title: Interactive system modelling for the Internet of Things

authors: Bowen, Judy

subjects: interaction design

abstract: The rapid growth in the number of Internet of Things (IoT) systems and their increasing use in safety-critical domains has led to the need for an evolution of development methods. Model-Driven Development (MDD) approaches have been used in software engineering to reduce development time and minimize errors in implemented systems. This paper introduces a novel Model-Driven Development (MDD) approach for Internet of Things (IoT) systems which considers interactivity from the perspective of both users and IoT components. A real-world example is presented to explain the motivation for the work and demonstrate the benefits and use of lightweight interactive system models adapted for the design and development of IoT systems.

text: Interactive system modelling for the Internet of Things The rapid growth in the number of Internet of Things (IoT) systems and their increasing use in safety-critical domains has led to the need for an evolution of development methods. Model-Driven Development (MDD) approaches have been used in software engineering to reduce development time and minimize errors in implemented systems. This paper introduces a novel Model-Driven Development (MDD) approach for Internet of Things (IoT) systems which considers interactivity from the perspective of both users and IoT components. A real-world example is presented to explain the motivation for the work and demonstrate the benefits and use of lightweight interactive system models adapted for the design and development of IoT systems.

year: 2023

title: Supercapacitor-based linear converter for voltage regulator modules

authors: Wickramasinghe, Thilini Chintha Prabha Kumari

subjects: DC-DC converter

abstract: This thesis investigates a linear converter technique suitable for microprocessor voltage regulator modules (VRMs). The original linear regulator is the patented supercapacitor assisted low-dropout regulator (SCALDO). A less complex, lower cost design was achieved by reducing the number of switches in the original SCALDO and adding a second low dropout regulator (LDO).
In the initial implementation of this reduced-switch SCALDO (RS-SCALDO), output regulation failed due to the presence of a parasitic body-diode in standard LDOs. The body-diode forms an unwanted discharge path to ground for the supercapacitor. In order to block this path, an application specific LDO that operates in the third quadrant of a MOSFET current-vs-voltage transfer function was investigated.
A 3.5-to-1.5 V RS-SCALDO was designed with a supercapacitor, two LDOs and two switches. Compared with the standard SCALDO approach, this new design halves the number of switches required. Discrete MOSFET-based high-current LDOs were developed and combined with a common feedback control circuit. Voltage identification (VID) capability was implemented using a digital potentiometer. Theoretically, when an LDO converts 3.5 V to 1.5 V a maximum efficiency of 1.5/3.5(~43%) can be achieved. According to the general theory of SCALDO, a single supercapacitor configuration can achieve nearly twice the linear regulator efficiency. The 3.5-to-1.5 V, 5 A RS-SCALDO achieved an approximate end-to-end efficiency of 80%, thus, agreeing with SCALDO general theory.
Large-signal analysis was used to model MOSFET non-linearities and predict the performance of LDOs, switches and the overall system. Matlab  modeling predictions for body-diode behaviour were cross-checked via SPICE simulation; the results agreed with bench measurements.
RS-SCALDO regulators cycle at very low frequencies, usually in the range of millihertz to hertz. Therefore, electromagnetic interference emitted by high-frequency switched-mode VRMs is not an issue here. Compared to typical high-frequency VRMs, RS-SCALDO topology provides similar efficiencies with the high slew-rate and low noise output of a linear regulator. In generalized SCALDO configuration with n supercapacitors, a total of 3n+1 switches required; in contrast RS-SCALDO reduces the switch count to 2n. With the elimination of the body-diode parasitics, the technique can be extended to much higher currents.

text: Supercapacitor-based linear converter for voltage regulator modules This thesis investigates a linear converter technique suitable for microprocessor voltage regulator modules (VRMs). The original linear regulator is the patented supercapacitor assisted low-dropout regulator (SCALDO). A less complex, lower cost design was achieved by reducing the number of switches in the original SCALDO and adding a second low dropout regulator (LDO).
In the initial implementation of this reduced-switch SCALDO (RS-SCALDO), output regulation failed due to the presence of a parasitic body-diode in standard LDOs. The body-diode forms an unwanted discharge path to ground for the supercapacitor. In order to block this path, an application specific LDO that operates in the third quadrant of a MOSFET current-vs-voltage transfer function was investigated.
A 3.5-to-1.5 V RS-SCALDO was designed with a supercapacitor, two LDOs and two switches. Compared with the standard SCALDO approach, this new design halves the number of switches required. Discrete MOSFET-based high-current LDOs were developed and combined with a common feedback control circuit. Voltage identification (VID) capability was implemented using a digital potentiometer. Theoretically, when an LDO converts 3.5 V to 1.5 V a maximum efficiency of 1.5/3.5(~43%) can be achieved. According to the general theory of SCALDO, a single supercapacitor configuration can achieve nearly twice the linear regulator efficiency. The 3.5-to-1.5 V, 5 A RS-SCALDO achieved an approximate end-to-end efficiency of 80%, thus, agreeing with SCALDO general theory.
Large-signal analysis was used to model MOSFET non-linearities and predict the performance of LDOs, switches and the overall system. Matlab  modeling predictions for body-diode behaviour were cross-checked via SPICE simulation; the results agreed with bench measurements.
RS-SCALDO regulators cycle at very low frequencies, usually in the range of millihertz to hertz. Therefore, electromagnetic interference emitted by high-frequency switched-mode VRMs is not an issue here. Compared to typical high-frequency VRMs, RS-SCALDO topology provides similar efficiencies with the high slew-rate and low noise output of a linear regulator. In generalized SCALDO configuration with n supercapacitors, a total of 3n+1 switches required; in contrast RS-SCALDO reduces the switch count to 2n. With the elimination of the body-diode parasitics, the technique can be extended to much higher currents.

year: 2016

title: Anhedonia: He kohinga whiti mai i te tirohanga o ngā wahanga e rima o te pōuri / A collection of poetry themed around loss presented through the lens of the five stages of grief

authors: Nicholls, Rawiri Rangihouhiri Terrence

subjects: Grief

abstract: Anhedonia is a collection of personal experiences centred around loss examined through the lens of the five stages of grief (denial, anger, bargaining, depression, and acceptance) and framed within a personal confessional postmodernism style. It was also influenced by the collected works of Federico Garcia Lorca, Sylvia Plath, Cassandra Barnett (Ngāti Huri, Raukawa), Kirsty Dunn (Te Aupōuri, Te Rarawa), and Ngahuia Te Awekotuku (Te Arawa, Tūhoe).

While loss and grief are intrinsically linked to death, within this collection, I further explore other forms of loss and grief. I touch on my loss of cultural identity, mind, and self. As a student, I have been diving deeper into my cultural identity of being Māori and what that means to me. I have lost many things throughout my life at the hands of abuse, depression, grief, and mental health. The poetry within this collection will continue to serve as a blunt reminder of the experiences (both positive and negative) that I have endured or witnessed over the last couple of decades.

I have seen a multitude of losses (in its many variations) as I continue the dance to discover what the mortality of not only myself but those around me means to me. While everyone will experience feelings of grief and loss, I have framed my own experiences in my interpretation of our collective mortality.

text: Anhedonia: He kohinga whiti mai i te tirohanga o ngā wahanga e rima o te pōuri / A collection of poetry themed around loss presented through the lens of the five stages of grief Anhedonia is a collection of personal experiences centred around loss examined through the lens of the five stages of grief (denial, anger, bargaining, depression, and acceptance) and framed within a personal confessional postmodernism style. It was also influenced by the collected works of Federico Garcia Lorca, Sylvia Plath, Cassandra Barnett (Ngāti Huri, Raukawa), Kirsty Dunn (Te Aupōuri, Te Rarawa), and Ngahuia Te Awekotuku (Te Arawa, Tūhoe).

While loss and grief are intrinsically linked to death, within this collection, I further explore other forms of loss and grief. I touch on my loss of cultural identity, mind, and self. As a student, I have been diving deeper into my cultural identity of being Māori and what that means to me. I have lost many things throughout my life at the hands of abuse, depression, grief, and mental health. The poetry within this collection will continue to serve as a blunt reminder of the experiences (both positive and negative) that I have endured or witnessed over the last couple of decades.

I have seen a multitude of losses (in its many variations) as I continue the dance to discover what the mortality of not only myself but those around me means to me. While everyone will experience feelings of grief and loss, I have framed my own experiences in my interpretation of our collective mortality.

year: 2024