10,439 research outputs found
Performance of shallow anchor in ice-rich silt
Thesis (M.S.) University of Alaska Fairbanks, 2014Shallow anchor systems have been widely used for decades due to their time and cost efficiency. Yet when it comes to cold regions like Alaska, new challenges caused by the harsh environment need to be resolved before they are used extensively in cold regions. One challenge associated with anchor installation could be the potential thawing of warm permafrost due to the grout mortar hydration, which might undermine the capacity of the anchor. Another challenge is that due to low temperature the grout may cure slower or not cure at all, which will also result in a significant decrease in the ultimate strength of the anchor. Field tests were conducted to evaluate the performance of shallow anchors including duckbill anchors and grouted anchors with three types of different grouting materials, including Microsil Anchor Grout, Bentonite Clay and a newly-developed Antifreeze Grout Mortar. Constant-load creep test and pullout test were conducted to evaluate the performance of the anchors. Test results indicated that the anchors grouted with Antifreeze Grout Mortar caused the least permafrost disturbance and degradation, gained the largest tensile strength, exhibited the least creep displacement, and showed relatively large pullout capacity, and thus achieved the best performance among all types of shallow anchors
A Bio-Wicking System to Mitigate Capillary Water in Base Course
Water within pavement layers is the major cause of pavement deteriorations. High water content results in significant reduction in soil’s resilient behavior and increase in permanent deformation. Conventional drainage systems can only drain gravity water but not capillary water. Both preliminary lab and field tests have proven the drainage efficiency of a newly developed H2Ri geotextile with wicking fabrics. This bio-wicking system aims at resolving the potential issues that the original design may encounter: (1) H2Ri ultraviolet degradation, (2) H2Ri mechanical failure, (3) loss of drainage function under high suction, and (4) clogging and salt concentration.
Both elemental level and full-scale test results indicated that the bio-wicking system is more effective in draining capillary water within the base courses compared with original design, in which the geotextile is directly exposed to the open air. However, a good drainage condition is required for the bio-wicking system to maintain its drainage efficiency. Accumulation of excess water will result in water re-entering the road embankment. Moreover, grass root and geotextile share the same working mechanism in transporting water. In the proposed bio-wicking system, the relatively smaller channels in the grass roots further ensures water moving from H2Ri geotextile, transporting through the stems of grass, and eventually evapo-transpiring into the air at the leaf-air interfaces. In sum, the bio-wicking system seemed to successfully address the concerns in the preliminary design and is a more efficient system to dehydrate the road embankment under unsaturated conditions.TenCate Geosynthetic
Flow-based Influence Graph Visual Summarization
Visually mining a large influence graph is appealing yet challenging. People
are amazed by pictures of newscasting graph on Twitter, engaged by hidden
citation networks in academics, nevertheless often troubled by the unpleasant
readability of the underlying visualization. Existing summarization methods
enhance the graph visualization with blocked views, but have adverse effect on
the latent influence structure. How can we visually summarize a large graph to
maximize influence flows? In particular, how can we illustrate the impact of an
individual node through the summarization? Can we maintain the appealing graph
metaphor while preserving both the overall influence pattern and fine
readability?
To answer these questions, we first formally define the influence graph
summarization problem. Second, we propose an end-to-end framework to solve the
new problem. Our method can not only highlight the flow-based influence
patterns in the visual summarization, but also inherently support rich graph
attributes. Last, we present a theoretic analysis and report our experiment
results. Both evidences demonstrate that our framework can effectively
approximate the proposed influence graph summarization objective while
outperforming previous methods in a typical scenario of visually mining
academic citation networks.Comment: to appear in IEEE International Conference on Data Mining (ICDM),
Shen Zhen, China, December 201
Effects of electrode surface roughness on motional heating of trapped ions
Electric field noise is a major source of motional heating in trapped ion
quantum computation. While the influence of trap electrode geometries on
electric field noise has been studied in patch potential and surface adsorbate
models, only smooth surfaces are accounted for by current theory. The effects
of roughness, a ubiquitous feature of surface electrodes, are poorly
understood. We investigate its impact on electric field noise by deriving a
rough-surface Green's function and evaluating its effects on adsorbate-surface
binding energies. At cryogenic temperatures, heating rate contributions from
adsorbates are predicted to exhibit an exponential sensitivity to local surface
curvature, leading to either a large net enhancement or suppression over smooth
surfaces. For typical experimental parameters, orders-of-magnitude variations
in total heating rates can occur depending on the spatial distribution of
absorbates. Through careful engineering of electrode surface profiles, our
results suggests that heating rates can be tuned over orders of magnitudes.Comment: 12 pages, 5 figure
Non-separated states from squeezed dark-state polaritons in electromagnetically-induced-transparency media
Within the frame of quantized dark-state polaritons in
electromagnetically-induced-transparency media, noise fluctuations in the
quadrature components are studied. Squeezed state transfer, quantum
correlation, and noise entanglement between probe field and atomic polarization
are demonstrated in single- and double- configurations, respectively.
Even though a larger degree of squeezing parameter in the continuous variable
helps to establish stronger quantum correlations, inseparability criterion is
satisfied only within a finite range of squeezing parameter. The results
obtained in the present study may be useful for guiding experimental
realization of quantum memory devices for possible applications in quantum
information and computation.Comment: 12 pages, 7 figure
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