13,777 research outputs found
Float-polishing process and analysis of float-polished quartz
A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms
Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp
Observations were made of the open clusters M35 and NGC 2158 during the
initial K2 campaign (C0). Reducing these data to high-precision photometric
time-series is challenging due to the wide point spread function (PSF) and the
blending of stellar light in such dense regions. We developed an
image-subtraction-based K2 reduction pipeline that is applicable to both
crowded and sparse stellar fields. We applied our pipeline to the data-rich C0
K2 super-stamp, containing the two open clusters, as well as to the neighboring
postage stamps. In this paper, we present our image subtraction reduction
pipeline and demonstrate that this technique achieves ultra-high photometric
precision for sources in the C0 super-stamp. We extract the raw light curves of
3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for
systematic effects. We compare our photometric results with the prior
reductions published in the literature. For detrended, TFA-corrected sources in
the 12--12.25 magnitude range, we achieve a best 6.5 hour window
running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 magnitude range. For stars with , our detrended and
6.5 hour binned light curves achieve the highest photometric precision.
Moreover, all our TFA-corrected sources have higher precision on all time
scales investigated. This work represents the first published image subtraction
analysis of a K2 super-stamp. This method will be particularly useful for
analyzing the Galactic bulge observations carried out during K2 campaign 9. The
raw light curves and the final results of our detrending processes are publicly
available at \url{http://k2.hatsurveys.org/archive/}.Comment: Accepted for publication in PASP. 14 pages, 5 figures, 2 tables.
Light curves available from http://k2.hatsurveys.org/archive
Anredera cordifolia a new host of Dichotomophthora sp.
Resumo: Anredera cordifolia (Basellaceae) is a highly invasive species native from South America, including Brazil. In January 2016, several plants of A. cordifolia showing a foliar spot were observed in Jaguariúna/SP. The symptoms were initially characterized by small circular brown dots, with reddish margins, sometimes becoming confluent, later evolving to large blighted areas, sometimes with concentric rings and profuse fungal sporulation, resulting in early foliar abscission. Samples were collected and examined under a stereomicroscope and a dematiaceous hyphomycete was consistently found associated to the symptoms. Glass slides containing fungal structures obtained from in vivo samples and also from cultures were examined under a microscope and the fungus was identified as belonging to the genus Dichotomophthora. Pathogenicity tests proved that the fungus was able to cause similar symptoms on the original host (A. cordifolia) and also on Portulaca oleraceae and P. grandiflora. Although the genus Dichotomophthora have been previously reported on Basella rubra (Basellaceae) in China, to our knowledge, this is the first report of this genus on Anredera worldwide
Sistema de produção de leite em Rondônia: produção, reprodução, nutrição e alimentação.
Esta publicação apresenta um estudo sobre a produção leiteira no Estado de RO e propõe ações otimizadoras da produção.bitstream/item/24795/1/rt91-sistemadeproducaodeleite.pd
Non-factorizable long distance contributions in color suppressed decays of B mesons
, , and decays are
studied. Their amplitude is given by a sum of factorized and non-factorizable
ones. The latter which is estimated by using a hard pion approximation is
rather small in color favored and decays but still
can efficiently interfere with the main amplitude given by the factorization.
In the color suppressed and decays, the
non-factorizable contribution is very important. The sum of the factorized and
non-factorizable amplitudes can reproduce well the existing experimental data
on the branching ratios for the color favored and
and the color suppressed and decays by
taking reasonable values of unknown parameters involved.Comment: 19 pages, Revte
Sharp photoluminescence of Pr3+ ions in yttrium oxyfluoride nanospheres: thermographic phosphor characteristics using the fluorescence intensity ratio technique
YOF:Pr nanoparticles prepared by Pechni sol-gel method were investigated for temperature sensing in this work. Structural investigation such as XRD, Raman, SEM and EDS were done. Photoluminescence experiments at ambient temperature for three different concentrations and with variation in temperature were performed for application in fluorescence intensity ratio (FIR) technique. The FIR of the thermally coupled levels (TCL) 3P0 and 3P1 was determined with respect to temperature and found that the relative sensitivity of the material is 9.37 and 0.87% K−1 at 90 and 300 K, respectively. Results proved that Pr3+ in YOF nanoparticles can be used for non-contact temperature determination.publishe
SmarPer: Context-Aware and Automatic Runtime-Permissions for Mobile Devices
Permission systems are the main defense that mobile platforms, such as Android and iOS, offer to users to protect their private data from prying apps. However, due to the tension between usability and control, such systems have several limitations that often force users to overshare sensitive data. In this work, we address some of these limitations with SmarPer, an advanced permission mechanism for Android. First, to address the rigidity of current permission systems and their poor matching of users' privacy preferences, SmarPer relies on contextual information and machine learning to predict permission decisions at runtime. Using our SmarPer implementation, we collected 8,521 runtime permission decisions from 41 participants in real conditions. Note that the goal of SmarPer is to mimic the users decisions, not to make privacy-preserving decisions per se. With this unique data set, we show that tting an efcient Bayesian linear regression model results in a mean correct classication rate of 80% (3%). This represents a mean relative improvement of 50% over a user-dened static permission policy, i.e., the model used in current permission systems. Second, SmarPer also focuses on the suboptimal trade-off between privacy and utility; instead of only “allow” or “deny” decisions, SmarPer also offers an “obfuscate” option where users can still obtain utility by revealing partial information to apps. We implemented obfuscation techniques in SmarPer for different data types and evaluated them during our data collection campaign. Our results show that 73% of the participants found obfuscation useful and it accounted for almost a third of the total number of decisions. In short, we are the first to show, using a large dataset of real in situ permission decisions, that it is possible to learn users’ unique decision patterns at runtime using contextual information while supporting data obfuscation; this an important step towards automating the management of permissions in smartphones
User behaviour analysis and personalized TV content recommendation
Nowadays, there are many channels and television (TV) programs available, and when the viewer is confronted with this amount of information has difficulty in deciding which wants to see. However, there are moments of the day that viewers see always the same channels or programs, that is, viewers have TV content consumption habits. The aim of this paper was to develop a recommendation system that to be able to recommend TV content considering the viewer profile, time and weekday.
For the development of this paper, were used Design Science Research (DSR) and Cross Industry Standard Process for Data Mining (CRISP-DM) methodologies. For the development of the recommendation model, two approaches were considered: a deterministic approach and a Machine Learning (ML) approach. In the ML approach, K-means algorithm was used to be possible to combine STBs with similar profiles. In the deterministic approach the behaviors of the viewers are adjusted to a profile that will allow you to identify the content you prefer. Here, recommendation system analyses viewer preferences by hour and weekday, allowing customization of the system, considering your historic, recommending what he wants to see at certain time and weekday.
ML approach was not used due to amount of data extracted and computational resources available. However, through deterministic methods it was possible to develop a TV content recommendation model considering the viewer profile, the weekday and the hour. Thus, with the results it was possible to understand which viewer profiles where the ML can be used.COMPETE: POCI-01-0145-FEDER-007043 and FCT (Fundação para a Ciência e Tecnologia) within the Project Scope: UID/CEC/00319/2013 and was developed in partnership with AlticeLab
DECam integration tests on telescope simulator
The Dark Energy Survey (DES) is a next generation optical survey aimed at
measuring the expansion history of the universe using four probes: weak
gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and
Type Ia supernovae. To perform the survey, the DES Collaboration is building
the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera
which will be mounted at the Blanco 4-meter telescope at the Cerro Tololo
Inter- American Observatory. DES will survey 5000 square degrees of the
southern galactic cap in 5 filters (g, r, i, z, Y). DECam will be comprised of
74 250 micron thick fully depleted CCDs: 62 2k x 4k CCDs for imaging and 12 2k
x 2k CCDs for guiding and focus. Construction of DECam is nearing completion.
In order to verify that the camera meets technical specifications for DES and
to reduce the time required to commission the instrument, we have constructed a
full sized telescope simulator and performed full system testing and
integration prior to shipping. To complete this comprehensive test phase we
have simulated a DES observing run in which we have collected 4 nights worth of
data. We report on the results of these unique tests performed for the DECam
and its impact on the experiments progress.Comment: Proceedings of the 2nd International Conference on Technology and
Instrumentation in Particle Physics (TIPP 2011). To appear in Physics
Procedia. 8 pages, 3 figure
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