4,087 research outputs found
The broad emission-line region: the confluence of the outer accretion disc with the inner edge of the dusty torus
(Abridged) We investigate the observational characteristics of BLR geometries
in which the BLR clouds bridge the gap, both in distance and scale height,
between the outer accretion disc and the hot dust, forming an effective surface
of a "bowl". The gas dynamics are dominated by gravity, and we include the
effects of transverse Doppler shift, gravitational redshift and scale-height
dependent macro-turbulence. Our simple model reproduces many of the phenomena
observed in broad emission-line variability studies, including (i) the absence
of response in the core of the optical recombination lines on short timescales,
(ii) the enhanced red-wing response on short timescales, (iii) differences
between the measured delays for the HILs and LILs, and (iv) identifies
turbulence as a means of producing Lorentzian profiles (esp. for LILs) in low
inclination systems, and for suppressing significant continuum--emission-line
delays between the line wings and line core (esp. in LILs). A key motivation of
this work was to reveal the physical underpinnings of the reported measurements
of SMBH masses and their uncertainties. We find that SMBH masses derived from
measurements of the fwhm of the mean and rms profiles show the closest
correspondence between the emission lines in a single object, even though the
emission line fwhm is a more biased mass indicator with respect to inclination.
The predicted large discrepancies in the SMBH mass estimates between emission
lines at low inclination, as derived using the line dispersion, we suggest may
be used as a means of identifying near face-on systems. Our general results do
not depend on specific choices in the simplifying assumptions, but are in fact
generic properties of BLR geometries with axial symmetry that span a
substantial range in radially-increasing scale height supported by turbulence,
which then merge into the inner dusty TOR.Comment: 29 pages, 23 figures and 1 tabl
The Short- and Long-Term Effects of Child Abuse and Their Implications for the Suggested Length of Physical and Psychosocial Treatment Regimens
Child abuse is the physical, psychological, or neglectful maltreatment of a child by a caregiver. Intimate partner violence relates closely to child mistreatment. Children are not likely to disclose that their parent or guardian is abusing them. Child abuse may result in short-term consequences, long-term consequences, or death. Some negative outcomes of maltreatment include delinquency, mental health issues, physical problems, educational underachievement, and socioeconomic disparities. The cycle of mistreatment is when a parent who suffered abuse as a child is more likely to maltreat his or her own child. There are factors that protect from the consequences of mistreatment. Research evidence should inform practice as to how to assist victims of child abuse
Analysis of Working from Home vs Working at the Office, as a Construction Company in the Bay Area
In 2020, working from home has become an increasingly popular trend amongst construction offices across the Bay Area to combat the spread of COVID-19. This meant that employees who used to commute were now able to work from home. This paper analyzes the impacts working from home has on the productivity, work-life-balance, and overall well-being of a Bay Area construction office employees . A survey was issued to the estimating department of a large general contractor in the Bay Area, with the intent of finding the impact working from home had on the three aspects of working life, as previous listed. The survey was broken-out into three sections with the purpose of collecting quantitative and qualitative data, from a variety of questions, for each of the three aspects of working life. An analysis of the data collected in the survey reveals working from home has a positive effect on the working life of former commuters in the Bay Area construction industry. This paper brings new understanding and offers future research to the potential benefits and downfalls to working from home when compared to commuting to work every day
Load Modeling and Evaluation of LEDs for Hardware Test Bed Application
The lighting industry was revolutionized with the emergence of LED lighting. Over the last 15 years, LED lighting device sales and utilization have grown immensely. The growth and popularity of LEDs is due to improved operation of the device when compared to previous lighting technologies. Efficient performance of the device is critical due to the growth of global energy consumption.
As nonrenewable generation fuel is finite, utilities have begun the transition to renewable energy generation. Generation and distribution systems become inherently complex to comprehend and maintain with incorporation of emerging supply and load technologies. With the unprecedented growth of LED bulbs, there are concerns regarding the impact of their integration on power systems.
In determination of the effects, which LED bulb adoption posed within the power grid, investigation of this device as a grid-load was pursued. This thesis reviews existing studies pertaining to LEDs and power grid load modeling methodologies. Load modeling aids in establishing a balance between energy generation and consumption, comprehensively characterizing relationships between electrical generation, transmission, distribution, and loads.
Due to the complexities of large networked systems, device load models are constructed and aggregated in emulation of the interactive relationships throughout the power grid. This thesis includes a study of preestablished LED bulb ZIP load models and formulation of a component-based load model for improved characterization of a conventional LED lighting device. Load modeling was conducted with reference to the UTK HTB, for future integration and improved grid emulation.
Factors, such as shape, size, illumination, and the power rating of popular LED bulbs is examined. Through investigation of typical LED bulb topologies, a model is formulated, in representation of device behavior as a load. The established load model’s characteristics are tested with comparison to physical device operation in a laboratory environment.
The LED bulb component-based model is simulated under dynamic conditions in portrayal of device behavior under fault scenarios. An interactive interface is formulated for simulation of load behavior throughout grid level events. Detailed analysis of data and methods of implementation is provided, in characterization of the LED bulb’s load profile
Tuning the scattering length with an optically induced Feshbach resonance
We demonstrate optical tuning of the scattering length in a Bose-Einstein
condensate as predicted by Fedichev {\em et al.} [Phys. Rev. Lett. {\bf 77},
2913 (1996)]. In our experiment atoms in a Rb condensate are exposed to
laser light which is tuned close to the transition frequency to an excited
molecular state. By controlling the power and detuning of the laser beam we can
change the atomic scattering length over a wide range. In view of laser-driven
atomic losses we use Bragg spectroscopy as a fast method to measure the
scattering length of the atoms.Comment: submitted to PRL, 5 pages, 5 figure
Test results of collision warning systems on off-highway dump trucks: phase 2
"This report summarizes ongoing research at the National Institute for Occupational Safety and Health, Spokane Research Laboratory, in which collision warning systems for surface mining dump trucks are being evaluated. Common accidents involve these large trucks running over smaller vehicles or pedestrian workers. Collision warning systems currently use one of several methods, including radar, radio-frequency-signal detection, or ultrasonic signals, to detect and warn of the presence of an object or person in the blind spots of the mining equipment. Most available systems have not been tested on large off-highway dump trucks. This report evaluates several systems on two sizes of trucks, a 50-ton-capacity truck commonly used in quarries and construction and a 240-ton-capacity truck commonly used in open-pit mines. Tests were conducted to determine false alarm rates, alarm effectiveness, and reliable detection zones for a person and a pickup truck. The results indicate that radar and radiofrequency identification systems show promise for this application and that several of the improved systems are ready for extensive field tests. However, challenges still exist in applying these technologies to large trucks." - NIOSH-2"February 2001."Also available via the World Wide Web as an Acrobat .pdf file (6.17 MB, 27 p.).Includes bibliographical references (p. 21)
Polar Dynamics at the Jahn-Teller Transition in Ferroelectric GaV4S8
We present a dielectric spectroscopy study of the polar dynamics linked to
the orbitally driven ferroelectric transition in the skyrmion host GaV4S8. By
combining THz and MHz-GHz spectroscopy techniques, we succeed in detecting the
relaxational dynamics arising from coupled orbital and polar fluctuations in
this material and traced its temperature dependence in the paraelectric as well
as in the ferroelectric phase. The relaxation time significantly increases when
approaching the critical temperature from both sides of the transition. It is
natural to assume that these polar fluctuations map the orbital dynamics at the
Jahn-Teller transition. Due to the first-order character of the
orbital-ordering transition, the relaxation time shows an enormous jump of
about five orders of magnitude at the polar and structural phase transition.Comment: 5 pages, 4 figure
The Impact of Leadership Training on the Development of Selected Nebraska Communities
Securing of appropriate resources is a vital activity for communities if they are to exist and grow in contemporary society. The increase in the size, scope, and complexity of municipal services has sometimes outpaced municipalities\u27 capacities to manage those services. The ability of local leaders to manage a community\u27s resources efficiently and effectively has been one of the central issues underlying community development trends throughout the past decade. New demands on local decision makers require innovative strategies to improve managerial skills among the cities\u27 core leadership
Color infrared photography and thermal infrared imagery of selected locations along the Missouri River between Omaha and Blair, Nebraska
CER71-72MMS-JFR 49.June, 1972.Submitted to Department of the Army Omaha District, Corps of Engineers Omaha, Nebraska.Circulating copy deaccessioned 2020
Continuous-phase properties of the near-injector region of nonevaporating pressure-atomized sprays
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76593/1/AIAA-1990-464-584.pd
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