title: Speed control of small motors through the Ćuk Converter Topology

authors: Hutchins, Michael

subjects: motor speed control

abstract: The Ćuk Converter offers simultaneous buck-boost operation, but requires careful design owing to its having a fourth-order transfer function and numerous practical design constraints. We exploit a serendipitous overlap between the converter circuit and the equivalent circuit of a dc motor to design a motor controller that can operate with supply voltage that is lower than the motor full-speed requirement. We examine the transfer function when such a topology is used to control the speed of a small motor. We conclude that the approach is relatively straightforward owing to the impact of the motor’s inductance. Measurements agree with theory.

text: Speed control of small motors through the Ćuk Converter Topology The Ćuk Converter offers simultaneous buck-boost operation, but requires careful design owing to its having a fourth-order transfer function and numerous practical design constraints. We exploit a serendipitous overlap between the converter circuit and the equivalent circuit of a dc motor to design a motor controller that can operate with supply voltage that is lower than the motor full-speed requirement. We examine the transfer function when such a topology is used to control the speed of a small motor. We conclude that the approach is relatively straightforward owing to the impact of the motor’s inductance. Measurements agree with theory.

year: 2016

title: Kumukumu 1, a hilltop site in the Aird Hills: Implications for occupational trends and dynamics in the Kikori River delta, south coast of Papua New Guinea

authors: David, Bruno O.

abstract: We report on archaeological excavations undertaken at Kumukumu 1 atop the dense rainforest-clad Aird Hills of the Kikori river delta islands, south coast of Papua New Guinea. Results indicate exploitation of the nearby environment, including the gathering of some 200 million shellfish from riverine habitats at the base of the hill some 600 years ago, and deposition of shell remains onto hilltop middens. We ask what the implications of such a site in a defensive location on the upper, steep hillslope of Kumukumu hill are for regional occupation and dynamics. We conclude that the hinterland-marine fringe islands of the river deltas that include the site of Kumukumu 1 were especially sensitive to heightened cross-cultural influences and inter-group raids and competition, leading to accelerated processes of centralisation and aggrandisement among some groups, and the subjugation, fragmentation and dispersal of less powerful neighbouring groups.

text: Kumukumu 1, a hilltop site in the Aird Hills: Implications for occupational trends and dynamics in the Kikori River delta, south coast of Papua New Guinea We report on archaeological excavations undertaken at Kumukumu 1 atop the dense rainforest-clad Aird Hills of the Kikori river delta islands, south coast of Papua New Guinea. Results indicate exploitation of the nearby environment, including the gathering of some 200 million shellfish from riverine habitats at the base of the hill some 600 years ago, and deposition of shell remains onto hilltop middens. We ask what the implications of such a site in a defensive location on the upper, steep hillslope of Kumukumu hill are for regional occupation and dynamics. We conclude that the hinterland-marine fringe islands of the river deltas that include the site of Kumukumu 1 were especially sensitive to heightened cross-cultural influences and inter-group raids and competition, leading to accelerated processes of centralisation and aggrandisement among some groups, and the subjugation, fragmentation and dispersal of less powerful neighbouring groups.

year: 2015-01-01

title: Making the invisible visible: Exploring the complex pathways between childhood experiences of maltreatment and the perpetration of family harm

authors: Dempster-Rivett, Kirsty

subjects: Childhood maltreatment

abstract: Preventing family harm and providing care for those affected is a high priority for governments and social services worldwide. Adverse consequences of family harm continue to place demands on justice, mental health and care and protection services. The costs to individuals, families and communities are beyond measure, given that rates of family harm are under-reported. Quantitative researchers have demonstrated a link between childhood maltreatment and family harm perpetration with existing psychological theories used to explain this link. However, mainstream theories were first developed many decades ago, at a time when the notion of gender was not inclusively factored into theory development. Neither were they developed with or by Indigenous peoples, calling into question the translatability of mainstream theories for stopping the intergenerational transmission of trauma and violence. 
The main aim of this thesis was to explore the relationship between childhood maltreatment and the perpetration of family harm by investigating two research questions. How could psychological theories better explain the pathways between childhood experiences of maltreatment and family harm perpetration? And, to what extent do psychological theories about the cycle of family harm reflect the experiences of Māori and non-Māori men and women in Aotearoa New Zealand? To answer these questions, interviews were conducted with 16 individuals who self-identified as perpetrating family harm and had childhood histories of maltreatment. (n=8 men, n=8 women). Purposive sampling ensured an equal number of Māori (Indigenous people of Aotearoa New Zealand) and non-Māori participated in the research. Thematic analysis was utilised to examine the personal conceptualisations regarding the association between experiences of childhood maltreatment and subsequent perpetration of family harm. The core corpus of data explored the maltreatment-family harm relationship within and between Māori and non-Māori men and women. This thesis is comprised of three studies that investigate the intergenerational transmission of trauma and violence.

The first study analysed the interviews of the seven participants removed from their families of origin as children. All described ongoing experiences of poly-victimisation in subsequent placements, whether through adoption, foster or residential settings. When examined alongside all women interviewed in this thesis, men more often reported that their childhood maltreatment was overlooked by professionals. The findings of this study highlighted a relationship between the perpetration of family harm and limited relational and emotional experiences during childhood. Intervention points across the life span were identified to stop the intergenerational transmission of trauma and violence for people removed from their family of origin as children.

The second study focused on the experiences of the eight Māori men and women interviewed. A culture of silence surrounding childhood maltreatment pervaded all interviewees’ childhood experiences. However, additional issues, including cultural isolation, were evident for Māori from the adults and professionals charged with their care. Māori interviewees identified three core Indigenous concepts that facilitated healing and intergenerational wellbeing: Wairua (spiritual connection), Pou (becoming a symbol of strength and support for self and others), and Tūrangawaewae (finding a sense of belonging). A return to Indigenous knowledge and practices was integral to stopping the intergenerational transmission of trauma and violence. This highlights the importance of privileging Indigenous knowledge in existing theoretical understanding of the cycle of family harm and incorporation in prevention initiatives.

The final study explored the impact of psychological distress within the cycle of family harm. Everyone interviewed experienced severe adverse trauma reactions linked to mental health and addiction issues, self-harm and suicidality, and instances of family harm. A significant barrier to psychological and familial wellbeing was the lack of access to integrated models of care capable of responding to complex and intertwined issues in trauma informed and Indigenous informed ways. Thus, family harm, trauma and mental health and addiction services need to work together to tailor and deliver treatment according to the individual and family needs to break the cycle of family harm and ongoing adverse life course trajectories. 

This research identifies significant limitations in the psychological theories that usually contribute to thinking about family harm. There has been a particular failure to develop a theory that accounts for the heterogeneous cultural and gendered experiences of the cycle of family harm. Going forward, expanding the? view of traditional psychological theories of intergenerational trauma and violence is required to account for the historical trauma of colonisation and the ongoing adverse consequences for Indigenous communities. Family harm prevention initiatives must be led by and/or developed in partnership with and by Indigenous peoples to ensure responsivity through active incorporation of traditional practices for intergenerational healing and wellbeing.

The impact of poly-victimisation in childhood had severe and ongoing adverse consequences for both men and women that outweighed any obvious gender difference. For people who have experienced childhood maltreatment, it is essential to imbue initiatives with opportunities to understand emotions in relational contexts. Children who are placed in the care of the state must be cared for and, unlike the interviewees in this thesis, free from further childhood maltreatment. A therapeutic web should be established to stop the systemic issues identified in this thesis by providing cohesive and coherent services in a timely fashion for children and adults affected by the cycle of family harm. In conclusion, adopting practices that are informed by understandings of trauma, gender, and Indigenous knowledge are needed to replace the intergenerational transmission of trauma and violence with hope and wellbeing.

text: Making the invisible visible: Exploring the complex pathways between childhood experiences of maltreatment and the perpetration of family harm Preventing family harm and providing care for those affected is a high priority for governments and social services worldwide. Adverse consequences of family harm continue to place demands on justice, mental health and care and protection services. The costs to individuals, families and communities are beyond measure, given that rates of family harm are under-reported. Quantitative researchers have demonstrated a link between childhood maltreatment and family harm perpetration with existing psychological theories used to explain this link. However, mainstream theories were first developed many decades ago, at a time when the notion of gender was not inclusively factored into theory development. Neither were they developed with or by Indigenous peoples, calling into question the translatability of mainstream theories for stopping the intergenerational transmission of trauma and violence. 
The main aim of this thesis was to explore the relationship between childhood maltreatment and the perpetration of family harm by investigating two research questions. How could psychological theories better explain the pathways between childhood experiences of maltreatment and family harm perpetration? And, to what extent do psychological theories about the cycle of family harm reflect the experiences of Māori and non-Māori men and women in Aotearoa New Zealand? To answer these questions, interviews were conducted with 16 individuals who self-identified as perpetrating family harm and had childhood histories of maltreatment. (n=8 men, n=8 women). Purposive sampling ensured an equal number of Māori (Indigenous people of Aotearoa New Zealand) and non-Māori participated in the research. Thematic analysis was utilised to examine the personal conceptualisations regarding the association between experiences of childhood maltreatment and subsequent perpetration of family harm. The core corpus of data explored the maltreatment-family harm relationship within and between Māori and non-Māori men and women. This thesis is comprised of three studies that investigate the intergenerational transmission of trauma and violence.

The first study analysed the interviews of the seven participants removed from their families of origin as children. All described ongoing experiences of poly-victimisation in subsequent placements, whether through adoption, foster or residential settings. When examined alongside all women interviewed in this thesis, men more often reported that their childhood maltreatment was overlooked by professionals. The findings of this study highlighted a relationship between the perpetration of family harm and limited relational and emotional experiences during childhood. Intervention points across the life span were identified to stop the intergenerational transmission of trauma and violence for people removed from their family of origin as children.

The second study focused on the experiences of the eight Māori men and women interviewed. A culture of silence surrounding childhood maltreatment pervaded all interviewees’ childhood experiences. However, additional issues, including cultural isolation, were evident for Māori from the adults and professionals charged with their care. Māori interviewees identified three core Indigenous concepts that facilitated healing and intergenerational wellbeing: Wairua (spiritual connection), Pou (becoming a symbol of strength and support for self and others), and Tūrangawaewae (finding a sense of belonging). A return to Indigenous knowledge and practices was integral to stopping the intergenerational transmission of trauma and violence. This highlights the importance of privileging Indigenous knowledge in existing theoretical understanding of the cycle of family harm and incorporation in prevention initiatives.

The final study explored the impact of psychological distress within the cycle of family harm. Everyone interviewed experienced severe adverse trauma reactions linked to mental health and addiction issues, self-harm and suicidality, and instances of family harm. A significant barrier to psychological and familial wellbeing was the lack of access to integrated models of care capable of responding to complex and intertwined issues in trauma informed and Indigenous informed ways. Thus, family harm, trauma and mental health and addiction services need to work together to tailor and deliver treatment according to the individual and family needs to break the cycle of family harm and ongoing adverse life course trajectories. 

This research identifies significant limitations in the psychological theories that usually contribute to thinking about family harm. There has been a particular failure to develop a theory that accounts for the heterogeneous cultural and gendered experiences of the cycle of family harm. Going forward, expanding the? view of traditional psychological theories of intergenerational trauma and violence is required to account for the historical trauma of colonisation and the ongoing adverse consequences for Indigenous communities. Family harm prevention initiatives must be led by and/or developed in partnership with and by Indigenous peoples to ensure responsivity through active incorporation of traditional practices for intergenerational healing and wellbeing.

The impact of poly-victimisation in childhood had severe and ongoing adverse consequences for both men and women that outweighed any obvious gender difference. For people who have experienced childhood maltreatment, it is essential to imbue initiatives with opportunities to understand emotions in relational contexts. Children who are placed in the care of the state must be cared for and, unlike the interviewees in this thesis, free from further childhood maltreatment. A therapeutic web should be established to stop the systemic issues identified in this thesis by providing cohesive and coherent services in a timely fashion for children and adults affected by the cycle of family harm. In conclusion, adopting practices that are informed by understandings of trauma, gender, and Indigenous knowledge are needed to replace the intergenerational transmission of trauma and violence with hope and wellbeing.

year: 2022