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A study of solid and protein extraction in tofu production

  • Authors: Yuwono, Sudarminto
  • Date: 1998
  • Type: Text , Thesis , Masters
  • Full Text: false
  • Description: "The aim of this study was to investigate the extraction process, in particular the effects of solid and protein extractability in tofu production and their effects on tofu quality in terms of physical, chemical and sensory characteristics."
  • Description: Master of Applied Science (Food Technology)

A study of sulphur xanthates in relation to their role in froth flotation of sulphide minerals

  • Authors: Honeyman, Ronald
  • Date: 1980
  • Type: Text , Thesis , Masters
  • Full Text: false
  • Description: Potassium alkyl xanthates are commonly used as collectors in the flotation of sulphide minerals. Much research has been directed to the formulation of mechanisms responsible for the hydrophobicity of the sulphide minerals in xanthate flotation. Alkyl dixanthogen plays an important role in this mixed-potential mechanism, and is regarded as the species which imparts hydrophobicity to the mineral surface. Winter has recently suggested that sulphur xanthates, which are chemically very similar to alkyl dixanthogen, may play a significant role in the processes rendering the sulphide minerals hydrophobic during froth flotation. The aim of this investigation was to develop techniques for the separation and identification of sulphur xanthates at very low levels of conecentration. Techniques employed were Molecular Emission Cavity Analysis Spectroscopy and High Performance Liquid Chromatography. It was possible to extract the sulpur xanthates from simulated flotation liquors, separate the individual species, and determine them to a level of 0.05 ppm in the liquor. Aklyl sulphur dixanthates were found to disproportionate in methanol solution.
  • Description: Masters Degree in Applied Science

A study of visitor satisfaction in tourism enterprises

  • Authors: Ali, Shameen
  • Date: 2012
  • Type: Text , Thesis , DBA
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  • Description: Satisfying customers is fundamental to the marketing concept and has long been recognised as important, firstly in the economic discipline and subsequently in marketing and in business generally. In a competitive marketplace customer satisfaction is closely linked to the ability of the organisation to deliver quality. Therefore, organisations rely on the feedback received from customers about how satisfied or dissatisfied they are with product and service provision and their perceptions of the value received. The study examines the various product and service attributes that contribute to visitor satisfaction and experience, and evaluates the role of price-value perceptions and behavioural intentions. This examination was undertaken by the study of three tourism enterprises operating in the heritage tourism area. These included Sovereign Hill, which is an historic goldfields township; Brambuk, which is an indigenous cultural centre located in the Grampians in Western Victoria; and Werribee Mansion, which depicts the life of a wealthy farming family in the early periods in Victoria. This study has provided insight into the understanding of visitor satisfaction in tourism enterprises by evaluating the relationship between overall satisfaction and dissatisfaction and how these influence revisit and recommending behaviour, as well as the influence of price-value perceptions on satisfaction, experience and enjoyment. The study shows that price-value dissatisfaction impacts negatively on the willingness of visitors to recommend a tourism venue to others and that price dissatisfaction tends to impact negatively on satisfaction. The results provide some insight into what contributes to tourist satisfaction, enjoyment and experience. The findings are expected to assist strategic and operational managers in their quest for continued quality enhancement and the provision and renewal of tourism products and services. It is expected that the findings will provide some guidance to managers, tourism operators, marketers and researchers alike in developing well informed data and analyses that are the key to strategic and competitive advantage.
  • Description: Doctor of Business Adminstration

A three tier forensic model for automatic identification of evidence of child exploitation by analysing the content of chat-logs

  • Authors: Miah, Md Waliur Rahman
  • Date: 2016
  • Type: Text , Thesis , PhD
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  • Description: Detection of child exploitation (CE) in Internet chatting by locating evidence in the chat-log is an important issue for the protection of children from prospective online paedophiles. The un-grammatical and informal nature of chat-text makes it difficult for existing formal language processing techniques to handle the problem. The methodology of the current research avoids those difficulties by developing a multi-tier digital forensic model bulit on new ideas of psychological similarity measures and ways of applying them to chat-texts. The model uses text classifiers in the beginning to identify shallow evidence of CE. For locating the particular evidence it is required to identify the behavioural pattern of CE chats consisting of documented CE psychological stages and associate the perpetrators' posts to them. Similarities among the posts of a chat play an important role for the task of differentiating and identifying these stages. To accomplish this task a novel similarity measure is constructed backed by a dictionary with terms associated with each CE stage. Using the new similarity measure is constructed backed by a dictionary with terms associated with each CE stage. Using the new similarity measure in a hieraarchial agglomerative algoritm a new clusterer is built to cluster the posts of a chat-log into the CE stages to learn whether it follows the CE pattern. Inspired by the field of recognition of textual entailment a new soft entailment technique is developed and implemented to locate the specific posts associated with the CE stages. Those specific posts of the perpetrator are extarcted as the particular evidence from the chat-log. It is anticipated that the developed methodology will have many future pratical implementations. It would assist in the development of forensic tools for digital forensic experts in law and enforcement agencies to conveniently locate evidence of online child grooming in a confiscated hard disk drive. Another future implementation would be a parental filter used by parents to protect their children from potential online offenders.
  • Description: Doctor of Philosphy

Abnormalities in T cell lineages from patients with Langerhans cell histiocytosis

  • Authors: Mitchell, Jenée
  • Date: 2018
  • Type: Text , Thesis , PhD
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  • Description: Langerhans cell histiocytosis (LCH) is a rare inflammatory disease characterised by lesions containing CD1a+ myeloid lineage ‘LCH’ cells. Other immune cells such as T cells are also present within LCH lesions and the cytokine milieu suggests T cell activation. T cells have an established role in regulating cellular immunity and there is already evidence that multiple T cell lineages are enriched in LCH lesions, implying that they may have a role in LCH pathogenesis. Foxp3+ regulatory T cells (Tregs) and the immune suppressive cytokine, transforming growth factor beta (TGF-
  • Description: Doctor of Philosophy

About regularity properties in variational analysis and applications in optimization

  • Authors: Nguyen, Hieu Thao
  • Date: 2015
  • Type: Text , Thesis , PhD
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  • Description: Regularity properties lie at the core of variational analysis because of their importance for stability analysis of optimization and variational problems, constraint qualications, qualication conditions in coderivative and subdierential calculus and convergence analysis of numerical algorithms. The thesis is devoted to investigation of several research questions related to regularity properties in variational analysis and their applications in convergence analysis and optimization. Following the works by Kruger, we examine several useful regularity properties of collections of sets in both linear and Holder-type settings and establish their characterizations and relationships to regularity properties of set-valued mappings. Following the recent publications by Lewis, Luke, Malick (2009), Drusvyatskiy, Ioe, Lewis (2014) and some others, we study application of the uniform regularity and related properties of collections of sets to alternating projections for solving nonconvex feasibility problems and compare existing results on this topic. Motivated by Ioe (2000) and his subsequent publications, we use the classical iteration scheme going back to Banach, Schauder, Lyusternik and Graves to establish criteria for regularity properties of set-valued mappings and compare this approach with the one based on the Ekeland variational principle. Finally, following the recent works by Khanh et al. on stability analysis for optimization related problems, we investigate calmness of set-valued solution mappings of variational problems.
  • Description: Doctor of Philosophy
  • Description: Regularity properties lie at the core of variational analysis because of their importance for stability analysis of optimization and variational problems, constraint qualications, qualication conditions in coderivative and subdierential calculus and convergence analysis of numerical algorithms. The thesis is devoted to investigation of several research questions related to regularity properties in variational analysis and their applications in convergence analysis and optimization. Following the works by Kruger, we examine several useful regularity properties of collections of sets in both linear and H

Access and engagement of First Nations women in maternal and child health services

  • Authors: Austin, Catherine
  • Date: 2023
  • Type: Text , Thesis , PhD
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  • Description: This thesis explores and describes the engagement of First Nations women, with children from birth to five years of age, with Maternal and Child Health (MCH) services in Victoria, Australia. Identification of the factors that facilitate, support or hinder these women’s engagement with MCH services could strengthen the model of care to effectively engage First Nations women with these services. Access in the early years of a child’s life to integrated, effective, community-based services is a well-established predictor of a child’s successful transition to school and their lifelong education and employment outcomes. Such access is crucial in a child’s first 2,000 days (the period from conception to the child’s fifth year), which forms the foundation for a child’s lifetime development and health. Prior evaluative studies have shown that participation in MCH services in Victoria improves the health outcomes for children and families, particularly First Nations families. However, First Nations women and their children in Victoria show poorer health outcomes and lower participation in MCH services compared to non-Indigenous persons; this suggests a need to improve the current Victorian MCH service model. This thesis contributes recommendations for such improvements. The literature review (Chapter 2) identified the absence of a synthesis of qualitative studies of models of care to help guide MCH practice and innovation for all families, especially those at risk of child abuse and neglect. To address this gap, a three-phase qualitative study was conducted in the Glenelg Shire, Victoria, Australia, using narrative inquiry integrated with the Indigenous philosophy ‘Dadirri’. ‘Dadirri’, which emphasises deep and respectful listening, guided the development of the research design; this methodology assisted in understanding Indigenous culture and its sensitivities, building trust with the First Nations peoples involved in the studies, developing open-ended and conversational dialogue, and building respectful relationships. This method enabled First Nations women’s voices to be heard and the collection of rich data based on participants’ perspectives of and experiences with MCH services in Victoria. Study One (Chapter 4) recruited First Nations women residing in the Glenelg Shire, with at least one child aged birth to five years, to explore their perceptions and experiences of MCH services and barriers to accessing and engaging with MCH services. Study Two (Chapter 5) compared Study One data with accounts from MCH nurses working in Glenelg Shire. Study Three (Chapter 6) reviewed a piloting of the Early Assessment Referral Links (EARL) concept (developed by the researcher) that aims to improve First Nations women and their children’s access to and engagement with MCH services. EARL involved the core principles of narrative inquiry integrated with ‘Dadirri’. Study One and Two found that enabling factors for access and engagement include interventions that are culturally sensitive and effective; recognise the social determinates of health (SDOH) and social and emotional wellbeing; are timely, appropriate, culturally strong, flexible, holistic and community-based; support continuity of care and communication; and encourage early identification of risk, particularly of family violence (FV), and further assessment, intervention, referral and support in the child’s first 2,000 days. Barriers to access and engagement include an ineffective service model built on mistrust, poor communication due to cultural differences between client and provider (particularly around identification and disclosure of woman’s risk of FV), lack of continuity of care between services, limited flexibility of service delivery to suit individual needs, and a service model that does not recognise the importance of the SDOH and social and emotional wellbeing. Study Three results showed that participation of First Nations families in MCH services was consistently above the state average during the pilot period, and several First Nations families were referred to EARL stakeholders and other health professionals during the pilot. Further, there were increases in First Nations children being breastfed, fully immunised and attending Early Start Kindergarten, and identification of First Nations children at risk of abuse or neglect improved (with a significant increase in referrals for FV and child protection and significant decrease in episodes of out-of-home care). This thesis’s findings can support policy development. This research shows that timely, effective, holistic engagement with First Nations women in their child’s first 2,000 days, that respects their culture and facilitates genuine partnerships built on co-design and shared decision-making with the Indigenous community, needs to be an essential part of the MCH service model. Additionally, this thesis recommends adopting a strengths-based approach that respects First Nations peoples’ child-rearing practices and culture, and providing necessary training to MCH nurses who work with First Nations families. Keywords: child family health, continuity of care, First Nations women
  • Description: Doctor of Philosophy

Accounting and Slavery: the case of Companhia Geral do Grão Pará e Maranhão (1755-1778)

  • Authors: Pinto, Ofelia
  • Date: 2014
  • Type: Text , Thesis , PhD
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  • Description: Contrary to the traditional view of accounting as a neutral technical practice, recent studies have increasingly viewed this technology as being social and institutional in both its orientation and effects. An important outcome of these portrayals of accounting’s decisive influence within organisations and broader contexts has been to highlight the enabling role it has played within significant historical events. This has included exploration of what has been termed the “dark side” of accounting: abhorrent episodes from human history in which accounting has been implicated. Slavery is one such episode. Adopting the conception of accounting as a social and institutional practice, this interpretative historical study applies the concept of “action at a distance” and previous literature on the interrelations between accounting and the state as a conceptual framework to critically analyse the accounting practices that were developed and adopted by the Companhia Geral do Grão Pará e Maranhão, a Portuguese company established primarily for the purpose of trading in human beings (slaves) in the second half of the 18th century. As well as providing a novel addition to the literature dealing with the “dark side” of accounting, this archive-based case study also sheds further light on accounting’s potential to act as a powerful agent of social change, including its facilitation of episodes of human misery.
  • Description: Doctor of Philsophy

Accurate and efficient clustering algorithms for very large data sets

  • Authors: Quddus, Syed
  • Date: 2017
  • Type: Text , Thesis , PhD
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  • Description: The ability to mine and extract useful information from large data sets is a common concern for organizations. Data over the internet is rapidly increasing and the importance of development of new approaches to collect, store and mine large amounts of data is significantly increasing. Clustering is one of the main tasks in data mining. Many clustering algorithms have been proposed but there are still clustering problems that have not been addressed in depth especially the clustering problems in large data sets. Clustering in large data sets is important in many applications and such applications include network intrusion detection systems, fraud detection in banking systems, air traffic control, web logs, sensor networks, social networks and bioinformatics. Data sets in these applications contain from hundreds of thousands to hundreds of millions of data points and they may contain hundreds or thousands of attributes. Recent developments in computer hardware allows to store in random access memory and repeatedly read data sets with hundreds of thousands and even millions of data points. This makes possible the use of existing clustering algorithms in such data sets. However, these algorithms require a prohibitively large CPU time and fail to produce an accurate solution. Therefore, it is important to develop clustering algorithms which are accurate and can provide real time clustering in such data sets. This is especially important in a big data era. The aim of this PhD study is to develop accurate and real time algorithms for clustering in very large data sets containing hundreds of thousands and millions of data points. Such algorithms are developed based on the combination of heuristic algorithms with the incremental approach. These algorithms also involve a special procedure to identify dense areas in a data set and compute a subset most informative representative data points in order to decrease the size of a data set. It is the aim of this PhD study to develop the center-based clustering algorithms. The success of these algorithms strongly depends on the choice of starting cluster centers. Different procedures are proposed to generate such centers. Special procedures are designed to identify the most promising starting cluster centers and to restrict their number. New clustering algorithms are evaluated using large data sets available in public domains. Their results will be compared with those obtained using several existing center-based clustering algorithms.
  • Description: Doctor of Philosophy

Accurate prediction of sewer network flows and assessment of groundwater infiltration volumes in sewer networks

  • Authors: Jayasooriya, Mahinda
  • Date: 2022
  • Type: Text , Thesis , PhD
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  • Description: Excessive flows due to inflow and infiltration (I&I) in sewer networks contribute to hydraulically overloaded sanitary sewer networks. Understanding the cause–effect relationships associated with sewer network flow generation and accurate quantification of excessive flow volumes entering sewer networks is crucial to developing solutions to resolve this issue. A systematic literature review found a gap in understanding the cause–effect relationships of I&I and no universally accepted method for I&I estimation. This research used three years of data from an Australian sewer catchment in Ballarat, Victoria, as a case study to enhance understanding of the network flow generation process. The aims of this research were to accurately predict sewer network flows, reliably separate the groundwater infiltration (GWI) volume of sewer network flow, improve understanding of associated processes and identify the influential parameters that impact sewer network flow. This research used three methods to achieve these aims. First, commercially available software was used to develop and calibrate a sewer network model to predict flows with data from the case study catchment. The best practice guidelines available in Australia were used to calibrate the model, and a new method was introduced to separate the sewer network flow components. Second, two classical hydrology applications, the recursive filter and the flow duration curve (FDC) methods, were used to separate the GWI component of the total sewer network flow and understand the performance of the sewer catchments. Third, an artificial neural network (ANN) model was developed to predict sewer network flow. Parameters known to influence sewer flows were incrementally introduced to the ANN model to improve performance and understand their relative importance. This study finds that commercially available software can predict total sewer network flows with reasonable accuracy using the Wallingford or triangular hydrograph (RTK) hydrological implementation methods. However, the software cannot replicate the dynamic nature of the complex I&I processes that occur over time or reliably separate the sewer network flow components. A key finding from this study is that commercially available software has clear limitations in separating sewer network flow components. Recursive filter and FDC methods can be successfully used as standalone techniques to calculate the GWI volume. These methods have further value in comparing the I&I between catchments to determine flow characteristics and are straightforward for practising engineers to use. The ANN model predicts sewer flow with a high level of accuracy, and soil moisture is the most critical predictor of the total flow regime. The ANN model is also able to predict the dynamic and complex nature of I&I into sewer networks. More research is needed to achieve effective and reliable separation of individual components in an overall sewer flow regime. ANN and other emerging machine learning techniques show much potential to effectively predict sewer flows across a range of sewer network and catchment characteristics.
  • Description: Doctor of Philosophy

Action research and occupational health and safety: an exploratory study

  • Authors: Runnalls, John
  • Date: 2000
  • Type: Text , Thesis , Masters
  • Full Text: false
  • Description: "This paper describes an exploratory study into action research and its potential application within the field of Occuptional Health and Safety (OHS) in Australia."
  • Description: Master of Applied Science

Acute cardiovascular responses during post-exercise recovery to short-term exhaustive exercise

  • Authors: Zichy-Woinarski, Christopher
  • Date: 2000
  • Type: Text , Thesis , Masters
  • Full Text: false
  • Description: "The aim of this study was to examine the effect of consecutive bouts of acute exhaustive exercise in a hot ambient environmemt on baroreflex gain, plasma volume and heart variability one week post-exercise in trained individuals." Problem with pages xviii-xx Pages 9-37 missing.
  • Description: Masters of Applied Science

Adapting port cluster theory to contextualise the remarkable rise of the gold rushes port of Melbourne: 1851–1861

  • Authors: Taylor, Peter
  • Date: 2022
  • Type: Text , Thesis , PhD
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  • Description: The research question that forms the basis of this thesis asks how and what drove the port of Melbourne to advance 30–50 years growth in less than ten during the 1850s gold era. To answer this question this thesis modifies and tests a new methodological approach to read the port’s growth driven by a close reading and evaluation of port cluster theory. Developed in the early 2000s the theory synthesises elements that constitute a port and operations through a wide range of components and activities. Recognising that a twenty-first-century port is not the same as a mid-nineteenth-century port, through advances brought on by a wide range of modern technologies, the theory has been historicised to dismantle the 1851–1861 gold era port of Melbourne to recognise its parts and how it was built. One of the tools to be enhanced and expanded for this is the cluster table of components and activities, providing specifics for activities undertaken at a mid-nineteenth-century port. A key constituent this propels the research forward when applied at Melbourne’s four ports of central Melbourne, Sandridge (Port Melbourne), Williamstown, Footscray and the Saltwater (Maribyrnong) River (combined). The argument is made that the ports evolved to be a port cluster reinforced by the exploration of specific themes of defence, security, river punts, entrepreneurs, ballast trade, quarrying, railways, noxious industries, shipwreck salvage, shipbuilding, ship repairs, tourism and wharf construction as topics. This thesis then uses the evidence gained to claim that the port did indeed evolve into a cluster port by 1861. The wider implication of this research is that a new framework exists for understanding the complexities of a mid-nineteenth-century port and how this can be done in a systematic way. For this methodology to demonstrate utility outside the port of Melbourne, requires further testing at sites within Australia, and worldwide, for confirmation of universality.
  • Description: Doctor of Philosophy

Addressing specific individual learning needs

  • Authors: Kuzmich, Karolina
  • Date: 1998
  • Type: Text , Thesis , Masters
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  • Description: Master of Education

Adolescents and the extended residential learning program : A case study

  • Authors: McDonough, Sharon
  • Date: 2002
  • Type: Text , Thesis , Masters
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  • Description: The purpose of this study was to explore, through the use of a case study, the impact of an eight-week residential learning program upon self-concept, learning and understanding of community amongst adolescent participants. The study utilized multiple methods of data collection including interviews, focus groups, observation, the Learning Process Questionnaire and the Self-Description Questionnaire II in order to address the research question.
  • Description: Master of Education (Research)

Adventures in software engineering : plugging HCI & acessibility gaps with open source solutions

  • Authors: Lansley, Alastair
  • Date: 2020
  • Type: Text , Thesis , PhD
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  • Description: There has been a great deal of research undertaken in the field of Human-Computer Interfaces (HCI), input devices, and output modalities in recent years. From touch-based and voice control input mechanisms such as those found on modern smart-devices to the use of touch-free input through video-stream/image analysis (including depth streams and skeletal mapping) and the inclusion of gaze tracking, head tracking, virtual reality and beyond - the availability and variety of these I/O (Input/Output) mechanisms has increased tremendously and progressed both into our living rooms and into our lives in general. With regard to modern desktop computers and videogame consoles, at present many of these technologies are at a relatively immature stage of development - their use often limited to simple adjuncts to the staple input mechanisms of mouse, keyboard, or joystick / joypad inputs. In effect, we have these new input devices - but we're not quite sure how best to use them yet; that is, where their various strengths and weaknesses lie, and how or if they can be used to conveniently and reliably drive or augment applications in our everyday lives. In addition, much of this technology is provided by proprietary hardware and software, providing limited options for customisation or adaptation to better meet the needs of specific users. Therefore, this project investigated the development of open source software solutions to address various aspects of innovative user I/O in a flexible manner. Towards this end, a number of original software applications have been developed which incorporate functionality aimed at enhancing the current state of the art in these areas and making that software freely available for use by any who may find it beneficial.
  • Description: Doctor of Philosophy

Advocates or corporates : constructions of clinical nursing practice in Australia with regards to the idealisation of advocacy and autonomy

  • Authors: Cole, Clare
  • Date: 2019
  • Type: Text , Thesis , PhD
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  • Description: Although the idealisation of nurses as advocates is popularised in nursing literature and supported within nursing frameworks, codes and standards, there has been little critical examination of these ideas within contemporary Australian healthcare settings and nursing practice. The Australian Healthcare system is a complicated system of interacting service providers and consumers. Institutions that regulate healthcare professionals and organisations normalise understandings of nursing and nursing practice, including conceptualisations of the importance of autonomy and advocacy and how each is to be supported and/or practised. This study used the perceptions of practising Registered Nurses (RNs) to examine the actualities of advocacy and support for autonomy as they are carried out within clinical practice, and to highlight, problematise and then analyse differences between the rhetoric and realities of practice. Firstly, a phenomenological lens, including an ethnographic model of observation, was used to thematically map and examine the RNs’ lived experience of their practice, paying particular attention to their conceptions of and responsibilities toward advocacy and autonomy. This thematic analysis brought to the fore a range of assumptions that, although clearly normative within nursing practice, are in evident tension with one other. These were then re-examined using a range of Michel Foucault’s concepts concerning the construction and maintenance of regimes of truth. Designed to unpack the operations of power and knowledge, and to make visible the techniques of disciplinarity and governmentality that inform and support them, an engagement of these concepts has allowed this thesis to critically examine the normative constructions and enactments of nursing practice with regards to ideas and practices concerning advocacy and autonomy. What this thesis provides is a detailed examination of the contrasting constructions of power and knowledge within nursing practice in relation to advocacy and autonomy, how and why these concepts have been operationalised within nursing practice, and how they could be re-visioned into the future.
  • Description: Doctor of Philosophy

Age estimation and illicit image detection using a stochastic vision model

  • Authors: Islam, Mofakharul
  • Date: 2013
  • Type: Text , Thesis , PhD
  • Full Text: false
  • Description: The main objective of this research is to investigate and implement a robust approach with a view to provide the Law Enforcement Agencies (LEAs) with a dedicated forensic tool in future for inspecting confiscated PCs from the suspected paedophile to detect pedophilic images automatically and prevent children viewing pornographic and age-inappropriate images at their home and school and adults at their workplace while they are on the Internet. To achieve this goal, we use a novel face descriptor to differentiate child face from adult face based on categorical age specific contextual cues that are based on new knowledge in terms of features or contexts representatives of child and adult face. Given that the craniofacial cues contain enough structural information on visual cues on human face encoded in the form of high level features we can categorize age into adult and children in tandem with low level features. Finally, we will present a novel stochastic vision model based on Markov Random Fields (MRF) prior, which learned the pornographic contextual constraints from the training pornographic images and eventually introduce knowledge on pornography into our proposed stochastic classifier allowing classification of images into pornographic or benign.
  • Description: Doctor of Philosophy

Ageing under the rainbow : The interrelations between age, sense of belonging, and mental health among Australian gay men

  • Authors: Morris, Simon
  • Date: 2010
  • Type: Text , Thesis , PhD
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  • Description: This research investigated the interrelations between gay men’s age, sense of belonging (to the general community, the broader gay community, gay groups and with gay friends) and mental health by testing four models: direct, mediation, additive and moderation.
  • Description: Doctor of Psychology (Clinical)

Agoraphilic navigation algorithm in dynamic environment

  • Authors: Hewawasam, Hasitha
  • Date: 2021
  • Type: Text , Thesis , PhD
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  • Description: This thesis presents a novel Agoraphilic (free space attraction [FSA])-based navigation algorithm. This new algorithm is capable of undertaking local path planning for robot navigation in static and dynamic environments with the presence of a moving goal. The proposed algorithm eliminates the common weaknesses of the existing navigation approaches when operating in unknown dynamic environments while using the modified Agoraphilic concept. The Agoraphilic Navigation Algorithm in Dynamic Environment (ANADE) presented in this thesis does not look for obstacles (problems) to avoid; rather, it looks for free space (solutions) to follow. Therefore, this algorithm is also a human-like optimistic navigation algorithm. The proposed algorithm creates a set of Free Space Forces (FSFs) based on the current and future growing free space around the robot. These Free Space Forces are focused towards the current and future locations of a moving goal and finally generate a single attractive force. This attractive force pulls the robot through current free space towards the future growing free space leading to the goal. The new free space concept allows the ANADE to overcome many common problems of navigation algorithms. Several versions of the ANADE have been developed throughout this research to overcome the main limitation of the original Agoraphilic algorithm and address the common weaknesses of the existing navigation approaches. The ANADE I uses an object tracking method to identify the states (locations) of moving objects accurately. The ANADE II uses a dynamic obstacle prediction methodology to identify the robot’s future environments. In the ANADE III, a novel controller based on fuzzy logic was developed and combined with the new FSA concept to provide optimal navigational solutions at a low computational cost. In the ANADE III, the effectiveness of the ANADE II was further improved by incorporating the velocity vectors of the moving objects into decision-making. In the ANADE IV, a self-tuning system was successfully applied to the ANADE III to take advantage of the performances of free space attraction-based navigation algorithms. The proposed final version of the algorithm (ANADE V) comprises nine main modules. These modules are repeatedly used to create the robot’s driving force, which pulls the robot towards the goal (moving or static). An obstacle tracking module is used to identify the time-varying free spaces by tracking the moving objects. Further, a tracking system is also used to track the moving goal. The capacity of the ANADE was strengthened further by obstacle and goal path prediction modules. Future location prediction allowed the algorithm to make decisions by considering future environments around the robot. This is further supported by a self-tuning, machine learning–based controller designed to efficiently account for the inherent high uncertainties in the robot’s operational environment at a reduced computational cost. Experimental and simulation-based tests were conducted under dynamic environments to validate the algorithm. Further, the ANADE was benchmarked against other recently developed navigation algorithms. Those tests were focused on the behaviour of the algorithm under challenging environments with moving and static obstacles and goals. Further, the test results demonstrate that the ANADE is successful in navigating robots under unknown, dynamically cluttered environments.
  • Description: Doctor of Philosophy