Constructing the "Best" Reliability Data for the Job

Modern business and technical decisions are based on the results of analyses. When considering assessments using "reliability data", the concern is how long a system will continue to operate as designed. Generally, the results are only as good as the data used. Ideally, a large set of pass/fail tests or observations to estimate the probability of failure of the item under test would produce the best data. However, this is a costly endeavor if used for every analysis and design. Developing specific data is costly and time consuming. Instead, analysts rely on available data to assess reliability. Finding data relevant to the specific use and environment for any project is difficult, if not impossible. Instead, we attempt to develop the "best" or composite analog data to support our assessments. One method used incorporates processes for reviewing existing data sources and identifying the available information based on similar equipment, then using that generic data to derive an analog composite. Dissimilarities in equipment descriptions, environment of intended use, quality and even failure modes impact the "best" data incorporated in an analog composite. Once developed, this composite analog data provides a "better" representation of the reliability of the equipment or component can be used to support early risk or reliability trade studies, or analytical models to establish the predicted reliability data points. Data that is more representative of reality and more project specific would provide more accurate analysis, and hopefully a better final decision

Flight-based chemical characterization of biomass burning aerosols within two prescribed burn smoke plumes

Biomass burning represents a major global source of aerosols impacting direct radiative forcing and cloud properties. Thus, the goal of a number of current studies involves developing a better understanding of how the chemical composition and mixing state of biomass burning aerosols evolve during atmospheric aging processes. During the Ice in Clouds Experiment-Layer Clouds (ICE-L) in the fall of 2007, smoke plumes from two small Wyoming Bureau of Land Management prescribed burns were measured by on-line aerosol instrumentation aboard a C-130 aircraft, providing a detailed chemical characterization of the particles. After ~2–4 min of aging, submicron smoke particles, produced primarily from sagebrush combustion, consisted predominantly of organics by mass, but were comprised primarily of internal mixtures of organic carbon, elemental carbon, potassium chloride, and potassium sulfate. Significantly, the fresh biomass burning particles contained minor mass fractions of nitrate and sulfate, suggesting that hygroscopic material is incorporated very near or at the point of emission. The mass fractions of ammonium, sulfate, and nitrate increased with aging up to ~81–88 min and resulted in acidic particles. Decreasing black carbon mass concentrations occurred due to dilution of the plume. Increases in the fraction of oxygenated organic carbon and the presence of dicarboxylic acids, in particular, were observed with aging. Cloud condensation nuclei measurements suggested all particles >100 nm were active at 0.5% water supersaturation in the smoke plumes, confirming the relatively high hygroscopicity of the freshly emitted particles. For immersion/condensation freezing, ice nuclei measurements at −32 °C suggested activation of ~0.03–0.07% of the particles with diameters greater than 500 nm

Water activity and activation diameters from hygroscopicity data - Part I: Theory and application to inorganic salts

International audienceA method is described that uses particle hygroscopicity measurements, made with a humidified tandem differential mobility analyzer (HTDMA), to determine solution water activity as a function of composition. The use of derived water activity data in computations determining the ability of aerosols to serve as cloud condensation nuclei (CCN) is explored. Results for sodium chloride and ammonium sulfate are shown in Part I. The methodology yields solution water activities and critical dry diameters for ammonium sulfate and sodium chloride in good agreement with previously published data. The approach avoids the assumptions required for application of simplified and modified Köhler equations to predict CCN activity, most importantly, knowledge of the molecular weight and the degree of dissociation of the soluble species. Predictions of the dependence of water activity on the mass fraction of aerosol species are sensitive to the assumed dry density, but predicted critical dry diameters are not

Poster 118 Is a Clinical Measure of Upper Limb Reaction Time Predictive of Lower Limb Neuromuscular Function?

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147067/1/pmr2s209b.pd

Ice Initiation by Aerosol Particles: Measured and Predicted Ice Nuclei Concentrations versus Measured Ice Crystal Concentrations in an Orographic Wave Cloud

The initiation of ice in an isolated orographic wave cloud was compared with expectations based on ice nucleating aerosol concentrations and with predictions from new ice nucleation parameterizations applied in a cloud parcel model. Measurements of ice crystal number concentrations were found to be in good agreement both with measured number concentrations of ice nuclei feeding the clouds and with ice nuclei number concentrations determined from the residual nuclei of cloud particles collected by a counterflow virtual impactor. Using lognormal distributions fitted to measured aerosol size distributions and measured aerosol chemical compositions, ice nuclei and ice crystal concentrations in the wave cloud were reasonably well predicted in a 1D parcel model framework. Two different empirical parameterizations were used in the parcel model: a parameterization based on aerosol chemical type and surface area and a parameterization that links ice nuclei number concentrations to the number concentrations of particles with diameters larger than 0.5 μm. This study shows that aerosol size distribution and composition measurements can be used to constrain ice initiation by primary nucleation in models. The data and model results also suggest the likelihood that the dust particle mode of the aerosol size distribution controls the number concentrations of the heterogeneous ice nuclei, at least for the lower temperatures examined in this case

Observation of playa salts as nuclei in orographic wave clouds

During the Ice in Clouds Experiment-Layer Clouds (ICE-L), dry lakebed, or playa, salts from the Great Basin region of the United States were observed as cloud nuclei in orographic wave clouds over Wyoming. Using a counterflow virtual impactor in series with a single-particle mass spectrometer, sodium-potassium-magnesium-calcium-chloride salts were identified as residues of cloud droplets. Importantly, these salts produced similar mass spectral signatures to playa salts with elevated cloud condensation nuclei (CCN) efficiencies close to sea salt. Using a suite of chemical characterization instrumentation, the playa salts were observed to be internally mixed with oxidized organics, presumably produced by cloud processing, as well as carbonate. These salt particles were enriched as residues of large droplets (>19 μm) compared to smaller droplets (>7 μm). In addition, a small fraction of silicate-containing playa salts were hypothesized to be important in the observed heterogeneous ice nucleation processes. While the high CCN activity of sea salt has been demonstrated to play an important role in cloud formation in marine environments, this study provides direct evidence of the importance of playa salts in cloud formation in continental North America has not been shown previously. Studies are needed to model and quantify the impact of playas on climate globally, particularly because of the abundance of playas and expected increases in the frequency and intensity of dust storms in the future due to climate and land use changes

Water activity and activation diameters from hygroscopicity data - Part II: Application to organic species

International audienceA method has been developed for using particle hygroscopicity measurements made with a humidified tandem differential mobility analyzer (HTDMA) to determine water activity as a function of solute weight percent. In Part I, the method was tested for particles composed of sodium chloride and ammonium sulfate. Here, we report results for several atmospherically-relevant organic species: glutaric acid, malonic acid, oxalic acid and levoglucosan. Predicted water activities for aqueous dicarboxylic acid solutions are quite similar in some cases to published estimates and the simplified predictions of Köhler theory, while in other cases substantial differences are found, which we attribute primarily to the semivolatile nature of these compounds that makes them difficult to study with the HTDMA. In contrast, estimates of water activity for levoglucosan solutions compare very well with recently-reported measurements and with published data for aqueous glucose and fructose solutions. For all studied species, the critical dry diameters active at supersaturations between 0.2 and 1% that are computed with the HTDMA-derived water activities are generally within the experimental error (~20%) estimated in previously-published direct measurements using cloud condensation nuclei counters. For individual compounds, the variations in reported solution water activity lead to uncertainties in critical dry diameters of 5-25%, not significantly larger than the uncertainty in the direct measurements. To explore the impact of these uncertainties on modeled aerosol-cloud interactions, we incorporate the variations in estimates of solution water activities into the description of hygroscopic growth of aerosol particles in an adiabatic parcel model and examine the impact on the predicted drop number concentrations. For the limited set of initial conditions examined here, we find that the uncertainties in critical dry diameters for individual species lead to 0-21% changes in drop number concentration, with the largest effects at high aerosol number concentrations and slow updraft velocities. Ammonium sulfate, malonic acid and glutaric acid have similar activation behavior, while glutaric acid and levoglucosan are somewhat less hygroscopic and lead to lower drop number concentrations; sodium chloride is the most easily activated compound. We explain these behaviors in terms of a parameter that represents compound hygroscopicity, and conclude that this parameter must vary by more than a factor of 2 to induce more than a 15% change in activated drop number concentrations. In agreement with earlier studies, our results suggest that the number concentration of activated drops is more sensitive to changes in the input aerosol size and number concentrations and the applied updraft velocity than to modest changes in the aerosol composition and hygroscopic properties

Accuracy of Clinical Techniques for Evaluating Lower Limb Sensorimotor Functions Associated With Increased Fall Risk

BackgroundIn prior work, laboratoryâ based measures of hip motor function and ankle proprioceptive precision were critical to maintaining unipedal stance and fall/fallâ related injury risk. However, the optimal clinical evaluation techniques for predicting these measures are unknown.ObjectiveTo evaluate the diagnostic accuracy of common clinical maneuvers in predicting laboratoryâ based measures of frontal plane hip rate of torque development (HipRTD) and ankle proprioceptive thresholds (AnkPRO) associated with increased fall risk.DesignProspective, observational study.SettingBiomechanical research laboratory.ParticipantsA total of 41 older subjects (aged 69.1 ± 8.3 years), 25 with varying degrees of diabetic distal symmetric polyneuropathy and 16 without.AssessmentsClinical hip strength was evaluated by manual muscle testing (MMT) and lateral plank time, defined as the number of seconds that the laterally lying subject could lift the hips from the support surface. Foot/ankle evaluation included Achilles reflex and vibratory, proprioceptive, monofilament, and pinprick sensations at the great toe.Main Outcome MeasuresHipRTD, abduction and adduction, using a custom wholeâ body dynamometer. AnkPRO determined with subjects standing using a foot cradle system and a staircase series of 100 frontal plane rotational stimuli.ResultsPearson correlation coefficients (r) and receiver operator characteristic (ROC) curves revealed that LPT correlated more strongly with HipRTD (r/P = 0.61/1.0°.ConclusionsLPT is a more effective measure of HipRTD than MMT. Similarly, clinical vibratory sense and monofilament testing are effective measures of AnkPRO, whereas clinical proprioceptive sense is not.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146801/1/pmrj331.pd

Impoundment increases methane emissions in Phragmites‐invaded coastal wetlands

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Sanders‐DeMott, R., Eagle, M., Kroeger, K., Wang, F., Brooks, T., Suttles, J., Nick, S., Mann, A., & Tang, J. Impoundment increases methane emissions in Phragmites‐invaded coastal wetlands. Global Change Biology, 28(15), (2022): 4539– 4557. https://doi.org/10.1111/gcb.16217.Saline tidal wetlands are important sites of carbon sequestration and produce negligible methane (CH4) emissions due to regular inundation with sulfate-rich seawater. Yet, widespread management of coastal hydrology has restricted tidal exchange in vast areas of coastal wetlands. These ecosystems often undergo impoundment and freshening, which in turn cause vegetation shifts like invasion by Phragmites, that affect ecosystem carbon balance. Understanding controls and scaling of carbon exchange in these understudied ecosystems is critical for informing climate consequences of blue carbon restoration and/or management interventions. Here, we (1) examine how carbon fluxes vary across a salinity gradient (4–25 psu) in impounded and natural, tidally unrestricted Phragmites wetlands using static chambers and (2) probe drivers of carbon fluxes within an impounded coastal wetland using eddy covariance at the Herring River in Wellfleet, MA, United States. Freshening across the salinity gradient led to a 50-fold increase in CH4 emissions, but effects on carbon dioxide (CO2) were less pronounced with uptake generally enhanced in the fresher, impounded sites. The impounded wetland experienced little variation in water-table depth or salinity during the growing season and was a strong CO2 sink of −352 g CO2-C m−2 year−1 offset by CH4 emission of 11.4 g CH4-C m−2 year−1. Growing season CH4 flux was driven primarily by temperature. Methane flux exhibited a diurnal cycle with a night-time minimum that was not reflected in opaque chamber measurements. Therefore, we suggest accounting for the diurnal cycle of CH4 in Phragmites, for example by applying a scaling factor developed here of ~0.6 to mid-day chamber measurements. Taken together, these results suggest that although freshened, impounded wetlands can be strong carbon sinks, enhanced CH4 emission with freshening reduces net radiative balance. Restoration of tidal flow to impounded ecosystems could limit CH4 production and enhance their climate regulating benefits.This project was supported by USGS-NPS Natural Resources Preservation Program #2021-07, U.S. Geological Survey Coastal & Marine Hazards and Resources Program and the USGS Land Change Science Program's LandCarbon program, and NOAA National Estuarine Research Reserve Science Collaborative NA14NOS4190145. R Sanders-DeMott was supported by a USGS Mendenhall Fellowship and partnership with Restore America's Estuaries