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24 results on '"Mack, W."'

7. A liquid water management strategy for PEM fuel cell stacks

Author

Mack W. Knobbe and Trung Van Nguyen

Subjects
Materials science, Waste management, Hydrogen, Renewable Energy, Sustainability and the Environment, business.industry, Flow (psychology), Energy Engineering and Power Technology, Proton exchange membrane fuel cell, chemistry.chemical_element, Power (physics), Management strategy, Stack (abstract data type), chemistry, Electrical and Electronic Engineering, Physical and Theoretical Chemistry, Process engineering, business, Power density, Ambient pressure
Abstract

Gas and water management are key to achieving good performance from a PEM fuel cell stack. Previous experimentation had found, and this experimentation confirms, that one very effective method of achieving proper gas and water management is the use of an Interdigitated flow field design. However, the results of a single fuel cell with an Interdigitated flow field could not be extended to a multi-cell stack because of the inability to establish uniform gas flow to each individual cell. Since the interdigitated flow field uses the flow of gas for excess water removal, a deficient flow of gas causes the cell to become flooded. To alleviate this problem of unequal gas distribution, a method of sequentially exhausting each individual cell was developed. This method controls each cell’s exhaust so that only one cell at any given time has an open exhaust port, thereby, ensuring gas will flow through that cell. By sequentially exhausting each cell, it will be ensured that the gas will flow to each cell and provide the water management necessary to achieve good performance. This was demonstrated in a three-cell PEM stack with interdigitated flow fields operating at ambient pressure and temperature on neat hydrogen and oxygen. The results showed that the use of sequential exhaust control improved the peak power from 0.26 W/cm2 per cell without exhaust control to 0.50 W/cm2 per cell, a doubling of the power density.

Published
2003
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20. Semiautomated UV Analysis of Caffeine in Aspirin–Phenacetin–Caffeine Tablets

Author

Mack W Overton, Larry L Alber, and Raymond S. Valentine

Subjects
Aspirin, Autoanalysis, Chloroform, Chromatography, Coefficient of variation, Bicarbonate, Phenacetin, Pharmaceutical Science, urologic and male genital diseases, female genital diseases and pregnancy complications, Solutions, Bicarbonates, chemistry.chemical_compound, chemistry, Caffeine, Methods, medicine, Spectrophotometry, Ultraviolet, Tablets, medicine.drug
Abstract

A semiautomated individual tablet assay was developed for caffeine in aspirin–phenacetin–caffeine formulations. Caffeine and phenacetin are extracted from the bicarbonate tablet solution with chloroform. The caffeine and some phenacetin are extracted from the chloroform with acid, and an additional chloroform wash of the acid phase removes any phenacetin. The caffeine is determined by UV spectroscopy in the acid at 266 nm. at a rate of 20 tablets/hr. The coefficient of variation for 10 determinations of one sample solution was 1.72. The difference in results between the NF XIII method and the proposed method, expressed as percent of declared, did not exceed 2.6% when 10 different products were analyzed.

Published
1973
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21. Synchronized moving pictures of patient and EEG

Author

Donald Withee, Mack W. Schwab, Robert S. Schwab, and Young Chew Chock

Subjects
Patients, medicine.diagnostic_test, business.industry, General Neuroscience, medicine, Humans, Electroencephalography, Computer vision, Neurology (clinical), Artificial intelligence, business
Published
1954
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