635 research outputs found
EXPERIMENTAL AND MODELING STUDY OF PARTICULATE MATTER OXIDATION UNDER LOADING CONDITIONS FOR A SCR CATALYST ON A DIESEL PARTICULATE FILTER
The heavy-duty diesel engines use a Diesel Oxidation Catalyst (DOC), a Catalyzed Particulate Filter (CPF), a Selective Catalytic Reduction (SCR) with urea injection and a Ammonia Oxidation Catalyst (AMOX), to meet the US EPA 2010/2013 particulate matter (PM) and NOx emission standards. However, it is not possible to achieve the 2015 California low NOx standards with this arrangement. Hence, there is a need to improve the existing aftertreatment system. This can be achieved by coating the SCR catalyst on a diesel particulate filter (DPF), thus combining the PM filtration and NOx reduction functionality into a single device. This reduces the overall volume/weight of the system and provides opportunity for packaging flexibility and improved thermal management along with the possibility of higher NOx reduction with a downstream SCR system.
The SCR catalyst on a DPF used in this study is known as a SCRFÂŪ which was supplied by Johnson Matthey and Corning. Previous research on the CPF and SCRFÂŪ at MTU highlighted that the reactivity of PM retained in the CPF and SCRFÂŪ is higher during loading conditions compared to passive oxidation conditions i.e. when the flow rate of PM entering the CPF or SCRFÂŪ is higher in loading conditions compared to the low flow rate and higher PM reaction rate during passive oxidation conditions. A 2013 Cummins ISB engine with a DOC-SCRFÂŪ arrangement was used to perform twelve tests (eight tests without urea injection and four tests with urea injection) in order to determine the NO2 assisted passive oxidation performance of the SCRFÂŪ under loading conditions with and without urea injection. The primary focus of this study was to carry out Loading Tests with and without Urea injection and measure species concentrations, PM mass retained, exhaust flowrates, substrate temperature distributions, pressure drop across the filter, and to determine the kinetics of NO2 assisted PM oxidation under loading conditions and compare it with kinetics under passive oxidation conditions.
The NO2 assisted passive oxidation performance of the SCRFÂŪ was experimentally studied by running the engine at 2400 RPM and four different loads at nominal and reduced rail pressure for 5.5 hours in two stages of loading. These conditions were intended to span the SCRFÂŪ inlet temperatures in the range of 264-364oC and inlet NO2 concentrations in the range of 52-120 ppm. Four conditions out of these eight conditions were repeated with the injection of urea in the form of diesel exhaust fluid at a target ammonia to NOx ratio of 1.0 to investigate both the NOx reduction performance, as well as the effect of urea on the NO2 assisted passive oxidation performance.
From the conclusions of the study based on the experimental data, it was found that the cumulative percentage of PM oxidized in the SCRFÂŪ increases with the increase in engine load due to higher SCRFÂŪ temperatures and NO2 concentrations. On average, the reactions rates with urea injection during loading conditions in the SCRFÂŪ are 25% lower compared to the reaction rates without urea injection. The reactivity of PM under loading conditions with and without urea injection is higher compared to the reactivity of PM under passive oxidation with and without urea injection. For a lumped PM oxidation model, a higher pre-exponential for NO2 assisted oxidation is needed for loading as compared to passive oxidation conditions. It was not possible to determine the kinetics of NO2 assisted oxidation of PM under loading conditions from the experimental data using a standard Arrhenius model which lead to the development of a different model for PM oxidation.
A PM oxidation model was developed based on the shrinking core model which keeps the identity of the incoming PM masses in the SCRFÂŪ as compared to SCR-F model being developed at MTU which is lumped model for PM oxidation. The PM oxidation model was calibrated to simulate PM oxidation in the SCRFÂŪ with a single set of kinetics under wide range of conditions including loading and passive oxidation conditions. The reaction rate results from the PM oxidation model were then applied to the SCR-F model to simulate the pressure drop across SCRFÂŪ and the PM retained in the SCRFÂŪ for the loading conditions used in this study. The SCR-F model was calibrated using experimental data from Loading Tests w/o Urea to simulate the PM retained within Âą2 g and pressure drop across SCRFÂŪ within Âą0.5 kPa of the experimental data at the end of the test. The calibrated SCR-F model was also used to estimate the cake, wall and channel pressure drop and the PM retained in the cake and wall for the Loading Tests w/o Urea to check the integrity of experimental data and the consistency of the model.
The NO2 assisted kinetics for PM oxidation in the SCRFÂŪ without urea injection using the SCR-F model resulted in an activation energy of 96 kJ/gmol and pre-exponential factor of 2.6 m/K-s for the cake and 1.8 m/K-s for the wall. An analysis of the results from the SCR-F model suggests that for all the conditions, 84-92% of the total PM retained was in the PM cake layer and the oxidation in the PM cake layer accounted for 72-84% of the total PM mass oxidized during loading
A Characterization of Absolutely Minimum Attaining operators
We study the spectral properties of positive absolutely minimum attaining operators defined on infinite dimensional complex Hilbert spaces and using that derive a characterization theorem for such type of operators. We construct several examples and discuss some of the properties of this class. Also, we extend this characterization theorem for general absolutely minimum attaining operators by means of the polar decomposition theorem
A Quality Improvement project to initiate the Confusion Assessment Method (CAM) delirium screening tool at a Skilled Nursing Facility and Rehabilitation Center in East Tennessee.
A Quality Improvement project to initiate the Confusion Assessment Method (CAM) delirium screening tool at a Skilled Nursing Facility and Rehabilitation Center in East Tennessee -- by S. Joseph Jadav, Doctor of Nursing Practice Candidate at East Tennessee State University.
Purpose/Aims: The aim of this project is to implement a delirium screening protocol in a skilled nursing and rehabilitation facility which will aid in early detection of signs and symptoms of delirium in older adults. This early detection followed by an early intervention can help reduce costs and decrease mortality rates with better outcomes.
Processes: A CAM screening is conducted on each patient (male & female) for delirium for a period of four weeks. Data collection will comprise of the number of patients assessed and the total number of positive and negative delirium cases. It was determined that the proposed activity is not research involving human subjects according to United States Department of Health and Human Services (DHHS) regulations by the universityâs Institutional Review Board (IRB).
Results: The project is currently in the data collection phase.
Limitations: Refusal to participate either by the patient or family in the screening.
Conclusions: While nearly 80% of delirium cases in an acute care setting go undetected or undiagnosed, this project to implement a delirium screening protocol in a skilled nursing facility is even more imperative in early detection and early intervention
āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠ āŠāŦāŠāŠ°āŠūāŠĪāŦ āŠĻāŠĩāŠēāŠāŠĨāŠūāŠĻāŠū āŠļāŠāŠĶāŠ°āŦāŠāŠŪāŠūāŠ
āŠĩāŠŋāŠķāŦāŠ°āŦāŠĩāŠŪāŠūāŠ āŠ
āŠĻāŦāŠ āŠļāŠāŠļāŦāŠāŦāŠĪāŠŋāŠ āŠāŠĶāŦāŠāŠĩāŦ āŠ
āŠĻāŦ āŠĻāŠūāŠķ āŠŠāŠūāŠŪāŦ. āŠŠāŠ°āŠāŠĪāŦ āŠāŠūāŠ°āŠĪāŦāŠŊ āŠļāŠāŠļāŦāŠāŦāŠĪāŠŋ āŠāŠāŦ āŠļāŠĶāŦāŠāŠĨāŦ āŠŠāŦāŠĪāŠūāŠĻāŦāŠ āŠĪāŦāŠ āŠ
āŠĻāŦ āŠŠāŠ°āŠāŠŠāŠ°āŠū āŠāŠūāŠģāŠĩāŠĪāŦ āŠāŠĩāŦ āŠāŦ. āŠāŠūāŠģāŠĻāŦ āŠĨāŠŠāŠūāŠāŦ āŠĪāŦāŠĻāŦ āŠĄāŠāŠūāŠĩāŦ āŠķāŠāŦ āŠĻāŠĨāŦ āŠāŦ āŠĪāŦāŠĻāŦ āŠĻāŦāŠāŦāŠķāŠūāŠĻ āŠāŠ°āŦ āŠķāŠāŦ āŠĻāŠĨāŦ. āŠāŠūāŠģāŠĻāŦ āŠĨāŠŠāŠūāŠāŦ āŠĪāŦāŠĻāŦ āŠĄāŠāŠūāŠĩāŦ āŠķāŠāŦ āŠĻāŠĨāŦ āŠāŦ āŠĪāŦāŠĻāŦ āŠĻāŦāŠāŠķāŠūāŠĻ āŠāŠ°āŦ āŠķāŠāŦ āŠĻāŠĨāŦ. āŠŠāŠ°āŠāŠĪāŦ, āŠŠāŠ°āŠŋāŠĩāŠ°āŦāŠĪāŠĻāŠĻāŠū āŠ āŠāŠŪāŠūāŠĻāŠūāŠŪāŠūāŠ āŠŊāŦāŠāŦāŠŊ āŠđāŠāŠūāŠ°āŠūāŠĪāŦāŠŪāŠ āŠŠāŠ°āŠŋāŠĩāŠ°āŦāŠĪāŠĻ āŠāŠĩāŦ āŠĪāŦ āŠāŠ°āŦāŠ°āŦ āŠāŦ. āŠĪāŦ āŠ āŠāŠŠāŠĢāŦ āŠāŠŠāŠĢāŠū āŠĩāŠūāŠ°āŠļāŠūāŠĻāŦ āŠķāŦāŠ§āŦāŠ§ āŠļāŦāŠĩāŠ°āŦāŠŠāŦ āŠāŠūāŠģāŠĩāŦ āŠķāŠāŦāŠķāŦāŠ. āŠĩāŠŋāŠķāŦāŠ°āŦāŠĩāŠĻāŦ āŠ
āŠĻāŦāŠ āŠļāŠāŠļāŦāŠāŦāŠĪāŠŋāŠ āŠŠāŦāŠĪāŠūāŠĻāŠū āŠĩāŠūāŠ°āŠļāŠūāŠĻāŦ āŠāŠūāŠģāŠĩāŦ āŠ°āŠūāŠāŠĩāŠū āŠŪāŠūāŠāŦ āŠĪāŠĨāŠū āŠĪāŦāŠĻāŦāŠ āŠļāŠāŠ°āŠāŦāŠ·āŠĢ āŠāŠ°āŠĩāŠū āŠŪāŠūāŠāŦ āŠāŠūāŠĪ āŠāŠūāŠĪāŠĻāŠū āŠŠāŦāŠ°āŠŊāŠĪāŦāŠĻāŦ āŠāŠ°āŠĪāŦ āŠ°āŠđāŦ āŠāŦ. āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦ āŠāŠ§āŦāŠĻāŠŋāŠāŠĪāŠūāŠĻāŠū āŠĻāŠūāŠŪāŦ āŠēāŦāŠĢāŦ āŠĻ āŠēāŠūāŠāŦ āŠĪāŦ āŠŪāŠūāŠāŦ āŠĪāŠĨāŠū āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŠū āŠļāŠāŠ°āŠāŦāŠ·āŠĢ āŠ
āŠ°āŦāŠĨāŦ āŠ
āŠĻāŦāŠ āŠŠāŦāŠ°āŠŊāŠĪāŦāŠĻāŦ āŠĨāŠ āŠ°āŠđāŦāŠŊāŠū āŠāŦ. āŠāŠūāŠ°āŠĪ āŠ
āŠĻāŦ āŠĪāŦāŠĻāŦ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦāŠ āŠāŦāŠāŦāŠ āŠŪāŦāŠēāŦāŠŊāŠūāŠāŠāŠĻ āŠĻ āŠĨāŠūāŠŊ, āŠāŠŠāŠĢāŦ āŠļāŠūāŠāŠļāŦāŠāŦāŠĪāŠŋāŠ āŠĩāŠūāŠ°āŠļāŦ āŠĩāŠ§āŦ āŠļāŠŪāŦāŠ§āŦāŠ§ āŠŽāŠĻāŦ āŠ
āŠĻāŦ āŠĩāŠ°āŦāŠĪāŠŪāŠūāŠĻ āŠāŠ§āŦāŠĻāŠŋāŠ āŠļāŠŪāŠŊāŠĻāŦ āŠāŠĄāŠ
āŠļāŠ°āŦ āŠĪāŦāŠĻāŦ āŠĻ āŠļāŦāŠŠāŠ°āŦāŠķāŦ āŠĪāŦāŠĩāŠū āŠŠāŦāŠ°āŠŊāŠĪāŦāŠĻ āŠŠāŦāŠ°āŦāŠĩāŠāŠĻāŠū āŠāŠķāŠŊāŠĨāŦ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦāŠ āŠ§āŠūāŠ°āŦāŠŪāŠŋāŠ, āŠāŠ§āŦāŠŊāŠŪāŠŋāŠ āŠ
āŠĻāŦ āŠŽāŦāŠ§āŦāŠ§āŠŋāŠ āŠĪāŠĨāŠū āŠļāŠūāŠāŠļāŦāŠāŦāŠĪāŠŋāŠ āŠķāŦāŠ§āŦāŠ§ āŠļāŦāŠĩāŠ°āŦāŠŠ āŠŠāŦāŠ°āŠāŠāŦ āŠĪāŦāŠĩāŦ āŠŠāŦāŠ°āŠŊāŠĪāŦāŠĻ āŠĨāŠūāŠŊ āŠĪāŦ āŠāŠ°āŦāŠ°āŦ āŠāŦ. āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŠū āŠķāŦāŠ§āŦāŠ§ āŠļāŦāŠĩāŠ°āŦāŠŠāŠĻāŦ āŠŠāŠūāŠ â āŠŠāŠĩāŠŋāŠĪāŦāŠ° āŠ°āŦāŠŠāŦ āŠŠāŦāŠ°āŠāŠ āŠāŠ°āŠĩāŠū āŠŪāŠūāŠāŦ āŠļāŠūāŠŪāŠūāŠāŠŋāŠ āŠ
āŠĻāŦ āŠ§āŠūāŠ°āŦāŠŪāŠŋāŠ āŠāŦāŠ·āŦāŠĪāŦāŠ°āŠĻāŠūāŠ āŠ
āŠĻāŦāŠ āŠļāŠāŠāŠ āŠĻāŠūāŠĪāŦāŠŪāŠ āŠāŦāŠ·āŦāŠĪāŦāŠ°āŦ āŠāŠūāŠŪ āŠāŠ°āŦ āŠ°āŠđāŦāŠŊāŠūāŠ āŠđāŦāŠŊ āŠĪāŦāŠŊāŠūāŠ°āŦ āŠļāŠūāŠđāŠŋāŠĪāŦāŠŊāŠāŠūāŠ° āŠāŦ āŠļāŠ°āŦāŠāŠ āŠāŦāŠŪ āŠāŦāŠŠ āŠŽāŦāŠļāŦ? āŠ§āŠ°āŦāŠŪāŠĻāŦ āŠāŦāŠŪ āŠļāŠūāŠđāŠŋāŠĪāŦāŠŊāŠŪāŠūāŠ āŠŠāŠĢ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦāŠ āŠļāŠāŠĩāŠ°āŦāŠ§āŠĻ āŠļāŠāŠ°āŠāŦāŠ·āŠĢ āŠŊāŦāŠāŦāŠŊ āŠ°āŦāŠĪāŦ āŠĨāŠūāŠŊ. āŠāŦāŠāŠū āŠāŦāŠŊāŠūāŠēāŦ â āŠŪāŠūāŠĻāŦāŠŊāŠĪāŠūāŠ āŠĶāŦāŠ° āŠāŠ°āŦ āŠķāŦāŠ§āŦāŠ§ āŠļāŦāŠĩāŠ°āŦāŠŠāŦ āŠĪāŦāŠĻāŦ āŠŠāŦāŠ°āŠāŠ āŠāŠ°āŦ āŠāŠŠāŠĢāŠū āŠļāŠūāŠāŠļāŦāŠāŦāŠĪāŠŋāŠ āŠĩāŠūāŠ°āŠļāŠūāŠĻāŦ āŠĩāŠ§āŦāŠĻāŦ āŠĩāŠ§āŦ āŠļāŠŪāŦāŠ§āŦāŠ§ āŠāŠ°āŠĩāŠūāŠĻāŠū āŠķāŦāŠ§āŦāŠ§ āŠđāŦāŠĪāŦāŠĨāŦ āŠāŠūāŠ°āŠĪāŦāŠŊ āŠļāŠ°āŦāŠāŠ āŠŠāŦāŠĪāŠūāŠĻāŠū āŠļāŠūāŠđāŠŋāŠĪāŦāŠŊāŠĻāŦāŠ āŠļāŠ°āŦāŠāŠĻ āŠāŠ°āŠĪāŦ āŠ°āŠđāŦāŠŊāŦ āŠāŦ āŠ
āŠĻāŦ āŠĪāŠĪāŦāŠāŠūāŠēāŦāŠĻ āŠŠāŦāŠ°āŠāŠūāŠĩāŦ āŠāŦāŠēāŠĪāŦ āŠāŦāŠēāŠĪāŦ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦ āŠĻāŠŋāŠ°āŦāŠŠāŠĪāŦ āŠāŠĩāŦāŠŊāŦ āŠāŦ. āŠŠāŦāŠ°āŠļāŦāŠĪāŦāŠĪ āŠķāŦāŠ§ āŠāŠūāŠ°āŦāŠŊāŠĻāŦ āŠŽāŦ āŠāŠāŠĄāŠŪāŠūāŠ āŠĩāŠŋāŠāŠūāŠāŠŋāŠĪ āŠāŠ°āŦāŠŊāŦāŠ āŠāŦ. āŠŠāŦāŠ°āŠĨāŠŪ āŠāŠāŠĄāŠŪāŠūāŠ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŦ āŠĩāŠŋāŠāŠūāŠĩāŠĻāŠūāŠĻāŦ āŠĩāŠŋāŠļāŦāŠĪāŠūāŠ°āŠĨāŦ āŠŠāŦāŠ°āŠāŠ āŠāŠ°āŠĩāŠūāŠŪāŠūāŠ āŠāŠĩāŦ āŠāŦ. āŠķāŦāŠ§āŠāŠūāŠ°āŦāŠŊāŠĻāŠū āŠŽāŦāŠāŠū āŠāŠāŠĄāŠŪāŠūāŠ āŠāŦāŠāŠ°āŠūāŠĪāŦ āŠĻāŠĩāŠēāŠāŠĨāŠūāŠĻāŦ āŠāŠūāŠ°āŠĪāŦāŠŊāŠĪāŠūāŠĻāŠū āŠļāŠāŠĶāŠ°āŦāŠāŠŪāŠūāŠ āŠĪāŠŠāŠūāŠļāŠĩāŠūāŠĻāŦ āŠāŠŠāŠāŦāŠ°āŠŪ āŠāŦ
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