6,462 research outputs found
Sub-picosecond compression by velocity bunching in a photo-injector
We present an experimental evidence of a bunch compression scheme that uses a
traveling wave accelerating structure as a compressor. The bunch length issued
from a laser-driven radio-frequency electron source was compressed by a factor
>3 using an S-band traveling wave structure located immediately downstream from
the electron source. Experimental data are found to be in good agreement with
particle tracking simulations.Comment: 19 pages, 9 figures, submitted to Phys. Rev. Spec. Topics A&
Mathematical model for the simulation of Dynamic Docking Test System (DDST) active table motion
The mathematical model developed to describe the three-dimensional motion of the dynamic docking test system active table is described. The active table is modeled as a rigid body supported by six flexible hydraulic actuators which produce the commanded table motions
Neural NILM: Deep Neural Networks Applied to Energy Disaggregation
Energy disaggregation estimates appliance-by-appliance electricity
consumption from a single meter that measures the whole home's electricity
demand. Recently, deep neural networks have driven remarkable improvements in
classification performance in neighbouring machine learning fields such as
image classification and automatic speech recognition. In this paper, we adapt
three deep neural network architectures to energy disaggregation: 1) a form of
recurrent neural network called `long short-term memory' (LSTM); 2) denoising
autoencoders; and 3) a network which regresses the start time, end time and
average power demand of each appliance activation. We use seven metrics to test
the performance of these algorithms on real aggregate power data from five
appliances. Tests are performed against a house not seen during training and
against houses seen during training. We find that all three neural nets achieve
better F1 scores (averaged over all five appliances) than either combinatorial
optimisation or factorial hidden Markov models and that our neural net
algorithms generalise well to an unseen house.Comment: To appear in ACM BuildSys'15, November 4--5, 2015, Seou
Polar methane accumulation and rainstorms on Titan from simulations of the methane cycle
Titan has a methane cycle akin to Earth's water cycle. It has lakes in polar regions, preferentially in the north; dry low latitudes with fluvial features and occasional rainstorms; and tropospheric clouds mainly (so far) in southern middle latitudes and polar regions. Previous models have explained the low-latitude dryness as a result of atmospheric methane transport into middle and high latitudes. Hitherto, no model has explained why lakes are found only in polar regions and preferentially in the north; how low-latitude rainstorms arise; or why clouds cluster in southern middle and high latitudes. Here we report simulations with a three-dimensional atmospheric model coupled to a dynamic surface reservoir of methane. We find that methane is cold-trapped and accumulates in polar regions, preferentially in the north because the northern summer, at aphelion, is longer and has greater net precipitation than the southern summer. The net precipitation in polar regions is balanced in the annual mean by slow along-surface methane transport towards mid-latitudes, and subsequent evaporation. In low latitudes, rare but intense storms occur around the equinoxes, producing enough precipitation to carve surface features. Tropospheric clouds form primarily in middle and high latitudes of the summer hemisphere, which until recently has been the southern hemisphere. We predict that in the northern polar region, prominent clouds will form within about two (Earth) years and lake levels will rise over the next fifteen years
Cleaning graphene : a first quantum/classical molecular dynamics approach
Graphene outstanding properties created a huge interest in the condensed
matter community and unprecedented fundings at the international scale in the
hope of application developments. Recently, there have been several reports of
incomplete removal of the polymer resists used to transfer as-grown graphene
from one substrate to another, resulting in altered graphene transport
properties. Finding a large-scale solution to clean graphene from adsorbed
residues is highly desirable and one promising possibility would be to use
hydrogen plasmas. In this spirit, we couple here quantum and classical
molecular dynamics simulations to explore the kinetic energy ranges required by
atomic hydrogen to selectively etch a simple residue, a CH3 group, without
irreversibly damaging the graphene. For incident energies in the 2-15 eV range,
the CH3 radical can be etched by forming a volatile CH4 compound which leaves
the surface, either in the CH4 form or breaking into CH3+H fragments, without
further defect formation. At this energy, adsorption of H atoms on graphene is
possible and further annealing will be required to recover pristine graphene.Comment: 9 figures, 27 page
Mindfulness-Oriented Recovery Enhancement versus CBT for co-occurring substance dependence, traumatic stress, and psychiatric disorders: Proximal outcomes from a pragmatic randomized trial
In clinical settings, there is a high comorbidity between substance use disorders, psychiatric disorders, and traumatic stress. As such, transdiagnostic therapies are needed to address these co-occurring issues efficiently. The aim of the present study was to conduct a pragmatic randomized controlled trial comparing Mindfulness-Oriented Recovery Enhancement (MORE) to group Cognitive-Behavioral Therapy (CBT) and treatment-as-usual (TAU) for previously homeless men residing in a therapeutic community. Men with co-occurring substance use and psychiatric disorders, as well as extensive trauma histories, were randomly assigned to 10 weeks of group treatment with MORE (n=64), CBT (n=64), or TAU (n=52). Study findings indicated that from pre- to post-treatment MORE was associated with modest yet significantly greater improvements in substance craving, post-traumatic stress, and negative affect than CBT, and significantly greater improvements in post-traumatic stress and positive affect than TAU. A significant indirect effect of MORE on decreasing craving and post-traumatic stress by increasing dispositional mindfulness was observed, suggesting that MORE may target these issues via enhancing mindful awareness in everyday life. This pragmatic trial represents the first head-to-head comparison of MORE against an empirically-supported treatment for co-occurring disorders. Results suggest that MORE, as an integrative therapy designed to bolster self-regulatory capacity, may hold promise as a treatment for intersecting clinical conditions
Effect of periodic parametric excitation on an ensemble of force-coupled self-oscillators
We report the synchronization behavior in a one-dimensional chain of
identical limit cycle oscillators coupled to a mass-spring load via a force
relation. We consider the effect of periodic parametric modulation on the final
synchronization states of the system. Two types of external parametric
excitations are investigated numerically: periodic modulation of the stiffness
of the inertial oscillator and periodic excitation of the frequency of the
self-oscillatory element. We show that the synchronization scenarios are ruled
not only by the choice of parameters of the excitation force but depend on the
initial collective state in the ensemble. We give detailed analysis of
entrainment behavior for initially homogeneous and inhomogeneous states. Among
other results, we describe a regime of partial synchronization. This regime is
characterized by the frequency of collective oscillation being entrained to the
stimulation frequency but different from the average individual oscillators
frequency.Comment: Comments and suggestions are welcom
The Australian Orthopaedic Association National Joint Replacement Registry
The document attached has been archived with permission from the editor of the Medical Journal of Australia. An external link to the publisher’s copy is included.In the financial year ending June 2002, 26 689 hip replacements and 26089 knee replacements (total, 52778) were performed in Australia. Hip and knee replacement procedures have increased between 5%-10% each year for the past 10 years, with a combined increase in hip and knee replacement of 13.4% in the past year. The revision rate for hip replacement surgery in Australia is unknown but is estimated to be 20%-24%; the revision rate for hip replacement surgery in Sweden is 7%. Although data collection for the Registry is voluntary, it has 100% compliance from hospitals undertaking joint-replacement surgery.Stephen E Graves, David Davidson, Lisa Ingerson, Philip Ryan, Elizabeth C Griffith, Brian F J McDermott, Heather J McElroy and Nicole L Prat
Research in Brief - Higher Education in an Era of Mass Incarceration: Possibility Under Constraint
In this essay, we explore the purposes of higher education in prison during an era of mass incarceration and contend that the potential of postsecondary educational opportunity in carceral spaces is undermined by a single-minded focus on reducing recidivism. Among the over 2.2 million individuals behind bars in the United States, only 6 percent have access to formal postsecondary educational opportunities, and as a result, most incarcerated students are not on an educational pathway likely to result in academic degree attainment. We must move beyond a recidivist paradigm not because certificate-based and vocational training is not valuable, but because it is simply not enough of what college-in-prison programming can be or do. Drawing upon the experiences of higher education students who are incarcerated, our analysis reveals how even well-intended practices in prison spaces pose obstacles to seeing incarcerated individuals as potential postsecondary students and degree completers
Diffusion-Limited Reactions In Spherical Cavities
We study a quenching reaction occurring at sinks within a spherical cavity and at the cavity surface. One may think of reactions at these two, distinct locations as two, coupled reactive channels. Reactions of the type D* + A--\u3eD + A are studied in the limit of nondilute A, present at both locations, and dilute D, present within the cavity. We use a Monte Carlo algorithm to compute mean rates, pseudo-first-order rates and branching ratios, and compare with results obtained by assuming that the two reactive channels operate in parallel. The ratio of activities of the two channels are varied; static and moving sinks are studied. We discuss an application to the determination of pore structure by NMR (nuclear magnetic resonance)
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