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    Adopting augmented reality to avoid underground utilities strikes during excavation : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy, School of Built Environment, College of Science, Massey University, New Zealand
    (Massey University, 2025) Khorrami Shad, Hesam
    The construction industry constantly pursues innovative methods to improve safety, enhance productivity, and reduce costs and project durations. Augmented Reality (AR) is a promising technology, potentially bringing about transformative changes in construction. AR is a promising technology for visualizing data in construction sites and preventing clashes and accidents. One of its promising applications is in the excavation sector, where accidental strikes on underground utilities pose serious safety risks, delays, and costly damages. However, while AR has gained increasing attention in recent years, its integration into construction practice remains limited. To address this limitation, this research investigates the potential of AR to facilitate identifying underground utility locations through a systematic review, industry engagement, and user-centred experimentation. Initially, a systematic literature review was conducted to explore the current applications of AR in construction safety. This review identified the safety purposes of AR across three project phases: pre-event (e.g., training, safety inspections, hazard alerting, enhanced visualization), during-event (e.g., pinpointing hazards), and post-event (e.g., safety estimation). However, the review also revealed a notable lack of studies focused on AR applications in excavation activities, particularly for underground utility strike prevention. In response, a study was undertaken to understand the needs, expectations, and challenges associated with adopting AR in the excavation sector. 31 professionals from the excavation industry participated in the within-subject experiment, interacting with two AR prototypes, delivered via Optical See-Through (OST) and Video See-Through (VST) devices. The findings indicated a clear preference for AR over traditional methods such as paper-based drawings. Participants showed a preference for VST rather than OST, given their familiarity with VST devices such as tablets. Further, accessibility emerged as the primary barrier to adopting AR within the excavation industry. Building on the literature and industry insights, an experimental study was designed to evaluate the effectiveness of different AR visualization methods in underground utility detection. A within-subject experiment involving 60 participants was conducted to compare four of the most cited visualization techniques for underground utilities: X-Ray, Shadow, Cross-Sectional, and a newly developed Combination method. Drawing on the Theory of Affordances and Task Load analysis, the study found that the Combination and X-Ray visualization methods perform superior to the Shadow. These results provide empirical support for the user-centered design of AR visualization techniques in excavation practice. This research contributes to the fields of human-computer interaction, construction safety, and digital technology adoption by advancing the use of AR for underground utility strike prevention. The study shifts the focus of AR from general safety training to real-time, spatial visualization for excavation, offering both theoretical insights and practical applications. Methodologically, it follows a structured mixed-methods approach, combining literature review, industry engagement, and experimental testing. Practically, it identifies user preferences, visualization methods, and key adoption factors such as usability and accessibility. Overall, this thesis fills the gap between emerging AR technologies and their integration into safer excavation practices.
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    Grape yield analysis with 3D cameras and ultrasonic phased arrays : a thesis by publications presented in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Albany, New Zealand
    (Massey University, 2024-01-18) Parr, Baden
    Accurate and timely estimation of vineyard yield is crucial for the profitability of vineyards. It enables better management of vineyard logistics, precise application of inputs, and optimization of grape quality at harvest for higher returns. However, the traditional manual process of yield estimation is prone to errors and subjectivity. Additionally, the financial burden of this manual process often leads to inadequate sampling, potentially resulting in sub-optimal insights for vineyard management. As such, there is a growing interest in automating yield estimation using computer vision techniques and novel applications of technologies such as ultrasound. Computer vision has seen significant use in viticulture. Current state-of-the-art 2D approaches, powered by advanced object detection models, can accurately identify grape bunches and individual grapes. However, these methods are limited by the physical constraints of the vineyard environment. Challenges such as occlusions caused by foliage, estimating the hidden parts of grape bunches, and determining berry sizes and distributions still lack clear solutions. Capturing 3D information about the spatial size and position of grape berries has been presented as the next step towards addressing these issues. By using 3D information, the size of individual grapes can be estimated, the surface curvature of berries can be used as identifying features, and the position of grape bunches with respect to occlusions can be used to compute alternative perspectives or estimate occlusion ratios. Researchers have demonstrated some of this value with 3D information captured through traditional means, such as photogrammetry and lab-based laser scanners. However, these face challenges in real-world environments due to processing time and cost. Efficiently capturing 3D information is a rapidly evolving field, with recent advancements in real-time 3D camera technologies being a significant driver. This thesis presents a comprehensive analysis of the performance of available 3D camera technologies for grape yield estimation. Of the technologies tested, we determined that individual berries and concave details between neighbouring grapes were better represented by time-of-flight based technologies. Furthermore, they worked well regardless of ambient lighting conditions, including direct sunlight. However, distortions of individual grapes were observed in both ToF and LiDAR 3D scans. This is due to subsurface scattering of the emitted light entering the grapes before returning, changing the propagation time and by extension the measured distance. We exploit these distortions as unique features and present a novel solution, working in synergy with state-of-the-art 2D object detection, to find and reconstruct in 3D, grape bunches scanned in the field by a modern smartphone. An R2 value of 0.946 and an average precision of 0.970 was achieved when comparing our result to manual counts. Furthermore, our novel size estimation algorithm was able accurately to estimate berry sizes when manually compared to matching colour images. This work represents a novel and objective yield estimation tool that can be used on modern smartphones equipped with 3D cameras. Occlusion of grape bunches due to foliage remains a challenge for automating grape yield estimation using computer vision. It is not always practical or possible to move or trim foliage prior to image capture. To this end, research has started investigating alternative techniques to see through foliage-based occlusions. This thesis introduces a novel ultrasonic-based approach that is able to volumetrically visualise grape bunches directly occluded by foliage. It is achieved through the use of a highly directional ultrasonic phased array and novel signal processing techniques to produce 3D convex hulls of foliage and grape bunches. We utilise a novel approach of agitating the foliage to enable spatial variance filtering to remove leaves and highlight specific volumes that may belong to grape bunches. This technique has wide-reaching potential, in viticulture and beyond.
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    Estimating grapevine water status using hyperspectral and multispectral remote sensing and machine learning algorithms : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Agriculture and Horticulture at Massey University, Manawatū, New Zealand
    (Massey University, 2023) Wei, Hsiang-En
    Moderate water deficit is desirable for achieving the optimal grape composition which determines the values of wine, especially for red cultivars. To attain consistency in grape quality in vineyards, it is critical to manage grapevine water status (GWS) to the target range, but to avoid severe dehydration, between fruit set and veraison. Together with the foreseeable climate changes and stricter environmental regulations, there is a need for viticulture to estimate GWS variability across fields along growing seasons before irrigating to eliminate the uncertainty of controlling hydration status and to produce consistent grapes with premium quality. Precision viticulture (PV) recognizes that not all areas within a vineyard are uniform in terms of their soil, climate, and other environmental conditions. Therefore, it tailors viticultural management to the unique needs of different vineyard zones by focusing on applying site-specific or time-specific management practices. PV aims to enhance grape quality and yield while minimizing resource usage and environmental impacts. As the final product (wine) for viticulture has the potential of high additional values, it is worth considering the application of PV in decision-making according to the information on spatio-temporal variability across the fields. The advancement and availability of remotely sensed spectral information, geospatial technologies, and machine learning models have opened a new chapter for spatio-temporal GWS monitoring. However, there are technical shortcomings that need to be addressed before extensive application and adoption of these techniques in viticulture. These include a lack of understanding of GWS-related spectral data analysis methods, a lack of data interoperability for GWS estimation between data sourced from various devices with different formats, and a lack of availability of high-coverage images with high spatial and temporal resolution. Therefore, this study tackled the technical bottlenecks, related to the application of proximal sensing and remote sensing (RS) in GWS estimation, from three perspectives: (i) the exploration of relevant spectral regions over the electromagnetic spectrum, (ii) the complementation from differently sourced datasets other than RS information, (iii) the provision of large-scale GWS prediction. This study was undertaken in two Pinot Noir vineyards trained with vertical shoot positioning for two growing seasons in Martinborough, New Zealand. The investigation window, corresponding to the critical periods of GWS management, between fruit set and veraison in each growing season, includes November, December, January, and February. Stem water potential (Ψstem), serving as a proxy for GWS, is measured on 85 and 63 canopies in the first and second growing seasons. Each sampled grapevine is recorded for its location with a global navigation satellite system with real-time kinematic correction. Five times field data collection, including measuring hyperspectral point data using ASD FieldSpec 4 Spectroradiometer (proximal sensing data) and taking multispectral images using DJI Phantom 4 UAV (remote sensing data), were carried out in each growing season. An electromagnetic induction survey was implemented by using EM38-MK2 to acquire apparent electrical conductivity (ECa) maps (complementary data). Several satellite images collected by PlanetScope (remote sensing data) during the study periods and the LiDAR-based digital elevation model (complementary data) were downloaded and added to the analysis datasets. An on-site weather station continuously records and provides meteorological information, including air temperature (°C), relative humidity (%), rainfall (mm), wind speed (km/h), and irradiance (W/m2) (complementary data). The identification of the relationships between spectral information and Ψstem is an essential step for the robust application. By analyzing hyperspectral spectra, it shows that the statistically relevant wavelengths disperse across visible, near-infrared, and shortwave infrared (SWIR) spectral bands. They are specifically located around blue, red, and red edge bands, two weak water absorption bands at 970 and 1200 nm, two strong absorption bands at 1400 and 1940 nm, and some dry matter-related bands. When analyzing multispectral images taken by UAV, it shows Transformed Chlorophyll Absorption Reflectance Index and Excess Green Index are the multispectral indices mostly correlated (R2 = 0.35 and 0.3, respectively) with the changes in Ψstem. It implies that the variation in leaf pigments, especially chlorophylls, is better for describing the Ψstem variation of Pinot Noir than the alteration in canopy structure. When applying the Ψstem-sensitive spectral bands through airborne or spaceborne platforms, the missing SWIR for most commercial multispectral sensors and the presence of vapor in the air obstruct the usefulness of the Ψstem-sensitive spectral bands. Therefore, this study assesses the complementary effects provided by other environmental aspects, including soil/ terrain, vegetation, temporal, and weather variables, to improve the GWS estimating capabilities of aerial multispectral sensors. The results prove the complementary effects by displaying that the detection accuracy is improved from RMSE of 213 to 146 kPa and RMSE of 221 kPa to 138 kPa. To monitor the fields at a large-scale using multispectral satellites, it is common to encounter several technical issues: coarse resolution pixels that contain background information, weather dependence, and delay in the image delivery. This study addresses the limitation of coarse spatial resolution using two-stage calibration to scale information provided by ground measurement up to satellite images, along with removing interference from the inter-row components. It demonstrates that satellite images can approximate the collected Ψstem with high accuracy (RMSE = 59 kPa). To deal with the contamination by weather and delivering delay of image products, a prediction model is established based on the calibrated satellite images and various environmental variables (day of the year, rainfall, potential evapotranspiration, irrigation, fertigation, plucking, trimming, normalized difference vegetation index, ECa, elevation, and slope). The developed model is able to predict Ψstem trend in an independent growing season with high consistency when compared with the reference (r = 0.89 and 0.87 for the two vineyards, respectively).
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    Surface pasteurisation of fresh chicken meat using UV-C technology : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Albany, New Zealand
    (Massey University, 2019) Philip, Arthur Jonathan
    Fresh chicken meat is highly susceptible to contamination by spoilage and pathogenic microorganisms due to its high-water activity and rich nutrients. Following processing, aerobic mesophilic count (AMCs) on the surface of fresh chicken samples ranges from 3.00 to 4.00 log CFU/cm2. The New Zealand food safety guidelines stipulate that aerobic mesophilic counts (AMCs) present on surfaces of fresh chicken portion should be <6 log CFU/cm2 by end of shelf-life (6-7 days) when stored at 4°C. Hence, the safety and shelf-life of fresh chicken meat pose challenges for the industry. The UV-C technology, is a novel food processing technique that has lethal germicidal capability at 280-290 nm. Therefore, the technology has a potential to decontaminate suitable food products including the surfaces of fresh poultry portions. This study investigated the effect of UV-C light processing on untreated fresh skinless and skin-on chicken portions. The study was conducted in 2 phases to optimise the processing technology and determine its effects on fresh chicken samples during storage (4°C). One day old fresh chicken samples (skinless breast fillet, skinless thigh fillet, skin-on breast fillet, and skin-on thigh fillet) were obtained from a commercial processing factory and transported to Massey University, Auckland Campus, under chilled conditions (4°C) within an hour. In phase one, the fresh chicken samples were treated with four UV-C dosages (50, 100, 200, and 300 mJ/cm2) at ambient temperature (20°C) using a commercial UV disinfection system. AMCs were determined by swabbing the fresh chicken samples using swabs and 5-cm2 templates. Suitable dilutions (10-1 up to 10-6) of the swabbed samples were enumerated on standard plate agar with incubation at 30°C/72 h and grown colonies were expressed as log CFU/cm2. Temperature of the chicken samples before and after UV-C treatments was measured using a 20-cm probe thermometer. Treatment time was recorded automatically by the UV-C equipment. Phase one results showed that 50 mJ/cm2 was capable of maximum microbial reduction (skinless: 1.69 log CFU/cm2; skin-on: 0.21 log CFU/cm2) with minimal temperature changes (skinless: 3.14°C; skin-on: 3.32°C) and lowest exposure times (skinless: 2.17 minutes; skin-on: 2.22 minutes.). Therefore, 50 mJ/cm2 was selected as the optimum dosage for skin-on and skinless fresh chicken samples. In phase 2, the effect of optimised UV-C light dosage (50 mJ/cm2) on fresh chicken samples stored at 4°C/7 days was investigated. Instrumental color analysis, AMCs and lipid oxidation were determined at 4 different time points (day 0, 3, 5, 7) during storage (4°C). AMCs were analysed as previously described. The detection of E.coli, S. aureus, L. monocytogenes, Campylobacter spp. and Salmonella spp. were conducted at 0 and 7 days of storage using standard methods, while colour was measured by a colorimeter. Lipid oxidation was analysed by the thiobarbituric acid (TBA) method. Consumer sensory evaluation was carried out to evaluate raw and cooked chicken samples during storage. Raw chicken samples were evaluated by a focus group consisting of 5 semi-trained panelists at days 1, 5, and 7 while cooked samples were evaluated on days 1 and 7 by 30 panelists using a 9-scale hedonic test. For cooked chicken portions, samples were cooked to an internal temperature of 75°C using a convection oven. The cooked chicken samples were cooled to between 30 – 40°C before being served to the sensory panelists. The result of phase 2 showed that the initial mean AMCs were 3.31 ± 0.11 (skin-on) and 3.80 ± 0.35 (skinless) log CFU/cm2. After UV-C treatment, the AMCs of UV-treated chicken samples were reduced to 1.87 ± 0.98 (skinless) and 3.07 ± 0.34 (skin-on) log CFU/cm2, indicating that the AMCs for skinless and skin-on chicken samples decreased by 1.93 log and 0.24 log CFU/cm2 after UV-C (50 mJ/cm2) treatment, respectively. At the end of storage, the AMCs on skin-on chicken breast samples were 8.57 ± 0.34 (untreated) and 7.48 ± 0.07 (UV- treated) log CFU/cm2. Whereas, AMCs on skinless breast fillet were 8.62 ± 0.35 (untreated) and 6.73 ± 1.10 (UV-treated) log CFU/cm2, respectively. The results indicated that the growth of AMCs on untreated chicken samples exceeded the recommended limit on day 5, while UV-treated chicken samples were higher than the recommended limit on day 6 (skin- on) and day 7 (skinless). In addition, the AMCs results suggested that UV-C treatment was more effective on skinless chicken portion. Furthermore, pathogenic bacteria (E.coli, S. aureus, L. monocytogenes, Campylobacter spp., and Salmonella spp.) were not detected on untreated and UV-treated chicken samples on days 0 and 7 of storage, indicating the effectiveness of the chlorinated chilling processing step. Based on the Hunter L*, a*, b* colour readings and TBA (TBARS) results, the applied UV-C dose (50 mJ/cm2) had minimal impact on the color and lipid oxidation of both skin-on and skinless chicken samples during storage. However, a faint burnt odor was detected by sensory panelists during evaluation of UV-C treated fresh (raw) chicken samples stored (4°C) for day 1. The panelists did not detect any unpleasant odor from the cooked chicken samples during storage. Therefore, the results suggested that UV-C light may offer good prospects for shelf-life extension of fresh chicken samples. In addition, the results also indicated that UV-C light surface pasteurisation was more effective for skinless chicken samples, compared to its skin-on counterparts.
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    Use of X-ray to identify contaminants in pelleted seed lots for biosecurity : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science (Agricultural Science) at Massey University, Manawatū, New Zealand
    (Massey University, 2019) Wang, Yufan
    Thousands of tonnes of seed, of which around 10% is pelleted, comes into New Zealand through international trade every year. However, this trade also brings potential risks to New Zealand biosecurity. Pelleted seeds can contain contaminants, including seeds other than the crop species in the seed lot and inert matter; both may cause negative effects on crop growth or bring pests and diseases. A reliable method is necessary to inspect seed lots for the contaminants. The conventional way to inspect for contaminants in pelleted seeds is to separate the seeds from pellets and inspect visually. However, this is a time consuming and potentially health damaging procedure. A faster and safer non-invasive inspection method is needed urgently. X-ray imaging systems have the potential to non-invasively identify contaminants in seed lots. 2-D X-ray was firstly applied in this research to determine if the system could separate non-target seeds such as weed seed from naked crop “target” seeds, since if 2-D X-ray cannot separate non-target seeds from naked target seeds, there is little chance to separate seeds that are pelleted. In this research, three target species were used. These were beet (Rapistrum, Ranunculus and spinach as contaminants), carrot (Polygonum, Chenopodium and Solanum as contaminants) and lettuce (Sonchus and Lapsana as contaminants), because of their high contamination rates in imported seed lots. Seed shape parameters: dimensions, form, circularity, roughness and intensity, were used to characterize seeds for further comparison. The results showed Ranunulus can be separated from beet by dimensions and intensity; Rapistrum can be separated by elongation, circularity and intensity; spinach was hard to separate from beet. In the carrot group, Chenopodium and Solanum can be separated from carrot by either dimensions, elongation or circularity, while Polygonum cannot be separated from Carrot. For contaminants in lettuce, Sonchus can be separated from lettuce by dimensions and intensity; Lapsana can be separated by elongation and circularity. However, all the separation above was based on mean values, seeds with extreme sizes would limit the effects of shape parameters in seed separation. Determining if pelleting seeds can also be separated using the same parameters was the next important step for determining if 2-D X-ray can be used for pelleted seed inspection. However, little literature can be found regarding specific pelleting materials and pelleting procedures, as they are held by the seed companies. Therefore, protocols for pelleting the relatively small numbers of pelleted seed for research are needed. During several trials on seed pelleting, Methocel™ and gypsum was identified as suitable pelleting materials. The vortex mixer was identified as the best equipment for pelleting using a one-by-one adding method, which was feasible for pelleting both tiny-seeds and small-quantities seeds. The seeds pelleted showed a uniform and well-rounded appearance. However, when applying the same 2-D X-ray for seed separation, the seed projections were hard to be extracted for further analysis, because of the poor differentiation between seeds and pellets. This research explored the potential of using 2-D X-ray to separate naked non-target seed from naked target seeds by seed shape parameters. The outcomes confirmed that the mean values of shape parameters can separate contaminants from target seeds, however at the extreme ends of the range seed parameters overlap will limit the value of the shape parameters. Pelleting seeds under laboratory conditions can also be realized by using vortex mixer as equipment and using Methocel™ and gypsum as pelleting materials. Nonetheless, 2-D X-ray was not a reliable tool to detect pelleted seeds, since it is hard to separate seed projections from pellets with images only from a top view. 3-D X-ray could potentially be applied in future research because of its higher resolution than 2-D X-ray. In addition, 3-D X-ray images enable analysts to analyze seeds from different angles other than one fixed angle, which makes the analysis free from image overlap problems. Although research on 3-D X-ray for seed separation is at its beginning, it is potentially useful for pelleted seed analysis.
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    Removal of Cronobacter sakazakii and Listeria monocytogenes biofilms using enzymes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Manawatū, New Zealand
    (Massey University, 2019) He, Yang
    C. sakazakii and L. monocytogenes are pathogens that may occur in dairy manufacturing plants with the potential cause serious diseases in neonates if dairy products containing these bacteria are consumed. Control of these pathogens is through cleaning with chemicals such as caustics and acids. Enzymes have been considered as alternative cleaning agent as they are more environmentally friendly compared with traditional chemical-based cleaning. However, the use of enzymes to remove biofilms of these pathogens has not been well studied. The objectives of this study were (1) to explore the biofilm formation of C. sakazakii and L. monocytogenes on hydrophilic and hydrophobic surfaces; (2) test the efficacy of α-amylase, proteases and endoglucanase on removal of these biofilms. The first part of this study focused on screening for the robust strains that can form strong biofilm in reconstituted infant milk formula using a microtiter plate assay and stainless steel coupons. The second part evaluated the efficacy of enzymes on the removal of biofilms by impedance detection and epifluorescence microscopy. The results showed that 12 of 14 strains of C. sakazakii strains and half of the L. monocytogenes strains formed strong biofilm. The ability to form biofilm varied with the origin of the isolates with clinical isolates of C. sakazakii and food isolates of L. monocytogenes forming strong biofilm on microtiter plates and stainless steel surfaces. For the evaluation of enzyme efficacy, the biofilms were treated with α-amylase, proteases and endoglucanase at 85°C, pH 3 for 15 min. The results from the microtiter plate assay based on the absorbance at 550 nm showed that the enzymes especially proteases and endoglucanase were effective in removing biofilms. The effectiveness of cleaning by enzymes demonstrated by plate counting and impedance detection was supported by epifluorescence microscopy results. In conclusion, these results demonstrated the efficacy of enzymes on removal of biofilms of C. sakazakii and L. monocytogenes. Compared with traditional method of cleaning, enzymes are more effective in removing extracellular polymeric substance of biofilms.
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    3D printing materials for large-scale insulation and support matrices : thesis by publications presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering, Massey University, Albany, New Zealand
    (Massey University, 2019) Harris, Muhammad
    Additive manufacturing (AM) techniques have promising applications in daily life due to their superiority over conventional manufacturing techniques in terms of complexity and ease of use. However, current applications of polymer-based 3D printing (3DP) are limited to small scale only due to the high cost of materials, print times, and physical sizes of the available machines. In addition, the applications of 3DP are yet to be explored for insulation of different large-scale mechanical structures. For example, milk vats are large structures with complex assemblies (like pipes, joints, couplings, valves, ladders, vessel doors) that requires insulation to store the milk at a low temperature of 6 °C as per the NZCP1 regulations in New Zealand. Generally, milk vats lack any kind of proper insulation around them and require additional cooling systems to keep the milk at a prescribed temperature. Any variations in the temperature can lead to deterioration in the quality of milk. Therefore, there exists a research gap that can not only help to solve an industrial issue but also can be a first step towards real large-scale 3DP applications that can potentially lead to many others in future. For example, pipe insulation, food storage tanks, chemical storage tanks, water treatment. This research explores new and inexpensive materials for large-scale 3DP. For this purpose, the current state of the 3DP materials is analyzed and based upon this analysis two distinct approaches are devised: 1) in-process approach to improve the mechanical properties of the existing materials like polylactic acid (PLA), and 2) modification of inexpensive materials (like materials used in injection, rotational, and blow moulding) to make them printable. In the first approach, by controlling the process parameters, mechanical properties are studied. While in the second approach, blends of high density polyethylene (HDPE) and polypropylene (PP) with different thermoplastics (acrylonitrile butadiene styrene, ABS and polylactic acid, PLA) are investigated to achieve printability. Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) are used to analyze the proposed materials. The overall objective of this research is to devise low-cost materials comparable to the conventional processes that are capable of providing good mechanical properties (tensile, compressive and flexural) along with high resistance to thermal, moisture, and soil degradation. The results present significant enhancement, up to 30%, in tensile strength of PLA through in-process heat treatment. However, the softness induced during printing above 70 °C directs to the second approach of developing the novel blends of HDPE and PP. In this regard, the research develops three novel blend materials: 1) PLA/HDPE, 2) ABS/HDPE, and 3) ABS/PP. These materials are compatibilized by a common compatibilizer, polyethylene graft maleic anhydride (PE-g-MAH). PLA/HDPE/PE-g-MAH provides highest tensile strength among all existing FDM blends (73.0 MPa) with superior resistance to thermal, moisture and soil degradation. ABS/HDPE and ABS/PP provide one of the highest mechanical properties (tensile, compressive, and flexural) in ABS based FDM blends with superior thermal resistance to six days aging. ii The chemical characterization of aforementioned novel FDM blends shows partial miscibility with sufficient signs of chemical grafting. The significant intermolecular interactions are noted in FTIR that shows the grafting through compatibilizer (PE-g-MAH). The DSC analysis shows visible enhancement in different thermal parameters like glass transition, melt crystallization and degradation along with signs of partial miscibility. Furthermore, TGA analysis confirms the partial miscibility along with the enhanced onset of degradation temperature. The increase in onset temperatures of each of the three blends proves the thermal stability to high temperatures. Hence, each of the developed blends is capable of resisting any material deterioration during routine cleaning operation at 70 °C of milk vats. This research has resulted in 5 journal publication (four published and one submitted), two conference proceedings and a number of posters presented at local conferences. This research is the part of food industry and enabling technologies (FIET) research program funded by the ministry of business, innovation and employment (MBIE), New Zealand in collaboration with Massey University, Auckland.
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    Plasma-arc cutting control : investigations into machine vision, modelling and cutting head kinematics : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Manawatu, New Zealand
    (Massey University, 2018) Flemmer, Mathew
    Plasma-arc cutting (PAC) is widely used in industry, but it is an under-researched fabrication tool. A review of the literature reveals much study is needed to improve the PAC process regarding efficiency, quality, stability and accuracy. This research investigated a novel control method for PAC. The PAC process was investigated to identify the gaps, and develop feasible methods, methodologies and systems to improve the PAC cutting quality and process control using machine vision. An automated, visual-inspection algorithm was successfully developed. The algorithm uses NC code to path plan and perform kerf width measurement. This visual inspection facilitated research into several aspects of PAC such as the extent of radiative heat transfer, the significance of kerf asymmetry, and a model describing the slope of the leading edge of the kerf-with respect to feed rate and material thickness. A kinematic investigation was conducted on 3 bevel capable plasma heads to complete the elements of a novel control method. An automated, visual-inspection (AVI) system for PAC was designed that consists of a vision unit and a mounting rig. This system is able to perform real-time, kerf width measurement reaching an accuracy of 0.1mm. The methodology was validated by experiment, testing cuts on parts with varying size, shape and complexity. The outcomes of this research were published in the International Journal of Mechanical and Production Engineering and the proceedings of the 2017 Mechatronics and Machine Vision in Practice (M2VIP) international conference. With this developed vision rig, further research was conducted such as an empirical investigation into the relationship between kerf angle and kerf width with respect to torch height, feed rate and material thickness. This investigation was comprised of 35 combinations of the process parameters with 9 replicates for each. A relationship between the process parameters and quality measures was developed, and the magnitudes of kerf asymmetries were quantified. The understanding of the phenomenology of PAC is deficient in several areas. An experimental study was undertaken that reduced the effects of heat transfer by conduction and convection in order to estimate the contribution by radiative heat transfer. This experimental study maintained an arc between a water-cooled anode and plasma torch for 15 seconds. A test piece was specifically designed with imbedded, resistance-temperature-device thermometers positioned around the transferred arc and the temperature was measured. This investigation was able to estimate the effects of radiation from the plasma-arc. The study found radiative heat transfer is less than 3% of the total power input. Another experimental study obtained information on the shape of the leading edge of the kerf. For this study slots were cut into steel plates of 6, 8 and 10mm thickness, at feed rates between 350 and 2000mm/min with a torch height of 1.5mm. Edge points for the centre axis of the leading profile were obtained. A relationship between surface angle and material thickness and feed rate was established and is validated through the test range. A study on obtaining cutting profile data on the front face of the kerf was also undertaken. Slots were cut into plates of 6 and 10mm thickness. Edge points were obtained for the front 180 degrees of the kerf face at sections in 2mm increments. A 3D representation of the shape of the face was then able to be presented. Finally, the kinematics for 3 bevel capable PAC heads was developed. Two of the heads are existing industrial heads, and the third head is being developed by Kerf Ltd. The kinematics investigation produced the DH parameters and transformation matrices for the forwards kinematics. These were validated using MATLAB®. The resulting dynamics were also produced. In conclusion, PAC is a complicated process. This research carried out several studies and has addressed several literature gaps with the proposed methods, methodologies and systems, developed through machine vision and PAC head kinematic study. This research was funded by Callaghan Innovation PhD research funding and received financial support from Kerf Ltd. Callaghan Innovation is a New Zealand government research funding body. Kerf Ltd. is a New Zealand PAC machine manufacturer and distributor.
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    Particle coating using foams and bubbles : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemical and Bioprocess Engineering at Massey University, Palmerston North, New Zealand
    (Massey University, 2017) Singh, Shakti
    This thesis investigates powder coating using foams or bubbles. The work initially started on foams. Wettability studies first showed that foams can be used to coat powders. Research then focussed on the fundamental unit of foams, the bubble. An experimental apparatus was designed and built to perform particle-bubble impact studies in air. Bubble solutions comprised of water, hydroxypropyl methylcellulose (HPMC) and sodium dodecyl sulphate (SDS). Four distinct physical behaviours occur when a particle impacts a bubble: (i) particle capture, (ii) particle slide-off, (iii) bubble burst and (iv) bubble self-healing. The rate processes that occur during particle-bubble impact are; (i), surface area creation by bubble film stretching; (ii), delivery of surface active molecules to the newly created surface; and (iii), stress dissipation as the film is stretched. The ability of the solutions to do (ii) and (iii) are highly complex relying on the thermodynamic equilibrium of the solutions and the local perturbations in the near surface region. Therefore, establishing quantitative boundaries of behaviour is a difficult exercise. It is proposed that, for solutions above the cac or cmc, (critical aggregate concentration, critical micelle concentration) where self-healing occurs, the rate of (ii) > rate of (i) and the rate of (iii) > rate of (i). For solutions below the cac, where bursting occurs, the opposite is true, the rate of (ii) < rate of (i) and the rate of (iii) < rate of (i). Intermediate behaviours such as slide-off of capture are within the range of self-healing behaviours, but where the energy of the particle is insufficient to penetrate the bubble. These behaviours are explained by complexation theory. For SDS concentration ≥ cac and cmc, small aggregates of SDS and HPMC locally supply surfactant to the surface of the stretching bubble film. This maintains low surface tension stress and self-healing results. For SDS concentrations < cac, self-healing occurs because the complexation is a HPMC-SDS sea containing SDS islands. The HPMC-SDS sea structure is sufficiently interlinked to simply stretch with the film, while the SDS islands de-aggregate quickly in the near surface region to supply the newly created surface with surfactant. Here the supply rate is faster than the stretching and so the new surface area is populated with SDS molecules. In contrast bursting occurs when the complexation is HPMC-SDS islands in a SDS sea. Here, the rapid film extension is so fast that the islands of HPMC-SDS become isolated and the film loses structural homogeneity. Furthermore, the rate of new surface creation is too fast for diffusion of SDS molecules from the bulk ‘sea’ to the newly created surface. This results in both an inhomogeneous structure and local increases in surface tension, causing both stress concentration in the film and the Marangoni effect. Extensional viscosity measurements, conducted in collaboration with Monash University, Australia, produced three behaviours as solutions were thinned: bead-on-string, blob and long-lived filaments. Solutions which produced long lived filaments here correspond to those that self-healed during particle impact (when the impact velocity was sufficient). It is proposed that this long-lived filament behaviour is due to the SDS concentration being > cmc, where the SDS micelles act like ‘ball-bearings’ between the extending HPMC chains. Coatings were characterised by SEM and gravimetric measurement. Cross-sectional imaging of the soft particle that penetrated self-healing bubbles were found to have a continuous coating layer around the particle. Surface topography of bubble coated particles were compared with classical droplet coated single particles from the literature. Bubble coated particles were found to be smoother than the droplet coated particle. The knowledge gained here was used to suggest how an industrial-scale particle coater using bubbles may be designed.
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    Purification and characterisation of a secreted glycosidase, from the extreme xerophile Wallemia ichthyophaga : a thesis presented in partial fulfilment of the requirement for the degree in Master of Science in Biochemistry at Massey University Palmerston North, New Zealand
    (Massey University, 2014) Miller, Taryn Angela
    With recent pressure to reduce the environmental impact of leather production, research has been focused on the development of an alternative depilation method, as the conventional method for depilation contributes up to 60% of the total pollution produced. Contaminated salted ovine pelts stored at LASRA were easily depilated when drum washed, and the resultant leather was of good quality. The pelts were visibly contaminated with microorganisms, and it was thought that these may be secreting enzymes that loosened the wool fibre without damaging key structural skin components. Identification of the enzyme or enzymes was thus of interest. The microorganism/s responsible for the secretion of the depilation enzyme/s were isolated and identified through sequencing the 16S/18S ribosomal RNA genes. Depilation, using the crude secretome solutions, was then assessed using fresh ovine skin as well as SACPIC, a micro scale staining method used to assess skin structure. Unfortunately, none of the secretomes from either a single or a combination of the microorganisms isolated, had depilation activity. The secretome of W.ichthyophaga, a xerophilic filamentous fungus, which was consistently isolated from the contaminated pelts, was chosen to be characterised using proteomic methods. 1D SDS-PAGE gel/CHIP separation of the proteins in the secretome showed it contained mainly glycosidases, with no lipases, esterases, or proteases identified. Some of the proteins identified had suggested roles in resistance to osmotic pressure, while the remaining proteins were intracellular. Overall, 21 proteins were identified. A purification procedure involving AEX and SEC was successfully developed for the isolation of one of the glycosidases from the secretome. The resultant purified fractions formed a doublet band when analysed by SDS-PAGE. The reason for this remains unknown, but was shown not to be due to an impurity or heterodimerisation. The purified glycosidase was identifed as belonging to the GH3 family by mass spectrometry. It was found to have a pH optimum of pH 6.0, was optimally active at 10% NaCl, and was itself glycosylated. The glycosidase was able to hydrolyse both a- and ß- linked glycosidic bonds in di- and polysaccharides. Interestingly, both the disaccharide and artifical p-nitrophenol forms of galactose were not cleaved by the enzyme.