title: Energy-Efficient SMPS-Based Pulse Generator for Neurostimulators

authors: Seshadri, Sinduja

subjects: pulse generator

abstract: There is a need in the neuromodulation industry for a very energy-efficient pulse generator. Little data is observed in literature to develop a power efficient pulse generator that can deliver the required stimulus. A typical stimulator has a boost stage, a low-dropout (LDO) stage and an analog circuit that delivers the stimulus in the form of a pulse to the patient. Such a system is found to be ∼ 40% efficient. There are two new methods that can improve this efficiency rating significantly. (1) A mod- ification to existing pulse generator by adding microprocessors to control the output voltages of boost and LDO in the circuit, as proposed by the manufacturer; (2) a Single-Ended Primary Inductance Converter (SEPIC) based design proposed by the authors, with the input connected to a battery and the output to electrodes. Comparing with existing design, the modification offered a consistent 75% efficiency for output voltages from 3.9V to 6.6V. SEPIC had an efficiency rating of 80% to 86% across the same voltage range.

text: Energy-Efficient SMPS-Based Pulse Generator for Neurostimulators There is a need in the neuromodulation industry for a very energy-efficient pulse generator. Little data is observed in literature to develop a power efficient pulse generator that can deliver the required stimulus. A typical stimulator has a boost stage, a low-dropout (LDO) stage and an analog circuit that delivers the stimulus in the form of a pulse to the patient. Such a system is found to be ∼ 40% efficient. There are two new methods that can improve this efficiency rating significantly. (1) A mod- ification to existing pulse generator by adding microprocessors to control the output voltages of boost and LDO in the circuit, as proposed by the manufacturer; (2) a Single-Ended Primary Inductance Converter (SEPIC) based design proposed by the authors, with the input connected to a battery and the output to electrodes. Comparing with existing design, the modification offered a consistent 75% efficiency for output voltages from 3.9V to 6.6V. SEPIC had an efficiency rating of 80% to 86% across the same voltage range.

year: 2019

title: Analysis of skim milk powder deposition on stainless steel tubes in cross-flow

authors: Walmsley, Timothy Gordon

subjects: heat exchanger

abstract: Particulate fouling on the gas side of heat recovery equipment is a common industrial problem. The aim of this study is to characterize the deposition of skim milk powder on a single bare tube in cross-flow. A custom built rig is applied to simulate exhaust air conditions that is experienced in an exhaust exchanger. For a constant airflow rate, increasing particle stickiness resulted in greater deposition coverage around the front of the round and elliptical tubes peaking in the middle, whereas the turned square tube tended to be either clear or covered. Results show that the skim milk powder particle impact angle on the tube, as opposed to the wall shear stress, is an important determinant for deposition. During each test and at the conclusion of each test, which was when fouling reached an asymptote, the amount of deposition coverage and build-up on the tube varied depending on the tube shape, particle stickiness, and air velocity.

text: Analysis of skim milk powder deposition on stainless steel tubes in cross-flow Particulate fouling on the gas side of heat recovery equipment is a common industrial problem. The aim of this study is to characterize the deposition of skim milk powder on a single bare tube in cross-flow. A custom built rig is applied to simulate exhaust air conditions that is experienced in an exhaust exchanger. For a constant airflow rate, increasing particle stickiness resulted in greater deposition coverage around the front of the round and elliptical tubes peaking in the middle, whereas the turned square tube tended to be either clear or covered. Results show that the skim milk powder particle impact angle on the tube, as opposed to the wall shear stress, is an important determinant for deposition. During each test and at the conclusion of each test, which was when fouling reached an asymptote, the amount of deposition coverage and build-up on the tube varied depending on the tube shape, particle stickiness, and air velocity.

year: 2015

title: Alice Grey Nicholls, daughter of William, and her husband, Charles John Dearle

authors: Hart, Philip

abstract: Alice Grey Nicholls was the ‘half-caste’ daughter of a Pakeha Maori, William Nicholls. She would marry a Pakeha and have several children, losing her only son but bringing up a family of daughters, who all received a Pakeha education. Having a moko emphasized her Maori heritage, and she was on good terms with many Maori.
Charles John Dearle, a Londoner, after some involvement in gold mining spent most of his life working for the government. At the request of Maori landowners, from 1883 until 1895 he allocated goldfields revenue amongst them, a challenging task. He was also involved in land purchases both on behalf of the government and for personal gain. 
They farmed her land at Mangaiti, near Te Aroha, Alice continuing to farm it profitably after his early death, assisted for a time by her daughters. She purchased more land, and to enable her to sell some portions of it she had it declared European land, an illustration of her astuteness in business; her family obtained a good financial position from her farming and land dealings. When she died, aged 81, her Pakeha friends fondly remembered her.

text: Alice Grey Nicholls, daughter of William, and her husband, Charles John Dearle Alice Grey Nicholls was the ‘half-caste’ daughter of a Pakeha Maori, William Nicholls. She would marry a Pakeha and have several children, losing her only son but bringing up a family of daughters, who all received a Pakeha education. Having a moko emphasized her Maori heritage, and she was on good terms with many Maori.
Charles John Dearle, a Londoner, after some involvement in gold mining spent most of his life working for the government. At the request of Maori landowners, from 1883 until 1895 he allocated goldfields revenue amongst them, a challenging task. He was also involved in land purchases both on behalf of the government and for personal gain. 
They farmed her land at Mangaiti, near Te Aroha, Alice continuing to farm it profitably after his early death, assisted for a time by her daughters. She purchased more land, and to enable her to sell some portions of it she had it declared European land, an illustration of her astuteness in business; her family obtained a good financial position from her farming and land dealings. When she died, aged 81, her Pakeha friends fondly remembered her.

year: 2016