1,687 research outputs found
Numerical comparison of pipe-column-separation models
Results comparing six column-separation numerical models for simulating localized vapor cavities and distributed vaporous cavitation in pipelines are presented. The discrete vapor-cavity model (DVCM) is shown to be quite sensitive to selected input parameters. For short pipeline systems, the maximum pressure rise following column separation can vary markedly for small changes in wave speed, friction factor, diameter, initial velocity, length of pipe, or pipe slope. Of the six numerical models, three perform consistently over a broad number of reaches. One of them, the discrete gas-cavity model, is recommended for general use as it is least sensitive to input parameters or to the selected discretization of the pipeline. Three models provide inconsistent estimates of the maximum pressure rise as the number of reaches is increased; however, these models do give consistent results provided the ratio of maximum cavity size to reach volume is kept below 10%.Angus R. Simpson and Anton Bergan
P01.31. Yoga therapy associated with increased brain GABA levels and decreased depressive symptoms in subjects with major depressive disorder: a pilot study
Discovering Valuable Items from Massive Data
Suppose there is a large collection of items, each with an associated cost
and an inherent utility that is revealed only once we commit to selecting it.
Given a budget on the cumulative cost of the selected items, how can we pick a
subset of maximal value? This task generalizes several important problems such
as multi-arm bandits, active search and the knapsack problem. We present an
algorithm, GP-Select, which utilizes prior knowledge about similarity be- tween
items, expressed as a kernel function. GP-Select uses Gaussian process
prediction to balance exploration (estimating the unknown value of items) and
exploitation (selecting items of high value). We extend GP-Select to be able to
discover sets that simultaneously have high utility and are diverse. Our
preference for diversity can be specified as an arbitrary monotone submodular
function that quantifies the diminishing returns obtained when selecting
similar items. Furthermore, we exploit the structure of the model updates to
achieve an order of magnitude (up to 40X) speedup in our experiments without
resorting to approximations. We provide strong guarantees on the performance of
GP-Select and apply it to three real-world case studies of industrial
relevance: (1) Refreshing a repository of prices in a Global Distribution
System for the travel industry, (2) Identifying diverse, binding-affine
peptides in a vaccine de- sign task and (3) Maximizing clicks in a web-scale
recommender system by recommending items to users
Influence of soil drought stress on photosynthesis, carbohydrates and the nitrogen and phophorus absorb in different section of leaves and stem of Fugi/M.9EML, a young apple seedling
Drought is the most significant limiting factor for plant cultivation. Greenhouse-grown 1-year-old potted M.9EMLA apple trees (Malus domestica Borkh.) (after growing for 6 weeks) were subjected to drought stress by withholding water for an additional six-week period. The photosynthesis, carbohydrates and the nitrogen (N), phosphorus (P) absorb in the upper, middle and lower leaves of the seedlings were determined. The results revealed that drought stress obviously decreased the photosynthesis and carbohydrates contents in the leaves at all sections of shoot compared with the control. Sorbitol and glucose concentrations increased over time and was kept at a higher level during the drought stress period whereas sucrose concentration declined. N content in the leaves kept a flat trend and was higher than that of the control while P concentration decreased compared with the control. These results demonstrated that drought stress prevented N and P absorbtion and decreased RWC of apple leaves, which caused the decline of photosynthesis and transpiration. Thus, the direct phenotype was the slowed growth which was specifically expressed in decreased plant height, number of leaves, average leaf area and stem diameter.Keywords: Malus domestica Borkh, sorbitol, water deficit, transpirationAfrican Journal of Biotechnology Vol. 9(33), pp. 5320-5325, 16 August, 201
Pilot, Rollout and Monte Carlo Tree Search Methods for Job Shop Scheduling
Greedy heuristics may be attuned by looking ahead for each possible choice,
in an approach called the rollout or Pilot method. These methods may be seen as
meta-heuristics that can enhance (any) heuristic solution, by repetitively
modifying a master solution: similarly to what is done in game tree search,
better choices are identified using lookahead, based on solutions obtained by
repeatedly using a greedy heuristic. This paper first illustrates how the Pilot
method improves upon some simple well known dispatch heuristics for the
job-shop scheduling problem. The Pilot method is then shown to be a special
case of the more recent Monte Carlo Tree Search (MCTS) methods: Unlike the
Pilot method, MCTS methods use random completion of partial solutions to
identify promising branches of the tree. The Pilot method and a simple version
of MCTS, using the -greedy exploration paradigms, are then
compared within the same framework, consisting of 300 scheduling problems of
varying sizes with fixed-budget of rollouts. Results demonstrate that MCTS
reaches better or same results as the Pilot methods in this context.Comment: Learning and Intelligent OptimizatioN (LION'6) 7219 (2012
Breath Practices for Survivor and Caregiver Stress, Depression, and Post- traumatic Stress Disorder: Connection, Co-regulation, Compassion
Does compassion itself benefit the healing process or does the activation of neurophysiological processes, from which the experience of compassion arises, trigger a cascade of physical and psychological changes that support health and well-being? Exploration of the neurological substrates of compassion reveals multiple healing pathways that can be activated by mind-body practices. Furthermore, these pathways affect physical health, emotion regulation, and how we perceive and relate to others.
Physiological states affect the capacity for empathy, compassion and understanding. A state of calm alertness based on sympatho-vagal balance may support such high-level prosocial functions. Evidence suggests that polyvagal-informed mind-body practices, particularly Voluntarily Regulated Breathing Practices (VRBPs), efficiently induce such physiological states and that these same states can reduce inflammation and oxidative stress, while improving cardiovascular function, respiratory efficiency, and physical health.
Mind-body practices, such as Coherent or Resonant Breathing can balance, strengthen, and increase the adaptive flexibility of stress response systems, potentially counteracting the detrimental effects of excess stress, neglect, and trauma on emotion regulation, physical health, and the ability to experience love and compassion. Research is needed to support integration of mind-body practices into healthcare systems. The methods being used to study mind-body techniques may be further refined by considering the target symptoms, population being studied, specific parameters of each practice, and methods of teaching subjects.
The current state of global health calls for treatments that can be delivered to large populations by small numbers of healthcare providers under conditions where resources are limited. Slow gentle Coherent or Resonant Breathing and related mind-body practices are low cost, low risk, easily taught, rapidly effective, scalable, non-stigmatizing, and sustainable. At the convergence of neurophysiological research with contemplative and other mind-body practices, we marvel at the possibilities for relieving emotional and physical suffering as well as improving how we relate to one another
Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator
We show that the properties of the electron beam and bright x-rays produced
by a laser wakefield accelerator can be predicted if the distance over which
the laser self-focuses and compresses prior to self-injection is taken into
account. A model based on oscillations of the beam inside a plasma bubble shows
that performance is optimised when the plasma length is matched to the laser
depletion length. With a 200~TW laser pulse this results in an x-ray beam with
median photon energy of \unit[20]{keV}, photons above
\unit[1]{keV} per shot and a peak brightness of \unit[3 \times
10^{22}]{photons~s^{-1}mrad^{-2}mm^{-2} (0.1\% BW)^{-1}}.Comment: 5 pages, 4 figure
Evaluation of Revalor-XH for beef heifers fed different days on feed
Heifers were treated with either no implant, an initial implant of Revalor-200 and re-implanted with Revalor-200, or Revalor-XH and assigned to one of four serial slaughter harvests at 151, 165, 179, and 193 days on feed to determine the effects on feedlot performance and carcass characteristics. Implanting heifers increased final BW, ADG and HCW while decreasing marbling score and improving feed efficiency compared to non-implanted heifers. Increasing days on feed decreased ADG while increasing feed efficiency, HCW, fat thickness, marbling score, and calculated yield grade. By increasing HCW sold, implanting revenue can be maximized, assuming added risk for YG discounts
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