4,496 research outputs found

    Icing flight research: Aerodynamic effects of ice and ice shape documentation with stereo photography

    Get PDF
    Aircraft icing flight research was performed in natural icing conditions. A data base consisting of icing cloud measurements, ice shapes, and aerodynamic measurements is being developed. During research icing encounters the icing cloud was continuously measured. After the encounter, the ice accretion shapes on the wing were documented with a stereo camera system. The increase in wing section drag was measured with a wake survey probe. The overall aircraft performance loss in terms of lift and drag coefficient changes was obtained by steady level speed/power measurements. Selective deicing of the airframe components was performed to determine their contributions to the total drag increase. Engine out capability in terms of power available was analyzed for the iced aircraft. It was shown that the stereo photography system can be used to document ice shapes in flight and that the wake survey probe can measure increases in wing section drag caused by ice. On one flight, the wing section drag coefficient (c sub d) increased approximately 120 percent over the uniced baseline at an aircraft angle of attack of 6 deg. On another flight, the aircraft darg coefficient (c sub d) increased by 75 percent over the uniced baseline at an aircraft lift coefficient (C sub d) of 0.5

    One Work Analysis, Two Domains: A Display Information Requirements Case Study

    Get PDF
    d observations, among other techniques. Given the time and resources required, we examine how to generalize a work domain analysis technique, namely the hybrid Cognitive Task Analysis (hCTA) method across two domains in order to generate a common set of display information requirements. The two domains of interest are field workers troubleshooting low voltage distribution networks and telecommunication problems. Results show that there is a high degree of similarity between the two domains due to their service call nature, particularly in tasking and decision-making. While the primary differences were due to communication protocols and equipment requirements, the basic overall mission goals, functions, phases of operation, decision processes, and situation requirements were very similar. A final design for both domains is proposed based on the joint requirements

    (Un)principled principals, (un)principled agents: The differential effects of managerial civil service reforms on corruption in developing and OECD countries

    Get PDF
    Do management practices have similar anticorruption effects in OECD and developing countries? Despite prominent cautions against “New Zealand” reforms which enhance managerial discretion in developing countries, scholars have not assessed this question statistically. Our article addresses this gap through a conjoint experiment with 6,500 public servants in three developing countries and one OECD country. Our experiment assesses Weberian relative to managerial approaches to recruitment, job stability, and pay. We argue that in developing countries with institutionalized corruption and weak rule of law—yet not OECD countries without such features—“unprincipled” principals use managerial discretion over hiring, firing, and pay to favor “unprincipled” bureaucratic agents who engage in corruption. Our results support this argument: managerial practices are associated with greater bureaucratic corruption in our surveyed developing countries, yet have little effect in our OECD country. Alleged “best practices” in public management in OECD countries may thus be “worst practices” in developing countries

    Temporal Trends in Incidence, Sepsis-Related Mortality, and Hospital-Based Acute Care After Sepsis.

    Get PDF
    OBJECTIVES: A growing number of patients survive sepsis hospitalizations each year and are at high risk for readmission. However, little is known about temporal trends in hospital-based acute care (emergency department treat-and-release visits and hospital readmission) after sepsis. Our primary objective was to measure temporal trends in sepsis survivorship and hospital-based acute care use in sepsis survivors. In addition, because readmissions after pneumonia are subject to penalty under the national readmission reduction program, we examined whether readmission rates declined after sepsis hospitalizations related to pneumonia. DESIGN AND SETTING: Retrospective, observational cohort study conducted within an academic healthcare system from 2010 to 2015. PATIENTS: We used three validated, claims-based approaches to identify 17,256 sepsis or severe sepsis hospitalizations to examine trends in hospital-based acute care after sepsis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: From 2010 to 2015, sepsis as a proportion of medical and surgical admissions increased from 3.9% to 9.4%, whereas in-hospital mortality rate for sepsis hospitalizations declined from 24.1% to 14.8%. As a result, the proportion of medical and surgical discharges at-risk for hospital readmission after sepsis increased from 2.7% to 7.8%. Over 6 years, 30-day hospital readmission rates declined modestly, from 26.4% in 2010 to 23.1% in 2015, driven largely by a decline in readmission rates among survivors of nonsevere sepsis, and nonpneumonia sepsis specifically, as the readmission rate of severe sepsis survivors was stable. The modest decline in 30-day readmission rates was offset by an increase in emergency department treat-and-release visits, from 2.8% in 2010 to a peak of 5.4% in 2014. CONCLUSIONS: Owing to increasing incidence and declining mortality, the number of sepsis survivors at risk for hospital readmission rose significantly between 2010 and 2015. The 30-day hospital readmission rates for sepsis declined modestly but were offset by a rise in emergency department treat-and-release visits

    Experimental Area of the CERN Antiproton Decelerator

    Get PDF
    The CERN Antiproton Decelerator will deliver low energy beams to four experimental beam-lines installed within the acceleratorcircumference. The limited space available imposes tight constraints on the topology of the beam-lines needed by the experimental devices. In this paper, the general layout of the experimental area is reviewed. Furthermore, a discussion of the so-called measurement line for tests and AD beam property measurements is included along with remarks on the optics of the reverse injection of protons, to be used for the commissioning

    Reliability of Krylov Subspace Methods - A Practical Perspective

    Get PDF
    • …
    corecore