Front-end Stage Design of a Two-stage Grid-tied PV Inverter

This study is the first demonstration of a continuous culture bio-catalysed iron oxidation and jarosite precipitation reactor using thermophilic archea, for use in hydrometallurgical process flow sheets. A two-stage continuous stirred tank reactor (CSTR) system comprised of two CSTRs, each with its own settler, was operated for biological iron oxidation and precipitation at 70°C. The two-stage design was to allow the growth of microorganisms that prefer various redox regimes. The bioreactors were inoculated with a mixed culture of extreme thermophilic iron oxidisers from genera Acidianus, Metallosphaera and Sulfolobus. The influent (pH 1.5) contained (g L-1) 15 Fe2+, 1.5 Cu, 1.5 Ni (all as sulfates), nutrients and trace elements. At a hydraulic retention time (HRT) of 6-7 h in each CSTR, the overall iron oxidation rate was 1.0±0.1 g L-1 h-1 and percent 97±2%. The pH values were 1.38±0.16 and 1.57±0.05, and redox potentials (Ag/AgCl reference) were474±47 mV and 575±1 mV, in CSTR1 and CSTR2, respectively. The percentages of influent Fe, Cu and Ni removed as precipitates from settlers were 52%, 0.46% and 0.03%, respectively. The precipitates were comprised of jarosite (100%), potassium jarosite being the dominant form (38-51%), followed by hydronium (30-35%), ammonium (13-18%) and sodium jarosites (6-9%). The precipitates had a sludge volume index of 5.8-19 mL g-1, indicating good settling properties facilitating easy removal through settling. The simultaneous and instantaneous addition of contaminants (g L-1: 2.0 Al, 0.05 As, 0.05 F, 0.2 Co, 5.0 Mg and 0.4 Mn), potentially contained in hydrometallurgical processing streams, into the influent decreased the iron oxidation (50% overall oxidation with HRT of 26-29 h in each CSTR) and jarosite content in precipitates (85-87%). In conclusion, the two-stage high-temperature CSTR system allowed iron oxidation and precipitation of the oxidised iron in the form of well settling jarosite with only minor loss of Cu and Ni via co-precipitation. However, the bioreactor performance was hampered by the introduction of other transition metals, fluoride and arsenic.

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Second Harmonic Current Reduction in Front-End DC−DC Converter for Two-Stage Single-Phase Photovoltaic Grid-Connected Inverter

IEEE Transactions on Power Electronics ◽

10.1109/tpel.2018.2877590 ◽

2019 ◽

Vol 34 (7) ◽

pp. 6399-6410 ◽

Cited By ~ 7

Author(s):

Shiqi Kan ◽

Xinbo Ruan ◽

Hao Dang ◽

Li Zhang ◽

Xinze Huang

Keyword(s):

Single Phase ◽

Second Harmonic ◽

Harmonic Current ◽

Two Stage ◽

Front End ◽

Grid Connected Inverter ◽

Current Reduction

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Two-Stage Design of Sequencing Studies for Testing Association with Rare Variants

Human Heredity ◽

10.1159/000328193 ◽

2011 ◽

Vol 71 (4) ◽

pp. 209-220 ◽

Cited By ~ 6

Author(s):

Fan Yang ◽

Duncan C. Thomas

Keyword(s):

Rare Variants ◽

Two Stage ◽

Stage Design ◽

Sequencing Studies ◽

Two Stage Design

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Two-Stage Single-Arm Trials Are Rarely Analyzed Effectively or Reported Adequately

JCO Precision Oncology ◽

10.1200/po.21.00276 ◽

2021 ◽

pp. 1813-1820

Author(s):

Michael J. Grayling ◽

Adrian P. Mander

Keyword(s):

Final Stage ◽

Interim Analysis ◽

Primary Outcome ◽

Point Estimate ◽

Two Stage ◽

Stage Design ◽

Patient Subgroup ◽

Future Studies ◽

Point Estimates ◽

Outcome Trial

PURPOSE Two-stage single-arm designs have historically been the most common design used in phase II oncology. They remain a mainstay today, particularly for trials in rare subgroups. Consequently, it is imperative such studies be designed, analyzed, and reported effectively. We comprehensively review such trials to examine whether this is the case. METHODS Oncology trials that used Simon's two-stage design over a 5-year period were identified and reviewed. They were evaluated for whether they reported sufficient design (eg, required sample size) and analysis (eg, CI) details. Articles that did not adjust their inference for the incorporation of an interim analysis were also reanalyzed. RESULTS Four-hundred twenty-five articles were included. Of these, just 47.5% provided the five components that ensure design reproducibility. Only 1.2% and 2.1% reported an adjusted point estimate or CI, respectively. Just 55.3% provided the final stage rejection bound, indicating many trials did not test a hypothesis for their primary outcome. Trial reanalyses suggested reported point estimates underestimated treatment effects and reported CIs were too narrow. CONCLUSION Key design details of two-stage single-arm trials are often unreported. Their inference is rarely performed such as to remove bias introduced by the interim analysis. These findings are particular alarming when considered against the growing trend in which nonrandomized trials make up a large proportion of all evidence on a treatment's effectiveness in a rare biomarker-defined patient subgroup. Future studies must improve the way they are analyzed and reported.

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