3,100 research outputs found
Shape control of large space structures
A survey has been conducted to determine the types of control strategies which have been proposed for controlling the vibrations in large space structures. From this survey several representative control strategies were singled out for detailed analyses. The application of these strategies to a simplified model of a large space structure has been simulated. These simulations demonstrate the implementation of the control algorithms and provide a basis for a preliminary comparison of their suitability for large space structure control
Compatibility Studies of Various Refractory Materials in Contact with Molten Silicon
The production of low cost, efficient solar cells for terrestrial electric power generation involves the manipulation of molten silicon with a present need for noncontaminating, high temperature refractories to be used as containment vessels, ribbon-production dies, and dip-coated substrates. Studies were conducted on the wetting behavior and chemical/physical interactions between molten silicon and various refractory materials
A study to assess COPD Symptom-based Management and to Optimise treatment Strategy in Japan (COSMOS-J) based on GOLD 2011
Background and objective: The Global initiative for chronic Obstructive Lung Disease(GOLD) Committee has proposed a chronic obstructive pulmonary disease (COPD) assessment framework focused on symptoms and on exacerbation risk. This study will evaluate a symptom and exacerbation risk-based treatment strategy based on GOLD in a real-world setting in Japan. Optimal management of COPD will be determined by assessing symptoms using the COPD Assessment Test (CAT) and by assessing the frequency of exacerbations.
Methods: This study (ClinicalTrials.gov identifier: NCT01762800) is a 24-week, multicenter, randomized, double-blind, double-dummy, parallel-group study. It aims to recruit 400 patients with moderate-to-severe COPD. Patients will be randomized to receive treatment with either
salmeterol/fluticasone propionate (SFC) 50/250μg twice daily or with tiotropium bromide 18μg once daily. Optimal management of patients will be assessed at four-weekly intervals and, if patients remain symptomatic, as measured using the CAT, or experience an exacerbation, they
have the option to step up to treatment with both drugs, ie, SFC twice daily and tiotropium once daily (TRIPLE therapy). The primary endpoint of the study will be the proportion of patients who are able to remain on the randomized therapy.
Results: No data are available. This paper summarizes the methodology of the study in advance of the study starting.
Conclusion: The results of this study will help physicians to understand whether TRIPLE therapy is more effective than either treatment strategy alone in controlling symptoms and exacerbations in patients with moderate-to-severe COPD. It will also help physicians to understand the GOLD recommendation work in Japan
Excitable Patterns in Active Nematics
We analyze a model of mutually-propelled filaments suspended in a
two-dimensional solvent. The system undergoes a mean-field isotropic-nematic
transition for large enough filament concentrations and the nematic order
parameter is allowed to vary in space and time. We show that the interplay
between non-uniform nematic order, activity and flow results in spatially
modulated relaxation oscillations, similar to those seen in excitable media. In
this regime the dynamics consists of nearly stationary periods separated by
"bursts" of activity in which the system is elastically distorted and solvent
is pumped throughout. At even higher activity the dynamics becomes chaotic.Comment: 4 pages, 4 figure
Hybrid Method for Digits Recognition using Fixed-Frame Scores and Derived Pitch
This paper presents a procedure of frame normalization based on the traditional dynamic time warping (DTW) using the LPC coefficients. The redefined method is called as the DTW frame-fixing method (DTW-FF), it works by normalizing the word frames of the input against the
reference frames. The enthusiasm to this study is due to neural network limitation that entails a fix number of input nodes for when processing multiple inputs in parallel. Due to this problem, this research is initiated to reduce the amount of computation and complexity in a neural network by reducing the number of inputs into the network. In this study, dynamic warping process is used, in which local distance scores of the warping path are fixed and collected so that their scores are of equal number of frames. Also studied in this paper is the
consideration of pitch as a contributing feature to the speech recognition. Results showed a good performance and
improvement when using pitch along with DTW-FF feature.
The convergence rate between using the steepest gradient
descent is also compared to another method namely conjugate
gradient method. Convergence rate is also improved when
conjugate gradient method is introduced in the back-propagation algorithm
Reduction and reconstruction of stochastic differential equations via symmetries
An algorithmic method to exploit a general class of infinitesimal symmetries
for reducing stochastic differential equations is presented and a natural
definition of reconstruction, inspired by the classical reconstruction by
quadratures, is proposed. As a side result the well-known solution formula for
linear one-dimensional stochastic differential equations is obtained within
this symmetry approach. The complete procedure is applied to several examples
with both theoretical and applied relevance
Spatially Resolved Mapping of Local Polarization Dynamics in an Ergodic Phase of Ferroelectric Relaxor
Spatial variability of polarization relaxation kinetics in relaxor
ferroelectric 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 is studied using time-resolved
Piezoresponse Force Microscopy. Local relaxation attributed to the
reorientation of polar nanoregions is shown to follow stretched exponential
dependence, exp(-(t/tau)^beta), with beta~~0.4, much larger than the
macroscopic value determined from dielectric spectra (beta~~0.09). The spatial
inhomogeneity of relaxation time distributions with the presence of 100-200 nm
"fast" and "slow" regions is observed. The results are analyzed to map the
Vogel-Fulcher temperatures on the nanoscale.Comment: 23 pages, 4 figures, supplementary materials attached; to be
submitted to Phys. Rev. Let
Artificial Neural Network-based error compensation procedure for low-cost encoders
An Artificial Neural Network-based error compensation method is proposed for
improving the accuracy of resolver-based 16-bit encoders by compensating for
their respective systematic error profiles. The error compensation procedure,
for a particular encoder, involves obtaining its error profile by calibrating
it on a precision rotary table, training the neural network by using a part of
this data and then determining the corrected encoder angle by subtracting the
ANN-predicted error from the measured value of the encoder angle. Since it is
not guaranteed that all the resolvers will have exactly similar error profiles
because of the inherent differences in their construction on a micro scale, the
ANN has been trained on one error profile at a time and the corresponding
weight file is then used only for compensating the systematic error of this
particular encoder. The systematic nature of the error profile for each of the
encoders has also been validated by repeated calibration of the encoders over a
period of time and it was found that the error profiles of a particular encoder
recorded at different epochs show near reproducible behavior. The ANN-based
error compensation procedure has been implemented for 4 encoders by training
the ANN with their respective error profiles and the results indicate that the
accuracy of encoders can be improved by nearly an order of magnitude from
quoted values of ~6 arc-min to ~0.65 arc-min when their corresponding
ANN-generated weight files are used for determining the corrected encoder
angle.Comment: 16 pages, 4 figures. Accepted for Publication in Measurement Science
and Technology (MST
Peak Forecasting for Battery-based Energy Optimizations in Campus Microgrids
Battery-based energy storage has emerged as an enabling technology for a
variety of grid energy optimizations, such as peak shaving and cost arbitrage.
A key component of battery-driven peak shaving optimizations is peak
forecasting, which predicts the hours of the day that see the greatest demand.
While there has been significant prior work on load forecasting, we argue that
the problem of predicting periods where the demand peaks for individual
consumers or micro-grids is more challenging than forecasting load at a grid
scale. We propose a new model for peak forecasting, based on deep learning,
that predicts the k hours of each day with the highest and lowest demand. We
evaluate our approach using a two year trace from a real micro-grid of 156
buildings and show that it outperforms the state of the art load forecasting
techniques adapted for peak predictions by 11-32%. When used for battery-based
peak shaving, our model yields annual savings of $496,320 for a 4 MWhr battery
for this micro-grid.Comment: 5 pages. 4 figures, This paper will appear in the Proceedings of ACM
International Conference on Future Energy Systems (e-Energy'20), June 202
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