title: A supercapacitor technique for efficiency improvement in linear regulators

authors: Kularatna, Nihal

subjects: engineering

abstract: Paper describes a novel supercapacitor based approach to recover the wasted energy in linear regulators. In this US patent pending technique, a single supercapacitor or an array of supercapacitors could be coupled with a linear series or shunt regulator, where the supercapacitors are charged by the input current of the regulator. This supercapacitor technique, by maintaining the dropout voltage limit before a new capacitor is placed in the series path, recovers the energy and does not use the supercapacitors for voltage conversion. Average efficiency of the overall circuit is improved by a significant amount, while maintaining the useful hall marks of a linear regulator. An example of a 12 to 5 volt proof of concept circuit is detailed with an overall efficiency improvement from 42% to over 78%. The technique is versatile, and, can be developed further to compete with the higher efficiency switching power supplies.

text: A supercapacitor technique for efficiency improvement in linear regulators Paper describes a novel supercapacitor based approach to recover the wasted energy in linear regulators. In this US patent pending technique, a single supercapacitor or an array of supercapacitors could be coupled with a linear series or shunt regulator, where the supercapacitors are charged by the input current of the regulator. This supercapacitor technique, by maintaining the dropout voltage limit before a new capacitor is placed in the series path, recovers the energy and does not use the supercapacitors for voltage conversion. Average efficiency of the overall circuit is improved by a significant amount, while maintaining the useful hall marks of a linear regulator. An example of a 12 to 5 volt proof of concept circuit is detailed with an overall efficiency improvement from 42% to over 78%. The technique is versatile, and, can be developed further to compete with the higher efficiency switching power supplies.

year: 2009

title: Microstructure and thermal stability of Al₂O₃-20vol%Fe₄₈Co₅₂ composite powder particles prepared by high energy mechanical milling

authors: Yusop, Masleeyati

subjects: High energy mechanical milling

abstract: High energy mechanical milling of a mixture of alumina and nanostructured Fe₄₈Co₅₂ powders was used in producing an Al₂O₃-20vol%Fe₄₈Co₅₂ composite powder. The milling time ranged from 8 to 48 hours. The microstructural changes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis of the powder showed significant reduction in Al₂O₃ grain size after 24h milling to 27nm and approaching the alloy grain size with further milling. However, the alloy particles demonstrated almost unchanged grain size throughout the process. As milling progressed, changes of alloy particles shapes and their location in alumina phases became apparent. After 24h, a small fraction of Al₂O₃  particles became embedded into the alloy particles, forming a complex composite structure. Small change in the microhardness of the particles was observed. It was also observed that the Fe₄₈Co₅₂ particles and Al₂O₃  matrix reacted heavily when the powder was heated to 10500°C.

text: Microstructure and thermal stability of Al₂O₃-20vol%Fe₄₈Co₅₂ composite powder particles prepared by high energy mechanical milling High energy mechanical milling of a mixture of alumina and nanostructured Fe₄₈Co₅₂ powders was used in producing an Al₂O₃-20vol%Fe₄₈Co₅₂ composite powder. The milling time ranged from 8 to 48 hours. The microstructural changes were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD analysis of the powder showed significant reduction in Al₂O₃ grain size after 24h milling to 27nm and approaching the alloy grain size with further milling. However, the alloy particles demonstrated almost unchanged grain size throughout the process. As milling progressed, changes of alloy particles shapes and their location in alumina phases became apparent. After 24h, a small fraction of Al₂O₃  particles became embedded into the alloy particles, forming a complex composite structure. Small change in the microhardness of the particles was observed. It was also observed that the Fe₄₈Co₅₂ particles and Al₂O₃  matrix reacted heavily when the powder was heated to 10500°C.

year: 2009

title: Ko wai tēnei e tū ake nei? Activating collectivity and accountability through grounded positioning

authors: Rata, Arama

abstract: Building on conference conversations about positionality—about who we are and how our identities shape our views of the world, about the connections and disconnections experienced between us, and about our proximities to place, power, and privilege—this piece brings together four conference participants to continue to reflect on what positionality means, on why it is important, and on how to practice it in non-performative, well-developed, and mutually nourishing ways. Their dialogue reflects active and critical positioning in process and practice, creating opportunities for acknowledging our relationships and activating both collectivity and accountability in the various spaces where we live, work, create, and hope.

text: Ko wai tēnei e tū ake nei? Activating collectivity and accountability through grounded positioning Building on conference conversations about positionality—about who we are and how our identities shape our views of the world, about the connections and disconnections experienced between us, and about our proximities to place, power, and privilege—this piece brings together four conference participants to continue to reflect on what positionality means, on why it is important, and on how to practice it in non-performative, well-developed, and mutually nourishing ways. Their dialogue reflects active and critical positioning in process and practice, creating opportunities for acknowledging our relationships and activating both collectivity and accountability in the various spaces where we live, work, create, and hope.

year: 2021-12