917 research outputs found
Inlet/nacelle/exhaust system integration for the QCSEE propulsion systems
The key features of the integrated propulsion systems developed for short haul aircraft are discussed including the high Mach number, fixed geometry, near sonic inlet, the variable area nozzles, thrust reversing systems, and aircraft accessory location. The roles and interplay of each element are considered and comparisons are made with conventional state-of-the-art technology
Analysis and documentation of QCSEE (Quiet Clean Short-haul Experimental Engine) over-the-wing exhaust system development
A static scale model test program was conducted in the static test area of the NASA-Langley 9.14- by 18.29 m(30- by 60-ft) Full-Scale Wind Tunnel Facility to develop an over-the-wing (OTW) nozzle and reverser configuration for the Quiet Clean Short-Haul Experimental Engine (QCSEE). Three nozzles and one basic reverser configuration were tested over the QCSEE takeoff and approach power nozzle pressure ratio range between 1.1 and 1.3. The models were scaled to 8.53% of QCSEE engine size and tested behind two 13.97-cm (5.5-in.) diameter tip-turbine-driven fan simulators coupled in tandem. An OTW nozzle and reverser configuration was identified which satisfies the QCSEE experimental engine requirements in terms of nozzle cycle area variation capability and reverse thrust level, and provides good jet flow spreading over a wing upper surface for achievement of high propulsive lift performance
The Case for Baccalaureate-Prepared Nurses
The nursing workforce plays a central role in our present health care system, and will likely have an even greater role in the future. Nurses already provide the vast majority of care to patients in hospitals, and so it should come as no surprise that the quality of nursing care affects patient outcomes. Over the past decade, studies have linked certain nursing characteristics—such as staffing levels, education, job satisfaction, and work environment—with better outcomes in hospitals. This Issue Brief adds to that evidence with a longitudinal study that links changes in nurse education with improvements in surgical patients’ survival. It also discusses how a more educated nurse workforce could fill a range of new roles in primary care, prevention, and care coordination as health reform is implemented
Energy efficient engine. Fan and quarter-stage component performance report
The fan configuration for the general Electric/NASA Energy Efficient Engine was selected following an extensive preliminary design study. The fan has an inlet radius ratio of 0.342 and a specific flowrate of 208.9 Kg/sec/sq. m (42.8 1bm/sec/sq. ft). The design corrected tip speed is 411.5 m/sec (1350 ft/sec) producing a bypass flow total-pressure ratio of 1.65 and a core flow total-pressure ratio of 1.6. The design bypass ratio is 6.8. The aerodynamic design point corresponds to the maximum climb power setting at Mach 0.8 and 10.67 Km (35,000 ft) altitude. The fully-instrumented fan component was tested in the Lynn Large Fan Test Facility in 1981. The overall performance results, reported herein, showed excellent fan performance with the fan meeting all of its component test goals of flow, efficiency and stall margin
COVID-19: Pathophysiology and implications for cystic fibrosis, diabetes and cystic fibrosis-related diabetes
The novel SARS-CoV-2 coronavirus (COVID-19) has become a global health crisis since its initial outbreak in Wuhan, China in December 2019. On January 30, 2020, the WHO recognized the COVID-19 outbreak as a Public Health Emergency, and on March 11, 2020, it was declared a pandemic. Although all age groups have been affected, patients with cystic fibrosis (CF) and patients with type 1 or type 2 diabetes have been categorized as highly vulnerable to SARS-CoV-2 infection. Thus far, studies have found that the incidence of SARS-CoV-2 in the CF population is lower than the general population. We review the underlying protective mechanisms which may reduce inflammation and lung damage in CF patients, thus decreasing their risk of severe COVID-19. While the effect of SARS-CoV-2 in those with diabetes related to CF is unknown, other forms of diabetes have been associated with more severe disease. To further understand the potential impact of SARS-CoV-2 in cystic fibrosis-related diabetes, we provide a comprehensive overview of the potential factors contributing to COVID-19 severity in other forms of diabetes, including direct viral effect on the pancreas and indirect effects related to hyperglycemia and immune dysregulation
Thermodynamic and transport property modeling in super critical water
Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2005.Includes bibliographical references.Supercritical water oxidation (SCWO) is a thermally-based, remediation and waste-treatment process that relies on unique property changes of water when water is heated and pressurized above its critical point. Above its critical point (374.1 ⁰C and 220.9 bar), water becomes gas-like and somewhat non-polar due to the decrease in density and disruption of the hydrogen-bond network. When oxidants and organic compounds are combined with supercritical water (SCW), they rapidly form a single phase, and these organics are quickly and completely oxidized to simple molecules including water and carbon dioxide. Laboratory research is currently being conducted in order to increase the level of understanding of key SCWO areas including reaction kinetics, corrosion, and salt-related phenomena and in order to develop realistic SCWO process and fluid-dynamic simulators. Understanding the phenomena in each of these areas requires accurate thermodynamic- and transport-property predictions. However, these often do not exist. Furthermore, available correlations are often used in operating regimes where they were not originally validated, thereby potentially reducing their accuracy. This thesis focuses on the development of accurate thermodynamic-property and diffusivity- transport-property models for use at typical SCWO operating conditions, namely 25 ⁰C =/< T =/< 650 ⁰C and 1 bar =/< P =/< 300 bar, along with the measurement of molecular diffusivity, an important transport-phenomena property. These models can be incorporated into simulation tools which are used to model SCWO processes or physically simulate the flow, kinetics, corrosion, salt nucleation, and salt precipitation inside SCWO reactors.(cont.) These large-scale SCWO simulations should ultimately lead to improved reactor designs which have less operating risk, appropriately sized reactors, optimized residence times, lower costs, fewer technical limitations, and increased destruction efficiencies. Thermodynamic-property research: Hard-sphere, volume-translated van der Waals equation of state (EOS) The hard-sphere, volume-translated van der Waals EOS is comprised of the semi-theoretical Carnahan-Starling expression that properly represents the molecular interactions between hard spheres and a simple van der Waals attraction term. It also utilizes volume translation to further improve high density predictions. The translation constant is determined by a fit to liquid and vapor coexistence density data while the Carnahan-Starling and van der Waals parameters are determined from widely available critical-point data. An analysis of several important thermodynamic properties (e.g., density, vapor pressure, and enthalpy) has been shown to fit within average deviations of 1-30% over a wide range of conditions for the selected components: ammonia, carbon dioxide, ethylene, methane, nitrogen, oxygen, and water.(cont.) Thermodynamic-property research: An analysis of EOS Zeno behavior The behavior of the "Zeno" (Z = PVIRT = 1) line has been examined in a collaborative project in order to investigate this recently rediscovered empirical regularity of fluids and to determine if such a regularity can be utilized to improve EOSs and their predictions. For a wide range of pure fluids, this contour of unit compressibility factor in the temperature-density plane has been empirically observed to be nearly linear (and arrow-like, thus "Zeno") from the Boyle temperature of the low density vapor to near the triple point in the liquid region. Although quantitative agreement between Zeno EOS predictions and experimental data is not exact, the general trends suggest that these EOS models adequately capture the dynamic balance that exists between repulsive and attractive forces along the Zeno line. In addition, molecular simulation of Zeno behavior showed good agreement with experimental data. Transport-property research: Measurement and modeling of molecular diffusivities The transport-property research consists of measuring molecular diffusivities at SCWO operating conditions using nuclear magnetic resonance (NMR) and validating diffusivity models with these experimental and previously published results. Self-diffusivities of pure supercritical water have been previously measured and published for a limited range of conditions, but accurate SCW binary-diffusivity data are extremely limited. For this reason, diffusivities of aqueous acetone mixtures have been measured at SCWO conditions using a novel, first-of-a-kind SCW/NMR flow system and the NMR spin-echo technique.(cont.) Experimental results are compared with predictions from kinetic-gas-theory models and hydrodynamic-theory correlations. For SCWO operating conditions, the Tracer Liu-Silva-Macedo (TLSM) and Mathur-Thodos correlations were found to provide the most accurate diffusivity predictions. The Mathur-Thodos correlation requires only critical constants and molecular weights and has an average absolute deviation (AAD) of 18% for supercritical-water self-diffusivities and supercritical tracer & infinitely dilute mutual diffusivities above 400 ⁰C. Similar results were obtained with the TLSM model (23% AAD for data above 400 ⁰C) which requires only molecular weights and two Lennard-Jones (LJ) 6-12 parameters for each pure component. Further improvement was made when mole-fraction- weighted experimental solute and LSM-provided water LJ parameters were used (20% AAD). As a result of the improved thermodynamic- and transport-property modeling capabilities along with the collection of additional aqueous supercritical diffusivities contained in this thesis, the SCWO community now has additional thermodynamic- and transport-property knowledge that leads to a greater understanding of key issues that impact the design and operation of SCWO technology.by Michael C. Kutney.Sc.D
Psychiatric Comorbidity and Greater Hospitalization Risk, Longer Length of Stay, and Higher Hospitalization Costs in Older Adults with Heart Failure
OBJECTIVES: To explore associations between psychiatric comorbidity and rehospitalization risk, length of hospitalization, and costs.
DESIGN: Cross‐sectional study of 1‐year hospital administrative data.
SETTING: Claims‐based study of older adults hospitalized in the United States.
PARTICIPANTS: Twenty‐one thousand four hundred twenty‐nine patients from a 5% national random sample of U.S. Medicare beneficiaries aged 65 and older, with at least one acute care hospitalization in 1999 with a Diagnostic‐Related Group of congestive heart failure.
MEASUREMENTS: The number of hospitalizations, mean length of hospital stay, and total hospitalization costs in calendar year 1999.
RESULTS: Overall, 15.8% of patients hospitalized for heart failure (HF) had a coded psychiatric comorbidity; the most commonly coded comorbid psychiatric disorder was depression (8.5% of the sample). Most forms of psychiatric comorbidity were associated with greater inpatient utilization, including risk of additional hospitalizations, days of stay, and hospitalization charges. Additional hospitalization costs associated with psychiatric comorbidity ranged up to $7,763, and additional days length of stay ranged up to 1.4 days.
CONCLUSION: Psychiatric comorbidity appears in a significant minority of patients hospitalized for HF and may affect their clinical and economic outcomes. The associations between psychiatric comorbidity and use of inpatient care are likely to be an underestimate, because psychiatric illness is known to be underdetected in older adults and in hospitalized medical patients
2,6,6-Trimethylcyclohexene-1-carbaldehyde oxime
In the crystal of the title compound C10H17NO, synthesized by the reaction of β-cyclocitral with hydroxylamine hydrochloride, inversion-related molecules are linked by a pair of O—H⋯N hydrogen-bonding interactions between the oxime functionalities, forming R
2
2(6) loops. The molecular conformation is stabilized by intramolecular methyl C—H⋯N interactions. The cyclohexene ring has the typical half-chair conformation
3-[4-(Dimethylamino)phenyl]-1-(4a,8-dimethyl-1,2,3,4,4a,5,6,8a-octahydronaphthalen-2-yl)prop-2-en-1-one
The title compound, C23H31NO, was semisynthesized from isocostic acid, isolated from the aerial part of Inula Viscosa (L) Aiton [or Dittrichia Viscosa (L) Greuter]. The cyclohexene ring has a half-chair conformation, whereas the cyclohexane ring displays a chair conformation. The dihedral angle between the latter ring and its substituent is 83.6 (7)°
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