10,160 research outputs found
Reservation Wages-Measurement and Determinants: Evidence from the KMP Survey
This paper investigates the difficulties in measuring reservation wages, models the determinants of reservation wages, and compares reservation wages with predicted wages. Data is drawn from the Khayelitsha/Mitchell's Plain (KMP) survey. Certain factors (e.g. education, labour market status, household income and duration of unemployment) are significant in explaining variation in reservation wages. Importantly, a person's position in the labour market is not as a result of his/her reservation wage. Rather, reservation wages are a function of his/her labour market status: while those in wage-employment report a reservation wage based more on perceived labour market value, those in unemployment report a reservation wage influenced strongly by subsistence requirements. This study concludes that voluntary unemployment does not exist in KMP, with people in general reporting reservation wages well below what they could expect to earn.
Oral health beliefs and behaviors of nurse and nurse practitioner students using the HU-DBI inventory: An opportunity for oral health vicarious learning
Background: Oral health access to care issues are resulting in curricular changes to train nursing students as oral health educators and providers. However, little data are available concerning their personal oral health beliefs/behaviors. The study purpose was to gather information from nurse and nurse practitioner students regarding their oral health beliefs and behaviors.
Methods: Using the Hiroshima University Dental Behavioural Inventory (HU-DBI), survey data were gathered from nurse and nurse practitioner students as well as dental hygiene students as controls concerning their oral health beliefs and behaviors.
Results: Mean HU-DBI scores were higher among nurse practitioner than nursing students, indicating more positive beliefs/behaviors, but both were lower than dental hygiene students. Both nurse and nurse practitioner students reported significantly fewer dental visits and some poorer hygiene practices than controls. Additionally, nursing students were more likely to believe that their teeth were worsening despite brushing.
Conclusions: Assessment of personal oral health beliefs/behaviors should occur early in nursing education with mentoring so that optimal modeling can positively impact patients’ oral health. Oral health education opportunities within and among disciplines are discussed
LOX/hydrocarbon rocket engine analytical design methodology development and validation. Volume 1: Executive summary and technical narrative
During the past three decades, an enormous amount of resources were expended in the design and development of Liquid Oxygen/Hydrocarbon and Hydrogen (LOX/HC and LOX/H2) rocket engines. A significant portion of these resources were used to develop and demonstrate the performance and combustion stability for each new engine. During these efforts, many analytical and empirical models were developed that characterize design parameters and combustion processes that influence performance and stability. Many of these models are suitable as design tools, but they have not been assembled into an industry-wide usable analytical design methodology. The objective of this program was to assemble existing performance and combustion stability models into a usable methodology capable of producing high performing and stable LOX/hydrocarbon and LOX/hydrogen propellant booster engines
Multimodal hybrid powerplant for unmanned aerial systems (UAS) robotics
Most UAS propulsion systems currently utilize either Internal Combustion Engines (ICE) or Electric Motor (EM) prime movers. ICE are favoured for aircraft use due to the superior energy density of fuel compared to batteries required for EM, however EM have several significant advantages. A major advantage of EM is that they are inherently self starting have predictable response characteristics and well developed electronic control systems. EMs are thus very easy to adapt to automatic control, whereas ICE have more complex control response and an auxiliary starting motor is required for automated starting. This paper presents a technique for determining the performance, feasibility and effectiveness of powerplant hybridisation for small UAS. A Hybrid Powerplant offers the possibility of a radical improvement in the autonomy of the aircraft for various tasks without sacrificing payload range or endurance capability. In this work a prototype Aircraft Hybrid Powerplant (AHP) was designed, constructed and tested. It is shown that an additional 35% continuous thrust power can be supplied from the hybrid system with an overall weight penalty of 5%, for a given UAS. Dynamometer and windtunnel results were obtained to validate theoretical propulsion load curves. Using measured powerplant data and an assumed baseline airframe performance characteristic, theoretical endurance comparisons between hybrid and non-hybrid powerplants were determined. A flight dynamic model for the AHP was developed and validated for the purposes of operational scenario analysis. Through this simulation it is shown that climb rates can be improved by 56% and endurance increased by 13%. The advantages of implementing a hybrid powerplant have been baselined in terms of payload range and endurance. Having satisfied these parameters, a whole new set of operational possibilities arises which cannot be performed by non-self-starting ICE only powered aircraft. A variety of autonomous robotic aircraft tasks enabled by the hybrid powerplant is discussed
X ray microscope/telescope test and alignment
The tasks performed by the Center for Applied Optics (CAO) in support of the Normal Incidence Multilayer X-Ray Optics Program are detailed. The Multi-Spectral Solar Telescope Array (MSSTA) was launched on a Terrier-boosted Black Brant sounding rocket from White Sands Missile Range on 13 May 1991. High resolution images of the sun in the soft x ray to extreme ultraviolet (EUV) regime were obtained with normal-incidence Cassegrain, Ritchey-Chretien, and Herschelian telescopes mounted in the sounding rocket. MSSTA represents the first use of multilayer optics to study a very broad range of x ray and EUV solar emissions. Energy-selective properties of multilayer-coated optics allow distinct groups of emission lines to be isolated in the solar corona and transition region. Features of the near and far coronal structures including magnetic loops of plasmas, coronal plumes, coronal holes, faint structures, and cool prominences are visible in these images. MSSTA successfully obtained unprecedented information regarding the structure and dynamics of the solar atmosphere in the temperature range of 10(exp 4)-10(exp 7) K. The performance of the MSSTA has demonstrated a unique combination of ultra-high spatial resolution and spectral differentiation by use of multilayer optics
Tele-autonomous systems: New methods for projecting and coordinating intelligent action at a distance
There is a growing need for humans to perform complex remote operations and to extend the intelligence and experience of experts to distant applications. It is asserted that a blending of human intelligence, modern information technology, remote control, and intelligent autonomous systems is required, and have coined the term tele-autonomous technology, or tele-automation, for methods producing intelligent action at a distance. Tele-automation goes beyond autonomous control by blending in human intelligence. It goes beyond tele-operation by incorporating as much autonomy as possible and/or reasonable. A new approach is discussed for solving one of the fundamental problems facing tele-autonomous systems: The need to overcome time delays due to telemetry and signal propagation. New concepts are introduced called time and position clutches, that allow the time and position frames between the local user control and the remote device being controlled, to be desynchronized respectively. The design and implementation of these mechanisms are described in detail. It is demonstrated that these mechanisms lead to substantial telemanipulation performance improvements, including the result of improvements even in the absence of time delays. The new controls also yield a simple protocol for control handoffs of manipulation tasks between local operators and remote systems
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