347 research outputs found
Embedded Sensors and Controls to Improve Component Performance and Reliability Conceptual Design Report
The objective of this project is to demonstrate improved reliability and increased performance made possible by deeply embedding instrumentation and controls (I&C) in nuclear power plant (NPP) components and systems. The project is employing a highly instrumented canned rotor, magnetic bearing, fluoride salt pump as its I&C technology demonstration platform. I&C is intimately part of the basic millisecond-by-millisecond functioning of the system; treating I&C as an integral part of the system design is innovative and will allow significant improvement in capabilities and performance. As systems become more complex and greater performance is required, traditional I&C design techniques become inadequate and more advanced I&C needs to be applied. New I&C techniques enable optimal and reliable performance and tolerance of noise and uncertainties in the system rather than merely monitoring quasistable performance. Traditionally, I&C has been incorporated in NPP components after the design is nearly complete; adequate performance was obtained through over-design. By incorporating I&C at the beginning of the design phase, the control system can provide superior performance and reliability and enable designs that are otherwise impossible. This report describes the progress and status of the project and provides a conceptual design overview for the platform to demonstrate the performance and reliability improvements enabled by advanced embedded I&C
Is it dangerous? The role of an emotional visual search strategy and threatârelevant training in the detection of guns and knives
Counterâterrorism strategies rely on the assumption that it is possible to increase threat detection by providing explicit verbal instructions to orient people's attention to dangerous objects and hostile behaviours in their environment. Nevertheless, whether verbal cues can be used to enhance threat detection performance under laboratory conditions is currently unclear. In Experiment 1, student participants were required to detect a picture of a dangerous or neutral object embedded within a visual search display on the basis of an emotional strategy âis it dangerous?â or a semantic strategy âis it an object?â. The results showed a threat superiority effect that was enhanced by the emotional visual search strategy. In Experiment 2, whilst trainee police officers displayed a greater threat superiority effect than student controls, both groups benefitted from performing the task under the emotional than semantic visual search strategy. Manipulating situational threat levels (high vs. low) in the experimental instructions had no effect on visual search performance. The current findings provide new support for the languageâasâcontext hypothesis. They are also consistent with a dualâprocessing account of threat detection involving a verbally mediated route in working memory and the deployment of a visual template developed as a function of training
An Adaptive Framework for Selecting Environmental Monitoring Protocols to Support Ocean Renewable Energy Development
Offshore renewable energy developments (OREDs) are projected to become common in the United States over the next two decades. There are both a need and an opportunity to guide efforts to identify and track impacts to the marine ecosystem resulting from these installations. A monitoring framework and standardized protocols that can be applied to multiple types of ORED would streamline scientific study, management, and permitting at these sites. We propose an adaptive and reactive framework based on indicators of the likely changes to the marine ecosystem due to ORED. We developed decision trees to identify suites of impacts at two scales (demonstration and commercial) depending on energy (wind, tidal, and wave), structure (e.g., turbine), and foundation type (e.g., monopile). Impacts were categorized by ecosystem component (benthic habitat and resources, fish and fisheries, avian species, marine mammals, and sea turtles) and monitoring objectives were developed for each. We present a case study at a commercial-scale wind farm and develop a monitoring plan for this development that addresses both local and national environmental concerns. In addition, framework has provided a starting point for identifying global research needs and objectives for understanding of the potential effects of ORED on the marine environment
Impact of age norms and stereotypes on managers' hiring decisions of retirees
Purpose -Our study investigates the role of managers in the re-employment of early retirees and asks what the effect is of managersâ age norms and stereotypes on managersâ employment decisions.
Design/methodology/approach- A combination of a factorial study and a survey was conducted. First, information on the age norms and stereotypes was collected. Secondly, profiles of hypothetical retired job applicants were presented to the employers, who were asked to make a specific hiring decision. The information collected during both studies was combined in the analysis and multilevel models were estimated.
Findings -The results indicate that higher age norms result in a higher propensity to hire an early retiree. Stereotypes, by contrast, do not influence managersâ decisions. Early retireesâ chances for re-employment are also related to their own circumstances (physical appearance and relevant experience) and organisational forces, as they are hired when organisations face labour force shortages.
Research limitation / implications â with the use of vignettes study we deal with hypothetical hiring situation.
Originality value- Although the effect of age norms and age stereotypes has been often suggested, not much empirical evidence was presented to support this notion. Our study estimates the effect of age norms and stereotypes on hiring decision.
key words: bridge employment; early retirees; age norms; age stereotypes; multilevel models.
MsFLASH Participantsâ Priorities for Alleviating Menopausal Symptoms
Objective To describe self-reported menopausal symptom priorities and their association with demographics and other symptoms among participants in an intervention trial for vasomotor symptoms (VMS).
Methods Cross-sectional study embedded in the MsFLASH 02 trial, a three-by-two factorial design of yoga vs. exercise vs. usual activity and omega-3-fatty acid vs. placebo. At baseline, women (nâ=â354) completed hot flush diaries, a card sort task to prioritize symptoms they would most like to alleviate, and standardized questionnaires.
Results The most common symptom priorities were: VMS (nâ=â322), sleep (nâ=â191), concentration (nâ=â140), and fatigue (nâ=â116). In multivariate models, women who chose VMS as their top priority symptom (nâ=â210) reported significantly greater VMS severity (pâ=â0.004) and never smoking (pâ=â0.012), and women who chose sleep as their top priority symptom (nâ=â100) were more educated (pââ€â0.001) and had worse sleep quality (pâ<â0.001). ROC curves identified sleep scale scores that were highly predictive of ranking sleep as a top priority symptom.
Conclusions Among women entering an intervention trial for VMS and with relatively low prevalence of depression and anxiety, VMS was the priority symptom for treatment. A card sort may be a valid tool for quickly assessing symptom priorities in clinical practice and research
Methyl jasmonate effects on sugarbeet root responses to postharvest dehydration
Background Sugarbeet (Beta vulgaris L.) roots are stored under conditions that cause roots to dehydrate, which increases postharvest losses. Although exogenous jasmonate applications can reduce drought stress in intact plants, their ability to alleviate the effects of dehydration in postharvest sugarbeet roots or other stored plant products is unknown. Research was conducted to determine whether jasmonate treatment could mitigate physiological responses to dehydration in postharvest sugarbeet roots. Methods Freshly harvested sugarbeet roots were treated with 10 ”M methyl jasmonate (MeJA) or water and stored under dehydrating and non-dehydrating storage conditions. Changes in fresh weight, respiration rate, wound healing, leaf regrowth, and proline metabolism of treated roots were investigated throughout eight weeks in storage. Results Dehydrating storage conditions increased root weight loss, respiration rate, and proline accumulation and prevented leaf regrowth from the root crown. Under dehydrating conditions, MeJA treatment reduced root respiration rate, but only in severely dehydrated roots. MeJA treatment also hastened wound-healing, but only in the late stages of barrier formation. MeJA treatment did not impact root weight loss or proline accumulation under dehydrating conditions or leaf regrowth under non-dehydrating conditions. Both dehydration and MeJA treatment affected expression of genes involved in proline metabolism. In dehydrated roots, proline dehydrogenase expression declined 340-fold, suggesting that dehydration-induced proline accumulation was governed by reducing proline degradation. MeJA treatment altered proline biosynthetic and catabolic gene expression, with greatest effect in non-dehydrated roots. Overall, MeJA treatment alleviated physiological manifestations of dehydration stress in stored roots, although the beneficial effects were small. Postharvest jasmonate applications, therefore, are unlikely to significantly reduce dehydration-related storage losses in sugarbeet roots
Solid-state laser system for laser cooling of Sodium
We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with
up to 800 mW output power. The laser relies on sum-frequency generation from
two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a
doubly-resonant cavity. We obtain conversion efficiency as high as 2 W/W^2
after optimization of the cavity parameters. The output wavelength is tunable
over 60 GHz, which is sufficient to lock on the Sodium D2 line. The robustness,
beam quality, spectral narrowness and tunability of our source make it an
alternative to dye lasers for atomic physics experiments with Sodium atoms
Starfire Optical Range 3.5-m telescope adaptive optical system
A 941 channel, 1500 Hertz frame rate adaptive optical (AO) system has been installed and tested in the coude path of the 3.5m telescope at the USAF Research Laboratory Starfire Optical Range. This paper describes the design and measured performance of the principal components comprising this system and present sample results from the first closed-loop test of the system on stars and an artificial source simulator
Modern optical astronomy: technology and impact of interferometry
The present `state of the art' and the path to future progress in high
spatial resolution imaging interferometry is reviewed. The review begins with a
treatment of the fundamentals of stellar optical interferometry, the origin,
properties, optical effects of turbulence in the Earth's atmosphere, the
passive methods that are applied on a single telescope to overcome atmospheric
image degradation such as speckle interferometry, and various other techniques.
These topics include differential speckle interferometry, speckle spectroscopy
and polarimetry, phase diversity, wavefront shearing interferometry,
phase-closure methods, dark speckle imaging, as well as the limitations imposed
by the detectors on the performance of speckle imaging. A brief account is
given of the technological innovation of adaptive-optics (AO) to compensate
such atmospheric effects on the image in real time. A major advancement
involves the transition from single-aperture to the dilute-aperture
interferometry using multiple telescopes. Therefore, the review deals with
recent developments involving ground-based, and space-based optical arrays.
Emphasis is placed on the problems specific to delay-lines, beam recombination,
polarization, dispersion, fringe-tracking, bootstrapping, coherencing and
cophasing, and recovery of the visibility functions. The role of AO in
enhancing visibilities is also discussed. The applications of interferometry,
such as imaging, astrometry, and nulling are described. The mathematical
intricacies of the various `post-detection' image-processing techniques are
examined critically. The review concludes with a discussion of the
astrophysical importance and the perspectives of interferometry.Comment: 65 pages LaTeX file including 23 figures. Reviews of Modern Physics,
2002, to appear in April issu
Does proactive personality matter in leadership transitions? Effects of proactive personality on new leader identification and responses to new leaders and their change agendas
Despite the growing frequency of leadership transitions and their significant impact on team and organizational performance, little research has examined why and how teams develop an identification with a new leader or their subsequent receptiveness to the new leaderâs change initiatives. Drawing from the contrast and congruence effects and the theoretical perspectives of leader identification, this study empirically tests a model in which the congruence of new leadersâ and their teamsâ proactive personalities foster new leader identification, as well as the teamâs behavioral responses to the new leaderâs change agenda. This effect is strongest when the new leaderâs proactive personality is higher than that of the former leaderâs proactive personality (positive contrast). Our findings of a four-wave âbefore-and-afterâ transition survey of 155 hotel employees and 51 new leaders, achieved through polynomial regression analyses, proved very insightful. Essentially, we found that the congruence between a new leaderâs and his/her teamâs proactive personalities and the positive contrast between a former leaderâs and the new leaderâs proactive personalities enhanced new leader identification and the teamâs shared identification with the new leaderâs change agenda, and, thereby led the team to exhibit more behavioral engagement with, and voice behavior about, the new leaderâs change agenda
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