6,194 research outputs found
Exploiting Structural Complexity for Robust and Rapid Hyperspectral Imaging
This paper presents several strategies for spectral de-noising of
hyperspectral images and hypercube reconstruction from a limited number of
tomographic measurements. In particular we show that the non-noisy spectral
data, when stacked across the spectral dimension, exhibits low-rank. On the
other hand, under the same representation, the spectral noise exhibits a banded
structure. Motivated by this we show that the de-noised spectral data and the
unknown spectral noise and the respective bands can be simultaneously estimated
through the use of a low-rank and simultaneous sparse minimization operation
without prior knowledge of the noisy bands. This result is novel for for
hyperspectral imaging applications. In addition, we show that imaging for the
Computed Tomography Imaging Systems (CTIS) can be improved under limited angle
tomography by using low-rank penalization. For both of these cases we exploit
the recent results in the theory of low-rank matrix completion using nuclear
norm minimization
Improved prediction of laminar leading edge separation
Research was conducted to provide a definite criterion for the prediction of the bubble burst on airfoils typical of those used for fighter wings. The approach taken was to correlate existing airfoil bubble burst data using various parameters at the laminar separation point. The method due to Weber was modified to provide a continuous analytic solution for the velocity distribution around the airfoil leading edge. Coupling the modified Weber method with the Stratford laminar separation prediction method leads to a universal chart giving the conditions at separation as a function of stagnation location and leading edge radius. Application of the combined method to available two-dimensional airfoil data resulted in an empirical criterion presenting the limiting local velocity gradient at separation as a function of the boundary layer momentum thickness at separation for bubble burst. The correlation leads as well to the qualitative explanation of two types of laminar stall: thin airfoil and leading edge. The validity of the correlation is demonstrated by predicting the lift coefficient and angle of attack for stall on airfoils with leading edge or trailing edge flaps
Relative Entailment Among Probabilistic Implications
We study a natural variant of the implicational fragment of propositional
logic. Its formulas are pairs of conjunctions of positive literals, related
together by an implicational-like connective; the semantics of this sort of
implication is defined in terms of a threshold on a conditional probability of
the consequent, given the antecedent: we are dealing with what the data
analysis community calls confidence of partial implications or association
rules. Existing studies of redundancy among these partial implications have
characterized so far only entailment from one premise and entailment from two
premises, both in the stand-alone case and in the case of presence of
additional classical implications (this is what we call "relative entailment").
By exploiting a previously noted alternative view of the entailment in terms of
linear programming duality, we characterize exactly the cases of entailment
from arbitrary numbers of premises, again both in the stand-alone case and in
the case of presence of additional classical implications. As a result, we
obtain decision algorithms of better complexity; additionally, for each
potential case of entailment, we identify a critical confidence threshold and
show that it is, actually, intrinsic to each set of premises and antecedent of
the conclusion
Common learning
Consider two agents who learn the value of an unknown parameter by observing a sequence of private signals. The signals are independent and identically distributed across time but not necessarily across agents. We show that when each agent's signal space is finite, the agents will commonly learn the value of the parameter, that is, that the true value of the parameter will become approximate common knowledge. The essential step in this argument is to express the expectation of one agent's signals, conditional on those of the other agent, in terms of a Markov chain. This allows us to invoke a contraction mapping principle ensuring that if one agent's signals are close to those expected under a particular value of the parameter, then that agent expects the other agent's signals to be even closer to those expected under the parameter value. In contrast, if the agents' observations come from a countably infinite signal space, then this contraction mapping property fails. We show by example that common learning can fail in this case
How Has McDonnell Affected Prosecutorsâ Ability to Police Public Corruption? What Are Politicians And Lobbyists Allowed To Do, And What Are Prosecutors Able To Prosecute?
The question posed to the panelists on the first panel is: How has McDonnell affected prosecutorsâ ability to police public corruption? What can politicians and lobbyists do and what can prosecutors prosecute
2015 GSA International Distinguished Lecturer Tours Key Locations in Central and South America
As the International Lecturer from North America, I visited 11 destinations in Ecuador, Peru, Chile, Costa Rica, Mexico, and Puerto Rico. The tour was designed to include locations where the topic of my presentation, âFollowing in the Footsteps of Darwin: Combining Geological and Historical Evidence to Assess Earthquakes and Tsunami Hazards,â would have direct relevance
Teaching strategies to improve student perceptions of academic success: an approach toward immediacy
Teachers are integral portions of a student\u27s ability to succeed in life. However, too often, many teachers do not take the time to develop the necessary skills to become great teachers in order to truly help their students to succeed in life after college. Therefore, I designed an instrument to measure the correlation between instructor immediacy values and students\u27 perceptions of their success in communication classrooms in hopes to demonstrate that teaching behaviors and student success do in fact influence one another. The research question of this thesis was: Is there a relationship between instructor immediacy and student success as perceved by students in communication classrooms? The working hypothesis involved the idea that instructor immediacy values and student success as perceived by students are directly correlated. Moreover, the hypothesis expanded to encompass the idea that studtents\u27 definitions of an excellent teacher will be positively correlated with instructor immediacy behaviors. To address the research queslion and hypotheses, I designed a questionnaire and surveyed 204 students in communication classes. I performed a correlation assessment of the quantitative data in SPSS and analyzed the open-ended questions via content analysis in order to report the data in a mixed methods approach. Findings from this triangulated approach suggest that instructor immediacy and student success as perceived by students are not significantly correlated, but trends and patterns suggest a correlation and implications for future research regarding this topic --Document
Costs of Inaction on Maternal Mortality: Qualitative Evidence of the Impacts of Maternal Deaths on Living Children in Tanzania.
Little is known about the interconnectedness of maternal deaths and impacts on children, beyond infants, or the mechanisms through which this interconnectedness is established. A study was conducted in rural Tanzania to provide qualitative insight regarding how maternal mortality affects index as well as other living children and to identify shared structural and social factors that foster high levels of maternal mortality and child vulnerabilities. Adult family members of women who died due to maternal causes (Nâ=â45) and key stakeholders (Nâ=â35) participated in in-depth interviews. Twelve focus group discussions were also conducted (Nâ=â83) among community leaders in three rural regions of Tanzania. Findings highlight the widespread impact of a woman's death on her children's health, education, and economic status, and, by inference, the roles that women play within their families in rural Tanzanian communities. The full costs of failing to address preventable maternal mortality include intergenerational impacts on the nutritional status, health, and education of children, as well as the economic capacity of families. When setting priorities in a resource-poor, high maternal mortality country, such as Tanzania, the far-reaching effects that reducing maternal deaths can have on families and communities, as well as women's own lives, should be considered
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