Abstract Surge protection is intended to provide protection against overvoltages in power systems... more Abstract Surge protection is intended to provide protection against overvoltages in power systems. In order for a system to have adequate surge protection, transient phenomena studies must be carried out and a surge protection scheme must be designed using the data obtained from the studies. The degree of accuracy of these studies will vary with the quality of modeling and simulation. System models to be used in the studies should include station busbars since stations constitute substantial parts of the systems. This paper discusses a transient phenomena study which was performed on an operative 138 kV multi-line underground power distribution system to investigate how the most effective surge protection scheme for the system may be implemented using ZnO surge arresters. Emphasis is stressed on modeling the busbar at the substation of the system.
Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applica... more Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applications on September 2023. : Power hardware-in-the-loop (PHIL) is a modern experimental technique that allows emulation of a full-scale converter (FSC) with the combination of a scaled-down converter (SDC), power amplifier, and real-time simulator, thus enabling the study of real-time interactions of power electronics with large power systems. However, assembling an accurate scaled-down replica of an FSC with off-the-shelf laboratory SDCs is practically impossible due to a mismatch in per unit losses, as well as in the impedance of the L/LC/LCL filter. Consequently, the scaled-up power flow capability of SDCs differs from FSCs, restricting emulation to smaller regions of the four quadrants than those corresponding to the FSCs nominal active and reactive capacity. These PHIL test beds cannot be used to emulate FSCs demanding bidirectional active and reactive power flow. Any scaling method o...
2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC)
Extraction of in-circuit impedance of an electrical system under its normal operating condition w... more Extraction of in-circuit impedance of an electrical system under its normal operating condition without direct electrical contact has been well-established based on inductively coupling method. This method is useful for noise source impedance extraction of power converter and condition monitoring of critical electrical infrastructures. For in-circuit impedance extraction of high power noisy electrical system, good signal-to-noise ratio and test instrument protection are necessary. This paper proposes a new measurement approach to fulfill such requirements.
Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applica... more Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applications on January 2023. : Power hardware-in-the-loop (PHIL) is an experimental technique that uses power amplifiers and real-time simulators for studying the dynamics of power electronic converters and electrical grids. PHIL tests provide the means for functional validation of advanced control algorithms without the burden of building high-power prototypes during early technology readiness levels. However, replicating the behavior of high-power systems with laboratory scaled-down converters (SDCs) can be complex. Inaccurate scaling of the SDCs coupled with an exclusive focus on instantaneous voltages and currents at the fundamental frequency can lead to PHIL results that are only partially relatable to the high-power systems under study. Test beds that fail to represent switching frequency harmonics cannot be used for studying harmonic penetration or loss characterization of large-scale c...
Aim: The objective of this study was to determine the effect of sweet potato virus disease (SPVD)... more Aim: The objective of this study was to determine the effect of sweet potato virus disease (SPVD) on the beta carotene content, tuber weight and vine weight of selected popular sweet potato genotypes. Study Design: The experiment was laid as a randomized complete block design (RCBD) with three replications. Place and Duration of Study: The experiment was conducted for two cropping seasons (2015/16 and 2016/17) at the Zambia Agriculture Research Institute in Chilanga district of Zambia. Methodology: The uninfected (control) genotypes of Kanga, Chiwoko and Chingovwa were evaluated alongside their SPVD infected genotypes. Genotypic infection was confirmed using molecular approaches, and data was collected at harvest on beta carotene content, tuber weight and vine weight. Results: The results showed that SPVD affects the yield and beta carotene content of sweet potato. Significant differences (P< .001) for yield performance and beta carotene were observed. The yield reduction in perc...
2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL)
Due to high-frequency common-mode (CM) voltage and induced CM current, bearings of inverter-drive... more Due to high-frequency common-mode (CM) voltage and induced CM current, bearings of inverter-driven induction machines suffer from electrical discharge machining(EDM) which may cause premature bearing failures such as damage of the bearing surfaces and degradation of lubrication grease. Meanwhile, the bearing EDM process is always accompanied by conducted and radiated electromagnetic interference (EMI) emissions. In this paper, simulation of a 5.5 kW induction machine driven by a PWM-controlled voltage source inverter (VSI) is introduced and an improved discharge circuit across the motor bearing is designed to simulate the EDM process. High frequency modelling of the cable and induction machine matches well with measurement results. EDM process happens when a controlled switch across the machine bearing closes, which means a sudden drop of bearing voltage. During the discharge instant, a harmful EDM current flows through the compromised bearing and reduces bearing life.
GamePlan4Care (GP4C) is a web-based adaptation of the Resources for Enhancing Alzheimer’s Caregiv... more GamePlan4Care (GP4C) is a web-based adaptation of the Resources for Enhancing Alzheimer’s Caregiver Health II (REACH II) caregiver intervention, redesigned and reformatted for online delivery. The goal of GP4C is to create an online family caregiver support platform that facilitates self-directed exposure to evidence-based skills-training and support for dementia caregivers. This approach of utilizing technology enhanced with live support has the potential for scalability and sustainability. In preparation for an ongoing randomized clinical trial, the GP4C platform underwent industry standard user interface/user experience (UI/UX) testing with dementia caregivers as part of an iterative design process. Testing of caregiver’s reaction to technical and content-related aspects of the system was conducted with 31 caregivers. The thematic analysis revealed three themes for technical aspects (logical flow, suggestions on features, innovative resource) and two themes for content aspects (s...
Badain Jaran Desert (BJD), characterized by extremely arid climate and tallest sand dunes in the ... more Badain Jaran Desert (BJD), characterized by extremely arid climate and tallest sand dunes in the world, is the second largest desert in China. Surprisingly, there are a large number of permanent lakes in this desert. At present, little is known about the composition and distribution of microbial communities in these desert lakes, which are an important bioresource and play a fundamental role in the elemental cycles of the lakes. In this study, the physicochemical characteristics and microbial communities of water samples from 15 lakes in BJD were comparatively investigated. The results showed that the lakes were rich in Na+, Cl-, CO32- and HCO3- while Ca2+ and Mg2+ were scarce, with pH 8.52-10.27 and salinity 1.05-478.70 g/L. Bacteria dominated exclusively in low saline lakes (salinity < 50 g/L) while archaea were predominant in hypersaline lakes (salinity > 250 g/L), which abundance increased along salinity gradient linearly. Genera Flavobacterium, Synechocystis and Roseobacter from phyla Bacteroidetes, Cyanobacteria, Alphaproteobacteria were the major members in low saline lakes whereas Halomonas, Aliidiomarina and Halopelagius from Gammaproteobacteria and Euryarchaeota were abundant in moderately saline lakes (salinity 50-250 g/L). The hypersaline lakes were predominated by extreme halophiles such as Halorubrum, Halohasta and Natronomonas from Euryarchaeota. The correlation among the microbes in the lakes was mainly positive, suggesting they can survive in the harsh environments through synergistic interactions. Statistical analyses indicated that physicochemical characteristics rather than spatial factors shaped the microbial communities in the desert lakes. The pH was the most important environmental factor controlling alpha diversity, while salinity was the major driver determining microbial community structure in BJD lakes. In contrast, geographic factors had no significant impact on the microbial community compositions.
The reclamation of mine dump is largely centered on the role played by microorganisms. However, t... more The reclamation of mine dump is largely centered on the role played by microorganisms. However, the succession of microbial community structure and function in ecological restoration of the mine soils is still poorly understood. In this study, soil samples with different stacking time were collected from the dump of an iron mine in China and the physicochemical characteristics and microbial communities of these samples were comparatively investigated. The results showed that the fresh bare samples had the lowest pH, highest ion concentration, and were the most deficient in nutrients while the acidity and ion concentration of old bare samples decreased significantly, and the nutritional conditions improved remarkably. Vegetated samples had the weakest acidity, lowest ion concentration, and the highest nutrient concentration. In the fresh mine soils, the iron/sulfur-oxidizers such as Acidiferrobacter and Sulfobacillus were dominant, resulting in the strongest acidity. Bacteria from ge...
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
Modern day advancements in electrical engineering especially power generation and management has ... more Modern day advancements in electrical engineering especially power generation and management has enabled the path for More Electrical Aircrafts (MEAs) and hybrid propulsion systems. The electrical power generation in aerospace system is in itself an isolated micro grid with ac and dc components operating in either series or parallel or in hybrid mode. Uninterrupted and stable operation of these systems is of utmost importance. Known stability methods based on Lyapunov are difficult to implement as generalized on-line stability assessment procedure for such complex power network. In this paper a detailed and systematic small signal stability analysis of a More Electric Aircraft electrical power generation system is presented based on the eigen value analysis. The effect of different control algorithms on the MEE/MEA power network stability is studied using the proposed method. Also, it is shown that the stability is improved by using optimal gain feed-forward information of dc-bus currents. The stability matrix for the whole operating regime is developed and the stability margin variation for different operating conditions and control variations is presented. The efficacy of the estimated stability margin for MEE/MEA power network is verified using an Opal-RT Virtual test bed for all the control configurations.
Abstract Acidophiles play a vital catalytic role in the formation of acid mine drainage (AMD). In... more Abstract Acidophiles play a vital catalytic role in the formation of acid mine drainage (AMD). In this study, acidophilic communities in a stream, two lakes and five ponds in Nanshan Mine, Anhui Province, China were comparatively investigated. Among the three types of AMDs, the stream which originated from a rock wall had the strongest acidity (pH 2.30–2.42), while the ponds (pH 2.35–2.60) formed in mine dump and the two large-scale AMD lakes (pH 2.66–3.05) were less acidic. The chemolithotrophic iron-oxidizer Leptospirillum dominated at the stream starting point with the lowest pH and highest Fe content. However, with streamflow, pH increased and Fe concentration decreased dramatically, and the dominance of Leptospirillum was replaced by the less acid-resistant iron-oxidizer Ferrovum. In contrast to the stream, prokaryotic communities in the ponds were mostly dominated by chemoheterotrophic Acidiphilium because of the abundant organic matter from surrounding mine waste. Both chemolithotrophic Ferrovum and chemoheterotrophic Acidiphilium were abundant in the AMD lakes, which may form a symbiotic relationship around the carbon cycle. Statistical analyses indicated that pH was the predominant environmental factor influencing the prokaryotic communities. As for the eukaryotic communities, the microeukaryotes in the stream were mostly uncultured groups. Both photoautotrophic algae Chrysonebula and chemoheterotrophic fungi were abundant in the ponds, while the two AMD lakes were only dominated by photoautotrophic algae Coccomyxa and Ochromonas.
ABSTRACT The analytical proof showing that output voltage droop characteristics of parallel-conne... more ABSTRACT The analytical proof showing that output voltage droop characteristics of parallel-connected DC-DC power converters are only appropriate for limited applications is presented. Because power converters are very seldom identical, near-uniform current-sharing without additional control can be achieved only when paralleled power converters have similar characteristics and behave like ideal current sources. This can be achieved at the expense of poor voltage regulation. As an alternative, a current-sharing control technique, which requires no remote sensing, is proposed. This technique ensures uniform or designated current distribution throughout specified load range. A control circuit module is independently implemented without any preliminary knowledge or any circuit modification of the source power converters
The Zambia Defence Force adopted the Standards-Based Management and Recognition approach to impro... more The Zambia Defence Force adopted the Standards-Based Management and Recognition approach to improve the quality of the HIV-related services at its health facilities. This quality improvement intervention relies on comprehensive, detailed assessment tools to communicate and verify adherence to national standards of care, and to test and implement changes to improve performance. A quasi-experimental evaluation of the intervention was conducted at eight Zambia Defence Force primary health facilities (four facilities implemented the intervention and four did not). Data from three previous analyses are combined to assess the effect of Standards-Based Management and Recognition on three domains: facility readiness to provide services; observed provider performance during antiretroviral therapy (ART) and antenatal care consultations; and provider perceptions of the work environment. Facility readiness scores for ART improved on four of the eight standards at intervention sites, and one standard at comparison sites. Facility readiness scores for prevention of mother-to-child transmission (PMTCT) of HIV increased by 15 percentage points at intervention sites and 7 percentage points at comparison sites. Provider performance improved significantly at intervention sites for both ART services (from 58 to 84%; P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) and PMTCT services (from 58 to 73%; P = 0.003); there was no significant change at comparison sites. Providers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; perceptions of the work environment generally improved at intervention sites and declined at comparison sites; differences in trends between study groups were significant for eight items. A standards-based approach to quality improvement proved effective in supporting healthcare managers and providers to deliver ART and PMTCT services in accordance with evidence-based standards in a health system suffering from staff shortages.
Abstract Surge protection is intended to provide protection against overvoltages in power systems... more Abstract Surge protection is intended to provide protection against overvoltages in power systems. In order for a system to have adequate surge protection, transient phenomena studies must be carried out and a surge protection scheme must be designed using the data obtained from the studies. The degree of accuracy of these studies will vary with the quality of modeling and simulation. System models to be used in the studies should include station busbars since stations constitute substantial parts of the systems. This paper discusses a transient phenomena study which was performed on an operative 138 kV multi-line underground power distribution system to investigate how the most effective surge protection scheme for the system may be implemented using ZnO surge arresters. Emphasis is stressed on modeling the busbar at the substation of the system.
Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applica... more Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applications on September 2023. : Power hardware-in-the-loop (PHIL) is a modern experimental technique that allows emulation of a full-scale converter (FSC) with the combination of a scaled-down converter (SDC), power amplifier, and real-time simulator, thus enabling the study of real-time interactions of power electronics with large power systems. However, assembling an accurate scaled-down replica of an FSC with off-the-shelf laboratory SDCs is practically impossible due to a mismatch in per unit losses, as well as in the impedance of the L/LC/LCL filter. Consequently, the scaled-up power flow capability of SDCs differs from FSCs, restricting emulation to smaller regions of the four quadrants than those corresponding to the FSCs nominal active and reactive capacity. These PHIL test beds cannot be used to emulate FSCs demanding bidirectional active and reactive power flow. Any scaling method o...
2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility (EMC/APEMC)
Extraction of in-circuit impedance of an electrical system under its normal operating condition w... more Extraction of in-circuit impedance of an electrical system under its normal operating condition without direct electrical contact has been well-established based on inductively coupling method. This method is useful for noise source impedance extraction of power converter and condition monitoring of critical electrical infrastructures. For in-circuit impedance extraction of high power noisy electrical system, good signal-to-noise ratio and test instrument protection are necessary. This paper proposes a new measurement approach to fulfill such requirements.
Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applica... more Manuscript submitted to the IEEE Industry Applications Society’s Open Journal of Industry Applications on January 2023. : Power hardware-in-the-loop (PHIL) is an experimental technique that uses power amplifiers and real-time simulators for studying the dynamics of power electronic converters and electrical grids. PHIL tests provide the means for functional validation of advanced control algorithms without the burden of building high-power prototypes during early technology readiness levels. However, replicating the behavior of high-power systems with laboratory scaled-down converters (SDCs) can be complex. Inaccurate scaling of the SDCs coupled with an exclusive focus on instantaneous voltages and currents at the fundamental frequency can lead to PHIL results that are only partially relatable to the high-power systems under study. Test beds that fail to represent switching frequency harmonics cannot be used for studying harmonic penetration or loss characterization of large-scale c...
Aim: The objective of this study was to determine the effect of sweet potato virus disease (SPVD)... more Aim: The objective of this study was to determine the effect of sweet potato virus disease (SPVD) on the beta carotene content, tuber weight and vine weight of selected popular sweet potato genotypes. Study Design: The experiment was laid as a randomized complete block design (RCBD) with three replications. Place and Duration of Study: The experiment was conducted for two cropping seasons (2015/16 and 2016/17) at the Zambia Agriculture Research Institute in Chilanga district of Zambia. Methodology: The uninfected (control) genotypes of Kanga, Chiwoko and Chingovwa were evaluated alongside their SPVD infected genotypes. Genotypic infection was confirmed using molecular approaches, and data was collected at harvest on beta carotene content, tuber weight and vine weight. Results: The results showed that SPVD affects the yield and beta carotene content of sweet potato. Significant differences (P< .001) for yield performance and beta carotene were observed. The yield reduction in perc...
2017 Progress in Electromagnetics Research Symposium - Fall (PIERS - FALL)
Due to high-frequency common-mode (CM) voltage and induced CM current, bearings of inverter-drive... more Due to high-frequency common-mode (CM) voltage and induced CM current, bearings of inverter-driven induction machines suffer from electrical discharge machining(EDM) which may cause premature bearing failures such as damage of the bearing surfaces and degradation of lubrication grease. Meanwhile, the bearing EDM process is always accompanied by conducted and radiated electromagnetic interference (EMI) emissions. In this paper, simulation of a 5.5 kW induction machine driven by a PWM-controlled voltage source inverter (VSI) is introduced and an improved discharge circuit across the motor bearing is designed to simulate the EDM process. High frequency modelling of the cable and induction machine matches well with measurement results. EDM process happens when a controlled switch across the machine bearing closes, which means a sudden drop of bearing voltage. During the discharge instant, a harmful EDM current flows through the compromised bearing and reduces bearing life.
GamePlan4Care (GP4C) is a web-based adaptation of the Resources for Enhancing Alzheimer’s Caregiv... more GamePlan4Care (GP4C) is a web-based adaptation of the Resources for Enhancing Alzheimer’s Caregiver Health II (REACH II) caregiver intervention, redesigned and reformatted for online delivery. The goal of GP4C is to create an online family caregiver support platform that facilitates self-directed exposure to evidence-based skills-training and support for dementia caregivers. This approach of utilizing technology enhanced with live support has the potential for scalability and sustainability. In preparation for an ongoing randomized clinical trial, the GP4C platform underwent industry standard user interface/user experience (UI/UX) testing with dementia caregivers as part of an iterative design process. Testing of caregiver’s reaction to technical and content-related aspects of the system was conducted with 31 caregivers. The thematic analysis revealed three themes for technical aspects (logical flow, suggestions on features, innovative resource) and two themes for content aspects (s...
Badain Jaran Desert (BJD), characterized by extremely arid climate and tallest sand dunes in the ... more Badain Jaran Desert (BJD), characterized by extremely arid climate and tallest sand dunes in the world, is the second largest desert in China. Surprisingly, there are a large number of permanent lakes in this desert. At present, little is known about the composition and distribution of microbial communities in these desert lakes, which are an important bioresource and play a fundamental role in the elemental cycles of the lakes. In this study, the physicochemical characteristics and microbial communities of water samples from 15 lakes in BJD were comparatively investigated. The results showed that the lakes were rich in Na+, Cl-, CO32- and HCO3- while Ca2+ and Mg2+ were scarce, with pH 8.52-10.27 and salinity 1.05-478.70 g/L. Bacteria dominated exclusively in low saline lakes (salinity < 50 g/L) while archaea were predominant in hypersaline lakes (salinity > 250 g/L), which abundance increased along salinity gradient linearly. Genera Flavobacterium, Synechocystis and Roseobacter from phyla Bacteroidetes, Cyanobacteria, Alphaproteobacteria were the major members in low saline lakes whereas Halomonas, Aliidiomarina and Halopelagius from Gammaproteobacteria and Euryarchaeota were abundant in moderately saline lakes (salinity 50-250 g/L). The hypersaline lakes were predominated by extreme halophiles such as Halorubrum, Halohasta and Natronomonas from Euryarchaeota. The correlation among the microbes in the lakes was mainly positive, suggesting they can survive in the harsh environments through synergistic interactions. Statistical analyses indicated that physicochemical characteristics rather than spatial factors shaped the microbial communities in the desert lakes. The pH was the most important environmental factor controlling alpha diversity, while salinity was the major driver determining microbial community structure in BJD lakes. In contrast, geographic factors had no significant impact on the microbial community compositions.
The reclamation of mine dump is largely centered on the role played by microorganisms. However, t... more The reclamation of mine dump is largely centered on the role played by microorganisms. However, the succession of microbial community structure and function in ecological restoration of the mine soils is still poorly understood. In this study, soil samples with different stacking time were collected from the dump of an iron mine in China and the physicochemical characteristics and microbial communities of these samples were comparatively investigated. The results showed that the fresh bare samples had the lowest pH, highest ion concentration, and were the most deficient in nutrients while the acidity and ion concentration of old bare samples decreased significantly, and the nutritional conditions improved remarkably. Vegetated samples had the weakest acidity, lowest ion concentration, and the highest nutrient concentration. In the fresh mine soils, the iron/sulfur-oxidizers such as Acidiferrobacter and Sulfobacillus were dominant, resulting in the strongest acidity. Bacteria from ge...
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
Modern day advancements in electrical engineering especially power generation and management has ... more Modern day advancements in electrical engineering especially power generation and management has enabled the path for More Electrical Aircrafts (MEAs) and hybrid propulsion systems. The electrical power generation in aerospace system is in itself an isolated micro grid with ac and dc components operating in either series or parallel or in hybrid mode. Uninterrupted and stable operation of these systems is of utmost importance. Known stability methods based on Lyapunov are difficult to implement as generalized on-line stability assessment procedure for such complex power network. In this paper a detailed and systematic small signal stability analysis of a More Electric Aircraft electrical power generation system is presented based on the eigen value analysis. The effect of different control algorithms on the MEE/MEA power network stability is studied using the proposed method. Also, it is shown that the stability is improved by using optimal gain feed-forward information of dc-bus currents. The stability matrix for the whole operating regime is developed and the stability margin variation for different operating conditions and control variations is presented. The efficacy of the estimated stability margin for MEE/MEA power network is verified using an Opal-RT Virtual test bed for all the control configurations.
Abstract Acidophiles play a vital catalytic role in the formation of acid mine drainage (AMD). In... more Abstract Acidophiles play a vital catalytic role in the formation of acid mine drainage (AMD). In this study, acidophilic communities in a stream, two lakes and five ponds in Nanshan Mine, Anhui Province, China were comparatively investigated. Among the three types of AMDs, the stream which originated from a rock wall had the strongest acidity (pH 2.30–2.42), while the ponds (pH 2.35–2.60) formed in mine dump and the two large-scale AMD lakes (pH 2.66–3.05) were less acidic. The chemolithotrophic iron-oxidizer Leptospirillum dominated at the stream starting point with the lowest pH and highest Fe content. However, with streamflow, pH increased and Fe concentration decreased dramatically, and the dominance of Leptospirillum was replaced by the less acid-resistant iron-oxidizer Ferrovum. In contrast to the stream, prokaryotic communities in the ponds were mostly dominated by chemoheterotrophic Acidiphilium because of the abundant organic matter from surrounding mine waste. Both chemolithotrophic Ferrovum and chemoheterotrophic Acidiphilium were abundant in the AMD lakes, which may form a symbiotic relationship around the carbon cycle. Statistical analyses indicated that pH was the predominant environmental factor influencing the prokaryotic communities. As for the eukaryotic communities, the microeukaryotes in the stream were mostly uncultured groups. Both photoautotrophic algae Chrysonebula and chemoheterotrophic fungi were abundant in the ponds, while the two AMD lakes were only dominated by photoautotrophic algae Coccomyxa and Ochromonas.
ABSTRACT The analytical proof showing that output voltage droop characteristics of parallel-conne... more ABSTRACT The analytical proof showing that output voltage droop characteristics of parallel-connected DC-DC power converters are only appropriate for limited applications is presented. Because power converters are very seldom identical, near-uniform current-sharing without additional control can be achieved only when paralleled power converters have similar characteristics and behave like ideal current sources. This can be achieved at the expense of poor voltage regulation. As an alternative, a current-sharing control technique, which requires no remote sensing, is proposed. This technique ensures uniform or designated current distribution throughout specified load range. A control circuit module is independently implemented without any preliminary knowledge or any circuit modification of the source power converters
The Zambia Defence Force adopted the Standards-Based Management and Recognition approach to impro... more The Zambia Defence Force adopted the Standards-Based Management and Recognition approach to improve the quality of the HIV-related services at its health facilities. This quality improvement intervention relies on comprehensive, detailed assessment tools to communicate and verify adherence to national standards of care, and to test and implement changes to improve performance. A quasi-experimental evaluation of the intervention was conducted at eight Zambia Defence Force primary health facilities (four facilities implemented the intervention and four did not). Data from three previous analyses are combined to assess the effect of Standards-Based Management and Recognition on three domains: facility readiness to provide services; observed provider performance during antiretroviral therapy (ART) and antenatal care consultations; and provider perceptions of the work environment. Facility readiness scores for ART improved on four of the eight standards at intervention sites, and one standard at comparison sites. Facility readiness scores for prevention of mother-to-child transmission (PMTCT) of HIV increased by 15 percentage points at intervention sites and 7 percentage points at comparison sites. Provider performance improved significantly at intervention sites for both ART services (from 58 to 84%; P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.01) and PMTCT services (from 58 to 73%; P = 0.003); there was no significant change at comparison sites. Providers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; perceptions of the work environment generally improved at intervention sites and declined at comparison sites; differences in trends between study groups were significant for eight items. A standards-based approach to quality improvement proved effective in supporting healthcare managers and providers to deliver ART and PMTCT services in accordance with evidence-based standards in a health system suffering from staff shortages.
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Papers by Joseph Banda