7,347 research outputs found
Issues in Evaluating Health Department Web-Based Data Query Systems: Working Papers
Compiles papers on conceptual and methodological topics to consider in evaluating state health department systems that provide aggregate data online, such as taxonomy, logic models, indicators, and design. Includes surveys and examples of evaluations
Can conduction induce convection? The non-linear saturation of buoyancy instabilities in dilute plasmas
We study the effects of anisotropic thermal conduction on low-collisionality,
astrophysical plasmas using two and three-dimensional magnetohydrodynamic
simulations. For weak magnetic fields, dilute plasmas are buoyantly unstable
for either sign of the temperature gradient: the heat-flux-driven buoyancy
instability (HBI) operates when the temperature increases with radius while the
magnetothermal instability (MTI) operates in the opposite limit. In contrast to
previous results, we show that, in the presence of a sustained temperature
gradient, the MTI drives strong turbulence and operates as an efficient
magnetic dynamo (akin to standard, adiabatic convection). Together, the
turbulent and magnetic energies contribute up to ~10% of the pressure support
in the plasma. In addition, the MTI drives a large convective heat flux, ~1.5%
of rho c_s^3. These findings are robust even in the presence of an external
source of strong turbulence. Our results on the nonlinear saturation of the HBI
are consistent with previous studies but we explain physically why the HBI
saturates quiescently by re-orienting the magnetic field (suppressing the
conductive heat flux through the plasma), while the MTI saturates by generating
sustained turbulence. We also systematically study how an external source of
turbulence affects the saturation of the HBI: such turbulence can disrupt the
HBI only on scales where the shearing rate of the turbulence is faster than the
growth rate of the HBI. In particular, our results provide a simple mapping
between the level of turbulence in a plasma and the effective isotropic thermal
conductivity. We discuss the astrophysical implications of these findings, with
a particular focus on the intracluster medium of galaxy clusters.Comment: 18 pages, 14 figures. Submitted to MNRA
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Cognitive barriers during monitoring-based commissioning of buildings
Monitoring-based commissioning (MBCx) is a continuous building energy management process used to optimize energy performance in buildings. Although monitoring-based commissioning (MBCx) can reduce energy waste by up to 20%, many buildings still underperform due to issues such as unnoticed system faults and inefficient operational procedures. While there are technical barriers that impede the MBCx process, such as data quality, the focuses of this paper are the non-technical, behavioral and organizational, barriers that contribute to issues initiating and implementing MBCx. In particular, this paper discusses cognitive biases, which can lead to suboptimal outcomes in energy efficiency decisions, resulting in missed opportunities for energy savings. This paper provides evidence of cognitive biases in decisions during the MBCx process using qualitative data from over 40 public and private sector organizations. The results describe barriers resulting from cognitive biases, listed in descending order of occurrence, including: risk aversion, social norms, choice overload, status quo bias, information overload, professional bias, and temporal discounting. Building practitioners can use these results to better understand potential cognitive biases, in turn allowing them to establish best practices and make more informed decisions. Researchers can use these results to empirically test specific decision interventions and facilitate more energy efficient decisions
Motion software for a synergistic six-degree-of-freedom motion base
Computer software for the conversion of fixed-base simulations into moving-base simulations utilizing a synergistic six-degree-of-freedom motion simulator has been developed. This software includes an actuator extension transformation, inverse actuator extension transformation, a centroid transformation, and a washout circuit. Particular emphasis is placed upon the washout circuitry as adapted to fit the synergistic motion simulator. The description of the washout circuitry and illustration by means of a sample flight emphasize that translational cue representation may be of good fidelity, but care in the selection of parameters is very necessary, particularly in regard to anomalous rotational cues
Comparison of a linear and a nonlinear washout for motion simulators utilizing objective and subjective data from CTOL transport landing approaches
Objective and subjective data gathered in the processes of comparing a linear and a nonlinear washout for motion simulators reveal that there is no difference in the pilot performance measurements used during instrument landing system (ILS) approaches with a Boeing 737 conventional takeoff and landing (CTOL) airplane between fixed base, linear washout, and nonlinear washout operations. However, the subjective opinions of the pilots reveal an important advance in motion cue presentation. The advance is not in the increased cue available over a linear filter for the same amount of motion base travel but rather in the elimination of false rotational rate cues presented by linear filters
Empirical comparison of a fixed-base and a moving-base simulation of a helicopter engaged in visually conducted slalom runs
Combined visual, motion, and aural cues for a helicopter engaged in visually conducted slalom runs at low altitude were studied. The evaluation of the visual and aural cues was subjective, whereas the motion cues were evaluated both subjectively and objectively. Subjective and objective results coincided in the area of control activity. Generally, less control activity is present under motion conditions than under fixed-base conditions, a fact attributed subjectively to the feeling of realistic limitations of a machine (helicopter) given by the addition of motion cues. The objective data also revealed that the slalom runs were conducted at significantly higher altitudes under motion conditions than under fixed-base conditions
Evaluation of a linear washout for simulator motion cue presentation during landing approach
The comparison of a fixed-base versus a five-degree-of-freedom motion base simulation of a 737 conventional take-off and landing (CTOL) aircraft performing instrument landing system (ILS) landing approaches was used to evaluate a linear motion washout technique. The fact that the pilots felt that the addition of motion increased the pilot workload and this increase was not reflected in the objective data results, indicates that motion cues, as presented, are not a contributing factor to root-mean-square (rms) performance during the landing approach task. Subjective results from standard maneuvering about straight-and-level flight for specific motion cue evaluation revealed that the longitudinal channels (pitch and surge) possibly the yaw channel produce acceptable motions. The roll cue representation, involving both roll and sway channels, was found to be inadequate for large roll inputs, as used for example, in turn entries
Whatâs the Story Here? How Catholic University Leaders are Making Sense of Undocumented Student Access.
This study examines how leaders make sense of an unsettled, contemporary issue facing
higher education. It deepens our understanding of how stories may operate in the process of
sensemaking, which has been described as âthe experience of being thrown into an ongoing,
unknowable, unpredictable streaming of experience in search of answers to the question, âWhat's
the story?ââ (Weick, 2008, para. 1). Sensemaking is a powerful tool for understanding how
people engage volatile issues.
The study addresses two research questions: How are Catholic university leaders making
sense of undocumented student access? and What role do stories play in the sensemaking of
these leaders? Situating the study in Catholic higher education, with its own unique historyâ
serving as a vehicle for assimilation into American society, especially for immigrantsâallows us
to explore the spiritual and religious values that operate differently within this sector than
elsewhere in U.S. higher education. That the issue remains unsettled in policy and practice
highlights the effects of volatility on sensemaking.
To learn more about how leaders respond to the challenge of this situation, I conducted
55 interviews in 12 Catholic universities in regions of the U.S. with relatively high
undocumented populations. I find that identity, social context, extracted cues, and stories play
especially important roles in leader sensemaking. Leaders engaged in âconstructing Catholic
identity,â a process of reflection upon the espoused mission values in their institutions which led
to the decision to admit undocumented students. Because of the volatility of undocumented
access and leadersâ fear of negative consequences resulting from engaging the issue, leaders
employed numerous behaviors to manage their commitment (Salancik, 1977). This resulted in
strategic ambiguity that provided some protection for leaders; it also led to communication
breakdowns in universities and the alienation of important institutional leaders.
Canonical stories played an important role in sensemaking, as leaders referred to
âcommunity narrativesâ and âdominant cultural narrativesâ (Rappaport, 2000), often alluding to
them in shorthand. Because their meaning is shared among group members, canonical stories
were especially useful as leaders reflected on the link between institutional histories and
charisms and the decision to admit undocumented students.PhDHigher EducationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111516/1/djpcsc_1.pd
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