53 research outputs found
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Improvements in the LLNL objective analysis scheme for deriving forcing fields for single-column models using ARM data
The objective analysis method use for deriving Single-Column Model (SCM) forcing fields with ARM data (Leach, et al., 1996) is undergoing continual improvement. Several improvements were identified at the SCM Workshop held at LLNL in April 1996. These include incorporating large-scale analyses in the objective analysis, and time-filtering input data streams
Description of the ARM Operational Objective Analysis System
This report describes the ARM (Atmospheric Radiation Measurement) operational variational objective analysis system. It is currently used to process the data collected from the ARM Intensive Operational Periods (IOPs) for driving and evaluating physical parameterizations in climate models. The analysis system was originally developed by Zhang and Lin (1997) at State University of New York at Stony Brook and was migrated to the Lawrence Livermore National Laboratory (LLNL) as the ARM operational objective analysis system in May 1999. In contrast with previous objective analysis (e.g., Barnes, 1964; O'Brien, 1970; Lin and Johnson, 1996), the ARM objective analysis used the constrained variational analysis method developed by Zhang and Lin (1997), in which the atmospheric state variables are forced to satisfy the conservation of mass, heat, moisture, and momentum through a variational technique. The purpose of this technical report is to provide an overview of the constrained variational analysis method, the architecture of the objective analysis system, along with in-depth information on running the variational analysis codes
Water sorption isotherms and hysteresis of cement paste at moderately high temperature, up to 80 °C
The constitutive models of concrete often consider water desorption isotherms to be near-equilibrium and significantly affected by moderately high temperature, 40–80◦C, typically through microstructural changes. However literature data suggest that adsorption, not desorption, is near-equilibrium and moderate temperatures do not cause microstructural changes. This work supports the latter theory, through dynamic vapor sorption experiments on cement paste at 20–80◦C. Samples were pre-conditioned at 60% relative humidity and 20◦C, and isotherms were measured for several humidity ranges and testing rates. The results, corroborated by classical DFT simulations, indicate that adsorption is near-equilibrium and mostly unaffected by temperature, whereas desorption is out-of-equilibrium due to the ink-bottle effect at high humidity, and interlayer water at low humidity. Starting from the second cycle, desorption at higher temperatures features a shift of the cavitation pressure and overall a smaller hysteresis. A conceptual model of pore-specific temperature-dependent hysteresis is proposed to qualitatively explain the results
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The AERI/GOES Retrievals Versus Radiosondes for Driving SCMs
Single-Column Models (SCMs) require observations to provide suitable initial and boundary conditions. To meet this need, the Atmospheric Radiation Measurement (ARM) program conducts Intensive Observing Periods (IOPs) to provide 3-hourly radiosondes and other observations. However, such high-frequency sonde launches can be expensive. Therefore, the ARM program can only support a couple IOPs each year with each one lasting 2-4 weeks. In order to reduce the need for high-frequency sonde launches and to potentially expand the periods available for SCM simulations, they have conducted a study using the Atmospheric Emitted Radiance Interferometer (AERI) and Geostationary Operational Environmental Satellite (GOES) temperature and moisture retrievals, instead of radiosondes, in the ARM variational analysis system (Zhang and Lin, 1997; Zhang et al., 2000) to derive the large-scale forcing terms for driving SCMs during the March 1999 IOP. They have compared the large-scale forcing and associated SCM simulations for various combinations of data sources used in the variational analysis
Microscopy techniques for determining water-cement (w/c) ratio in hardened concrete: A round-robin assessment
Water to cement (w/c) ratio is usually the most important parameter specified in concrete design and is sometimes the subject of dispute when a shortfall in concrete strength or durability is an issue. However, determination of w/c ratio in hardened concrete by testing is very difficult once the concrete has set. This paper presents the results from an inter-laboratory round-robin study organised by the Applied Petrography Group to evaluate and compare microscopy methods for measuring w/c ratio in hardened concrete. Five concrete prisms with w/c ratios ranging from 0.35 to 0.55, but otherwise identical in mix design were prepared independently and distributed to 11 participating petrographic laboratories across Europe. Participants used a range of methods routine to their laboratory and these are broadly divided into visual assessment, measurement of fluorescent intensity and quantitative backscattered electron microscopy. Some participants determined w/c ratio using more than one method or operator. Consequently, 100 individual w/c ratio determinations were collected, representing the largest study of its type ever undertaken. The majority (81%) of the results are accurate to within ± 0.1 of the target mix w/c ratios, 58% come to within ± 0.05 and 37% are within ± 0.025. The study shows that microscopy-based methods are more accurate and reliable compared to the BS 1881-124 physicochemical method for determining w/c ratio. The practical significance, potential sources of errors and limitations are discussed with the view to inform future applications
Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study
Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030
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Automated Application of Calibration Factors on Telemetered Data
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, NevadaA long standing problem in telemetry post processing is the application of correct calibration factors to telemetered data generated on a system which has had a history of hardware changes. These calibration problems become most exacerbated when old test data is being examined and there is uncertainty as to hardware configuration at the time of the test. In this paper a mechanism for introducing a high degree of reliability in the application of calibration factors is described in an implementation done for Brilliant Pebbles Flight Experiment Three (FE-3).International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection
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The ARM SCM ontercomparison study - overview and preliminary results for case 1
The Single-Column Model (SCM) Working Group in the Atmospheric Radiation Measurement (ARM) Program has begun a series of SCM Intercomparison case studies to evaluate the adequacy of the forcing data sets and the progress of SCM formulations. There are nine modeling groups participating, which include eight SCMs: Ghan (PNNL), Randall/Cripe (CSU), Somerville/Iacobellis (Scripps/UCSD), Klein (NOAA/GFDL), Lohmann (Dalhousie), Stenchikov/Robock (Maryland, Rutgers), Zhang/Xie (SUNY Stony Brook), Sud/Wlaker (NASA/GSFC), and one 2-D cloud-resolving model: Xu (CSU). The first case study addresses the prescription of advective forcing, the methods used to derive SCM forcing terms, and the methods used to estimate surface flux forcing. Details of the SCM Intercomparison procedures are given elsewhere (Cederwall, et al., 1998)
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Automated Binding of Attributes to Telemetry Data
International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, NevadaAn automated method is described for binding attributes to extracted data from a telemetry stream. These attributes can be used by post processing utilities to facilitate efficient analysis. A practical implementation of such a scheme is described.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection
Experimental analysis of green roof detention characteristics
Green roofs may make an important contribution to urban stormwater management. Rainfall-runoff models are required to evaluate green roof responses to specific rainfall inputs. The roof's hydrological response is a function of its configuration, with the substrate – or growing media – providing both retention and detention of rainfall. The objective of the research described here is to quantify the detention effects due to green roof substrates, and to propose a suitable hydrological modelling approach. Laboratory results from experimental detention tests on green roof substrates are presented. It is shown that detention increases with substrate depth and as a result of increasing substrate organic content. Model structures based on reservoir routing are evaluated, and it is found that a one-parameter reservoir routing model coupled with a parameter that describes the delay to start of runoff best fits the observed data. Preliminary findings support the hypothesis that the reservoir routing parameter values can be defined from the substrate's physical characteristics
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