binding. Literature findings were supported. The energy of activation for the dye binding changes is 28.6 Kcal/mole, and for the model, 30.8 Kcal/mole. Ancillary investigations showed that the concurrent colour changes due to heat treatment have an energy of activation of about 30 Kcal/mole, and that there is a relationship between colour and dye binding capacity in heat treated milk. The relationship between the Pro-Milk and a typical absorbance spectrophotometer was determined, and an expression found which would enable a spectrophotometer to be used for protein determination.

    View record details
  • Effect of cultivation on maize response to nitrogen fertilizer : a thesis presented in partial fulfillment of the requirements for the degree of Master in Applied Science in Soil Science, Institute of Natural Resources, Massey University, Palmerston North, New Zealand

    Munir, Sulhadiana

    Thesis
    Massey University

    Continuous cultivation of arable soils results in the decline of 'soil quality' in terms of structural degradation and nutrient depletion. It decreases soil organic matter content, induces the leaching and gaseous losses of N through enhanced nitrification and denitrification, resulting in the depletion of nitrogen content of the soils. This will affect N availability, soil moisture retention, soil aeration and the activity of soil microorganisms. The objective of this study is to examine the effect of cultivation on the response of maize to N fertiliser. A glass house experiment was conducted using four soils. The soils included a permanent pasture soil and three maize / barley grown soils which have been cultivated for 6, 17 and 34 years. Maize plants were grown at six levels of N applied as urea (0 - 500 kg N/ha). The dry matter yield response to N application indicated higher maize growth for the pasture soil than for the cultivated soils at all levels of N application. Even at the highest level of N application (500 kg N/ha) the maize dry matter yield for the cultivated soil did not reach that for the unfertilised pasture soil. This indicates that N alone was not limiting the dry matter yield among the cultivated soils. It was hypothesised that the differences in the physical conditions among these soils may also be responsible for differences in dry matter yield. In the second experiment, pasture and the 34 year cultivated soils were incubated with poultry manure for eight weeks. The addition of poultry manure was to improve the physical conditions of the soil. A glasshouse experiment was then conducted to examine the effect of poultry manure addition on the growth of maize at five levels of N (0-400 kg N/ha) applied as urea. There was a clear visual indication of an improvement in the structure of the cultivated soil due to the incorporation of poultry manure. Addition of poultry manure increased the dry matter yields of maize plants both in the cultivated and the pasture soils. The dry matter yield of plants in the cultivated soils (in the presence of manure addition) was higher than the pasture soils at low levels of N application and similar yields were obtained at the higher rates of N application. Oxygen diffusion rate (ODR) values were higher for the pasture soil than the cultivated soil. The addition of poultry manure in the initial stages, however, decreased the ODR values in both soils which is attributed to the increased consumption of oxygen by the easily decomposable organic carbon in the poultry manure. With increasing time after incubation the ODR values slowly increased in the poultry manure treated soils indicating an improvement in soil structure. The study clearly demonstrated that the impact of cultivation on maize yield was partly due to poor soil physical conditions.

    View record details
  • Froth regime point efficiency for gas-film controlled mass transfer on a two-dimensional sieve tray

    Lockett, MJ; Kirkpatrick, Robert; Uddin, MS (1979)

    Journal article
    The University of Auckland Library

    View record details
  • Dynamic modelling and validation of a commercial scale geothermal organic rankine cycle power plant

    Proctor, MJ; Yu, Wei; Kirkpatrick, Robert; Young, Brent (2016-05)

    Journal article
    The University of Auckland Library

    The organic rankine cycle (ORC) is a heat recovery technology used for renewable energy generation such as the large-scale production of electricity from geothermal resources. In this paper a dynamic model of a commercial-scale geothermal ORC is developed in process simulation software and validated against plant data. The difference in power output between the model and plant was found to be 0.24% with a standard deviation of 1.40% of the average power output. The results from model validation are used to suggest improvements to the model, which is intended to be used for further investigation of optimisation and process control.

    View record details
  • Side draw optimisation of a high-purity, multi-component distillation column

    Kraller, MA; Udugama, IA; Kirkpatrick, Robert; Yu, Wei; Young, Brent (2016-11)

    Journal article
    The University of Auckland Library

    Distillation columns with side draws are widely used in the process industry to refine crude methanol into high-purity methanol. Historically, industrial methanol manufacturers have concentrated on meeting strict product specifications, while methanol yield and reboiler duty optimisation has often been neglected. In this work, a steady-state model of an industrial high-purity multi-component methanol distillation column was developed using a commercial process simulator. To achieve higher recovery at optimal reboiler duty, the side draw location and side draw mass flow rates were identified as two important factors. It was determined that a combination of lowering the side draw location while reducing the side draw mass flow rate will lead to the most optimal outcome. A design of experiment was also carried out to evaluate the stability of the column at recovery rates of 97.7% (current recovery) and 99.5% (proposed high recovery). Disturbances in the feed stream were identified as having the greatest effect, while the product purity was observed to become more sensitive towards all disturbances when operating at an enhanced recovery.

    View record details
  • A texture-processing model of the 'visual sense of number'

    Morgan, M; Raphael, S; Tibber, M; Dakin, Steven (2014-09-07)

    Journal article
    The University of Auckland Library

    It has been suggested that numerosity is an elementary quality of perception, similar to colour. If so (and despite considerable investigation), its mechanism remains unknown. Here, we show that observers require on average a massive difference of approximately 40% to detect a change in the number of objects that vary irrelevantly in blur, contrast and spatial separation, and that some naive observers require even more than this. We suggest that relative numerosity is a type of texture discrimination and that a simple model computing the contrast energy at fine spatial scales in the image can perform at least as well as human observers. Like some human observers, this mechanism finds it harder to discriminate relative numerosity in two patterns with different degrees of blur, but it still outpaces the human. We propose energy discrimination as a benchmark model against which more complex models and new data can be tested.

    View record details
  • The influence of approach velocity on bubble coalescence

    Kirkpatrick, Robert; Lockett, MJ (1974-12)

    Journal article
    The University of Auckland Library

    Experiments have been carried out in which a cloud of air bubbles has been prevented from rising by downflowing water in a tube. High speed photography revealed an almost complete absence of bubble coalescence. This has been attributed to the large approach velocities of bubbles in the cloud. Further experiments in which a single bubble has been allowed to coalesce with a plane air???water interface have demonstrated the effect more clearly. Two basic types of bubble coalescence have been recognised depending on the approach velocity of the bubbles. At a low approach velocity, bubble coalescence is rapid, but coalescence times are considerably increased at large approach velocities. For pure liquids, a theory is put forward which shows that at low approach velocities film rupture can occur before the approaching bubbles are brought to rest. At large approach velocities the bubbles are brought to rest before rupture occurs. In the latter case bubble bounce can occur and the total coalescence time is thereby considerably increased. Based on observed approach velocities in a stationary bubble cloud, it is suggested that large approach velocities in a bubble column may be an important factor in limiting bubble coalescence.

    View record details
  • Number and density discrimination rely on a common metric: Similar psychophysical effects of size, contrast, and divided attention

    Tibber, MS; Greenwood, JA; Dakin, Steven (2012-06)

    Journal article
    The University of Auckland Library

    While observers are adept at judging the density of elements (e.g., in a random-dot image), it has recently been proposed that they also have an independent visual sense of number. To test the independence of number and density discrimination, we examined the effects of manipulating stimulus structure (patch size, element size, contrast, and contrast-polarity) and available attentional resources on both judgments. Five observers made a series of two-alternative, forced-choice discriminations based on the relative numerosity/density of two simultaneously presented patches containing 16???1,024 Gaussian blobs. Mismatches of patch size and element size (across reference and test) led to bias and reduced sensitivity in both tasks, whereas manipulations of contrast and contrast-polarity had varied effects on observers, implying differing strategies. Nonetheless, the effects reported were consistent across density and number judgments, the only exception being when luminance cues were made available. Finally, density and number judgment were similarly impaired by attentional load in a dual-task experiment. These results are consistent with a common underlying metric to density and number judgments, with the caveat that additional cues may be exploited when they are available.

    View record details
  • A comparison of a novel robust decentralised control strategy and MPC for industrial high purity, high recovery, multicomponent distillation

    Udugama, IA; Wolfenstetter, F; Kirkpatrick, Robert; Yu, Wei; Young, Brent (2017-07)

    Journal article
    The University of Auckland Library

    In this work we have developed a novel, robust practical control structure to regulate an industrial methanol distillation column. This proposed control scheme is based on a override control framework and can manage a non-key trace ethanol product impurity specification while maintaining high product recovery. For comparison purposes, a MPC with a discrete process model (based on step tests) was also developed and tested. The results from process disturbance testing shows that, both the MPC and the proposed controller were capable of maintaining both the trace level ethanol specification in the distillate (XD) and high product recovery (??). Closer analysis revealed that the MPC controller has a tighter XD control, while the proposed controller was tighter in ?? control. The tight XD control allowed the MPC to operate at a higher XD set point (closer to the 10ppm AA grade methanol standard), allowing for savings in energy usage. Despite the energy savings of the MPC, the proposed control scheme has lower installation and running costs. An economic analysis revealed a multitude of other external economic and plant design factors, that should be considered when making a decision between the two controllers. In general, we found relatively high energy costs favour MPC.

    View record details
  • Ideal bubbly flow and actual flow in bubble column

    Lockett, MJ; Kirkpatrick, Robert (1975)

    Journal article
    The University of Auckland Library

    View record details
  • A template for change? De-risking the transition to CDIO

    Robinson, K; Friedrich, Heide; Kirkpatrick, Robert; Nicholas, C; Rowe, G (2013)

    Journal article
    The University of Auckland Library

    This paper provides a case study on how an established, mature engineering faculty, with a large population of students can make the successful, high risk, step change transition towards the delivery of CDIO objectives: ???Graduating engineers who can conceive-design-implement-operate complex value-added engineering systems in a modern team-based environment??? (Crawley et al, 2011). The successful results of the project demonstrated the effectiveness of the systems thinking and CDIO approach, and endorsed this as the basis for a major change strategy. Not only did it demonstrate the quality of all the students on the course, their potential and commitment to engineering, but it also demonstrated willingness of the faculty to take a risk and to embrace change. The project scenario opened up an otherwise overlooked teaching resource: that of practitioner lecturers with many years of experience of implementation and operation of major projects. These skills were essential to the scoping, design, planning and implementation of the project as well as giving the backdrop of best practice from industry. Auckland???s experience of introducing a major step change may be used as a template for other universities who may wish to follow Auckland???s example. This project shows the value of a hearts and minds approach to change as it brought together students, staff and best practice under a multidisciplinary systems thinking and CDIO approach; all united in the interests of reconstructing Christchurch.

    View record details
  • Synthesis of tunichrome Sp-1

    Pullar, MA; Barker, David; Copp, Brent (2015-10-07)

    Journal article
    The University of Auckland Library

    The first total synthesis of the ascidian blood pigment tunichrome Sp-1 is reported, with the modified pentapeptide prepared in a convergent manner using a combination of solid-phase peptide synthesis, Hunsdiecker decarboxylative iodination and Buchwald amidation reaction chemistry. The natural product was shown to exist as a mixture of trans- and cis-prolyl conformers, with the former dominating in a 5:1 ratio.

    View record details
  • Ontogeny and control of the heart rate power spectrum in the last third of gestation in fetal sheep

    Koome, ME; Bennet, Laura; Booth, LC; Davidson, Joanne; Wassink, Guido; Gunn, Alistair (2014-01)

    Journal article
    The University of Auckland Library

    Power spectral analysis of fetal heart rate variability has been proposed to provide a non-invasive estimate of autonomic balance. However, there are few systematic data before birth. We therefore examined developmental changes in the frequency power spectrum at very low (0-0.04 Hz), low (0.04-0.15 Hz) and high (0.15-0.4 Hz) frequencies, and the ratio of low- to high-frequency power (LF/HF) in chronically catheterised, healthy fetal sheep at 0.6 (n = 8), 0.7 (n = 7) and 0.8 gestation age (ga, n = 11). In a second study, 0.8 ga fetuses received either atropine (4.8 mg bolus, then 4.8 mg/h for 30 minutes, n = 6) or 6-hydroxydopamine (6-OHDA, 20 mg/ml at 2.5 ml/h for 3 h, n = 9). Data were analysed by sleep state defined by low voltage-high frequency (LV) or high voltage-low frequency (HV) EEG. Total spectral power increased with gestational age (P < 0.05), while LF/HF decreased from 0.6 to 0.7 ga. At 0.8 ga, heart rate and LF/HF were significantly higher during HV than LV sleep (P < 0.05). Consistent with this, although total spectral power was not significantly greater during HV sleep, there was a significant interaction between sleep state and frequency band (P = 0.02). Both atropine (P = 0.05) and 6-OHDA (P < 0.05) were associated with an overall reduction in spectral power but no significant effect on the LF/HF ratio. This study does not support substantial, consistent differences between the frequencies of sympathetic and parasympathetic activity in late gestation fetal sheep.

    View record details
  • Testing for new physics: Neutrinos and the primordial power spectrum

    Canac, N; Aslanyan, G; Abazajian, KN; Easther, Richard; Price, LC (2016-09)

    Journal article
    The University of Auckland Library

    We test the sensitivity of neutrino parameter constraints from combinations of CMB and LSS data sets to the assumed form of the primordial power spectrum (PPS) using Bayesian model selection. Significantly, none of the tested combinations, including recent high-precision local measurements of H0 and cluster abundances, indicate a signal for massive neutrinos or extra relativistic degrees of freedom. For PPS models with a large, but fixed number of degrees of freedom, neutrino parameter constraints do not change significantly if the location of any features in the PPS are allowed to vary, although neutrino constraints are more sensitive to PPS features if they are known a priori to exist at fixed intervals in log k. Although there is no support for a non-standard neutrino sector from constraints on both neutrino mass and relativistic energy density, we see surprisingly strong evidence for features in the PPS when it is constrained with data from Planck 2015, SZ cluster counts, and recent high-precision local measurements of H0. Conversely combining Planck with matter power spectrum and BAO measurements yields a much weaker constraint. Given that this result is sensitive to the choice of data this tension between SZ cluster counts, Planck and H0 measurements is likely an indication of unmodeled systematic bias that mimics PPS features, rather than new physics in the PPS or neutrino sector.

    View record details
  • Intelligent condition assessment of power transformers

    Peimankar, Abdolrahman (2017)

    Doctoral thesis
    University of Canterbury Library

    This thesis begins by providing an introduction to different transformer failures and the most effective condition monitoring techniques. Different failures are introduced and their corresponding fault diagnosis methods are listed to have a better understanding of failure modes and their consequence effects. An investigation into monitoring major failures of transformers using dissolved gas analysis is then presented. Various conventional, dissolved gas analysis based, fault diagnosis techniques are presented and the drawbacks of these methods are discussed. Intelligent fault diagnosis methods are introduced to overcome the problems of the conventional techniques. An overview of statistical and machine learning algorithms applied in this research is also described. Preliminary research results on transformer load tap changers fault classification are reported. A hierarchical fault diagnosis algorithm for transformer load tap changers using support vector machines is used, in which, for each fault class, a unique single support vector machine algorithm is employed. However, while the developed algorithm is reasonably accurate, the shortcomings of applying single learning algorithms are discussed and a proposal for developing a more robust and generalised transformers condition assessment algorithm is made. An intelligent power transformer fault diagnosis algorithm is then developed to classify faults of transformers. The proposed fault diagnosis algorithm is an ensemble-based approach which uses different statistical and machine learning algorithms. In the first phase of the proposed algorithm the most relevant features (dissolved gases) corresponding to each fault class are first determined. Then, selected features are used to classify transformer faults. The results of this algorithm show a significant improvement, in terms of classification. A time-series forecasting algorithm is developed to predict future values of dissolved gases in transformers. The dataset for this algorithm was collected from a transformer for a period of six months which consisted of seven dissolved gases, a loading history, and three measured, ambient, oil, and winding, temperatures of transformer. The correlation coefficients between these 11 time series are then calculated and a nonlinear principle component analysis is used to extract an effective time series from highly correlated variables. The proposed multi-objective evolutionary time series forecasting algorithm selects the most accurate and diverse group of forecasting methods among various implemented time series forecasting algorithms. The proposed method is also compared with other conventional time series forecasting algorithms and the results show the improvements over the different forecasting horizons.

    View record details
  • Genetic factors associated with orthodontic pain in children and adolescents: a pilot study

    Sew Hoy, William Hugh (2017)

    Doctoral thesis
    University of Otago

    Introduction: Pain is often reported as being the worst aspect of orthodontic treatment. Nearly all patients experience pain and discomfort at their teeth at some point during orthodontic treatment. Little information exists on the severity of pain in the latter stages of orthodontic treatment. In addition, no studies have investigated the role of genetic factors on pain caused by fixed appliances. Objectives: To investigate whether demographic, clinical or genetic factors are associated with the severity of pain experienced following adjustment of fixed orthodontic appliances. Methods: Eighty-two participants undergoing fixed orthodontic treatment were recruited. Baseline DNA was collected via blood or saliva samples. Immediately after bond-up or an adjustment of the fixed appliances, the participants used a smartphone app to record regular pain scores at their teeth over the following three days. Results: Pain peaked approximately 19 hours after the orthodontic adjustment, then gradually returned toward baseline levels by day three. Pain on chewing was significantly greater than the resting pain at the teeth at all time points concerned. There was a significant difference in the total amount of pain at the teeth over the three days when comparing bond-ups to no arch wire changes (with or without bends placed). Gender, age, and time in treatment were not associated with the severity of pain experienced after an orthodontic adjustment. The rs931233 SNP of the HTR2A and the rs4646310 SNP of the COMT genes were significantly associated with pain severity. Haplotypes of the COMT gene also showed promising, although non-significant associations with pain severity. Conclusions: Pain on chewing is significantly more painful compared to resting pain at the teeth after adjustment of fixed appliances. SNPs of the HTR2A and COMT gene were associated with the severity of pain following adjustment of fixed appliances. Therefore, it seems that genetic factors have a modifying effect on orthodontic pain (as is the case with many other pain conditions such as TMD, fibromyalgia, and experimental pain). Larger samples are required to investigate these associations further.

    View record details