title: Potential of supercapacitors in novel power converters as semi-ideal lossless voltage droppers

authors: Ariyarathna, Thilanga

subjects: Science & Technology

abstract: Electrical physics text book theory tells us that charging a capacitor is much less efficient than replenishing the energy in a discharged electro-chemical battery. If a fully discharged capacitor is pumped with a charge of Q coulombs, it stores 1/2QV while dissipating the same amount of energy in the loop resistance. However, if the same charge is pumped into a re-chargeable electrochemical cell of voltage V the energy stored in the cell is QV, while the wasted energy is determined by the loop resistance and the voltage difference across the resistance. If a rechargeable battery pack is to be replaced by a supercapacitor module, this difference could seriously affect the design of power converters required, since the power converter should stop charging at a certain point to avoid overcharging the capacitor bank. However, if a useful resistive load such as heater, DC-DC converter, inverter or a lamp load is used as a part of the loop resistance in a capacitor charging loop, a significant part of this loss can be recovered. One example of this is in the supercapacitor assisted low drop-out regulator (SCALDO) technique. This paper will detail the concept of circumvention of RC loop charging loss, theoretically quantifying the same in a generalized circuit, demonstrating how this can be applied in completely novel circuit topologies such as the supercapacitor assisted LED (SCALED) converter. The paper will provide experimental results of selected SCALDO implementations and early results of SCALED technique to support this theory.

text: Potential of supercapacitors in novel power converters as semi-ideal lossless voltage droppers Electrical physics text book theory tells us that charging a capacitor is much less efficient than replenishing the energy in a discharged electro-chemical battery. If a fully discharged capacitor is pumped with a charge of Q coulombs, it stores 1/2QV while dissipating the same amount of energy in the loop resistance. However, if the same charge is pumped into a re-chargeable electrochemical cell of voltage V the energy stored in the cell is QV, while the wasted energy is determined by the loop resistance and the voltage difference across the resistance. If a rechargeable battery pack is to be replaced by a supercapacitor module, this difference could seriously affect the design of power converters required, since the power converter should stop charging at a certain point to avoid overcharging the capacitor bank. However, if a useful resistive load such as heater, DC-DC converter, inverter or a lamp load is used as a part of the loop resistance in a capacitor charging loop, a significant part of this loss can be recovered. One example of this is in the supercapacitor assisted low drop-out regulator (SCALDO) technique. This paper will detail the concept of circumvention of RC loop charging loss, theoretically quantifying the same in a generalized circuit, demonstrating how this can be applied in completely novel circuit topologies such as the supercapacitor assisted LED (SCALED) converter. The paper will provide experimental results of selected SCALDO implementations and early results of SCALED technique to support this theory.

year: 2017

title: Spike oscillations

authors: Heinzle, J. Mark

subjects: dynamical-systems approach

abstract: According to Belinskii., Khalatnikov and Lifshitz (BKL), a generic spacelike singularity is characterized by asymptotic locality: Asymptotically, toward the singularity, each spatial point evolves independently from its neighbors, in an oscillatory manner that is represented by a sequence of Bianchi type I and II vacuum models. Recent investigations support this conjecture but with a modification: Apart from local BKL behavior there also exists formation of spatial structures ("spikes") at, and in the neighborhood of, certain spatial surfaces that break asymptotic locality; the complete description of a generic spacelike singularity involves spike oscillations, which are described by sequences of Bianchi type I and certain inhomogeneous vacuum models. In this paper we describe how BKL and spike oscillations arise from concatenations of exact solutions in a Hubble-normalized state space setting, suggesting the existence of hidden symmetries and showing that the results of BKL are part of a greater picture.

text: Spike oscillations According to Belinskii., Khalatnikov and Lifshitz (BKL), a generic spacelike singularity is characterized by asymptotic locality: Asymptotically, toward the singularity, each spatial point evolves independently from its neighbors, in an oscillatory manner that is represented by a sequence of Bianchi type I and II vacuum models. Recent investigations support this conjecture but with a modification: Apart from local BKL behavior there also exists formation of spatial structures ("spikes") at, and in the neighborhood of, certain spatial surfaces that break asymptotic locality; the complete description of a generic spacelike singularity involves spike oscillations, which are described by sequences of Bianchi type I and certain inhomogeneous vacuum models. In this paper we describe how BKL and spike oscillations arise from concatenations of exact solutions in a Hubble-normalized state space setting, suggesting the existence of hidden symmetries and showing that the results of BKL are part of a greater picture.

year: 2012

title: Family structure and change in early childhood and the wellbeing of tamariki Maori

authors: Kukutai, Tahu

subjects: family structure

abstract: Internationally there is growing evidence that family structure, and changes in structure, have an impact on children’s health and wellbeing and the intergenerational transmission of inequity. The effects, however, vary by socio-economic context and ethnicity. Using longitudinal data from Growing Up in New Zealand (n = 1349), we examine family structure and change for tamariki Māori during early childhood, and the potential impacts on their development and wellbeing. We find that a stable two-parent family is the primary experience for tamariki Māori, and sole parenthood is transitory. Diverse family trajectories appear to be linked to poorer cognitive and socio-emotional outcomes but are not the main driver. More important are maternal factors, notably age and education, and material hardship. Importantly, higher levels of cultural connectedness among tamariki Māori, which are associated with diverse family forms, seem to promote socio-emotional development. Our study provides further incentive for policy and programmes that centre equity and support access to the determinants of health for tamariki Māori.

text: Family structure and change in early childhood and the wellbeing of tamariki Maori Internationally there is growing evidence that family structure, and changes in structure, have an impact on children’s health and wellbeing and the intergenerational transmission of inequity. The effects, however, vary by socio-economic context and ethnicity. Using longitudinal data from Growing Up in New Zealand (n = 1349), we examine family structure and change for tamariki Māori during early childhood, and the potential impacts on their development and wellbeing. We find that a stable two-parent family is the primary experience for tamariki Māori, and sole parenthood is transitory. Diverse family trajectories appear to be linked to poorer cognitive and socio-emotional outcomes but are not the main driver. More important are maternal factors, notably age and education, and material hardship. Importantly, higher levels of cultural connectedness among tamariki Māori, which are associated with diverse family forms, seem to promote socio-emotional development. Our study provides further incentive for policy and programmes that centre equity and support access to the determinants of health for tamariki Māori.

year: 2020