974 research outputs found
Kajian Sebaran Ukuran Butir Sedimen Di Perairan Gresik, Jawa Timur
Tiap tahun pengangkutan sedimen menuju laut dapat mencapai jutaan meter kubik. Hal tersebut dapat mengakibatkan Perubahan muka bumi dan dapat mengganggu aktivitas dari biota perairan. Sedimen yang telah masuk dalam lingkungan perairan akan mengendap dan terdistribusi oleh proses oseanografi. Lokasi Perairan Gresik yang berada pada muara sungai memiliki kesesuaian dengan kajian penelitian. Tujuan dari penelitian ini adalah untuk mengetahui jenis sedimen di Perairan Gresik dan pendistribusiannya. Penelitian ini menggunakan metode purposive sampling. Hasil dari penelitian ini menunjukkan bahwa terdapat dua fraksi sedimen di Perairan Gresik, yaitu sedimen pasir dan pasir berlanau, dimana pola distribusinya menunjukan daerah pesisir didominasi oleh sedimen pasir dan di laut lepas yang berjenis pasir berlanau
Design and construction of an optical test bed for LISA imaging systems and tilt-to-length coupling
The laser interferometer space antenna (LISA) is a future space-based interferometric gravitational-wave detector consisting of three spacecraft in a triangular configuration. The interferometric measurements of path length changes between satellites will be performed on optical benches in the satellites. Angular misalignments of the interfering beams couple into the length measurement and represent a significant noise source. Imaging systems will be used to reduce this tilt-to-length coupling.
We designed and constructed an optical test bed to experimentally investigate tilt-to-length coupling. It consists of two separate structures, a minimal optical bench and a telescope simulator. The minimal optical bench comprises the science interferometer where the local laser is interfered with light from a remote spacecraft. In our experiment, a simulated version of this received beam is generated on the telescope simulator. The telescope simulator provides a tilting beam, a reference interferometer and an additional static beam as a phase reference. The tilting beam can either be a flat-top beam or a Gaussian beam. We avoid tilt-to-length coupling in the reference interferometer by using a small photo diode placed at an image of the beam rotation point. We show that the test bed is operational with an initial measurement of tilt-to-length coupling without imaging systems.
Furthermore, we show the design of two different imaging systems whose performance will be investigated in future experiments
PEXO : a global modeling framework for nanosecond timing, microsecond astrometry, and ÎĽm/s radial velocities
54 pages, 2 tables, 19 figures, accepted for publication in ApJS, PEXO is available at https://github.com/phillippro/pexoThe ability to make independent detections of the signatures of exoplanets with complementary telescopes and instruments brings a new potential for robust identification of exoplanets and precision characterization. We introduce PEXO, a package for Precise EXOplanetology to facilitate the efficient modeling of timing, astrometry, and radial velocity data, which will benefit not only exoplanet science but also various astrophysical studies in general. PEXO is general enough to account for binary motion and stellar reflex motions induced by planetary companions and is precise enough to treat various relativistic effects both in the solar system and in the target system. We also model the post-Newtonian barycentric motion for future tests of general relativity in extrasolar systems. We benchmark PEXO with the pulsar timing package TEMPO2 and find that PEXO produces numerically similar results with timing precision of about 1 ns, space-based astrometry to a precision of 1{\mu}as, and radial velocity of 1 {\mu}m/s and improves on TEMPO2 for decade-long timing data of nearby targets, due to its consideration of third-order terms of Roemer delay. PEXO is able to avoid the bias introduced by decoupling the target system and the solar system and to account for the atmospheric effects which set a practical limit for ground-based radial velocities close to 1 cm/s. Considering the various caveats in barycentric correction and ancillary data required to realize cm/s modeling, we recommend the preservation of original observational data. The PEXO modeling package is available at GitHub (https://github.com/phillippro/pexo).Peer reviewe
Preparation and Evaluation of Rice Bran-Modified Urea Formaldehyde as Environmental Friendly Wood Adhesive
In this study, defatted rice bran (RB) is used to prepare an environmentally friendly adhesive through chemical modifications. The RB is mixed with distilled water with ratios of 1:5 and 1:4 to prepare Type A and Type B adhesives, respectively having pH of 6, 8 and 10. Type A adhesive is prepared by treating RB with 1% potassium permanganate and 4% poly(vinyl alcohol), whereas Type B is formulated by adding 17.3% formaldehyde and 5.7% urea to RB. Viscosity, gel time, solid content, shear strength, Fourier transform infrared (FTIR) spectroscopy is carried out, and glass transition temperature (T-g), and activation energy (E-a) are determined to evaluate the performance of the adhesives. E-a data reveal that adhesives prepared at mild alkaline (pH 8) form long-chain polymers. Gel time is higher in the fabricated adhesives than that of the commercial urea formaldehyde (UF). FTIR data suggest that functional groups of the raw RB are chemically modified, which enhances the bondability of the adhesives. Shear strength data indicates that bonding strength increases with increasing pH. Similar results are also observed for physical and mechanical properties of fabricated particleboards with the adhesives. The results demonstrate that RB-based adhesives can be used as a potential alternative to currently used UF-based resin
Gravitational Waves from Gravitational Collapse
Gravitational wave emission from the gravitational collapse of massive stars
has been studied for more than three decades. Current state of the art
numerical investigations of collapse include those that use progenitors with
realistic angular momentum profiles, properly treat microphysics issues,
account for general relativity, and examine non--axisymmetric effects in three
dimensions. Such simulations predict that gravitational waves from various
phenomena associated with gravitational collapse could be detectable with
advanced ground--based and future space--based interferometric observatories.Comment: 68 pages including 13 figures; revised version accepted for
publication in Living Reviews in Relativity (http://www.livingreviews.org
Young and Intermediate-age Distance Indicators
Distance measurements beyond geometrical and semi-geometrical methods, rely
mainly on standard candles. As the name suggests, these objects have known
luminosities by virtue of their intrinsic proprieties and play a major role in
our understanding of modern cosmology. The main caveats associated with
standard candles are their absolute calibration, contamination of the sample
from other sources and systematic uncertainties. The absolute calibration
mainly depends on their chemical composition and age. To understand the impact
of these effects on the distance scale, it is essential to develop methods
based on different sample of standard candles. Here we review the fundamental
properties of young and intermediate-age distance indicators such as Cepheids,
Mira variables and Red Clump stars and the recent developments in their
application as distance indicators.Comment: Review article, 63 pages (28 figures), Accepted for publication in
Space Science Reviews (Chapter 3 of a special collection resulting from the
May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space
Age
Life cycle assessment of bacterial cellulose production
Purpose
Bacterial cellulose (BC), obtained by fermentation, is an innovative and promising material with a broad spectrum of potential applications. Despite the increasing efforts towards its industrialization, a deeper understanding of the environmental impact related to the BC production process is still required. This work aimed at quantifying the environmental, health, and resource depletion impacts related to a production of BC.
Methods
An attributional life cycle assessment (LCA) was applied to a process design of production of BC, by static culture, following a cradle-to-gate approach. The LCA was modeled with GaBi Pro Software using the ReCiPe 2016 (H) methodology with environmental impact indicators at midpoint level. The functional unit was defined as 1 kg of BC (dry mass), in 138.8 kg of water.
Results
From the total used resources (38.9 ton/kg of BC), water is the main one (36.1 ton/kg of BC), most of which (98%) is returned to fresh waters after treatment. The production of raw materials consumed 17.8 ton of water/kg of BC, 13.8 ton/kg of BC of which was for the production of carton packaging, culture medium raw materials, and sodium hydroxide (for the washing of BC). The remaining consumed water was mainly for the fermentation (3.9 ton/kg) and downstream process (7.7 ton/kg). From the identified potential environmental impacts, the production of raw materials had the highest impact, mainly on Climate change, Fossil depletion, Human toxicity, non-cancer, and Terrestrial toxicity. The sodium dihydrogen phosphate production, used in the culture medium, showed the highest environmental impacts in Human toxicity, non-cancer and Terrestrial ecotoxicity, followed by corn syrup and carton production. The static culture fermentation and downstream process showed impact in Climate change and Fossil depletion.
Conclusions
Per se, the BC production process had a small contribution to the consumption of resources and environmental impact of the BC global life cycle.This study was supported by the Portuguese Foundation
for Science and Technology (FCT) within the scope of the strate gic funding of UIDB/04469/2020 and UIDB/00511/2020 units and
MultiBiorefinery project (SAICTPAC/0040/2015-POCI-01-0145-
FEDER-016403). This study was also supported by The Navigator
Company through the I&D no. 21874, “Inpactus-–Produtos e Tecno logias Inovadores a partir do Eucalipto”, funded through the European
Regional Development Fund (ERDF) and the Programa Operacional
Competitividade e Internacionalização (POCI) is greatly acknowl edged. The work by Belmira Neto was fnancially supported by Base
Funding—UIDB/00511/2020 of the Laboratory for Process Engineer ing, Environment, Biotechnology and Energy—LEPABE—funded by
national funds through the FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio
Effect of Ultrasonic-Assisted Blanching on Size Variation, Heat Transfer, and Quality Parameters of Mushrooms
The main aim of this work was to assess the influence
of the application of power ultrasound during blanching
of mushrooms (60 90 °C) on the shrinkage, heat transfer, and
quality parameters. Kinetics of mushroom shrinkage was
modeled and coupled to a heat transfer model for conventional
(CB) and ultrasonic-assisted blanching (UB). Cooking value
and the integrated residual enzymatic activity were obtained
through predicted temperatures and related to the hardness and
color variations of mushrooms, respectively. The application
of ultrasound led to an increase of shrinkage and heat transfer
rates, being this increase more intense at low process temperatures.
Consequently, processing time was decreased (30.7
46.0 %) and a reduction in hardness (25.2 40.8 %) and
lightness (13.8 16.8 %) losses were obtained. The best retention
of hardness was obtained by the UB at 60 °C, while to
maintain the lightness it was the CB and UB at 90 °C. For
enhancing both quality parameters simultaneously, a combined
treatment (CT), which consisted of a CB 0.5 min at
90 °C and then an UB 19.9min at 60 °C, was designed. In this
manner, compared with the conventional treatment at 60 °C,
reductions of 39.1, 27.2, and 65.5 % for the process time,
hardness and lightness losses were achieved, respectively.
These results suggest that the CT could be considered as an
interesting alternative to CB in order to reduce the processing
time and improve the overall quality of blanched mushrooms.The authors acknowledge the financial support of Consejo Nacional de Investigaciones Cientificas y Tecnicas and Universidad Nacional de La Plata from Argentina, Erasmus Mundus Action 2-Strand 1 and EuroTango II Researcher Training Program and Ministerio de Economia y Competitividad (SPAIN) and the FEDER (project DPI2012-37466-CO3-03).Lespinard, A.; Bon CorbĂn, J.; Cárcel CarriĂłn, JA.; Benedito Fort, JJ.; Mascheroni, RH. (2015). Effect of Ultrasonic-Assisted Blanching on Size Variation, Heat Transfer, and Quality Parameters of Mushrooms. Food and Bioprocess Technology. 8(1):41-53. https://doi.org/10.1007/s11947-014-1373-zS415381Aguirre, L., Frias, J. M., Barry-Ryan, C., & Grogan, H. (2009). Modelling browning and brown spotting of mushrooms (Agaricus bisporus) stored in controlled environmental conditions using image analysis. Journal of Food Engineering, 91, 280–286.Anantheswaran, R. C., Sastry, S. K., Beelman, R. 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Multisite observations of SU Aurigae
We present results from the 1996 MUSICOS (MUlti-SIte COntinuous Spectroscopy)
campaign on the T Tauri star SU Aurigae. We find a 2.7-d periodicity in the He
I (587.6 nm) line and somewhat longer, less well-pronounced periodicities in
the Balmer lines and in Na D. Our observations support the suggestion that the
wind and infall signatures are out of phase on SU Aur. We present Doppler
images of SU Aur that have been obtained from least-squares deconvolved
profiles. Images taken about one rotation apart show only limited overlap, in
particular at low latitudes. This is in part due to limitations in
signal-to-noise, and in part due to line profile deformations that arise from
short-lived and/or non-surface features. The agreement at high latitudes is
better and suggests that at least some longer-lived features are present. The
analysis of Stokes V profiles yields a marginal magnetic field detection during
one of the phases.Comment: 22 pages, 20 figures, accepted for publication in MNRA
The Luminosities and Distance Scales of Type II Cepheid and RR Lyrae variables
Infrared and optical absolute magnitudes are derived for the type II Cepheids
kappa Pav and VY Pyx from revised Hipparcos parallaxes and for kappa Pav, V553
Cen and SW Tau from pulsation parallaxes. Phase-corrected JHK mags are given
for 142 RR Lyrae variables based on 2MASS data. RR Lyrae itself is overluminous
compared with LMC RR Lyraes at the classical Cepheid modulus (18.39) consistent
with a prediction of Catalan and Cortes. V553 Cen and SW Tau deviate by only
0.02 mag in the mean from the Matsunaga PL(K) relation for globular cluster
type II Cepheids with a zero-point based on the same LMC modulus. Comparing
directly these two stars with type II Cepheids in the LMC and in the Galactic
Bulge leads to an LMC modulus of 18.37\pm0.09 and a distance to the Galactic
Centre of 7.64\pm 0.21kpc. Kappa Pav may be a binary. V553 Cen and SW Tau show
that at optical wavelengths PL relations are wider for field stars than for
those in globular clusters (abridged).Comment: 29 pages, 13 figures, accepted for MNRA
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