12,133 research outputs found
Investigating Fatigue Performance on the Foamed Asphalt Specimens Generated Using Different Foam Properties
An evaluation of fatigue resistance for foamed asphalt mixture is very demanding since the binder is not continuously distributed on the aggregate surface and this mixtures contains water, the content of which dramatically affects the mechanical properties. This paper discusses the results of laboratory fatigue testingon the foamed asphalt mixtures in which the specimens are generated using three different foamed bitumen properties. Foamed bitumen as the binder was produced at three different foaming water content (FWC) at a temperature of 180oC using a 70/100 pen. The aggregates were mechanically mixed with foamed bitumen using a Hobart mixer. The resulting mixtures were then compacted using a gyratory compactor to generatespecimen with diameter of 100 mm. The specimens were fatigue tested at various stress levels at a temperature of 20oC following a curing period of 3 days at 40oC. Overall, fatigue performance of foamed asphalt can be identified based upon both stress and strain for mixtures produced at FWC 1%, 5%, and 10%
Processamento de lingüiça frescal e defumada de caprinos e ovinos.
Derivados cárneos; Lingüiças frescal e defumada: fluxograma do processamento de lingüiças; Passo a passo para a elaboração industrial da lingüiça; Formulação para elaboração de lingüiças de carne caprina e ovina sem adição de gordura suína.bitstream/CNPC/20710/1/cot78.pd
First detection of CF+ towards a high-mass protostar
We report the first detection of the J = 1 - 0 (102.6 GHz) rotational lines
of CF+ (fluoromethylidynium ion) towards CygX-N63, a young and massive
protostar of the Cygnus X region. This detection occurred as part of an
unbiased spectral survey of this object in the 0.8-3 mm range, performed with
the IRAM 30m telescope. The data were analyzed using a local thermodynamical
equilibrium model (LTE model) and a population diagram in order to derive the
column density. The line velocity (-4 km s-1) and line width (1.6 km s-1)
indicate an origin from the collapsing envelope of the protostar.
We obtain a CF+ column density of 4.10e11 cm-2. The CF+ ion is thought to be
a good tracer for C+ and assuming a ratio of 10e-6 for CF+/C+, we derive a
total number of C+ of 1.2x10e53 within the beam. There is no evidence of carbon
ionization caused by an exterior source of UV photons suggesting that the
protostar itself is the source of ionization. Ionization from the protostellar
photosphere is not efficient enough. In contrast, X-ray ionization from the
accretion shock(s) and UV ionization from outflow shocks could provide a large
enough ionizing power to explain our CF+ detection.
Surprisingly, CF+ has been detected towards a cold, massive protostar with no
sign of an external photon dissociation region (PDR), which means that the only
possibility is the existence of a significant inner source of C+. This is an
important result that opens interesting perspectives to study the early
development of ionized regions and to approach the issue of the evolution of
the inner regions of collapsing envelopes of massive protostars. The existence
of high energy radiations early in the evolution of massive protostars also has
important implications for chemical evolution of dense collapsing gas and could
trigger peculiar chemistry and early formation of a hot core.Comment: 6 page
On a generalised model for time-dependent variance with long-term memory
The ARCH process (R. F. Engle, 1982) constitutes a paradigmatic generator of
stochastic time series with time-dependent variance like it appears on a wide
broad of systems besides economics in which ARCH was born. Although the ARCH
process captures the so-called "volatility clustering" and the asymptotic
power-law probability density distribution of the random variable, it is not
capable to reproduce further statistical properties of many of these time
series such as: the strong persistence of the instantaneous variance
characterised by large values of the Hurst exponent (H > 0.8), and asymptotic
power-law decay of the absolute values self-correlation function. By means of
considering an effective return obtained from a correlation of past returns
that has a q-exponential form we are able to fix the limitations of the
original model. Moreover, this improvement can be obtained through the correct
choice of a sole additional parameter, . The assessment of its validity
and usefulness is made by mimicking daily fluctuations of SP500 financial
index.Comment: 6 pages, 4 figure
Chromosomal mapping of genes encoding subunits of complex I from Neurospora crassa
The genes encoding the 21 kDa protein and the 19.3 kDa, 21.3 kDa and 24 kDa iron-sulfur subunits of complex I were located, by RFLP analysis, in Linkage Groups IV, VI, VI and V, respectively, of the Neurospora crassa genom
Bayesian inference with an adaptive proposal density for GARCH models
We perform the Bayesian inference of a GARCH model by the Metropolis-Hastings
algorithm with an adaptive proposal density. The adaptive proposal density is
assumed to be the Student's t-distribution and the distribution parameters are
evaluated by using the data sampled during the simulation. We apply the method
for the QGARCH model which is one of asymmetric GARCH models and make empirical
studies for for Nikkei 225, DAX and Hang indexes. We find that autocorrelation
times from our method are very small, thus the method is very efficient for
generating uncorrelated Monte Carlo data. The results from the QGARCH model
show that all the three indexes show the leverage effect, i.e. the volatility
is high after negative observations
A unification in the theory of linearization of second order nonlinear ordinary differential equations
In this letter, we introduce a new generalized linearizing transformation
(GLT) for second order nonlinear ordinary differential equations (SNODEs). The
well known invertible point (IPT) and non-point transformations (NPT) can be
derived as sub-cases of the GLT. A wider class of nonlinear ODEs that cannot be
linearized through NPT and IPT can be linearized by this GLT. We also
illustrate how to construct GLTs and to identify the form of the linearizable
equations and propose a procedure to derive the general solution from this GLT
for the SNODEs. We demonstrate the theory with two examples which are of
contemporary interest.Comment: 8 page
Avaliação da dormência em acessos precoces do bag amendoim.
Sementes de amendoim apresentam dormência em diferentes graus, sendo esta característica mais pronunciada na subespécie hypogaea e em variedades de ciclo mais longo. A dormência é interessante do ponto de visto agronômico por evitar perdas durante a colheita e por estar relacionada à menor contaminação por aflatoxinas. Trinta e três acessos, com ciclo entre 90 e 100 dias, do Banco Ativo de Germoplasma de Amendoim foram avaliados quanto à dormência das sementes 14 dias após a colheita. Vinte sementes de cada acesso, tratadas com fungicida, foram dispostas em papel germitest umedecido em incubadas a 30 oC em germinador no Laboratório de Qualidade de Sementes da Embrapa Arroz e Feijão
Improving the Knowledge on Seismogenic Sources in the Lower Tagus Valley for Seismic Hazard Purposes
The Lower Tagus Valley, that includes the metropolitan area of Lisbon, has been struck by several earthquakes which produced significant material damage and loss of lives. Their exact location remains unknown. Our goal is to shed some light into the seismogenic sources in the area using seismic reflection and geological data. In areas with no seismic coverage, potential-field data interpretation was carried out. Seismicity was overlaid to the potential seismogenic structures and high-resolution data was acquired in order to confirm which structures have been active into the Quaternary. Three major fault-zones affecting the Neogene were identified: V. F. Xira, Samora-Alcochete and Pinhal Novo. For the first fault, strong evidences suggest it is active. The other two fault-zones and other structures previously unknown can be correlated with several epicentres. Empirical relationships between maximum moment magnitude and fault area indicate that MW > 6.5 earthquakes can be expected for the larger structures
The W43-MM1 mini-starburst ridge, a test for star formation efficiency models
Context: Star formation efficiency (SFE) theories are currently based on
statistical distributions of turbulent cloud structures and a simple model of
star formation from cores. They remain poorly tested, especially at the highest
densities. Aims: We investigate the effects of gas density on the SFE through
measurements of the core formation efficiency (CFE). With a total mass of
M, the W43-MM1 ridge is one of the most convincing
candidate precursor of starburst clusters and thus one of the best place to
investigate star formation. Methods: We used high-angular resolution maps
obtained at 3 mm and 1 mm within W43-MM1 with the IRAM Plateau de Bure
Interferometer to reveal a cluster of 11 massive dense cores (MDCs), and, one
of the most massive protostellar cores known. An Herschel column density image
provided the mass distribution of the cloud gas. We then measured the
'instantaneous' CFE and estimated the SFE and the star formation rate (SFR)
within subregions of the W43-MM1 ridge. Results: The high SFE found in the
ridge (6% enclosed in 8 pc) confirms its ability to form a
starburst cluster. There is however a clear lack of dense cores in the northern
part of the ridge, which may be currently assembling. The CFE and the SFE are
observed to increase with volume gas density while the SFR steeply decreases
with the virial parameter, . Statistical models of the SFR may
well describe the outskirts of the W43-MM1 ridge but struggle to reproduce its
inner part, which corresponds to measurements at low . It may be
that ridges do not follow the log-normal density distribution, Larson
relations, and stationary conditions forced in the statistical SFR models.Comment: 13 pages, 7 figures. Accepted by A&
- …