Synthetic Observations of the HI Line in SPH-Simulated Spiral Galaxies

Using the radiative transfer code Torus, we produce spectral-line cubes of the predicted HI profile from global SPH simulations of spiral galaxies. Torus grids the SPH galaxy using Adaptive Mesh Refinement, then applies a ray-tracing method to infer the HI profile along the line(s) of sight. The gridded galaxy can be observed from any direction, which enables us to model the observed HI profile for galaxies of any orientation. We can also place the observer inside the galaxy, to simulate HI observations taken from the Earth's position in the Milky Way.Comment: 4 pages, 2 figures, conference proceedings for "Panoramic Radio Astronomy: 1-2 Ghz Research on Galaxy Evolution" June 2-5, 2009 Groninge

Examining the stability derivatives of a compound helicopter

Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a conventional helicopter. One method to examine the flight dynamics of an aircraft is to create a linearised mathematical model of the aircraft and to investigate the stability derivatives of the vehicle. The aim of this paper is to examine the stability derivatives of a compound helicopter through a comparison with a conventional helicopter. By taking this approach, some stability, handling qualities and design issues associated with the compound helicopter can be identified. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter is a standard design, featuring a main rotor and a tail-rotor. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, whereas two propellers provide additional propulsive thrust as well as yaw control. The results highlight that the bare airframe compound helicopter would require a larger tailplane surface to ensure acceptable longitudinal handling qualities in forward flight. In addition, without increasing the size of the bare airframe compound helicopter’s vertical fin, the Dutch roll mode satisfies the ADS-33 level 1 handling qualities category for the majority of the flight envelope

Maneuverability assessment of a compound helicopter configuration

The compound helicopter design could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. The main benefit of the compound helicopter is its ability to reach speeds that significantly surpass those of the conventional helicopter. However, it is possible that the compound helicopter design can provide additional benefits in terms of maneuverability. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter features a standard helicopter design with a main rotor providing the propulsive and lifting forces, while a tail rotor, mounted at the rear of the aircraft, provides the yaw control. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, and two propellers provide additional axial thrust as well as yaw control. This study investigates the maneuverability of these two helicopter configurations using inverse simulation. The results predict that a compound helicopter configuration is capable of attaining greater load factors than its conventional counterpart, when flying a pullup–pushover maneuver. In terms of the accel–decel maneuver, the compound helicopter configuration is capable of completing the maneuver in a shorter time than the conventional helicopter, but at the expense of greater installed engine power. The addition of thrust compounding to the compound helicopter design reduces the pitch attitude required throughout the acceleration stage of the maneuver

Manoeuvrability assessment of a hybrid compound helicopter configuration

The compound helicopter design could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. The main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the compound helicopter design can provide additional benefits in terms of manoeuvrability. The paper features a conventional helicopter and a hybrid compound helicopter. The conventional helicopter features a standard helicopter design with a main rotor providing the propulsive and lifting forces, whereas a tail rotor, mounted at the rear of the aircraft provides the yaw control. The compound helicopter configuration, known as the hybrid compound helicopter, features both wing and thrust compounding. The wing offloads the main rotor at high speeds whereas two propellers provide additional axial thrust as well as yaw control. This study investigates the manoeuvrability of these two helicopter configurations using inverse simulation. The results predict that a hybrid compound helicopter configuration is capable of attaining greater load factors than its conventional counterpart, when flying a Pullup-Pushover manoeuvre. In terms of the Accel-Decel man oeuvre, the two helicopter configurations are capable of completing the manoeuvre in comparable time-scales. However, the addition of thrust compounding to the compound helicopter design reduces the pitch attitude required throughout the acceleration stage of the manoeuvre

Investigation of a Compound Helicopter Flying the Depart and Abort Mission Task Element

The next generation of rotorcraft will have to satisfy the appropriate handling qualities requirements before entering service. Many of these vehicles will operate at significantly greater speeds than the conventional helicopter and will therefore have different capabilities than current helicopters. Due to the different capabilities of the compound helicopter, it is possible that new Mission Task Elements (MTEs) need to be developed to assess the handling qualities of this type of helicopter. It is also possible that existing MTEs may be suitable without modification. Overall, it seems necessary to review the US Army’s current handling qualities specification, ADS-33, and determine the suitability of the current MTEs for compound vehicles. The broad aim of the paper is to assess the performance of compound helicopter during manoeuvring flight. More specifically, a simulation study of a compound helicopter flying the Depart and Abort ADS-33 Mission Task Element. There are two objectives: firstly the capabilities of the compound vehicle is compared with those of a conventional helicopter, and secondly, the suitability of the current Depart and Abort MTE, for compound vehicles, is assessed. The results of the research study highlight the capability of compound helicopters in low speed acceleration manoeuvres. These results can be used to redefine low speed acceleration manoeuvres in the new update to the ADS-33 specification. The results also indicate some information about the potential design issues with the compound helicopter

What Can We Learn From the Existing Evidence of the Business Case for Investments in Nursing Care: Importance of Content, Context, and Policy Environment

Decisions of health care institutions to invest in nursing care are often guided by mixed and conflicting evidence of effects of the investments on organizational function and sustainability. This paper uses new evidence generated through Interdisciplinary Nursing Quality Research Initiative (INQRI)-funded research and published in peer-reviewed journals, to illustrate where the business case for nursing investments stands and to discuss factors that may limit the existing evidence and its transferability into clinical practice. We conclude that there are 3 limiting factors: (1) the existing business case for nursing investments is likely understated due to the inability of most studies to capture spillover and long-run dynamic effects, thus causing organizations to forfeit potentially viable nursing investments that may improve long-term financial stability; (2) studies rarely devote sufficient attention to describing the content and the organization-specific contextual factors, thus limiting generalizability; and (3) fragmentation of the current health care delivery and payment systems often leads to the financial benefits of investments in nursing care accruing outside of the organization incurring the costs, thus making potentially quality-improving and cost-saving interventions financially unattractive from the organization\u27s perspective. The payment reform, with its emphasis on high-quality affordable patient-centered care, is likely to strengthen the business case for investments in nursing care. Methodologically rigorous approaches that focus on broader societal implications of investments in nursing care, combined with a thorough understanding of potential barriers and facilitators of nursing change, should be an integral part of future research and policy efforts

Executive Pay and Firm Performance: Methodological Considerations and Future Directions

This paper is an investigation of the pay-for-performance link in executive compensation. In particular we document main issues in the pay-performance debate and explain practical issues in setting pay as well as data issues including how pay is disclosed and how that has changed over time. We also provide a summary of the state of CEO pay levels and pay mix in 2009 using a sample of over 2,000 companies and describe main data sources for researchers. We also investigate what we believe to be at the root of fundamental confusion in the literature across disciplines – methodological issues. In exploring methodological issues, we focus on empirical specifications, causality, fixed-effects, first- differencing and instrumental variables issues. We then discuss two important but not yet well explored areas; international issues and compensation in nonprofits. We conclude by examining a series of research areas where further work can be done, within and across disciplines

Coping with Shocks and Shifts: The Multilateral Trading System in Historical Perspective

This paper provides a historical look at how the multilateral trading system has coped with the challenge of shocks and shifts. By shocks we mean sudden jolts to the world economy in the form of financial crises and deep recessions, or wars and political conflicts. By shifts we mean slow-moving, long-term changes in comparative advantage or shifts in the geopolitical equilibrium that force economies to undergo disruptive and potentially painful adjustments. We conclude that most shocks (financial crises and regional wars) have had relatively little effect on trade policy, but that shifts pose a greater challenge to the system of open, multilateral trade.

The knowledge-based software assistant

Where the Knowledge Based Software Assistant (KBSA) is now, four years after the initial report, is discussed. Also described is what the Rome Air Development Center expects at the end of the first contract iteration. What the second and third contract iterations will look like are characterized